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Krzywinska E, Ribeca P, Ferretti L, Hammond A, Krzywinski J. A novel factor modulating X chromosome dosage compensation in Anopheles. Curr Biol 2023; 33:4697-4703.e4. [PMID: 37774706 DOI: 10.1016/j.cub.2023.09.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2023] [Revised: 08/31/2023] [Accepted: 09/01/2023] [Indexed: 10/01/2023]
Abstract
Dosage compensation (DC), a process countering chromosomal imbalance in individuals with heteromorphic sex chromosomes, has been molecularly characterized only in mammals, Caenorhabditis elegans, and fruit flies.1 In Drosophila melanogaster males, it is achieved by an approximately 2-fold hypertranscription of the monosomic X chromosome mediated by the MSL complex.2,3 The complex is not assembled on female X chromosomes because production of its key protein MSL-2 is prevented due to intron retention and inhibition of translation by Sex-lethal, a female-specific protein operating at the top of the sex determination pathway.4 It remains unclear how DC is mechanistically regulated in other insects. In the malaria mosquito Anopheles gambiae, an approximately 2-fold hypertranscription of the male X also occurs5 by a yet-unknown molecular mechanism distinct from that in D. melanogaster.6 Here we show that a male-specifically spliced gene we call 007, which arose by a tandem duplication in the Anopheles ancestral lineage, is involved in the control of DC in males. Homozygous 007 knockouts lead to a global downregulation of the male X, phenotypically manifested by a slower development compared to wild-type mosquitoes or mutant females-however, without loss of viability or fertility. In females, a 007 intron retention promoted by the sex determination protein Femaleless, known to prevent hypertranscription from both X chromosomes,7 introduces a premature termination codon apparently rendering the female transcripts non-productive. In addition to providing a unique perspective on DC evolution, the 007, with its conserved properties, may represent an important addition to a genetic toolbox for malaria vector control.
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Affiliation(s)
| | - Paolo Ribeca
- The Pirbright Institute, Ash Road, Pirbright, Surrey GU24 0NF, UK; National Infection Service, UK Health Security Agency, Colindale Avenue, London NW9 5EQ, UK
| | - Luca Ferretti
- Big Data Institute, Nuffield Department of Medicine, University of Oxford, Old Road Campus, Oxford OX3 7LF, UK
| | - Andrew Hammond
- Department of Life Sciences, Imperial College, Exhibition Road, London SW7 2AZ, UK; Biocentis, S.r.l., Via Mazzieri, 05100 Terni, Italy
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2
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Tandonnet S, Krsticevic F, Basika T, Papathanos PA, Torres TT, Scott MJ. A chromosomal-scale reference genome of the New World Screwworm, Cochliomyia hominivorax. DNA Res 2022; 30:6825375. [PMID: 36370138 PMCID: PMC9835758 DOI: 10.1093/dnares/dsac042] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 09/23/2022] [Accepted: 11/10/2022] [Indexed: 11/13/2022] Open
Abstract
The New World Screwworm, Cochliomyia hominivorax (Calliphoridae), is the most important myiasis-causing species in America. Screwworm myiasis is a zoonosis that can cause severe lesions in livestock, domesticated and wild animals, and occasionally in people. Beyond the sanitary problems associated with this species, these infestations negatively impact economic sectors, such as the cattle industry. Here, we present a chromosome-scale assembly of C. hominivorax's genome, organized in 6 chromosome-length and 515 unplaced scaffolds spanning 534 Mb. There was a clear correspondence between the D. melanogaster linkage groups A-E and the chromosomal-scale scaffolds. Chromosome quotient (CQ) analysis identified a single scaffold from the X chromosome that contains most of the orthologs of genes that are on the D. melanogaster fourth chromosome (linkage group F or dot chromosome). CQ analysis also identified potential X and Y unplaced scaffolds and genes. Y-linkage for selected regions was confirmed by PCR with male and female DNA. Some of the long chromosome-scale scaffolds include Y-linked sequences, suggesting misassembly of these regions. These resources will provide a basis for future studies aiming at understanding the biology and evolution of this devastating obligate parasite.
