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Hedtke SM, Post RJ, Feleke SM, Gebretsadik FS, Boakye DA, Krueger A, Grant WN, Wilding CS. Cytotaxonomic characterization and estimation of migration patterns of onchocerciasis vectors (Simulium damnosum sensu lato) in northwestern Ethiopia based on RADSeq data. PLoS Negl Trop Dis 2024; 18:e0011868. [PMID: 38175836 DOI: 10.1371/journal.pntd.0011868] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2023] [Revised: 01/17/2024] [Accepted: 12/17/2023] [Indexed: 01/06/2024] Open
Abstract
BACKGROUND While much progress has been made in the control and elimination of onchocerciasis across Africa, the extent to which vector migration might confound progress towards elimination or result in re-establishment of endemism in areas where transmission has been eliminated remains unclear. In Northern Ethiopia, Metema and Metekel-two foci located near the Sudan border-exhibit continuing transmission. While progress towards elimination has been faster in Metema, there remains a problematic hotspot of transmission. Whether migration from Metekel contributes to this is currently unknown. METHODOLOGY/PRINCIPLE FINDINGS To assess the role of vector migration from Metekel into Metema, we present a population genomics study of 151 adult female vectors using 47,638 RADseq markers and mtDNA CoI sequencing. From additional cytotaxonomy data we identified a new cytoform in Metema, closely related to S. damnosum s.str, here called the Gondar form. RADseq data strongly indicate the existence of two distinctly differentiated clusters within S. damnosum s.l.: one genotypic cluster found only in Metema, and the second found predominantly in Metekel. Because blackflies from both clusters were found in sympatry (in all four collection sites in Metema), but hybrid genotypes were not detected, there may be reproductive barriers preventing interbreeding. The dominant genotype in Metema was not found in Metekel while the dominant genotype in Metekel was found in Metema, indicating that (at the time of sampling) migration is primarily unidirectional, with flies moving from Metekel to Metema. There was strong differentiation between clusters but little genetic differentiation within clusters, suggesting migration and gene flow of flies within the same genetic cluster are sufficient to prevent genetic divergence between sites. CONCLUSIONS/SIGNIFICANCE Our results confirm that Metekel and Metema represent different transmission foci, but also indicate a northward movement of vectors between foci that may have epidemiological importance, although its significance requires further study.
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Affiliation(s)
- Shannon M Hedtke
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Rory J Post
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
- Disease Control Department, London School of Hygiene and Tropical Medicine, London, United Kingdom
| | | | - Fikre Seife Gebretsadik
- Neglected Tropical Disease Prevention and Control Program, Federal Ministry of Health, Addis Ababa, Ethiopia
| | - Daniel A Boakye
- Parasitology Department, Noguchi Memorial Institute for Medical Research, Accra, Ghana
| | - Andreas Krueger
- Military Hospital Hamburg, Department Tropical Medicine, Hamburg, Germany
| | - Warwick N Grant
- Department of Environment and Genetics, School of Agriculture, Biomedicine and Environment, La Trobe University, Bundoora, Victoria, Australia
| | - Craig S Wilding
- School of Biological and Environmental Sciences, Liverpool John Moores University, Liverpool, United Kingdom
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Pescod P, Bevivino G, Anthousi A, Shelton R, Shepherd J, Lombardo F, Nolan T. Measuring the Impact of Genetic Heterogeneity and Chromosomal Inversions on the Efficacy of CRISPR-Cas9 Gene Drives in Different Strains of Anopheles gambiae. CRISPR J 2023; 6:419-429. [PMID: 37702604 DOI: 10.1089/crispr.2023.0029] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/14/2023] Open
Abstract
The human malaria vector Anopheles gambiae is becoming increasingly resistant to insecticides, spurring the development of genetic control strategies. CRISPR-Cas9 gene drives can modify a population by creating double-stranded breaks at highly specific targets, triggering copying of the gene drive into the cut site ("homing"), ensuring its inheritance. The DNA repair mechanism responsible requires homology between the donor and recipient chromosomes, presenting challenges for the invasion of laboratory-developed gene drives into wild populations of target species An. gambiae species complex, which show high levels of genome variation. Two gene drives (vas2-5958 and zpg-7280) were introduced into three An. gambiae strains collected across Africa with 5.3-6.6% variation around the target sites, and the effect of this variation on homing was measured. Gene drive homing across different karyotypes of the 2La chromosomal inversion was also assessed. No decrease in gene drive homing was seen despite target site heterology, demonstrating the applicability of gene drives to wild populations.
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Affiliation(s)
- Poppy Pescod
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Giulia Bevivino
- Division of Parasitology, Department of Public Health and Infectious Diseases, University of Rome "la Sapienza," Rome, Italy; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Amalia Anthousi
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Biology, University of Crete, Heraklion, Crete, Greece; and Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
- Department of Insects and Vector Borne Diseases, Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Ruth Shelton
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Josephine Shepherd
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Fabrizio Lombardo
- Division of Parasitology, Department of Public Health and Infectious Diseases, University of Rome "la Sapienza," Rome, Italy; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
| | - Tony Nolan
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, United Kingdom; Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology-Hellas, Heraklion, Greece
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Odero JO, Nambunga IH, Wangrawa DW, Badolo A, Weetman D, Koekemoer LL, Ferguson HM, Okumu FO, Baldini F. Advances in the genetic characterization of the malaria vector, Anopheles funestus, and implications for improved surveillance and control. Malar J 2023; 22:230. [PMID: 37553665 PMCID: PMC10410966 DOI: 10.1186/s12936-023-04662-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Accepted: 07/28/2023] [Indexed: 08/10/2023] Open
Abstract
Anopheles mosquitoes present a major public health challenge in sub-Saharan Africa; notably, as vectors of malaria that kill over half a million people annually. In parts of the east and southern Africa region, one species in the Funestus group, Anopheles funestus, has established itself as an exceptionally dominant vector in some areas, it is responsible for more than 90% of all malaria transmission events. However, compared to other malaria vectors, the species is far less studied, partly due to difficulties in laboratory colonization and the unresolved aspects of its taxonomy and systematics. Control of An. funestus is also increasingly difficult because it has developed widespread resistance to public health insecticides. Fortunately, recent advances in molecular techniques are enabling greater insights into species identity, gene flow patterns, population structure, and the spread of resistance in mosquitoes. These advances and their potential applications are reviewed with a focus on four research themes relevant to the biology and control of An. funestus in Africa, namely: (i) the taxonomic characterization of different vector species within the Funestus group and their role in malaria transmission; (ii) insecticide resistance profile; (iii) population genetic diversity and gene flow, and (iv) applications of genetic technologies for surveillance and control. The research gaps and opportunities identified in this review will provide a basis for improving the surveillance and control of An. funestus and malaria transmission in Africa.
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Affiliation(s)
- Joel O Odero
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania.
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
| | - Ismail H Nambunga
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
| | - Dimitri W Wangrawa
- Laboratoire d'Entomologie Fondamentale et Appliquée, Université Joseph ZEBRO, Ouagadougou, Burkina Faso
| | - Athanase Badolo
- Laboratoire d'Entomologie Fondamentale et Appliquée, Université Joseph ZEBRO, Ouagadougou, Burkina Faso
| | - David Weetman
- Department of Vector Biology, Liverpool School of Tropical Medicine, Liverpool, L3 5QA, UK
| | - Lizette L Koekemoer
- Wits Research Institute for Malaria, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Centre for Emerging Zoonotic Parasitic Diseases, Vector Control Reference Laboratory, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
| | - Heather M Ferguson
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
| | - Fredros O Okumu
- Environmental Health and Ecological Sciences Department, Ifakara Health Institute, Ifakara, Tanzania
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK
- School of Public Health, Faculty of Health Science, University of the Witwatersrand, Johannesburg, South Africa
- School of Life Science and Biotechnology, Nelson Mandela African Institution of Science and Technology, Arusha, Tanzania
| | - Francesco Baldini
- School of Biodiversity, One Health, and Veterinary Medicine, University of Glasgow, Glasgow, G12 8QQ, UK.
