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Dayi M. Diversity and evolution of transposable elements in the plant-parasitic nematodes. BMC Genomics 2024; 25:511. [PMID: 38783171 PMCID: PMC11118728 DOI: 10.1186/s12864-024-10435-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Accepted: 05/21/2024] [Indexed: 05/25/2024] Open
Abstract
BACKGROUND Transposable elements (TEs) are mobile DNA sequences that propagate within genomes, occupying a significant portion of eukaryotic genomes and serving as a source of genetic variation and innovation. TEs can impact genome dynamics through their repetitive nature and mobility. Nematodes are incredibly versatile organisms, capable of thriving in a wide range of environments. The plant-parasitic nematodes are able to infect nearly all vascular plants, leading to significant crop losses and management expenses worldwide. It is worth noting that plant parasitism has evolved independently at least three times within this nematode group. Furthermore, the genome size of plant-parasitic nematodes can vary substantially, spanning from 41.5 Mbp to 235 Mbp. To investigate genome size variation and evolution in plant-parasitic nematodes, TE composition, diversity, and evolution were analysed in 26 plant-parasitic nematodes from 9 distinct genera in Clade IV. RESULTS Interestingly, despite certain species lacking specific types of DNA transposons or retrotransposon superfamilies, they still exhibit a diverse range of TE content. Identification of species-specific TE repertoire in nematode genomes provides a deeper understanding of genome evolution in plant-parasitic nematodes. An intriguing observation is that plant-parasitic nematodes possess extensive DNA transposons and retrotransposon insertions, including recent sightings of LTR/Gypsy and LTR/Pao superfamilies. Among them, the Gypsy superfamilies were found to encode Aspartic proteases in the plant-parasitic nematodes. CONCLUSIONS The study of the transposable element (TE) composition in plant-parasitic nematodes has yielded insightful discoveries. The findings revealed that certain species exhibit lineage-specific variations in their TE makeup. Discovering the species-specific TE repertoire in nematode genomes is a crucial element in understanding the evolution of genomes in plant-parasitic nematodes. It allows us to gain a deeper insight into the intricate workings of these organisms and their genetic makeup. With this knowledge, we are gaining a fundamental piece in the puzzle of understanding the evolution of these parasites. Moreover, recent transpositions have led to the acquisition of new TE superfamilies, especially Gypsy and Pao retrotransposons, further expanding the diversity of TEs in these nematodes. Significantly, the widely distributed Gypsy superfamily possesses proteases that are exclusively associated with parasitism during nematode-host interactions. These discoveries provide a deeper understanding of the TE landscape within plant-parasitic nematodes.
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Affiliation(s)
- Mehmet Dayi
- Forestry Vocational School, Düzce University, Konuralp Campus, 81620, Düzce, Türkiye.
- Faculty of Medicine, University of Miyazaki, Miyazaki, Japan.
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, Chiba, 277-8562, Japan.
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Noronha RCR, Almeida BRR, Chagas MCS, Tavares FS, Cardoso AL, Bastos CEMC, Silva NKN, Klautau AGCM, Luna FO, Attademo FLN, Lima DS, Sabioni LA, Sampaio MIC, Oliveira JM, do Nascimento LAS, Martins C, Vicari MR, Nagamachi CY, Pieczarka JC. Karyotypes of Manatees: New Insights into Hybrid Formation ( Trichechus inunguis × Trichechus m. manatus) in the Amazon Estuary. Genes (Basel) 2022; 13:1263. [PMID: 35886048 PMCID: PMC9323068 DOI: 10.3390/genes13071263] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/11/2022] [Accepted: 07/14/2022] [Indexed: 02/01/2023] Open
Abstract
Great efforts have been made to preserve manatees. Recently, a hybrid zone was described between Trichechus inunguis (TIN) and the Trichechus manatus manatus (TMM) in the Amazon estuary. Cytogenetic data on these sirenians are limited, despite being fundamental to understanding the hybridization/introgression dynamics and genomic organization in Trichechus. We analyzed the karyotype of TMM, TIN, and two hybrid specimens ("Poque" and "Vitor") by classical and molecular cytogenetics. G-band analysis revealed that TMM (2n = 48) and TIN (2n = 56) diverge by at least six Robertsonian translocations and a pericentric inversion. Hybrids had 2n = 50, however, with Autosomal Fundamental Number (FNA) = 88 in "Poque" and FNA = 74 in "Vitor", and chromosomal distinct pairs in heterozygous; additionally, "Vitor" exhibited heteromorphisms and chromosomes whose pairs could not be determined. The U2 snDNA and Histone H3 multi genes are distributed in small clusters along TIN and TMM chromosomes and have transposable Keno and Helitron elements (TEs) in their sequences. The different karyotypes observed among manatee hybrids may indicate that they represent different generations formed by crossing between fertile hybrids and TIN. On the other hand, it is also possible that all hybrids recorded represent F1 and the observed karyotype differences must result from mechanisms of elimination.
