1
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Kitaoka M, Yamashita YM. Running the gauntlet: challenges to genome integrity in spermiogenesis. Nucleus 2024; 15:2339220. [PMID: 38594652 PMCID: PMC11005813 DOI: 10.1080/19491034.2024.2339220] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2024] [Accepted: 04/02/2024] [Indexed: 04/11/2024] Open
Abstract
Species' continuity depends on gametogenesis to produce the only cell types that can transmit genetic information across generations. Spermiogenesis, which encompasses post-meiotic, haploid stages of male gametogenesis, is a process that leads to the formation of sperm cells well-known for their motility. Spermiogenesis faces three major challenges. First, after two rounds of meiotic divisions, the genome lacks repair templates (no sister chromatids, no homologous chromosomes), making it incredibly vulnerable to any genomic insults over an extended time (typically days-weeks). Second, the sperm genome becomes transcriptionally silent, making it difficult to respond to new perturbations as spermiogenesis progresses. Third, the histone-to-protamine transition, which is essential to package the sperm genome, counterintuitively involves DNA break formation. How spermiogenesis handles these challenges remains poorly understood. In this review, we discuss each challenge and their intersection with the biology of protamines. Finally, we discuss the implication of protamines in the process of evolution.
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Affiliation(s)
- Maiko Kitaoka
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, Cambridge, MA, USA
| | - Yukiko M. Yamashita
- Whitehead Institute for Biomedical Research and Howard Hughes Medical Institute, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
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2
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Swanepoel CM, Mueller JL. Out with the old, in with the new: Meiotic driving of sex chromosome evolution. Semin Cell Dev Biol 2024; 163:14-21. [PMID: 38664120 PMCID: PMC11351068 DOI: 10.1016/j.semcdb.2024.04.004] [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: 11/08/2023] [Revised: 04/19/2024] [Accepted: 04/20/2024] [Indexed: 05/26/2024]
Abstract
Chromosomal regions with meiotic drivers exhibit biased transmission (> 50 %) over their competing homologous chromosomal region. These regions often have two prominent genetic features: suppressed meiotic crossing over and rapidly evolving multicopy gene families. Heteromorphic sex chromosomes (e.g., XY) often share these two genetic features with chromosomal regions exhibiting meiotic drive. Here, we discuss parallels between meiotic drive and sex chromosome evolution, how the divergence of heteromorphic sex chromosomes can be influenced by meiotic drive, experimental approaches to study meiotic drive on sex chromosomes, and meiotic drive in traditional and non-traditional model organisms with high-quality genome assemblies. The newly available diversity of high-quality sex chromosome sequences allows us to revisit conventional models of sex chromosome evolution through the lens of meiotic drive.
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Affiliation(s)
- Callie M Swanepoel
- Department of Human Genetics, University of Michigan Medical School, 1241 E. Catherine St, Ann Arbor, MI, USA
| | - Jacob L Mueller
- Department of Human Genetics, University of Michigan Medical School, 1241 E. Catherine St, Ann Arbor, MI, USA.
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3
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López Hernández JF, Rubinstein BY, Unckless RL, Zanders SE. Modeling the evolution of Schizosaccharomyces pombe populations with multiple killer meiotic drivers. G3 (BETHESDA, MD.) 2024; 14:jkae142. [PMID: 38938172 DOI: 10.1093/g3journal/jkae142] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2024] [Revised: 05/23/2024] [Accepted: 06/03/2024] [Indexed: 06/29/2024]
Abstract
Meiotic drivers are selfish genetic loci that can be transmitted to more than half of the viable gametes produced by a heterozygote. This biased transmission gives meiotic drivers an evolutionary advantage that can allow them to spread over generations until all members of a population carry the driver. This evolutionary power can also be exploited to modify natural populations using synthetic drivers known as "gene drives." Recently, it has become clear that natural drivers can spread within genomes to birth multicopy gene families. To understand intragenomic spread of drivers, we model the evolution of 2 or more distinct meiotic drivers in a population. We employ the wtf killer meiotic drivers from Schizosaccharomyces pombe, which are multicopy in all sequenced isolates, as models. We find that a duplicate wtf driver identical to the parent gene can spread in a population unless, or until, the original driver is fixed. When the duplicate driver diverges to be distinct from the parent gene, we find that both drivers spread to fixation under most conditions, but both drivers can be lost under some conditions. Finally, we show that stronger drivers make weaker drivers go extinct in most, but not all, polymorphic populations with absolutely linked drivers. These results reveal the strong potential for natural meiotic drive loci to duplicate and diverge within genomes. Our findings also highlight duplication potential as a factor to consider in the design of synthetic gene drives.
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Affiliation(s)
| | - Boris Y Rubinstein
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
| | - Robert L Unckless
- Department of Molecular Biosciences, University of Kansas, 1200 Sunnyside Avenue, Lawrence, KS 66045, USA
| | - Sarah E Zanders
- Stowers Institute for Medical Research, 1000 East 50th Street, Kansas City, MO 64110, USA
- Department of Cell Biology and Physiology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160, USA
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4
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Chen P, Pan KC, Park EH, Luo Y, Lee YCG, Aravin AA. Escalation of genome defense capacity enables control of an expanding meiotic driver. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.06.12.598716. [PMID: 38915551 PMCID: PMC11195268 DOI: 10.1101/2024.06.12.598716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/26/2024]
Abstract
From RNA interference to chromatin silencing, diverse genome defense pathways silence selfish genetic elements to safeguard genome integrity1,2. Despite their diversity, different defense pathways share a modular organization, where numerous specificity factors identify diverse targets and common effectors silence them. In the PIWI-interacting RNA (piRNA) pathway, which controls selfish elements in the metazoan germline, diverse target RNAs are first identified by complementary base pairing with piRNAs and then silenced by PIWI-clade nucleases via enzymatic cleavage1,3. Such a binary architecture allows the defense systems to be readily adaptable, where new targets can be captured via the innovation of new specificity factors4,5. Thus, our current understanding of genome defense against lineage-specific selfish genes has been largely limited to the evolution of specificity factors, while it remains poorly understood whether other types of innovations are required. Here, we describe a new type of innovation, which escalates the defense capacity of the piRNA pathway to control a recently expanded selfish gene in Drosophila melanogaster. Through an in vivo RNAi screen for repressors of Stellate-a recently evolved and expanded selfish meiotic driver6-8-we discovered a novel defense factor, Trailblazer. Trailblazer is a transcription factor that promotes the expression of two PIWI-clade nucleases, Aub and AGO3, to match Stellate in abundance. Recent innovation in the DNA-binding domain of Trailblazer enabled it to drastically elevate Aub and AGO3 expression in the D. melanogaster lineage, thereby escalating the silencing capacity of the piRNA pathway to control expanded Stellate and safeguard fertility. As copy-number expansion is a recurrent feature of diverse selfish genes across the tree of life9-12, we envision that augmenting the defense capacity to quantitatively match selfish genes is likely a repeatedly employed defense strategy in evolution.