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Cohen ZP, Schoville SD, Hawthorne DJ. The role of structural variants in pest adaptation and genome evolution of the Colorado potato beetle, Leptinotarsa decemlineata (Say). Mol Ecol 2023; 32:1425-1440. [PMID: 36591939 DOI: 10.1111/mec.16838] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2021] [Revised: 11/30/2022] [Accepted: 12/15/2022] [Indexed: 01/03/2023]
Abstract
Structural variation has been associated with genetic diversity and adaptation. Despite these observations, it is not clear what their relative importance is for evolution, especially in rapidly adapting species. Here, we examine the significance of structural polymorphisms in pesticide resistance evolution of the agricultural super-pest, the Colorado potato beetle, Leptinotarsa decemlineata. By employing a parent offspring trio sequencing procedure, we develop highly contiguous reference genomes to characterize structural variation. These updated assemblies represent >100-fold improvement of contiguity and include derived pest and ancestral nonpest individuals. We identify >200,000 structural variations, which appear to be nonrandomly distributed across the genome as they co-occur with transposable elements and genes. Structural variations intersect with exons in a large proportion of gene annotations (~20%) that are associated with insecticide resistance (including cytochrome P450s), development, and transcription. To understand the role structural variations play in adaptation, we measure their allele frequencies among an additional 57 individuals using whole genome resequencing data, which represents pest and nonpest populations of North America. Incorporating multiple independent tests to detect the signature of natural selection using SNP data, we identify 14 genes that are probably under positive selection, include structural variations, and SNPs of elevated frequency within the pest lineages. Among these, three are associated with insecticide resistance based on previous research. One of these genes, CYP4g15, is coinduced during insecticide exposure with glycosyltransferase-13, which is a duplicated gene enclosed within a structural variant adjacent to the CYP4g15 genic region. These results demonstrate the significance of structural variations as a genomic feature to describe species history, genetic diversity, and adaptation.
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Affiliation(s)
- Zachary P Cohen
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
| | - Sean D Schoville
- Department of Entomology, University of Wisconsin-Madison, Madison, Wisconsin, USA
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Pollegioni P, Persampieri T, Minuz RL, Bucci A, Trusso A, Martino SD, Leo C, Bruttini M, Ciolfi M, Waldvogel A, Tripet F, Simoni A, Crisanti A, Müller R. Introgression of a synthetic sex ratio distortion transgene into different genetic backgrounds of Anopheles coluzzii. INSECT MOLECULAR BIOLOGY 2023; 32:56-68. [PMID: 36251429 PMCID: PMC10092091 DOI: 10.1111/imb.12813] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 06/26/2022] [Accepted: 10/10/2022] [Indexed: 06/16/2023]
Abstract
The development of genetically modified mosquitoes (GMM) and their subsequent field release offers innovative approaches for vector control of malaria. A non-gene drive self-limiting male-bias Ag(PMB)1 strain has been developed in a 47-year-old laboratory G3 strain of Anopheles gambiae s.l. When Ag(PMB)1 males are crossed to wild-type females, expression of the endonuclease I-PpoI during spermatogenesis causes the meiotic cleavage of the X chromosome in sperm cells, leading to fertile offspring with a 95% male bias. However, World Health Organization states that the functionality of the transgene could differ when inserted in different genetic backgrounds of Anopheles coluzzii which is currently a predominant species in several West-African countries and thus a likely recipient for a potential release of self-limiting GMMs. In this study, we introgressed the transgene from the donor Ag(PMB)1 by six serial backcrosses into two recipient colonies of An. coluzzii that had been isolated in Mali and Burkina Faso. Scans of informative Single Nucleotide Polymorphism (SNP) markers and whole-genome sequencing analysis revealed a nearly complete introgression of chromosomes 3 and X, but a remarkable genomic divergence in a large region of chromosome 2 between the later backcrossed (BC6) transgenic offspring and the recipient paternal strains. These findings suggested to extend the backcrossing breeding strategy beyond BC6 generation and increasing the introgression efficiency of critical regions that have ecological and epidemiological implications through the targeted selection of specific markers. Disregarding differential introgression efficiency, we concluded that the phenotype of the sex ratio distorter is stable in the BC6 introgressed An. coluzzii strains.
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Affiliation(s)
- Paola Pollegioni
- Research Institute on Terrestrial EcosystemsNational Research CouncilTerniItaly
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Tania Persampieri
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Roxana L. Minuz
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Alessandro Bucci
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Alessandro Trusso
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Salvatore Di Martino
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Chiara Leo
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Marco Bruttini
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
- Tuscan Centre of Precision Medicine, Department of Medicine, Surgery and NeurosciencesUniversity of SienaSienaItaly
| | - Marco Ciolfi
- Research Institute on Terrestrial EcosystemsNational Research CouncilTerniItaly
| | | | - Frédéric Tripet
- Centre for Applied Entomology and ParasitologyKeele UniversityNewcastle‐under‐LymeUK
| | - Alekos Simoni
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
| | - Andrea Crisanti
- Department of Molecular MedicineUniversity of PadovaPadovaItaly
| | - Ruth Müller
- Genetics and Ecology Research CentrePolo d'Innovazione di Genomica, Genetica e BiologiaTerniItaly
- Unit Entomology, Department of Biomedical SciencesInstitute of Tropical MedicineAntwerpBelgium
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Mwagira-Maina S, Runo S, Wachira L, Kitur S, Nyasende S, Kemei B, Ochomo E, Matoke-Muhia D, Mbogo C, Kamau L. Genetic markers associated with insecticide resistance and resting behaviour in Anopheles gambiae mosquitoes in selected sites in Kenya. Malar J 2021; 20:461. [PMID: 34903240 PMCID: PMC8670025 DOI: 10.1186/s12936-021-03997-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2021] [Accepted: 11/28/2021] [Indexed: 11/16/2022] Open
Abstract
Background Molecular diagnostic tools have been incorporated in insecticide resistance monitoring programmes to identify underlying genetic basis of resistance and develop early warning systems of vector control failure. Identifying genetic markers of insecticide resistance is crucial in enhancing the ability to mitigate potential effects of resistance. The knockdown resistance (kdr) mutation associated with resistance to DDT and pyrethroids, the acetylcholinesterase-1 (ace-1R) mutation associated with resistance to organophosphates and carbamates and 2La chromosomal inversion associated with indoor resting behaviour, were investigated in the present study. Methods Anopheles mosquitoes sampled from different sites in Kenya and collected within the context of malaria vector surveillance were analysed. Mosquitoes were collected indoors using light traps, pyrethrum spray and hand catches between August 2016 and November 2017. Mosquitoes were identified using morphological keys and Anopheles gambiae sensu lato (s.l.) mosquitoes further identified into sibling species by the polymerase chain reaction method following DNA extraction by alcohol precipitation. Anopheles gambiae and Anopheles arabiensis were analysed for the presence of the kdr and ace-1R mutations, while 2La inversion was only screened for in An. gambiae where it is polymorphic. Chi-square statistics were used to determine correlation between the 2La inversion karyotype and kdr-east mutation. Results The kdr-east mutation occurred at frequencies ranging from 0.5 to 65.6% between sites. The kdr-west mutation was only found in Migori at a total frequency of 5.3% (n = 124). No kdr mutants were detected in Tana River. The ace-1R mutation was absent in all populations. The 2La chromosomal inversion screened in An. gambiae occurred at frequencies of 87% (n = 30), 80% (n = 10) and 52% (n = 50) in Baringo, Tana River and Migori, respectively. A significant association between the 2La chromosomal inversion and the kdr-east mutation was found. Conclusion The significant association between the 2La inversion karyotype and kdr-east mutation suggests that pyrethroid resistant An. gambiae continue to rest indoors regardless of the presence of treated bed nets and residual sprays, a persistence further substantiated by studies documenting continued mosquito abundance indoors. Behavioural resistance by which Anopheles vectors prefer not to rest indoors may, therefore, not be a factor of concern in this study’s malaria vector populations.