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Affiliation(s)
- Renata C. R. Noronha
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
| | - Bruno R. R. Almeida
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
- Campus Itaituba, Instituto Federal de Educação, Ciência e Tecnologia do Pará, Itaituba 68183-300, PA, Brazil
| | - Monique C. S. Chagas
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
| | - Flávia S. Tavares
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
| | - Adauto L. Cardoso
- Laboratório Genômica Integrativa, Departamento de Biologia Estrutural e Funcional, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu 18618-970, SP, Brazil; (A.L.C.); (C.M.)
| | - Carlos E. M. C. Bastos
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
| | - Natalia K. N. Silva
- Campus Tucuruí, Universidade do Estado do Pará, Tucuruí 68455-210, PA, Brazil;
| | - Alex G. C. M. Klautau
- Centro Nacional de Pesquisa e Conservação da Biodiversidade Marinha do Norte, Instituto Chico Mendes de Conservação da Biodiversidade, Belém 66635-110, PA, Brazil;
| | - Fábia O. Luna
- Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos, Instituto Chico Mendes de Conservação de Biodiversidade, Santos 11050-031, SP, Brazil; (F.O.L.); (F.L.N.A.)
| | - Fernanda L. N. Attademo
- Centro Nacional de Pesquisa e Conservação de Mamíferos Aquáticos, Instituto Chico Mendes de Conservação de Biodiversidade, Santos 11050-031, SP, Brazil; (F.O.L.); (F.L.N.A.)
- Departamento de Zoologia, Programa de Pós-Graduação em Biologia Animal/PPBA, Laboratório de Ecologia Comportamento e Conservação/LECC, Universidade Federal de Pernambuco/UFPE, Recife 50670-901, PE, Brazil
| | - Danielle S. Lima
- Grupo de Pesquisa em Mamíferos Aquáticos Amazônicos, Instituto de Desenvolvimento Sustentável Mamirauá, Estrada do Bexiga, Tefé 69553-225, AM, Brazil; (D.S.L.); (L.A.S.)
- Rede de Pesquisa e Conservação de Sirênios no Estuário Amazônico, Macapá 68903-197, AP, Brazil
| | - Luiz A. Sabioni
- Grupo de Pesquisa em Mamíferos Aquáticos Amazônicos, Instituto de Desenvolvimento Sustentável Mamirauá, Estrada do Bexiga, Tefé 69553-225, AM, Brazil; (D.S.L.); (L.A.S.)
- Rede de Pesquisa e Conservação de Sirênios no Estuário Amazônico, Macapá 68903-197, AP, Brazil
- Campus Porto Grande, Instituto Federal de Educação Ciência e Tecnologia do Amapá, Rodovia BR 210, Km 103, s/n, Zona Rural, Porto Grande 68997-000, AP, Brazil
| | - Maria I. C. Sampaio
- Instituto de Estudos Costeiros, Campus Bragança, Universidade Federal do Pará, Bragança 68600-000, PA, Brazil;
| | - Jairo Moura Oliveira
- Zoological Park of Santarém, ZOOUNAMA, Universidade da Amazônia, Santarém 68030-150, PA, Brazil;
| | | | - Cesar Martins
- Laboratório Genômica Integrativa, Departamento de Biologia Estrutural e Funcional, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu 18618-970, SP, Brazil; (A.L.C.); (C.M.)
| | - Marcelo R. Vicari
- Departamento de Biologia Estrutural, Molecular e Genética, Universidade Estadual de Ponta Grossa, Ponta Grossa 84030-900, PR, Brazil;
| | - Cleusa Y. Nagamachi
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
| | - Julio C. Pieczarka
- Laboratório de Citogenética, Centro de Estudos Avançados da Biodiversidade, Instituto de Ciências Biológicas, Universidade Federal do Pará, Belém 66075-110, PA, Brazil; (B.R.R.A.); (M.C.S.C.); (F.S.T.); (C.E.M.C.B.); (C.Y.N.); (J.C.P.)
