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Crepaldi C, Cabral-de-Mello DC, Parise-Maltempi PP. Comparative analysis of transposable elements dynamics in fish with different sex chromosome systems. Genome 2024. [PMID: 38739948 DOI: 10.1139/gen-2023-0134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Transposable elements (TEs) are widespread genomic components with substantial roles in genome evolution and sex chromosome differentiation. In this study, we compared the TE composition of three closely related fish with different sex chromosome systems: Megaleporinus elongatus (Z1Z1Z2Z2/Z1W1Z2W2), Megaleporinus macrocephalus (ZZ/ZW) (both with highly differentiated W sex chromosomes), and Leporinus friderici (without heteromorphic sex chromosomes). We created custom TE libraries for each species using clustering methods and manual annotation and prediction, and we predicted TE temporal dynamics through divergence-based analysis. The TE abundance ranged from 16% to 21% in the three mobilomes, with L. friderici having the lowest overall. Despite the recent amplification of TEs in all three species, we observed differing expansion activities, particularly between the two genera. Both Megaleporinus recently experienced high retrotransposon activity, with a reduction in DNA TEs, which could have implications in sex chromosome composition. In contrast, L. friderici showed the opposite pattern. Therefore, despite having similar TE compositions, Megaleporinus and Leporinus exhibit distinct TE histories that likely evolved after their separation, highlighting a rapid TE expansion over short evolutionary periods.
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Affiliation(s)
- Carolina Crepaldi
- Universidade Estadual Paulista (UNESP) "Júlio de Mesquita Filho", Instituto de Biociências, Departamento de Biologia Geral e Aplicada, Rio Claro, Brazil
| | - Diogo Cavalcanti Cabral-de-Mello
- Universidade Estadual Paulista (UNESP) "Júlio de Mesquita Filho", Instituto de Biociências, Departamento de Biologia Geral e Aplicada, Rio Claro, Brazil
| | - Patricia Pasquali Parise-Maltempi
- Universidade Estadual Paulista (UNESP) "Júlio de Mesquita Filho", Instituto de Biociências, Departamento de Biologia Geral e Aplicada, Rio Claro, Brazil
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2
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Tomar SS, Hua-Van A, Le Rouzic A. A population genetics theory for piRNA-regulated transposable elements. Theor Popul Biol 2023; 150:1-13. [PMID: 36863578 DOI: 10.1016/j.tpb.2023.02.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2022] [Revised: 02/16/2023] [Accepted: 02/21/2023] [Indexed: 03/04/2023]
Abstract
Transposable elements (TEs) are self-reproducing selfish DNA sequences that can invade the genome of virtually all living species. Population genetics models have shown that TE copy numbers generally reach a limit, either because the transposition rate decreases with the number of copies (transposition regulation) or because TE copies are deleterious, and thus purged by natural selection. Yet, recent empirical discoveries suggest that TE regulation may mostly rely on piRNAs, which require a specific mutational event (the insertion of a TE copy in a piRNA cluster) to be activated - the so-called TE regulation "trap model". We derived new population genetics models accounting for this trap mechanism, and showed that the resulting equilibria differ substantially from previous expectations based on a transposition-selection equilibrium. We proposed three sub-models, depending on whether or not genomic TE copies and piRNA cluster TE copies are selectively neutral or deleterious, and we provide analytical expressions for maximum and equilibrium copy numbers, as well as cluster frequencies for all of them. In the full neutral model, the equilibrium is achieved when transposition is completely silenced, and this equilibrium does not depend on the transposition rate. When genomic TE copies are deleterious but not cluster TE copies, no long-term equilibrium is possible, and active TEs are eventually eliminated after an active incomplete invasion stage. When all TE copies are deleterious, a transposition-selection equilibrium exists, but the invasion dynamics is not monotonic, and the copy number peaks before decreasing. Mathematical predictions were in good agreement with numerical simulations, except when genetic drift and/or linkage disequilibrium dominates. Overall, the trap-model dynamics appeared to be substantially more stochastic and less repeatable than traditional regulation models.
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Affiliation(s)
- Siddharth S Tomar
- Université Paris-Saclay, CNRS, IRD, UMR EGCE, 12 Route 128, Gif-sur-Yvette, 91190, France.
| | - Aurélie Hua-Van
- Université Paris-Saclay, CNRS, IRD, UMR EGCE, 12 Route 128, Gif-sur-Yvette, 91190, France.
| | - Arnaud Le Rouzic
- Université Paris-Saclay, CNRS, IRD, UMR EGCE, 12 Route 128, Gif-sur-Yvette, 91190, France.
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3
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Liu X, Zhang Y, Pu Y, Ma Y, Jiang L. Whole-genome identification of transposable elements reveals the equine repetitive element insertion polymorphism in Chinese horses. Anim Genet 2023; 54:144-154. [PMID: 36464985 DOI: 10.1111/age.13277] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2022] [Revised: 10/29/2022] [Accepted: 11/14/2022] [Indexed: 12/12/2022]
Abstract
Transposable elements (TEs) are diverse, abundant, and complicated in genomes. They not only can drive the genome evolution process but can also act as special resources for adaptation. However, little is known about the evolutionary processes that shaped horses. In this work, 126 horse assemblages involved in most horse breeds in China were used to investigate the patterns of TE variation for the first time. By using RepeatMasker and melt software, we found that the horse-specific short interspersed repetitive elements family, equine repetitive elements (ERE1), exhibited polymorphisms in horse genomes. Phylogenetic analysis based on these ERE1 loci (minor allele frequency ≥0.05) revealed three major horse groups, namely, those in northern China, southern China, and Qinghai-Tibetan, which mirrors the result determined by SNPs to some extent. The present ERE1 family emerged ~0.26 to 1.77 Mya ago, with an activity peak at ~0.49 Mya, which matches the early stage of the horse lineage and decreases after the divergence of Equus caballus and Equus ferus przewalskii. To detect the functional ERE1(s) associated with adaptation, locus-specific branch length, genome-wide association study, and absolute allele frequency difference analyses were conducted and resulted in two common protein-coding genes annotated by candidate ERE1s. They were clustered into the vascular smooth muscle contraction (p = 0.01, EDNRA) and apelin signalling pathways (p = 0.02, NRF1). Notably, ERE1 insertion into the EDNRA gene showed a higher association with adaptation among southern China horses and other horses in 15 populations and 451 individuals (p = 4.55 e-8). Our results provide a comprehensive understanding of TE variations to analyse the phylogenetic relationships and traits relevant to adaptive evolution in horses.
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Affiliation(s)
- Xuexue Liu
- National Germplasm Centre of Domestic Animal Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.,Centre d'Anthropobiologie et de Génomique de Toulouse, Université Paul Sabatier, Toulouse, France
| | - Yanli Zhang
- National Germplasm Centre of Domestic Animal Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.,CAAS-ILRI Joint Laboratory on Livestock and Forage Genetic Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Yabin Pu
- National Germplasm Centre of Domestic Animal Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.,CAAS-ILRI Joint Laboratory on Livestock and Forage Genetic Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Yuehui Ma
- National Germplasm Centre of Domestic Animal Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.,CAAS-ILRI Joint Laboratory on Livestock and Forage Genetic Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
| | - Lin Jiang
- National Germplasm Centre of Domestic Animal Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China.,CAAS-ILRI Joint Laboratory on Livestock and Forage Genetic Resources, Institute of Animal Science, Chinese Academy of Agricultural Sciences (CAAS), Beijing, China
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4
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Ní Leathlobhair M, Lenski RE. Population genetics of clonally transmissible cancers. Nat Ecol Evol 2022; 6:1077-1089. [PMID: 35879542 DOI: 10.1038/s41559-022-01790-3] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2021] [Accepted: 05/12/2022] [Indexed: 11/08/2022]
Abstract
Populations of cancer cells are subject to the same core evolutionary processes as asexually reproducing, unicellular organisms. Transmissible cancers are particularly striking examples of these processes. These unusual cancers are clonal lineages that can spread through populations via physical transfer of living cancer cells from one host individual to another, and they have achieved long-term success in the colonization of at least eight different host species. Population genetic theory provides a useful framework for understanding the shift from a multicellular sexual animal into a unicellular asexual clone and its long-term effects on the genomes of these cancers. In this Review, we consider recent findings from transmissible cancer research with the goals of developing an evolutionarily informed perspective on transmissible cancers, examining possible implications for their long-term fate and identifying areas for future research on these exceptional lineages.
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Affiliation(s)
- Máire Ní Leathlobhair
- Big Data Institute, Li Ka Shing Centre for Health Information and Discovery, University of Oxford, Oxford, UK.
- Ludwig Institute for Cancer Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK.
- Department of Microbiology, Moyne Institute of Preventive Medicine, School of Genetics and Microbiology, Trinity College Dublin, Dublin, Ireland.
| | - Richard E Lenski
- Department of Microbiology and Molecular Genetics, Michigan State University, East Lansing, MI, USA
- Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, USA
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5
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Bacterial N4-methylcytosine as an epigenetic mark in eukaryotic DNA. Nat Commun 2022; 13:1072. [PMID: 35228526 PMCID: PMC8885841 DOI: 10.1038/s41467-022-28471-w] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2021] [Accepted: 01/21/2022] [Indexed: 01/04/2023] Open
Abstract
DNA modifications are used to regulate gene expression and defend against invading genetic elements. In eukaryotes, modifications predominantly involve C5-methylcytosine (5mC) and occasionally N6-methyladenine (6mA), while bacteria frequently use N4-methylcytosine (4mC) in addition to 5mC and 6mA. Here we report that 4mC can serve as an epigenetic mark in eukaryotes. Bdelloid rotifers, tiny freshwater invertebrates with transposon-poor genomes rich in foreign genes, lack canonical eukaryotic C5-methyltransferases for 5mC addition, but encode an amino-methyltransferase, N4CMT, captured from bacteria >60 Mya. N4CMT deposits 4mC at active transposons and certain tandem repeats, and fusion to a chromodomain shapes its “histone-read-DNA-write” architecture recognizing silent chromatin marks. Furthermore, amplification of SETDB1 H3K9me3 histone methyltransferases yields variants preferentially binding 4mC-DNA, suggesting “DNA-read-histone-write” partnership to maintain chromatin-based silencing. Our results show how non-native DNA methyl groups can reshape epigenetic systems to silence transposons and demonstrate the potential of horizontal gene transfer to drive regulatory innovation in eukaryotes. Eukaryotic DNA can be methylated as 5-methylcytosine and N6-methyladenine, but whether other forms of DNA methylation occur has been controversial. Here the authors show that a bacterial DNA methyltransferase was acquired >60 Mya in bdelloid rotifers that catalyzes N4-methylcytosine addition and is involved in suppression of transposon proliferation.
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van Dijk B, Bertels F, Stolk L, Takeuchi N, Rainey PB. Transposable elements promote the evolution of genome streamlining. Philos Trans R Soc Lond B Biol Sci 2022; 377:20200477. [PMID: 34839699 PMCID: PMC8628081 DOI: 10.1098/rstb.2020.0477] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2021] [Accepted: 08/30/2021] [Indexed: 12/25/2022] Open
Abstract
Eukaryotes and prokaryotes have distinct genome architectures, with marked differences in genome size, the ratio of coding/non-coding DNA, and the abundance of transposable elements (TEs). As TEs replicate independently of their hosts, the proliferation of TEs is thought to have driven genome expansion in eukaryotes. However, prokaryotes also have TEs in intergenic spaces, so why do prokaryotes have small, streamlined genomes? Using an in silico model describing the genomes of single-celled asexual organisms that coevolve with TEs, we show that TEs acquired from the environment by horizontal gene transfer can promote the evolution of genome streamlining. The process depends on local interactions and is underpinned by rock-paper-scissors dynamics in which populations of cells with streamlined genomes beat TEs, which beat non-streamlined genomes, which beat streamlined genomes, in continuous and repeating cycles. Streamlining is maladaptive to individual cells, but improves lineage viability by hindering the proliferation of TEs. Streamlining does not evolve in sexually reproducing populations because recombination partially frees TEs from the deleterious effects they cause. This article is part of the theme issue 'The secret lives of microbial mobile genetic elements'.