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Affiliation(s)
- Peiwei Chen
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Katherine C. Pan
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Eunice H. Park
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Yicheng Luo
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
| | - Yuh Chwen G. Lee
- Department of Ecology and Evolutionary Biology, University of California, Irvine, Irvine, California 92697, USA
| | - Alexei A. Aravin
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, California 91125, USA
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5
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Brand CL, Oliver GT, Farkas IZ, Buszczak M, Levine MT. Recurrent Duplication and Diversification of a Vital DNA Repair Gene Family Across Drosophila. Mol Biol Evol 2024; 41:msae113. [PMID: 38865490 PMCID: PMC11210505 DOI: 10.1093/molbev/msae113] [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: 11/07/2023] [Revised: 05/30/2024] [Accepted: 06/04/2024] [Indexed: 06/14/2024] Open
Abstract
Maintaining genome integrity is vital for organismal survival and reproduction. Essential, broadly conserved DNA repair pathways actively preserve genome integrity. However, many DNA repair proteins evolve adaptively. Ecological forces like UV exposure are classically cited drivers of DNA repair evolution. Intrinsic forces like repetitive DNA, which also imperil genome integrity, have received less attention. We recently reported that a Drosophila melanogaster-specific DNA satellite array triggered species-specific, adaptive evolution of a DNA repair protein called Spartan/MH. The Spartan family of proteases cleave hazardous, covalent crosslinks that form between DNA and proteins ("DNA-protein crosslink repair"). Appreciating that DNA satellites are both ubiquitous and universally fast-evolving, we hypothesized that satellite DNA turnover spurs adaptive evolution of DNA-protein crosslink repair beyond a single gene and beyond the D. melanogaster lineage. This hypothesis predicts pervasive Spartan gene family diversification across Drosophila species. To study the evolutionary history of the Drosophila Spartan gene family, we conducted population genetic, molecular evolution, phylogenomic, and tissue-specific expression analyses. We uncovered widespread signals of positive selection across multiple Spartan family genes and across multiple evolutionary timescales. We also detected recurrent Spartan family gene duplication, divergence, and gene loss. Finally, we found that ovary-enriched parent genes consistently birthed functionally diverged, testis-enriched daughter genes. To account for Spartan family diversification, we introduce a novel mechanistic model of antagonistic coevolution that links DNA satellite evolution and adaptive regulation of Spartan protease activity. This framework promises to accelerate our understanding of how DNA repeats drive recurrent evolutionary innovation to preserve genome integrity.
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Affiliation(s)
- Cara L Brand
- Department of Biology and Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Genevieve T Oliver
- Department of Biology and Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Isabella Z Farkas
- Department of Biology and Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Michael Buszczak
- Department of Molecular Biology and Center for Regenerative Science and Medicine, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Mia T Levine
- Department of Biology and Epigenetics Institute, University of Pennsylvania, Philadelphia, PA 19104, USA
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6
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Wei KHC, Chatla K, Bachtrog D. Single-cell RNA-seq of Drosophila miranda testis reveals the evolution and trajectory of germline sex chromosome regulation. PLoS Biol 2024; 22:e3002605. [PMID: 38687805 PMCID: PMC11135767 DOI: 10.1371/journal.pbio.3002605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2022] [Revised: 05/29/2024] [Accepted: 03/27/2024] [Indexed: 05/02/2024] Open
Abstract
Although sex chromosomes have evolved from autosomes, they often have unusual regulatory regimes that are sex- and cell-type-specific such as dosage compensation (DC) and meiotic sex chromosome inactivation (MSCI). The molecular mechanisms and evolutionary forces driving these unique transcriptional programs are critical for genome evolution but have been, in the case of MSCI in Drosophila, subject to continuous debate. Here, we take advantage of the younger sex chromosomes in D. miranda (XR and the neo-X) to infer how former autosomes acquire sex-chromosome-specific regulatory programs using single-cell and bulk RNA sequencing and ribosome profiling, in a comparative evolutionary context. We show that contrary to mammals and worms, the X down-regulation through germline progression is most consistent with the shutdown of DC instead of MSCI, resulting in half gene dosage at the end of meiosis for all 3 X's. Moreover, lowly expressed germline and meiotic genes on the neo-X are ancestrally lowly expressed, instead of acquired suppression after sex linkage. For the young neo-X, DC is incomplete across all tissue and cell types and this dosage imbalance is rescued by contributions from Y-linked gametologs which produce transcripts that are translated to compensate both gene and protein dosage. We find an excess of previously autosomal testis genes becoming Y-specific, showing that the neo-Y and its masculinization likely resolve sexual antagonism. Multicopy neo-sex genes are predominantly expressed during meiotic stages of spermatogenesis, consistent with their amplification being driven to interfere with mendelian segregation. Altogether, this study reveals germline regulation of evolving sex chromosomes and elucidates the consequences these unique regulatory mechanisms have on the evolution of sex chromosome architecture.