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A prototype of the mammalian sulfotransferase 1 (SULT1) family in Xenopus laevis: Characterization of a biased usage of SULT1 genes located in the S-subgenome. Gene 2022; 830:146495. [PMID: 35447235 DOI: 10.1016/j.gene.2022.146495] [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: 12/26/2021] [Revised: 03/29/2022] [Accepted: 04/14/2022] [Indexed: 11/04/2022]
Abstract
BLAST searches previously carried out against Xenopus genome databases, using the cloned X. laevis cytosolic sulfotransferase 1 (SULT1) cDNA sequence, revealed the presence of more than a dozen members of this gene family. Among them, 11 genes composed of five sets, four pairs and a triplet, were homeologous genes in the X. laevis allotetraploid genome consisting of S- and L-subgenomes (≥83% identity within a set). Phylogenetic and synteny analyses of tetrapod SULT1 genes demonstrated that X. laevis possessed six subfamilies, four of which were related to mammalian SULT1 gene subfamilies, while two were ectothermic vertebrate-specific and amphibian-specific SULT1 gene subfamilies. Five sets of homeologous SULT1 genes were located as a gene cluster, and showed S-subgenome-biased gene expression patterns. Acetylation levels of histone H3 at lysine 9 and H4 were also higher in the homeologous SULT1 genes on the S-subgenome than those on the L-subgenome, however, methylation levels of histone H3 at lysine 9 and DNA methylation levels showed no correlation with their transcript levels. In conclusion, histone modifications such as acetylation may be a key factor that controls the S-subgenome-biased expression of the homeologous SULT1 genes.
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5
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Jaron KS, Bast J, Nowell RW, Ranallo-Benavidez TR, Robinson-Rechavi M, Schwander T. Genomic Features of Parthenogenetic Animals. J Hered 2021; 112:19-33. [PMID: 32985658 PMCID: PMC7953838 DOI: 10.1093/jhered/esaa031] [Citation(s) in RCA: 35] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2020] [Accepted: 08/17/2020] [Indexed: 12/21/2022] Open
Abstract
Evolution without sex is predicted to impact genomes in numerous ways. Case studies of individual parthenogenetic animals have reported peculiar genomic features that were suggested to be caused by their mode of reproduction, including high heterozygosity, a high abundance of horizontally acquired genes, a low transposable element load, or the presence of palindromes. We systematically characterized these genomic features in published genomes of 26 parthenogenetic animals representing at least 18 independent transitions to asexuality. Surprisingly, not a single feature was systematically replicated across a majority of these transitions, suggesting that previously reported patterns were lineage-specific rather than illustrating the general consequences of parthenogenesis. We found that only parthenogens of hybrid origin were characterized by high heterozygosity levels. Parthenogens that were not of hybrid origin appeared to be largely homozygous, independent of the cellular mechanism underlying parthenogenesis. Overall, despite the importance of recombination rate variation for the evolution of sexual animal genomes, the genome-wide absence of recombination does not appear to have had the dramatic effects which are expected from classical theoretical models. The reasons for this are probably a combination of lineage-specific patterns, the impact of the origin of parthenogenesis, and a survivorship bias of parthenogenetic lineages.
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Affiliation(s)
- Kamil S Jaron
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Jens Bast
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
| | - Reuben W Nowell
- Department of Life Sciences, Imperial College London, Ascot, Berkshire, UK
- Reuben W. Nowell is now at the Department of Zoology, University of Oxford, Oxford, UK
| | | | - Marc Robinson-Rechavi
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
- Swiss Institute of Bioinformatics, Lausanne, Switzerland
| | - Tanja Schwander
- Department of Ecology and Evolution, University of Lausanne, Lausanne, Switzerland
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6
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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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Dalziel AC, Tirbhowan S, Drapeau HF, Power C, Jonah LS, Gbotsyo YA, Dion‐Côté A. Using asexual vertebrates to study genome evolution and animal physiology: Banded ( Fundulus diaphanus) x Common Killifish ( F. heteroclitus) hybrid lineages as a model system. Evol Appl 2020; 13:1214-1239. [PMID: 32684956 PMCID: PMC7359844 DOI: 10.1111/eva.12975] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2019] [Revised: 03/12/2020] [Accepted: 03/16/2020] [Indexed: 12/27/2022] Open
Abstract
Wild, asexual, vertebrate hybrids have many characteristics that make them good model systems for studying how genomes evolve and epigenetic modifications influence animal physiology. In particular, the formation of asexual hybrid lineages is a form of reproductive incompatibility, but we know little about the genetic and genomic mechanisms by which this mode of reproductive isolation proceeds in animals. Asexual lineages also provide researchers with the ability to produce genetically identical individuals, enabling the study of autonomous epigenetic modifications without the confounds of genetic variation. Here, we briefly review the cellular and molecular mechanisms leading to asexual reproduction in vertebrates and the known genetic and epigenetic consequences of the loss of sex. We then specifically discuss what is known about asexual lineages of Fundulus diaphanus x F. heteroclitus to highlight gaps in our knowledge of the biology of these clones. Our preliminary studies of F. diaphanus and F. heteroclitus karyotypes from Porter's Lake (Nova Scotia, Canada) agree with data from other populations, suggesting a conserved interspecific chromosomal arrangement. In addition, genetic analyses suggest that: (a) the same major clonal lineage (Clone A) of F. diaphanus x F. heteroclitus has remained dominant over the past decade, (b) some minor clones have also persisted, (c) new clones may have recently formed, and iv) wild clones still mainly descend from F. diaphanus ♀ x F. heteroclitus ♂ crosses (96% in 2017-2018). These data suggest that clone formation may be a relatively rare, but continuous process, and there are persistent environmental or genetic factors causing a bias in cross direction. We end by describing our current research on the genomic causes and consequences of a transition to asexuality and the potential physiological consequences of epigenetic variation.