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Affiliation(s)
- Bram van Dijk
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Frederic Bertels
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
| | - Lianne Stolk
- Theoretical Biology, Department of Biology, Utrecht University, The Netherlands
| | - Nobuto Takeuchi
- School of Biological Sciences, University of Auckland, Auckland, New Zealand
| | - Paul B. Rainey
- Department of Microbial Population Biology, Max Planck Institute for Evolutionary Biology, Plön, Germany
- Laboratory of Biophysics and Evolution, CBI, ESPCI Paris, Université PSL, CNRS, Paris, France
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7
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Underwood CJ, Vijverberg K, Rigola D, Okamoto S, Oplaat C, Camp RHMOD, Radoeva T, Schauer SE, Fierens J, Jansen K, Mansveld S, Busscher M, Xiong W, Datema E, Nijbroek K, Blom EJ, Bicknell R, Catanach A, Erasmuson S, Winefield C, van Tunen AJ, Prins M, Schranz ME, van Dijk PJ. A PARTHENOGENESIS allele from apomictic dandelion can induce egg cell division without fertilization in lettuce. Nat Genet 2022; 54:84-93. [PMID: 34992267 DOI: 10.1038/s41588-021-00984-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Accepted: 11/03/2021] [Indexed: 01/21/2023]
Abstract
Apomixis, the clonal formation of seeds, is a rare yet widely distributed trait in flowering plants. We have isolated the PARTHENOGENESIS (PAR) gene from apomictic dandelion that triggers embryo development in unfertilized egg cells. PAR encodes a K2-2 zinc finger, EAR-domain protein. Unlike the recessive sexual alleles, the dominant PAR allele is expressed in egg cells and has a miniature inverted-repeat transposable element (MITE) transposon insertion in the promoter. The MITE-containing promoter can invoke a homologous gene from sexual lettuce to complement dandelion LOSS OF PARTHENOGENESIS mutants. A similar MITE is also present in the promoter of the PAR gene in apomictic forms of hawkweed, suggesting a case of parallel evolution. Heterologous expression of dandelion PAR in lettuce egg cells induced haploid embryo-like structures in the absence of fertilization. Sexual PAR alleles are expressed in pollen, suggesting that the gene product releases a block on embryogenesis after fertilization in sexual species while in apomictic species PAR expression triggers embryogenesis in the absence of fertilization.
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Affiliation(s)
- Charles J Underwood
- Keygene N.V., Wageningen, the Netherlands
- Department of Chromosome Biology, Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Kitty Vijverberg
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
- Naturalis Biodiversity Center, Radboud University, Nijmegen, the Netherlands
| | | | - Shunsuke Okamoto
- Keygene N.V., Wageningen, the Netherlands
- Takii & Co. Ltd, Plant Breeding and Experiment Station, Konan Shiga, Japan
| | - Carla Oplaat
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
- National Reference Centre of Plant Health, National Plant Protection Organization, Wageningen, the Netherlands
| | | | | | | | | | - Kim Jansen
- Keygene N.V., Wageningen, the Netherlands
| | | | - Marco Busscher
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
| | - Wei Xiong
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands
| | | | | | | | - Ross Bicknell
- New Zealand Institute for Plant & Food Research, Lincoln, New Zealand
| | - Andrew Catanach
- New Zealand Institute for Plant & Food Research, Lincoln, New Zealand
| | - Sylvia Erasmuson
- New Zealand Institute for Plant & Food Research, Lincoln, New Zealand
| | | | | | | | - M Eric Schranz
- Biosystematics Group, Wageningen University, Wageningen, the Netherlands.
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8
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Laine VN, Sackton T, Meselson M. Genomic Signature of Sexual Reproduction in the Bdelloid Rotifer Macrotrachella quadricornifera. Genetics 2021; 220:6458333. [PMID: 34888647 DOI: 10.1093/genetics/iyab221] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Accepted: 11/10/2021] [Indexed: 11/13/2022] Open
Abstract
Bdelloid rotifers, common freshwater invertebrates of ancient origin and worldwide distribution have long been thought to be entirely asexual, being the principal exception to the view that in eukaryotes the loss of sex leads to early extinction. That bdelloids are facultatively sexual is shown by a study of allele sharing within a group of closely related bdelloids of the species Macrotrachella quadricornifera, supporting the view that sexual reproduction is essential for long-term success in all eukaryotes.
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Affiliation(s)
- Veronika N Laine
- Department of Animal Ecology, Finnish Museum of Natural History, University of Helsinki, Helsinki 00100, Finland
| | - Timothy Sackton
- Informatics Group, Faculty of Arts and Sciences, Harvard University, Cambridge, MA 02138; USA
| | - Matthew Meselson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA 02138, USA
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9
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Simion P, Narayan J, Houtain A, Derzelle A, Baudry L, Nicolas E, Arora R, Cariou M, Cruaud C, Gaudray FR, Gilbert C, Guiglielmoni N, Hespeels B, Kozlowski DKL, Labadie K, Limasset A, Llirós M, Marbouty M, Terwagne M, Virgo J, Cordaux R, Danchin EGJ, Hallet B, Koszul R, Lenormand T, Flot JF, Van Doninck K. Chromosome-level genome assembly reveals homologous chromosomes and recombination in asexual rotifer Adineta vaga. SCIENCE ADVANCES 2021; 7:eabg4216. [PMID: 34613768 PMCID: PMC8494291 DOI: 10.1126/sciadv.abg4216] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Bdelloid rotifers are notorious as a speciose ancient clade comprising only asexual lineages. Thanks to their ability to repair highly fragmented DNA, most bdelloid species also withstand complete desiccation and ionizing radiation. Producing a well-assembled reference genome is a critical step to developing an understanding of the effects of long-term asexuality and DNA breakage on genome evolution. To this end, we present the first high-quality chromosome-level genome assemblies for the bdelloid Adineta vaga, composed of six pairs of homologous (diploid) chromosomes with a footprint of paleotetraploidy. The observed large-scale losses of heterozygosity are signatures of recombination between homologous chromosomes, either during mitotic DNA double-strand break repair or when resolving programmed DNA breaks during a modified meiosis. Dynamic subtelomeric regions harbor more structural diversity (e.g., chromosome rearrangements, transposable elements, and haplotypic divergence). Our results trigger the reappraisal of potential meiotic processes in bdelloid rotifers and help unravel the factors underlying their long-term asexual evolutionary success.
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Affiliation(s)
- Paul Simion
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
- Corresponding author. (K.V.D.); (J.-F.F.); (P.S.)
| | - Jitendra Narayan
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
| | - Antoine Houtain
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
| | - Alessandro Derzelle
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
| | - Lyam Baudry
- Institut Pasteur, Unité Régulation Spatiale des Génomes, UMR 3525, CNRS, Paris F-75015, France
- Collège Doctoral, Sorbonne Université, F-75005 Paris, France
| | - Emilien Nicolas
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
- Molecular Biology and Evolution, Université libre de Bruxelles (ULB), Brussels 1050, Belgium
| | - Rohan Arora
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
- Molecular Biology and Evolution, Université libre de Bruxelles (ULB), Brussels 1050, Belgium
| | - Marie Cariou
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
- CIRI, Centre International de Recherche en Infectiologie, Univ Lyon, Inserm, U1111, Université Claude Bernard Lyon 1, CNRS, UMR5308, ENS de Lyon, F-69007 Lyon, France
| | - Corinne Cruaud
- Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | | | - Clément Gilbert
- Évolution, Génomes, Comportement et Écologie, Université Paris-Saclay, CNRS, IRD, UMR, 91198 Gif-sur-Yvette, France
| | - Nadège Guiglielmoni
- Evolutionary Biology and Ecology, Université libre de Bruxelles (ULB), Brussels 1050, Belgium
| | - Boris Hespeels
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
| | - Djampa K. L. Kozlowski
- INRAE, Université Côte-d’Azur, CNRS, Institut Sophia Agrobiotech, Sophia Antipolis 06903, France
| | - Karine Labadie
- Genoscope, Institut François Jacob, CEA, CNRS, Univ Evry, Université Paris-Saclay, 91057 Evry, France
| | - Antoine Limasset
- Université de Lille, CNRS, UMR 9189 - CRIStAL, 59655 Villeneuve-d’Ascq, France
| | - Marc Llirós
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
- Institut d’Investigació Biomédica de Girona, Malalties Digestives i Microbiota, 17190 Salt, Spain
| | - Martial Marbouty
- Institut Pasteur, Unité Régulation Spatiale des Génomes, UMR 3525, CNRS, Paris F-75015, France
| | - Matthieu Terwagne
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
| | - Julie Virgo
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
| | - Richard Cordaux
- Ecologie et Biologie des interactions, Université de Poitiers, UMR CNRS 7267, 5 rue Albert Turpain, 86073 Poitiers, France
| | - Etienne G. J. Danchin
- INRAE, Université Côte-d’Azur, CNRS, Institut Sophia Agrobiotech, Sophia Antipolis 06903, France
| | - Bernard Hallet
- LIBST, Université Catholique de Louvain (UCLouvain), Croix du Sud 4/5, Louvain-la-Neuve 1348, Belgium
| | - Romain Koszul
- Institut Pasteur, Unité Régulation Spatiale des Génomes, UMR 3525, CNRS, Paris F-75015, France
| | - Thomas Lenormand
- CEFE, Univ Montpellier, CNRS, Univ Paul Valéry Montpellier 3, EPHE, IRD, Montpellier, France
| | - Jean-Francois Flot
- Evolutionary Biology and Ecology, Université libre de Bruxelles (ULB), Brussels 1050, Belgium
- Interuniversity Institute of Bioinformatics in Brussels - (IB), Brussels 1050, Belgium
- Corresponding author. (K.V.D.); (J.-F.F.); (P.S.)
| | - Karine Van Doninck
- Research Unit in Environmental and Evolutionary Biology, Université de Namur, Namur 5000, Belgium
- Molecular Biology and Evolution, Université libre de Bruxelles (ULB), Brussels 1050, Belgium
- Corresponding author. (K.V.D.); (J.-F.F.); (P.S.)
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10
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A Survey of Transposon Landscapes in the Putative Ancient Asexual Ostracod Darwinula stevensoni. Genes (Basel) 2021; 12:genes12030401. [PMID: 33799706 PMCID: PMC7998251 DOI: 10.3390/genes12030401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/02/2021] [Accepted: 03/06/2021] [Indexed: 11/17/2022] Open
Abstract
How asexual reproduction shapes transposable element (TE) content and diversity in eukaryotic genomes remains debated. We performed an initial survey of TE load and diversity in the putative ancient asexual ostracod Darwinula stevensoni. We examined long contiguous stretches of DNA in clones from a genomic fosmid library, totaling about 2.5 Mb, and supplemented these data with results on TE abundance and diversity from an Illumina draft genome. In contrast to other TE studies in putatively ancient asexuals, which revealed relatively low TE content, we found that at least 19% of the fosmid dataset and 26% of the genome assembly corresponded to known transposons. We observed a high diversity of transposon families, including LINE, gypsy, PLE, mariner/Tc, hAT, CMC, Sola2, Ginger, Merlin, Harbinger, MITEs and helitrons, with the prevalence of DNA transposons. The predominantly low levels of sequence diversity indicate that many TEs are or have recently been active. In the fosmid data, no correlation was found between telomeric repeats and non-LTR retrotransposons, which are present near telomeres in other taxa. Most TEs in the fosmid data were located outside of introns and almost none were found in exons. We also report an N-terminal Myb/SANT-like DNA-binding domain in site-specific R4/Dong non-LTR retrotransposons. Although initial results on transposable loads need to be verified with high quality draft genomes, this study provides important first insights into TE dynamics in putative ancient asexual ostracods.
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11
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Flores-Ferrer A, Nguyen A, Glémin S, Deragon JM, Panaud O, Gourbière S. The ecology of the genome and the dynamics of the biological dark matter. J Theor Biol 2021; 518:110641. [PMID: 33640450 DOI: 10.1016/j.jtbi.2021.110641] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2020] [Revised: 12/28/2020] [Accepted: 02/11/2021] [Indexed: 11/29/2022]
Abstract
Transposable elements (TEs) are essential components of the eukaryotic genomes. While mostly deleterious, evidence is mounting that TEs provide the host with beneficial adaptations. How 'selfish' or 'parasitic' DNA persists until it helps species evolution is emerging as a major evolutionary puzzle, especially in asexual taxa where the lack of sex strongly impede the spread of TEs. Since occasional but unchecked TE proliferations would ultimately drive host lineages toward extinction, asexual genomes are typically predicted to be free of TEs, which contrasts with their persistence in asexual taxa. We designed innovative 'Eco-genomic' models that account for both host demography and within-host molecular mechanisms of transposition and silencing to analyze their impact on TE dynamics in asexual genome populations. We unraveled that the spread of TEs can be limited to a stable level by density-dependent purifying selection when TE copies are over-dispersed among lineages and the host demographic turn-over is fast. We also showed that TE silencing can protect host populations in two ways; by preventing TEs with weak effects to accumulate or by favoring the elimination of TEs with large effects. Our predictions may explain TE persistence in known asexual taxa that typically show fast demography and where TE copy number variation between lineages is expected. Such TE persistence in asexual taxa potentially has important implications for their evolvability and the preservation of sexual reproduction.
