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Wei KHC, Mai D, Chatla K, Bachtrog D. Dynamics and Impacts of Transposable Element Proliferation in the Drosophila nasuta Species Group Radiation. Mol Biol Evol 2022; 39:msac080. [PMID: 35485457 PMCID: PMC9075770 DOI: 10.1093/molbev/msac080] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Transposable element (TE) mobilization is a constant threat to genome integrity. Eukaryotic organisms have evolved robust defensive mechanisms to suppress their activity, yet TEs can escape suppression and proliferate, creating strong selective pressure for host defense to adapt. This genomic conflict fuels a never-ending arms race that drives the rapid evolution of TEs and recurrent positive selection of genes involved in host defense; the latter has been shown to contribute to postzygotic hybrid incompatibility. However, how TE proliferation impacts genome and regulatory divergence remains poorly understood. Here, we report the highly complete and contiguous (N50 = 33.8-38.0 Mb) genome assemblies of seven closely related Drosophila species that belong to the nasuta species group-a poorly studied group of flies that radiated in the last 2 My. We constructed a high-quality de novo TE library and gathered germline RNA-seq data, which allowed us to comprehensively annotate and compare TE insertion patterns between the species, and infer the evolutionary forces controlling their spread. We find a strong negative association between TE insertion frequency and expression of genes nearby; this likely reflects survivor bias from reduced fitness impact of TEs inserting near lowly expressed, nonessential genes, with limited TE-induced epigenetic silencing. Phylogenetic analyses of insertions of 147 TE families reveal that 53% of them show recent amplification in at least one species. The most highly amplified TE is a nonautonomous DNA element (Drosophila INterspersed Element; DINE) which has gone through multiple bouts of expansions with thousands of full-length copies littered throughout each genome. Across all TEs, we find that TEs expansions are significantly associated with high expression in the expanded species consistent with suppression escape. Thus, whereas horizontal transfer followed by the invasion of a naïve genome has been highlighted to explain the long-term survival of TEs, our analysis suggests that evasion of host suppression of resident TEs is a major strategy to persist over evolutionary times. Altogether, our results shed light on the heterogenous and context-dependent nature in which TEs affect gene regulation and the dynamics of rampant TE proliferation amidst a recently radiated species group.
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Affiliation(s)
- Kevin H.-C. Wei
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Dat Mai
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Kamalakar Chatla
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
| | - Doris Bachtrog
- Department of Integrative Biology, University of California Berkeley, Berkeley, CA 94720, USA
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Baril T, Hayward A. Migrators within migrators: exploring transposable element dynamics in the monarch butterfly, Danaus plexippus. Mob DNA 2022; 13:5. [PMID: 35172896 PMCID: PMC8848866 DOI: 10.1186/s13100-022-00263-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2021] [Accepted: 02/06/2022] [Indexed: 01/10/2023] Open
Abstract
Background Lepidoptera (butterflies and moths) are an important model system in ecology and evolution. A high-quality chromosomal genome assembly is available for the monarch butterfly (Danaus plexippus), but it lacks an in-depth transposable element (TE) annotation, presenting an opportunity to explore monarch TE dynamics and the impact of TEs on shaping the monarch genome. Results We find 6.21% of the monarch genome is comprised of TEs, a reduction of 6.85% compared to the original TE annotation performed on the draft genome assembly. Monarch TE content is low compared to two closely related species with available genomes, Danaus chrysippus (33.97% TE) and Danaus melanippus (11.87% TE). The biggest TE contributions to genome size in the monarch are LINEs and Penelope-like elements, and three newly identified families, r2-hero_dPle (LINE), penelope-1_dPle (Penelope-like), and hase2-1_dPle (SINE), collectively contribute 34.92% of total TE content. We find evidence of recent TE activity, with two novel Tc1 families rapidly expanding over recent timescales (tc1-1_dPle, tc1-2_dPle). LINE fragments show signatures of genomic deletions indicating a high rate of TE turnover. We investigate associations between TEs and wing colouration and immune genes and identify a three-fold increase in TE content around immune genes compared to other host genes. Conclusions We provide a detailed TE annotation and analysis for the monarch genome, revealing a considerably smaller TE contribution to genome content compared to two closely related Danaus species with available genome assemblies. We identify highly successful novel DNA TE families rapidly expanding over recent timescales, and ongoing signatures of both TE expansion and removal highlight the dynamic nature of repeat content in the monarch genome. Our findings also suggest that insect immune genes are promising candidates for future interrogation of TE-mediated host adaptation. Supplementary Information The online version contains supplementary material available at 10.1186/s13100-022-00263-5.
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Affiliation(s)
- Tobias Baril
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
| | - Alexander Hayward
- Centre for Ecology and Conservation, University of Exeter, Penryn Campus, Penryn, Cornwall, TR10 9FE, UK.
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Abstract
Transposable elements (TEs) are genomic parasites that are found in all genomes, some of which display sequence similarity to certain viruses. In insects, TEs are controlled by the Piwi-interacting small interfering RNA (piRNA) pathway in gonads, while the small interfering RNA (siRNA) pathway is dedicated to TE somatic control and defense against viruses. So far, these two small interfering RNA pathways are considered to involve distinct molecular effectors and are described as independent. Using Sindbis virus (SINV) in Drosophila, here we show that viral infections affect TE transcript amounts via modulations of the piRNA and siRNA repertoires, with the clearest effects in somatic tissues. These results suggest that viral acute or chronic infections may impact TE activity and, thus, the tempo of genetic diversification. In addition, these results deserve further evolutionary considerations regarding potential benefits to the host, the virus, or the TEs.
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Auvinet J, Graça P, Ghigliotti L, Pisano E, Dettaï A, Ozouf-Costaz C, Higuet D. Insertion Hot Spots of DIRS1 Retrotransposon and Chromosomal Diversifications among the Antarctic Teleosts Nototheniidae. Int J Mol Sci 2019; 20:ijms20030701. [PMID: 30736325 PMCID: PMC6387122 DOI: 10.3390/ijms20030701] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 01/30/2019] [Accepted: 02/03/2019] [Indexed: 12/17/2022] Open
Abstract
By their faculty to transpose, transposable elements are known to play a key role in eukaryote genomes, impacting both their structuration and remodeling. Their integration in targeted sites may lead to recombination mechanisms involved in chromosomal rearrangements. The Antarctic fish family Nototheniidae went through several waves of species radiations. It is a suitable model to study transposable element (TE)-mediated mechanisms associated to genome and chromosomal diversifications. After the characterization of Gypsy (GyNoto), Copia (CoNoto), and DIRS1 (YNoto) retrotransposons in the genomes of Nototheniidae (diversity, distribution, conservation), we focused on their chromosome location with an emphasis on the three identified nototheniid radiations (the Trematomus, the plunderfishes, and the icefishes). The strong intrafamily TE conservation and wide distribution across species of the whole family suggest an ancestral acquisition with potential secondary losses in some lineages. GyNoto and CoNoto (including Hydra and GalEa clades) mostly produced interspersed signals along chromosomal arms. On the contrary, insertion hot spots accumulating in localized regions (mainly next to centromeric and pericentromeric regions) highlighted the potential role of YNoto in chromosomal diversifications as facilitator of the fusions which occurred in many nototheniid lineages, but not of the fissions.