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Affiliation(s)
- Kevin H-C. Wei
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, United States of America
- Department of Zoology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kamalakar Chatla
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, United States of America
| | - Doris Bachtrog
- Department of Integrative Biology, University of California Berkeley, Berkeley, California, United States of America
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7
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Courret C, Wei X, Larracuente AM. New perspectives on the causes and consequences of male meiotic drive. Curr Opin Genet Dev 2023; 83:102111. [PMID: 37704518 PMCID: PMC10842977 DOI: 10.1016/j.gde.2023.102111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2023] [Revised: 08/07/2023] [Accepted: 08/09/2023] [Indexed: 09/15/2023]
Abstract
Gametogenesis is vulnerable to selfish genetic elements that bias their transmission to the next generation by cheating meiosis. These so-called meiotic drivers are widespread in plants, animals, and fungi and can impact genome evolution. Here, we summarize recent progress on the causes and consequences of meiotic drive in males, where selfish elements attack vulnerabilities in spermatogenesis. Advances in genomics provide new insights into the organization and dynamics of driving chromosomes in natural populations. Common themes, including small RNAs, gene duplications, and heterochromatin, emerged from these studies. Interdisciplinary approaches combining evolutionary genomics with molecular and cell biology are beginning to unravel the mysteries of drive and suppression mechanisms. These approaches also provide insights into fundamental processes in spermatogenesis and chromatin regulation.
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Affiliation(s)
- Cécile Courret
- Department of Biology, University of Rochester, Rochester, NY 14627, USA. https://twitter.com/@CecileCourret
| | - Xiaolu Wei
- Department of Biology, University of Rochester, Rochester, NY 14627, USA. https://twitter.com/@xiaolu_wei
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8
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Martí E, Larracuente AM. Genetic conflict and the origin of multigene families: implications for sex chromosome evolution. Proc Biol Sci 2023; 290:20231823. [PMID: 37909083 PMCID: PMC10618873 DOI: 10.1098/rspb.2023.1823] [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: 08/13/2023] [Accepted: 10/10/2023] [Indexed: 11/02/2023] Open
Abstract
Sex chromosomes are havens for intragenomic conflicts. The absence of recombination between sex chromosomes creates the opportunity for the evolution of segregation distorters: selfish genetic elements that hijack different aspects of an individual's reproduction to increase their own transmission. Biased (non-Mendelian) segregation, however, often occurs at a detriment to their host's fitness, and therefore can trigger evolutionary arms races that can have major consequences for genome structure and regulation, gametogenesis, reproductive strategies and even speciation. Here, we review an emerging feature from comparative genomic and sex chromosome evolution studies suggesting that meiotic drive is pervasive: the recurrent evolution of paralogous sex-linked gene families. Sex chromosomes of several species independently acquire and co-amplify rapidly evolving gene families with spermatogenesis-related functions, consistent with a history of intragenomic conflict over transmission. We discuss Y chromosome features that might contribute to the tempo and mode of evolution of X/Y co-amplified gene families, as well as their implications for the evolution of complexity in the genome. Finally, we propose a framework that explores the conditions that might allow for recurrent bouts of fixation of drivers and suppressors, in a dosage-sensitive fashion, and therefore the co-amplification of multigene families on sex chromosomes.
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Affiliation(s)
- Emiliano Martí
- Department of Biology, University of Rochester, Rochester, NY 14627, USA
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9
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Lai EC, Vogan AA. Proliferation and dissemination of killer meiotic drive loci. Curr Opin Genet Dev 2023; 82:102100. [PMID: 37625205 PMCID: PMC10900872 DOI: 10.1016/j.gde.2023.102100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 07/20/2023] [Accepted: 07/22/2023] [Indexed: 08/27/2023]
Abstract
Killer meiotic drive elements are selfish genetic entities that manipulate the sexual cycle to promote their own inheritance via destructive means. Two broad classes are sperm killers, typical of animals and plants, and spore killers, which are present in ascomycete fungi. Killer meiotic drive systems operate via toxins that destroy or disable meiotic products bearing the alternative allele. To avoid suicidal autotargeting, cells that bear these selfish elements must either lack the toxin target, or express an antidote. Historically, these systems were presumed to require large nonrecombining haplotypes to link multiple functional interacting loci. However, recent advances on fungal spore killers reveal that numerous systems are enacted by single genes, and similar molecular genetic studies in Drosophila pinpoint individual loci that distort gamete sex. Notably, many meiotic drivers duplicate readily, forming gene families that can have complex interactions within and between species, and providing substrates for their rapid functional diversification. Here, we summarize the known families of meiotic drivers in fungi and fruit flies, and highlight shared principles about their evolution and proliferation that promote the spread of these noxious genes.
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Affiliation(s)
- Eric C Lai
- Developmental Biology Program, Sloan Kettering Institute, 430 East 67th St, ROC-10, New York, NY 10065, USA.
| | - Aaron A Vogan
- Institute of Organismal Biology, Uppsala University, Norbyvägen 18D, Uppsala 752 36, Sweden.
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10
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Kitano J, Yoshida K. Do sex-linked male meiotic drivers contribute to intrinsic hybrid incompatibilities? Recent empirical studies from flies and rodents. Curr Opin Genet Dev 2023; 81:102068. [PMID: 37354886 DOI: 10.1016/j.gde.2023.102068] [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: 03/04/2023] [Revised: 05/29/2023] [Accepted: 05/29/2023] [Indexed: 06/26/2023]
Abstract
Intrinsic hybrid incompatibility is one of the important isolating barriers between species. In organisms with sex chromosomes, intrinsic hybrid incompatibility often follows two rules: Haldane's rule and large-X effects. One explanation for these two rules is that sex chromosomes are hotspots for meiotic drivers that can cause intrinsic hybrid incompatibility between geographically isolated populations. Although this hypothesis seems plausible and several empirical data are consistent with it, we are still unsure whether such mechanisms occur in nature, particularly with respect to speciation with gene flow. Here, we review empirical studies that have investigated the roles of meiotic drive in sex-chromosome evolution and speciation and propose future studies necessary for testing this hypothesis.