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Affiliation(s)
- Alheli Flores-Ferrer
- UMR5096 'Laboratoire Génome et Développement des Plantes', Université de Perpignan Via Domitia, Perpignan, France.
| | - Anne Nguyen
- UMR5096 'Laboratoire Génome et Développement des Plantes', Université de Perpignan Via Domitia, Perpignan, France.
| | - Sylvain Glémin
- UMR 6553 'Ecosystèmes, Biodiversité, Evolution', Université de Rennes 1, Rennes, France.
| | - Jean-Marc Deragon
- UMR5096 'Laboratoire Génome et Développement des Plantes', Université de Perpignan Via Domitia, Perpignan, France.
| | - Olivier Panaud
- UMR5096 'Laboratoire Génome et Développement des Plantes', Université de Perpignan Via Domitia, Perpignan, France.
| | - Sébastien Gourbière
- UMR5096 'Laboratoire Génome et Développement des Plantes', Université de Perpignan Via Domitia, Perpignan, France; Centre for the Study of Evolution, School of Life Sciences, University of Sussex, Brighton BN1 9QG, United Kingdom.
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12
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Nowell RW, Wilson CG, Almeida P, Schiffer PH, Fontaneto D, Becks L, Rodriguez F, Arkhipova IR, Barraclough TG. Evolutionary dynamics of transposable elements in bdelloid rotifers. eLife 2021; 10:e63194. [PMID: 33543711 PMCID: PMC7943196 DOI: 10.7554/elife.63194] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2020] [Accepted: 02/04/2021] [Indexed: 12/17/2022] Open
Abstract
Transposable elements (TEs) are selfish genomic parasites whose ability to spread autonomously is facilitated by sexual reproduction in their hosts. If hosts become obligately asexual, TE frequencies and dynamics are predicted to change dramatically, but the long-term outcome is unclear. Here, we test current theory using whole-genome sequence data from eight species of bdelloid rotifers, a class of invertebrates in which males are thus far unknown. Contrary to expectations, we find a variety of active TEs in bdelloid genomes, at an overall frequency within the range seen in sexual species. We find no evidence that TEs are spread by cryptic recombination or restrained by unusual DNA repair mechanisms. Instead, we find that that TE content evolves relatively slowly in bdelloids and that gene families involved in RNAi-mediated TE suppression have undergone significant expansion, which might mitigate the deleterious effects of active TEs and compensate for the consequences of long-term asexuality.
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Affiliation(s)
- Reuben W Nowell
- Department of Zoology, University of OxfordOxfordUnited Kingdom
- Department of Life Sciences, Imperial College London, Silwood Park CampusAscot, BerkshireUnited Kingdom
| | - Christopher G Wilson
- Department of Zoology, University of OxfordOxfordUnited Kingdom
- Department of Life Sciences, Imperial College London, Silwood Park CampusAscot, BerkshireUnited Kingdom
| | - Pedro Almeida
- Department of Life Sciences, Imperial College London, Silwood Park CampusAscot, BerkshireUnited Kingdom
- Division of Biosciences, University College LondonLondonUnited Kingdom
| | - Philipp H Schiffer
- Institute of Zoology, Section Developmental Biology, University of Cologne, KölnWormlabGermany
| | - Diego Fontaneto
- National Research Council of Italy, Water Research InstituteVerbania PallanzaItaly
| | - Lutz Becks
- Community Dynamics Group, Department of Evolutionary Ecology, Max Planck Institute for Evolutionary BiologyPlönGermany
- Aquatic Ecology and Evolution, University of KonstanzKonstanzGermany
| | - Fernando Rodriguez
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological LaboratoryWoods Hole, MAUnited States
| | - Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological LaboratoryWoods Hole, MAUnited States
| | - Timothy G Barraclough
- Department of Zoology, University of OxfordOxfordUnited Kingdom
- Department of Life Sciences, Imperial College London, Silwood Park CampusAscot, BerkshireUnited Kingdom
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13
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Laureau R, Dyatel A, Dursuk G, Brown S, Adeoye H, Yue JX, De Chiara M, Harris A, Ünal E, Liti G, Adams IR, Berchowitz LE. Meiotic Cells Counteract Programmed Retrotransposon Activation via RNA-Binding Translational Repressor Assemblies. Dev Cell 2020; 56:22-35.e7. [PMID: 33278343 DOI: 10.1016/j.devcel.2020.11.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 06/25/2020] [Accepted: 11/06/2020] [Indexed: 12/14/2022]
Abstract
Retrotransposon proliferation poses a threat to germline integrity. While retrotransposons must be activated in developing germ cells in order to survive and propagate, how they are selectively activated in the context of meiosis is unclear. We demonstrate that the transcriptional activation of Ty3/Gypsy retrotransposons and host defense are controlled by master meiotic regulators. We show that budding yeast Ty3/Gypsy co-opts binding sites of the essential meiotic transcription factor Ndt80 upstream of the integration site, thereby tightly linking its transcriptional activation to meiotic progression. We also elucidate how yeast cells thwart Ty3/Gypsy proliferation by blocking translation of the retrotransposon mRNA using amyloid-like assemblies of the RNA-binding protein Rim4. In mammals, several inactive Ty3/Gypsy elements are undergoing domestication. We show that mammals utilize equivalent master meiotic regulators (Stra8, Mybl1, Dazl) to regulate Ty3/Gypsy-derived genes in developing gametes. Our findings inform how genes that are evolving from retrotransposons can build upon existing regulatory networks during domestication.
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Affiliation(s)
- Raphaelle Laureau
- Department of Genetics and Development, Hammer Health Sciences Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Annie Dyatel
- Department of Genetics and Development, Hammer Health Sciences Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Gizem Dursuk
- Department of Genetics and Development, Hammer Health Sciences Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Samantha Brown
- Department of Genetics and Development, Hammer Health Sciences Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Hannah Adeoye
- Department of Genetics and Development, Hammer Health Sciences Center, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jia-Xing Yue
- Université Côte d'Azur, CNRS, INSERM, IRCAN, Nice 06107, France
| | | | - Anthony Harris
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Elçin Ünal
- Department of Molecular and Cell Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Gianni Liti
- Université Côte d'Azur, CNRS, INSERM, IRCAN, Nice 06107, France
| | - Ian R Adams
- MRC Human Genetics Unit, MRC Institute of Genetics and Molecular Medicine, University of Edinburgh, Edinburgh EH4 2XU, UK
| | - Luke E Berchowitz
- Department of Genetics and Development, Hammer Health Sciences Center, Columbia University Irving Medical Center, New York, NY 10032, USA.
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14
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Serrato-Capuchina A, Wang J, Earley E, Peede D, Isbell K, Matute DR. Paternally Inherited P-Element Copy Number Affects the Magnitude of Hybrid Dysgenesis in Drosophila simulans and D. melanogaster. Genome Biol Evol 2020; 12:808-826. [PMID: 32339225 PMCID: PMC7313671 DOI: 10.1093/gbe/evaa084] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/20/2020] [Indexed: 12/16/2022] Open
Abstract
Transposable elements (TEs) are repetitive regions of DNA that are able to self-replicate and reinsert themselves throughout host genomes. Since the discovery of TEs, a prevalent question has been whether increasing TE copy number has an effect on the fitness of their hosts. P-elements (PEs) in Drosophila are a well-studied TE that has strong phenotypic effects. When a female without PEs (M) is crossed to a male with them (P), the resulting females are often sterile, a phenomenon called hybrid dysgenesis (HD). Here, we used short- and long-read sequencing to infer the number of PEs in the genomes of dozens of isofemale lines from two Drosophila species and measured whether the magnitude of HD was correlated with the number of PEs in the paternal genome. Consistent with previous reports, we find evidence for a positive correlation between the paternal PE copy number and the magnitude of HD in progeny from ♀M × ♂ P crosses for both species. Other crosses are not affected by the number of PE copies. We also find that the correlation between the strength of HD and PE copy number differs between species, which suggests that there are genetic differences that might make some genomes more resilient to the potentially deleterious effects of TEs. Our results suggest that PE copy number interacts with other factors in the genome and the environment to cause HD and that the importance of these interactions is species specific.
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Affiliation(s)
| | - Jeremy Wang
- Genetics Department, University of North Carolina, Chapel Hill
| | - Eric Earley
- Genomics in Public Health and Medicine RTI International, Research Triangle Park, North Carolina
| | - David Peede
- Biology Department, University of North Carolina, Chapel Hill
| | - Kristin Isbell
- Biology Department, University of North Carolina, Chapel Hill
| | - Daniel R Matute
- Biology Department, University of North Carolina, Chapel Hill
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15
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Kremer SC, Linquist S, Saylor B, Elliott TA, Gregory TR, Cottenie K. Transposable element persistence via potential genome-level ecosystem engineering. BMC Genomics 2020; 21:367. [PMID: 32429843 PMCID: PMC7236351 DOI: 10.1186/s12864-020-6763-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/20/2019] [Accepted: 04/30/2020] [Indexed: 12/15/2022] Open
Abstract
BACKGROUND The nuclear genomes of eukaryotes vary enormously in size, with much of this variability attributable to differential accumulation of transposable elements (TEs). To date, the precise evolutionary and ecological conditions influencing TE accumulation remain poorly understood. Most previous attempts to identify these conditions have focused on evolutionary processes occurring at the host organism level, whereas we explore a TE ecology explanation. RESULTS As an alternative (or additional) hypothesis, we propose that ecological mechanisms occurring within the host cell may contribute to patterns of TE accumulation. To test this idea, we conducted a series of experiments using a simulated asexual TE/host system. Each experiment tracked the accumulation rate for a given type of TE within a particular host genome. TEs in this system had a net deleterious effect on host fitness, which did not change over the course of experiments. As one might expect, in the majority of experiments TEs were either purged from the genome or drove the host population to extinction. However, in an intriguing handful of cases, TEs co-existed with hosts and accumulated to very large numbers. This tended to occur when TEs achieved a stable density relative to non-TE sequences in the genome (as opposed to reaching any particular absolute number). In our model, the only way to maintain a stable density was for TEs to generate new, inactive copies at a rate that balanced with the production of active (replicating) copies. CONCLUSIONS From a TE ecology perspective, we suggest this could be interpreted as a case of ecosystem engineering within the genome, where TEs persist by creating their own "habitat".
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Affiliation(s)
- Stefan C Kremer
- School of Computer Science, University of Guelph, Guelph, ON, N1G 2W1, Canada.
| | - Stefan Linquist
- Department of Philosophy, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Brent Saylor
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Tyler A Elliott
- Centre for Biodiversity Genomics, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - T Ryan Gregory
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
| | - Karl Cottenie
- Department of Integrative Biology, University of Guelph, Guelph, ON, N1G 2W1, Canada
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16
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Bast J, Jaron KS, Schuseil D, Roze D, Schwander T. Asexual reproduction reduces transposable element load in experimental yeast populations. eLife 2019; 8:48548. [PMID: 31486772 PMCID: PMC6783261 DOI: 10.7554/elife.48548] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Accepted: 09/04/2019] [Indexed: 01/04/2023] Open
Abstract
Theory predicts that sexual reproduction can either facilitate or restrain transposable element (TE) accumulation by providing TEs with a means of spreading to all individuals in a population, versus facilitating TE load reduction via purifying selection. By quantifying genomic TE loads over time in experimental sexual and asexual Saccharomyces cerevisiae populations, we provide direct evidence that TE loads decrease rapidly under asexual reproduction. We show, using simulations, that this reduction may occur via evolution of TE activity, most likely via increased excision rates. Thus, sex is a major driver of genomic TE loads and at the root of the success of TEs. The genetic information of most living organisms contains parasitic invaders known as transposable elements. These genetic sequences multiply by copying and pasting themselves through the genome, but this process can disrupt the activity of important genes and put the organism at risk. How transposable elements proliferate in a population depends on the way organisms reproduce. If they simply clone themselves asexually, the selfish elements cannot spread between the different clones. If the organisms mate together their respective transposable elements get mixed, which helps the sequences to spread more easily and to potentially become more virulent. However, sexual reproduction also comes with mechanisms that keep transposable elements in check. Bast, Jaron et al. took advantage of the fact that yeasts can reproduce with or without mating to explore whether sexual or asexual organisms are better at controlling the spread of transposable elements. The number of copies of transposable elements in the genomes of yeast grown sexually or asexually was assessed. The results showed that sexual populations kept constant numbers of selfish elements, while asexual organisms lost these genomic parasites over time. Simulations then revealed that this difference emerged because a defense gene that helps to delete transposable elements was spreading more quickly in the asexual group. The work by Bast, Jaron et al. therefore suggests that sex is responsible for the evolutionary success of transposable elements, while asexual populations can discard these sequences over time. Sex therefore helps genetic parasites, somewhat similar to sexually transmitted diseases, to spread between individuals and remain virulent.