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Affiliation(s)
- Juliette Auvinet
- Laboratoire Evolution Paris Seine, Sorbonne Université, CNRS, Univ Antilles, Institut de Biologie Paris Seine (IBPS), F-75005 Paris, France.
| | - Paula Graça
- Laboratoire Evolution Paris Seine, Sorbonne Université, CNRS, Univ Antilles, Institut de Biologie Paris Seine (IBPS), F-75005 Paris, France.
| | - Laura Ghigliotti
- Istituto per lo Studio degli Impatti Antropici e la Sostenibilità in Ambiente Marino (IAS), National Research Council (CNR), 16149 Genoa, Italy.
| | - Eva Pisano
- Istituto per lo Studio degli Impatti Antropici e la Sostenibilità in Ambiente Marino (IAS), National Research Council (CNR), 16149 Genoa, Italy.
| | - Agnès Dettaï
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Museum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, 57, rue Cuvier, 75005 Paris, France.
| | - Catherine Ozouf-Costaz
- Laboratoire Evolution Paris Seine, Sorbonne Université, CNRS, Univ Antilles, Institut de Biologie Paris Seine (IBPS), F-75005 Paris, France.
| | - Dominique Higuet
- Laboratoire Evolution Paris Seine, Sorbonne Université, CNRS, Univ Antilles, Institut de Biologie Paris Seine (IBPS), F-75005 Paris, France.
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Museum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, 57, rue Cuvier, 75005 Paris, France.
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5
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Auvinet J, Graça P, Belkadi L, Petit L, Bonnivard E, Dettaï A, Detrich WH, Ozouf-Costaz C, Higuet D. Mobilization of retrotransposons as a cause of chromosomal diversification and rapid speciation: the case for the Antarctic teleost genus Trematomus. BMC Genomics 2018; 19:339. [PMID: 29739320 PMCID: PMC5941688 DOI: 10.1186/s12864-018-4714-x] [Citation(s) in RCA: 34] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Accepted: 04/23/2018] [Indexed: 11/29/2022] Open
Abstract
Background The importance of transposable elements (TEs) in the genomic remodeling and chromosomal rearrangements that accompany lineage diversification in vertebrates remains the subject of debate. The major impediment to understanding the roles of TEs in genome evolution is the lack of comparative and integrative analyses on complete taxonomic groups. To help overcome this problem, we have focused on the Antarctic teleost genus Trematomus (Notothenioidei: Nototheniidae), as they experienced rapid speciation accompanied by dramatic chromosomal diversity. Here we apply a multi-strategy approach to determine the role of large-scale TE mobilization in chromosomal diversification within Trematomus species. Results Despite the extensive chromosomal rearrangements observed in Trematomus species, our measurements revealed strong interspecific genome size conservation. After identifying the DIRS1, Gypsy and Copia retrotransposon superfamilies in genomes of 13 nototheniid species, we evaluated their diversity, abundance (copy numbers) and chromosomal distribution. Four families of DIRS1, nine of Gypsy, and two of Copia were highly conserved in these genomes; DIRS1 being the most represented within Trematomus genomes. Fluorescence in situ hybridization mapping showed preferential accumulation of DIRS1 in centromeric and pericentromeric regions, both in Trematomus and other nototheniid species, but not in outgroups: species of the Sub-Antarctic notothenioid families Bovichtidae and Eleginopsidae, and the non-notothenioid family Percidae. Conclusions In contrast to the outgroups, High-Antarctic notothenioid species, including the genus Trematomus, were subjected to strong environmental stresses involving repeated bouts of warming above the freezing point of seawater and cooling to sub-zero temperatures on the Antarctic continental shelf during the past 40 millions of years (My). As a consequence of these repetitive environmental changes, including thermal shocks; a breakdown of epigenetic regulation that normally represses TE activity may have led to sequential waves of TE activation within their genomes. The predominance of DIRS1 in Trematomus species, their transposition mechanism, and their strategic location in “hot spots” of insertion on chromosomes are likely to have facilitated nonhomologous recombination, thereby increasing genomic rearrangements. The resulting centric and tandem fusions and fissions would favor the rapid lineage diversification, characteristic of the nototheniid adaptive radiation. Electronic supplementary material The online version of this article (10.1186/s12864-018-4714-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- J Auvinet
- Laboratoire Evolution Paris Seine, Sorbonne Université, Univ Antilles, CNRS, Institut de Biologie Paris Seine (IBPS), F-75005, Paris, France. .,Institut de Systématique, Evolution, Biodiversité (ISYEB), Museum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, 57, rue Cuvier, 75005, Paris, France.
| | - P Graça
- Laboratoire Evolution Paris Seine, Sorbonne Université, Univ Antilles, CNRS, Institut de Biologie Paris Seine (IBPS), F-75005, Paris, France
| | - L Belkadi
- Institut Pasteur, Laboratoire Signalisation et Pathogénèse, UMR CNRS 3691, Bâtiment DARRE, 25-28 rue du Dr Roux, 75015, Paris, France
| | - L Petit
- Plateforme d'Imagerie et Cytométrie en flux, Sorbonne Université, CNRS, - Institut de Biologie Paris-Seine (BDPS - IBPS), F-75005, Paris, France
| | - E Bonnivard
- Laboratoire Evolution Paris Seine, Sorbonne Université, Univ Antilles, CNRS, Institut de Biologie Paris Seine (IBPS), F-75005, Paris, France
| | - A Dettaï
- Institut de Systématique, Evolution, Biodiversité (ISYEB), Museum National d'Histoire Naturelle, CNRS, Sorbonne Université, EPHE, 57, rue Cuvier, 75005, Paris, France
| | - W H Detrich
- Department of Marine and Environmental Sciences, Marine Science Center, Northeastern University, Nahant, MA, 01908, USA
| | - C Ozouf-Costaz
- Laboratoire Evolution Paris Seine, Sorbonne Université, Univ Antilles, CNRS, Institut de Biologie Paris Seine (IBPS), F-75005, Paris, France
| | - D Higuet
- Laboratoire Evolution Paris Seine, Sorbonne Université, Univ Antilles, CNRS, Institut de Biologie Paris Seine (IBPS), F-75005, Paris, France
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Craddock EM, Gall JG, Jonas M. Hawaiian Drosophila genomes: size variation and evolutionary expansions. Genetica 2016; 144:107-24. [PMID: 26790663 DOI: 10.1007/s10709-016-9882-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2015] [Accepted: 01/09/2016] [Indexed: 01/24/2023]
Abstract
This paper reports genome sizes of one Hawaiian Scaptomyza and 16 endemic Hawaiian Drosophila species that include five members of the antopocerus species group, one member of the modified mouthpart group, and ten members of the picture wing clade. Genome size expansions have occurred independently multiple times among Hawaiian Drosophila lineages, and have resulted in an over 2.3-fold range of genome sizes among species, with the largest observed in Drosophila cyrtoloma (1C = 0.41 pg). We find evidence that these repeated genome size expansions were likely driven by the addition of significant amounts of heterochromatin and satellite DNA. For example, our data reveal that the addition of seven heterochromatic chromosome arms to the ancestral haploid karyotype, and a remarkable proportion of ~70 % satellite DNA, account for the greatly expanded size of the D. cyrtoloma genome. Moreover, the genomes of 13/17 Hawaiian picture wing species are composed of substantial proportions (22-70 %) of detectable satellites (all but one of which are AT-rich). Our results suggest that in this tightly knit group of recently evolved species, genomes have expanded, in large part, via evolutionary amplifications of satellite DNA sequences in centric and pericentric domains (especially of the X and dot chromosomes), which have resulted in longer acrocentric chromosomes or metacentrics with an added heterochromatic chromosome arm. We discuss possible evolutionary mechanisms that may have shaped these patterns, including rapid fixation of novel expanded genomes during founder-effect speciation.
