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Leitão AB, Arunkumar R, Day JP, Hanna N, Devi A, Hayes MP, Jiggins FM. Recognition of nonself is necessary to activate Drosophila's immune response against an insect parasite. BMC Biol 2024; 22:89. [PMID: 38644510 PMCID: PMC11034056 DOI: 10.1186/s12915-024-01886-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2023] [Accepted: 04/11/2024] [Indexed: 04/23/2024] Open
Abstract
BACKGROUND Innate immune responses can be activated by pathogen-associated molecular patterns (PAMPs), danger signals released by damaged tissues, or the absence of self-molecules that inhibit immunity. As PAMPs are typically conserved across broad groups of pathogens but absent from the host, it is unclear whether they allow hosts to recognize parasites that are phylogenetically similar to themselves, such as parasitoid wasps infecting insects. RESULTS Parasitoids must penetrate the cuticle of Drosophila larvae to inject their eggs. In line with previous results, we found that the danger signal of wounding triggers the differentiation of specialized immune cells called lamellocytes. However, using oil droplets to mimic infection by a parasitoid wasp egg, we found that this does not activate the melanization response. This aspect of the immune response also requires exposure to parasite molecules. The unidentified factor enhances the transcriptional response in hemocytes and induces a specific response in the fat body. CONCLUSIONS We conclude that a combination of danger signals and the recognition of nonself molecules is required to activate Drosophila's immune response against parasitic insects.
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Affiliation(s)
- Alexandre B Leitão
- Department of Genetics, University of Cambridge, Cambridge, UK.
- Champalimaud Foundation, Lisbon, Portugal.
| | | | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Nancy Hanna
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Aarathi Devi
- Department of Genetics, University of Cambridge, Cambridge, UK
- Royal College of Surgeons in Ireland, Dublin, Ireland
| | - Matthew P Hayes
- Department of Zoology, University of Cambridge, Cambridge, UK
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2
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Salje H, Jiggins FM. Risks of releasing imperfect Wolbachia strains for arbovirus control. Lancet Microbe 2024:S2666-5247(24)00072-7. [PMID: 38642566 DOI: 10.1016/s2666-5247(24)00072-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2024] [Revised: 03/01/2024] [Accepted: 03/04/2024] [Indexed: 04/22/2024]
Affiliation(s)
- Henrik Salje
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK.
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
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3
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Zhou SO, Arunkumar R, Irfan A, Ding SD, Leitão AB, Jiggins FM. The evolution of constitutively active humoral immune defenses in Drosophila populations under high parasite pressure. PLoS Pathog 2024; 20:e1011729. [PMID: 38206983 PMCID: PMC10807768 DOI: 10.1371/journal.ppat.1011729] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 01/24/2024] [Accepted: 01/04/2024] [Indexed: 01/13/2024] Open
Abstract
Both constitutive and inducible immune mechanisms are employed by hosts for defense against infection. Constitutive immunity allows for a faster response, but it comes with an associated cost that is always present. This trade-off between speed and fitness costs leads to the theoretical prediction that constitutive immunity will be favored where parasite exposure is frequent. We selected populations of Drosophila melanogaster under high parasite pressure from the parasitoid wasp Leptopilina boulardi. With RNA sequencing, we found the evolution of resistance in these populations was associated with them developing constitutively active humoral immunity, mediated by the larval fat body. Furthermore, these evolved populations were also able to induce gene expression in response to infection to a greater level, which indicates an overall more activated humoral immune response to parasitization. The anti-parasitoid immune response also relies on the JAK/STAT signaling pathway being activated in muscles following infection, and this induced response was only seen in populations that had evolved under high parasite pressure. We found that the cytokine Upd3, which induces this JAK/STAT response, is being expressed by immature lamellocytes. Furthermore, these immune cells became constitutively present when populations evolved resistance, potentially explaining why they gained the ability to activate JAK/STAT signaling. Thus, under intense parasitism, populations evolved resistance by increasing both constitutive and induced immune defenses, and there is likely an interplay between these two forms of immunity.
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Affiliation(s)
- Shuyu Olivia Zhou
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ramesh Arunkumar
- Section of population genetics, School of Life Sciences, Technical University of Munich, Freising, Germany
| | - Amina Irfan
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | | | - Alexandre B. Leitão
- Champalimaud Foundation, Champalimaud Centre of the Unknown, Lisbon, Portugal
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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Leitão AB, Geldman EM, Jiggins FM. Activation of immune defences against parasitoid wasps does not underlie the cost of infection. Front Immunol 2023; 14:1275923. [PMID: 38130722 PMCID: PMC10733856 DOI: 10.3389/fimmu.2023.1275923] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2023] [Accepted: 11/14/2023] [Indexed: 12/23/2023] Open
Abstract
Parasites reduce the fitness of their hosts, and different causes of this damage have fundamentally different consequences for the evolution of immune defences. Damage to the host may result from the parasite directly harming its host, often due to the production of virulence factors that manipulate host physiology. Alternatively, the host may be harmed by the activation of its own immune defences, as these can be energetically demanding or cause self-harm. A well-studied model of the cost of infection is Drosophila melanogaster and its common natural enemy, parasitoid wasps. Infected Drosophila larvae rely on humoral and cellular immune mechanisms to form a capsule around the parasitoid egg and kill it. Infection results in a developmental delay and reduced adult body size. To disentangle the effects of virulence factors and immune defences on these costs, we artificially activated anti-parasitoid immune defences in the absence of virulence factors. Despite immune activation triggering extensive differentiation and proliferation of immune cells together with hyperglycaemia, it did not result in a developmental delay or reduced body size. We conclude that the costs of infection do not result from these aspects of the immune response and may instead result from the parasite directly damaging the host.
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Affiliation(s)
- Alexandre B. Leitão
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Champalimaud Neuroscience Progamme, Champalimaud Centre for the Unknown, Champalimaud Foundation, Lisbon, Portugal
| | - Emma M. Geldman
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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5
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Arunkumar R, Zhou SO, Day JP, Bakare S, Pitton S, Zhang Y, Hsing CY, O’Boyle S, Pascual-Gil J, Clark B, Chandler RJ, Leitão AB, Jiggins FM. Natural selection has driven the recurrent loss of an immunity gene that protects Drosophila against a major natural parasite. Proc Natl Acad Sci U S A 2023; 120:e2211019120. [PMID: 37552757 PMCID: PMC10438844 DOI: 10.1073/pnas.2211019120] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Accepted: 06/26/2023] [Indexed: 08/10/2023] Open
Abstract
Polymorphisms in immunity genes can have large effects on susceptibility to infection. To understand the origins of this variation, we have investigated the genetic basis of resistance to the parasitoid wasp Leptopilina boulardi in Drosophila melanogaster. We found that increased expression of the gene lectin-24A after infection by parasitic wasps was associated with a faster cellular immune response and greatly increased rates of killing the parasite. lectin-24A encodes a protein that is strongly up-regulated in the fat body after infection and localizes to the surface of the parasite egg. In certain susceptible lines, a deletion upstream of the lectin-24A has largely abolished expression. Other mutations predicted to abolish the function of this gene have arisen recurrently in this gene, with multiple loss-of-expression alleles and premature stop codons segregating in natural populations. The frequency of these alleles varies greatly geographically, and in some southern African populations, natural selection has driven them near to fixation. We conclude that natural selection has favored the repeated loss of an important component of the immune system, suggesting that in some populations, a pleiotropic cost to lectin-24A expression outweighs the benefits of resistance.
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Affiliation(s)
- Ramesh Arunkumar
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Shuyu Olivia Zhou
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Jonathan P. Day
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Sherifat Bakare
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
- Department of Biochemical Sciences, School of Biosciences, University of Surrey, 388 Stag Hill, Guildford,GU2 7XH, United Kingdom
| | - Simone Pitton
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
- Biosciences Department, Università degli Studi di Milano, Via Celoria 26, Milano, MI20133, Italy
| | - Yexin Zhang
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Chi-Yun Hsing
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Sinead O’Boyle
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
- School of Biomolecular and Biomedical Science, University College Dublin, DublinD04 V1W8, Ireland
| | - Juan Pascual-Gil
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
- Facultad de Ciencias, Universidad Autónoma de Madrid, C. Francisco Tomás y Valiente 7, 28049Madrid, Spain
| | - Belinda Clark
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Rachael J. Chandler
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
- Department of Biochemical Sciences, School of Biosciences, University of Surrey, 388 Stag Hill, Guildford,GU2 7XH, United Kingdom
| | - Alexandre B. Leitão
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, School of Biological Sciences, University of Cambridge, Downing Street, CambridgeCB2 3EH, United Kingdom
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6
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Bruner-Montero G, Jiggins FM. Wolbachia protects Drosophila melanogaster against two naturally occurring and virulent viral pathogens. Sci Rep 2023; 13:8518. [PMID: 37231093 PMCID: PMC10212958 DOI: 10.1038/s41598-023-35726-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Accepted: 05/23/2023] [Indexed: 05/27/2023] Open
Abstract
Wolbachia is a common endosymbiont that can protect insects against viral pathogens. However, whether the antiviral effects of Wolbachia have a significant effect on fitness remains unclear. We have investigated the interaction between Drosophila melanogaster, Wolbachia and two viruses that we recently isolated from wild flies, La Jolla virus (LJV; Iflaviridae) and Newfield virus (NFV; Permutotetraviridae). Flies infected with these viruses have increased mortality rates, and NFV partially sterilizes females. These effects on fitness were reduced in Wolbachia-infected flies, and this was associated with reduced viral titres. However, Wolbachia alone also reduces survival, and under our experimental conditions these costs of the symbiont can outweigh the benefits of antiviral protection. In contrast, protection against the sterilizing effect of NFV leads to a net benefit of Wolbachia infection after exposure to the virus. These results support the hypothesis that Wolbachia is an important defense against the natural pathogens of D. melanogaster. Furthermore, by reducing the cost of Wolbachia infection, the antiviral effects of Wolbachia may aid its invasion into populations and help explain why it is so common in nature.
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Affiliation(s)
- Gaspar Bruner-Montero
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK.
- Coiba Scientific Station, City of Knowledge, 0843-03081, Clayton, Panama.
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK.
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7
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Detcharoen M, Jiggins FM, Schlick-Steiner BC, Steiner FM. Wolbachia endosymbiotic bacteria alter the gut microbiome in the fly Drosophila nigrosparsa. J Invertebr Pathol 2023; 198:107915. [PMID: 36958642 DOI: 10.1016/j.jip.2023.107915] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 03/09/2023] [Accepted: 03/19/2023] [Indexed: 03/25/2023]
Abstract
Wolbachia are known to cause reproductive manipulations and in some arthropod species, Wolbachia were reported to cause changes in gut microbiome. However, the effects of Wolbachia bacteria on the microbiomes of their hosts, including Drosophila flies, have not been fully accessed. Here, we checked the bacterial microbiome in guts of Wolbachia-uninfected and of Wolbachia-infected Drosophila nigrosparsa, both separated into a bleach-only (embryos bleached) and a gnotobiotic (embryos bleached and inoculated with bacteria) treatment. We observed a clear separation between the Wolbachia-infected and the Wolbachia-uninfected samples, and the infected samples had higher variation in alpha diversity than the uninfected ones. There were reductions in the abundances of Proteobacteria (Pseudomonadota), especially Acetobacter, in the infected samples of both treatments. These findings highlight that Wolbachia change the gut microbiome in D. nigrosparsa as well as that the interactions between Wolbachia and bacteria like Acetobacter need to be investigated.
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Affiliation(s)
- Matsapume Detcharoen
- Molecular Ecology Group, Department of Ecology, Universität Innsbruck, Innsbruck, Austria; Division of Biological Science, Faculty of Science, Prince of Songkla University, Hat Yai, Thailand.
| | | | | | - Florian M Steiner
- Molecular Ecology Group, Department of Ecology, Universität Innsbruck, Innsbruck, Austria
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8
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Ding SD, Leitão AB, Day JP, Arunkumar R, Phillips M, Zhou SO, Jiggins FM. Trans-regulatory changes underpin the evolution of the Drosophila immune response. PLoS Genet 2022; 18:e1010453. [PMID: 36342922 PMCID: PMC9671443 DOI: 10.1371/journal.pgen.1010453] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Revised: 11/17/2022] [Accepted: 09/29/2022] [Indexed: 11/09/2022] Open
Abstract
When an animal is infected, the expression of a large suite of genes is changed, resulting in an immune response that can defend the host. Despite much evidence that the sequence of proteins in the immune system can evolve rapidly, the evolution of gene expression is comparatively poorly understood. We therefore investigated the transcriptional response to parasitoid wasp infection in Drosophila simulans and D. sechellia. Although these species are closely related, there has been a large scale divergence in the expression of immune-responsive genes in their two main immune tissues, the fat body and hemocytes. Many genes, including those encoding molecules that directly kill pathogens, have cis regulatory changes, frequently resulting in large differences in their expression in the two species. However, these changes in cis regulation overwhelmingly affected gene expression in immune-challenged and uninfected animals alike. Divergence in the response to infection was controlled in trans. We argue that altering trans-regulatory factors, such as signalling pathways or immune modulators, may allow natural selection to alter the expression of large numbers of immune-responsive genes in a coordinated fashion. A fundamental question in biology is the nature of the genetic changes underlying evolutionary change, and immune systems provide an ideal system to examine this as they tend to evolve fast as animals adapt to an ever-changing array of parasites and pathogens. Comparing two species of the fruit fly Drosophila, we found that the transcriptional response to infection evolves extremely fast. However, changes in cis (where the genetic change is on the same DNA molecule as the gene in question) and trans (where the genetic change can be elsewhere in the genome) are playing different roles. Changes in cis frequently caused large differences in immune gene expression between species, but these differences were seen regardless of whether the animal was infected. In contrast, changes in trans were responsible for altering how gene expression changes in response to infection. Immune responses are complex and multifaceted, requiring the expression of many genes to be altered in a tightly regulated manner when the animal is infected. Natural selection acting on trans regulatory factors may allow the expression of many downstream genes to be altered in a coordinated fashion.