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Affiliation(s)
- Sophie Tandonnet
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo (USP), São Paulo, SP 05508-090, Brazil
| | - Flavia Krsticevic
- Department of Entomology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Tatiana Basika
- Present address: Pasteur+INIA Joint Unit, Institut Pasteur de Montevideo, Mataojo 2020, CP 11400 Montevideo Uruguay
| | - Philippos A Papathanos
- Department of Entomology, Robert H. Smith Faculty of Agriculture, Food and Environment, Hebrew University of Jerusalem, Rehovot 7610001, Israel
| | - Tatiana T Torres
- Departamento de Genética e Biologia Evolutiva, Instituto de Biociências, Universidade de São Paulo (USP), São Paulo, SP 05508-090, Brazil
| | - Maxwell J Scott
- To whom correspondence should be addressed. Tel: +1 919 515 0275; Fax: +1 919 515 7716.
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Yamamoto A, Yadav AK, Scott MJ. Evaluation of Additional Drosophila suzukii Male-Only Strains Generated Through Remobilization of an FL19 Transgene. Front Bioeng Biotechnol 2022; 10:829620. [PMID: 35372301 PMCID: PMC8965018 DOI: 10.3389/fbioe.2022.829620] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2021] [Accepted: 01/27/2022] [Indexed: 12/03/2022] Open
Abstract
Drosophila suzukii (D. suzukii) (Matsumura, 1931; Diptera: Drosophilidae), also known as spotted wing Drosophila, is a worldwide pest of fruits with soft skins such as blueberries and cherries. Originally from Asia, D. suzukii is now present in the Americas and Europe and has become a significant economic pest. Growers largely rely on insecticides for the control of D. suzukii. Genetic strategies offer a species-specific environmentally friendly way for suppression of D. suzukii populations. We previously developed a transgenic strain of D. suzukii that produced only males on a diet that did not contain tetracycline. The strain carried a single copy of the FL19 construct on chromosome 3. Repeated releases of an excess of FL19 males led to suppression of D. suzukii populations in laboratory cage trials. Females died as a consequence of overexpression of the tetracycline transactivator (tTA) and tTA-activated expression of the head involution defective proapoptotic gene. The aim of this study was to generate additional male-only strains that carried two copies of the FL19 transgene through crossing the original line with a piggyBac jumpstarter strain. Males that carried either two chromosome 3 or a singleX-linked transgene were identified through stronger expression of the red fluorescent protein marker gene. The brighter fluorescence of the X-linked lines was likely due to dosage compensation of the red fluorescent protein gene. In total, four X-linked lines and eleven lines with two copies on chromosome 3 were obtained, of which five were further examined. All but one of the strains produced only males on a diet without tetracycline. When crossed with wild type virgin females, all of the five two copy autosomal strains examined produced only males. However, the single copy X-linked lines did not show dominant female lethality. Five of the autosomal lines were further evaluated for productivity (egg to adult) and male competition. Based on these results, the most promising lines have been selected for future population suppression experiments with strains from different geographical locations.
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Paulo DF, Williamson ME, Scott MJ. CRISPR/Cas9 Genome Editing in the New World Screwworm and Australian Sheep Blowfly. Methods Mol Biol 2022; 2495:173-201. [PMID: 35696034 DOI: 10.1007/978-1-0716-2301-5_10] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Blowflies are of interest for medical applications (maggot therapy), forensic investigations, and for evolutionary developmental studies such as the evolution of parasitism. It is because of the latter that some blowflies such as the New World screwworm and the Australian sheep blowfly are considered major economic pests of livestock. Due to their importance, annotated assembled genomes for several species are now available. Here, we present a detailed guide for using the Streptococcus pyogenes Cas9 RNA-guided nuclease to efficiently generate both knockout and knock-in mutations in screwworm and sheep blowfly. These methods should accelerate genetic investigations in these and other closely related species and lead to a better understanding of the roles of selected genes in blowfly development and behavior.
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Affiliation(s)
- Daniel F Paulo
- Department of Plant and Environmental Protection Sciences (PEPS), The University of Hawai'i at Mānoa, Honolulu, HI, USA
| | - Megan E Williamson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA
| | - Maxwell J Scott
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh, NC, USA.