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Affiliation(s)
- Elysse M Craddock
- Natural Sciences Building, Purchase College, State University of New York, 735 Anderson Hill Road, Purchase, NY, 10577, USA.
| | - Joseph G Gall
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD, USA
| | - Mark Jonas
- Natural Sciences Building, Purchase College, State University of New York, 735 Anderson Hill Road, Purchase, NY, 10577, USA
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Tsoumani KT, Drosopoulou E, Bourtzis K, Gariou-Papalexiou A, Mavragani-Tsipidou P, Zacharopoulou A, Mathiopoulos KD. Achilles, a New Family of Transcriptionally Active Retrotransposons from the Olive Fruit Fly, with Y Chromosome Preferential Distribution. PLoS One 2015; 10:e0137050. [PMID: 26398504 PMCID: PMC4580426 DOI: 10.1371/journal.pone.0137050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/13/2015] [Indexed: 11/19/2022] Open
Abstract
Sex chromosomes have many unusual features relative to autosomes. The in depth exploration of their structure will improve our understanding of their origin and divergence (degeneration) as well as the evolution of genetic sex determination pathways which, most often are attributed to them. In Tephritids, the structure of Y chromosome, where the male-determining factor M is localized, is largely unexplored and limited data concerning its sequence content and evolution are available. In order to get insight into the structure and organization of the Y chromosome of the major olive insect pest, the olive fly Bactrocera oleae, we characterized sequences from a Pulse Field Gel Electrophoresis (PFGE)-isolated Y chromosome. Here, we report the discovery of the first olive fly LTR retrotransposon with increased presence on the Y chromosome. The element belongs to the BEL-Pao superfamily, however, its sequence comparison with the other members of the superfamily suggests that it constitutes a new family that we termed Achilles. Its ~7.5 kb sequence consists of the 5'LTR, the 5'non-coding sequence and the open reading frame (ORF), which encodes the polyprotein Gag-Pol. In situ hybridization to the B. oleae polytene chromosomes showed that Achilles is distributed in discrete bands dispersed on all five autosomes, in all centromeric regions and in the granular heterochromatic network corresponding to the mitotic sex chromosomes. The between sexes comparison revealed a variation in Achilles copy number, with male flies possessing 5-10 copies more than female (CI range: 18-38 and 12-33 copies respectively per genome). The examination of its transcriptional activity demonstrated the presence of at least one intact active copy in the genome, showing a differential level of expression between sexes as well as during embryonic development. The higher expression was detected in male germline tissues (testes). Moreover, the presence of Achilles-like elements in different species of the Tephritidae family suggests an ancient origin of this element.
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Affiliation(s)
| | - Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece
| | - Kostas Bourtzis
- Insect Molecular Genetics Group, IMBB, Vassilika Vouton, 71110 Heraklion, Crete, PO Box 1527, Greece
- Department of Environmental and Natural Resources Management, University of Patras, Agrinio, Greece
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Aggeliki Gariou-Papalexiou
- Department of Biology, Division of Genetics, Cell and Developmental Biology, University of Patras, Patras, Greece
| | - Penelope Mavragani-Tsipidou
- Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece
| | - Antigone Zacharopoulou
- Department of Biology, Division of Genetics, Cell and Developmental Biology, University of Patras, Patras, Greece
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Gruber SL, Diniz D, Sobrinho-Scudeler PE, Fausto Foresti, Haddad CFB, Kasahara S. Possible interspecific origin of the B chromosome of Hypsiboas albopunctatus (Spix, 1824) (Anura, Hylidae), revealed by microdissection, chromosome painting, and reverse hybridisation. COMPARATIVE CYTOGENETICS 2014; 8:185-97. [PMID: 25349670 PMCID: PMC4205488 DOI: 10.3897/compcytogen.v8i3.7771] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Accepted: 06/09/2014] [Indexed: 03/22/2024]
Abstract
The B chromosome in the hylid Hypsiboas albopunctatus (2n = 22 + B) is small, almost entirely composed of C-positive heterochromatin, and does not pair with any chromosome of the A complement. B probe, obtained by microdissection and DOP-PCR amplification, was used to search for homology between the B and regular chromosomes of H. albopunctatus and of the related species H. raniceps (Cope, 1862). Reverse hybridisation was also carried out in the investigation. The B probe exclusively painted the supernumerary, not hybridising any other chromosomes in H. albopunctatus, but all H. raniceps chromosomes showed small labelling signals. This result might be an indication that differences exist between the repetitive sequences of A and B chromosomes of H. albopunctatus, and that the chromosomes of H. raniceps and the heterochromatin of the B chromosome of H. albopunctatus are enriched with the same type of repetitive DNA. In meiotic preparations, the B labelled about 30% of scored spermatids, revealing a non-mendelian inheritance, and the painted B in micronucleus suggests that the supernumerary is eliminated from germ line cells. Although our results could suggest an interespecific origin of the B at first sight, further analysis on its repetitive sequences is still necessary. Nevertheless, the accumulation of repetitive sequences, detected in another species, even though closely related, remains an intriguing question.
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Affiliation(s)
- Simone Lilian Gruber
- UNESP, Universidade Estadual Paulista, Instituto de Biociências, Departamento de Biologia, Av. 24A 1515, 13506-900, Rio Claro, SP, Brazil
| | - Débora Diniz
- UESB, Universidade Estadual do Sudoeste da Bahia, Departamento de Ciências Biológicas, Rua José Moreira Sobrinho s/n, Jequiezinho, 45206-190, Jequié, BA, Brazil
| | - Patrícia Elda Sobrinho-Scudeler
- UNESP, Universidade Estadual Paulista, Instituto de Biociências, Departamento de Morfologia, Distrito de Rubião Júnior s/n, 18618-970, Botucatu, SP, Brazil
| | - Fausto Foresti
- UNESP, Universidade Estadual Paulista, Instituto de Biociências, Departamento de Morfologia, Distrito de Rubião Júnior s/n, 18618-970, Botucatu, SP, Brazil
| | - Célio Fernando Baptista Haddad
- UNESP, Universidade Estadual Paulista, Instituto de Biociências, Departamento de Zoologia, Av. 24A 1515, 13506-900, Rio Claro, SP, Brazil
| | - Sanae Kasahara
- UNESP, Universidade Estadual Paulista, Instituto de Biociências, Departamento de Biologia, Av. 24A 1515, 13506-900, Rio Claro, SP, Brazil
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Ladevèze V, Chaminade N, Lemeunier F, Periquet G, Aulard S. General survey of hAT transposon superfamily with highlight on hobo element in Drosophila. Genetica 2012; 140:375-92. [DOI: 10.1007/s10709-012-9687-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2012] [Accepted: 10/10/2012] [Indexed: 11/30/2022]
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Commar LS, Galego LGDC, Ceron CR, Carareto CMA. Taxonomic and evolutionary analysis of Zaprionus indianus and its colonization of Palearctic and Neotropical regions. Genet Mol Biol 2012; 35:395-406. [PMID: 22888286 PMCID: PMC3389525 DOI: 10.1590/s1415-47572012000300003] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2011] [Accepted: 02/28/2012] [Indexed: 11/21/2022] Open
Abstract
Zaprionus indianus is a dipteran (Drosophilidae) with a wide distribution throughout the tropics and temperate Palearctic and Nearctic regions. There have been proposals to reclassify the genus Zaprionus as a subgenus or group of the genus Drosophila because various molecular markers have indicated a close relationship between Zaprionus species and the immigrans-Hirtodrosophila radiation within Drosophila. These markers, together with alloenzymes and quantitative traits, have been used to describe the probable scenario for the expansion of Zaprionus indianus from its center of dispersal (Africa) to regions of Asia (ancient dispersal) and the Americas (recent dispersal). The introduction of Z. indianus into Brazil was first reported in 1999 and the current consensus is that the introduced flies came from high-latitude African populations through the importation of fruit. Once in Brazil, Z. indianus spread rapidly throughout the Southeast and then to the rest of the country, in association with highway-based fruit commerce. These and other aspects of the evolutionary biology of Z. indianus are addressed in this review, including a description of a probable route for this species’ dispersal during its recent expansion.