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Affiliation(s)
| | - Alexandre B. Leitão
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Champalimaud Foundation, Lisbon, Portugal
| | - Jonathan P. Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ramesh Arunkumar
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Morgan Phillips
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Shuyu Olivia Zhou
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
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9
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Abstract
Wolbachia is a maternally transmitted bacterial symbiont that is estimated to infect approximately half of arthropod species. In the laboratory it can increase the resistance of insects to viral infection, but its effect on viruses in nature is unknown. Here we report that in a natural population of Drosophila melanogaster, individuals that are infected with Wolbachia are less likely to be infected by viruses. By characterising the virome by metagenomic sequencing and then testing individual flies for infection, we found the protective effect of Wolbachia was virus-specific, with the prevalence of infection being up to 15% greater in Wolbachia-free flies. The antiviral effects of Wolbachia may contribute to its extraordinary ecological success, and in nature the symbiont may be an important component of the antiviral defences of insects.
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Affiliation(s)
- Rodrigo Cogni
- Department of Ecology, University of São Paulo, São Paulo, Brazil.
| | | | - André C Pimentel
- Department of Ecology, University of São Paulo, São Paulo, Brazil
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
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Lue CH, Buffington ML, Scheffer S, Lewis M, Elliott TA, Lindsey ARI, Driskell A, Jandova A, Kimura MT, Carton Y, Kula RR, Schlenke TA, Mateos M, Govind S, Varaldi J, Guerrieri E, Giorgini M, Wang X, Hoelmer K, Daane KM, Abram PK, Pardikes NA, Brown JJ, Thierry M, Poirié M, Goldstein P, Miller SE, Tracey WD, Davis JS, Jiggins FM, Wertheim B, Lewis OT, Leips J, Staniczenko PPA, Hrcek J. DROP: Molecular voucher database for identification of Drosophila parasitoids. Mol Ecol Resour 2021; 21:2437-2454. [PMID: 34051038 DOI: 10.1111/1755-0998.13435] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Revised: 05/11/2021] [Accepted: 05/20/2021] [Indexed: 01/03/2023]
Abstract
Molecular identification is increasingly used to speed up biodiversity surveys and laboratory experiments. However, many groups of organisms cannot be reliably identified using standard databases such as GenBank or BOLD due to lack of sequenced voucher specimens identified by experts. Sometimes a large number of sequences are available, but with too many errors to allow identification. Here, we address this problem for parasitoids of Drosophila by introducing a curated open-access molecular reference database, DROP (Drosophila parasitoids). Identifying Drosophila parasitoids is challenging and poses a major impediment to realize the full potential of this model system in studies ranging from molecular mechanisms to food webs, and in biological control of Drosophila suzukii. In DROP, genetic data are linked to voucher specimens and, where possible, the voucher specimens are identified by taxonomists and vetted through direct comparison with primary type material. To initiate DROP, we curated 154 laboratory strains, 856 vouchers, 554 DNA sequences, 16 genomes, 14 transcriptomes, and six proteomes drawn from a total of 183 operational taxonomic units (OTUs): 114 described Drosophila parasitoid species and 69 provisional species. We found species richness of Drosophila parasitoids to be heavily underestimated and provide an updated taxonomic catalogue for the community. DROP offers accurate molecular identification and improves cross-referencing between individual studies that we hope will catalyse research on this diverse and fascinating model system. Our effort should also serve as an example for researchers facing similar molecular identification problems in other groups of organisms.
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Affiliation(s)
- Chia-Hua Lue
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Department of Biology, Brooklyn College, City University of New York (CUNY), Brooklyn, NY, USA
| | - Matthew L Buffington
- Systematic Entomology Laboratory, ARS/USDA c/o Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Sonja Scheffer
- Systematic Entomology Laboratory, ARS/USDA c/o Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Matthew Lewis
- Systematic Entomology Laboratory, ARS/USDA c/o Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Tyler A Elliott
- Centre for Biodiversity Genomics, University of Guelph, Guelph, ON, Canada
| | | | - Amy Driskell
- Laboratories of Analytical Biology, Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Anna Jandova
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
| | | | - Yves Carton
- "Évolution, Génomes, Comportement, Écologie", CNRS et Université Paris-Saclay, Paris, France
| | - Robert R Kula
- Systematic Entomology Laboratory, ARS/USDA c/o Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Todd A Schlenke
- Department of Entomology, University of Arizona, Tucson, AZ, USA
| | - Mariana Mateos
- Wildlife and Fisheries Sciences Department, Texas A&M University, College Station, TX, USA
| | - Shubha Govind
- The Graduate Center of the City University of New York, New York, NY, USA
| | - Julien Varaldi
- CNRS, Laboratoire de Biométrie et Biologie Evolutive, UMR 5558, Université de Lyon, Université Lyon 1, Villeurbanne, France
| | - Emilio Guerrieri
- CNR-Institute for Sustainable Plant Protection (CNR-IPSP), National Research Council of Italy, Portici, Italy
| | - Massimo Giorgini
- CNR-Institute for Sustainable Plant Protection (CNR-IPSP), National Research Council of Italy, Portici, Italy
| | - Xingeng Wang
- United States Department of Agriculture, Agricultural Research Services, Beneficial Insects Introduction Research Unit, Newark, DE, USA
| | - Kim Hoelmer
- United States Department of Agriculture, Agricultural Research Services, Beneficial Insects Introduction Research Unit, Newark, DE, USA
| | - Kent M Daane
- Department of Environmental Science, Policy and Management, University of California, Berkeley, CA, USA
| | - Paul K Abram
- Agriculture and Agri-Food Canada, Agassiz Research and Development Centre, Agassiz, BC, Canada
| | - Nicholas A Pardikes
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
| | - Joel J Brown
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Branisovska 31, Czech Republic
| | - Melanie Thierry
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Branisovska 31, Czech Republic
| | - Marylène Poirié
- INRAE, CNRS. and Evolution and Specificity of Multitrophic Interactions (ESIM) Sophia Agrobiotech Institute, Université "Côte d'Azur", Sophia Antipolis, France
| | - Paul Goldstein
- Systematic Entomology Laboratory, ARS/USDA c/o Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - Scott E Miller
- Smithsonian Institution, National Museum of Natural History, Washington, DC, USA
| | - W Daniel Tracey
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
- Gill Center for Biomolecular Science, Indiana University Bloomington, Bloomington, IN, USA
| | - Jeremy S Davis
- Department of Biology, Indiana University Bloomington, Bloomington, IN, USA
- Biology Department, University of Kentucky, Lexington, KY, USA
| | | | - Bregje Wertheim
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, the Netherlands
| | - Owen T Lewis
- Department of Zoology, University of Oxford, Oxford, UK
| | - Jeff Leips
- Department of Biological Sciences, University of Maryland Baltimore County, Baltimore, MD, USA
| | - Phillip P A Staniczenko
- Department of Biology, Brooklyn College, City University of New York (CUNY), Brooklyn, NY, USA
| | - Jan Hrcek
- Biology Centre of the Czech Academy of Sciences, Institute of Entomology, Ceske Budejovice, Czech Republic
- Faculty of Science, University of South Bohemia, Branisovska 31, Czech Republic
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11
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Abstract
Cytoplasmic incompatibility is a selfish reproductive manipulation induced by the endosymbiont Wolbachia in arthropods. In males Wolbachia modifies sperm, leading to embryonic mortality in crosses with Wolbachia-free females. In females, Wolbachia rescues the cross and allows development to proceed normally. This provides a reproductive advantage to infected females, allowing the maternally transmitted symbiont to spread rapidly through host populations. We identified homologs of the genes underlying this phenotype, cifA and cifB, in 52 of 71 new and published Wolbachia genome sequences. They are strongly associated with cytoplasmic incompatibility. There are up to seven copies of the genes in each genome, and phylogenetic analysis shows that Wolbachia frequently acquires new copies due to pervasive horizontal transfer between strains. In many cases, the genes have subsequently acquired loss-of-function mutations to become pseudogenes. As predicted by theory, this tends to occur first in cifB, whose sole function is to modify sperm, and then in cifA, which is required to rescue the cross in females. Although cif genes recombine, recombination is largely restricted to closely related homologs. This is predicted under a model of coevolution between sperm modification and embryonic rescue, where recombination between distantly related pairs of genes would create a self-incompatible strain. Together, these patterns of gene gain, loss, and recombination support evolutionary models of cytoplasmic incompatibility.
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Affiliation(s)
- Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, United Kingdom
| | - Lisa Klasson
- Molecular Evolution, Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden
| | - John J Welch
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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12
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Leitão AB, Arunkumar R, Day JP, Geldman EM, Morin-Poulard I, Crozatier M, Jiggins FM. Constitutive activation of cellular immunity underlies the evolution of resistance to infection in Drosophila. eLife 2020; 9:59095. [PMID: 33357377 PMCID: PMC7785293 DOI: 10.7554/elife.59095] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Accepted: 12/23/2020] [Indexed: 12/21/2022] Open
Abstract
Organisms rely on inducible and constitutive immune defences to combat infection. Constitutive immunity enables a rapid response to infection but may carry a cost for uninfected individuals, leading to the prediction that it will be favoured when infection rates are high. When we exposed populations of Drosophila melanogaster to intense parasitism by the parasitoid wasp Leptopilina boulardi, they evolved resistance by developing a more reactive cellular immune response. Using single-cell RNA sequencing, we found that immune-inducible genes had become constitutively upregulated. This was the result of resistant larvae differentiating precursors of specialized immune cells called lamellocytes that were previously only produced after infection. Therefore, populations evolved resistance by genetically hard-wiring the first steps of an induced immune response to become constitutive.
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Affiliation(s)
- Alexandre B Leitão
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ramesh Arunkumar
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Emma M Geldman
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Ismaël Morin-Poulard
- Centre de Biologie du Développement, Centre de Biologie Intégrative, University Paul Sabatier, Toulouse, France
| | - Michèle Crozatier
- Centre de Biologie du Développement, Centre de Biologie Intégrative, University Paul Sabatier, Toulouse, France
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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13
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Lewis SH, Ross L, Bain SA, Pahita E, Smith SA, Cordaux R, Miska EA, Lenhard B, Jiggins FM, Sarkies P. ------Widespread conservation and lineage-specific diversification of genome-wide DNA methylation patterns across arthropods. PLoS Genet 2020; 16:e1008864. [PMID: 32584820 PMCID: PMC7343188 DOI: 10.1371/journal.pgen.1008864] [Citation(s) in RCA: 32] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2019] [Revised: 07/08/2020] [Accepted: 05/15/2020] [Indexed: 12/23/2022] Open
Abstract
Cytosine methylation is an ancient epigenetic modification yet its function and extent within genomes is highly variable across eukaryotes. In mammals, methylation controls transposable elements and regulates the promoters of genes. In insects, DNA methylation is generally restricted to a small subset of transcribed genes, with both intergenic regions and transposable elements (TEs) depleted of methylation. The evolutionary origin and the function of these methylation patterns are poorly understood. Here we characterise the evolution of DNA methylation across the arthropod phylum. While the common ancestor of the arthropods had low levels of TE methylation and did not methylate promoters, both of these functions have evolved independently in centipedes and mealybugs. In contrast, methylation of the exons of a subset of transcribed genes is ancestral and widely conserved across the phylum, but has been lost in specific lineages. A similar set of genes is methylated in all species that retained exon-enriched methylation. We show that these genes have characteristic patterns of expression correlating to broad transcription initiation sites and well-positioned nucleosomes, providing new insights into potential mechanisms driving methylation patterns over hundreds of millions of years.
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Affiliation(s)
- Samuel H. Lewis
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Laura Ross
- Institute of Evolutionary Biology, Edinburgh, United Kingdom
| | - Stevie A. Bain
- Institute of Evolutionary Biology, Edinburgh, United Kingdom
| | - Eleni Pahita
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
| | - Stephen A. Smith
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, Virginia Tech, Blacksburg, Virginia, United States of America
| | - Richard Cordaux
- Laboratoire Ecologie et Biologie des Interactions Universite de Poitiers, France
| | - Eric A. Miska
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, United Kingdom
| | - Boris Lenhard
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, Norway
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Peter Sarkies
- MRC London Institute of Medical Sciences, London, United Kingdom
- Institute of Clinical Sciences, Imperial College London, London, United Kingdom
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14
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Kaur R, Martinez J, Rota-Stabelli O, Jiggins FM, Miller WJ. Age, tissue, genotype and virus infection regulate Wolbachia levels in Drosophila. Mol Ecol 2020; 29:2063-2079. [PMID: 32391935 DOI: 10.1111/mec.15462] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2018] [Accepted: 04/28/2020] [Indexed: 12/13/2022]
Abstract
The bacterial symbiont Wolbachia can protect insects against viral pathogens, and the varying levels of antiviral protection are correlated with the endosymbiont load within the insects. To understand why Wolbachia strains differ in their antiviral effects, we investigated the factors controlling Wolbachia density in five closely related strains in their natural Drosophila hosts. We found that Wolbachia density varied greatly across different tissues and between flies of different ages, and these effects depended on the host-symbiont association. Some endosymbionts maintained largely stable densities as flies aged while others increased, and these effects in turn depended on the tissue being examined. Measuring Wolbachia rRNA levels in response to viral infection, we found that viral infection itself also altered Wolbachia levels, with Flock House virus causing substantial reductions in symbiont loads late in the infection. This effect, however, was virus-specific as Drosophila C virus had little impact on Wolbachia in all of the five host systems. Because viruses have strong tissue tropisms and antiviral protection is thought to be cell-autonomous, these effects are likely to affect the virus-blocking phenomenon. However, we were unable to find any evidence of a correlation between Wolbachia and viral titres within the same tissues. We conclude that Wolbachia levels within flies are regulated in a complex host-symbiont-virus-dependent manner and this trinity is likely to influence the antiviral effects of Wolbachia.