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5
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Conditional knockdown of transformer in sheep blow fly suggests a role in repression of dosage compensation and potential for population suppression. PLoS Genet 2021; 17:e1009792. [PMID: 34662332 PMCID: PMC8553175 DOI: 10.1371/journal.pgen.1009792] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 10/28/2021] [Accepted: 08/24/2021] [Indexed: 11/19/2022] Open
Abstract
The transformer (tra) gene is essential for female development in many insect species, including the Australian sheep blow fly, Lucilia cuprina. Sex-specific tra RNA splicing is controlled by Sex lethal (Sxl) in Drosophila melanogaster but is auto-regulated in L. cuprina. Sxl also represses X chromosome dosage compensation in female D. melanogaster. We have developed conditional Lctra RNAi knockdown strains using the tet-off system. Four strains did not produce females on diet without tetracycline and could potentially be used for genetic control of L. cuprina. In one strain, which showed both maternal and zygotic tTA expression, most XX transformed males died at the pupal stage. RNAseq and qRT-PCR analyses of mid-stage pupae showed increased expression of X-linked genes in XX individuals. These results suggest that Lctra promotes somatic sexual differentiation and inhibits X chromosome dosage compensation in female L. cuprina. However, XX flies homozygous for a loss-of-function Lctra knockin mutation were fully transformed and showed high pupal eclosion. Two of five X-linked genes examined showed a significant increase in mRNA levels in XX males. The stronger phenotype in the RNAi knockdown strain could indicate that maternal Lctra expression may be essential for initiation of dosage compensation suppression in female embryos.
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Scott M. Sex Determination and Dosage Compensation: femaleless Is the Link in Anopheles Mosquitoes. Curr Biol 2021; 31:R260-R263. [PMID: 33689728 DOI: 10.1016/j.cub.2021.01.078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
A new study finds that the femaleless gene is essential for sexual development and repression of X-chromosome dosage compensation in the malaria vector Anopheles gambiae. This could provide the basis for a new genetic approach to control this pest.
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Affiliation(s)
- Max Scott
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC 27695-7613, USA.
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Using Moderate Transgene Expression to Improve the Genetic Sexing System of the Australian Sheep Blow Fly Lucilia cuprina. INSECTS 2020; 11:insects11110797. [PMID: 33202756 PMCID: PMC7697711 DOI: 10.3390/insects11110797] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/09/2020] [Accepted: 11/11/2020] [Indexed: 11/24/2022]
Abstract
Simple Summary Populations of pest insects can be suppressed through repeated mass releases of sterilized insects. This is particularly effective if only sterile males are released. We previously developed several genetically modified strains of the Australian sheep blowfly that produce only males when raised on diet that lacked tetracycline. A disadvantage of the some of the engineered strains was that females would lay few eggs unless fed a diet with a low dose of tetracycline. In this study we show that effective male-only strains can be made by combining driver/effector lines that have moderate transgene expression/activity. Furthermore, the strain does not require tetracycline in the adult diet for female fertility. This “moderate expression/activity” strategy could be more generally applied to other pests that can be genetically modified. Abstract The sterile insect technique (SIT) is a promising strategy to control the Australian sheep blow fly Lucilia cuprina, a major pest of sheep. We have previously developed a transgenic embryonic sexing system (TESS) for this pest to facilitate the potential SIT application. TESS carry two transgenes, a tetracycline transactivator (tTA) driver and a tTA-activated pro-apoptotic effector. TESS females die at the embryonic stage unless tetracycline is supplied in the diet. However, undesired female sterility was observed in some TESS strains without tetracycline due to expression of tTA in ovaries. Here we investigate if TESS that combine transgenes with relatively low/moderate expression/activity improves the fertility of TESS females. tTA driver lines were evaluated for tTA expression by quantitative real time PCR and/or by crossing with a tTA-activated RFPex effector line. Fertility and lethality tests showed that a TESS strain containing a driver line with moderate tTA expression and an effector line showing moderate pro-apoptotic activity could recover the fertility of parental females and eliminated all female offspring at the embryonic stage. Consequently, such a strain could be further evaluated for an SIT program for L. cuprina, and such a “moderate strategy” could be considered for the TESS development in other pest species.
