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Jia H, Tan S, Cai Y, Guo Y, Shen J, Zhang Y, Ma H, Zhang Q, Chen J, Qiao G, Ruan J, Zhang YE. Low-input PacBio sequencing generates high-quality individual fly genomes and characterizes mutational processes. Nat Commun 2024; 15:5644. [PMID: 38969648 PMCID: PMC11226609 DOI: 10.1038/s41467-024-49992-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2023] [Accepted: 06/20/2024] [Indexed: 07/07/2024] Open
Abstract
Long-read sequencing, exemplified by PacBio, revolutionizes genomics, overcoming challenges like repetitive sequences. However, the high DNA requirement ( > 1 µg) is prohibitive for small organisms. We develop a low-input (100 ng), low-cost, and amplification-free library-generation method for PacBio sequencing (LILAP) using Tn5-based tagmentation and DNA circularization within one tube. We test LILAP with two Drosophila melanogaster individuals, and generate near-complete genomes, surpassing preexisting single-fly genomes. By analyzing variations in these two genomes, we characterize mutational processes: complex transpositions (transposon insertions together with extra duplications and/or deletions) prefer regions characterized by non-B DNA structures, and gene conversion of transposons occurs on both DNA and RNA levels. Concurrently, we generate two complete assemblies for the endosymbiotic bacterium Wolbachia in these flies and similarly detect transposon conversion. Thus, LILAP promises a broad PacBio sequencing adoption for not only mutational studies of flies and their symbionts but also explorations of other small organisms or precious samples.
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Affiliation(s)
- Hangxing Jia
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
| | - Shengjun Tan
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
| | - Yingao Cai
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yanyan Guo
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jieyu Shen
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Yaqiong Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Huijing Ma
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Qingzhu Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jinfeng Chen
- University of Chinese Academy of Sciences, Beijing, China
- State Key Laboratory of Integrated Management of Pest Insects and Rodents, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
| | - Gexia Qiao
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China
- University of Chinese Academy of Sciences, Beijing, China
| | - Jue Ruan
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, China.
| | - Yong E Zhang
- Key Laboratory of Zoological Systematics and Evolution, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
- University of Chinese Academy of Sciences, Beijing, China.
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2
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Tiedeman Z, Signor S. The transposable elements of the Drosophila serrata reference panel. Genome Biol Evol 2021; 13:6265467. [PMID: 33950180 PMCID: PMC8434751 DOI: 10.1093/gbe/evab100] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/30/2021] [Indexed: 11/13/2022] Open
Abstract
Transposable elements (TEs) are an important component of the complex genomic ecosystem. Understanding the tempo and mode of TE proliferation, that is whether it is in maintained in transposition selection balance, or is induced periodically by environmental stress or other factors, is important for understanding the evolution of organismal genomes through time. Although TEs have been characterized in individuals or limited samples, a true understanding of the population genetics of TEs, and therefore the tempo and mode of transposition, is still lacking. Here, we characterize the TE landscape in an important model Drosophila, Drosophila serrata using the D. serrata reference panel, which is comprised of 102 sequenced inbred genotypes. We annotate the families of TEs in the D. serrata genome and investigate variation in TE copy number between genotypes. We find that many TEs have low copy number in the population, but this varies by family and includes a single TE making up to 50% of the genome content of TEs. We find that some TEs proliferate in particular genotypes compared with population levels. In addition, we characterize variation in each TE family allowing copy number to vary in each genotype and find that some TEs have diversified very little between individuals suggesting recent spread. TEs are important sources of spontaneous mutations in Drosophila, making up a large fraction of the total number of mutations in particular genotypes. Understanding the dynamics of TEs within populations will be an important step toward characterizing the origin of variation within and between species.