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Affiliation(s)
| | - Svetlana Tirbhowan
- Department of BiologySaint Mary's UniversityHalifaxNSCanada
- Département de biologieUniversité de MonctonMonctonNBCanada
| | | | - Claude Power
- Département de biologieUniversité de MonctonMonctonNBCanada
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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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Shao GM, Li XY, Wang Y, Wang ZW, Li Z, Zhang XJ, Zhou L, Gui JF. Whole Genome Incorporation and Epigenetic Stability in a Newly Synthetic Allopolyploid of Gynogenetic Gibel Carp. Genome Biol Evol 2018; 10:2394-2407. [PMID: 30085110 PMCID: PMC6143163 DOI: 10.1093/gbe/evy165] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/01/2018] [Indexed: 12/23/2022] Open
Abstract
Allopolyploidization plays an important role in speciation, and some natural or synthetic allopolyploid fishes have been extensively applied to aquaculture. Although genetic and epigenetic inheritance and variation associated with plant allopolyploids have been well documented, the relative research in allopolyploid animals is scarce. In this study, the genome constitution and DNA methylation inheritance in a newly synthetic allopolyploid of gynogenetic gibel carp were analyzed. The incorporation of a whole genome of paternal common carp sperm in the allopolyploid was confirmed by genomic in situ hybridization, chromosome localization of 45S rDNAs, and sequence comparison. Pooled sample-based methylation sensitive amplified polymorphism (MSAP) revealed that an overwhelming majority (98.82%) of cytosine methylation patterns in the allopolyploid were inherited from its parents of hexaploid gibel carp clone D and common carp. Compared to its parents, 11 DNA fragments in the allopolyploid were proved to be caused by interindividual variation, recombination, deletion, and mutation through individual sample-based MSAP and sequencing. Contrast to the rapid and remarkable epigenetic changes in most of analyzed neopolyploids, no cytosine methylation variation was detected in the gynogenetic allopolyploid. Therefore, the newly synthetic allopolyploid of gynogenetic gibel carp combined genomes from its parents and maintained genetic and epigenetic stability after its formation and subsequently seven successive gynogenetic generations. Our current results provide a paradigm for recurrent polyploidy consequences in the gynogenetic allopolyploid animals.
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Affiliation(s)
- Guang-Ming Shao
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Xi-Yin Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yang Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhong-Wei Wang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Zhi Li
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Xiao-Juan Zhang
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
| | - Li Zhou
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jian-Fang Gui
- State Key Laboratory of Freshwater Ecology and Biotechnology, Institute of Hydrobiology, Chinese Academy of Sciences, Wuhan, China
- University of Chinese Academy of Sciences, Beijing, China
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Rodriguez F, Arkhipova IR. Transposable elements and polyploid evolution in animals. Curr Opin Genet Dev 2018; 49:115-123. [PMID: 29715568 DOI: 10.1016/j.gde.2018.04.003] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2017] [Revised: 03/08/2018] [Accepted: 04/11/2018] [Indexed: 01/07/2023]
Abstract
Polyploidy in animals is much less common than in plants, where it is thought to be pervasive in all higher plant lineages. Recent studies have highlighted the impact of polyploidization and the associated process of diploidy restoration on the evolution and speciation of selected taxonomic groups in the animal kingdom: from vertebrates represented by salmonid fishes and African clawed frogs to invertebrates represented by parasitic root-knot nematodes and bdelloid rotifers. In this review, we focus on the unique and diverse roles that transposable elements may play in these processes, from marking and diversifying subgenome-specific chromosome sets before hybridization, to influencing genome restructuring during rediploidization, to affecting subgenome-specific regulatory evolution, and occasionally providing opportunities for domestication and gene amplification to restore and improve functionality. There is still much to be learned from the future comparative genomic studies of chromosome-sized and haplotype-aware assemblies, and from postgenomic studies elucidating genetic and epigenetic regulatory phenomena across short and long evolutionary distances in the metazoan tree of life.