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Andere AA, Pimsler ML, Tarone AM, Picard CJ. The genomes of a monogenic fly: views of primitive sex chromosomes. Sci Rep 2020; 10:15728. [PMID: 32978490 PMCID: PMC7519133 DOI: 10.1038/s41598-020-72880-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 09/07/2020] [Indexed: 11/10/2022] Open
Abstract
The production of male and female offspring is often determined by the presence of specific sex chromosomes which control sex-specific expression, and sex chromosomes evolve through reduced recombination and specialized gene content. Here we present the genomes of Chrysomya rufifacies, a monogenic blow fly (females produce female or male offspring, exclusively) by separately sequencing and assembling each type of female and the male. The genomes (> 25X coverage) do not appear to have any sex-linked Muller F elements (typical for many Diptera) and exhibit little differentiation between groups supporting the morphological assessments of C. rufifacies homomorphic chromosomes. Males in this species are associated with a unimodal coverage distribution while females exhibit bimodal coverage distributions, suggesting a potential difference in genomic architecture. The presence of the individual-sex draft genomes herein provides new clues regarding the origination and evolution of the diverse sex-determining mechanisms observed within Diptera. Additional genomic analysis of sex chromosomes and sex-determining genes of other blow flies will allow a refined evolutionary understanding of how flies with a typical X/Y heterogametic amphogeny (male and female offspring in similar ratios) sex determination systems evolved into one with a dominant factor that results in single sex progeny in a chromosomally monomorphic system.
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Affiliation(s)
- Anne A. Andere
- Department of Biology, Indiana University- Purdue University Indianapolis, Indianapolis, IN USA
| | - Meaghan L. Pimsler
- Department of Biological Sciences, The University of Alabama, Tuscaloosa, AL USA
| | - Aaron M. Tarone
- Department of Entomology, Texas A&M University, College Station, TX USA
| | - Christine J. Picard
- Department of Biology, Indiana University- Purdue University Indianapolis, Indianapolis, IN USA
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9
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Liu J, Ali M, Zhou Q. Establishment and evolution of heterochromatin. Ann N Y Acad Sci 2020; 1476:59-77. [PMID: 32017156 PMCID: PMC7586837 DOI: 10.1111/nyas.14303] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2019] [Revised: 10/31/2019] [Accepted: 01/02/2020] [Indexed: 12/12/2022]
Abstract
The eukaryotic genome is packaged into transcriptionally active euchromatin and silent heterochromatin, with most studies focused on the former encompassing the majority of protein-coding genes. The recent development of various sequencing techniques has refined this classic dichromatic partition and has better illuminated the composition, establishment, and evolution of this genomic and epigenomic "dark matter" in the context of topologically associated domains and phase-separated droplets. Heterochromatin includes genomic regions that can be densely stained by chemical dyes, which have been shown to be enriched for repetitive elements and epigenetic marks, including H3K9me2/3 and H3K27me3. Heterochromatin is usually replicated late, concentrated at the nuclear periphery or around nucleoli, and usually lacks highly expressed genes; and now it is considered to be as neither genetically inert nor developmentally static. Heterochromatin guards genome integrity against transposon activities and exerts important regulatory functions by targeting beyond its contained genes. Both its nucleotide sequences and regulatory proteins exhibit rapid coevolution between species. In addition, there are dynamic transitions between euchromatin and heterochromatin during developmental and evolutionary processes. We summarize here the ever-changing characteristics of heterochromatin and propose models and principles for the evolutionary transitions of heterochromatin that have been mainly learned from studies of Drosophila and yeast. Finally, we highlight the role of sex chromosomes in studying heterochromatin evolution.