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Affiliation(s)
- Zachery Tiedeman
- Department of Biological Sciences, North Dakota State University, Fargo, North Dakota, U.S.A
| | - Sarah Signor
- Department of Biological Sciences, North Dakota State University, Fargo, North Dakota, U.S.A
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3
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Yushkova E. Effects of ionizing radiation at Drosophila melanogaster with differently active hobo transposons. Int J Radiat Biol 2019; 95:1564-1572. [PMID: 31287364 DOI: 10.1080/09553002.2019.1642534] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Purpose: The role of transposable elements in formation of radiobiological effects is understudied and contradictory. The aim of this study was to investigate the response of Drosophila melanogaster to irradiation depending on the level of activity hobo transposons and the role of hobo transposons in formation of ionizing radiation late effects.Materials and methods: The individuals of Drosophila melanogaster with different level activity of hobo-elements were exposed to acute irradiation in doses of 1-100 Gy at early ontogenesis stages. The reaction of individuals to exposure was studied using the larvae survival rate, morphological parameters of reproduction system, DNA damage rate, and mutability of mini-white locus.Results: We found the pronounced linear deferred effects of irradiation for animals with a high activity level of full-size hobo copies. The radiosensitivity of individuals with a mean level of activity transposon was whether higher or did not differ from the radiosensitivity of animals with a low activity hobo.Conclusion: The obtained results suggest that full-size hobo-elements with a high activity level (less often with a mean activity level) are responsible for delayed deleterious irradiation effects.
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Affiliation(s)
- Elena Yushkova
- Institute of Biology of Komi Science Centre of the Ural Branch of the Russian Academy of Sciences, Syktyvkar, Russia
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4
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Solares EA, Chakraborty M, Miller DE, Kalsow S, Hall K, Perera AG, Emerson JJ, Hawley RS. Rapid Low-Cost Assembly of the Drosophila melanogaster Reference Genome Using Low-Coverage, Long-Read Sequencing. G3 (BETHESDA, MD.) 2018; 8:3143-3154. [PMID: 30018084 PMCID: PMC6169397 DOI: 10.1534/g3.118.200162] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2018] [Accepted: 07/03/2018] [Indexed: 12/27/2022]
Abstract
Accurate and comprehensive characterization of genetic variation is essential for deciphering the genetic basis of diseases and other phenotypes. A vast amount of genetic variation stems from large-scale sequence changes arising from the duplication, deletion, inversion, and translocation of sequences. In the past 10 years, high-throughput short reads have greatly expanded our ability to assay sequence variation due to single nucleotide polymorphisms. However, a recent de novo assembly of a second Drosophila melanogaster reference genome has revealed that short read genotyping methods miss hundreds of structural variants, including those affecting phenotypes. While genomes assembled using high-coverage long reads can achieve high levels of contiguity and completeness, concerns about cost, errors, and low yield have limited widespread adoption of such sequencing approaches. Here we resequenced the reference strain of D. melanogaster (ISO1) on a single Oxford Nanopore MinION flow cell run for 24 hr. Using only reads longer than 1 kb or with at least 30x coverage, we assembled a highly contiguous de novo genome. The addition of inexpensive paired reads and subsequent scaffolding using an optical map technology achieved an assembly with completeness and contiguity comparable to the D. melanogaster reference assembly. Comparison of our assembly to the reference assembly of ISO1 uncovered a number of structural variants (SVs), including novel LTR transposable element insertions and duplications affecting genes with developmental, behavioral, and metabolic functions. Collectively, these SVs provide a snapshot of the dynamics of genome evolution. Furthermore, our assembly and comparison to the D. melanogaster reference genome demonstrates that high-quality de novo assembly of reference genomes and comprehensive variant discovery using such assemblies are now possible by a single lab for under $1,000 (USD).