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Affiliation(s)
- Sharon Mwagira-Maina
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya.
| | - Steven Runo
- Department of Biochemistry and Biotechnology, Kenyatta University, P.O Box 43844-00100, Nairobi, Kenya
| | - Lucy Wachira
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Stanley Kitur
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Sarah Nyasende
- Institute of Tropical Medicine and Infectious Diseases (ITROMID), P.O. Box 54840-00200, Nairobi, Kenya
| | - Brigid Kemei
- Centre for Global Health Research, KEMRI_CDC, P.O Box 1578-40100, Kisumu, Kenya
| | - Eric Ochomo
- Centre for Global Health Research, KEMRI_CDC, P.O Box 1578-40100, Kisumu, Kenya
| | - Damaris Matoke-Muhia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
| | - Charles Mbogo
- KEMRI -Wellcome Trust Research Programme, Public Health Unit, P.O. Box 43640-00100, Nairobi, Kenya
| | - Luna Kamau
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute (KEMRI), P.O Box 54840-00200, Nairobi, Kenya
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Adeogun A, Popoola K, Brooke B, Olakiigbe A, Awolola S. Polymorphic inversion 2La frequencies associated with ecotypes in populations of Anopheles coluzzii from Southwest Nigeria. SCIENTIFIC AFRICAN 2021. [DOI: 10.1016/j.sciaf.2021.e00746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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2La Paracentric Chromosomal Inversion and Overexpressed Metabolic Genes Enhance Thermotolerance and Pyrethroid Resistance in the Major Malaria Vector Anopheles gambiae. BIOLOGY 2021; 10:biology10060518. [PMID: 34200806 PMCID: PMC8230517 DOI: 10.3390/biology10060518] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 06/05/2021] [Accepted: 06/07/2021] [Indexed: 01/31/2023]
Abstract
Changes in global temperature are impacting the spread/intensity of vector-borne diseases, including malaria, and accelerating evolutionary/adaptive changes in vector species. These changes, including chromosomal inversions and overexpression and/or changes in allele frequencies of thermotolerance-associated genes, may facilitate insecticide resistance through pleiotropy. This study investigated the impact of thermotolerance on pyrethroid resistance in four populations of the malaria vector An. gambiae s.l., from the savanna/sub-Sahel of northern Nigeria. Anopheles coluzzii and An. gambiae s.s. were the only malaria vectors found, sympatric in all the sites, with the former species predominant. High thermotolerance was observed, with no mortality at 38 °C, and LT50 of ~44 °C. Significantly high permethrin resistance was observed (mortality < 50%) in 44 °C heat-hardened (exposure to an intermediately high temperature provides protection to a more severe temperature or insecticide) larvae from two sites, BUK and Pantami, compared with the control, and heat-hardened adult females from Auyo (mortality = 3.00% ± 1.20, χ2 = 5.83, p < 0.01) compared with the control (12.00% ± 4.65). The 2La chromosomal inversion was detected at ~50% in subset of larvae and 58% in subset of adult females genotyped. A significant association was observed (OR = 7.2, p < 0.03) between permethrin resistance and the 2La/+a rearrangement compared with 2L+a/+a, in BUK larvae. For all sites, permethrin resistance correlated with 2La/a homozygosity in adult females (R = 5.02, p = 0.01). qRT-PCR identified six genes commonly induced/overexpressed, including the heat shock protein 70 (AGAP004581) which was 2468× and 5× overexpressed in heat-hardened and permethrin-resistant females, respectively; trehalose-6-phosphate synthase (AGAP008227); and the ionotropic glutamate receptor genes, IR25a (AGAP010272) and IR21a (AGAP008511). This study highlights challenges associated with insecticide-based malaria vector control, and the epidemiological significance of taking climate variables into account for the design/choice of control measures.
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Holmes CJ, Benoit JB. Biological Adaptations Associated with Dehydration in Mosquitoes. INSECTS 2019; 10:insects10110375. [PMID: 31661928 PMCID: PMC6920799 DOI: 10.3390/insects10110375] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/22/2019] [Accepted: 10/23/2019] [Indexed: 12/05/2022]
Abstract
Diseases that are transmitted by mosquitoes are a tremendous health and socioeconomic burden with hundreds of millions of people being impacted by mosquito-borne illnesses annually. Many factors have been implicated and extensively studied in disease transmission dynamics, but knowledge regarding how dehydration impacts mosquito physiology, behavior, and resulting mosquito-borne disease transmission remain underdeveloped. The lapse in understanding on how mosquitoes respond to dehydration stress likely obscures our ability to effectively study mosquito physiology, behavior, and vectorial capabilities. The goal of this review is to develop a profile of factors underlying mosquito biology that are altered by dehydration and the implications that are related to disease transmission.
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Affiliation(s)
- Christopher J Holmes
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
| | - Joshua B Benoit
- Department of Biological Sciences, University of Cincinnati, Cincinnati, OH 45221, USA.
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Mashatola T, Ndo C, Koekemoer LL, Dandalo LC, Wood OR, Malakoane L, Poumachu Y, Lobb LN, Kaiser M, Bourtzis K, Munhenga G. A review on the progress of sex-separation techniques for sterile insect technique applications against Anopheles arabiensis. Parasit Vectors 2018; 11:646. [PMID: 30583746 PMCID: PMC6304763 DOI: 10.1186/s13071-018-3219-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The feasibility of the sterile insect technique (SIT) as a malaria vector control strategy against Anopheles arabiensis has been under investigation over the past decade. One of the critical steps required for the application of this technique to mosquito control is the availability of an efficient and effective sex-separation system. Sex-separation systems eliminate female mosquitoes from the production line prior to irradiation and field release of sterile males. This is necessary because female mosquitoes can transmit pathogens such as malaria and, therefore, their release must be prevented. Sex separation also increases the efficiency of an SIT programme. Various sex-separation strategies have been explored including the exploitation of developmental and behavioural differences between male and female mosquitoes, and genetic approaches. Most of these are however species-specific and are not indicated for the major African malaria vectors such as An. arabiensis. As there is currently no reliable sex-separation method for An. arabiensis, various strategies were explored in an attempt to develop a robust system that can be applied on a mass-rearing scale. The progress and challenges faced during the development of a sexing system for future pilot and/or large-scale SIT release programmes against An. arabiensis are reviewed here. Three methods of sex separation were examined. The first is the use of pupal size for gender prediction. The second is the elimination of blood-feeding adult females through the addition of an endectocide to a blood meal source. The third is the establishment of a genetic sexing strain (GSS) carrying an insecticide resistance selectable marker (dieldrin-resistance rdl gene and/or other GABA receptor antagonists that can be used as alternative insecticides to dieldrin) or a temperature-sensitive lethal marker.