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Affiliation(s)
- Jing Liu
- MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences InstituteZhejiang UniversityHangzhouChina
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
| | - Mujahid Ali
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
| | - Qi Zhou
- MOE Laboratory of Biosystems Homeostasis & Protection, Life Sciences InstituteZhejiang UniversityHangzhouChina
- Department of Molecular Evolution and DevelopmentUniversity of ViennaViennaAustria
- Center for Reproductive Medicine, The 2nd Affiliated Hospital, School of MedicineZhejiang UniversityHangzhouChina
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Furman BLS, Metzger DCH, Darolti I, Wright AE, Sandkam BA, Almeida P, Shu JJ, Mank JE. Sex Chromosome Evolution: So Many Exceptions to the Rules. Genome Biol Evol 2020; 12:750-763. [PMID: 32315410 PMCID: PMC7268786 DOI: 10.1093/gbe/evaa081] [Citation(s) in RCA: 98] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/14/2020] [Indexed: 01/10/2023] Open
Abstract
Genomic analysis of many nonmodel species has uncovered an incredible diversity of sex chromosome systems, making it possible to empirically test the rich body of evolutionary theory that describes each stage of sex chromosome evolution. Classic theory predicts that sex chromosomes originate from a pair of homologous autosomes and recombination between them is suppressed via inversions to resolve sexual conflict. The resulting degradation of the Y chromosome gene content creates the need for dosage compensation in the heterogametic sex. Sex chromosome theory also implies a linear process, starting from sex chromosome origin and progressing to heteromorphism. Despite many convergent genomic patterns exhibited by independently evolved sex chromosome systems, and many case studies supporting these theoretical predictions, emerging data provide numerous interesting exceptions to these long-standing theories, and suggest that the remarkable diversity of sex chromosomes is matched by a similar diversity in their evolution. For example, it is clear that sex chromosome pairs are not always derived from homologous autosomes. In addition, both the cause and the mechanism of recombination suppression between sex chromosome pairs remain unclear, and it may be that the spread of recombination suppression is a more gradual process than previously thought. It is also clear that dosage compensation can be achieved in many ways, and displays a range of efficacy in different systems. Finally, the remarkable turnover of sex chromosomes in many systems, as well as variation in the rate of sex chromosome divergence, suggest that assumptions about the inevitable linearity of sex chromosome evolution are not always empirically supported, and the drivers of the birth-death cycle of sex chromosome evolution remain to be elucidated. Here, we concentrate on how the diversity in sex chromosomes across taxa highlights an equal diversity in each stage of sex chromosome evolution.
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Affiliation(s)
- Benjamin L S Furman
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - David C H Metzger
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Iulia Darolti
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alison E Wright
- Department of Animal and Plant Sciences, University of Sheffield, United Kingdom
| | - Benjamin A Sandkam
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Pedro Almeida
- Department of Genetics, Evolution and Environment, University College London, United Kingdom
| | - Jacelyn J Shu
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Judith E Mank
- Beaty Biodiversity Research Centre, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Genetics, Evolution and Environment, University College London, United Kingdom
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Abstract
Sex chromosomes and sex determining genes can evolve fast, with the sex-linked chromosomes often differing between closely related species. Population genetics theory has been developed and tested to explain the rapid evolution of sex chromosomes and sex determination. However, we do not know why the sex chromosomes are divergent in some taxa and conserved in others. Addressing this question requires comparing closely related taxa with conserved and divergent sex chromosomes to identify biological features that could explain these differences. Cytological karyotypes suggest that muscid flies (e.g., house fly) and blow flies are such a taxonomic pair. The sex chromosomes appear to differ across muscid species, whereas they are conserved across blow flies. Despite the cytological evidence, we do not know the extent to which muscid sex chromosomes are independently derived along different evolutionary lineages. To address that question, we used genomic and transcriptomic sequence data to identify young sex chromosomes in two closely related muscid species, horn fly (Haematobia irritans) and stable fly (Stomoxys calcitrans). We provide evidence that the nascent sex chromosomes of horn fly and stable fly were derived independently from each other and from the young sex chromosomes of the closely related house fly (Musca domestica). We present three different scenarios that could have given rise to the sex chromosomes of horn fly and stable fly, and we describe how the scenarios could be distinguished. Distinguishing between these scenarios in future work could identify features of muscid genomes that promote sex chromosome divergence.