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Affiliation(s)
- Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Kamil S Jaron
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland.,Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Donovan Schuseil
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Denis Roze
- UMI3614 Evolutionary Biology and Ecology of Alga, Centre National de la Recherche Scientifique (CNRS), Roscoff, France.,Station Biologique de Roscoff, Sorbonne Université, Roscoff, France
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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17
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Schemberger MO, Nascimento VD, Coan R, Ramos É, Nogaroto V, Ziemniczak K, Valente GT, Moreira-Filho O, Martins C, Vicari MR. DNA transposon invasion and microsatellite accumulation guide W chromosome differentiation in a Neotropical fish genome. Chromosoma 2019; 128:547-560. [DOI: 10.1007/s00412-019-00721-9] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Revised: 05/25/2019] [Accepted: 08/06/2019] [Indexed: 11/28/2022]
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18
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Abstract
Among the multitude of papers published yearly in scientific journals, precious few publications may be worth looking back in half a century to appreciate the significance of the discoveries that would later become common knowledge and get a chance to shape a field or several adjacent fields. Here, Kimura's fundamental concept of neutral mutation-random drift, which was published 50 years ago, is re-examined in light of its pervasive influence on comparative genomics and, more specifically, on the contribution of transposable elements to eukaryotic genome evolution.
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Affiliation(s)
- Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA
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19
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Abstract
A major current molecular evolution challenge is to link comparative genomic patterns to species' biology and ecology. Breeding systems are pivotal because they affect many population genetic processes and thus genome evolution. We review theoretical predictions and empirical evidence about molecular evolutionary processes under three distinct breeding systems-outcrossing, selfing, and asexuality. Breeding systems may have a profound impact on genome evolution, including molecular evolutionary rates, base composition, genomic conflict, and possibly genome size. We present and discuss the similarities and differences between the effects of selfing and clonality. In reverse, comparative and population genomic data and approaches help revisiting old questions on the long-term evolution of breeding systems.
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Affiliation(s)
- Sylvain Glémin
- Institut des Sciences de l'Evolution, UMR5554, Université Montpellier II, Montpellier, France
| | - Clémentine M François
- Institut des Sciences de l'Evolution, UMR5554, Université Montpellier II, Montpellier, France
| | - Nicolas Galtier
- Institut des Sciences de l'Evolution, UMR5554, Université Montpellier II, Montpellier, France.
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20
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Chen ECH, Mathieu S, Hoffrichter A, Sedzielewska-Toro K, Peart M, Pelin A, Ndikumana S, Ropars J, Dreissig S, Fuchs J, Brachmann A, Corradi N. Single nucleus sequencing reveals evidence of inter-nucleus recombination in arbuscular mycorrhizal fungi. eLife 2018; 7:e39813. [PMID: 30516133 PMCID: PMC6281316 DOI: 10.7554/elife.39813] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Accepted: 11/16/2018] [Indexed: 12/18/2022] Open
Abstract
Eukaryotes thought to have evolved clonally for millions of years are referred to as ancient asexuals. The oldest group among these are the arbuscular mycorrhizal fungi (AMF), which are plant symbionts harboring hundreds of nuclei within one continuous cytoplasm. Some AMF strains (dikaryons) harbor two co-existing nucleotypes but there is no direct evidence that such nuclei recombine in this life-stage, as is expected for sexual fungi. Here, we show that AMF nuclei with distinct genotypes can undergo recombination. Inter-nuclear genetic exchange varies in frequency among strains, and despite recombination all nuclear genomes have an average similarity of at least 99.8%. The present study demonstrates that AMF can generate genetic diversity via meiotic-like processes in the absence of observable mating. The AMF dikaryotic life-stage is a primary source of nuclear variability in these organisms, highlighting its potential for strain enhancement of these symbionts.
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Affiliation(s)
- Eric CH Chen
- Department of BiologyUniversity of OttawaOttawaCanada
| | | | - Anne Hoffrichter
- Institute of Genetics, Faculty of BiologyLudwig Maximilian University of MunichMunichGermany
| | - Kinga Sedzielewska-Toro
- Institute of Genetics, Faculty of BiologyLudwig Maximilian University of MunichMunichGermany
| | - Max Peart
- Department of BiologyUniversity of OttawaOttawaCanada
| | - Adrian Pelin
- Department of BiologyUniversity of OttawaOttawaCanada
| | | | - Jeanne Ropars
- Department of BiologyUniversity of OttawaOttawaCanada
| | - Steven Dreissig
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGaterslebenGermany
| | - Jorg Fuchs
- Leibniz Institute of Plant Genetics and Crop Plant ResearchGaterslebenGermany
| | - Andreas Brachmann
- Institute of Genetics, Faculty of BiologyLudwig Maximilian University of MunichMunichGermany
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21
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Serrato-Capuchina A, Matute DR. The Role of Transposable Elements in Speciation. Genes (Basel) 2018; 9:E254. [PMID: 29762547 PMCID: PMC5977194 DOI: 10.3390/genes9050254] [Citation(s) in RCA: 95] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Revised: 04/26/2018] [Accepted: 04/26/2018] [Indexed: 01/20/2023] Open
Abstract
Understanding the phenotypic and molecular mechanisms that contribute to genetic diversity between and within species is fundamental in studying the evolution of species. In particular, identifying the interspecific differences that lead to the reduction or even cessation of gene flow between nascent species is one of the main goals of speciation genetic research. Transposable elements (TEs) are DNA sequences with the ability to move within genomes. TEs are ubiquitous throughout eukaryotic genomes and have been shown to alter regulatory networks, gene expression, and to rearrange genomes as a result of their transposition. However, no systematic effort has evaluated the role of TEs in speciation. We compiled the evidence for TEs as potential causes of reproductive isolation across a diversity of taxa. We find that TEs are often associated with hybrid defects that might preclude the fusion between species, but that the involvement of TEs in other barriers to gene flow different from postzygotic isolation is still relatively unknown. Finally, we list a series of guides and research avenues to disentangle the effects of TEs on the origin of new species.
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Affiliation(s)
- Antonio Serrato-Capuchina
- Biology Department, Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27514, USA.
| | - Daniel R Matute
- Biology Department, Genome Sciences Building, University of North Carolina, Chapel Hill, NC 27514, USA.
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22
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Schiffer PH, Polsky AL, Cole AG, Camps JIR, Kroiher M, Silver DH, Grishkevich V, Anavy L, Koutsovoulos G, Hashimshony T, Yanai I. The gene regulatory program of Acrobeloides nanus reveals conservation of phylum-specific expression. Proc Natl Acad Sci U S A 2018; 115:4459-4464. [PMID: 29626130 PMCID: PMC5924915 DOI: 10.1073/pnas.1720817115] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The evolution of development has been studied through the lens of gene regulation by examining either closely related species or extremely distant animals of different phyla. In nematodes, detailed cell- and stage-specific expression analyses are focused on the model Caenorhabditis elegans, in part leading to the view that the developmental expression of gene cascades in this species is archetypic for the phylum. Here, we compared two species of an intermediate evolutionary distance: the nematodes C. elegans (clade V) and Acrobeloides nanus (clade IV). To examine A. nanus molecularly, we sequenced its genome and identified the expression profiles of all genes throughout embryogenesis. In comparison with C. elegans, A. nanus exhibits a much slower embryonic development and has a capacity for regulative compensation of missing early cells. We detected conserved stages between these species at the transcriptome level, as well as a prominent middevelopmental transition, at which point the two species converge in terms of their gene expression. Interestingly, we found that genes originating at the dawn of the Ecdysozoa supergroup show the least expression divergence between these two species. This led us to detect a correlation between the time of expression of a gene and its phylogenetic age: evolutionarily ancient and young genes are enriched for expression in early and late embryogenesis, respectively, whereas Ecdysozoa-specific genes are enriched for expression during the middevelopmental transition. Our results characterize the developmental constraints operating on each individual embryo in terms of developmental stages and genetic evolutionary history.
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Affiliation(s)
- Philipp H Schiffer
- Centre for Life's Origins and Evolution, Department of Genetics, Evolution and Environment, University College London, London WC1E 6BT, United Kingdom
| | - Avital L Polsky
- Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Alison G Cole
- Department of Molecular Evolution and Development, University of Vienna, 1090 Vienna, Austria
| | - Julia I R Camps
- Molecular Cell Biology, Institute I for Anatomy University Clinic Cologne, University of Cologne, 50937 Cologne, Germany
| | - Michael Kroiher
- Zoological Institute, Cologne Biocenter, University of Cologne, 50674 Cologne, Germany
| | - David H Silver
- Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | | | - Leon Anavy
- Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Georgios Koutsovoulos
- School of Biological Sciences, University of Edinburgh, Edinburgh EH9 3JW, United Kingdom
| | - Tamar Hashimshony
- Department of Biology, Technion-Israel Institute of Technology, 32000 Haifa, Israel
| | - Itai Yanai
- Institute for Computational Medicine, NYU School of Medicine, New York, NY 10016
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23
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Warren WC, García-Pérez R, Xu S, Lampert KP, Chalopin D, Stöck M, Loewe L, Lu Y, Kuderna L, Minx P, Montague MJ, Tomlinson C, Hillier LW, Murphy DN, Wang J, Wang Z, Garcia CM, Thomas GWC, Volff JN, Farias F, Aken B, Walter RB, Pruitt KD, Marques-Bonet T, Hahn MW, Kneitz S, Lynch M, Schartl M. Clonal polymorphism and high heterozygosity in the celibate genome of the Amazon molly. Nat Ecol Evol 2018; 2:669-679. [PMID: 29434351 PMCID: PMC5866774 DOI: 10.1038/s41559-018-0473-y] [Citation(s) in RCA: 77] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2017] [Accepted: 01/09/2018] [Indexed: 12/21/2022]
Abstract
The extreme rarity of asexual vertebrates in nature is generally explained by genomic decay due to absence of meiotic recombination, thus leading to extinction of such lineages. We explore features of a vertebrate asexual genome, the Amazon molly, Poecilia formosa, and find few signs of genetic degeneration but unique genetic variability and ongoing evolution. We uncovered a substantial clonal polymorphism and, as a conserved feature from its interspecific hybrid origin, a 10-fold higher heterozygosity than in the sexual parental species. These characteristics seem to be a principal reason for the unpredicted fitness of this asexual vertebrate. Our data suggest that asexual vertebrate lineages are scarce not because they are at a disadvantage, but because the genomic combinations required to bypass meiosis and to make up a functioning hybrid genome are rarely met in nature.