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Affiliation(s)
- Thabo Mashatola
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Cyrille Ndo
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Institut de recherche de Yaoundé (IRY), Yaoundé, Cameroon
- Department of Biological Sciences, Faculty of Medicine and Pharmaceutical Sciences, University of Douala, Douala, Cameroon
- Centre for Research in Infectious Disease (CRI), Yaoundé, Cameroon
| | - Lizette L. Koekemoer
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Leonard C. Dandalo
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Oliver R. Wood
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Lerato Malakoane
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Yacouba Poumachu
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
- Organisation de Coordination pour la lutte Contre les Endémies en Afrique Centrale (OCEAC), Institut de recherche de Yaoundé (IRY), Yaoundé, Cameroon
- Vector Borne Disease Laboratory of the Applied Biology and Ecology Research Unit (VBDL-URBEA) Department of Animal Biology, Faculty of Sciences of the University of Dschang, Dschang, Cameroon
| | - Leanne N. Lobb
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Maria Kaiser
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
| | - Kostas Bourtzis
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Givemore Munhenga
- Centre for Emerging Zoonotic and Parasitic Diseases, National Institute for Communicable Diseases of the National Health Laboratory Service, Johannesburg, South Africa
- Wits Research Institute for Malaria, MRC Collaborating Centre for Multi-Disciplinary Research on Malaria, School of Pathology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa
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11
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Riehle MM, Bukhari T, Gneme A, Guelbeogo WM, Coulibaly B, Fofana A, Pain A, Bischoff E, Renaud F, Beavogui AH, Traore SF, Sagnon N, Vernick KD. The Anopheles gambiae 2La chromosome inversion is associated with susceptibility to Plasmodium falciparum in Africa. eLife 2017. [PMID: 28643631 PMCID: PMC5482571 DOI: 10.7554/elife.25813] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Chromosome inversions suppress genetic recombination and establish co-adapted gene complexes, or supergenes. The 2La inversion is a widespread polymorphism in the Anopheles gambiae species complex, the major African mosquito vectors of human malaria. Here we show that alleles of the 2La inversion are associated with natural malaria infection levels in wild-captured vectors from West and East Africa. Mosquitoes carrying the more-susceptible allele (2L+a) are also behaviorally less likely to be found inside houses. Vector control tools that target indoor-resting mosquitoes, such as bednets and insecticides, are currently the cornerstone of malaria control in Africa. Populations with high levels of the 2L+a allele may form reservoirs of persistent outdoor malaria transmission requiring novel measures for surveillance and control. The 2La inversion is a major and previously unappreciated component of the natural malaria transmission system in Africa, influencing both malaria susceptibility and vector behavior.
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Affiliation(s)
- Michelle M Riehle
- Department of Microbiology and Immunology, University of Minnesota, Minneapolis, United States
| | - Tullu Bukhari
- Department of Zoology, Maseno University, Maseno, Kenya
| | - Awa Gneme
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Wamdaogo M Guelbeogo
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Boubacar Coulibaly
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - Abdrahamane Fofana
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - Adrien Pain
- Department of Parasites and Insect Vectors, Unit of Genetics and Genomics of Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Hosts, Vectors and Pathogens, Paris, France.,Bioinformatics and Biostatistics Hub (C3BI), USR 3756 IP CNRS, Institut Pasteur, Paris, France
| | - Emmanuel Bischoff
- Department of Parasites and Insect Vectors, Unit of Genetics and Genomics of Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Hosts, Vectors and Pathogens, Paris, France
| | - Francois Renaud
- Laboratoire Maladies Infectieuses et Vecteurs: Ecologie Génétique, Evolution et Contrôle (MIVEGEC), Institut de Recherche pour le Développement (IRD), Montpellier, France.,UMR 224-5290, Centre National de la Recherche Scientifique (CNRS), Montpellier, France
| | - Abdoul H Beavogui
- Centre de Formation et de Recherche en Santé Rurale de Mafèrinyah, Conakry, Guinea
| | - Sekou F Traore
- Malaria Research and Training Centre, Faculty of Medicine and Dentistry, University of Mali, Bamako, Mali
| | - N'Fale Sagnon
- Centre National de Recherche et de Formation sur le Paludisme, Ouagadougou, Burkina Faso
| | - Kenneth D Vernick
- Department of Parasites and Insect Vectors, Unit of Genetics and Genomics of Insect Vectors, Institut Pasteur, Paris, France.,CNRS Unit of Hosts, Vectors and Pathogens, Paris, France
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12
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Ayala D, Acevedo P, Pombi M, Dia I, Boccolini D, Costantini C, Simard F, Fontenille D. Chromosome inversions and ecological plasticity in the main African malaria mosquitoes. Evolution 2017; 71:686-701. [PMID: 28071788 DOI: 10.1111/evo.13176] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2016] [Accepted: 12/22/2016] [Indexed: 01/30/2023]
Abstract
Chromosome inversions have fascinated the scientific community, mainly because of their role in the rapid adaption of different taxa to changing environments. However, the ecological traits linked to chromosome inversions have been poorly studied. Here, we investigated the roles played by 23 chromosome inversions in the adaptation of the four major African malaria mosquitoes to local environments in Africa. We studied their distribution patterns by using spatially explicit modeling and characterized the ecogeographical determinants of each inversion range. We then performed hierarchical clustering and constrained ordination analyses to assess the spatial and ecological similarities among inversions. Our results show that most inversions are environmentally structured, suggesting that they are actively involved in processes of local adaptation. Some inversions exhibited similar geographical patterns and ecological requirements among the four mosquito species, providing evidence for parallel evolution. Conversely, common inversion polymorphisms between sibling species displayed divergent ecological patterns, suggesting that they might have a different adaptive role in each species. These results are in agreement with the finding that chromosomal inversions play a role in Anopheles ecotypic adaptation. This study establishes a strong ecological basis for future genome-based analyses to elucidate the genetic mechanisms of local adaptation in these four mosquitoes.
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Affiliation(s)
- Diego Ayala
- UMR 224 MIVEGEC/ESV, IRD, Montpellier, 34394, France.,CIRMF, BP 769, Franceville, Gabon
| | - Pelayo Acevedo
- SaBio, Instituto de Investigación en Recursos Cinegéticos (IREC), CSIC-UCLM-JCCM, Ciudad Real, 13005, Spain
| | - Marco Pombi
- Sezione di Parassitologia, Dipartimento di Scienze di Sanità Pubblica, Università di Roma "La Sapienza,", Rome, 00185, Italy
| | - Ibrahima Dia
- Medical Entomology Unit, Institut Pasteur de Dakar, BP 220, Dakar, Senegal
| | - Daniela Boccolini
- Department MIPI, Unit Vector-Borne Diseases and International Health, Istituto Superiore di Sanità, Rome, 00161, Italy
| | | | | | - Didier Fontenille
- UMR 224 MIVEGEC/ESV, IRD, Montpellier, 34394, France.,Current Address: Institut Pasteur du Cambodge, BP 983, Phnom Penh, Cambodia
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13
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Matoke-Muhia D, Gimnig JE, Kamau L, Shililu J, Bayoh MN, Walker ED. Decline in frequency of the 2La chromosomal inversion in Anopheles gambiae (s.s.) in Western Kenya: correlation with increase in ownership of insecticide-treated bed nets. Parasit Vectors 2016; 9:334. [PMID: 27286834 PMCID: PMC4903000 DOI: 10.1186/s13071-016-1621-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/02/2016] [Indexed: 12/22/2022] Open
Abstract
Background The 2La chromosomal inversion, a genetic polymorphism in An. gambiae (sensu stricto) (s.s.), is associated with adaptation to microclimatic differences in humidity and desiccation resistance and mosquito behaviors. Ownership of insecticide-treated bed nets (ITNs) for malaria control has increased markedly in western Kenya in the last 20 years. An increase in the frequency of ITNs indoors could select against house entering or indoor resting of Anopheles mosquitoes. Thus, the frequency of the 2La inversion is postulated to change in An. gambiae (s.s.) with the increase of ITN ownership over time. Methods Anopheles gambiae mosquitoes were sampled between 1994 and 2011 using pyrethrum knockdown, bednet traps and human landing catches (HLC) from Asembo and Seme, western Kenya. The 2La inversion was detected by a PCR assay with primers designed for proximal breakpoints of the 2La/a and 2L+a/+a chromosomal conformation. Mosquitoes were tested for malaria parasite infection by sporozoite ELISA. Results The frequency of the 2La chromosomal inversion declined from 100 % of all chromosomes in 1994 to 17 % in 2005 and remained low through 2011 (21 %). ITN ownership increased from 0 to > 90 % of houses in the study area during this interval. The decline in the frequency of the 2La chromosomal inversion was significantly, negatively correlated with year (r = -0.93) and with increase in ITN ownership (r = -0.96). The frequency of the homo- and heterokaryotypes departed significantly from Hardy-Weinberg equilibrium, suggesting that 2La/a karyotype was under selection, earlier in its favor and later, against it. Precipitation and maximum monthly temperature did not vary over time, therefore there was no trend in climate that could account for the decline. There was no significant difference in frequency of the 2La inversion in An. gambiae (s.s.) females sampled indoors or outdoors in HCL in 2011, nor was there an association between the 2La inversion and infection with Plasmodium falciparum sporozoites. Conclusions The increase in ITN ownership in the study area was negatively correlated with the frequency of 2La inversion. The decline in 2La frequency in western Kenya is postulated to be due to differential impacts of ITNs on mosquitoes with different 2La karyotypes, possibly mediated by differences in behavior associated with the 2La karyotypes. Further research is required to determine if this is a widespread phenomenon, to further determine the association of the 2La karyotypes with mosquito behavior, and to assess whether ITNs are exerting selection mediated by differences in behavior on the different karyotypes.