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Affiliation(s)
- Jun Kitano
- Ecological Genetics Laboratory, National Institute of Genetics, Mishima 1111, Shizuoka 411-8540, Japan.
| | - Kohta Yoshida
- Ecological Genetics Laboratory, National Institute of Genetics, Mishima 1111, Shizuoka 411-8540, Japan; Department for Integrative Evolutionary Biology, Max Planck Institute for Biology, Max-Planck-Ring 5, 72076 Tübingen, Germany. https://twitter.com/PristionXY
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11
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Reinhardt JA, Baker RH, Zimin AV, Ladias C, Paczolt KA, Werren JH, Hayashi CY, Wilkinson GS. Impacts of Sex Ratio Meiotic Drive on Genome Structure and Function in a Stalk-Eyed Fly. Genome Biol Evol 2023; 15:evad118. [PMID: 37364298 PMCID: PMC10319772 DOI: 10.1093/gbe/evad118] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Revised: 06/02/2023] [Accepted: 06/15/2023] [Indexed: 06/28/2023] Open
Abstract
Stalk-eyed flies in the genus Teleopsis carry selfish genetic elements that induce sex ratio (SR) meiotic drive and impact the fitness of male and female carriers. Here, we assemble and describe a chromosome-level genome assembly of the stalk-eyed fly, Teleopsis dalmanni, to elucidate patterns of divergence associated with SR. The genome contains tens of thousands of transposable element (TE) insertions and hundreds of transcriptionally and insertionally active TE families. By resequencing pools of SR and ST males using short and long reads, we find widespread differentiation and divergence between XSR and XST associated with multiple nested inversions involving most of the SR haplotype. Examination of genomic coverage and gene expression data revealed seven X-linked genes with elevated expression and coverage in SR males. The most extreme and likely drive candidate involves an XSR-specific expansion of an array of partial copies of JASPer, a gene necessary for maintenance of euchromatin and associated with regulation of TE expression. In addition, we find evidence for rapid protein evolution between XSR and XST for testis expressed and novel genes, that is, either recent duplicates or lacking a Dipteran ortholog, including an X-linked duplicate of maelstrom, which is also involved in TE silencing. Overall, the evidence suggests that this ancient XSR polymorphism has had a variety of impacts on repetitive DNA and its regulation in this species.
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Affiliation(s)
| | - Richard H Baker
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York, USA
| | - Aleksey V Zimin
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, Maryland, USA
| | - Chloe Ladias
- Biology Department, State University of New York at Geneseo, Geneseo, New York, USA
| | - Kimberly A Paczolt
- Department of Biology, University of Maryland, College Park, Maryland, USA
| | - John H Werren
- Department of Biology, University of Rochester, Rochester, New York, USA
| | - Cheryl Y Hayashi
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York, USA
| | - Gerald S Wilkinson
- Department of Biology, University of Maryland, College Park, Maryland, USA
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12
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Vedanayagam J, Lin CJ, Papareddy R, Nodine M, Flynt AS, Wen J, Lai EC. Regulatory logic of endogenous RNAi in silencing de novo genomic conflicts. PLoS Genet 2023; 19:e1010787. [PMID: 37343034 DOI: 10.1371/journal.pgen.1010787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2022] [Accepted: 05/17/2023] [Indexed: 06/23/2023] Open
Abstract
Although the biological utilities of endogenous RNAi (endo-RNAi) have been largely elusive, recent studies reveal its critical role in the non-model fruitfly Drosophila simulans to suppress selfish genes, whose unchecked activities can severely impair spermatogenesis. In particular, hairpin RNA (hpRNA) loci generate endo-siRNAs that suppress evolutionary novel, X-linked, meiotic drive loci. The consequences of deleting even a single hpRNA (Nmy) in males are profound, as such individuals are nearly incapable of siring male progeny. Here, comparative genomic analyses of D. simulans and D. melanogaster mutants of the core RNAi factor dcr-2 reveal a substantially expanded network of recently-emerged hpRNA-target interactions in the former species. The de novo hpRNA regulatory network in D. simulans provides insight into molecular strategies that underlie hpRNA emergence and their potential roles in sex chromosome conflict. In particular, our data support the existence of ongoing rapid evolution of Nmy/Dox-related networks, and recurrent targeting of testis HMG Box loci by hpRNAs. Importantly, the impact of the endo-RNAi network on gene expression flips the convention for regulatory networks, since we observe strong derepression of targets of the youngest hpRNAs, but only mild effects on the targets of the oldest hpRNAs. These data suggest that endo-RNAi are especially critical during incipient stages of intrinsic sex chromosome conflicts, and that continual cycles of distortion and resolution may contribute to speciation.
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Affiliation(s)
- Jeffrey Vedanayagam
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
| | - Ching-Jung Lin
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
- Weill Graduate School of Medical Sciences, Weill Cornell Medical College, New York, New York, United States of America
| | - Ranjith Papareddy
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Austria
| | - Michael Nodine
- Gregor Mendel Institute (GMI), Austrian Academy of Sciences, Vienna Biocenter (VBC), Austria
| | - Alex S Flynt
- Cellular and Molecular Biology, University of Southern Mississippi, Hattiesburg, Mississippi, United States of America
| | - Jiayu Wen
- Division of Genome Sciences and Cancer, The John Curtin School of Medical Research The Australian National University, Canberra, Australia
| | - Eric C Lai
- Developmental Biology Program, Sloan Kettering Institute, New York, New York, United States of America
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13
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Dalíková M, Provazníková I, Provazník J, Grof-Tisza P, Pepi A, Nguyen P. The Role of Repetitive Sequences in Repatterning of Major Ribosomal DNA Clusters in Lepidoptera. Genome Biol Evol 2023; 15:evad090. [PMID: 37226278 PMCID: PMC10257491 DOI: 10.1093/gbe/evad090] [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: 05/31/2022] [Revised: 04/27/2023] [Accepted: 05/09/2023] [Indexed: 05/26/2023] Open
Abstract
Genes for major ribosomal RNAs (rDNA) are present in multiple copies mainly organized in tandem arrays. The number and position of rDNA loci can change dynamically and their repatterning is presumably driven by other repetitive sequences. We explored a peculiar rDNA organization in several representatives of Lepidoptera with either extremely large or numerous rDNA clusters. We combined molecular cytogenetics with analyses of second- and third-generation sequencing data to show that rDNA spreads as a transcription unit and reveal association between rDNA and various repeats. Furthermore, we performed comparative long read analyses among the species with derived rDNA distribution and moths with a single rDNA locus, which is considered ancestral. Our results suggest that satellite arrays, rather than mobile elements, facilitate homology-mediated spread of rDNA via either integration of extrachromosomal rDNA circles or ectopic recombination. The latter arguably better explains preferential spread of rDNA into terminal regions of lepidopteran chromosomes as efficiency of ectopic recombination depends on the proximity of homologous sequences to telomeres.