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Affiliation(s)
- Leliane Silva Commar
- Departamento de Biologia, Universidade Estadual Paulista "Júlio de Mesquita Filho", São José do Rio Preto, SP, Brazil
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11
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Vonholdt BM, Takuno S, Gaut BS. Recent retrotransposon insertions are methylated and phylogenetically clustered in japonica rice (Oryza sativa spp. japonica). Mol Biol Evol 2012; 29:3193-203. [PMID: 22593226 DOI: 10.1093/molbev/mss129] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
In plants, the genome of the host responds to the amplification of transposable elements (TEs) with DNA methylation. However, neither the factors involved in TE methylation nor the dynamics of the host-TE interaction are well resolved. Here, we identify 5,522 long terminal repeat retrotransposons (LTR-RT) in the genome of Oryza sativa ssp. japonica and then assess methylation for individual elements. Our analyses uncover three strong trends: long LTR-RTs are more highly methylated, the insertion times of LTR-RTs are negatively correlated with methylation, and young LTR-RTs tend to be closer to genes than older insertions. Additionally, a phylogenetic examination of the gypsy-like LTR-RT superfamily revealed that methylation is phylogenetically correlated. Given these observations, we present a model suggesting that the phylogenetic correlation among related LTR-RTs is a primary mechanism driving methylation. In this model, bursts of transposition produce new elements with high sequence similarity. The host machinery identifies proliferating elements as well as closely related LTR-RTs through cross-homology. In addition, our data are consistent with previous hypotheses that methylated LTR-RT elements are removed preferentially from regions near genes, explaining some of the observed age distribution.
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Affiliation(s)
- Bridgett M Vonholdt
- Department of Ecology and Evolutionary Biology, University of California, Irvine, CA, USA.
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12
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Vasil’eva LA, Antonenko OV, Zakharov IK. Role of transposable elements in the genome of Drosophila melanogaster. ACTA ACUST UNITED AC 2011. [DOI: 10.1134/s2079059711060128] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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13
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Zampicinini G, Cervella P, Biémont C, Sella G. Insertional variability of four transposable elements and population structure of the midge Chironomus riparius (Diptera). Mol Genet Genomics 2011; 286:293-305. [PMID: 21901555 DOI: 10.1007/s00438-011-0646-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2010] [Accepted: 08/16/2011] [Indexed: 11/29/2022]
Abstract
The dipteran Chironomus riparius is found across the entire Palearctic region; its larvae are among the most abundant macroinvertebrates inhabiting inland waterbodies. Chironomid larvae have been extensively used in ecotoxicological and cytogenetic research, but relatively little is known on the population structure of this species. Transposable elements (TEs) are DNA sequences that are capable of autonomous replication; the number and genomic location of TE insertions varies across individuals; this variability is increasingly being used in population studies. Several TEs had been characterized in Chironomids; this enabled the analysis of insertional variability of four different TEs in six natural populations of C. riparius from Italy, Bulgaria and Russia using a PCR-based method, transposon insertion display (TID). The method allows to obtain dominant markers, similar to AFLP. In all populations, TE insertions showed high individual polymorphism, while median copy numbers of the same TEs did not vary between populations. Analysis of molecular variance (AMOVA) detected significant differentiation between populations for three of the TEs; although no correlation between genetic and geographic distances was found, the corresponding population structures were found to be significantly correlated and indicate a degree of isolation by distance. TEs belonging to different classes have different mechanisms of replication, resulting in different transposition rates of mobilization; the finding of mostly concordant population structuring for three of the TEs indicates that population dynamics contributed significantly in shaping the detected insertional polymorphism.
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Affiliation(s)
- Giampaolo Zampicinini
- Dipartimento di Biologia Animale e dell'Uomo, Università di Torino, Via Accademia Albertina 13, 10123 Turin, Italy
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Abstract
Mutation rates vary significantly within the genome and across species. Recent studies revealed a long suspected replication-timing effect on mutation rate, but the mechanisms that regulate the increase in mutation rate as the genome is replicated remain unclear. Evidence is emerging, however, that DNA repair systems, in general, are less efficient in late replicating heterochromatic regions compared to early replicating euchromatic regions of the genome. At the same time, mutation rates in both vertebrates and invertebrates have been shown to vary with generation time (GT). GT is correlated with genome size, which suggests a possible nucleotypic effect on species-specific mutation rates. These and other observations all converge on a role for DNA replication checkpoints in modulating generation times and mutation rates during the DNA synthetic phase (S phase) of the cell cycle. The following will examine the potential role of the intra-S checkpoint in regulating cell cycle times (GT) and mutation rates in eukaryotes. This article was published online on August 5, 2011. An error was subsequently identified. This notice is included in the online and print versions to indicate that both have been corrected October 4, 2011.
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Affiliation(s)
- John Herrick
- Department of Physics, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia, Canada.
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15
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Lu J, Clark AG. Population dynamics of PIWI-interacting RNAs (piRNAs) and their targets in Drosophila. Genome Res 2009; 20:212-27. [PMID: 19948818 DOI: 10.1101/gr.095406.109] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Transposable elements (TEs) are mobile DNA sequences that make up a large fraction of eukaryotic genomes. Recently it was discovered that PIWI-interacting RNAs (piRNAs), a class of small RNA molecules that are mainly generated from transposable elements, are crucial repressors of active TEs in the germline of fruit flies. By quantifying expression levels of 32 TE families in piRNA pathway mutants relative to wild-type fruit flies, we provide evidence that piRNAs can severely silence the activities of retrotransposons. We incorporate piRNAs into a population genetic framework for retrotransposons and perform forward simulations to model the population dynamics of piRNA loci and their targets. Using parameters optimized for Drosophila melanogaster, our simulation results indicate that (1) piRNAs can significantly reduce the fitness cost of retrotransposons; (2) retrotransposons that generate piRNAs (piRTs) are selectively more advantageous, and such retrotransposon insertions more easily attain high frequency or fixation; (3) retrotransposons that are repressed by piRNAs (targetRTs), however, also have an elevated probability of reaching high frequency or fixation in the population because their deleterious effects are attenuated. By surveying the polymorphisms of piRT and targetRT insertions across nine strains of D. melanogaster, we verified these theoretical predictions with population genomic data. Our theoretical and empirical analysis suggests that piRNAs can significantly increase the fitness of individuals that bear them; however, piRNAs may provide a shelter or Trojan horse for retrotransposons, allowing them to increase in frequency in a population by shielding the host from the deleterious consequences of retrotransposition.