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Affiliation(s)
- Damaris Matoke-Muhia
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya. .,Institute of Tropical of Medicine and Infectious diseases, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya.
| | - John E Gimnig
- Division of Parasitic Diseases and Malaria, Center for Disease Control and Prevention, Atlanta, GA, USA
| | - Luna Kamau
- Centre for Biotechnology Research and Development, Kenya Medical Research Institute, P.O. Box 54840-00200, Nairobi, Kenya
| | - Josephat Shililu
- Institute of Tropical of Medicine and Infectious diseases, Jomo Kenyatta University of Agriculture and Technology, P.O. Box 62000-00200, Nairobi, Kenya
| | - M Nabie Bayoh
- Centers for Disease Control and Prevention, PO Box 1578, Kisumu, Kenya
| | - Edward D Walker
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, 48824, USA
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14
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Islam SMA, Sajed T, Kearney CM, Baker EJ. PredSTP: a highly accurate SVM based model to predict sequential cystine stabilized peptides. BMC Bioinformatics 2015; 16:210. [PMID: 26142484 PMCID: PMC4491269 DOI: 10.1186/s12859-015-0633-x] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 06/01/2015] [Indexed: 02/07/2023] Open
Abstract
Background Numerous organisms have evolved a wide range of toxic peptides for self-defense and predation. Their effective interstitial and macro-environmental use requires energetic and structural stability. One successful group of these peptides includes a tri-disulfide domain arrangement that offers toxicity and high stability. Sequential tri-disulfide connectivity variants create highly compact disulfide folds capable of withstanding a variety of environmental stresses. Their combination of toxicity and stability make these peptides remarkably valuable for their potential as bio-insecticides, antimicrobial peptides and peptide drug candidates. However, the wide sequence variation, sources and modalities of group members impose serious limitations on our ability to rapidly identify potential members. As a result, there is a need for automated high-throughput member classification approaches that leverage their demonstrated tertiary and functional homology. Results We developed an SVM-based model to predict sequential tri-disulfide peptide (STP) toxins from peptide sequences. One optimized model, called PredSTP, predicted STPs from training set with sensitivity, specificity, precision, accuracy and a Matthews correlation coefficient of 94.86 %, 94.11 %, 84.31 %, 94.30 % and 0.86, respectively, using 200 fold cross validation. The same model outperforms existing prediction approaches in three independent out of sample testsets derived from PDB. Conclusion PredSTP can accurately identify a wide range of cystine stabilized peptide toxins directly from sequences in a species-agnostic fashion. The ability to rapidly filter sequences for potential bioactive peptides can greatly compress the time between peptide identification and testing structural and functional properties for possible antimicrobial and insecticidal candidates. A web interface is freely available to predict STP toxins from http://crick.ecs.baylor.edu/. Electronic supplementary material The online version of this article (doi:10.1186/s12859-015-0633-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
| | - Tanvir Sajed
- Department of Computer Science, University of Alberta, Edmonton, AB, Canada.
| | - Christopher Michel Kearney
- Institute of Biomedical Studies, Baylor University, Waco, TX, USA. .,Department of Biology, Baylor University, Waco, TX, USA.
| | - Erich J Baker
- Institute of Biomedical Studies, Baylor University, Waco, TX, USA. .,Department of Computer Science, Baylor University, One Bear Place #97356, Waco, TX, USA.
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15
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Ayala D, Ullastres A, González J. Adaptation through chromosomal inversions in Anopheles. Front Genet 2014; 5:129. [PMID: 24904633 PMCID: PMC4033225 DOI: 10.3389/fgene.2014.00129] [Citation(s) in RCA: 52] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2014] [Accepted: 04/22/2014] [Indexed: 12/29/2022] Open
Abstract
Chromosomal inversions have been repeatedly involved in local adaptation in a large number of animals and plants. The ecological and behavioral plasticity of Anopheles species-human malaria vectors-is mirrored by high amounts of polymorphic inversions. The adaptive significance of chromosomal inversions has been consistently attested by strong and significant correlations between their frequencies and a number of phenotypic traits. Here, we provide an extensive literature review of the different adaptive traits associated with chromosomal inversions in the genus Anopheles. Traits having important consequences for the success of present and future vector control measures, such as insecticide resistance and behavioral changes, are discussed.
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Affiliation(s)
- Diego Ayala
- UMR 224 MIVEGEC/BEES, IRD Montpellier, France ; Unité d'Entomologie Médicale, Centre International de Recherches Médicales de Franceville Franceville, Gabon
| | - Anna Ullastres
- Comparative and Computational Genomics, Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Barcelona, Spain
| | - Josefa González
- Comparative and Computational Genomics, Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra) Barcelona, Spain
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16
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Reidenbach KR, Cheng C, Liu F, Liu C, Besansky NJ, Syed Z. Cuticular differences associated with aridity acclimation in African malaria vectors carrying alternative arrangements of inversion 2La. Parasit Vectors 2014; 7:176. [PMID: 24721548 PMCID: PMC3991895 DOI: 10.1186/1756-3305-7-176] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 03/31/2014] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Principal malaria vectors in Africa, An. gambiae and An. coluzzii, share an inversion polymorphism on the left arm of chromosome 2 (2La/2L+a) that is distributed non-randomly in the environment. Genomic sequencing studies support the role of strong natural selection in maintaining steep clines in 2La inversion frequency along environmental gradients of aridity, and physiological studies have directly implicated 2La in heat and desiccation tolerance, but the precise genetic basis and the underlying behavioral and physiological mechanisms remain unknown. As the insect cuticle is the primary barrier to water loss, differences in cuticle thickness and/or epicuticular waterproofing associated with alternative 2La arrangements might help explain differences in desiccation resistance. METHODS To test that hypothesis, two subcolonies of both An. gambiae and An. coluzzii were established that were fixed for alternative 2La arrangements (2La or 2L+a) on an otherwise homosequential and shared genetic background. Adult mosquitoes reared under controlled environmental conditions (benign or arid) for eight days post-eclosion were collected and analyzed. Measurements of cuticle thickness were made based on scanning electron microscopy, and cuticular hydrocarbon (CHC) composition was evaluated by gas chromatography-mass spectrometry. RESULTS After removing the allometric effects of body weight, differences in mean cuticle thickness were found between alternative 2La karyotypes, but not between alternative environments. Moreover, the thicker cuticle of the An. coluzzii 2La karyotype was contrary to the known higher rate of water loss of this karyotype relative to 2L+a. On the other hand, quantitative differences in individual CHCs and overall CHC profiles between alternative karyotypes and environmental conditions were consistent with expectation based on previous physiological studies. CONCLUSIONS Our results suggest that alternative arrangements of the 2La inversion are associated with differences in cuticle thickness and CHC composition, but that only CHC composition appears to be relevant for desiccation resistance. Differences in the CHC composition were consistent with previous findings of a lower rate of water loss for the 2L+a karyotype at eight days post-eclosion, suggesting that CHC composition is an important strategy for maintaining water balance in this genetic background, but not for 2La. Despite a higher rate of water loss at eight days, higher body water content of the 2La karyotype confers a level of desiccation resistance equivalent to that of the 2L+a karyotype.