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12
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Meisel RP, Delclos PJ, Wexler JR. The X chromosome of the German cockroach, Blattella germanica, is homologous to a fly X chromosome despite 400 million years divergence. BMC Biol 2019; 17:100. [PMID: 31806031 PMCID: PMC6894488 DOI: 10.1186/s12915-019-0721-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/11/2019] [Indexed: 12/30/2022] Open
Abstract
Background Sex chromosome evolution is a dynamic process that can proceed at varying rates across lineages. For example, different chromosomes can be sex-linked between closely related species, whereas other sex chromosomes have been conserved for > 100 million years. Cases of long-term sex chromosome conservation could be informative of factors that constrain sex chromosome evolution. Cytological similarities between the X chromosomes of the German cockroach (Blattella germanica) and most flies suggest that they may be homologous—possibly representing an extreme case of long-term conservation. Results To test the hypothesis that the cockroach and fly X chromosomes are homologous, we analyzed whole-genome sequence data from cockroaches. We found evidence in both sequencing coverage and heterozygosity that a significant excess of the same genes are on both the cockroach and fly X chromosomes. We also present evidence that the candidate X-linked cockroach genes may be dosage compensated in hemizygous males. Consistent with this hypothesis, three regulators of transcription and chromatin on the fly X chromosome are conserved in the cockroach genome. Conclusions Our results support our hypothesis that the German cockroach shares the same X chromosome as most flies. This may represent the convergent evolution of the X chromosome in the lineages leading to cockroaches and flies. Alternatively, the common ancestor of most insects may have had an X chromosome that resembled the extant cockroach and fly X. Cockroaches and flies diverged ∼ 400 million years ago, which would be the longest documented conservation of a sex chromosome. Cockroaches and flies have different mechanisms of sex determination, raising the possibility that the X chromosome was conserved despite the evolution of the sex determination pathway.
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Affiliation(s)
- Richard P Meisel
- Department of Biology and Biochemistry, University of Houston, 3455 Cullen Blvd., Houston, 77204, TX, USA.
| | - Pablo J Delclos
- Department of Biology and Biochemistry, University of Houston, 3455 Cullen Blvd., Houston, 77204, TX, USA
| | - Judith R Wexler
- Department of Ecology and Evolution, University of California, Davis, One Shields Ave, Davis, 95616, CA, USA.,Department of Entomology, University of Maryland, 4112 Plant Sciences Building, College Park, 20742, MD, USA
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13
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Molecular and evolutionary dynamics of animal sex-chromosome turnover. Nat Ecol Evol 2019; 3:1632-1641. [DOI: 10.1038/s41559-019-1050-8] [Citation(s) in RCA: 61] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2019] [Accepted: 10/24/2019] [Indexed: 11/08/2022]
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14
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Yan Y, Williamson ME, Davis RJ, Andere AA, Picard CJ, Scott MJ. Improved transgenic sexing strains for genetic control of the Australian sheep blow fly Lucilia cuprina using embryo-specific gene promoters. Mol Genet Genomics 2019; 295:287-298. [PMID: 31720776 DOI: 10.1007/s00438-019-01622-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Accepted: 11/04/2019] [Indexed: 10/25/2022]
Abstract
For genetic approaches for controlling insect pests such as the sterile insect technique (SIT), it is advantageous to release only males as females are ineffective as control agents and they consume about 50% of the diet. Here we developed tetracycline-repressible Lucilia cuprina transgenic strains in which adult females were fully fertile and viable on a diet that lacked tetracycline and all of their female offspring died at the embryo stage. The transgenic strains are an improvement over the strains we developed previously, which had the disadvantage that adult females on diet without tetracycline were sterile and died prematurely. This was possibly due to the low level expression of the effector gene in ovaries. In the strains developed in this study, the early promoters from L. cuprina nullo or Cochliomyia macellaria CG14427 genes were used to drive the tetracycline transactivator (tTA) expression in the early embryo. In the absence of tetracycline, tTA activates expression of the proapoptotic gene Lshid which contains a female-specific intron. Consequently, only females produce active HID protein and die at the embryo stage. Crossing the tTA-expressing driver lines with an RFPex reporter line confirmed that there was no expression of the effector gene in the ovary. These new embryonic L. cuprina transgenic sexing strains hold great promise for genetic control programs and the system reported here might also be transferable to other major calliphorid livestock pests such as the New World screwworm, Cochliomyia hominivorax.