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Affiliation(s)
- Rupinder Kaur
- Division of Cell and Developmental Biology, Medical University of Vienna, Vienna, Austria.,Department of Sustainable Agro-Ecosystems and Bioresources, Fondazione Edmund Mach, San Michele all'Adige, Italy.,Department of Neurobiology, University of Vienna, Vienna, Austria.,Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | - Julien Martinez
- MRC-University of Glasgow Centre for Virus Research, University of Glasgow, Glasgow, UK
| | - Omar Rota-Stabelli
- Department of Sustainable Agro-Ecosystems and Bioresources, Fondazione Edmund Mach, San Michele all'Adige, Italy
| | | | - Wolfgang J Miller
- Division of Cell and Developmental Biology, Medical University of Vienna, Vienna, Austria
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15
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Detcharoen M, Arthofer W, Jiggins FM, Steiner FM, Schlick‐Steiner BC. Wolbachia affect behavior and possibly reproductive compatibility but not thermoresistance, fecundity, and morphology in a novel transinfected host, Drosophila nigrosparsa. Ecol Evol 2020; 10:4457-4470. [PMID: 32489610 PMCID: PMC7246211 DOI: 10.1002/ece3.6212] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Revised: 02/28/2020] [Accepted: 03/04/2020] [Indexed: 11/11/2022] Open
Abstract
Wolbachia, intracellular endosymbionts, are estimated to infect about half of all arthropod species. These bacteria manipulate their hosts in various ways for their maximum benefits. The rising global temperature may accelerate species migration, and thus, horizontal transfer of Wolbachia may occur across species previously not in contact. We transinfected and then cured the alpine fly Drosophila nigrosparsa with Wolbachia strain wMel to study its effects on this species. We found low Wolbachia titer, possibly cytoplasmic incompatibility, and an increase in locomotion of both infected larvae and adults compared with cured ones. However, no change in fecundity, no impact on heat and cold tolerance, and no change in wing morphology were observed. Although Wolbachia increased locomotor activities in this species, we conclude that D. nigrosparsa may not benefit from the infection. Still, D. nigrosparsa can serve as a host for Wolbachia because vertical transmission is possible but may not be as high as in the native host of wMel, Drosophila melanogaster.
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16
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Martinez J, Bruner-Montero G, Arunkumar R, Smith SCL, Day JP, Longdon B, Jiggins FM. Virus evolution in Wolbachia-infected Drosophila. Proc Biol Sci 2019; 286:20192117. [PMID: 31662085 DOI: 10.1098/rspb.2019.2117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
Wolbachia, a common vertically transmitted symbiont, can protect insects against viral infection and prevent mosquitoes from transmitting viral pathogens. For this reason, Wolbachia-infected mosquitoes are being released to prevent the transmission of dengue and other arboviruses. An important question for the long-term success of these programmes is whether viruses can evolve to escape the antiviral effects of Wolbachia. We have found that Wolbachia altered the outcome of competition between strains of the DCV virus in Drosophila. However, Wolbachia still effectively blocked the virus genotypes that were favoured in the presence of the symbiont. We conclude that Wolbachia did cause an evolutionary response in viruses, but this has little or no impact on the effectiveness of virus blocking.
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Affiliation(s)
- Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, UK
| | | | | | | | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge, UK.,Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Cornwall TR10 9FE, UK
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17
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Leitão AB, Bian X, Day JP, Pitton S, Demir E, Jiggins FM. Independent effects on cellular and humoral immune responses underlie genotype-by-genotype interactions between Drosophila and parasitoids. PLoS Pathog 2019; 15:e1008084. [PMID: 31589659 PMCID: PMC6797232 DOI: 10.1371/journal.ppat.1008084] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Revised: 10/17/2019] [Accepted: 09/16/2019] [Indexed: 11/18/2022] Open
Abstract
It is common to find abundant genetic variation in host resistance and parasite infectivity within populations, with the outcome of infection frequently depending on genotype-specific interactions. Underlying these effects are complex immune defenses that are under the control of both host and parasite genes. We have found extensive variation in Drosophila melanogaster's immune response against the parasitoid wasp Leptopilina boulardi. Some aspects of the immune response, such as phenoloxidase activity, are predominantly affected by the host genotype. Some, such as upregulation of the complement-like protein Tep1, are controlled by the parasite genotype. Others, like the differentiation of immune cells called lamellocytes, depend on the specific combination of host and parasite genotypes. These observations illustrate how the outcome of infection depends on independent genetic effects on different aspects of host immunity. As parasite-killing results from the concerted action of different components of the immune response, these observations provide a physiological mechanism to generate phenomena like epistasis and genotype-interactions that underlie models of coevolution.
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Affiliation(s)
| | - Xueni Bian
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jonathan P. Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Simone Pitton
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Eşref Demir
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Antalya Bilim University, Faculty of Engineering, Department of Material Science and Nanotechnology Engineering, Dosemealti, Antalya, Turkey
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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18
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Duxbury EML, Day JP, Maria Vespasiani D, Thüringer Y, Tolosana I, Smith SCL, Tagliaferri L, Kamacioglu A, Lindsley I, Love L, Unckless RL, Jiggins FM, Longdon B. Host-pathogen coevolution increases genetic variation in susceptibility to infection. eLife 2019; 8:e46440. [PMID: 31038124 PMCID: PMC6491035 DOI: 10.7554/elife.46440] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2019] [Accepted: 04/07/2019] [Indexed: 12/31/2022] Open
Abstract
It is common to find considerable genetic variation in susceptibility to infection in natural populations. We have investigated whether natural selection increases this variation by testing whether host populations show more genetic variation in susceptibility to pathogens that they naturally encounter than novel pathogens. In a large cross-infection experiment involving four species of Drosophila and four host-specific viruses, we always found greater genetic variation in susceptibility to viruses that had coevolved with their host. We went on to examine the genetic architecture of resistance in one host species, finding that there are more major-effect genetic variants in coevolved host-pathogen interactions. We conclude that selection by pathogens has increased genetic variation in host susceptibility, and much of this effect is caused by the occurrence of major-effect resistance polymorphisms within populations.
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Affiliation(s)
- Elizabeth ML Duxbury
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
- School of Biological SciencesUniversity of East AngliaNorwichUnited Kingdom
| | - Jonathan P Day
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | | | - Yannik Thüringer
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Ignacio Tolosana
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Sophia CL Smith
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Lucia Tagliaferri
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Altug Kamacioglu
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Imogen Lindsley
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Luca Love
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Robert L Unckless
- Department of Molecular BiosciencesUniversity of KansasLawrenceUnited States
| | - Francis M Jiggins
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
| | - Ben Longdon
- Department of GeneticsUniversity of CambridgeCambridgeUnited Kingdom
- Centre for Ecology and Conservation, BiosciencesUniversity of Exeter (Penryn Campus)CornwallUnited Kingdom
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19
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Alves JM, Carneiro M, Cheng JY, Lemos de Matos A, Rahman MM, Loog L, Campos PF, Wales N, Eriksson A, Manica A, Strive T, Graham SC, Afonso S, Bell DJ, Belmont L, Day JP, Fuller SJ, Marchandeau S, Palmer WJ, Queney G, Surridge AK, Vieira FG, McFadden G, Nielsen R, Gilbert MTP, Esteves PJ, Ferrand N, Jiggins FM. Parallel adaptation of rabbit populations to myxoma virus. Science 2019; 363:1319-1326. [PMID: 30765607 DOI: 10.1126/science.aau7285] [Citation(s) in RCA: 87] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Revised: 12/10/2018] [Accepted: 02/01/2019] [Indexed: 12/18/2022]
Abstract
In the 1950s the myxoma virus was released into European rabbit populations in Australia and Europe, decimating populations and resulting in the rapid evolution of resistance. We investigated the genetic basis of resistance by comparing the exomes of rabbits collected before and after the pandemic. We found a strong pattern of parallel evolution, with selection on standing genetic variation favoring the same alleles in Australia, France, and the United Kingdom. Many of these changes occurred in immunity-related genes, supporting a polygenic basis of resistance. We experimentally validated the role of several genes in viral replication and showed that selection acting on an interferon protein has increased the protein's antiviral effect.
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Affiliation(s)
- Joel M Alves
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK. .,CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, 4485-661 Vairão, Portugal.,Palaeogenomics and Bio-Archaeology Research Network Research Laboratory for Archaeology and History of Art, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK
| | - Miguel Carneiro
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, 4485-661 Vairão, Portugal. .,Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal
| | - Jade Y Cheng
- Departments of Integrative Biology and Statistics, University of California, Berkeley, Berkeley, CA 94720, USA.,Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark
| | - Ana Lemos de Matos
- The Biodesign Institute, Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, AZ 85287-5401, USA
| | - Masmudur M Rahman
- The Biodesign Institute, Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, AZ 85287-5401, USA
| | - Liisa Loog
- Palaeogenomics and Bio-Archaeology Research Network Research Laboratory for Archaeology and History of Art, University of Oxford, Dyson Perrins Building, South Parks Road, Oxford OX1 3QY, UK.,Manchester Institute of Biotechnology, School of Earth and Environmental Sciences, University of Manchester, Manchester M1 7DN, UK
| | - Paula F Campos
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark.,CIIMAR, Interdisciplinary Centre of Marine and Environmental Research, University of Porto, Avenida General Norton de Matos, S/N, 4450-208 Matosinhos, Portugal
| | - Nathan Wales
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark.,Department of Plant and Microbial Biology, University of California, 111 Koshland Hall, Berkeley, CA 94720, USA.,Department of Archaeology, University of York, King's Manor, York YO1 7EP, UK
| | - Anders Eriksson
- Department of Medical and Molecular Genetics, King's College London, London SE1 9RT, UK
| | - Andrea Manica
- Department of Zoology, University of Cambridge, Downing Street, Cambridge CB2 3EJ, UK
| | - Tanja Strive
- Health and Biosecurity, Commonwealth Scientific and Industrial Research Organisation, Canberra, ACT 2601, Australia.,Centre for Invasive Species Solutions, University of Canberra, Bruce, ACT 2601, Australia
| | - Stephen C Graham
- Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - Sandra Afonso
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, 4485-661 Vairão, Portugal
| | - Diana J Bell
- Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Laura Belmont
- The Biodesign Institute, Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, AZ 85287-5401, USA
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Susan J Fuller
- School of Earth, Environmental and Biological Sciences, Science and Engineering Faculty, Queensland University of Technology, Brisbane, Australia
| | | | - William J Palmer
- The Genome Center and Department of Plant Sciences, University of California, Davis, CA 95616, USA
| | - Guillaume Queney
- ANTAGENE, Wildlife Genetics Laboratory, La Tour de Salvagny (Lyon), France
| | - Alison K Surridge
- Centre for Ecology, Evolution and Conservation, School of Biological Sciences, University of East Anglia, Norwich NR4 7TJ, UK
| | - Filipe G Vieira
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark
| | - Grant McFadden
- The Biodesign Institute, Center for Immunotherapy, Vaccines, and Virotherapy, Arizona State University, Tempe, AZ 85287-5401, USA
| | - Rasmus Nielsen
- Departments of Integrative Biology and Statistics, University of California, Berkeley, Berkeley, CA 94720, USA.,Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark
| | - M Thomas P Gilbert
- Centre for GeoGenetics, Natural History Museum of Denmark, University of Copenhagen, Copenhagen 1350, Denmark.,Norwegian University of Science and Technology, University Museum, 7491 Trondheim, Norway
| | - Pedro J Esteves
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, 4485-661 Vairão, Portugal.,Instituto de Investigação e Formação Avançada em Ciências e Tecnologias da Saúde (CESPU), Gandra, Portugal
| | - Nuno Ferrand
- CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, InBIO Laboratório Associado, Universidade do Porto, 4485-661 Vairão, Portugal.,Departamento de Biologia, Faculdade de Ciências da Universidade do Porto, 4169-007 Porto, Portugal.,Department of Zoology, Faculty of Sciences, University of Johannesburg, Auckland Park 2006, South Africa
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK.
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20
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Jones MR, Mills LS, Alves PC, Callahan CM, Alves JM, Lafferty DJR, Jiggins FM, Jensen JD, Melo-Ferreira J, Good JM. Adaptive introgression underlies polymorphic seasonal camouflage in snowshoe hares. Science 2018; 360:1355-1358. [DOI: 10.1126/science.aar5273] [Citation(s) in RCA: 182] [Impact Index Per Article: 30.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 05/01/2018] [Indexed: 12/14/2022]
Abstract
Snowshoe hares (Lepus americanus) maintain seasonal camouflage by molting to a white winter coat, but some hares remain brown during the winter in regions with low snow cover. We show that cis-regulatory variation controlling seasonal expression of the Agouti gene underlies this adaptive winter camouflage polymorphism. Genetic variation at Agouti clustered by winter coat color across multiple hare and jackrabbit species, revealing a history of recurrent interspecific gene flow. Brown winter coats in snowshoe hares likely originated from an introgressed black-tailed jackrabbit allele that has swept to high frequency in mild winter environments. These discoveries show that introgression of genetic variants that underlie key ecological traits can seed past and ongoing adaptation to rapidly changing environments.