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Affiliation(s)
- Martina Dalíková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
| | - Irena Provazníková
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Jan Provazník
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- European Molecular Biology Laboratory, Heidelberg, Germany
| | - Patrick Grof-Tisza
- Institute of Biology, Laboratory of Evolutionary Entomology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Adam Pepi
- Department of Biology, Tufts University
| | - Petr Nguyen
- Faculty of Science, University of South Bohemia, České Budějovice, Czech Republic
- Institute of Entomology, Biology Centre CAS, České Budějovice, Czech Republic
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14
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Vedanayagam J, Herbette M, Mudgett H, Lin CJ, Lai CM, McDonough-Goldstein C, Dorus S, Loppin B, Meiklejohn C, Dubruille R, Lai EC. Essential and recurrent roles for hairpin RNAs in silencing de novo sex chromosome conflict in Drosophila simulans. PLoS Biol 2023; 21:e3002136. [PMID: 37289846 PMCID: PMC10292708 DOI: 10.1371/journal.pbio.3002136] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 06/26/2023] [Accepted: 04/21/2023] [Indexed: 06/10/2023] Open
Abstract
Meiotic drive loci distort the normally equal segregation of alleles, which benefits their own transmission even in the face of severe fitness costs to their host organism. However, relatively little is known about the molecular identity of meiotic drivers, their strategies of action, and mechanisms that can suppress their activity. Here, we present data from the fruitfly Drosophila simulans that address these questions. We show that a family of de novo, protamine-derived X-linked selfish genes (the Dox gene family) is silenced by a pair of newly emerged hairpin RNA (hpRNA) small interfering RNA (siRNA)-class loci, Nmy and Tmy. In the w[XD1] genetic background, knockout of nmy derepresses Dox and MDox in testes and depletes male progeny, whereas knockout of tmy causes misexpression of PDox genes and renders males sterile. Importantly, genetic interactions between nmy and tmy mutant alleles reveal that Tmy also specifically maintains male progeny for normal sex ratio. We show the Dox loci are functionally polymorphic within D. simulans, such that both nmy-associated sex ratio bias and tmy-associated sterility can be rescued by wild-type X chromosomes bearing natural deletions in different Dox family genes. Finally, using tagged transgenes of Dox and PDox2, we provide the first experimental evidence Dox family genes encode proteins that are strongly derepressed in cognate hpRNA mutants. Altogether, these studies support a model in which protamine-derived drivers and hpRNA suppressors drive repeated cycles of sex chromosome conflict and resolution that shape genome evolution and the genetic control of male gametogenesis.
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Affiliation(s)
- Jeffrey Vedanayagam
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
| | - Marion Herbette
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon CNRS UMR5239, Université Claude Bernard Lyon 1, Lyon, France
| | - Holly Mudgett
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Ching-Jung Lin
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- Weill Graduate School of Medical Sciences, Weill Cornell Medical College, New York, New York, United States of America
| | - Chun-Ming Lai
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
| | | | - Stephen Dorus
- Center for Reproductive Evolution, Syracuse University, Syracuse, New York, United States of America
| | - Benjamin Loppin
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon CNRS UMR5239, Université Claude Bernard Lyon 1, Lyon, France
| | - Colin Meiklejohn
- School of Biological Sciences, University of Nebraska, Lincoln, Nebraska, United States of America
| | - Raphaëlle Dubruille
- Laboratoire de Biologie et Modélisation de la Cellule, École Normale Supérieure de Lyon CNRS UMR5239, Université Claude Bernard Lyon 1, Lyon, France
| | - Eric C. Lai
- Developmental Biology Program, Sloan-Kettering Institute, New York, New York, United States of America
- Weill Graduate School of Medical Sciences, Weill Cornell Medical College, New York, New York, United States of America
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15
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Park JI, Bell GW, Yamashita YM. Derepression of Y-linked multicopy protamine-like genes interferes with sperm nuclear compaction in D. melanogaster. Proc Natl Acad Sci U S A 2023; 120:e2220576120. [PMID: 37036962 PMCID: PMC10120018 DOI: 10.1073/pnas.2220576120] [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: 12/03/2022] [Accepted: 03/17/2023] [Indexed: 04/12/2023] Open
Abstract
Across species, sperm maturation involves the dramatic reconfiguration of chromatin into highly compact nuclei that enhance hydrodynamic ability and ensure paternal genomic integrity. This process is mediated by the replacement of histones by sperm nuclear basic proteins, also referred to as protamines. In humans, a carefully balanced dosage between two known protamine genes is required for optimal fertility. However, it remains unknown how their proper balance is regulated and how defects in balance may lead to compromised fertility. Here, we show that a nucleolar protein, modulo, a homolog of nucleolin, mediates the histone-to-protamine transition during Drosophila spermatogenesis. We find that modulo mutants display nuclear compaction defects during late spermatogenesis due to decreased expression of autosomal protamine genes (including Mst77F) and derepression of Y-linked multicopy Mst77F homologs (Mst77Y), leading to the mutant's known sterility. Overexpression of Mst77Y in a wild-type background is sufficient to cause nuclear compaction defects, similar to modulo mutant, indicating that Mst77Y is a dominant-negative variant interfering with the process of histone-to-protamine transition. Interestingly, ectopic overexpression of Mst77Y caused decompaction of X-bearing spermatids nuclei more frequently than Y-bearing spermatid nuclei, although this did not greatly affect the sex ratio of offspring. We further show that modulo regulates these protamine genes at the step of transcript polyadenylation. We conclude that the regulation of protamines mediated by modulo, ensuring the expression of functional ones while repressing dominant-negative ones, is critical for male fertility.