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Affiliation(s)
| | | | | | | | - Nora J Besansky
- Eck Institute for Global Health & Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
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17
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Moreno M, Tong C, Guzmán M, Chuquiyauri R, Llanos-Cuentas A, Rodriguez H, Gamboa D, Meister S, Winzeler EA, Maguina P, Conn JE, Vinetz JM. Infection of laboratory-colonized Anopheles darlingi mosquitoes by Plasmodium vivax. Am J Trop Med Hyg 2014; 90:612-616. [PMID: 24534811 PMCID: PMC3973502 DOI: 10.4269/ajtmh.13-0708] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
Anopheles darlingi Root is the most important malaria vector in the Amazonia region of South America. However, continuous propagation of An. darlingi in the laboratory has been elusive, limiting entomological, genetic/genomic, and vector–pathogen interaction studies of this mosquito species. Here, we report the establishment of an An. darlingi colony derived from wild-caught mosquitoes obtained in the northeastern Peruvian Amazon region of Iquitos in the Loreto Department. We show that the numbers of eggs, larvae, pupae, and adults continue to rise at least to the F6 generation. Comparison of feeding Plasmodium vivax ex vivo of F4 and F5 to F1 generation mosquitoes showed the comparable presence of oocysts and sporozoites, with numbers that corresponded to blood-stage asexual parasitemia and gametocytemia, confirming P. vivax vectorial capacity in the colonized mosquitoes. These results provide new avenues for research on An. darlingi biology and study of An. darlingi–Plasmodium interactions.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Joseph M. Vinetz
- *Address correspondence to Joseph M. Vinetz, University of California at San Diego, La Jolla, CA 92093. E-mail:
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18
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Chromosomal inversions among insecticide-resistant strains of Anopheles stephensi Liston, a malaria mosquito. Parasitol Res 2013; 112:3851-7. [PMID: 23982309 DOI: 10.1007/s00436-013-3575-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2013] [Accepted: 08/04/2013] [Indexed: 10/26/2022]
Abstract
Polytene chromosomes were prepared from the ovarian nurse cells of semi-gravid females of ten insecticide-resistant strains of Anopheles stephensi. Altogether, 16 heterozygous paracentric inversions, namely b/+ (11D-16C) in alphamethrin; i/+ (14B-18A) and h/+ (27B-28A) in DDT; j/+ (14A-16B) in chlorpyrifos; k/+ (11D-16B) in cyfluthrin; l/+ (11A-16C) in deltamethrin; m/+ (14B-15C) and e/+ (32A-33B) in bifenthrin; n/+ (12D-14B), f/+ (33A-36A) and g/+ (33C-34A) in propoxur; o/+ (11A-12D), h/+ (37A-37C) and i/+ (31C-32C) in temephos; d/+ (33D-35C) in carbofuran and a/+ (41C-43B) in neem strains, were reported. No inversions were observed in X chromosome so far. The frequency of inversions in different insecticides was found to be highest in the 2R arm, followed by the 3R arm. Such inversions were not reported in the corresponding susceptible strains or in the parental stocks.
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Abstract
Plasmodium vivax represents a special challenge to malaria control because of the ability of a single infection to relapse over months to years. P. vivax is more tolerant of low temperatures than P. falciparum, which spreads its potential range far beyond the tropics into sub-Arctic areas. Ordinary malaria control measures such as residual insecticide spraying and impregnated bed nets are effective for P. vivax, but long-lasting (up to 3 years) residual hepatic parasites (hypnozoites) mean that even well-executed malaria control programs must maintain maximal efforts for an extended period in order to eliminate indigenous infections. Hypnozoites are only eliminated by using an 8-aminoquinoline (currently only primaquine), which requires compliance with a long regimen as well as care to avoid those at risk of haemolysis due to the common genetic polymorphism, glucose-6-phosphate dehydrogenase deficiency. Risk of reintroduction of P. vivax into areas without malaria but still containing competent Anopheles vectors is enhanced as persons carrying hypnozoites are undetectable until they become symptomatic from activation of the quiescent liver parasite. Mass drug administration using drug combinations including primaquine have successfully eliminated malaria from small islands demonstrating proof of principal as a potential elimination method. It will be very difficult to maintain adequate malaria surveillance measures for years after malaria has ceased to be a public health problem, which will clearly be required to eliminate relapsing malaria such as P. vivax. New interventions will likely be required to eliminate vivax malaria; highly desirable new products include transmission-blocking vaccines, new drug combinations to treat chloroquine resistant strains and a safe, long-lasting 8-aminoquinoline.
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20
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Ayala D, Guerrero RF, Kirkpatrick M. Reproductive isolation and local adaptation quantified for a chromosome inversion in a malaria mosquito. Evolution 2012; 67:946-58. [PMID: 23550747 DOI: 10.1111/j.1558-5646.2012.01836.x] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Chromosome inversions have long been thought to be involved in speciation and local adaptation. We have little quantitative information, however, about the effects that inversion polymorphisms have on reproductive isolation and viability. Here we provide the first estimates from any organism for the total amount of reproductive isolation associated with an inversion segregating in natural populations. We sampled chromosomes from 751 mosquitoes of the malaria vector Anopheles funestus along a 1421 km transect in Cameroon that traverses savannah, highland, and rainforest ecological zones. We then developed a series of population genetic models that account for selection, migration, and assortative mating, and fit the models to the data using likelihood. Results from the best-fit models suggest there is strong local adaptation, with relative viabilities of homozygotes ranging from 25% to 130% compared to heterozygotes. Viabilities vary qualitatively between regions: the inversion is underdominant in the savannah, whereas in the highlands it is overdominant. The inversion is also implicated in strong assortative mating. In the savannah, the two homozygote forms show 92% reproductive isolation, suggesting that this one inversion can generate most of the genetic barriers needed for speciation.