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21
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Longdon B, Day JP, Schulz N, Leftwich PT, de Jong MA, Breuker CJ, Gibbs M, Obbard DJ, Wilfert L, Smith SCL, McGonigle JE, Houslay TM, Wright LI, Livraghi L, Evans LC, Friend LA, Chapman T, Vontas J, Kambouraki N, Jiggins FM. Vertically transmitted rhabdoviruses are found across three insect families and have dynamic interactions with their hosts. Proc Biol Sci 2018; 284:rspb.2016.2381. [PMID: 28100819 PMCID: PMC5310039 DOI: 10.1098/rspb.2016.2381] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2016] [Accepted: 12/20/2016] [Indexed: 11/17/2022] Open
Abstract
A small number of free-living viruses have been found to be obligately vertically transmitted, but it remains uncertain how widespread vertically transmitted viruses are and how quickly they can spread through host populations. Recent metagenomic studies have found several insects to be infected with sigma viruses (Rhabdoviridae). Here, we report that sigma viruses that infect Mediterranean fruit flies (Ceratitis capitata), Drosophila immigrans, and speckled wood butterflies (Pararge aegeria) are all vertically transmitted. We find patterns of vertical transmission that are consistent with those seen in Drosophila sigma viruses, with high rates of maternal transmission, and lower rates of paternal transmission. This mode of transmission allows them to spread rapidly in populations, and using viral sequence data we found the viruses in D. immigrans and C. capitata had both recently swept through host populations. The viruses were common in nature, with mean prevalences of 12% in C. capitata, 38% in D. immigrans and 74% in P. aegeria. We conclude that vertically transmitted rhabdoviruses may be widespread in a broad range of insect taxa, and that these viruses can have dynamic interactions with their hosts.
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Affiliation(s)
- Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Nora Schulz
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK.,Institute for Evolution and Biodiversity, University of Münster, Münster, Germany
| | - Philip T Leftwich
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Maaike A de Jong
- School of Biological Sciences, University of Bristol, Bristol Life Sciences Building, 24 Tyndall Avenue, Bristol BS8 1TQ, UK
| | - Casper J Breuker
- Evolutionary Developmental Biology Research Group, Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford OX3 0BP, UK
| | - Melanie Gibbs
- NERC Centre for Ecology and Hydrology, Crowmarsh Gifford, Maclean Building, Wallingford, Oxfordshire OX10 8BB, UK
| | - Darren J Obbard
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Laboratories, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Lena Wilfert
- Centre for Ecology and Conservation, Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn Campus TR10 9FE, UK
| | - Sophia C L Smith
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - John E McGonigle
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Thomas M Houslay
- Centre for Ecology and Conservation, Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn Campus TR10 9FE, UK
| | - Lucy I Wright
- Centre for Ecology and Conservation, Biosciences, College of Life and Environmental Sciences, University of Exeter, Penryn Campus TR10 9FE, UK.,Zoological Society of London, Regent's Park, London NW1 4RY, UK
| | - Luca Livraghi
- Evolutionary Developmental Biology Research Group, Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford OX3 0BP, UK
| | - Luke C Evans
- Evolutionary Developmental Biology Research Group, Department of Biological and Medical Sciences, Faculty of Health and Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford OX3 0BP, UK.,Ecology and Evolutionary Biology Research Division, School of Biological Sciences, University of Reading, Whiteknights, Reading RG6 6AS, UK
| | - Lucy A Friend
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - Tracey Chapman
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, UK
| | - John Vontas
- Lab Pesticide Science, Agricultural University of Athens, Iera Odos 75, 11855, Athens, Greece.,Molecular Entomology, Institute Molecular Biology and Biotechnology/Foundation for Research and Technology, Voutes, 70013, Heraklio, Crete, Greece
| | - Natasa Kambouraki
- Lab Pesticide Science, Agricultural University of Athens, Iera Odos 75, 11855, Athens, Greece.,Molecular Entomology, Institute Molecular Biology and Biotechnology/Foundation for Research and Technology, Voutes, 70013, Heraklio, Crete, Greece
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
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22
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Lewis SH, Quarles KA, Yang Y, Tanguy M, Frézal L, Smith SA, Sharma PP, Cordaux R, Gilbert C, Giraud I, Collins DH, Zamore PD, Miska EA, Sarkies P, Jiggins FM. Pan-arthropod analysis reveals somatic piRNAs as an ancestral defence against transposable elements. Nat Ecol Evol 2018; 2:174-181. [PMID: 29203920 PMCID: PMC5732027 DOI: 10.1038/s41559-017-0403-4] [Citation(s) in RCA: 179] [Impact Index Per Article: 29.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 11/02/2017] [Indexed: 02/02/2023]
Abstract
In animals, small RNA molecules termed PIWI-interacting RNAs (piRNAs) silence transposable elements (TEs), protecting the germline from genomic instability and mutation. piRNAs have been detected in the soma in a few animals, but these are believed to be specific adaptations of individual species. Here, we report that somatic piRNAs were probably present in the ancestral arthropod more than 500 million years ago. Analysis of 20 species across the arthropod phylum suggests that somatic piRNAs targeting TEs and messenger RNAs are common among arthropods. The presence of an RNA-dependent RNA polymerase in chelicerates (horseshoe crabs, spiders and scorpions) suggests that arthropods originally used a plant-like RNA interference mechanism to silence TEs. Our results call into question the view that the ancestral role of the piRNA pathway was to protect the germline and demonstrate that small RNA silencing pathways have been repurposed for both somatic and germline functions throughout arthropod evolution.
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Affiliation(s)
- Samuel H Lewis
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
- Medical Research Council London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK.
- Institute for Clinical Sciences, Imperial College London, Du Cane Road, London, W12 0NN, UK.
| | - Kaycee A Quarles
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Yujing Yang
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Melanie Tanguy
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, CB2 1QN, UK
| | - Lise Frézal
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, CB2 1QN, UK
- Institut de Biologie de l'Ecole Normale Supérieure, Centre National de la Recherche Scientifique, Inserm, Ecole Normale Supérieure, Paris Sciences & Lettres Research University, 75005, Paris, France
| | - Stephen A Smith
- Department of Biomedical Sciences and Pathobiology, Virginia Maryland College of Veterinary Medicine, 205 Duck Pond Drive, Virginia Tech, Blacksburg, VA, 24061, USA
| | - Prashant P Sharma
- Department of Zoology, University of Wisconsin-Madison, 352 Birge Hall, 430 Lincoln Drive, Madison, WI, 53706, USA
| | - Richard Cordaux
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpain, TSA 51106, 86073, Poitiers Cedex 9, France
| | - Clément Gilbert
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpain, TSA 51106, 86073, Poitiers Cedex 9, France
- Laboratoire Evolution, Génomes, Comportement, Écologie, Unité Mixte de Recherche 9191 Centre National de la Recherche Scientifique and Unité Mixte de Recherche 247 Institut de Recherche pour le Développement, Université Paris-Sud, 91198, Gif-sur-Yvette, France
| | - Isabelle Giraud
- Université de Poitiers, Laboratoire Ecologie et Biologie des Interactions, Equipe Ecologie Evolution Symbiose, 5 Rue Albert Turpain, TSA 51106, 86073, Poitiers Cedex 9, France
| | - David H Collins
- School of Biological Sciences, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK
| | - Phillip D Zamore
- Howard Hughes Medical Institute, RNA Therapeutics Institute, University of Massachusetts Medical School, 368 Plantation Street, Worcester, MA, 01605, USA
| | - Eric A Miska
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- Wellcome Trust/Cancer Research UK Gurdon Institute, Cambridge, CB2 1QN, UK
| | - Peter Sarkies
- Medical Research Council London Institute of Medical Sciences, Du Cane Road, London, W12 0NN, UK
- Institute for Clinical Sciences, Imperial College London, Du Cane Road, London, W12 0NN, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
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23
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Martinez J, Cogni R, Cao C, Smith S, Illingworth CJR, Jiggins FM. Addicted? Reduced host resistance in populations with defensive symbionts. Proc Biol Sci 2017; 283:rspb.2016.0778. [PMID: 27335421 PMCID: PMC4936038 DOI: 10.1098/rspb.2016.0778] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2016] [Accepted: 05/20/2016] [Indexed: 12/28/2022] Open
Abstract
Heritable symbionts that protect their hosts from pathogens have been described in a wide range of insect species. By reducing the incidence or severity of infection, these symbionts have the potential to reduce the strength of selection on genes in the insect genome that increase resistance. Therefore, the presence of such symbionts may slow down the evolution of resistance. Here we investigated this idea by exposing Drosophila melanogaster populations to infection with the pathogenic Drosophila C virus (DCV) in the presence or absence of Wolbachia, a heritable symbiont of arthropods that confers protection against viruses. After nine generations of selection, we found that resistance to DCV had increased in all populations. However, in the presence of Wolbachia the resistant allele of pastrel-a gene that has a major effect on resistance to DCV-was at a lower frequency than in the symbiont-free populations. This finding suggests that defensive symbionts have the potential to hamper the evolution of insect resistance genes, potentially leading to a state of evolutionary addiction where the genetically susceptible insect host mostly relies on its symbiont to fight pathogens.
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Affiliation(s)
- Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Rodrigo Cogni
- Department of Genetics, University of Cambridge, Cambridge, UK Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, 05508 900 São Paulo, SP, Brazil
| | - Chuan Cao
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Sophie Smith
- Department of Genetics, University of Cambridge, Cambridge, UK
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24
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Campbell CL, Dickson LB, Lozano-Fuentes S, Juneja P, Jiggins FM, Black WC. Alternative patterns of sex chromosome differentiation in Aedes aegypti (L). BMC Genomics 2017; 18:943. [PMID: 29202694 PMCID: PMC5716240 DOI: 10.1186/s12864-017-4348-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 11/23/2017] [Indexed: 12/16/2022] Open
Abstract
Background Some populations of West African Aedes aegypti, the dengue and zika vector, are reproductively incompatible; our earlier study showed that divergence and rearrangements of genes on chromosome 1, which bears the sex locus (M), may be involved. We also previously described a proposed cryptic subspecies SenAae (PK10, Senegal) that had many more high inter-sex FST genes on chromosome 1 than did Ae.aegypti aegypti (Aaa, Pai Lom, Thailand). The current work more thoroughly explores the significance of those findings. Results Intersex standardized variance (FST) of single nucleotide polymorphisms (SNPs) was characterized from genomic exome capture libraries of both sexes in representative natural populations of Aaa and SenAae. Our goal was to identify SNPs that varied in frequency between males and females, and most were expected to occur on chromosome 1. Use of the assembled AaegL4 reference alleviated the previous problem of unmapped genes. Because the M locus gene nix was not captured and not present in AaegL4, the male-determining locus, per se, was not explored. Sex-associated genes were those with FST values ≥ 0.100 and/or with increased expected heterozygosity (Hexp, one-sided T-test, p < 0.05) in males. There were 85 genes common to both collections with high inter-sex FST values; all genes but one were located on chromosome 1. Aaa showed the expected cluster of high inter-sex FST genes proximal to the M locus, whereas SenAae had inter-sex FST genes along the length of chromosome 1. In addition, the Aaa M-locus proximal region showed increased Hexp levels in males, whereas SenAae did not. In SenAae, chromosomal rearrangements and subsequent suppressed recombination may have accelerated X-Y differentiation. Conclusions The evidence presented here is consistent with differential evolution of proto-Y chromosomes in Aaa and SenAae. Electronic supplementary material The online version of this article (doi: 10.1186/s12864-017-4348-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Corey L Campbell
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA.
| | - Laura B Dickson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
| | - Saul Lozano-Fuentes
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - William C Black
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
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25
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Martinez J, Tolosana I, Ok S, Smith S, Snoeck K, Day JP, Jiggins FM. Symbiont strain is the main determinant of variation in Wolbachia-mediated protection against viruses across Drosophila species. Mol Ecol 2017; 26:4072-4084. [PMID: 28464440 PMCID: PMC5966720 DOI: 10.1111/mec.14164] [Citation(s) in RCA: 54] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2016] [Revised: 04/24/2017] [Accepted: 04/25/2017] [Indexed: 12/19/2022]
Abstract
Wolbachia is a common heritable bacterial symbiont in insects. Its evolutionary success lies in the diverse phenotypic effects it has on its hosts coupled to its propensity to move between host species over evolutionary timescales. In a survey of natural host-symbiont associations in a range of Drosophila species, we found that 10 of 16 Wolbachia strains protected their hosts against viral infection. By moving Wolbachia strains between host species, we found that the symbiont genome had a much greater influence on the level of antiviral protection than the host genome. The reason for this was that the level of protection depended on the density of the symbiont in host tissues, and Wolbachia rather than the host-controlled density. The finding that virus resistance and symbiont density are largely under the control of symbiont genes in this system has important implications both for the evolution of these traits and for public health programmes using Wolbachia to prevent mosquitoes from transmitting disease.