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Affiliation(s)
- Jun I. Park
- Life Sciences Institute, University of Michigan, Ann Arbor, MI48109
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, MI48109
- Medical Scientist Training Program, University of Michigan Medical School, Ann Arbor, MI48109
| | - George W. Bell
- Whitehead Institute for Biomedical Research, Cambridge, MA02142
| | - Yukiko M. Yamashita
- Whitehead Institute for Biomedical Research, Cambridge, MA02142
- Department of Biology, School of Science, Massachusetts Institute of Technology, Cambridge, MA02142
- HHMI, Cambridge, MA02142
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16
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Chang CH, Mejia Natividad I, Malik HS. Expansion and loss of sperm nuclear basic protein genes in Drosophila correspond with genetic conflicts between sex chromosomes. eLife 2023; 12:85249. [PMID: 36763410 PMCID: PMC9917458 DOI: 10.7554/elife.85249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Accepted: 01/04/2023] [Indexed: 02/11/2023] Open
Abstract
Many animal species employ sperm nuclear basic proteins (SNBPs) or protamines to package sperm genomes tightly. SNBPs vary across animal lineages and evolve rapidly in mammals. We used a phylogenomic approach to investigate SNBP diversification in Drosophila species. We found that most SNBP genes in Drosophila melanogaster evolve under positive selection except for genes essential for male fertility. Unexpectedly, evolutionarily young SNBP genes are more likely to be critical for fertility than ancient, conserved SNBP genes. For example, CG30056 is dispensable for male fertility despite being one of three SNBP genes universally retained in Drosophila species. We found 19 independent SNBP gene amplification events that occurred preferentially on sex chromosomes. Conversely, the montium group of Drosophila species lost otherwise-conserved SNBP genes, coincident with an X-Y chromosomal fusion. Furthermore, SNBP genes that became linked to sex chromosomes via chromosomal fusions were more likely to degenerate or relocate back to autosomes. We hypothesize that autosomal SNBP genes suppress meiotic drive, whereas sex-chromosomal SNBP expansions lead to meiotic drive. X-Y fusions in the montium group render autosomal SNBPs dispensable by making X-versus-Y meiotic drive obsolete or costly. Thus, genetic conflicts between sex chromosomes may drive SNBP rapid evolution during spermatogenesis in Drosophila species.
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Affiliation(s)
- Ching-Ho Chang
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, United States
| | - Isabel Mejia Natividad
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, United States.,Howard Hughes Medical Institute, Fred Hutchinson Cancer Center, Seattle, United States
| | - Harmit S Malik
- Division of Basic Sciences, Fred Hutchinson Cancer Center, Seattle, United States.,Howard Hughes Medical Institute, Fred Hutchinson Cancer Center, Seattle, United States
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17
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De Carvalho M, Jia GS, Nidamangala Srinivasa A, Billmyre RB, Xu YH, Lange JJ, Sabbarini IM, Du LL, Zanders SE. The wtf meiotic driver gene family has unexpectedly persisted for over 100 million years. eLife 2022; 11:e81149. [PMID: 36227631 PMCID: PMC9562144 DOI: 10.7554/elife.81149] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Accepted: 09/21/2022] [Indexed: 11/21/2022] Open
Abstract
Meiotic drivers are selfish elements that bias their own transmission into more than half of the viable progeny produced by a driver+/driver- heterozygote. Meiotic drivers are thought to exist for relatively short evolutionary timespans because a driver gene or gene family is often found in a single species or in a group of very closely related species. Additionally, drivers are generally considered doomed to extinction when they spread to fixation or when suppressors arise. In this study, we examine the evolutionary history of the wtf meiotic drivers first discovered in the fission yeast Schizosaccharomyces pombe. We identify homologous genes in three other fission yeast species, S. octosporus, S. osmophilus, and S. cryophilus, which are estimated to have diverged over 100 million years ago from the S. pombe lineage. Synteny evidence supports that wtf genes were present in the common ancestor of these four species. Moreover, the ancestral genes were likely drivers as wtf genes in S. octosporus cause meiotic drive. Our findings indicate that meiotic drive systems can be maintained for long evolutionary timespans.
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Affiliation(s)
- Mickaël De Carvalho
- Stowers Institute for Medical ResearchKansas CityUnited States
- Open UniversityMilton KeynesUnited Kingdom
| | - Guo-Song Jia
- PTN Joint Graduate Program, School of Life Sciences, Tsinghua UniversityBeijingChina
- National Institute of Biological Sciences, BeijingBeijingChina
| | - Ananya Nidamangala Srinivasa
- Stowers Institute for Medical ResearchKansas CityUnited States
- Department of Molecular and Integrative Physiology, University of Kansas Medical CenterKansas CityUnited States
| | | | - Yan-Hui Xu
- National Institute of Biological Sciences, BeijingBeijingChina
| | - Jeffrey J Lange
- Stowers Institute for Medical ResearchKansas CityUnited States
| | | | - Li-Lin Du
- National Institute of Biological Sciences, BeijingBeijingChina
- Tsinghua Institute of Multidisciplinary Biomedical Research, Tsinghua UniversityBeijingChina
| | - Sarah E Zanders
- Stowers Institute for Medical ResearchKansas CityUnited States
- Department of Molecular and Integrative Physiology, University of Kansas Medical CenterKansas CityUnited States
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18
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Abstract
Spore killers are specific genetic elements in fungi that kill sexual spores that do not contain them. A range of studies in the last few years have provided the long-awaited first insights into the molecular mechanistic aspects of spore killing in different fungal models, including both yeast-forming and filamentous Ascomycota. Here we describe these recent advances, focusing on the wtf system in the fission yeast Schizosaccharomyces pombe; the Sk spore killers of Neurospora species; and two spore-killer systems in Podospora anserina, Spok and [Het-s]. The spore killers appear thus far mechanistically unrelated. They can involve large genomic rearrangements but most often rely on the action of just a single gene. Data gathered so far show that the protein domains involved in the killing and resistance processes differ among the systems and are not homologous. The emerging picture sketched by these studies is thus one of great mechanistic and evolutionary diversity of elements that cheat during meiosis and are thereby preferentially inherited over sexual generations.