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Affiliation(s)
- Jian Lu
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
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16
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Sackton TB, Kulathinal RJ, Bergman CM, Quinlan AR, Dopman EB, Carneiro M, Marth GT, Hartl DL, Clark AG. Population genomic inferences from sparse high-throughput sequencing of two populations of Drosophila melanogaster. Genome Biol Evol 2009; 1:449-65. [PMID: 20333214 PMCID: PMC2839279 DOI: 10.1093/gbe/evp048] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/14/2009] [Indexed: 12/20/2022] Open
Abstract
Short-read sequencing techniques provide the opportunity to capture genome-wide sequence data in a single experiment. A current challenge is to identify questions that shallow-depth genomic data can address successfully and to develop corresponding analytical methods that are statistically sound. Here, we apply the Roche/454 platform to survey natural variation in strains of Drosophila melanogaster from an African (n = 3) and a North American (n = 6) population. Reads were aligned to the reference D. melanogaster genomic assembly, single nucleotide polymorphisms were identified, and nucleotide variation was quantified genome wide. Simulations and empirical results suggest that nucleotide diversity can be accurately estimated from sparse data with as little as 0.2x coverage per line. The unbiased genomic sampling provided by random short-read sequencing also allows insight into distributions of transposable elements and copy number polymorphisms found within populations and demonstrates that short-read sequencing methods provide an efficient means to quantify variation in genome organization and content. Continued development of methods for statistical inference of shallow-depth genome-wide sequencing data will allow such sparse, partial data sets to become the norm in the emerging field of population genomics.
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Affiliation(s)
- Timothy B Sackton
- Department of Organismic and Evolutionary Biology, Harvard University, Boston, MA, USA.
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17
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Lichtenberg J, Yilmaz A, Welch JD, Kurz K, Liang X, Drews F, Ecker K, Lee SS, Geisler M, Grotewold E, Welch LR. The word landscape of the non-coding segments of the Arabidopsis thaliana genome. BMC Genomics 2009; 10:463. [PMID: 19814816 PMCID: PMC2770528 DOI: 10.1186/1471-2164-10-463] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2009] [Accepted: 10/08/2009] [Indexed: 11/23/2022] Open
Abstract
Background Genome sequences can be conceptualized as arrangements of motifs or words. The frequencies and positional distributions of these words within particular non-coding genomic segments provide important insights into how the words function in processes such as mRNA stability and regulation of gene expression. Results Using an enumerative word discovery approach, we investigated the frequencies and positional distributions of all 65,536 different 8-letter words in the genome of Arabidopsis thaliana. Focusing on promoter regions, introns, and 3' and 5' untranslated regions (3'UTRs and 5'UTRs), we compared word frequencies in these segments to genome-wide frequencies. The statistically interesting words in each segment were clustered with similar words to generate motif logos. We investigated whether words were clustered at particular locations or were distributed randomly within each genomic segment, and we classified the words using gene expression information from public repositories. Finally, we investigated whether particular sets of words appeared together more frequently than others. Conclusion Our studies provide a detailed view of the word composition of several segments of the non-coding portion of the Arabidopsis genome. Each segment contains a unique word-based signature. The respective signatures consist of the sets of enriched words, 'unwords', and word pairs within a segment, as well as the preferential locations and functional classifications for the signature words. Additionally, the positional distributions of enriched words within the segments highlight possible functional elements, and the co-associations of words in promoter regions likely represent the formation of higher order regulatory modules. This work is an important step toward fully cataloguing the functional elements of the Arabidopsis genome.
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Affiliation(s)
- Jens Lichtenberg
- Bioinformatics Laboratory, School of Electrical Engineering and Computer Science, Ohio University, Athens, OH, USA.
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Rasmussen DA, Noor MAF. What can you do with 0.1x genome coverage? A case study based on a genome survey of the scuttle fly Megaselia scalaris (Phoridae). BMC Genomics 2009; 10:382. [PMID: 19689807 PMCID: PMC2735751 DOI: 10.1186/1471-2164-10-382] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2009] [Accepted: 08/18/2009] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND The declining cost of DNA sequencing is making genome sequencing a feasible option for more organisms, including many of interest to ecologists and evolutionary biologists. While obtaining high-depth, completely assembled genome sequences for most non-model organisms remains challenging, low-coverage genome survey sequences (GSS) can provide a wealth of biologically useful information at low cost. Here, using a random pyrosequencing approach, we sequence the genome of the scuttle fly Megaselia scalaris and evaluate the utility of our low-coverage GSS approach. RESULTS Random pyrosequencing of the M. scalaris genome provided a depth of coverage (0.05x0.1x) much lower than typical GSS studies. We demonstrate that, even with extremely low-coverage sequencing, bioinformatics approaches can yield extensive information about functional and repetitive elements. We also use our GSS data to develop genomic resources such as a nearly complete mitochondrial genome sequence and microsatellite markers for M. scalaris. CONCLUSION We conclude that low-coverage genome surveys are effective at generating useful information about organisms currently lacking genomic sequence data.
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Venner S, Feschotte C, Biémont C. Dynamics of transposable elements: towards a community ecology of the genome. Trends Genet 2009; 25:317-23. [PMID: 19540613 PMCID: PMC2945704 DOI: 10.1016/j.tig.2009.05.003] [Citation(s) in RCA: 111] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2008] [Revised: 05/27/2009] [Accepted: 05/28/2009] [Indexed: 12/13/2022]
Abstract
Like ecological communities, which vary in species composition, eukaryote genomes differ in the amount and diversity of transposable elements (TEs) that they harbor. Given that TEs have a considerable impact on the biology of their host species, we need to better understand whether their dynamics reflects some form of organization or is primarily driven by stochastic processes. Here, we borrow ecological concepts on species diversity to explore how interactions between TEs can contribute to structure TE communities within their genomic ecosystem. Whereas the niche theory predicts a stable diversity of TEs because of their divergent characteristics, the neutral theory of biodiversity predicts the assembly of TE communities from stochastic processes acting at the level of the individual TE. Contrary to ecological communities, however, TE communities are shaped by selection at the level of their ecosystem (i.e. the host individual). Developing ecological models specific to the genome will thus be a prerequisite for modeling the dynamics of TEs.
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20
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Venner S, Feschotte C, Biémont C. Dynamics of transposable elements: towards a community ecology of the genome. Trends Genet 2009. [PMID: 19540613 DOI: 10.1016/j.tig.2009.05.003.epub] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Like ecological communities, which vary in species composition, eukaryote genomes differ in the amount and diversity of transposable elements (TEs) that they harbor. Given that TEs have a considerable impact on the biology of their host species, we need to better understand whether their dynamics reflects some form of organization or is primarily driven by stochastic processes. Here, we borrow ecological concepts on species diversity to explore how interactions between TEs can contribute to structure TE communities within their genomic ecosystem. Whereas the niche theory predicts a stable diversity of TEs because of their divergent characteristics, the neutral theory of biodiversity predicts the assembly of TE communities from stochastic processes acting at the level of the individual TE. Contrary to ecological communities, however, TE communities are shaped by selection at the level of their ecosystem (i.e. the host individual). Developing ecological models specific to the genome will thus be a prerequisite for modeling the dynamics of TEs.