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Affiliation(s)
- Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, UK
| | | | - Suzan Ok
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Sophie Smith
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Kiana Snoeck
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, UK
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26
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Crawford JE, Alves JM, Palmer WJ, Day JP, Sylla M, Ramasamy R, Surendran SN, Black WC, Pain A, Jiggins FM. Population genomics reveals that an anthropophilic population of Aedes aegypti mosquitoes in West Africa recently gave rise to American and Asian populations of this major disease vector. BMC Biol 2017; 15:16. [PMID: 28241828 PMCID: PMC5329927 DOI: 10.1186/s12915-017-0351-0] [Citation(s) in RCA: 72] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2016] [Accepted: 01/19/2017] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The mosquito Aedes aegypti is the main vector of dengue, Zika, chikungunya and yellow fever viruses. This major disease vector is thought to have arisen when the African subspecies Ae. aegypti formosus evolved from being zoophilic and living in forest habitats into a form that specialises on humans and resides near human population centres. The resulting domestic subspecies, Ae. aegypti aegypti, is found throughout the tropics and largely blood-feeds on humans. RESULTS To understand this transition, we have sequenced the exomes of mosquitoes collected from five populations from around the world. We found that Ae. aegypti specimens from an urban population in Senegal in West Africa were more closely related to populations in Mexico and Sri Lanka than they were to a nearby forest population. We estimate that the populations in Senegal and Mexico split just a few hundred years ago, and we found no evidence of Ae. aegypti aegypti mosquitoes migrating back to Africa from elsewhere in the tropics. The out-of-Africa migration was accompanied by a dramatic reduction in effective population size, resulting in a loss of genetic diversity and rare genetic variants. CONCLUSIONS We conclude that a domestic population of Ae. aegypti in Senegal and domestic populations on other continents are more closely related to each other than to other African populations. This suggests that an ancestral population of Ae. aegypti evolved to become a human specialist in Africa, giving rise to the subspecies Ae. aegypti aegypti. The descendants of this population are still found in West Africa today, and the rest of the world was colonised when mosquitoes from this population migrated out of Africa. This is the first report of an African population of Ae. aegypti aegypti mosquitoes that is closely related to Asian and American populations. As the two subspecies differ in their ability to vector disease, their existence side by side in West Africa may have important implications for disease transmission.
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Affiliation(s)
- Jacob E Crawford
- Department of Integrative Biology, University of California, Berkeley, CA, 94720-3140, USA
- Present Address: Verily Life Sciences, South San Francisco, CA, 94080, USA
| | - Joel M Alves
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
- CIBIO/InBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Campus Agrário de Vairão, Universidade do Porto, 4485-661, Vairão, Portugal
| | - William J Palmer
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Massamba Sylla
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | | | - Sinnathamby N Surendran
- ID-FISH Technology, Palo Alto, CA, 94303, USA
- Department of Zoology, University of Jaffna, Jaffna, Sri Lanka
| | - William C Black
- Department of Microbiology, Immunology and Pathology, Colorado State University, Fort Collins, CO, USA
| | - Arnab Pain
- Biological and Environmental Sciences and Engineering Division, KAUST, Thuwal, Kingdom of Saudi Arabia
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK.
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27
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Juneja P, Quinn A, Jiggins FM. Latitudinal clines in gene expression and cis-regulatory element variation in Drosophila melanogaster. BMC Genomics 2016; 17:981. [PMID: 27894253 PMCID: PMC5126864 DOI: 10.1186/s12864-016-3333-7] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2016] [Accepted: 11/23/2016] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Organisms can rapidly adapt to their environment when colonizing a new habitat, and this could occur by changing protein sequences or by altering patterns of gene expression. The importance of gene expression in driving local adaptation is increasingly being appreciated, and cis-regulatory elements (CREs), which control and modify the expression of the nearby genes, are predicted to play an important role. Here we investigate genetic variation in gene expression in immune-challenged Drosophila melanogaster from temperate and tropical or sub-tropical populations in Australia and United States. RESULTS We find parallel latitudinal changes in gene expression, with genes involved in immunity, insecticide resistance, reproduction, and the response to the environment being especially likely to differ between latitudes. By measuring allele-specific gene expression (ASE), we show that cis-regulatory variation also shows parallel latitudinal differences between the two continents and contributes to the latitudinal differences in gene expression. CONCLUSIONS Both Australia and United States were relatively recently colonized by D. melanogaster, and it was recently shown that introductions of both African and European flies occurred, with African genotypes contributing disproportionately to tropical populations. Therefore, both the demographic history of the populations and local adaptation may be causing the patterns that we see.
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Affiliation(s)
- Punita Juneja
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Andrew Quinn
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK.
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28
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Cogni R, Cao C, Day JP, Bridson C, Jiggins FM. The genetic architecture of resistance to virus infection in Drosophila. Mol Ecol 2016; 25:5228-5241. [PMID: 27460507 PMCID: PMC5082504 DOI: 10.1111/mec.13769] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2015] [Revised: 07/03/2016] [Accepted: 07/05/2016] [Indexed: 12/18/2022]
Abstract
Variation in susceptibility to infection has a substantial genetic component in natural populations, and it has been argued that selection by pathogens may result in it having a simpler genetic architecture than many other quantitative traits. This is important as models of host-pathogen co-evolution typically assume resistance is controlled by a small number of genes. Using the Drosophila melanogaster multiparent advanced intercross, we investigated the genetic architecture of resistance to two naturally occurring viruses, the sigma virus and DCV (Drosophila C virus). We found extensive genetic variation in resistance to both viruses. For DCV resistance, this variation is largely caused by two major-effect loci. Sigma virus resistance involves more genes - we mapped five loci, and together these explained less than half the genetic variance. Nonetheless, several of these had a large effect on resistance. Models of co-evolution typically assume strong epistatic interactions between polymorphisms controlling resistance, but we were only able to detect one locus that altered the effect of the main effect loci we had mapped. Most of the loci we mapped were probably at an intermediate frequency in natural populations. Overall, our results are consistent with major-effect genes commonly affecting susceptibility to infectious diseases, with DCV resistance being a near-Mendelian trait.
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Affiliation(s)
- Rodrigo Cogni
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK.
- Department of Ecology, University of São Paulo, São Paulo, 05508-900, Brazil.
| | - Chuan Cao
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Calum Bridson
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH, UK
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29
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Hoy MA, Waterhouse RM, Wu K, Estep AS, Ioannidis P, Palmer WJ, Pomerantz AF, Simão FA, Thomas J, Jiggins FM, Murphy TD, Pritham EJ, Robertson HM, Zdobnov EM, Gibbs RA, Richards S. Genome Sequencing of the Phytoseiid Predatory Mite Metaseiulus occidentalis Reveals Completely Atomized Hox Genes and Superdynamic Intron Evolution. Genome Biol Evol 2016; 8:1762-75. [PMID: 26951779 PMCID: PMC4943173 DOI: 10.1093/gbe/evw048] [Citation(s) in RCA: 78] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/27/2016] [Indexed: 12/16/2022] Open
Abstract
Metaseiulus occidentalis is an eyeless phytoseiid predatory mite employed for the biological control of agricultural pests including spider mites. Despite appearances, these predator and prey mites are separated by some 400 Myr of evolution and radically different lifestyles. We present a 152-Mb draft assembly of the M. occidentalis genome: Larger than that of its favored prey, Tetranychus urticae, but considerably smaller than those of many other chelicerates, enabling an extremely contiguous and complete assembly to be built-the best arachnid to date. Aided by transcriptome data, genome annotation cataloged 18,338 protein-coding genes and identified large numbers of Helitron transposable elements. Comparisons with other arthropods revealed a particularly dynamic and turbulent genomic evolutionary history. Its genes exhibit elevated molecular evolution, with strikingly high numbers of intron gains and losses, in stark contrast to the deer tick Ixodes scapularis Uniquely among examined arthropods, this predatory mite's Hox genes are completely atomized, dispersed across the genome, and it encodes five copies of the normally single-copy RNA processing Dicer-2 gene. Examining gene families linked to characteristic biological traits of this tiny predator provides initial insights into processes of sex determination, development, immune defense, and how it detects, disables, and digests its prey. As the first reference genome for the Phytoseiidae, and for any species with the rare sex determination system of parahaploidy, the genome of the western orchard predatory mite improves genomic sampling of chelicerates and provides invaluable new resources for functional genomic analyses of this family of agriculturally important mites.
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Affiliation(s)
- Marjorie A Hoy
- Department of Entomology and Nematology, University of Florida
| | - Robert M Waterhouse
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland Computer Science and Artificial Intelligence Laboratory, Massachusetts Institute of Technology The Broad Institute of MIT and Harvard, Cambridge, Massachusetts
| | - Ke Wu
- Department of Entomology and Nematology, University of Florida
| | - Alden S Estep
- Department of Entomology and Nematology, University of Florida
| | - Panagiotis Ioannidis
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland
| | | | | | - Felipe A Simão
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Jainy Thomas
- Department of Human Genetics, University of Utah
| | | | - Terence D Murphy
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, Maryland
| | | | - Hugh M Robertson
- Department of Entomology, University of Illinois at Urbana-Champaign
| | - Evgeny M Zdobnov
- Department of Genetic Medicine and Development, University of Geneva Medical School, Switzerland Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Richard A Gibbs
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine
| | - Stephen Richards
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine
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30
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Cao C, Magwire MM, Bayer F, Jiggins FM. Correction: A Polymorphism in the Processing Body Component Ge-1 Controls Resistance to a Naturally Occurring Rhabdovirus in Drosophila. PLoS Pathog 2016; 12:e1005730. [PMID: 27322179 PMCID: PMC4913908 DOI: 10.1371/journal.ppat.1005730] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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31
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Rainey SM, Martinez J, McFarlane M, Juneja P, Sarkies P, Lulla A, Schnettler E, Varjak M, Merits A, Miska EA, Jiggins FM, Kohl A. Wolbachia Blocks Viral Genome Replication Early in Infection without a Transcriptional Response by the Endosymbiont or Host Small RNA Pathways. PLoS Pathog 2016; 12:e1005536. [PMID: 27089431 PMCID: PMC4835223 DOI: 10.1371/journal.ppat.1005536] [Citation(s) in RCA: 61] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2015] [Accepted: 03/09/2016] [Indexed: 12/22/2022] Open
Abstract
The intracellular endosymbiotic bacterium Wolbachia can protect insects against viral infection, and is being introduced into mosquito populations in the wild to block the transmission of arboviruses that infect humans and are a major public health concern. To investigate the mechanisms underlying this antiviral protection, we have developed a new model system combining Wolbachia-infected Drosophila melanogaster cell culture with the model mosquito-borne Semliki Forest virus (SFV; Togaviridae, Alphavirus). Wolbachia provides strong antiviral protection rapidly after infection, suggesting that an early stage post-infection is being blocked. Wolbachia does appear to have major effects on events distinct from entry, assembly or exit as it inhibits the replication of an SFV replicon transfected into the cells. Furthermore, it causes a far greater reduction in the expression of proteins from the 3´ open reading frame than the 5´ non-structural protein open reading frame, indicating that it is blocking the replication of viral RNA. Further to this separation of the replicase proteins and viral RNA in transreplication assays shows that uncoupling of viral RNA and replicase proteins does not overcome Wolbachia’s antiviral activity. This further suggests that replicative processes are disrupted, such as translation or replication, by Wolbachia infection. This may occur by Wolbachia mounting an active antiviral response, but the virus did not cause any transcriptional response by the bacterium, suggesting that this is not the case. Host microRNAs (miRNAs) have been implicated in protection, but again we found that host cell miRNA expression was unaffected by the bacterium and neither do our findings suggest any involvement of the antiviral siRNA pathway. We conclude that Wolbachia may directly interfere with early events in virus replication such as translation of incoming viral RNA or RNA transcription, and this likely involves an intrinsic (as opposed to an induced) mechanism. The intracellular endosymbiotic bacterium Wolbachia can protect insects against viral infection. However, the mechanisms underlying this antiviral activity are poorly understood. We have developed a new model system combining Wolbachia-infected Drosophila melanogaster cell culture and the model mosquito-borne virus, Semliki Forest virus. Wolbachia confers strong antiviral activity against SFV. Our study indicates that viral replication appears to be inhibited at a very early stage, such as initial translation or replication. Results indicate that Wolbachia does not mount a transcriptional response to SFV infection and that host small RNA pathways are not involved in Wolbachia mediated antiviral activity in our system. We conclude that Wolbachia may directly interfere with early events in virus replication such as translation of incoming viral RNA or RNA transcription, and this likely involves an intrinsic (as opposed to an induced) mechanism.
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Affiliation(s)
- Stephanie M. Rainey
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Melanie McFarlane
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Peter Sarkies
- MRC Clinical Sciences Centre, Imperial College London, London, United Kingdom
| | - Aleksei Lulla
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Esther Schnettler
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Margus Varjak
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
| | - Andres Merits
- Institute of Technology, University of Tartu, Tartu, Estonia
| | - Eric A. Miska
- Gurdon Institute and Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- * E-mail: (AK); (FMJ)
| | - Alain Kohl
- MRC-University of Glasgow Centre for Virus Research, Glasgow, Scotland, United Kingdom
- * E-mail: (AK); (FMJ)
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Palmer WJ, Duarte A, Schrader M, Day JP, Kilner R, Jiggins FM. A gene associated with social immunity in the burying beetle Nicrophorus vespilloides. Proc Biol Sci 2016; 283:rspb.2015.2733. [PMID: 26817769 PMCID: PMC4795035 DOI: 10.1098/rspb.2015.2733] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 01/05/2016] [Indexed: 12/02/2022] Open
Abstract
Some group-living species exhibit social immunity, where the immune response of one individual can protect others in the group from infection. In burying beetles, this is part of parental care. Larvae feed on vertebrate carcasses which their parents smear with exudates that inhibit microbial growth. We have sequenced the transcriptome of the burying beetle Nicrophorus vespilloides and identified six genes that encode lysozymes—a type of antimicrobial enzyme that has previously been implicated in social immunity in burying beetles. When females start breeding and producing antimicrobial anal exudates, we found that the expression of one of these genes was increased by approximately 1000 times to become one of the most abundant transcripts in the transcriptome. Females varied considerably in the antimicrobial properties of their anal exudates, and this was strongly correlated with the expression of this lysozyme. We conclude that we have likely identified a gene encoding a key effector molecule in social immunity and that it was recruited during evolution from a function in personal immunity.