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Affiliation(s)
- Fernando Rodriguez
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA
| | - Irina R Arkhipova
- Josephine Bay Paul Center for Comparative Molecular Biology and Evolution, Marine Biological Laboratory, Woods Hole, MA 02543, USA.
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Chalopin D, Volff JN. Analysis of the spotted gar genome suggests absence of causative link between ancestral genome duplication and transposable element diversification in teleost fish. JOURNAL OF EXPERIMENTAL ZOOLOGY PART B-MOLECULAR AND DEVELOPMENTAL EVOLUTION 2017; 328:629-637. [PMID: 28921831 DOI: 10.1002/jez.b.22761] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/02/2017] [Revised: 07/18/2017] [Accepted: 07/19/2017] [Indexed: 11/08/2022]
Abstract
Teleost fish have been shown to contain many superfamilies of transposable elements (TEs) that are absent from most tetrapod genomes. Since theories predict an increase in TE activity following polyploidization, such diversity might be linked to the 3R whole-genome duplication that occurred approximately 300 million years ago before the teleost radiation. To test this hypothesis, we have analyzed the genome of the spotted gar Lepisosteus oculatus, which diverged from the teleost lineage before the 3R duplication. Our results indicate that TE diversity and copy numbers are similar in gar and teleost genomes, suggesting that TE diversity was ancestral and not linked to the 3R whole-genome duplication. We propose that about 25 distinct superfamilies of TEs were present in the last ancestor of gars and teleost fish about 300 million years ago in the ray-finned fish lineage.
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Affiliation(s)
- Domitille Chalopin
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, UMR5242 CNRS, Université Claude Bernard Lyon I, Lyon, France
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon, UMR5242 CNRS, Université Claude Bernard Lyon I, Lyon, France
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Kamneva OK, Syring J, Liston A, Rosenberg NA. Evaluating allopolyploid origins in strawberries (Fragaria) using haplotypes generated from target capture sequencing. BMC Evol Biol 2017; 17:180. [PMID: 28778145 PMCID: PMC5543553 DOI: 10.1186/s12862-017-1019-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2017] [Accepted: 07/25/2017] [Indexed: 12/30/2022] Open
Abstract
BACKGROUND Hybridization is observed in many eukaryotic lineages and can lead to the formation of polyploid species. The study of hybridization and polyploidization faces challenges both in data generation and in accounting for population-level phenomena such as coalescence processes in phylogenetic analysis. Genus Fragaria is one example of a set of plant taxa in which a range of ploidy levels is observed across species, but phylogenetic origins are unknown. RESULTS Here, using 20 diploid and polyploid Fragaria species, we combine approaches from NGS data analysis and phylogenetics to infer evolutionary origins of polyploid strawberries, taking into account coalescence processes. We generate haplotype sequences for 257 low-copy nuclear markers assembled from Illumina target capture sequence data. We then identify putative hybridization events by analyzing gene tree topologies, and further test predicted hybridizations in a coalescence framework. This approach confirms the allopolyploid ancestry of F. chiloensis and F. virginiana, and provides new allopolyploid ancestry hypotheses for F. iturupensis, F. moschata, and F. orientalis. Evidence of gene flow between diploids F. bucharica and F. vesca is also detected, suggesting that it might be appropriate to consider these groups as conspecifics. CONCLUSIONS This study is one of the first in which target capture sequencing followed by computational deconvolution of individual haplotypes is used for tracing origins of polyploid taxa. The study also provides new perspectives on the evolutionary history of Fragaria.
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Affiliation(s)
- Olga K Kamneva
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305, USA.