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Affiliation(s)
- Sven J Saupe
- Institut de Biochimie et de Génétique Cellulaire, CNRS UMR 5095, Université de Bordeaux, Bordeaux, France;
| | - Hanna Johannesson
- Department of Organismal Biology, Uppsala University, Uppsala, Sweden;
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19
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Winkler L, Lindholm AK. A meiotic driver alters sperm form and function in house mice: a possible example of spite. Chromosome Res 2022; 30:151-164. [PMID: 35648282 PMCID: PMC9508062 DOI: 10.1007/s10577-022-09695-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2022] [Revised: 03/30/2022] [Accepted: 04/19/2022] [Indexed: 11/03/2022]
Abstract
The ability to subvert independent assortment of chromosomes is found in many meiotic drivers, such as the t haplotype in house mice Mus musculus, in which the t-bearing chromosomal homolog is preferentially transmitted to offspring. This is explained by a poison-antidote system, in which developing + and t sperm in testes of + /t males are exposed to 'poison' coded by t loci, from which t sperm are protected, allowing t sperm an overwhelming fertilisation advantage in monogamous matings. This system is thought to result in poorly and normally motile sperm subpopulations within + /t sperm, leaving t sperm unharmed. Conversely, we found that the fastest quartile of sperm from + /t males swam more slowly, both forwards and along their travel path, and had reduced straightness and linearity, compared to the fastest quartile of + / + sperm. Moreover, sperm from + /t males had shorter tails and narrower heads than + / + sperm, and these morphological differences covaried with motility differences. Finally, + /t traits did not show evidence of bimodal distributions. We conclude that the t haplotype drive results in lasting damage to the motility of both + and t developing sperm, although previous studies indicate that + must be more harmed than t sperm. This damage to all sperm may explain the low success of + /t males in sperm competition with + / + males, seen in earlier studies. We propose that the harm the t causes to itself could be termed 'spiteful', which may also be common to other gamete-harming meiotic drive systems.
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Affiliation(s)
- Lennart Winkler
- Department of Evolutionary Biology, Bielefeld University, Konsequenz 45, 33615, Bielefeld, Germany
- Applied Zoology, TU Dresden, Zellescher Weg 20b, 01062, Dresden, Germany
| | - Anna K Lindholm
- Department of Evolutionary Biology and Environmental Studies, University of Zurich, Winterthurerstrasse 190, 8057, Zurich, Switzerland.
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20
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Carro MDLM, Grimson A, Cohen PE. Small RNAs and their protein partners in animal meiosis. Curr Top Dev Biol 2022; 151:245-279. [PMID: 36681472 DOI: 10.1016/bs.ctdb.2022.06.001] [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] [Indexed: 01/25/2023]
Abstract
Meiosis is characterized by highly regulated transitions in gene expression that require diverse mechanisms of gene regulation. For example, in male mammals, transcription undergoes a global shut-down in early prophase I of meiosis, followed by increasing transcriptional activity into pachynema. Later, as spermiogenesis proceeds, the histones bound to DNA are replaced with transition proteins, which are themselves replaced with protamines, resulting in a highly condensed nucleus with repressed transcriptional activity. In addition, two specialized gene silencing events take place during prophase I: meiotic silencing of unsynapsed chromatin (MSUC), and the sex chromatin specific mechanism, meiotic sex chromosome inactivation (MSCI). Notably, conserved roles for the RNA binding protein (RBP) machinery that functions with small non-coding RNAs have been described as participating in these meiosis-specific mechanisms, suggesting that RNA-mediated gene regulation is critical for fertility in many species. Here, we review roles of small RNAs and their associated RBPs in meiosis-related processes such as centromere function, silencing of unpaired chromatin and meiotic recombination. We will discuss the emerging evidence of non-canonical functions of these components in meiosis.
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Affiliation(s)
- María de Las Mercedes Carro
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, United States; Cornell Reproductive Sciences Center (CoRe), Cornell University, Ithaca, NY, United States
| | - Andrew Grimson
- Cornell Reproductive Sciences Center (CoRe), Cornell University, Ithaca, NY, United States; Department of Molecular Biology & Genetics, Cornell University, Ithaca, NY, United States.
| | - Paula E Cohen
- Department of Biomedical Sciences, Cornell University, Ithaca, NY, United States; Cornell Reproductive Sciences Center (CoRe), Cornell University, Ithaca, NY, United States.
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21
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Non-Mendelian segregation and transmission drive of B chromosomes. Chromosome Res 2022; 30:217-228. [DOI: 10.1007/s10577-022-09692-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2022] [Revised: 03/11/2022] [Accepted: 04/11/2022] [Indexed: 11/03/2022]
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22
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Abstract
Insects have evolved highly diverse genetic sex-determination mechanisms and a relatively balanced male to female sex ratio is generally expected. However, selection may shift the optimal sex ratio while meiotic drive and endosymbiont manipulation can result in sex ratio distortion (SRD). Recent advances in sex chromosome genomics and CRISPR/Cas9-mediated genome editing brought significant insights into the molecular regulators of sex determination in an increasing number of insects and provided new ways to engineer SRD. We review these advances and discuss both naturally occurring and engineered SRD in the context of the Anthropocene. We emphasize SRD-mediated biological control of insects to help improve One Health, sustain agriculture, and conserve endangered species.