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21
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Patrushev LI, Minkevich IG. The problem of the eukaryotic genome size. BIOCHEMISTRY (MOSCOW) 2009; 73:1519-52. [PMID: 19216716 DOI: 10.1134/s0006297908130117] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The current state of knowledge concerning the unsolved problem of the huge interspecific eukaryotic genome size variations not correlating with the species phenotypic complexity (C-value enigma also known as C-value paradox) is reviewed. Characteristic features of eukaryotic genome structure and molecular mechanisms that are the basis of genome size changes are examined in connection with the C-value enigma. It is emphasized that endogenous mutagens, including reactive oxygen species, create a constant nuclear environment where any genome evolves. An original quantitative model and general conception are proposed to explain the C-value enigma. In accordance with the theory, the noncoding sequences of the eukaryotic genome provide genes with global and differential protection against chemical mutagens and (in addition to the anti-mutagenesis and DNA repair systems) form a new, third system that protects eukaryotic genetic information. The joint action of these systems controls the spontaneous mutation rate in coding sequences of the eukaryotic genome. It is hypothesized that the genome size is inversely proportional to functional efficiency of the anti-mutagenesis and/or DNA repair systems in a particular biological species. In this connection, a model of eukaryotic genome evolution is proposed.
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Affiliation(s)
- L I Patrushev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia.
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22
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Fablet M, Lerat E, Rebollo R, Horard B, Burlet N, Martinez S, Brasset E, Gilson E, Vaury C, Vieira C. Genomic environment influences the dynamics of the tirant LTR retrotransposon in Drosophila. FASEB J 2009; 23:1482-9. [PMID: 19141532 DOI: 10.1096/fj.08-123513] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Combining genome sequence analysis and functional analysis, we show that some full-length copies of tirant are present in heterochromatic regions in Drosophila simulans and that when tested in vitro, these copies have a functional promoter. However, when inserted in heterochromatic regions, tirant copies are inactive in vivo, and only transcription of euchromatic copies can be detected. Thus, our data indicate that the localization of the element is a hallmark of its activity in vivo and raise the question of genomic invasions by transposable elements and the importance of their genomic integration sites.
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Affiliation(s)
- Marie Fablet
- Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, France
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23
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Distribution of ancestral proto-Actinopterygian chromosome arms within the genomes of 4R-derivative salmonid fishes (Rainbow trout and Atlantic salmon). BMC Genomics 2008; 9:557. [PMID: 19032764 PMCID: PMC2632648 DOI: 10.1186/1471-2164-9-557] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 11/25/2008] [Indexed: 11/23/2022] Open
Abstract
Background Comparative genomic studies suggest that the modern day assemblage of ray-finned fishes have descended from an ancestral grouping of fishes that possessed 12–13 linkage groups. All jawed vertebrates are postulated to have experienced two whole genome duplications (WGD) in their ancestry (2R duplication). Salmonids have experienced one additional WGD (4R duplication event) compared to most extant teleosts which underwent a further 3R WGD compared to other vertebrates. We describe the organization of the 4R chromosomal segments of the proto-ray-finned fish karyotype in Atlantic salmon and rainbow trout based upon their comparative syntenies with two model species of 3R ray-finned fishes. Results Evidence is presented for the retention of large whole-arm affinities between the ancestral linkage groups of the ray-finned fishes, and the 50 homeologous chromosomal segments in Atlantic salmon and rainbow trout. In the comparisons between the two salmonid species, there is also evidence for the retention of large whole-arm homeologous affinities that are associated with the retention of duplicated markers. Five of the 7 pairs of chromosomal arm regions expressing the highest level of duplicate gene expression in rainbow trout share homologous synteny to the 5 pairs of homeologs with the greatest duplicate gene expression in Atlantic salmon. These regions are derived from proto-Actinopterygian linkage groups B, C, E, J and K. Conclusion Two chromosome arms in Danio rerio and Oryzias latipes (descendants of the 3R duplication) can, in most instances be related to at least 4 whole or partial chromosomal arms in the salmonid species. Multiple arm assignments in the two salmonid species do not clearly support a 13 proto-linkage group model, and suggest that a 12 proto-linkage group arrangement (i.e., a separate single chromosome duplication and ancestral fusion/fissions/recombination within the putative G/H/I groupings) may have occurred in the more basal soft-rayed fishes. We also found evidence supporting the model that ancestral linkage group M underwent a single chromosome duplication following the 3R duplication. In the salmonids, the M ancestral linkage groups are localized to 5 whole arm, and 3 partial arm regions (i.e., 6 whole arm regions expected). Thus, 3 distinct ancestral linkage groups are postulated to have existed in the G/H and M lineage chromosomes in the ancestor of the salmonids.
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Sparagano OAE, De Luna CJ. From population structure to genetically-engineered vectors: New ways to control vector-borne diseases? INFECTION GENETICS AND EVOLUTION 2008; 8:520-5. [PMID: 17560836 DOI: 10.1016/j.meegid.2007.05.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2007] [Revised: 05/01/2007] [Indexed: 11/18/2022]
Abstract
Epidemiological studies on vectors and the pathogens they can carry (such as Borrelia burgdorferi) are showing some correlations between infection rates and biodiversity highlighting the "dilution" effects on potential vectors. Meanwhile other studies comparing sympatric small rodent species demonstrated that rodent species transmitting more pathogens are parasitized by more ectoparasite species. Studies on population structure and size have also proven a difference on the intensity of the parasitic infection. Furthermore, preliminary results in genetic improvement in mosquitoes (genetic markers, sexing, and genetic sterilization) will also increase performance as it has already been shown in field applications in developing countries. Recent results have greatly improved the fitness of genetically-modified insects compared to wild type populations with new approaches such as the post-integration elimination of transposon sequences, stabilising any insertion in genetically-modified insects. Encouraging results using the Sterile Insect Technique highlighted some metabolism manipulation to avoid the viability of offspring from released parent insect in the wild. Recent studies on vector symbionts would also bring a new angle in vector control capabilities, while complete DNA sequencing of some arthropods could point out ways to block the deadly impact on animal and human populations. These new potential approaches will improve the levels of control or even in some cases would eradicate vector species and consequently the vector-borne diseases they can transmit. In this paper we review some of the population biology theories, biological control methods, and the genetic techniques that have been published in the last years that are recommended to control for vector-borne diseases.
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Affiliation(s)
- O A E Sparagano
- School of Agriculture, Food, and Rural Development, Agriculture Building, Newcastle University, Newcastle upon Tyne, UK.
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26
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Yang HP, Barbash DA. Abundant and species-specific DINE-1 transposable elements in 12 Drosophila genomes. Genome Biol 2008; 9:R39. [PMID: 18291035 PMCID: PMC2374699 DOI: 10.1186/gb-2008-9-2-r39] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2007] [Revised: 12/17/2007] [Accepted: 02/21/2008] [Indexed: 02/08/2023] Open
Abstract
Evidence is presented that DINE-1 is a highly abundant miniature inverted-repeat transposable element (MITE) family present in all 12 Drosophila species with whole-genome sequence available. Background Miniature inverted-repeat transposable elements (MITEs) are non-autonomous DNA-mediated transposable elements (TEs) derived from autonomous TEs. Unlike in many plants or animals, MITEs and other types of DNA-mediated TEs were previously thought to be either rare or absent in Drosophila. Most other TE families in Drosophila exist at low or intermediate copy number (around < 100 per genome). Results We present evidence here that the dispersed repeat Drosophila interspersed element 1 (DINE-1; also named INE-1 and DNAREP1) is a highly abundant DNA-mediated TE containing inverted repeats found in all 12 sequenced Drosophila genomes. All DINE-1s share a similar sequence structure, but are more homogeneous within species than they are among species. The inferred phylogenetic relationship of the DINE-1 consensus sequence from each species is generally consistent with the known species phylogeny, suggesting vertical transmission as the major mechanism for DINE-1 propagation. Exceptions observed in D. willistoni and D. ananassae could be due to either horizontal transfer or reactivation of ancestral copies. Our analysis of pairwise percentage identity of DINE-1 copies within species suggests that the transpositional activity of DINE-1 is extremely dynamic, with some lineages showing evidence for recent transpositional bursts and other lineages appearing to have silenced their DINE-1s for long periods of time. We also find that all species have many DINE-1 insertions in introns and adjacent to protein-coding genes. Finally, we discuss our results in light of a recent proposal that DINE-1s belong to the Helitron family of TEs. Conclusion We find that all 12 Drosophila species with whole-genome sequence contain the high copy element DINE-1. Although all DINE-1s share a similar structure, species-specific variation in the distribution of average pairwise divergence suggests that DINE-1 has gone through multiple independent cycles of activation and suppression. DINE-1 also has had a significant impact on gene structure evolution.