| | - John Syring
- Department of Biology, Linfield College, McMinnville, OR, 97128, USA
| | - Aaron Liston
- Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR, 97331, USA
| | - Noah A Rosenberg
- Department of Biology, Stanford University, 371 Serra Mall, Stanford, CA, 94305, USA
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Identification of misexpressed genetic elements in hybrids between Drosophila-related species. Sci Rep 2017; 7:40618. [PMID: 28091568 PMCID: PMC5238404 DOI: 10.1038/srep40618] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 12/09/2016] [Indexed: 12/30/2022] Open
Abstract
Crosses between close species can lead to genomic disorders, often considered to be the cause of hybrid incompatibility, one of the initial steps in the speciation process. How these incompatibilities are established and what are their causes remain unclear. To understand the initiation of hybrid incompatibility, we performed reciprocal crosses between two species of Drosophila (D. mojavensis and D. arizonae) that diverged less than 1 Mya. We performed a genome-wide transcriptomic analysis on ovaries from parental lines and on hybrids from reciprocal crosses. Using an innovative procedure of co-assembling transcriptomes, we show that parental lines differ in the expression of their genes and transposable elements. Reciprocal hybrids presented specific gene categories and few transposable element families misexpressed relative to the parental lines. Because TEs are mainly silenced by piwi-interacting RNAs (piRNAs), we hypothesize that in hybrids the deregulation of specific TE families is due to the absence of such small RNAs. Small RNA sequencing confirmed our hypothesis and we therefore propose that TEs can indeed be major players of genome differentiation and be implicated in the first steps of genomic incompatibilities through small RNA regulation.
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Ribeiro LB, Moraes Neto A, Artoni RF, Matoso DA, Feldberg E. Chromosomal Mapping of Repetitive Sequences (Rex3, Rex6, and rDNA Genes) in Hybrids Between Colossoma macropomum (Cuvier, 1818) and Piaractus mesopotamicus (Holmberg, 1887). Zebrafish 2017; 14:155-160. [PMID: 28067606 DOI: 10.1089/zeb.2016.1378] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Some species of Characiformes are known for their high economic value, such as Colossoma macropomum and Piaractus mesopotamicus, and are used in aquaculture programs to generate hybrid tambacu (interbreeding of C. macropomum females and P. mesopotamicus males). The present work aimed to investigate the location of the Rex3 and Rex6 transposable elements in the hybrid and in the species, in addition to checking the genomic organization of the 18S and 5S rDNA in tambacu. The diploid number found for the hybrid was equal to 54 chromosomes, with heterochromatic blocks distributed mainly in the centromeric portions. The chromosomal location of the mobile elements Rex3 and Rex6 in C. macropomum, P. mesopotamicus, and in the hybrid between these species enabled knowledge expansion and the generation of data on such mobile elements. In addition, the location of such elements is not related to the distribution of ribosomal DNA sites. The mapping of the 18S rDNA was shown to be effective in cytogenetic identification of the hybrid tambacu, allowing for differentiation from the parent species and from the hybrid between C. macropomum and the other species from Piaractus (P. brachypomus).
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Affiliation(s)
- Leila Braga Ribeiro
- 1 Centro de Ciências da Saúde, Universidade Federal de Roraima (UFRR) , Boa Vista, Brazil
| | - Americo Moraes Neto
- 2 Programa de Pós-Graduação em Ciência Animal, Faculdade de Medicina Veterinária e Zootecnia, Universidade Federal de Mato Grosso do Sul (UFMS) , Campo Grande, Brazil
| | - Roberto Ferreira Artoni
- 3 Programa de Pós-Graduação em Biologia Evolutiva, Departamento de Biologia Estrutural, Molecular e Genética, Universidade Estadual de Ponta Grossa (UEPG) , Ponta Grossa, Brazil
| | | | - Eliana Feldberg
- 5 Coordenação de Biodiversidade, Instituto Nacional de Pesquisas da Amazônia (INPA) , Manaus, Brazil
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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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Dynamics of Rex3 in the genomes of endangered Iberian Leuciscinae (Teleostei, Cyprinidae) and their natural hybrids. Mol Cytogenet 2015; 8:81. [PMID: 26512297 PMCID: PMC4623273 DOI: 10.1186/s13039-015-0180-1] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2015] [Accepted: 10/01/2015] [Indexed: 02/08/2023] Open
Abstract