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Affiliation(s)
- Wesley C. Warren
- McDonnell Genome Institute, Washington University School of Medicine, St Louis, MO 63108, USA
| | | | - Sen Xu
- Department of Biology, University of Texas at Arlington, Arlington, Texas, 76019, USA
| | - Kathrin P. Lampert
- Department of Animal Ecology, Evolution and Biodiversity, Ruhr-Universität Bochum, 44780 Bochum, Germany
| | - Domitille Chalopin
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon I, Lyon, France
| | - Matthias Stöck
- Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Berlin, Germany
| | - Laurence Loewe
- Laboratory of Genetics and Wisconsin Institute for Discovery, University of Wisconsin-Madison, Madison, WI, 53715, USA
| | - Yuan Lu
- Texas State University, Department of Chemistry and Biochemistry, San Marcos, TX 78666, USA
| | - Lukas Kuderna
- Institute of Evolutionary Biology (UPF-CSIC), PRBB, 08003 Barcelona, Spain
| | - Patrick Minx
- McDonnell Genome Institute, Washington University School of Medicine, St Louis, MO 63108, USA
| | - Michael J. Montague
- Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Chad Tomlinson
- McDonnell Genome Institute, Washington University School of Medicine, St Louis, MO 63108, USA
| | - LaDeana W. Hillier
- McDonnell Genome Institute, Washington University School of Medicine, St Louis, MO 63108, USA
| | - Daniel N. Murphy
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SD, United Kingdom
| | - John Wang
- Biodiversity Research Center, Academica Sinica Taipei, Taiwan
| | - Zhongwei Wang
- Department of Physiological Chemistry, Biocenter, University of Würzburg, 97074 Würzburg, Germany; present address: Institute of Hydrobiology, Chinese Academy of Sciences, China
| | - Constantino Macias Garcia
- Instituto de Ecología, Universidad Nacional Autónoma de México, CP 04510, Ciudad Universitaria, México DF
| | | | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, CNRS, Université Lyon I, Lyon, France
| | - Fabiana Farias
- McDonnell Genome Institute, Washington University School of Medicine, St Louis, MO 63108, USA
| | - Bronwen Aken
- European Molecular Biology Laboratory, European Bioinformatics Institute, Wellcome Genome Campus, Hinxton, Cambridge, CB10 1SD, United Kingdom
| | - Ronald B. Walter
- Texas State University, Department of Chemistry and Biochemistry, San Marcos, TX 78666, USA
| | - Kim D. Pruitt
- National Center for Biotechnology Information, National Library of Medicine, National Institutes of Health, Bethesda, MD 20894, USA
| | - Tomas Marques-Bonet
- Institute of Evolutionary Biology (UPF-CSIC), PRBB, 08003 Barcelona, Spain
- Center for Genomic Regulation (CRG) Barcelona Institute of Science and Technology (BIST), 08028 Barcelona, and Catalan Institution of Research and Advanced Studies (ICREA), 08010 Barcelona, Spain
| | - Matthew W. Hahn
- Indiana University, Department of Biology, Bloomington, IN 47405, USA
| | - Susanne Kneitz
- Department of Physiological Chemistry, Biocenter, University of Würzburg, 97074 Würzburg, Germany
| | - Michael Lynch
- Indiana University, Department of Biology, Bloomington, IN 47405, USA
| | - Manfred Schartl
- Department of Physiological Chemistry, Biocenter, University of Würzburg, 97074 Würzburg, Germany
- Hagler Institute for Advanced Study and Department of Biology, Texas A&M University, College Station, TX 77843, USA, and Comprehensive Cancer Center Mainfranken, University Hospital Würzburg, 97080 Würzburg, Germany
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Nowell RW, Almeida P, Wilson CG, Smith TP, Fontaneto D, Crisp A, Micklem G, Tunnacliffe A, Boschetti C, Barraclough TG. Comparative genomics of bdelloid rotifers: Insights from desiccating and nondesiccating species. PLoS Biol 2018; 16:e2004830. [PMID: 29689044 PMCID: PMC5916493 DOI: 10.1371/journal.pbio.2004830] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2017] [Accepted: 03/19/2018] [Indexed: 12/22/2022] Open
Abstract
Bdelloid rotifers are a class of microscopic invertebrates that have existed for millions of years apparently without sex or meiosis. They inhabit a variety of temporary and permanent freshwater habitats globally, and many species are remarkably tolerant of desiccation. Bdelloids offer an opportunity to better understand the evolution of sex and recombination, but previous work has emphasised desiccation as the cause of several unusual genomic features in this group. Here, we present high-quality whole-genome sequences of 3 bdelloid species: Rotaria macrura and R. magnacalcarata, which are both desiccation intolerant, and Adineta ricciae, which is desiccation tolerant. In combination with the published assembly of A. vaga, which is also desiccation tolerant, we apply a comparative genomics approach to evaluate the potential effects of desiccation tolerance and asexuality on genome evolution in bdelloids. We find that ancestral tetraploidy is conserved among all 4 bdelloid species, but homologous divergence in obligately aquatic Rotaria genomes is unexpectedly low. This finding is contrary to current models regarding the role of desiccation in shaping bdelloid genomes. In addition, we find that homologous regions in A. ricciae are largely collinear and do not form palindromic repeats as observed in the published A. vaga assembly. Consequently, several features interpreted as genomic evidence for long-term ameiotic evolution are not general to all bdelloid species, even within the same genus. Finally, we substantiate previous findings of high levels of horizontally transferred nonmetazoan genes in both desiccating and nondesiccating bdelloid species and show that this unusual feature is not shared by other animal phyla, even those with desiccation-tolerant representatives. These comparisons call into question the proposed role of desiccation in mediating horizontal genetic transfer.
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Affiliation(s)
- Reuben W. Nowell
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
| | - Pedro Almeida
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
| | - Christopher G. Wilson
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
| | - Thomas P. Smith
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
| | - Diego Fontaneto
- National Research Council of Italy, Institute of Ecosystem Study, Verbania Pallanza, Italy
| | - Alastair Crisp
- Department of Chemical Engineering and Biotechnology, West Cambridge Site, University of Cambridge, Cambridge, United Kingdom
| | - Gos Micklem
- Department of Genetics, Cambridge Systems Biology Centre, Downing Site, University of Cambridge, Cambridge, United Kingdom
| | - Alan Tunnacliffe
- Department of Chemical Engineering and Biotechnology, West Cambridge Site, University of Cambridge, Cambridge, United Kingdom
| | - Chiara Boschetti
- Department of Chemical Engineering and Biotechnology, West Cambridge Site, University of Cambridge, Cambridge, United Kingdom
- School of Biological and Marine Sciences, Plymouth University, Portland Square Building, Plymouth, United Kingdom
| | - Timothy G. Barraclough
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot, Berkshire, United Kingdom
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25
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Abstract
Transposable elements have colonized the genomes of nearly all organisms, including fungi. Although transposable elements may sometimes provide beneficial functions to their hosts their overall impact is considered deleterious. As a result, the activity of transposable elements needs to be counterbalanced by the host genome defenses. In fungi, the primary genome defense mechanisms include repeat-induced point mutation (RIP) and methylation induced premeiotically, meiotic silencing by unpaired DNA, sex-induced silencing, cosuppression (also known as somatic quelling), and cotranscriptional RNA surveillance. Recent studies of the filamentous fungus Neurospora crassa have shown that the process of repeat recognition for RIP apparently involves interactions between coaligned double-stranded segments of chromosomal DNA. These studies have also shown that RIP can be mediated by the conserved pathway that establishes transcriptional (heterochromatic) silencing of repetitive DNA. In light of these new findings, RIP emerges as a specialized case of the general phenomenon of heterochromatic silencing of repetitive DNA.
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26
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Wallau GL, Vieira C, Loreto ÉLS. Genetic exchange in eukaryotes through horizontal transfer: connected by the mobilome. Mob DNA 2018; 9:6. [PMID: 29422954 PMCID: PMC5791352 DOI: 10.1186/s13100-018-0112-9] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2017] [Accepted: 01/24/2018] [Indexed: 12/11/2022] Open
Abstract
Background All living species contain genetic information that was once shared by their common ancestor. DNA is being inherited through generations by vertical transmission (VT) from parents to offspring and from ancestor to descendant species. This process was considered the sole pathway by which biological entities exchange inheritable information. However, Horizontal Transfer (HT), the exchange of genetic information by other means than parents to offspring, was discovered in prokaryotes along with strong evidence showing that it is a very important process by which prokaryotes acquire new genes. Main body For some time now, it has been a scientific consensus that HT events were rare and non-relevant for evolution of eukaryotic species, but there is growing evidence supporting that HT is an important and frequent phenomenon in eukaryotes as well. Conclusion Here, we will discuss the latest findings regarding HT among eukaryotes, mainly HT of transposons (HTT), establishing HTT once and for all as an important phenomenon that should be taken into consideration to fully understand eukaryotes genome evolution. In addition, we will discuss the latest development methods to detect such events in a broader scale and highlight the new approaches which should be pursued by researchers to fill the knowledge gaps regarding HTT among eukaryotes.
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Affiliation(s)
- Gabriel Luz Wallau
- 1Entomology Department, Aggeu Magalhães Institute, Oswaldo Cruz Foundation, Recife, PE Brazil
| | - Cristina Vieira
- 2Université de Lyon, Université Lyon 1, CNRS, Laboratoire de Biométrie et Biologie Evolutive, UMR5558, F-69622 Villeurbanne, France
| | - Élgion Lúcio Silva Loreto
- 3Department of Biochemistry and Molecular Biology, Federal University of Santa Maria, Santa Maria, RS Brazil
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Lenormand T, Engelstädter J, Johnston SE, Wijnker E, Haag CR. Evolutionary mysteries in meiosis. Philos Trans R Soc Lond B Biol Sci 2017; 371:rstb.2016.0001. [PMID: 27619705 DOI: 10.1098/rstb.2016.0001] [Citation(s) in RCA: 90] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/15/2016] [Indexed: 01/25/2023] Open
Abstract
Meiosis is a key event of sexual life cycles in eukaryotes. Its mechanistic details have been uncovered in several model organisms, and most of its essential features have received various and often contradictory evolutionary interpretations. In this perspective, we present an overview of these often 'weird' features. We discuss the origin of meiosis (origin of ploidy reduction and recombination, two-step meiosis), its secondary modifications (in polyploids or asexuals, inverted meiosis), its importance in punctuating life cycles (meiotic arrests, epigenetic resetting, meiotic asymmetry, meiotic fairness) and features associated with recombination (disjunction constraints, heterochiasmy, crossover interference and hotspots). We present the various evolutionary scenarios and selective pressures that have been proposed to account for these features, and we highlight that their evolutionary significance often remains largely mysterious. Resolving these mysteries will likely provide decisive steps towards understanding why sex and recombination are found in the majority of eukaryotes.This article is part of the themed issue 'Weird sex: the underappreciated diversity of sexual reproduction'.
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Affiliation(s)
- Thomas Lenormand
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
| | - Jan Engelstädter
- School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia
| | - Susan E Johnston
- Institute of Evolutionary Biology, University of Edinburgh, Charlotte Auerbach Road, Edinburgh EH9 3FL, UK
| | - Erik Wijnker
- Laboratory of Genetics, Wageningen University, Droevendaalsesteeg 1, 6708 PB Wageningen, The Netherlands
| | - Christoph R Haag
- Centre d'Ecologie Fonctionnelle et Evolutive (CEFE)-Unité Mixte de Recherche 5175, Centre National de la Recherche Scientifique (CNRS), Université de Montpellier-Université Paul-Valéry Montpellier-Ecole Pratique des Hautes Etudes (EPHE), 1919 Route de Mende, 34293 Montpellier Cedex 5, France
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28
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Jiang X, Tang H, Ye Z, Lynch M. Insertion Polymorphisms of Mobile Genetic Elements in Sexual and Asexual Populations of Daphnia pulex. Genome Biol Evol 2017; 9:362-374. [PMID: 28057730 PMCID: PMC5381639 DOI: 10.1093/gbe/evw302] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/29/2016] [Indexed: 12/20/2022] Open
Abstract
Transposable elements (TEs) constitute a substantial portion of many eukaryotic genomes, and can in principle contribute to evolutionary innovation as well as genomic deterioration. Daphnia pulex serves as a useful model for studying TE dynamics as a potential cause and/or consequence of asexuality. We analyzed insertion polymorphisms of TEs in 20 sexual and 20 asexual isolates of D. pulex across North American from their available whole-genome sequencing data. Our results show that the total fraction of the derived sequences of TEs is not substantially different between asexual and sexual D. pulex isolates. However, in general, sexual clones contain fewer fixed TE insertions but more total insertion polymorphisms than asexual clones, supporting the hypothesis that sexual reproduction facilitates the spread and elimination of TEs. We identified nine asexual-specific fixed TE insertions, eight long terminal repeat retrotransposons, and one DNA transposon. By comparison, no sexual-specific fixed TE insertions were observed in our analysis. Furthermore, except one TE insertion located on a contig from chromosome 7, the other eight asexual-specific insertion sites are located on contigs from chromosome 9 that is known to be associated with obligate asexuality in D. pulex. We found that all nine asexual-specific fixed TE insertions can also be detected in some Daphnia pulicaria isolates, indicating that a substantial number of TE insertions in asexual D. pulex have been directly inherited from D. pulicaria during the origin of obligate asexuals.