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Affiliation(s)
- Diego Ayala
- Section of Integrative Biology C-0930, University of Texas, Austin, Texas 78712, USA
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21
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Koekemoer LL, Spillings BL, Christian RN, Lo TCM, Kaiser ML, Norton RA, Oliver SV, Choi KS, Brooke BD, Hunt RH, Coetzee M. Multiple Insecticide Resistance inAnopheles gambiae(Diptera: Culicidae) from Pointe Noire, Republic of the Congo. Vector Borne Zoonotic Dis 2011; 11:1193-200. [DOI: 10.1089/vbz.2010.0192] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Lizette L. Koekemoer
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Belinda L. Spillings
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Riann N. Christian
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Te-Chang M. Lo
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Maria L. Kaiser
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Ryan A.I. Norton
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Shune V. Oliver
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Kwang S. Choi
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Basil D. Brooke
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
| | - Richard H. Hunt
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- School of Animal, Plant, and Environmental Sciences, University of Witwatersrand, Johannesburg, South Africa
| | - Maureen Coetzee
- Malaria Entomology Research Unit, Faculty of Health Sciences, School of Pathology, University of the Witwatersrand, Johannesburg, South Africa
- Vector Control Reference Unit, National Institute for Communicable Diseases, National Health Laboratory Service (NHLS), Johannesburg, South Africa
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Wondji CS, Dabire RK, Tukur Z, Irving H, Djouaka R, Morgan JC. Identification and distribution of a GABA receptor mutation conferring dieldrin resistance in the malaria vector Anopheles funestus in Africa. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2011; 41:484-91. [PMID: 21501685 PMCID: PMC3579012 DOI: 10.1016/j.ibmb.2011.03.012] [Citation(s) in RCA: 97] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2010] [Revised: 03/08/2011] [Accepted: 03/29/2011] [Indexed: 05/13/2023]
Abstract
Growing problems of pyrethroid resistance in Anopheles funestus have intensified efforts to identify alternative insecticides. Many agrochemicals target the GABA receptors, but cross-resistance from dieldrin resistance may preclude their introduction. Dieldrin resistance was detected in An. funestus populations from West (Burkina Faso) and central (Cameroon) Africa, but populations from East (Uganda) and Southern Africa (Mozambique and Malawi) were fully susceptible to this insecticide. Partial sequencing of the dieldrin target site, the γ-aminobutyric acid (GABA) receptor, identified two amino acid substitutions, A296S and V327I. The A296S mutation has been associated with dieldrin resistance in other species. The V327I mutations was detected in the resistant sample from Burkina Faso and Cameroon and consistently associated with the A296S substitution. The full-length of the An. funestus GABA-receptor gene, amplified by RT-PCR, generated a sequence of 1674 bp encoding 557 amino acid of the protein in An. funestus with 98% similarity to that of Anopheles gambiae. Two diagnostic assays were developed to genotype the A296S mutation (pyrosequencing and PCR-RFLP), and use of these assays revealed high frequency of the resistant allele in Burkina Faso (60%) and Cameroon (82%), moderate level in Benin (16%) while low frequency or absence of the mutation was observed respectively in Uganda (7.5%) or 0% in Malawi and Mozambique. The distribution of the Rdl(R) mutation in An. funestus populations in Africa suggests extensive barriers to gene flow between populations from different regions.
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Affiliation(s)
- Charles S Wondji
- Vector Group, Liverpool School of Tropical Medicine, Pembroke Place, Liverpool L3 5QA, United Kingdom.
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23
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Brooke BD, Koekemoer LL. Major effect genes or loose confederations? The development of insecticide resistance in the malaria vector Anopheles gambiae. Parasit Vectors 2010; 3:74. [PMID: 20716346 PMCID: PMC2930636 DOI: 10.1186/1756-3305-3-74] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2010] [Accepted: 08/17/2010] [Indexed: 11/10/2022] Open
Abstract
Insecticide use in public health and agriculture presents a dramatic adaptive challenge to target and non-target insect populations. The rapid development of genetically modulated resistance to insecticides is postulated to develop in two distinct ways: By selection for single major effect genes or by selection for loose confederations in which several factors, not normally associated with each other, inadvertently combine their effects to produce resistance phenotypes. Insecticide resistance is a common occurrence and has been intensively studied in the major malaria vector Anopheles gambiae, providing a useful model for examining how insecticide resistance develops and what pleiotropic effects are likely to emerge as a consequence of resistance. As malaria vector control becomes increasingly reliant on successfully managing insecticide resistance, the characterisation of resistance mechanisms and their pleiotropic effects becomes increasingly important.
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Affiliation(s)
- Basil D Brooke
- Malaria Entomology Research Unit, School of Pathology of the University of the Witwatersrand and the National Health Laboratory Service, Johannesburg, South Africa.
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24
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Benedict MQ, Knols BGJ, Bossin HC, Howell PI, Mialhe E, Caceres C, Robinson AS. Colonisation and mass rearing: learning from others. Malar J 2009; 8 Suppl 2:S4. [PMID: 19917074 PMCID: PMC2777326 DOI: 10.1186/1475-2875-8-s2-s4] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Mosquitoes, just as other insects produced for the sterile insect technique (SIT), are subjected to several unnatural processes including laboratory colonisation and large-scale factory production. After these processes, sterile male mosquitoes must perform the natural task of locating and mating with wild females. Therefore, the colonisation and production processes must preserve characters necessary for these functions. Fortunately, in contrast to natural selection which favours a suite of characteristics that improve overall fitness, colonisation and production practices for SIT strive to maximize only the few qualities that are necessary to effectively control populations. However, there is considerable uncertainty about some of the appropriate characteristics due to the lack of data. Development of biological products for other applications suggest that it is possible to identify and modify competitiveness characteristics in order to produce competitive mass produced sterile mosquitoes. This goal has been pursued - and sometimes achieved - by mosquito colonisation, production, and studies that have linked these characteristics to field performance. Parallels are drawn to studies in other insect SIT programmes and aquaculture which serve as vital technical reference points for mass-production of mosquitoes, most of whose development occurs - and characteristics of which are determined - in an aquatic environment. Poorly understood areas that require further study are numerous: diet, mass handling and genetic and physiological factors that influence mating competitiveness. Compromises in such traits due to demands to increase numbers or reduce costs, should be carefully considered in light of the desired field performance.
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Affiliation(s)
- Mark Q Benedict
- Entomology Unit, FAO/IAEA Agriculture and Biotechnology Laboratory, IAEA Laboratories, A-2444 Seibersdorf, Austria.
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25
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Gray EM, Rocca KAC, Costantini C, Besansky NJ. Inversion 2La is associated with enhanced desiccation resistance in Anopheles gambiae. Malar J 2009; 8:215. [PMID: 19772577 PMCID: PMC2754996 DOI: 10.1186/1475-2875-8-215] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2009] [Accepted: 09/21/2009] [Indexed: 11/25/2022] Open
Abstract
Background Anopheles gambiae, the principal vector of malignant malaria in Africa, occupies a wide range of habitats. Environmental flexibility may be conferred by a number of chromosomal inversions non-randomly associated with aridity, including 2La. The purpose of this study was to determine the physiological mechanisms associated with the 2La inversion that may result in the preferential survival of its carriers in hygrically-stressful environments. Methods Two homokaryotypic populations of A. gambiae (inverted 2La and standard 2L+a) were created from a parental laboratory colony polymorphic for 2La and standard for all other known inversions. Desiccation resistance, water, energy and dry mass of adult females of both populations were compared at several ages and following acclimation to a more arid environment. Results Females carrying 2La were significantly more resistant to desiccation than 2L+a females at emergence and four days post-emergence, for different reasons. Teneral 2La females had lower rates of water loss than their 2L+a counterparts, while at four days, 2La females had higher initial water content. No differences in desiccation resistance were found at eight days, with or without acclimation. However, acclimation resulted in both populations significantly reducing their rates of water loss and increasing their desiccation resistance. Acclimation had contrasting effects on the body characteristics of the two populations: 2La females boosted their glycogen stores and decreased lipids, whereas 2La females did the contrary. Conclusion Variation in rates of water loss and response to acclimation are associated with alternative arrangements of the 2La inversion. Understanding the mechanisms underlying these traits will help explain how inversion polymorphisms permit exploitation of a heterogeneous environment by this disease vector.
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Affiliation(s)
- Emilie M Gray
- Eck Institute for Global Health, Department of Biological Sciences, University of Notre Dame, Notre Dame, IN, USA.
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26
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Ng'habi KR, Meneses CR, Cornel AJ, Slotman MA, Knols BG, Ferguson HM, Lanzaro GC. Clarification of anomalies in the application of a 2La molecular karyotyping method for the malaria vector Anopheles gambiae. Parasit Vectors 2008; 1:45. [PMID: 19091112 PMCID: PMC2628339 DOI: 10.1186/1756-3305-1-45] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2008] [Accepted: 12/17/2008] [Indexed: 11/15/2022] Open
Abstract
Background Chromosomal inversions have been considered to be potentially important barriers to gene flow in many groups of animals through their effect on recombination suppression in heterokaryotypic individuals. Inversions can also enhance local adaptation in different groups of organisms and may often represent species-specific differences among closely related taxa. We conducted a study to characterize the 2La inversion karyotypes of An. gambiae sensu stricto mosquitoes sampled from the Kilombero Valley (Tanzania) using a newly designed PCR assay. Results We frequently encountered a (687 bp) fragment which was only present in the Kilombero Valley populations. Laboratory crossing between An. gambiae s.s. from Njage (Tanzania) and Kisumu (Western Kenya) populations resulted in F1 offspring carrying the observed fragment. Karyotype analysis did not indicate differences in 2La region chromosome morphology between individuals carrying the PCR fragments, the 207 bp fragment, or the 687 bp fragement. Conclusion The observed insertion/deletion polymorphism within the region amplified by the 2La PCR diagnostic test may confound the interpretation of this assay and should be well considered in order to maintain an acceptable level of reliability in studies using this assay to describe the distribution and frequency of the 2La inversion among natural populations of An. gambiae s.s.