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Affiliation(s)
- Hsiao-Pei Yang
- Institute of Genetics, National Yang-Ming University, Taipei 112, Taiwan.
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27
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Mugnier N, Gueguen L, Vieira C, Biémont C. The heterochromatic copies of the LTR retrotransposons as a record of the genomic events that have shaped the Drosophila melanogaster genome. Gene 2008; 411:87-93. [PMID: 18281162 DOI: 10.1016/j.gene.2008.01.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2007] [Revised: 01/14/2008] [Accepted: 01/16/2008] [Indexed: 11/29/2022]
Abstract
Transposable elements, which are major components of most genomes, are known to accumulate in heterochromatic regions in which they have progressively diverged in sequence by mutations and internal deletions and insertions (indels) during the course of evolution. They therefore provide a record of the genomic events that have shaped the genomes, some of which could correspond to speciation events. Using the sequence divergence between the long terminal repeats (LTRs), we estimated the date of the insertion events of the LTR retrotransposon copies embedded within the heterochromatin regions of the Drosophila melanogaster genome. We did not detect traces of any specific waves of mobilization of retrotransposons within heterochromatin, apart from a very recent wave, which corresponds to the numerous LTR retrotransposon copies found in euchromatin.
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Affiliation(s)
- Nathalie Mugnier
- Biométrie et Biologie Evolutive, UMR 5558, CNRS, Université Lyon 1, Université de Lyon, 69622 Villeurbanne cedex, France
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28
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Pavlopoulos A, Oehler S, Kapetanaki MG, Savakis C. The DNA transposon Minos as a tool for transgenesis and functional genomic analysis in vertebrates and invertebrates. Genome Biol 2007; 8 Suppl 1:S2. [PMID: 18047694 PMCID: PMC2106841 DOI: 10.1186/gb-2007-8-s1-s2] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Transposons are powerful tools for conducting genetic manipulation and functional studies in organisms that are of scientific, economic, or medical interest. Minos, a member of the Tc1/mariner family of DNA transposons, exhibits a low insertional bias and transposes with high frequency in vertebrates and invertebrates. Its use as a tool for transgenesis and genome analysis of rather different animal species is described.
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Affiliation(s)
- Anastasios Pavlopoulos
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Vassilika Vouton, PO Box 1385, Heraklion 71110, Crete, Greece
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29
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de Boer JG, Yazawa R, Davidson WS, Koop BF. Bursts and horizontal evolution of DNA transposons in the speciation of pseudotetraploid salmonids. BMC Genomics 2007; 8:422. [PMID: 18021408 PMCID: PMC2198921 DOI: 10.1186/1471-2164-8-422] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2007] [Accepted: 11/16/2007] [Indexed: 11/17/2022] Open
Abstract
Background Several genome duplications have occurred in the evolutionary history of teleost fish. In returning to a stable diploid state, the polyploid genome reorganized, and large portions are lost, while the fish lines evolved to numerous species. Large scale transposon movement has been postulated to play an important role in the genome reorganization process. We analyzed the DNA sequence of several large loci in Salmo salar and other species for the presence of DNA transposon families. Results We have identified bursts of activity of 14 families of DNA transposons (12 Tc1-like and 2 piggyBac-like families, including 11 novel ones) in genome sequences of Salmo salar. Several of these families have similar sequences in a number of closely and distantly related fish, lamprey, and frog species as well as in the parasite Schistosoma japonicum. Analysis of sequence similarities between copies within the families of these bursts demonstrates several waves of transposition activities coinciding with salmonid species divergence. Tc1-like families show a master gene-like copying process, illustrated by extensive but short burst of copying activity, while the piggyBac-like families show a more random copying pattern. Recent families may include copies with an open reading frame for an active transposase enzyme. Conclusion We have identified defined bursts of transposon activity that make use of master-slave and random mechanisms. The bursts occur well after hypothesized polyploidy events and coincide with speciation events. Parasite-mediated lateral transfer of transposons are implicated.
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Affiliation(s)
- Johan G de Boer
- Centre for Biomedical Research, University of Victoria, Victoria, BC V8W 2Y2 Canada.
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Fontanillas P, Hartl DL, Reuter M. Genome organization and gene expression shape the transposable element distribution in the Drosophila melanogaster euchromatin. PLoS Genet 2007; 3:e210. [PMID: 18081425 PMCID: PMC2098804 DOI: 10.1371/journal.pgen.0030210] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2007] [Accepted: 10/09/2007] [Indexed: 02/07/2023] Open
Abstract
The distribution of transposable elements (TEs) in a genome reflects a balance between insertion rate and selection against new insertions. Understanding the distribution of TEs therefore provides insights into the forces shaping the organization of genomes. Past research has shown that TEs tend to accumulate in genomic regions with low gene density and low recombination rate. However, little is known about the factors modulating insertion rates across the genome and their evolutionary significance. One candidate factor is gene expression, which has been suggested to increase local insertion rate by rendering DNA more accessible. We test this hypothesis by comparing the TE density around germline- and soma-expressed genes in the euchromatin of Drosophila melanogaster. Because only insertions that occur in the germline are transmitted to the next generation, we predicted a higher density of TEs around germline-expressed genes than soma-expressed genes. We show that the rate of TE insertions is greater near germline- than soma-expressed genes. However, this effect is partly offset by stronger selection for genome compactness (against excess noncoding DNA) on germline-expressed genes. We also demonstrate that the local genome organization in clusters of coexpressed genes plays a fundamental role in the genomic distribution of TEs. Our analysis shows that-in addition to recombination rate-the distribution of TEs is shaped by the interaction of gene expression and genome organization. The important role of selection for compactness sheds a new light on the role of TEs in genome evolution. Instead of making genomes grow passively, TEs are controlled by the forces shaping genome compactness, most likely linked to the efficiency of gene expression or its complexity and possibly their interaction with mechanisms of TE silencing.
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Affiliation(s)
- Pierre Fontanillas
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Daniel L Hartl
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Max Reuter
- The Galton Laboratory, Department of Biology, University College London, London, United Kingdom
- * To whom correspondence should be addressed. E-mail:
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Abstract
Overlapping epigenetic mechanisms have evolved in eukaryotic cells to silence the expression and mobility of transposable elements (TEs). Owing to their ability to recruit the silencing machinery, TEs have served as building blocks for epigenetic phenomena, both at the level of single genes and across larger chromosomal regions. Important progress has been made recently in understanding these silencing mechanisms. In addition, new insights have been gained into how this silencing has been co-opted to serve essential functions in 'host' cells, highlighting the importance of TEs in the epigenetic regulation of the genome.