Background Iberian Leuciscinae are greatly diverse comprising taxa of hybrid origin. With highly conservative karyotypes, Iberian Chondrostoma s.l. have recently demonstrated sub-chromosomal differentiation and rapid genome restructuring in natural hybrids, which was confirmed by ribosomal DNA (rDNA) transposition and/or multiplication. To understand the role of repetitive DNAs in the differentiation of their genomes, a genetic and molecular cytogenetic survey was conducted in Achondrostoma oligolepis, Anaecypris hispanica, Iberochondrostoma lemmingii, I. lusitanicum, Pseudochondrostoma duriense, P. polylepis, Squalius pyrenaicus and hybrids between A. oligolepis x (P. duriense/P. polylepis), representing ‘alburnine’, chondrostomine and Squalius lineages. Results Partial Rex3 sequences evidenced high sequence homology among Leuciscinae (≥98 %) and different fish families (80–95 %) proposing a relatively recent activity of these elements in the species inspected. Low nucleotide substitution rates (<20 %) and intact ORFs suggests that Rex3 may in fact be active in these genomes. The chromosomal distribution of Rex3 retroelement was found highly concentrated at pericentromeric and moderately at subtelomeric blocks, co-localizing with 5S rDNA loci, and correlating with blocks of heterochromatin and C0t-1 DNA. This accumulation was evident in at least 10 chromosome pairs, a pattern that seemed to be shared among the different species, likely pre-dating their divergence. Nevertheless, species-specific clusters were detected in I. lusitanicum, P. duriense, P. polylepis and S. pyrenaicus demonstrating rapid and independent differentiation. Natural hybrids followed the same patterns of accumulation and association with repetitive sequences. An increased number of Rex3 clusters now associating also with translocated 45S rDNA clusters vouched for other genomic rearrangements in hybrids. Rex3 sequence phylogeny did not agree with its hosts’ phylogeny but the observed distribution pattern is congruent with an evolutionary tendency to protect its activity, a robust regulatory system and/or events of horizontal transfer. Conclusions This is the first report directed at retroelement physical mapping in Cyprinidae. It helped outlining conceivable ancestral homologies and recognizing retrotransposon activation in hybrids, being possibly associated with genome diversification within the subfamily. The extensive diversity of Iberian Leuciscinae makes them excellent candidates to explore the processes and mechanisms behind the great plasticity distinguishing vertebrate genomes. Electronic supplementary material The online version of this article (doi:10.1186/s13039-015-0180-1) contains supplementary material, which is available to authorized users.
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Martoni F, Eickbush DG, Scavariello C, Luchetti A, Mantovani B. Dead element replicating: degenerate R2 element replication and rDNA genomic turnover in the Bacillus rossius stick insect (Insecta: Phasmida). PLoS One 2015; 10:e0121831. [PMID: 25799008 PMCID: PMC4370867 DOI: 10.1371/journal.pone.0121831] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2014] [Accepted: 02/04/2015] [Indexed: 11/18/2022] Open
Abstract
R2 is an extensively investigated non-LTR retrotransposon that specifically inserts into the 28S rRNA gene sequences of a wide range of metazoans, disrupting its functionality. During R2 integration, first strand synthesis can be incomplete so that 5’ end deleted copies are occasionally inserted. While active R2 copies repopulate the locus by retrotransposing, the non-functional truncated elements should frequently be eliminated by molecular drive processes leading to the concerted evolution of the rDNA array(s). Although, multiple R2 lineages have been discovered in the genome of many animals, the rDNA of the stick insect Bacillus rossius exhibits a peculiar situation: it harbors both a canonical, functional R2 element (R2Brfun) as well as a full-length but degenerate element (R2Brdeg). An intensive sequencing survey in the present study reveals that all truncated variants in stick insects are present in multiple copies suggesting they were duplicated by unequal recombination. Sequencing results also demonstrate that all R2Brdeg copies are full-length, i. e. they have no associated 5' end deletions, and functional assays indicate they have lost the active ribozyme necessary for R2 RNA maturation. Although it cannot be completely ruled out, it seems unlikely that the degenerate elements replicate via reverse transcription, exploiting the R2Brfun element enzymatic machinery, but rather via genomic amplification of inserted 28S by unequal recombination. That inactive copies (both R2Brdeg or 5'-truncated elements) are not eliminated in a short term in stick insects contrasts with findings for the Drosophila R2, suggesting a widely different management of rDNA loci and a lower efficiency of the molecular drive while achieving the concerted evolution.