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Affiliation(s)
- Ying Yan
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA.,Fraunhofer IME-BR, Winchesterstr. 2, 35394, Giessen, Germany
| | - Megan E Williamson
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA
| | - Rebecca J Davis
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA
| | - Anne A Andere
- Fraunhofer IME-BR, Winchesterstr. 2, 35394, Giessen, Germany
| | - Christine J Picard
- Department of Biology, Indiana University Purdue University Indianapolis, Indianapolis, IN, 46202, USA
| | - Maxwell J Scott
- Department of Entomology and Plant Pathology, North Carolina State University, Campus Box 7613, Raleigh, NC, 27695-7613, USA.
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Paulo DF, Williamson ME, Arp AP, Li F, Sagel A, Skoda SR, Sanchez-Gallego J, Vasquez M, Quintero G, Pérez de León AA, Belikoff EJ, Azeredo-Espin AML, McMillan WO, Concha C, Scott MJ. Specific Gene Disruption in the Major Livestock Pests Cochliomyia hominivorax and Lucilia cuprina Using CRISPR/Cas9. G3 (BETHESDA, MD.) 2019; 9:3045-3055. [PMID: 31340950 PMCID: PMC6723136 DOI: 10.1534/g3.119.400544] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2019] [Accepted: 07/23/2019] [Indexed: 02/07/2023]
Abstract
Cochliomyia hominivorax and Lucilia cuprina are major pests of livestock. Their larvae infest warm-blooded vertebrates and feed on host's tissues, resulting in severe industry losses. As they are serious pests, considerable effort has been made to develop genomic resources and functional tools aiming to improve their management and control. Here, we report a significant addition to the pool of genome manipulation tools through the establishment of efficient CRISPR/Cas9 protocols for the generation of directed and inheritable modifications in the genome of these flies. Site-directed mutations were introduced in the C hominivorax and L cuprina yellow genes (ChY and LcY) producing lightly pigmented adults. High rates of somatic mosaicism were induced when embryos were injected with Cas9 ribonucleoprotein complexes (RNPs) pre-assembled with guide RNAs (sgRNAs) at high concentrations. Adult flies carrying disrupted yellow alleles lacked normal pigmentation (brown body phenotype) and efficiently transmitted the mutated alleles to the subsequent generation, allowing the rapid creation of homozygous strains for reverse genetics of candidate loci. We next used our established CRISPR protocol to disrupt the C hominivorax transformer gene (Chtra). Surviving females carrying mutations in the Chtra locus developed mosaic phenotypes of transformed ovipositors with characteristics of male genitalia while exhibiting abnormal reproductive tissues. The CRISPR protocol described here is a significant improvement on the existing toolkit of molecular methods in calliphorids. Our results also suggest that Cas9-based systems targeting Chtra and Lctra could be an effective means for controlling natural populations of these important pests.