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Affiliation(s)
| | - Ana Duarte
- Department of Zoology, University of Cambridge, Cambridge, UK
| | | | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, UK
| | - Rebecca Kilner
- Department of Zoology, University of Cambridge, Cambridge, UK
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33
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Cao C, Magwire MM, Bayer F, Jiggins FM. A Polymorphism in the Processing Body Component Ge-1 Controls Resistance to a Naturally Occurring Rhabdovirus in Drosophila. PLoS Pathog 2016; 12:e1005387. [PMID: 26799957 PMCID: PMC4723093 DOI: 10.1371/journal.ppat.1005387] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2015] [Accepted: 12/17/2015] [Indexed: 12/30/2022] Open
Abstract
Hosts encounter an ever-changing array of pathogens, so there is continual selection for novel ways to resist infection. A powerful way to understand how hosts evolve resistance is to identify the genes that cause variation in susceptibility to infection. Using high-resolution genetic mapping we have identified a naturally occurring polymorphism in a gene called Ge-1 that makes Drosophila melanogaster highly resistant to its natural pathogen Drosophila melanogaster sigma virus (DMelSV). By modifying the sequence of the gene in transgenic flies, we identified a 26 amino acid deletion in the serine-rich linker region of Ge-1 that is causing the resistance. Knocking down the expression of the susceptible allele leads to a decrease in viral titre in infected flies, indicating that Ge-1 is an existing restriction factor whose antiviral effects have been increased by the deletion. Ge-1 plays a central role in RNA degradation and the formation of processing bodies (P bodies). A key effector in antiviral immunity, the RNAi induced silencing complex (RISC), localises to P bodies, but we found that Ge-1-based resistance is not dependent on the small interfering RNA (siRNA) pathway. However, we found that Decapping protein 1 (DCP1) protects flies against sigma virus. This protein interacts with Ge-1 and commits mRNA for degradation by removing the 5’ cap, suggesting that resistance may rely on this RNA degradation pathway. The serine-rich linker domain of Ge-1 has experienced strong selection during the evolution of Drosophila, suggesting that this gene may be under long-term selection by viruses. These findings demonstrate that studying naturally occurring polymorphisms that increase resistance to infections enables us to identify novel forms of antiviral defence, and support a pattern of major effect polymorphisms controlling resistance to viruses in Drosophila. Hosts and their pathogens are engaged in a never-ending arms race, and hosts must continually evolve new defences to protect themselves from infection. In the fruit fly Drosophila melanogaster we show that virus resistance can evolve through a single mutation. In flies that are highly resistant to a naturally occurring virus called sigma virus we identified a deletion in the protein-coding region of a gene called Ge-1. We experimentally confirmed that this was the cause of resistance by deleting this region in transgenic flies. Furthermore, we show that even the susceptible allele of Ge-1 helps protect flies against the virus, suggesting that this mutation has made an existing antiviral defence more effective. Ge-1 plays a central role in RNA degradation in regions of the cytoplasm called P bodies, and our results suggest that this pathway has been recruited during evolution to protect D. melanogaster against sigma virus. The protein domain that contains the deletion has experienced strong selection during its evolution, suggesting that it may be involved in an ongoing arms race with viruses.
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Affiliation(s)
- Chuan Cao
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| | - Michael M. Magwire
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Florian Bayer
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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34
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Longdon B, Murray GGR, Palmer WJ, Day JP, Parker DJ, Welch JJ, Obbard DJ, Jiggins FM. The evolution, diversity, and host associations of rhabdoviruses. Virus Evol 2015; 1:vev014. [PMID: 27774286 PMCID: PMC5014481 DOI: 10.1093/ve/vev014] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Metagenomic studies are leading to the discovery of a hidden diversity of RNA viruses. These new viruses are poorly characterized and new approaches are needed predict the host species these viruses pose a risk to. The rhabdoviruses are a diverse family of RNA viruses that includes important pathogens of humans, animals, and plants. We have discovered thirty-two new rhabdoviruses through a combination of our own RNA sequencing of insects and searching public sequence databases. Combining these with previously known sequences we reconstructed the phylogeny of 195 rhabdovirus sequences, and produced the most in depth analysis of the family to date. In most cases we know nothing about the biology of the viruses beyond the host they were identified from, but our dataset provides a powerful phylogenetic approach to predict which are vector-borne viruses and which are specific to vertebrates or arthropods. By reconstructing ancestral and present host states we found that switches between major groups of hosts have occurred rarely during rhabdovirus evolution. This allowed us to propose seventy-six new likely vector-borne vertebrate viruses among viruses identified from vertebrates or biting insects. Based on currently available data, our analysis suggests it is likely there was a single origin of the known plant viruses and arthropod-borne vertebrate viruses, while vertebrate- and arthropod-specific viruses arose at least twice. There are also few transitions between aquatic and terrestrial ecosystems. Viruses also cluster together at a finer scale, with closely related viruses tending to be found in closely related hosts. Our data therefore suggest that throughout their evolution, rhabdoviruses have occasionally jumped between distantly related host species before spreading through related hosts in the same environment. This approach offers a way to predict the most probable biology and key traits of newly discovered viruses.
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Affiliation(s)
- Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH
| | - Gemma G R Murray
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH
| | - William J Palmer
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH
| | - Darren J Parker
- School of Biology, University of St Andrews, St Andrews, KY19 9ST, UK,; Department of Biological and Environmental Science, University of Jyväskylä, Jyväskylä, Finland and
| | - John J Welch
- Department of Genetics, University of Cambridge, Cambridge, CB2 3EH
| | - Darren J Obbard
- Institute of Evolutionary Biology, and Centre for Immunity Infection and Evolution, University of Edinburgh, Edinburgh, EH9 3JT, UK
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Abstract
Insects are an important model for the study of innate immune systems, but remarkably little is known about the immune system of other arthropod groups despite their importance as disease vectors, pests, and components of biological diversity. Using comparative genomics, we have characterized the immune system of all the major groups of arthropods beyond insects for the first time--studying five chelicerates, a myriapod, and a crustacean. We found clear traces of an ancient origin of innate immunity, with some arthropods having Toll-like receptors and C3-complement factors that are more closely related in sequence or structure to vertebrates than other arthropods. Across the arthropods some components of the immune system, such as the Toll signaling pathway, are highly conserved. However, there is also remarkable diversity. The chelicerates apparently lack the Imd signaling pathway and beta-1,3 glucan binding proteins--a key class of pathogen recognition receptors. Many genes have large copy number variation across species, and this may sometimes be accompanied by changes in function. For example, we find that peptidoglycan recognition proteins have frequently lost their catalytic activity and switch between secreted and intracellular forms. We also find that there has been widespread and extensive duplication of the cellular immune receptor Dscam (Down syndrome cell adhesion molecule), which may be an alternative way to generate the high diversity produced by alternative splicing in insects. In the antiviral short interfering RNAi pathway Argonaute 2 evolves rapidly and is frequently duplicated, with a highly variable copy number. Our results provide a detailed analysis of the immune systems of several important groups of animals for the first time and lay the foundations for functional work on these groups.
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Affiliation(s)
- William J Palmer
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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36
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Martinez J, Ok S, Smith S, Snoeck K, Day JP, Jiggins FM. Should Symbionts Be Nice or Selfish? Antiviral Effects of Wolbachia Are Costly but Reproductive Parasitism Is Not. PLoS Pathog 2015; 11:e1005021. [PMID: 26132467 PMCID: PMC4488530 DOI: 10.1371/journal.ppat.1005021] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2015] [Accepted: 06/11/2015] [Indexed: 12/20/2022] Open
Abstract
Symbionts can have mutualistic effects that increase their host's fitness and/or parasitic effects that reduce it. Which of these strategies evolves depends in part on the balance of their costs and benefits to the symbiont. We have examined these questions in Wolbachia, a vertically transmitted endosymbiont of insects that can provide protection against viral infection and/or parasitically manipulate its hosts' reproduction. Across multiple symbiont strains we find that the parasitic phenotype of cytoplasmic incompatibility and antiviral protection are uncorrelated. Strong antiviral protection is associated with substantial reductions in other fitness-related traits, whereas no such trade-off was detected for cytoplasmic incompatibility. The reason for this difference is likely that antiviral protection requires high symbiont densities but cytoplasmic incompatibility does not. These results are important for the use of Wolbachia to block dengue virus transmission by mosquitoes, as natural selection to reduce these costs may lead to reduced symbiont density and the loss of antiviral protection.
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Affiliation(s)
- Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Suzan Ok
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Sophie Smith
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Kiana Snoeck
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jon P. Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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37
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Juneja P, Ariani CV, Ho YS, Akorli J, Palmer WJ, Pain A, Jiggins FM. Exome and transcriptome sequencing of Aedes aegypti identifies a locus that confers resistance to Brugia malayi and alters the immune response. PLoS Pathog 2015; 11:e1004765. [PMID: 25815506 PMCID: PMC4376896 DOI: 10.1371/journal.ppat.1004765] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Accepted: 02/25/2015] [Indexed: 11/18/2022] Open
Abstract
Many mosquito species are naturally polymorphic for their abilities to transmit parasites, a feature which is of great interest for controlling vector-borne disease. Aedes aegypti, the primary vector of dengue and yellow fever and a laboratory model for studying lymphatic filariasis, is genetically variable for its capacity to harbor the filarial nematode Brugia malayi. The genome of Ae. aegypti is large and repetitive, making genome resequencing difficult and expensive. We designed exome captures to target protein-coding regions of the genome, and used association mapping in a wild Kenyan population to identify a single, dominant, sex-linked locus underlying resistance. This falls in a region of the genome where a resistance locus was previously mapped in a line established in 1936, suggesting that this polymorphism has been maintained in the wild for the at least 80 years. We then crossed resistant and susceptible mosquitoes to place both alleles of the gene into a common genetic background, and used RNA-seq to measure the effect of this locus on gene expression. We found evidence for Toll, IMD, and JAK-STAT pathway activity in response to early stages of B. malayi infection when the parasites are beginning to die in the resistant genotype. We also found that resistant mosquitoes express anti-microbial peptides at the time of parasite-killing, and that this expression is suppressed in susceptible mosquitoes. Together, we have found that a single resistance locus leads to a higher immune response in resistant mosquitoes, and we identify genes in this region that may be responsible for this trait.
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Affiliation(s)
- Punita Juneja
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Cristina V. Ariani
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Yung Shwen Ho
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science & Technology, Thuwal, Kingdom of Saudi Arabia
| | - Jewelna Akorli
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- Department of Parasitology, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - William J. Palmer
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Arnab Pain
- Biological and Environmental Sciences and Engineering (BESE) Division, King Abdullah University of Science & Technology, Thuwal, Kingdom of Saudi Arabia
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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38
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Longdon B, Hadfield JD, Day JP, Smith SCL, McGonigle JE, Cogni R, Cao C, Jiggins FM. The causes and consequences of changes in virulence following pathogen host shifts. PLoS Pathog 2015; 11:e1004728. [PMID: 25774803 PMCID: PMC4361674 DOI: 10.1371/journal.ppat.1004728] [Citation(s) in RCA: 87] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 02/04/2015] [Indexed: 11/19/2022] Open
Abstract
Emerging infectious diseases are often the result of a host shift, where the pathogen originates from a different host species. Virulence--the harm a pathogen does to its host-can be extremely high following a host shift (for example Ebola, HIV, and SARs), while other host shifts may go undetected as they cause few symptoms in the new host. Here we examine how virulence varies across host species by carrying out a large cross infection experiment using 48 species of Drosophilidae and an RNA virus. Host shifts resulted in dramatic variation in virulence, with benign infections in some species and rapid death in others. The change in virulence was highly predictable from the host phylogeny, with hosts clustering together in distinct clades displaying high or low virulence. High levels of virulence are associated with high viral loads, and this may determine the transmission rate of the virus.
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Affiliation(s)
- Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jarrod D Hadfield
- Institute of Evolutionary Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Jonathan P Day
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Sophia C L Smith
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - John E McGonigle
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Rodrigo Cogni
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom; Department of Ecology, University of São Paulo, São Paulo, Brazil
| | - Chuan Cao
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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39
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Ahmed MZ, Li SJ, Xue X, Yin XJ, Ren SX, Jiggins FM, Greeff JM, Qiu BL. The intracellular bacterium Wolbachia uses parasitoid wasps as phoretic vectors for efficient horizontal transmission. PLoS Pathog 2015; 10:e1004672. [PMID: 25675099 PMCID: PMC4347858 DOI: 10.1371/journal.ppat.1004672] [Citation(s) in RCA: 108] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2014] [Accepted: 01/08/2015] [Indexed: 11/18/2022] Open
Abstract
Facultative bacterial endosymbionts are associated with many arthropods and are primarily transmitted vertically from mother to offspring. However, phylogenetic affiliations suggest that horizontal transmission must also occur. Such horizontal transfer can have important biological and agricultural consequences when endosymbionts increase host fitness. So far horizontal transmission is considered rare and has been difficult to document. Here, we use fluorescence in situ hybridization (FISH) and multi locus sequence typing (MLST) to reveal a potentially common pathway of horizontal transmission of endosymbionts via parasitoids of insects. We illustrate that the mouthparts and ovipositors of an aphelinid parasitoid become contaminated with Wolbachia when this wasp feeds on or probes Wolbachia-infected Bemisia tabaci AsiaII7, and non-lethal probing of uninfected B. tabaci AsiaII7 nymphs by parasitoids carrying Wolbachia resulted in newly and stably infected B. tabaci matrilines. After they were exposed to infected whitefly, the parasitoids were able to transmit Wolbachia efficiently for the following 48 h. Whitefly infected with Wolbachia by parasitoids had increased survival and reduced development times. Overall, our study provides evidence for the horizontal transmission of Wolbachia between insect hosts by parasitic wasps, and the enhanced survival and reproductive abilities of insect hosts may adversely affect biological control programs.