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Affiliation(s)
- Austin Compton
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
| | - Zhijian Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA 24061, USA
- Fralin Life Sciences Institute, Virginia Tech, Blacksburg, VA 24061, USA
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23
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Alexandrov OS, Romanov DV, Divashuk MG, Razumova OV, Ulyanov DS, Karlov GI. Study and Physical Mapping of the Species-Specific Tandem Repeat CS-237 Linked with 45S Ribosomal DNA Intergenic Spacer in Cannabis sativa L. PLANTS (BASEL, SWITZERLAND) 2022; 11:1396. [PMID: 35684169 PMCID: PMC9183113 DOI: 10.3390/plants11111396] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/11/2022] [Revised: 05/11/2022] [Accepted: 05/20/2022] [Indexed: 06/15/2023]
Abstract
Hemp (Cannabis sativa L.) is a valuable crop and model plant for studying sex chromosomes. The scientific interest in the plant has led to its whole genome sequencing and the determination of its cytogenetic characteristics. A range of cytogenetic markers (subtelomeric repeat CS-1, 5S rDNA, and 45S rDNA) has been mapped onto hemp's chromosomes by fluorescent in situ hybridization (FISH). In this study, another cytogenetic marker (the tandem repeat CS-237, with a 237 bp monomer) was found, studied, and localized on chromosomes by FISH. The signal distribution and karyotyping revealed that the CS-237 probe was localized in chromosome 6 with one hybridization site and in chromosome 8 with two hybridization sites, one of which colocalizes with the 45S rDNA probe (with which a nucleolus organizer region, NOR, was detected). A BLAST analysis of the genomic data and PCR experiments showed that the modified CS-237 monomers (delCS-237, 208 bp in size) were present in the intergenic spacers (IGSs) of hemp 45S rDNA monomers. Such a feature was firstly observed in Cannabaceae species. However, IGS-linked DNA repeats were found in several plant species of other families (Fabaceae, Solanaceae, and Asteraceae). This phenomenon is discussed in this article. The example of CS-237 may be useful for further studying the phenomenon as well as for the physical mapping of hemp chromosomes.
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Affiliation(s)
| | - Dmitry V. Romanov
- All-Russia Research Institute of Agricultural Biotechnology, Timiryazevskaya 42, 127550 Moscow, Russia; (O.S.A.); (M.G.D.); (O.V.R.); (D.S.U.); (G.I.K.)
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24
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Neo-sex chromosome evolution shapes sex-dependent asymmetrical introgression barrier. Proc Natl Acad Sci U S A 2022; 119:e2119382119. [PMID: 35512091 PMCID: PMC9171612 DOI: 10.1073/pnas.2119382119] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
It is increasingly recognized that sex chromosomes are not only the battlegrounds between sexes but also the Great Walls fencing off introgression between diverging lineages. Here we dissect the multifaceted roles of sex chromosomes using experimental evolution, whole-genome resequencing, and theoretical modeling, taking advantage of hybrid populations between a Drosophila sister species pair in the early stage of speciation that have different sex chromosome systems. Our work sheds light onto the complex roles of neo-sex chromosome evolution in creating a sex-dependent asymmetrical introgression barrier at a species boundary, and we show how diverse population genetic forces act in concert to explain observed patterns of introgression across the genome. Sex chromosomes play a special role in the evolution of reproductive barriers between species. Here we describe conflicting roles of nascent sex chromosomes on patterns of introgression in an experimental hybrid swarm. Drosophila nasuta and Drosophila albomicans are recently diverged, fully fertile sister species that have different sex chromosome systems. The fusion between an autosome (Muller CD) with the ancestral X and Y gave rise to neo-sex chromosomes in D. albomicans, while Muller CD remains unfused in D. nasuta. We found that a large block containing overlapping inversions on the neo-sex chromosome stood out as the strongest barrier to introgression. Intriguingly, the neo-sex chromosome introgression barrier is asymmetrical and sex-dependent. Female hybrids showed significant D. albomicans–biased introgression on Muller CD (neo-X excess), while males showed heterosis with excessive (neo-X, D. nasuta Muller CD) genotypes. We used a population genetic model to dissect the interplay of sex chromosome drive, heterospecific pairing incompatibility between the neo-sex chromosomes and unfused Muller CD, neo-Y disadvantage, and neo-X advantage in generating the observed sex chromosome genotypes in females and males. We show that moderate neo-Y disadvantage and D. albomicans specific meiotic drive are required to observe female-specific D. albomicans–biased introgression in this system, together with pairing incompatibility and neo-X advantage. In conclusion, this hybrid swarm between a young species pair sheds light onto the multifaceted roles of neo-sex chromosomes in a sex-dependent asymmetrical introgression barrier at a species boundary.
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26
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Rapid evolutionary dynamics of an expanding family of meiotic drive factors and their hpRNA suppressors. Nat Ecol Evol 2021; 5:1613-1623. [PMID: 34862477 PMCID: PMC8665063 DOI: 10.1038/s41559-021-01592-z] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Accepted: 10/19/2021] [Indexed: 11/25/2022]
Abstract
Meiotic drivers are a class of selfish genetic elements whose existence is frequently hidden due to concomitant suppressor systems. Accordingly, we know little of their evolutionary breadth and molecular mechanisms. Here, we trace the evolution of the Dox meiotic drive system in Drosophila simulans, which affects male-female balance (sex-ratio). Dox emerged via stepwise mobilization and acquisition of multiple D. melanogaster gene segments including from protamine, which mediates compaction of sperm chromatin. Moreover, we reveal novel Dox homologs and massive amplification of Dox superfamily genes on X chromosomes of its closest sisters D. mauritiana and D. sechellia. Emergence of Dox loci is tightly associated with 359-class satellite repeats that flank de novo genomic copies. In concert, we find coordinated diversification of autosomal hairpin RNA-class siRNA loci that target subsets of Dox superfamily genes. Overall, we reveal fierce genetic arms races between meiotic drive factors and siRNA suppressors associated with recent speciation.
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