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Affiliation(s)
- Xiaoqian Jiang
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Haixu Tang
- School of Informatics and Computing, Indiana University, Bloomington, Indiana
| | - Zhiqiang Ye
- Department of Biology, Indiana University, Bloomington, Indiana
| | - Michael Lynch
- Department of Biology, Indiana University, Bloomington, Indiana
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29
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Rodriguez F, Kenefick AW, Arkhipova IR. LTR-Retrotransposons from Bdelloid Rotifers Capture Additional ORFs Shared between Highly Diverse Retroelement Types. Viruses 2017; 9:v9040078. [PMID: 28398238 PMCID: PMC5408684 DOI: 10.3390/v9040078] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/04/2017] [Accepted: 04/04/2017] [Indexed: 12/16/2022] Open
Abstract
Rotifers of the class Bdelloidea, microscopic freshwater invertebrates, possess a highlydiversified repertoire of transposon families, which, however, occupy less than 4% of genomic DNA in the sequenced representative Adineta vaga. We performed a comprehensive analysis of A. vaga retroelements, and found that bdelloid long terminal repeat (LTR)retrotransposons, in addition to conserved open reading frame (ORF) 1 and ORF2 corresponding to gag and pol genes, code for an unusually high variety of ORF3 sequences. Retrovirus-like LTR families in A. vaga belong to four major lineages, three of which are rotiferspecific and encode a dUTPase domain. However only one lineage contains a canonical envlike fusion glycoprotein acquired from paramyxoviruses (non-segmented negative-strand RNA viruses), although smaller ORFs with transmembrane domains may perform similar roles. A different ORF3 type encodes a GDSL esterase/lipase, which was previously identified as ORF1 in several clades of non-LTR retrotransposons, and implicated in membrane targeting. Yet another ORF3 type appears in unrelated LTR-retrotransposon lineages, and displays strong homology to DEDDy-type exonucleases involved in 3'-end processing of RNA and single-stranded DNA. Unexpectedly, each of the enzymatic ORF3s is also associated with different subsets of Penelope-like Athena retroelement families. The unusual association of the same ORF types with retroelements from different classes reflects their modular structure with a high degree of flexibility, and points to gene sharing between different groups of retroelements.
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Affiliation(s)
- Fernando Rodriguez
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA.
| | - Aubrey W Kenefick
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA.
- Present address: UC Davis Genome Center-GBSF, University of California, Davis, CA 95616, USA.
| | - Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, 7 MBL Street, Woods Hole, MA 02543, USA.
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30
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Multitasking of the piRNA Silencing Machinery: Targeting Transposable Elements and Foreign Genes in the Bdelloid Rotifer Adineta vaga. Genetics 2016; 203:255-68. [PMID: 27017627 DOI: 10.1534/genetics.116.186734] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Accepted: 03/21/2016] [Indexed: 12/12/2022] Open
Abstract
RNA-mediated silencing processes play a key role in silencing of transposable elements, especially in the germ line, where piwi-interacting RNAs (piRNAs) are responsible for suppressing transposon mobility and maintaining genome integrity. We previously reported that the genome of Adineta vaga, the first sequenced representative of the phylum Rotifera (class Bdelloidea), is characterized by massive levels of horizontal gene transfer, by unusually low transposon content, and by highly diversified RNA-mediated silencing machinery. Here, we investigate genome-wide distribution of pi-like small RNAs, which in A. vaga are 25-31 nucleotides in length and have a strong 5'-uridine bias, while lacking ping-pong amplification signatures. In agreement with expectations, 71% of mapped reads corresponded to annotated transposons, with 93% of these reads being in the antisense orientation. Unexpectedly, a significant fraction of piRNAs originate from predicted coding regions corresponding to genes of putatively foreign origin. The distribution of piRNAs across foreign genes is not biased toward 3'-UTRs, instead resembling transposons in uniform distribution pattern throughout the gene body, and in predominantly antisense orientation. We also find that genes with small RNA coverage, including a number of genes of metazoan origin, are characterized by higher occurrence of telomeric repeats in the surrounding genomic regions, and by higher density of transposons in the vicinity, which have the potential to promote antisense transcription. Our findings highlight the complex interplay between RNA-based silencing processes and acquisition of genes at the genome periphery, which can result either in their loss or eventual domestication and integration into the host genome.
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31
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Ferreira de Carvalho J, Oplaat C, Pappas N, Derks M, de Ridder D, Verhoeven KJF. Heritable gene expression differences between apomictic clone members in Taraxacum officinale: Insights into early stages of evolutionary divergence in asexual plants. BMC Genomics 2016; 17:203. [PMID: 26956152 PMCID: PMC4782324 DOI: 10.1186/s12864-016-2524-6] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 02/24/2016] [Indexed: 12/21/2022] Open
Abstract
BACKGROUND Asexual reproduction has the potential to enhance deleterious mutation accumulation and to constrain adaptive evolution. One source of mutations that can be especially relevant in recent asexuals is activity of transposable elements (TEs), which may have experienced selection for high transposition rates in sexual ancestor populations. Predictions of genomic divergence under asexual reproduction therefore likely include a large contribution of transposable elements but limited adaptive divergence. For plants empirical insight into genome divergence under asexual reproduction remains limited. Here, we characterize expression divergence between clone members of a single apomictic lineage of the common dandelion (Taraxacum officinale) to contribute to our knowledge of genome evolution under asexuality. RESULTS Using RNA-Seq, we show that about one third of heritable divergence within the apomictic lineage is driven by TEs and TE-related gene activity. In addition, we identify non-random transcriptional differences in pathways related to acyl-lipid and abscisic acid metabolisms which might reflect functional divergence within the apomictic lineage. We analyze SNPs in the transcriptome to assess genetic divergence between the apomictic clone members and reveal that heritable expression differences between the accessions are not explained simply by genome-wide genetic divergence. CONCLUSION The present study depicts a first effort towards a more complete understanding of apomictic plant genome evolution. We identify abundant TE activity and ecologically relevant functional genes and pathways affecting heritable within-lineage expression divergence. These findings offer valuable resources for future work looking at epigenetic silencing and Cis-regulation of gene expression with particular emphasis on the effects of TE activity on asexual species' genome.
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Affiliation(s)
- Julie Ferreira de Carvalho
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
| | - Carla Oplaat
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
| | - Nikolaos Pappas
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
| | - Martijn Derks
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
| | - Dick de Ridder
- Bioinformatics Group, Wageningen University, Droevendaalsesteeg 1, 6708 PB, Wageningen, The Netherlands.
| | - Koen J F Verhoeven
- Department of Terrestrial Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB, Wageningen, The Netherlands.
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32
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Wu Y, Aandahl RZ, Tanaka MM. Dynamics of bacterial insertion sequences: can transposition bursts help the elements persist? BMC Evol Biol 2015; 15:288. [PMID: 26690348 PMCID: PMC4687120 DOI: 10.1186/s12862-015-0560-5] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 12/06/2015] [Indexed: 01/22/2023] Open
Abstract
Background Currently there is no satisfactory explanation for why bacterial insertion sequences (ISs) widely occur across prokaryotes despite being mostly harmful to their host genomes. Rates of horizontal gene transfer are likely to be too low to maintain ISs within a population. IS-induced beneficial mutations may be important for both prevalence of ISs and microbial adaptation to changing environments but may be too rare to sustain IS elements in the long run. Environmental stress can induce elevated rates of IS transposition activities; such episodes are known as ‘transposition bursts’. By examining how selective forces and transposition events interact to influence IS dynamics, this study asks whether transposition bursts can lead to IS persistence. Results We show through a simulation model that ISs are gradually eliminated from a population even if IS transpositions occasionally cause advantageous mutations. With beneficial mutations, transposition bursts create variation in IS copy numbers and improve cell fitness on average. However, these benefits are not usually sufficient to overcome the negative selection against the elements, and transposition bursts amplify the mean fitness effect which, if negative, simply accelerates the extinction of ISs. If down regulation of transposition occurs, IS extinctions are reduced while ISs still generate variation amongst bacterial genomes. Conclusions Transposition bursts do not help ISs persist in a bacterial population in the long run because most burst-induced mutations are deleterious and therefore not favoured by natural selection. However, bursts do create more genetic variation through which occasional advantageous mutations can help organisms adapt. Regulation of IS transposition bursts and stronger positive selection of the elements interact to slow down the burst-induced extinction of ISs. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0560-5) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Yue Wu
- School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney, 2052, NSW, Australia. .,Evolution & Ecology Research Centre, University of New South Wales, Sydney, 2052, NSW, Australia. .,Present address: Telethon Kids Institute, University of Western Australia, Perth, 6008, WA, Australia.
| | - Richard Z Aandahl
- School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney, 2052, NSW, Australia. .,Evolution & Ecology Research Centre, University of New South Wales, Sydney, 2052, NSW, Australia.
| | - Mark M Tanaka
- School of Biotechnology & Biomolecular Sciences, University of New South Wales, Sydney, 2052, NSW, Australia. .,Evolution & Ecology Research Centre, University of New South Wales, Sydney, 2052, NSW, Australia.
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Maurer-Alcalá XX, Katz LA. An epigenetic toolkit allows for diverse genome architectures in eukaryotes. Curr Opin Genet Dev 2015; 35:93-9. [PMID: 26649755 DOI: 10.1016/j.gde.2015.10.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2015] [Revised: 10/21/2015] [Accepted: 10/22/2015] [Indexed: 02/04/2023]
Abstract
Genome architecture varies considerably among eukaryotes in terms of both size and structure (e.g. distribution of sequences within the genome, elimination of DNA during formation of somatic nuclei). The diversity in eukaryotic genome architectures and the dynamic processes are only possible due to the well-developed epigenetic toolkit, which probably existed in the Last Eukaryotic Common Ancestor (LECA). This toolkit may have arisen as a means of navigating the genomic conflict that arose from the expansion of transposable elements within the ancestral eukaryotic genome. This toolkit has been coopted to support the dynamic nature of genomes in lineages across the eukaryotic tree of life. Here we highlight how the changes in genome architecture in diverse eukaryotes are regulated by epigenetic processes, such as DNA elimination, genome rearrangements, and adaptive changes to genome architecture. The ability to epigenetically modify and regulate genomes has contributed greatly to the diversity of eukaryotes observed today.
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Affiliation(s)
- Xyrus X Maurer-Alcalá
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA; Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA
| | - Laura A Katz
- Department of Biological Sciences, Smith College, Northampton, MA 01063, USA; Program in Organismic and Evolutionary Biology, University of Massachusetts, Amherst, MA 01003, USA.
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34
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Bast J, Schaefer I, Schwander T, Maraun M, Scheu S, Kraaijeveld K. No Accumulation of Transposable Elements in Asexual Arthropods. Mol Biol Evol 2015; 33:697-706. [PMID: 26560353 PMCID: PMC4760076 DOI: 10.1093/molbev/msv261] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
Transposable elements (TEs) and other repetitive DNA can accumulate in the absence of recombination, a process contributing to the degeneration of Y-chromosomes and other nonrecombining genome portions. A similar accumulation of repetitive DNA is expected for asexually reproducing species, given their entire genome is effectively nonrecombining. We tested this expectation by comparing the whole-genome TE loads of five asexual arthropod lineages and their sexual relatives, including asexual and sexual lineages of crustaceans (Daphnia water fleas), insects (Leptopilina wasps), and mites (Oribatida). Surprisingly, there was no evidence for increased TE load in genomes of asexual as compared to sexual lineages, neither for all classes of repetitive elements combined nor for specific TE families. Our study therefore suggests that nonrecombining genomes do not accumulate TEs like nonrecombining genomic regions of sexual lineages. Even if a slight but undetected increase of TEs were caused by asexual reproduction, it appears to be negligible compared to variance between species caused by processes unrelated to reproductive mode. It remains to be determined if molecular mechanisms underlying genome regulation in asexuals hamper TE activity. Alternatively, the differences in TE dynamics between nonrecombining genomes in asexual lineages versus nonrecombining genome portions in sexual species might stem from selection for benign TEs in asexual lineages because of the lack of genetic conflict between TEs and their hosts and/or because asexual lineages may only arise from sexual ancestors with particularly low TE loads.