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Affiliation(s)
- Muhammad Z. Ahmed
- Department of Entomology, South China Agricultural University, Guangzhou, China
- Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Shao-Jian Li
- Department of Entomology, South China Agricultural University, Guangzhou, China
| | - Xia Xue
- Department of Entomology, South China Agricultural University, Guangzhou, China
| | - Xiang-Jie Yin
- Department of Entomology, South China Agricultural University, Guangzhou, China
| | - Shun-Xiang Ren
- Department of Entomology, South China Agricultural University, Guangzhou, China
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jaco M. Greeff
- Department of Genetics, University of Pretoria, Pretoria, South Africa
| | - Bao-Li Qiu
- Department of Entomology, South China Agricultural University, Guangzhou, China
- * E-mail:
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40
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Ariani CV, Smith SCL, Osei-Poku J, Short K, Juneja P, Jiggins FM. Environmental and genetic factors determine whether the mosquito Aedes aegypti lays eggs without a blood meal. Am J Trop Med Hyg 2015; 92:715-21. [PMID: 25646251 DOI: 10.4269/ajtmh.14-0471] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 11/20/2014] [Indexed: 11/07/2022] Open
Abstract
Some mosquito strains or species are able to lay eggs without taking a blood meal, a trait named autogeny. This may allow populations to persist through times or places where vertebrate hosts are scarce. Autogenous egg production is highly dependent on the environment in some species, but the ideal conditions for its expression in Aedes aegypti mosquitoes are unknown. We found that 3.2% of females in a population of Ae. aegypti from Kenya were autogenous. Autogeny was strongly influenced by temperature, with many more eggs laid at 28°C compared with 22°C. Good nutrition in larval stages and feeding on higher concentrations of sugar solution during the adult stage both result in more autogenous eggs being produced. The trait also has a genetic basis, as not all Ae. aegypti genotypes can lay autogenously. We conclude that Ae. aegypti requires a favorable environment and a suitable genotype to be able to lay eggs without a blood meal.
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Affiliation(s)
- Cristina V Ariani
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Sophia C L Smith
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Jewelna Osei-Poku
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Katherine Short
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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41
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Chipman AD, Ferrier DEK, Brena C, Qu J, Hughes DST, Schröder R, Torres-Oliva M, Znassi N, Jiang H, Almeida FC, Alonso CR, Apostolou Z, Aqrawi P, Arthur W, Barna JCJ, Blankenburg KP, Brites D, Capella-Gutiérrez S, Coyle M, Dearden PK, Du Pasquier L, Duncan EJ, Ebert D, Eibner C, Erikson G, Evans PD, Extavour CG, Francisco L, Gabaldón T, Gillis WJ, Goodwin-Horn EA, Green JE, Griffiths-Jones S, Grimmelikhuijzen CJP, Gubbala S, Guigó R, Han Y, Hauser F, Havlak P, Hayden L, Helbing S, Holder M, Hui JHL, Hunn JP, Hunnekuhl VS, Jackson L, Javaid M, Jhangiani SN, Jiggins FM, Jones TE, Kaiser TS, Kalra D, Kenny NJ, Korchina V, Kovar CL, Kraus FB, Lapraz F, Lee SL, Lv J, Mandapat C, Manning G, Mariotti M, Mata R, Mathew T, Neumann T, Newsham I, Ngo DN, Ninova M, Okwuonu G, Ongeri F, Palmer WJ, Patil S, Patraquim P, Pham C, Pu LL, Putman NH, Rabouille C, Ramos OM, Rhodes AC, Robertson HE, Robertson HM, Ronshaugen M, Rozas J, Saada N, Sánchez-Gracia A, Scherer SE, Schurko AM, Siggens KW, Simmons D, Stief A, Stolle E, Telford MJ, Tessmar-Raible K, Thornton R, van der Zee M, von Haeseler A, Williams JM, Willis JH, Wu Y, Zou X, Lawson D, Muzny DM, Worley KC, Gibbs RA, Akam M, Richards S. The first myriapod genome sequence reveals conservative arthropod gene content and genome organisation in the centipede Strigamia maritima. PLoS Biol 2014; 12:e1002005. [PMID: 25423365 PMCID: PMC4244043 DOI: 10.1371/journal.pbio.1002005] [Citation(s) in RCA: 176] [Impact Index Per Article: 17.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2014] [Accepted: 10/15/2014] [Indexed: 12/14/2022] Open
Abstract
Myriapods (e.g., centipedes and millipedes) display a simple homonomous body plan relative to other arthropods. All members of the class are terrestrial, but they attained terrestriality independently of insects. Myriapoda is the only arthropod class not represented by a sequenced genome. We present an analysis of the genome of the centipede Strigamia maritima. It retains a compact genome that has undergone less gene loss and shuffling than previously sequenced arthropods, and many orthologues of genes conserved from the bilaterian ancestor that have been lost in insects. Our analysis locates many genes in conserved macro-synteny contexts, and many small-scale examples of gene clustering. We describe several examples where S. maritima shows different solutions from insects to similar problems. The insect olfactory receptor gene family is absent from S. maritima, and olfaction in air is likely effected by expansion of other receptor gene families. For some genes S. maritima has evolved paralogues to generate coding sequence diversity, where insects use alternate splicing. This is most striking for the Dscam gene, which in Drosophila generates more than 100,000 alternate splice forms, but in S. maritima is encoded by over 100 paralogues. We see an intriguing linkage between the absence of any known photosensory proteins in a blind organism and the additional absence of canonical circadian clock genes. The phylogenetic position of myriapods allows us to identify where in arthropod phylogeny several particular molecular mechanisms and traits emerged. For example, we conclude that juvenile hormone signalling evolved with the emergence of the exoskeleton in the arthropods and that RR-1 containing cuticle proteins evolved in the lineage leading to Mandibulata. We also identify when various gene expansions and losses occurred. The genome of S. maritima offers us a unique glimpse into the ancestral arthropod genome, while also displaying many adaptations to its specific life history. Arthropods are the most abundant animals on earth. Among them, insects clearly dominate on land, whereas crustaceans hold the title for the most diverse invertebrates in the oceans. Much is known about the biology of these groups, not least because of genomic studies of the fruit fly Drosophila, the water flea Daphnia, and other species used in research. Here we report the first genome sequence from a species belonging to a lineage that has previously received very little attention—the myriapods. Myriapods were among the first arthropods to invade the land over 400 million years ago, and survive today as the herbivorous millipedes and venomous centipedes, one of which—Strigamia maritima—we have sequenced here. We find that the genome of this centipede retains more characteristics of the presumed arthropod ancestor than other sequenced insect genomes. The genome provides access to many aspects of myriapod biology that have not been studied before, suggesting, for example, that they have diversified receptors for smell that are quite different from those used by insects. In addition, it shows specific consequences of the largely subterranean life of this particular species, which seems to have lost the genes for all known light-sensing molecules, even though it still avoids light.
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Affiliation(s)
- Ariel D. Chipman
- The Department of Ecology, Evolution and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Givat Ram, Jerusalem, Israel
| | - David E. K. Ferrier
- The Scottish Oceans Institute, Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Carlo Brena
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Jiaxin Qu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Daniel S. T. Hughes
- EMBL - European Bioinformatics Institute, Hinxton, Cambridgeshire, United Kingdom
| | - Reinhard Schröder
- Institut für Biowissenschaften, Universität Rostock, Abt. Genetik, Rostock, Germany
| | | | - Nadia Znassi
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Huaiyang Jiang
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Francisca C. Almeida
- Departament de Genètica and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
- Consejo Nacional de Investigaciones Científicas y Tecnológicas (CONICET), Universidad Nacional de Tucumán, Facultad de Ciencias Naturales e Instituto Miguel Lillo, San Miguel de Tucumán, Argentina
| | - Claudio R. Alonso
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Zivkos Apostolou
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Institute of Molecular Biology & Biotechnology, Foundation for Research & Technology - Hellas, Heraklion, Crete, Greece
| | - Peshtewani Aqrawi
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Wallace Arthur
- Department of Zoology, National University of Ireland, Galway, Ireland
| | | | - Kerstin P. Blankenburg
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Daniela Brites
- Evolutionsbiologie, Zoologisches Institut, Universität Basel, Basel, Switzerland
- Swiss Tropical and Public Health Institute, Basel, Switzerland
| | | | - Marcus Coyle
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Peter K. Dearden
- Gravida and Genetics Otago, Biochemistry Department, University of Otago, Dunedin, New Zealand
| | - Louis Du Pasquier
- Evolutionsbiologie, Zoologisches Institut, Universität Basel, Basel, Switzerland
| | - Elizabeth J. Duncan
- Gravida and Genetics Otago, Biochemistry Department, University of Otago, Dunedin, New Zealand
| | - Dieter Ebert
- Evolutionsbiologie, Zoologisches Institut, Universität Basel, Basel, Switzerland
| | - Cornelius Eibner
- Department of Zoology, National University of Ireland, Galway, Ireland
| | - Galina Erikson
- Razavi Newman Center for Bioinformatics, Salk Institute, La Jolla, California, United States of America
- Scripps Translational Science Institute, La Jolla, California, United States of America
| | | | - Cassandra G. Extavour
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Liezl Francisco
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Toni Gabaldón
- Centre for Genomic Regulation, Barcelona, Barcelona, Spain
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Barcelona, Spain
| | - William J. Gillis
- Department of Biochemistry and Cell Biology, Center for Developmental Genetics, Stony Brook University, Stony Brook, New York, United States of America
| | | | - Jack E. Green
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Sam Griffiths-Jones
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | | | - Sai Gubbala
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Roderic Guigó
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Center for Genomic Regulation, Barcelona, Spain
| | - Yi Han
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Frank Hauser
- Center for Functional and Comparative Insect Genomics, University of Copenhagen, Copenhagen, Denmark
| | - Paul Havlak
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America
| | - Luke Hayden
- Department of Zoology, National University of Ireland, Galway, Ireland
| | - Sophie Helbing
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - Michael Holder
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jerome H. L. Hui
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Julia P. Hunn
- Department of Biochemistry and Cell Biology, Faculty of Veterinary Medicine, Utrecht University, Utrecht, The Netherlands
| | - Vera S. Hunnekuhl
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - LaRonda Jackson
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Mehwish Javaid
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Shalini N. Jhangiani
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Tamsin E. Jones
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Tobias S. Kaiser
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
| | - Divya Kalra
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Nathan J. Kenny
- School of Life Sciences, The Chinese University of Hong Kong, Shatin, NT, Hong Kong SAR, China
| | - Viktoriya Korchina
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Christie L. Kovar
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - F. Bernhard Kraus
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
- Department of Laboratory Medicine, University Hospital Halle (Saale), Halle (Saale), Germany
| | - François Lapraz
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Sandra L. Lee
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Jie Lv
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America
| | - Christigale Mandapat
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Gerard Manning
- Razavi Newman Center for Bioinformatics, Salk Institute, La Jolla, California, United States of America
| | - Marco Mariotti
- Universitat Pompeu Fabra (UPF), Barcelona, Spain
- Center for Genomic Regulation, Barcelona, Spain
| | - Robert Mata
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tittu Mathew
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Tobias Neumann
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, Vienna, Austria
| | - Irene Newsham
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Dinh N. Ngo
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Maria Ninova
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Geoffrey Okwuonu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Fiona Ongeri
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - William J. Palmer
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Shobha Patil
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Pedro Patraquim
- School of Life Sciences, University of Sussex, Brighton, United Kingdom
| | - Christopher Pham
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Ling-Ling Pu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Nicholas H. Putman
- Department of Ecology and Evolutionary Biology, Rice University, Houston, Texas, United States of America
| | - Catherine Rabouille
- Hubrecht Institute for Developmental Biology and Stem Cell Research, Utrecht, The Netherlands
| | - Olivia Mendivil Ramos
- The Scottish Oceans Institute, Gatty Marine Laboratory, University of St Andrews, St Andrews, Fife, United Kingdom
| | - Adelaide C. Rhodes
- Harte Research Institute, Texas A&M University Corpus Christi, Corpus Christi, Texas, United States of America
| | - Helen E. Robertson
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Hugh M. Robertson
- Department of Entomology, University of Illinois at Urbana-Champaign, Urbana, Illinois, United States of America
| | - Matthew Ronshaugen
- Faculty of Life Sciences, University of Manchester, Manchester, United Kingdom
| | - Julio Rozas
- Departament de Genètica and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - Nehad Saada
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Alejandro Sánchez-Gracia
- Departament de Genètica and Institut de Recerca de la Biodiversitat (IRBio), Universitat de Barcelona, Barcelona, Spain
| | - Steven E. Scherer
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Andrew M. Schurko
- Department of Biology, Hendrix College, Conway, Arkansas, United States of America
| | - Kenneth W. Siggens
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - DeNard Simmons
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Anna Stief
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
- Institute for Biochemistry and Biology, University Potsdam, Potsdam-Golm, Germany
| | - Eckart Stolle
- Institut für Biologie, Martin-Luther-Universität Halle-Wittenberg, Halle, Germany
| | - Maximilian J. Telford
- Department of Genetics, Evolution and Environment, University College London, London, United Kingdom
| | - Kristin Tessmar-Raible
- Max F. Perutz Laboratories, University of Vienna, Vienna, Austria
- Research Platform “Marine Rhythms of Life”, Vienna, Austria
| | - Rebecca Thornton
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | | | - Arndt von Haeseler
- Center for Integrative Bioinformatics Vienna, Max F. Perutz Laboratories, University of Vienna, Medical University of Vienna, Vienna, Austria
- Bioinformatics and Computational Biology, Faculty of Computer Science, University of Vienna, Vienna, Austria
| | - James M. Williams
- Department of Biology, Hendrix College, Conway, Arkansas, United States of America
| | - Judith H. Willis
- Department of Cellular Biology, University of Georgia, Athens, Georgia, United States of America
| | - Yuanqing Wu
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Xiaoyan Zou
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Daniel Lawson
- EMBL - European Bioinformatics Institute, Hinxton, Cambridgeshire, United Kingdom
| | - Donna M. Muzny
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Kim C. Worley
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Richard A. Gibbs
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
| | - Michael Akam
- Department of Zoology, University of Cambridge, Cambridge, United Kingdom
| | - Stephen Richards
- Human Genome Sequencing Center, Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, United States of America
- * E-mail:
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Ariani CV, Juneja P, Smith S, Tinsley MC, Jiggins FM. Vector competence of Aedes aegypti mosquitoes for filarial nematodes is affected by age and nutrient limitation. Exp Gerontol 2014; 61:47-53. [PMID: 25446985 DOI: 10.1016/j.exger.2014.11.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2014] [Revised: 10/27/2014] [Accepted: 11/02/2014] [Indexed: 10/24/2022]
Abstract
Mosquitoes are one of the most important vectors of human disease. The ability of mosquitoes to transmit disease is dependent on the age structure of the population, as mosquitoes must survive long enough for the parasites to complete their development and infect another human. Age could have additional effects due to mortality rates and vector competence changing as mosquitoes senesce, but these are comparatively poorly understood. We have investigated these factors using the mosquito Aedes aegypti and the filarial nematode Brugia malayi. Rather than observing any effects of immune senescence, we found that older mosquitoes were more resistant, but this only occurred if they had previously been maintained on a nutrient-poor diet of fructose. Constant blood feeding reversed this decline in vector competence, meaning that the number of parasites remained relatively unchanged as mosquitoes aged. Old females that had been maintained on fructose also experienced a sharp spike in mortality after an infected blood meal ("refeeding syndrome") and few survived long enough for the parasite to develop. Again, this effect was prevented by frequent blood meals. Our results indicate that old mosquitoes may be inefficient vectors due to low vector competence and high mortality, but that frequent blood meals can prevent these effects of age.