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Affiliation(s)
- Kija R Ng'habi
- Ifakara Health Institute, Mlabani Passage, Ifakara, Tanzania.
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27
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Hoffmann AA, Rieseberg LH. Revisiting the Impact of Inversions in Evolution: From Population Genetic Markers to Drivers of Adaptive Shifts and Speciation? ANNUAL REVIEW OF ECOLOGY EVOLUTION AND SYSTEMATICS 2008; 39:21-42. [PMID: 20419035 DOI: 10.1146/annurev.ecolsys.39.110707.173532] [Citation(s) in RCA: 414] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
There is a growing appreciation that chromosome inversions affect rates of adaptation, speciation, and the evolution of sex chromosomes. Comparative genomic studies have identified many new paracentric inversion polymorphisms. Population models suggest that inversions can spread by reducing recombination between alleles that independently increase fitness, without epistasis or coadaptation. Areas of linkage disequilibrium extend across large inversions but may be interspersed by areas with little disequilibrium. Genes located within inversions are associated with a variety of traits including those involved in climatic adaptation. Inversion polymorphisms may contribute to speciation by generating underdominance owing to inviable gametes, but an alternative view gaining support is that inversions facilitate speciation by reducing recombination, protecting genomic regions from introgression. Likewise, inversions may facilitate the evolution of sex chromosomes by reducing recombination between sex determining alleles and alleles with sex-specific effects. However, few genes within inversions responsible for fitness effects or speciation have been identified.
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Affiliation(s)
- Ary A Hoffmann
- Centre for Environmental Stress and Adaptation Research, Department of Genetics, University of Melbourne, Parkville, Victoria 3010 Australia;
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28
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Brooke BD, Hunt RH, Matambo TS, Koekemoer LL, Van Wyk P, Coetzee M. Dieldrin resistance in the malaria vector Anopheles gambiae in Ghana. MEDICAL AND VETERINARY ENTOMOLOGY 2006; 20:294-9. [PMID: 17044880 DOI: 10.1111/j.1365-2915.2006.00639.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
Anopheles gambiae Giles s.s. (Diptera: Culicidae) is one of the principal vectors of malaria in the Ashanti region of central Ghana. High levels of resistance to dieldrin were recorded in a wild-caught sample from Obuasi (south of Kumasi) as well as a laboratory colony established using material from the wild population. Cytogenetic analysis of wild-caught and laboratory samples revealed chromosomal polymorphism for inversions 2La and 2Rb. Although inversion 2La has previously been shown to be associated with dieldrin resistance in certain other laboratory strains originating from West Africa, there was no obvious association between inversion karyotype assortment and the resistance phenotype in the Obuasi population. In addition, polymerase chain reaction analysis indicated the presence of the alanine296 to glycine mutation in the GABA (gamma amino-butyric acid) receptor (which has been mapped to a chromosomal position within inversion 2La). This mutation has previously been shown to be associated with dieldrin resistance in the same An. gambiae laboratory strains of West African origin. Our data show only a weak association between the dieldrin resistance phenotype and the presence of this mutation, suggesting that another dieldrin resistance mechanism is operational in the Obuasi population. Biochemical and synergist exposure assays suggest a metabolic component, probably mediated by monooxygenase P450 enzymes. We conclude that dieldrin resistance in the An. gambiae population of the Obuasi region occurs at a high level - most likely in the absence of selection - and that control of the resistance phenotype is polyfactorial and must include components other than mutations in the GABA receptor locus.
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Affiliation(s)
- B D Brooke
- Vector Control Reference Unit, National Institute for Communicable Diseases, Sandringham, South Africa.
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29
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Vatandoost H, Oshaghi MA, Abaie MR, Shahi M, Yaaghoobi F, Baghaii M, Hanafi-Bojd AA, Zamani G, Townson H. Bionomics of Anopheles stephensi Liston in the malarious area of Hormozgan province, southern Iran, 2002. Acta Trop 2006; 97:196-203. [PMID: 16329986 DOI: 10.1016/j.actatropica.2005.11.002] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2005] [Revised: 10/17/2005] [Accepted: 11/07/2005] [Indexed: 10/25/2022]
Abstract
Anopheles stephensi Liston is an important malaria vector in Hormozgan province, where it is the most prevalent anopheline mosquito. It shows two annual activity peaks, one in spring and another in the autumn. In mountainous areas the second peak starts earlier than in coastal regions. Adults are endophilic and endophagic, but in the hot season when people sleep outside buildings they frequently bite outdoors. Larvae are found in a wide-range of habitats, both natural and man-made. All three biological forms of the species, occur in the province, i.e. An. stephensi stephensi (type form), An. stephensi mysorensis, and the intermediate form. An. stephensi mysorensis is found only in rural-mountainous areas, whereas the type and intermediate forms occur in urban-coastal regions and the rural plains, with the type form predominant. The presence of the type form in urban areas and mysorensis in rural areas is consistent with the available epidemiological data for malaria in the region and with the finding in India that the type form is an efficient malaria vector inhabiting urban areas whereas mysorensis is rural and has a lower vectorial capacity. Insecticide susceptibility tests on field collected adult mysorensis and adults from laboratory strains of the type and intermediate forms were carried out according to WHO standard methods. These showed that all three forms are susceptible to bendiocarb, propoxur, malathion, fenitrothion, deltamethrin, permethrin, cyfluthrin, and lambdacyhalothrin, but are resistant to DDT and show low level of tolerance to dieldrin. Examination of the larvicidal activity of malathion, fenitrothion, temephos and chlorpyrifos at diagnostic doses showed that these stephensi forms are susceptible to all larvicides except fenitrothion. Irritability tests to pyrethroid insecticides showed high levels of irritability to permethrin and lambdacyhalothrin, but low irritability to cyfluthrin and deltamethrin. The importance of these findings for the epidemiology and control of malaria in the region are discussed.
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Affiliation(s)
- H Vatandoost
- Department of Medical Entomology, School of Public Health & Institute of Public Health Research, Tehran University of Medical Science, P.O. Box 6446-14155, Tehran, Iran
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30
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Du W, Awolola TS, Howell P, Koekemoer LL, Brooke BD, Benedict MQ, Coetzee M, Zheng L. Independent mutations in the Rdl locus confer dieldrin resistance to Anopheles gambiae and An. arabiensis. INSECT MOLECULAR BIOLOGY 2005; 14:179-183. [PMID: 15796751 DOI: 10.1111/j.1365-2583.2005.00544.x] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Substitutions of a conserved alanine residue in the Rdl locus coding for a gamma-aminobutyric acid (GABA) receptor subunit with serine or glycine confer resistance to dieldrin in various insect species. Here, we show that alanine to glycine substitution in the Rdl locus of the malaria vector, Anopheles gambiae, is genetically linked to resistance to dieldrin. An alanine to serine substitution developed independently in a dieldrin resistant strain of An. arabiensis. An allele-specific polymerase chain reaction (PCR) assay was able to differentiate dieldrin resistant and susceptible mosquitoes.
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Affiliation(s)
- W Du
- Yale University School of Medicine, Epidemiology and Public Health, New Haven, CT 06520, USA
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