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Affiliation(s)
- Daniel F Paulo
- Centre for Molecular Biology and Genetic Engineering, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas
- Laboratory of Ecological and Evolutionary Genomics, Smithsonian Tropical Research Institute, Gamboa, Panama
| | - Megan E Williamson
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh NC
| | - Alex P Arp
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Kerrville TX, and
| | - Fang Li
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh NC
| | - Agustin Sagel
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Screwworm Research Site, Pacora, Panama
| | - Steven R Skoda
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Screwworm Research Site, Pacora, Panama
| | - Joel Sanchez-Gallego
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Screwworm Research Site, Pacora, Panama
| | - Mario Vasquez
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Screwworm Research Site, Pacora, Panama
| | - Gladys Quintero
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Screwworm Research Site, Pacora, Panama
| | - Adalberto A Pérez de León
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory and Veterinary Pest Genomics Center, Kerrville TX, and
| | - Esther J Belikoff
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh NC
| | - Ana M L Azeredo-Espin
- Centre for Molecular Biology and Genetic Engineering, Department of Genetics, Evolution, Microbiology and Immunology, University of Campinas
| | - W Owen McMillan
- Laboratory of Ecological and Evolutionary Genomics, Smithsonian Tropical Research Institute, Gamboa, Panama
| | - Carolina Concha
- Laboratory of Ecological and Evolutionary Genomics, Smithsonian Tropical Research Institute, Gamboa, Panama
| | - Maxwell J Scott
- Department of Entomology and Plant Pathology, North Carolina State University, Raleigh NC
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16
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Qi Y, Wu Y, Saunders R, Chen XG, Mao C, Biedler JK, Tu ZJ. Guy1, a Y-linked embryonic signal, regulates dosage compensation in Anopheles stephensi by increasing X gene expression. eLife 2019; 8:43570. [PMID: 30888319 PMCID: PMC6440743 DOI: 10.7554/elife.43570] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 03/16/2019] [Indexed: 12/22/2022] Open
Abstract
We previously showed that Guy1, a primary signal expressed from the Y chromosome, is a strong candidate for a male-determining factor that confers female-specific lethality in Anopheles stephensi (Criscione et al., 2016). Here, we present evidence that Guy1 increases X gene expression in Guy1-transgenic females from two independent lines, providing a mechanism underlying the Guy1-conferred female lethality. The median level gene expression (MGE) of X-linked genes is significantly higher than autosomal genes in Guy1-transgenic females while there is no significant difference in MGE between X and autosomal genes in wild-type females. Furthermore, Guy1 significantly upregulates at least 40% of the 996 genes across the X chromosome in transgenic females. Guy1-conferred female-specific lethality is remarkably stable and completely penetrant. These findings indicate that Guy1 regulates dosage compensation in An. stephensi and components of dosage compensation may be explored to develop novel strategies to control mosquito-borne diseases.
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Affiliation(s)
- Yumin Qi
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Yang Wu
- Department of Pathogen Biology, School of Public Health, Southern Medical University, Guangdong, China
| | - Randy Saunders
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Xiao-Guang Chen
- Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Chunhong Mao
- Biocomplexity Institute of Virginia Tech, Virginia Tech, Blacksburg, Virginia, United States
| | - James Kite Biedler
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
| | - Zhijian Jake Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, Virginia, United States.,Fralin Life Science Institute, Virginia Tech, Blacksburg, Virginia, United States
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17
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Riddle NC, Elgin SCR. The Drosophila Dot Chromosome: Where Genes Flourish Amidst Repeats. Genetics 2018; 210:757-772. [PMID: 30401762 PMCID: PMC6218221 DOI: 10.1534/genetics.118.301146] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Accepted: 08/17/2018] [Indexed: 11/18/2022] Open
Abstract
The F element of the Drosophila karyotype (the fourth chromosome in Drosophila melanogaster) is often referred to as the "dot chromosome" because of its appearance in a metaphase chromosome spread. This chromosome is distinct from other Drosophila autosomes in possessing both a high level of repetitious sequences (in particular, remnants of transposable elements) and a gene density similar to that found in the other chromosome arms, ∼80 genes distributed throughout its 1.3-Mb "long arm." The dot chromosome is notorious for its lack of recombination and is often neglected as a consequence. This and other features suggest that the F element is packaged as heterochromatin throughout. F element genes have distinct characteristics (e.g, low codon bias, and larger size due both to larger introns and an increased number of exons), but exhibit expression levels comparable to genes found in euchromatin. Mapping experiments show the presence of appropriate chromatin modifications for the formation of DNaseI hypersensitive sites and transcript initiation at the 5' ends of active genes, but, in most cases, high levels of heterochromatin proteins are observed over the body of these genes. These various features raise many interesting questions about the relationships of chromatin structures with gene and chromosome function. The apparent evolution of the F element as an autosome from an ancestral sex chromosome also raises intriguing questions. The findings argue that the F element is a unique chromosome that occupies its own space in the nucleus. Further study of the F element should provide new insights into chromosome structure and function.
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Affiliation(s)
- Nicole C Riddle
- Department of Biology, The University of Alabama at Birmingham, Alabama 35294
| | - Sarah C R Elgin
- Department of Biology, Washington University in St. Louis, Missouri 63130
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