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Affiliation(s)
- Cristina V Ariani
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom.
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom.
| | - Sophia Smith
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom.
| | - Matthew C Tinsley
- Biological and Environmental Sciences, University of Stirling, Stirling FK9 4LA, United Kingdom.
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB24 6BG, United Kingdom.
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Abstract
Emerging viral diseases are often the product of a host shift, where a pathogen jumps from its original host into a novel species. Phylogenetic studies show that host shifts are a frequent event in the evolution of most pathogens, but why pathogens successfully jump between some host species but not others is only just becoming clear. The susceptibility of potential new hosts can vary enormously, with close relatives of the natural host typically being the most susceptible. Often, pathogens must adapt to successfully infect a novel host, for example by evolving to use different cell surface receptors, to escape the immune response, or to ensure they are transmitted by the new host. In viruses there are often limited molecular solutions to achieve this, and the same sequence changes are often seen each time a virus infects a particular host. These changes may come at a cost to other aspects of the pathogen's fitness, and this may sometimes prevent host shifts from occurring. Here we examine how these evolutionary factors affect patterns of host shifts and disease emergence.
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Affiliation(s)
- Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
- * E-mail:
| | | | - Colin A. Russell
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - John J. Welch
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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Abstract
MOTIVATION Genetic variation in cis-regulatory elements is an important cause of variation in gene expression. Cis-regulatory variation can be detected by using high-throughput RNA sequencing (RNA-seq) to identify differences in the expression of the two alleles of a gene. This requires that reads from the two alleles are equally likely to map to a reference genome(s), and that single-nucleotide polymorphisms (SNPs) are accurately called, so that reads derived from the different alleles can be identified. Both of these prerequisites can be achieved by sequencing the genomes of the parents of the individual being studied, but this is often prohibitively costly. RESULTS In Drosophila, we demonstrate that biases during read mapping can be avoided by mapping reads to two alternative genomes that incorporate SNPs called from the RNA-seq data. The SNPs can be reliably called from the RNA-seq data itself, provided any variants not found in high-quality SNP databases are filtered out. Finally, we suggest a way of measuring allele-specific expression (ASE) by crossing the line of interest to a reference line with a high-quality genome sequence. Combined with our bioinformatic methods, this approach minimizes mapping biases, allows poor-quality data to be identified and removed and aides in the biological interpretation of the data as the parent of origin of each allele is known. In conclusion, our results suggest that accurate estimates of ASE do not require the parental genomes of the individual being studied to be sequenced. AVAILABILITY AND IMPLEMENTATION Scripts used to perform our analysis are available at https://github.com/d-quinn/bio_quinn2013.
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Affiliation(s)
- Andrew Quinn
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, UK
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45
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Wilfert L, Jiggins FM. Flies on the move: an inherited virus mirrors Drosophila melanogaster's elusive ecology and demography. Mol Ecol 2014; 23:2093-104. [PMID: 24597631 DOI: 10.1111/mec.12709] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/15/2013] [Revised: 02/27/2014] [Accepted: 02/28/2014] [Indexed: 11/30/2022]
Abstract
Vertically transmitted parasites rely on their host's reproduction for their transmission, leading to the evolutionary histories of both parties being intimately entwined. Parasites can thus serve as a population genetic magnifying glass for their host's demographic history. Here, we study the fruitfly Drosophila melanogaster's vertically transmitted sigma virus DMelSV. The virus has a high mutation rate and low effective population size, allowing us to reconstruct at a fine scale how the combined forces of the movement of flies and selection on the virus have shaped its migration patterns. We found that the virus is likely to have spread to Europe from Africa, mirroring the colonization route of Drosophila. The North American DMelSV population appears to be the result of a recent single immigration from Europe, invading together with its host in the late 19th century. Across Europe, DMelSV migration rates are low and populations are highly genetically structured, likely reflecting limited fly movement. Despite being intolerant of extreme cold, viral diversity suggests that fly populations can persist in harsh continental climates and that recolonization from the warmer south plays a minor role. In conclusion, studying DMelSV can provide insights into the poorly understood ecology of D. melanogaster, one of the best-studied organisms in biology.
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Affiliation(s)
- Lena Wilfert
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, TR10 9FE, UK
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46
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Chrostek E, Marialva MSP, Esteves SS, Weinert LA, Martinez J, Jiggins FM, Teixeira L. Wolbachia variants induce differential protection to viruses in Drosophila melanogaster: a phenotypic and phylogenomic analysis. PLoS Genet 2013; 9:e1003896. [PMID: 24348259 PMCID: PMC3861217 DOI: 10.1371/journal.pgen.1003896] [Citation(s) in RCA: 201] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 09/06/2013] [Indexed: 12/22/2022] Open
Abstract
Wolbachia are intracellular bacterial symbionts that are able to protect various insect hosts from viral infections. This tripartite interaction was initially described in Drosophila melanogaster carrying wMel, its natural Wolbachia strain. wMel has been shown to be genetically polymorphic and there has been a recent change in variant frequencies in natural populations. We have compared the antiviral protection conferred by different wMel variants, their titres and influence on host longevity, in a genetically identical D. melanogaster host. The phenotypes cluster the variants into two groups--wMelCS-like and wMel-like. wMelCS-like variants give stronger protection against Drosophila C virus and Flock House virus, reach higher titres and often shorten the host lifespan. We have sequenced and assembled the genomes of these Wolbachia, and shown that the two phenotypic groups are two monophyletic groups. We have also analysed a virulent and over-replicating variant, wMelPop, which protects D. melanogaster even better than the closely related wMelCS. We have found that a ~21 kb region of the genome, encoding eight genes, is amplified seven times in wMelPop and may be the cause of its phenotypes. Our results indicate that the more protective wMelCS-like variants, which sometimes have a cost, were replaced by the less protective but more benign wMel-like variants. This has resulted in a recent reduction in virus resistance in D. melanogaster in natural populations worldwide. Our work helps to understand the natural variation in wMel and its evolutionary dynamics, and inform the use of Wolbachia in arthropod-borne disease control.
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Affiliation(s)
- Ewa Chrostek
- Instituto Gulbenkian de Ciência, Oeiras, Portugal
| | | | | | - Lucy A. Weinert
- Department of Veterinary Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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47
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Longdon B, Cao C, Martinez J, Jiggins FM. Previous exposure to an RNA virus does not protect against subsequent infection in Drosophila melanogaster. PLoS One 2013; 8:e73833. [PMID: 24040086 PMCID: PMC3770682 DOI: 10.1371/journal.pone.0073833] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2013] [Accepted: 07/31/2013] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND Immune priming has been shown to occur in a wide array of invertebrate taxa, with individuals exposed to a pathogen showing increased protection upon subsequent exposure. However, the mechanisms underlying immune priming are poorly understood. The antiviral RNAi response in Drosophila melanogaster is an ideal candidate for providing a specific and acquired response to subsequent infection. We exposed D. melanogaster to two challenges of a virus known to produce an antiviral RNAi response, to examine whether any protective effects of prior exposure on survival were observed. RESULTS In this experiment we found no evidence that prior exposure to Drosophila C Virus (DCV) protects flies from a subsequent lethal challenge, with almost identical levels of mortality in flies previously exposed to DCV or a control. CONCLUSIONS Our results confirm the finding that 'acquired' immune responses are not ubiquitous across all invertebrate-pathogen interactions. We discuss why we may have observed no effect in this study, with focus on the mechanistic basis of the RNAi pathway.
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Affiliation(s)
- Ben Longdon
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Chuan Cao
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Julien Martinez
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
| | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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48
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Abstract
Wolbachia bacteria are common endosymbionts of insects, and some strains are known to protect their hosts against RNA viruses and other parasites. This has led to the suggestion that releasing Wolbachia-infected mosquitoes could prevent the transmission of arboviruses and other human parasites. We have identified Wolbachia in Kenyan populations of the yellow fever vector Aedes bromeliae and its relative Aedes metallicus, and in Mansonia uniformis and Mansonia africana, which are vectors of lymphatic filariasis. These Wolbachia strains cluster together on the bacterial phylogeny, and belong to bacterial clades that have recombined with other unrelated strains. These new Wolbachia strains may be affecting disease transmission rates of infected mosquito species, and could be transferred into other mosquito vectors as part of control programs.
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Affiliation(s)
- Jewelna Osei-Poku
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom.
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49
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Abstract
Host-parasite coevolution can result in consecutive selective sweeps of host resistance alleles and parasite counter-adaptations. To illustrate the dynamics of this important but little studied form of coevolution, we have modeled an ongoing arms race between Drosophila melanogaster and the vertically transmitted sigma virus, using parameters we estimated in the field. We integrate these results with previous work showing that the spread of a resistance allele of the ref(2)P gene in the host was followed by the spread of a virus genotype, which overcomes this resistance. In line with these observations, our model predicts that there can be rapid selective sweeps in both the host and parasite, which can drive large changes in the prevalence of infection. The virus will tend to be ahead in the arms race, as incomplete dominance slows down host adaptation and selection for host resistance is weaker than selection for parasites to overcome resistance--the "life-dinner" principle. This asymmetry in the adaptation rates results in a partial sweep of the host resistance allele, as it loses its advantage part way through the selective sweep. This well-understood natural system illustrates how the outcome of host-parasite coevolution is determined by different population genetic parameters in the field.
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Affiliation(s)
- Lena Wilfert
- Department of Genetics, University of Cambridge, Cambridge CB2 3EH, United Kingdom.
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50
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Magwire MM, Fabian DK, Schweyen H, Cao C, Longdon B, Bayer F, Jiggins FM. Genome-wide association studies reveal a simple genetic basis of resistance to naturally coevolving viruses in Drosophila melanogaster. PLoS Genet 2012; 8:e1003057. [PMID: 23166512 PMCID: PMC3499358 DOI: 10.1371/journal.pgen.1003057] [Citation(s) in RCA: 107] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2012] [Accepted: 09/14/2012] [Indexed: 12/04/2022] Open
Abstract
Variation in susceptibility to infectious disease often has a substantial genetic component in animal and plant populations. We have used genome-wide association studies (GWAS) in Drosophila melanogaster to identify the genetic basis of variation in susceptibility to viral infection. We found that there is substantially more genetic variation in susceptibility to two viruses that naturally infect D. melanogaster (DCV and DMelSV) than to two viruses isolated from other insects (FHV and DAffSV). Furthermore, this increased variation is caused by a small number of common polymorphisms that have a major effect on resistance and can individually explain up to 47% of the heritability in disease susceptibility. For two of these polymorphisms, it has previously been shown that they have been driven to a high frequency by natural selection. An advantage of GWAS in Drosophila is that the results can be confirmed experimentally. We verified that a gene called pastrel--which was previously not known to have an antiviral function--is associated with DCV-resistance by knocking down its expression by RNAi. Our data suggest that selection for resistance to infectious disease can increase genetic variation by increasing the frequency of major-effect alleles, and this has resulted in a simple genetic basis to variation in virus resistance.
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Affiliation(s)
| | | | | | | | | | | | - Francis M. Jiggins
- Department of Genetics, University of Cambridge, Cambridge, United Kingdom
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