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Affiliation(s)
- Francesco Martoni
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
| | - Danna G. Eickbush
- Department of Biology, University of Rochester, Rochester, New York, United States of America
| | - Claudia Scavariello
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
| | - Andrea Luchetti
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
- * E-mail:
| | - Barbara Mantovani
- Dipartimento di Scienze Biologiche, Geologiche e Ambientali, Università di Bologna, Bologna, Italy
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Sytnikova YA, Rahman R, Chirn GW, Clark JP, Lau NC. Transposable element dynamics and PIWI regulation impacts lncRNA and gene expression diversity in Drosophila ovarian cell cultures. Genome Res 2014; 24:1977-90. [PMID: 25267525 PMCID: PMC4248314 DOI: 10.1101/gr.178129.114] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Piwi proteins and Piwi-interacting RNAs (piRNAs) repress transposable elements (TEs) from mobilizing in gonadal cells. To determine the spectrum of piRNA-regulated targets that may extend beyond TEs, we conducted a genome-wide survey for transcripts associated with PIWI and for transcripts affected by PIWI knockdown in Drosophila ovarian somatic sheet (OSS) cells, a follicle cell line expressing the Piwi pathway. Despite the immense sequence diversity among OSS cell piRNAs, our analysis indicates that TE transcripts are the major transcripts associated with and directly regulated by PIWI. However, several coding genes were indirectly regulated by PIWI via an adjacent de novo TE insertion that generated a nascent TE transcript. Interestingly, we noticed that PIWI-regulated genes in OSS cells greatly differed from genes affected in a related follicle cell culture, ovarian somatic cells (OSCs). Therefore, we characterized the distinct genomic TE insertions across four OSS and OSC lines and discovered dynamic TE landscapes in gonadal cultures that were defined by a subset of active TEs. Particular de novo TEs appeared to stimulate the expression of novel candidate long noncoding RNAs (lncRNAs) in a cell lineage-specific manner, and some of these TE-associated lncRNAs were associated with PIWI and overlapped PIWI-regulated genes. Our analyses of OSCs and OSS cells demonstrate that despite having a Piwi pathway to suppress endogenous mobile elements, gonadal cell TE landscapes can still dramatically change and create transcriptome diversity.
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Affiliation(s)
- Yuliya A Sytnikova
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Reazur Rahman
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Gung-Wei Chirn
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Josef P Clark
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
| | - Nelson C Lau
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, Massachusetts 02454, USA
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Shapiro JA. Epigenetic control of mobile DNA as an interface between experience and genome change. Front Genet 2014; 5:87. [PMID: 24795749 PMCID: PMC4007016 DOI: 10.3389/fgene.2014.00087] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2014] [Accepted: 04/01/2014] [Indexed: 12/29/2022] Open
Abstract
Mobile DNA in the genome is subject to RNA-targeted epigenetic control. This control regulates the activity of transposons, retrotransposons and genomic proviruses. Many different life history experiences alter the activities of mobile DNA and the expression of genetic loci regulated by nearby insertions. The same experiences induce alterations in epigenetic formatting and lead to trans-generational modifications of genome expression and stability. These observations lead to the hypothesis that epigenetic formatting directed by non-coding RNA provides a molecular interface between life history events and genome alteration.
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Affiliation(s)
- James A. Shapiro
- Department of Biochemistry and Molecular Biology, University of ChicagoChicago, IL, USA
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20
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Vergilino R, Eagle SH, Crease TJ, Dufresne F. Impact of ploidy level on the distribution of Pokey element insertions in the Daphnia pulex complex. Mob DNA 2014; 5:1. [PMID: 24382139 PMCID: PMC3882798 DOI: 10.1186/1759-8753-5-1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2013] [Accepted: 11/20/2013] [Indexed: 11/22/2022] Open
Abstract
Background Transposable elements (TEs) play a major role in genome evolution. Their capacity to move and/or multiply in the genome of their host may have profound impacts on phenotypes and dramatic consequences on genome structure. The population dynamics and distribution of TEs are influenced by their mode of transposition, the availability of niches in host genomes, and host population dynamics. Theories predict an increase in the number of TE insertions following hybridization or polyploidization. Evolution of TEs in hybrids and polyploids has mostly been studied in plants; few studies have examined the impacts of hybridization and/or polyploidization on TEs in animals. Hybrids and polyploids have arisen multiple times in the Daphnia pulex complex and are thought to reproduce by obligate parthenogenesis. Our study examines the effects of ploidy level on polymorphism and number of Pokey element insertions in diploid and polyploid hybrid isolates from the Daphnia pulex complex. Results The polymorphism of Pokey insertion sites did not depend solely on either the ploidy level or the genetic background of their host; therefore, it may be the result of interactions between these parameters and other parameters such as Pokey activity, selection and/or drift. No significant effect of ploidy level was found on the number of Pokey insertions using TE display and qPCR. However, the load of Pokey insertion sites and the number of unique insertion sites were slightly (but not significantly) higher in polyploids than in diploids. Conclusions These results suggest a lack of increase in the number of Pokey insertions following polyploidization but higher availability of Pokey insertion sites in polyploids than in diploids. Compared to previous TE display and qPCR results, the load of Pokey insertions in hybrid diploids was higher than in non-hybrid sexual and asexual diploids, which suggests an increase in the density of Pokey insertions following hybridization.
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Affiliation(s)
- Roland Vergilino
- Département de Biologie, Chimie et Géographie, Université du Québec à Rimouski, Rimouski, Québec G5L 3A1, Canada.
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