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Affiliation(s)
- Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Ina Schaefer
- J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Goettingen, Goettingen, Germany
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Mark Maraun
- J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Goettingen, Goettingen, Germany
| | - Stefan Scheu
- J.F. Blumenbach Institute of Zoology and Anthropology, Georg August University Goettingen, Goettingen, Germany
| | - Ken Kraaijeveld
- Department of Ecological Science, VU University Amsterdam, Amsterdam, The Netherlands Leiden Genome Technology Center, Department of Human genetics, Leiden University Medical Center, Leiden, The Netherlands
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Xiong TL, Xiao JH, Li YX, Bian SN, Huang DW. Diversity and evolution of Ty1-copia retroelements within Chalcidoidea by reverse transcriptase domain analysis. INSECT MOLECULAR BIOLOGY 2015; 24:503-516. [PMID: 26079156 DOI: 10.1111/imb.12167] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Ty1-copia retrotransposons are widespread and diverse in insects. Some features of their hosts, such as mating and genetic systems, are predicted to influence the spread of selfish genetic elements like Ty1-copia. Using part of the reverse transcriptase gene as a reference, we experimentally surveyed Ty1-copia elements in eight species of fig wasps (Hymenoptera: Chalcidoidea), and performed an in silico analysis of six available genomes of chalcid wasps. Contrary to initial expectations that selfish elements such as Ty1-copia would be purged from the genomes of these species because of inbreeding and haplodiploidy, almost all of these wasps harbour an abundance of diverse Ty1-copia elements. Phylogenetic analyses suggest that the families of Ty1-copia elements found in these species have had a long association with their chalcid hosts. These results suggest an evolutionary scenario in which there was ancestral polymorphism followed by some taxa-specific events including stochastic loss and further diversification. Furthermore, estimating natural selection within the internal and terminal portions of the Ty1-copia phylogenies demonstrated that the elements are under strong evolutionary constraints for their long-term survival, but evolve like pseudogenes in the short term, accompanied by the rise and fall of parasitic elements in the history of wasp lineage.
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Affiliation(s)
- T-L Xiong
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- University of Chinese Academy of Sciences, Beijing, 100039, China
| | - J-H Xiao
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
| | - Y-X Li
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Plant Protection, Shandong Agricultural University, Tai'an, 271018, China
| | - S-N Bian
- College of Plant Protection, Shandong Agricultural University, Tai'an, 271018, China
| | - D-W Huang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, 100101, China
- College of Plant Protection, Shandong Agricultural University, Tai'an, 271018, China
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Speijer D, Lukeš J, Eliáš M. Sex is a ubiquitous, ancient, and inherent attribute of eukaryotic life. Proc Natl Acad Sci U S A 2015; 112:8827-34. [PMID: 26195746 PMCID: PMC4517231 DOI: 10.1073/pnas.1501725112] [Citation(s) in RCA: 171] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
Sexual reproduction and clonality in eukaryotes are mostly seen as exclusive, the latter being rather exceptional. This view might be biased by focusing almost exclusively on metazoans. We analyze and discuss reproduction in the context of extant eukaryotic diversity, paying special attention to protists. We present results of phylogenetically extended searches for homologs of two proteins functioning in cell and nuclear fusion, respectively (HAP2 and GEX1), providing indirect evidence for these processes in several eukaryotic lineages where sex has not been observed yet. We argue that (i) the debate on the relative significance of sex and clonality in eukaryotes is confounded by not appropriately distinguishing multicellular and unicellular organisms; (ii) eukaryotic sex is extremely widespread and already present in the last eukaryotic common ancestor; and (iii) the general mode of existence of eukaryotes is best described by clonally propagating cell lines with episodic sex triggered by external or internal clues. However, important questions concern the relative longevity of true clonal species (i.e., species not able to return to sexual procreation anymore). Long-lived clonal species seem strikingly rare. We analyze their properties in the light of meiotic sex development from existing prokaryotic repair mechanisms. Based on these considerations, we speculate that eukaryotic sex likely developed as a cellular survival strategy, possibly in the context of internal reactive oxygen species stress generated by a (proto) mitochondrion. Thus, in the context of the symbiogenic model of eukaryotic origin, sex might directly result from the very evolutionary mode by which eukaryotic cells arose.
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Affiliation(s)
- Dave Speijer
- Department of Medical Biochemistry, Academic Medical Center, University of Amsterdam, 1105 AZ, Amsterdam, The Netherlands;
| | - Julius Lukeš
- Institute of Parasitology, Biology Centre, Czech Academy of Sciences, and Faculty of Sciences, University of South Bohemia, 370 05 České Budějovice, Czech Republic; Canadian Institute for Advanced Research, Toronto, ON, Canada M5G 1Z8
| | - Marek Eliáš
- Department of Biology and Ecology, University of Ostrava, 710 00 Ostrava, Czech Republic
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Kemen AC, Agler MT, Kemen E. Host-microbe and microbe-microbe interactions in the evolution of obligate plant parasitism. THE NEW PHYTOLOGIST 2015; 206:1207-28. [PMID: 25622918 DOI: 10.1111/nph.13284] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2014] [Accepted: 12/12/2014] [Indexed: 05/03/2023]
Abstract
Research on obligate biotrophic plant parasites, which reproduce only on living hosts, has revealed a broad diversity of filamentous microbes that have independently acquired complex morphological structures, such as haustoria. Genome studies have also demonstrated a concerted loss of genes for metabolism and lytic enzymes, and gain of diversity of genes coding for effectors involved in host defense suppression. So far, these traits converge in all known obligate biotrophic parasites, but unexpected genome plasticity remains. This plasticity is manifested as transposable element (TE)-driven increases in genome size, observed to be associated with the diversification of virulence genes under selection pressure. Genome expansion could result from the governing of the pathogen response to ecological selection pressures, such as host or nutrient availability, or to microbial interactions, such as competition, hyperparasitism and beneficial cooperations. Expansion is balanced by alternating sexual and asexual cycles, as well as selfing and outcrossing, which operate to control transposon activity in populations. In turn, the prevalence of these balancing mechanisms seems to be correlated with external biotic factors, suggesting a complex, interconnected evolutionary network in host-pathogen-microbe interactions. Therefore, the next phase of obligate biotrophic pathogen research will need to uncover how this network, including multitrophic interactions, shapes the evolution and diversity of pathogens.
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Affiliation(s)
- Ariane C Kemen
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Plant Breeding Research, Carl-von-Linne Weg 10, 50829, Cologne, Germany
| | - Matthew T Agler
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Plant Breeding Research, Carl-von-Linne Weg 10, 50829, Cologne, Germany
| | - Eric Kemen
- Max Planck Research Group Fungal Biodiversity, Max Planck Institute for Plant Breeding Research, Carl-von-Linne Weg 10, 50829, Cologne, Germany
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Fontaneto D, Barraclough TG. Do Species Exist in Asexuals? Theory and Evidence from Bdelloid Rotifers. Integr Comp Biol 2015; 55:253-63. [PMID: 25912362 DOI: 10.1093/icb/icv024] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The possibility for independently evolving entities to form and persist in the absence of sexual recombination in eukaryotes has been questioned; nevertheless, there are organisms that are known to be asexual and that have apparently diversified into multiple species as recognized by taxonomists. These organisms have therefore been identified as an evolutionary paradox. We explore three alternative hypotheses attempting to solve the apparent paradox, focusing on bdelloid rotifers, the most studied group of organisms in which all species are considered asexual: (1) they may have some hidden form of sex; (2) species do not represent biological entities but simply convenient names; and (3) sex may not be a necessary requirement for speciation. We provide ample evidence against the first two hypotheses, reporting several studies supporting (1) bdelloids asexuality from different approaches, and (2) the existence of species from genetics, jaw morphology, ecology, and physiology. Thus, we (3) explore the role of sex in speciation comparing bdelloid and monogonont rotifers, and conclude with some caveats that could still change our understanding of bdelloid species.
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Affiliation(s)
- Diego Fontaneto
- *National Research Council, Institute of Ecosystem Study, Largo Tonolli 50, 28922 Verbania Pallanza, Italy;
| | - Timothy G Barraclough
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Ascot SL5 7PY, UK
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Ågren JA, Greiner S, Johnson MTJ, Wright SI. No evidence that sex and transposable elements drive genome size variation in evening primroses. Evolution 2015; 69:1053-62. [PMID: 25690700 DOI: 10.1111/evo.12627] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2014] [Accepted: 01/13/2015] [Indexed: 01/05/2023]
Abstract
Genome size varies dramatically across species, but despite an abundance of attention there is little agreement on the relative contributions of selective and neutral processes in governing this variation. The rate of sex can potentially play an important role in genome size evolution because of its effect on the efficacy of selection and transmission of transposable elements (TEs). Here, we used a phylogenetic comparative approach and whole genome sequencing to investigate the contribution of sex and TE content to genome size variation in the evening primrose (Oenothera) genus. We determined genome size using flow cytometry for 30 species that vary in genetic system and find that variation in sexual/asexual reproduction cannot explain the almost twofold variation in genome size. Moreover, using whole genome sequences of three species of varying genome sizes and reproductive system, we found that genome size was not associated with TE abundance; instead the larger genomes had a higher abundance of simple sequence repeats. Although it has long been clear that sexual reproduction may affect various aspects of genome evolution in general and TE evolution in particular, it does not appear to have played a major role in genome size evolution in the evening primroses.
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Affiliation(s)
- J Arvid Ågren
- Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, M5S 3B2, Canada.
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40
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Castagnone-Sereno P, Danchin EGJ. Parasitic success without sex – the nematode experience. J Evol Biol 2015; 27:1323-33. [PMID: 25105196 DOI: 10.1111/jeb.12337] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Asexual reproduction is usually considered as an evolutionary dead end, and difficulties for asexual lineages to adapt to a fluctuating environment are anticipated due to the lack of sufficient genetic plasticity. Yet, unlike their sexual congeners, mitotic parthenogenetic root-knot nematode species, Meloidogyne spp., are remarkably widespread and polyphagous, with the ability to parasitize most flowering plants. Although this may reflect in part the short-term stability of agricultural environments, the extreme parasitic success of these clonal species points them as an outstanding evolutionary paradox regarding current theories on the benefits of sex. The discovery that most of the genome of the clonal species M. incognita is composed of pairs of homologous but divergent segments that have presumably been evolving independently in the absence of sexual recombination has shed new light on this evolutionary paradox. Together with recent studies on other biological systems, including the closely related sexual species M. hapla and the ancient asexual bdelloid rotifers, this observation suggests that functional innovation could emerge from such a peculiar genome architecture, which may in turn account for the extreme adaptive capacities of these asexual parasites. Additionally, the higher proportion of transposable elements in M. incognita compared to M. hapla and other nematodes may also be responsible in part for genome plasticity in the absence of sexual reproduction. We foresee that ongoing sequencing efforts should lead soon to a genomic framework involving genetically diverse Meloidogyne species with various different reproductive modes. This will undoubtedly promote the entire genus as a unique and valuable model system to help deciphering the evolution of asexual reproduction in eukaryotes.
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Jalasvuori M, Lehtonen J. Virus epidemics can lead to a population-wide spread of intragenomic parasites in a previously parasite-free asexual population. Mol Ecol 2014; 23:987-91. [PMID: 24400851 DOI: 10.1111/mec.12662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2012] [Revised: 11/15/2013] [Accepted: 12/27/2013] [Indexed: 12/29/2022]
Abstract
Sexual reproduction is problematic to explain due to its costs, most notably the twofold cost of sex. Yet, sex has been suggested to be favourable in the presence of proliferating intragenomic parasites given that sexual recombination provides a mechanism to confine the accumulation of deleterious mutations. Kraaijeveld et al. compared recently the accumulation of transposons in sexually and asexually reproducing lines of the same species, the parasitoid wasp Leptopilina clavipes. They discovered that within asexually reproducing wasps, the number of gypsy-like retrotransposons was increased fourfold, whereas other retrotransposons were not. Interestingly, gypsy-like retrotransposons are closely related to retroviruses. Endogenous retroviruses are retroviruses that have integrated to the germ line cells and are inherited thereafter vertically. They can also replicate within the genome similarly to retrotransposons as well as form virus particles and infect previously uninfected cells. This highlights the possibility that endogenous retroviruses could play a role in the evolution of sexual reproduction. Here, we show with an individual-based computational model that a virus epidemic within a previously parasite-free asexual population may establish a new intragenomic parasite to the population. Moreover and in contrast to other transposons, the possibility of endogenous viruses to maintain a virus epidemic and simultaneously provide resistance to individuals carrying active endogenous viruses selects for the presence of active intragenomic parasites in the population despite their deleterious effects. Our results suggest that the viral nature of certain intragenomic parasites should be taken into account when sex and its benefits are being considered.