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Affiliation(s)
- R Keith Slotkin
- Cold Spring Harbor Laboratory, 1 Bungtown Road, Cold Spring Harbor, New York 11724, USA
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Fablet M, Souames S, Biémont C, Vieira C. Evolutionary pathways of the tirant LTR retrotransposon in the Drosophila melanogaster subgroup of species. J Mol Evol 2007; 64:438-47. [PMID: 17390093 DOI: 10.1007/s00239-006-0108-9] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2006] [Accepted: 01/08/2007] [Indexed: 02/04/2023]
Abstract
Tirant, a LTR retrotransposon with copies scattered over the chromosome arms of Drosophila melanogaster, is in the process of being lost from the chromosome arms of most natural populations of the sister species D. simulans. In an attempt to clarify the dynamics and evolution of tirant, we have studied the regulatory and reverse transcriptase regions in copies of the nine closely related species of the D. melanogaster subgroup. We show that tirant is mainly vertically transmitted in these species, with the exception of a horizontal transfer event from an ancestor of D. melanogaster to D. teissieri. We propose that, in four of the species (D. melanogaster, D. simulans, D. sechellia, and D. mauritiana), the observed patterns of evolution of the regulatory region vary with genome constraints and with the history and biogeography of the species.
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Affiliation(s)
- Marie Fablet
- UMR CNRS 5558, Biométrie et Biologie Evolutive, Université de Lyon Université Lyon 1, Villeurbanne, Cedex
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34
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Fablet M, Rebollo R, Biémont C, Vieira C. The evolution of retrotransposon regulatory regions and its consequences on the Drosophila melanogaster and Homo sapiens host genomes. Gene 2006; 390:84-91. [PMID: 17005332 DOI: 10.1016/j.gene.2006.08.005] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2006] [Revised: 08/11/2006] [Accepted: 08/15/2006] [Indexed: 11/26/2022]
Abstract
It has now been established that transposable elements (TEs) make up a variable, but significant proportion of the genomes of all organisms, from Bacteria to Vertebrates. However, in addition to their quantitative importance, there is increasing evidence that TEs also play a functional role within the genome. In particular, TE regulatory regions can be viewed as a large pool of potential promoter sequences for host genes. Studying the evolution of regulatory region of TEs in different genomic contexts is therefore a fundamental aspect of understanding how a genome works. In this paper, we first briefly describe what is currently known about the regulation of TE copy number and activity in genomes, and then focus on TE regulatory regions and their evolution. We restrict ourselves to retrotransposons, which are the most abundant class of eukaryotic TEs, and analyze their evolution and the subsequent consequences for host genomes. Particular attention is paid to much-studied representatives of the Vertebrates and Invertebrates, Homo sapiens and Drosophila melanogaster, respectively, for which high quality sequenced genomes are available.
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Affiliation(s)
- Marie Fablet
- UMR CNRS 5558, Biométrie et Biologie Evolutive, Université Claude Bernard Lyon 1, 69622 Villeurbanne Cedex, France
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35
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Deceliere G, Letrillard Y, Charles S, Biémont C. TESD: a transposable element dynamics simulation environment. Bioinformatics 2006; 22:2702-3. [PMID: 16928734 DOI: 10.1093/bioinformatics/btl454] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
UNLABELLED Various mathematical models have been used to explore the dynamics of transposable elements (TEs) within their host genomes. However, numerous factors can influence their dynamics, and we know only little about the dynamics of TEs when they first began to invade populations. In addition, the influence of population structuring has only recently been investigated. Transposable Element Simulator Dynamics, a population genomics simulation environment, has therefore been developed to provide a simple tool for analyzing the dynamics of TEs in a community based on (i) various TE parameters, such as the transposition and excision rates, the recombination rate and the coefficient of selection against TE insertions; and (ii) population parameters, such as population size and migration rates. The simulations can be used to illustrate the dynamic fate of TEs in structured populations, can be extended by using more specific molecular or demographic models, and can be useful for teaching population genetics and genomics. AVAILABILITY TESD is distributed under GPL from the Pôle Bioinformatique Lyonnais (PBIL) web server at http://pbil.univ-lyon1.fr/software/TESD
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Affiliation(s)
- Grégory Deceliere
- Laboratoire de Biométrie et Biologie Evolutive (UMR 5558), CNRS, Université Claude Bernard Lyon 1 69622, Villeurbanne Cedex, France
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Fablet M, McDonald JF, Biémont C, Vieira C. Ongoing loss of the tirant transposable element in natural populations of Drosophila simulans. Gene 2006; 375:54-62. [PMID: 16626897 DOI: 10.1016/j.gene.2006.02.008] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2005] [Revised: 01/16/2006] [Accepted: 02/08/2006] [Indexed: 10/24/2022]
Abstract
Tirant is a long terminal repeat (LTR) retrotransposon with an average of 11 insertion sites on the chromosome arms of Drosophila melanogaster flies collected from natural populations worldwide. In the sibling species Drosophila simulans, tirant is found only in African populations, which harbor a few insertion sites (1 to 5) on the chromosome arms, although some tirant sequences are present in the heterochromatin of most populations. This distribution in D. simulans reflects either the recent genomic invasion of African populations by a new variant of tirant, or a loss of tirant from the entire species apart from some sequence relics still present in Africa. In an attempt to clarify the situation, we focused on the LTR-UTR region of tirant copies from various populations of both D. melanogaster and D. simulans. We found two distinct types of regulatory region: one type was present in both D. melanogaster and D. simulans, and the other was present only in D. simulans. Copies of this latter type of tirant were transcriptionally inactive in gonads. Here we propose that the present day distribution of tirant in D. simulans populations reflects an ancient invasion of D. simulans by tirant copies followed by the loss of active copies from most populations, apart from the African ones, suggesting that this loss is still ongoing in this species.
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Affiliation(s)
- Marie Fablet
- UMR CNRS 5558, Biométrie et Biologie Evolutive, Université Claude Bernard Lyon 1, 69622 Villeurbanne Cedex, France
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37
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Dimitri P, Corradini N, Rossi F, Mei E, Zhimulev IF, Vernì F. Transposable elements as artisans of the heterochromatic genome in Drosophila melanogaster. Cytogenet Genome Res 2005; 110:165-72. [PMID: 16093669 DOI: 10.1159/000084949] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Accepted: 11/24/2003] [Indexed: 10/25/2022] Open
Abstract
Over 50 years ago Barbara McClintock discovered that maize contains mobile genetic elements, but her findings were at first considered nothing more than anomalies. Today it is widely recognized that transposable elements have colonized all eukaryotic genomes and represent a major force driving evolution of organisms. Our contribution to this special issue deals with the theme of transposable element-host genome interactions. We bring together published and unpublished work to provide a picture of the contribution of transposable elements to the evolution of the heterochromatic genome in Drosophila melanogaster. In particular, we discuss data on 1) colonization of constitutive heterochromatin by transposable elements, 2) instability of constitutive heterochromatin induced by the I factor, and 3) evolution of constitutive heterochromatin and heterochromatic genes driven by transposable elements. Drawing attention to these topics may have direct implications on important aspects of genome organization and gene expression.
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Affiliation(s)
- P Dimitri
- Dipartimento di Genetica e Biologia Molecolare, Università La Sapienza, Rome, Italy.
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