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Affiliation(s)
- Matti Jalasvuori
- Division of Evolution Ecology and Genetics, Centre of Excellence in Biological Interactions, Research School of Biology, The Australian National University, Canberra, ACT, 0200, Australia; Department of Biological and Environmental Science, Centre of Excellence in Biological Interactions, University of Jyväskylä, PO Box 35, Jyväskylä, 40014, Finland
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Ricci M, Luchetti A, Bonandin L, Mantovani B. Random DNA libraries from three species of the stick insect genus Bacillus (Insecta: Phasmida): repetitive DNA characterization and first observation of polyneopteran MITEs. Genome 2013; 56:729-35. [PMID: 24433208 DOI: 10.1139/gen-2013-0107] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
The repetitive DNA content of the stick insect species Bacillus rossius (facultative parthenogenetic), Bacillus grandii (gonochoric), and Bacillus atticus (obligate parthenogenetic) was analyzed through the survey of random genomic libraries roughly corresponding to 0.006% of the genome. By repeat masking, 19 families of transposable elements were identified (two LTR and six non-LTR retrotransposons; 11 DNA transposons). Moreover, a de novo analysis revealed, among the three libraries, the first MITE family observed in polyneopteran genomes. On the whole, transposable element abundance represented 23.3% of the genome in B. rossius, 22.9% in B. atticus, and 18% in B. grandii. Tandem repeat content in the three libraries is much lower: 1.32%, 0.64%, and 1.86% in B. rossius, B. grandii, and B. atticus, respectively. Microsatellites are the most abundant in all species. Minisatellites were only found in B. rossius and B. atticus, and five monomers belonging to the Bag320 satellite family were detected in B. atticus. Assuming the survey provides adequate representation of the relative genome, the obligate parthenogenetic species (B. atticus), compared with the other two species analyzed, does not show a lower transposable element content, as expected from some theoretical and empirical studies.
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Affiliation(s)
- Marco Ricci
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali (BiGeA), Università di Bologna, via Selmi 3, 40126 Bologna, Italy
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Startek M, Le Rouzic A, Capy P, Grzebelus D, Gambin A. Genomic parasites or symbionts? Modeling the effects of environmental pressure on transposition activity in asexual populations. Theor Popul Biol 2013; 90:145-51. [PMID: 23948701 DOI: 10.1016/j.tpb.2013.07.004] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2012] [Revised: 07/17/2013] [Accepted: 07/25/2013] [Indexed: 11/17/2022]
Abstract
Transposable elements are DNA segments capable of persisting in host genomes by self-replication in spite of deleterious mutagenic effects. The theoretical dynamics of these elements within genomes has been studied extensively, and population genetic models predict that they can invade and maintain as a result of both intra-genomic and inter-individual selection in sexual species. In asexuals, the success of selfish DNA is more difficult to explain. However, most theoretical work assumes constant environment. Here, we analyze the impact of environmental change on the dynamics of transposition activity when horizontal DNA exchange is absent, based on a stochastic computational model of transposable element proliferation. We argue that repeated changes in the phenotypic optimum in a multidimensional fitness landscape may induce explosive bursts of transposition activity associated with faster adaptation. However, long-term maintenance of transposition activity is unlikely. This could contribute to the significant variation in the transposable element copy number among closely related species.
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Affiliation(s)
- Michał Startek
- College of Inter-Faculty Individual Studies in Mathematics and Natural Sciences, University of Warsaw, Poland
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Genomic evidence for ameiotic evolution in the bdelloid rotifer Adineta vaga. Nature 2013; 500:453-7. [PMID: 23873043 DOI: 10.1038/nature12326] [Citation(s) in RCA: 247] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Accepted: 05/30/2013] [Indexed: 11/08/2022]
Abstract
Loss of sexual reproduction is considered an evolutionary dead end for metazoans, but bdelloid rotifers challenge this view as they appear to have persisted asexually for millions of years. Neither male sex organs nor meiosis have ever been observed in these microscopic animals: oocytes are formed through mitotic divisions, with no reduction of chromosome number and no indication of chromosome pairing. However, current evidence does not exclude that they may engage in sex on rare, cryptic occasions. Here we report the genome of a bdelloid rotifer, Adineta vaga (Davis, 1873), and show that its structure is incompatible with conventional meiosis. At gene scale, the genome of A. vaga is tetraploid and comprises both anciently duplicated segments and less divergent allelic regions. However, in contrast to sexual species, the allelic regions are rearranged and sometimes even found on the same chromosome. Such structure does not allow meiotic pairing; instead, we find abundant evidence of gene conversion, which may limit the accumulation of deleterious mutations in the absence of meiosis. Gene families involved in resistance to oxidation, carbohydrate metabolism and defence against transposons are significantly expanded, which may explain why transposable elements cover only 3% of the assembled sequence. Furthermore, 8% of the genes are likely to be of non-metazoan origin and were probably acquired horizontally. This apparent convergence between bdelloids and prokaryotes sheds new light on the evolutionary significance of sex.
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Arkhipova IR, Rodriguez F. Genetic and epigenetic changes involving (retro)transposons in animal hybrids and polyploids. Cytogenet Genome Res 2013; 140:295-311. [PMID: 23899811 DOI: 10.1159/000352069] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Transposable elements (TEs) are discrete genetic units that have the ability to change their location within chromosomal DNA, and constitute a major and rapidly evolving component of eukaryotic genomes. They can be subdivided into 2 distinct types: retrotransposons, which use an RNA intermediate for transposition, and DNA transposons, which move only as DNA. Rapid advances in genome sequencing significantly improved our understanding of TE roles in genome shaping and restructuring, and studies of transcriptomes and epigenomes shed light on the previously unknown molecular mechanisms underlying genetic and epigenetic TE controls. Knowledge of these control systems may be important for better understanding of reticulate evolution and speciation in the context of bringing different genomes together by hybridization and perturbing the established regulatory balance by ploidy changes. See also sister article focusing on plants by Bento et al. in this themed issue.
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Affiliation(s)
- I R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA. iarkhipova @ mbl.edu
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Fischer C, Ahlrichs WH, Buma AGJ, van de Poll WH, Bininda-Emonds ORP. How does the 'ancient' asexual Philodina roseola (Rotifera: Bdelloidea) handle potential UVB-induced mutations? ACTA ACUST UNITED AC 2013; 216:3090-5. [PMID: 23619410 DOI: 10.1242/jeb.087064] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Like other obligate asexuals, bdelloid rotifers are expected to suffer from degradation of their genomes through processes including the accumulation of deleterious mutations. However, sequence-based analyses in this regard remain inconclusive. Instead of looking for historical footprints of mutations in these ancient asexuals, we directly examined the susceptibility and ability to repair point mutations by the bdelloid Philodina roseola by inducing cyclobutane-pyrimidine dimers (CPDs) via exposure to UVB radiation (280-320 nm). For comparison, we performed analogous experiments with the facultative asexual monogonont rotifer Brachionus rubens. Different strategies were found for the two species. Philodina roseola appeared to shield itself from CPD induction through uncharacterized UV-absorbing compounds and, except for the genome reconstruction that occurs after desiccation, was largely unable to repair UVB-induced damage. By contrast, B. rubens was more susceptible to UVB irradiation, but could repair all induced damage in ~2 h. In addition, whereas UV irradiation had a significant negative impact on the reproductive output of P. roseola, and especially so after desiccation, that of B. rubens was unaffected. Although the strategy of P. roseola might suffice under natural conditions where UVB irradiation is less intense, the lack of any immediate CPD repair mechanisms in this species remains perplexing. It remains to be investigated how typical these results are for bdelloids as a group and therefore how reliant these animals are on desiccation-dependent genome repair to correct potential DNA damage given their obligate asexual lifestyle.
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Affiliation(s)
- Claus Fischer
- AG Systematics and Evolutionary Biology, IBU-Faculty V, Carl von Ossietzky Universität Oldenburg, Oldenburg, Germany.
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Large-scale transcriptome analysis of retroelements in the migratory locust, Locusta migratoria. PLoS One 2012; 7:e40532. [PMID: 22792363 PMCID: PMC3391268 DOI: 10.1371/journal.pone.0040532] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2011] [Accepted: 06/10/2012] [Indexed: 11/23/2022] Open
Abstract
Background Retroelements can successfully colonize eukaryotic genome through RNA-mediated transposition, and are considered to be some of the major mediators of genome size. The migratory locust Locusta migratoria is an insect with a large genome size, and its genome is probably subject to the proliferation of retroelements. An analysis of deep-sequencing transcriptome data will elucidate the structure, diversity and expression characteristics of retroelements. Results We performed a de novo assembly from deep sequencing RNA-seq data and identified 105 retroelements in the locust transcriptome. Phylogenetic analysis of reverse transcriptase sequences revealed 1 copia, 1 BEL, 8 gypsy and 23 non-long terminal repeat (LTR) retroelements in the locust transcriptome. A novel approach was developed to identify full-length LTR retroelements. A total of 5 full-length LTR retroelements and 2 full-length non-LTR retroelements that contained complete structures for retrotransposition were identified. Structural analysis indicated that all these retroelements may have been activated or deprived of retrotransposition activities very recently. Expression profiling analysis revealed that the retroelements exhibited a unique expression pattern at the egg stage and showed differential expression profiles between the solitarious and gregarious phases at the fifth instar and adult stage. Conclusion We hereby present the first de novo transcriptome analysis of retroelements in a species whose genome is not available. This work contributes to a comprehensive understanding of the landscape of retroelements in the locust transcriptome. More importantly, the results reveal that non-LTR retroelements are abundant and diverse in the locust transcriptome.
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Abstract
A major current molecular evolution challenge is to link comparative genomic patterns to species' biology and ecology. Breeding systems are pivotal because they affect many population genetic processes, and thus genome evolution. We review theoretical predictions and empirical evidence about molecular evolutionary processes under three distinct breeding systems-outcrossing, selfing, and asexuality. Breeding systems may have a profound impact on genome evolution, including molecular evolutionary rates, base composition, genomic conflict, and possibly genome size. However, while asexual species essentially conform to theoretical predictions, the situation is less simple in selfing species. We discuss the possible reasons to potentially explain this paradox. In reverse, comparative and population genomic data and approaches help revisiting old questions on the long-term evolution of breeding systems.
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Kraaijeveld K, Zwanenburg B, Hubert B, Vieira C, De Pater S, Van Alphen JJM, Den Dunnen JT, De Knijff P. Transposon proliferation in an asexual parasitoid. Mol Ecol 2012; 21:3898-906. [PMID: 22548357 DOI: 10.1111/j.1365-294x.2012.5582.x] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
The widespread occurrence of sex is one of the most elusive problems in evolutionary biology. Theory predicts that asexual lineages can be driven to extinction by uncontrolled proliferation of vertically transmitted transposable elements (TEs), which accumulate because of the inefficiency of purifying selection in the absence of sex and recombination. To test this prediction, we compared genome-wide TE load between a sexual lineage of the parasitoid wasp Leptopilina clavipes and a lineage of the same species that is rendered asexual by Wolbachia-induced parthenogenesis. We obtained draft genome sequences at 15-20× coverage of both the sexual and the asexual lineages using next-generation sequencing. We identified transposons of most major classes in both lineages. Quantification of TE abundance using coverage depth showed that copy numbers in the asexual lineage exceeded those in the sexual lineage for DNA transposons, but not LTR and LINE-like elements. However, one or a small number of gypsy-like LTR elements exhibited a fourfold higher coverage in the asexual lineage. Quantitative PCR showed that high loads of this gypsy-like TE were characteristic for 11 genetically distinct asexual wasp lineages when compared to sexual lineages. We found no evidence for an overall increase in copy number for all TE types in asexuals as predicted by theory. Instead, we suggest that the expansions of specific TEs are best explained as side effects of (epi)genetic manipulations of the host genome by Wolbachia. Asexuality is achieved in a myriad of ways in nature, many of which could similarly result in TE proliferation.
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Affiliation(s)
- Ken Kraaijeveld
- Department of Human Genetics, Leiden University Medical Center S4-P, PO Box 9600, 2300 RC Leiden, The Netherlands.
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