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Affiliation(s)
- Edwin A Solares
- Department of Ecology and Evolutionary Biology, University of California Irvine, CA
| | - Mahul Chakraborty
- Department of Ecology and Evolutionary Biology, University of California Irvine, CA
| | - Danny E Miller
- Stowers Institute for Medical Research, Kansas City, MO
- MD-PhD Physician Scientist Training Program, University of Kansas Medical Center, Kansas City, KS
| | - Shannon Kalsow
- Department of Ecology and Evolutionary Biology, University of California Irvine, CA
| | - Kate Hall
- Stowers Institute for Medical Research, Kansas City, MO
| | | | - J J Emerson
- Department of Ecology and Evolutionary Biology, University of California Irvine, CA
| | - R Scott Hawley
- Stowers Institute for Medical Research, Kansas City, MO
- Department of Molecular and Integrative Physiology, University of Kansas Medical Center, Kansas City, KS
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5
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Ryazansky S, Radion E, Mironova A, Akulenko N, Abramov Y, Morgunova V, Kordyukova MY, Olovnikov I, Kalmykova A. Natural variation of piRNA expression affects immunity to transposable elements. PLoS Genet 2017; 13:e1006731. [PMID: 28448516 PMCID: PMC5407775 DOI: 10.1371/journal.pgen.1006731] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 03/31/2017] [Indexed: 11/25/2022] Open
Abstract
In the Drosophila germline, transposable elements (TEs) are silenced by PIWI-interacting RNA (piRNA) that originate from distinct genomic regions termed piRNA clusters and are processed by PIWI-subfamily Argonaute proteins. Here, we explore the variation in the ability to restrain an alien TE in different Drosophila strains. The I-element is a retrotransposon involved in the phenomenon of I-R hybrid dysgenesis in Drosophila melanogaster. Genomes of R strains do not contain active I-elements, but harbour remnants of ancestral I-related elements. The permissivity to I-element activity of R females, called reactivity, varies considerably in natural R populations, indicating the existence of a strong natural polymorphism in defense systems targeting transposons. To reveal the nature of such polymorphisms, we compared ovarian small RNAs between R strains with low and high reactivity and show that reactivity negatively correlates with the ancestral I-element-specific piRNA content. Analysis of piRNA clusters containing remnants of I-elements shows increased expression of the piRNA precursors and enrichment by the Heterochromatin Protein 1 homolog, Rhino, in weak R strains, which is in accordance with stronger piRNA expression by these regions. To explore the nature of the differences in piRNA production, we focused on two R strains, weak and strong, and showed that the efficiency of maternal inheritance of piRNAs as well as the I-element copy number are very similar in both strains. At the same time, germline and somatic uni-strand piRNA clusters generate more piRNAs in strains with low reactivity, suggesting the relationship between the efficiency of primary piRNA production and variable response to TE invasions. The strength of adaptive genome defense is likely driven by naturally occurring polymorphisms in the rapidly evolving piRNA pathway proteins. We hypothesize that hyper-efficient piRNA production is contributing to elimination of a telomeric retrotransposon HeT-A, which we have observed in one particular transposon-resistant R strain. Transposon activity in the germline is suppressed by the PIWI-interacting RNA (piRNA) pathway. The resistance of natural Drosophila strains to transposon invasion varies considerably, but the nature of this variability is unknown. We discovered that natural variation in the efficiency of primary piRNA production in the germline causes dramatic differences in the susceptibility to expansion of a newly invaded transposon. A high level of piRNA production in the germline is achieved by increased expression of piRNA precursors. In one of the most transposon-resistant strains, increased content of primary piRNA is observed in both the germline and ovarian somatic cells. We suggest that polymorphisms in piRNA pathway factors are responsible for increased piRNA production. piRNA pathway proteins have been shown to be evolving rapidly under selective pressure. Our data are the first to describe a phenotype that might be caused by this kind of polymorphism. We also demonstrate a likely explanation as to why an overly active piRNA pathway can cause more harm than good in Drosophila: Highly efficient piRNA processing leads to elimination of domesticated telomeric retrotransposons essential for telomere elongation, an effect which has been observed in a natural strain that is extremely resistant to transposon invasion.
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Affiliation(s)
- Sergei Ryazansky
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Elizaveta Radion
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Anastasia Mironova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Natalia Akulenko
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Yuri Abramov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Valeriya Morgunova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Maria Y. Kordyukova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Ivan Olovnikov
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
| | - Alla Kalmykova
- Institute of Molecular Genetics, Russian Academy of Sciences, Moscow, Russia
- * E-mail:
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6
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Rahman R, Chirn GW, Kanodia A, Sytnikova YA, Brembs B, Bergman CM, Lau NC. Unique transposon landscapes are pervasive across Drosophila melanogaster genomes. Nucleic Acids Res 2015; 43:10655-72. [PMID: 26578579 PMCID: PMC4678822 DOI: 10.1093/nar/gkv1193] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2015] [Accepted: 10/24/2015] [Indexed: 01/01/2023] Open
Abstract
To understand how transposon landscapes (TLs) vary across animal genomes, we describe a new method called the Transposon Insertion and Depletion AnaLyzer (TIDAL) and a database of >300 TLs in Drosophila melanogaster (TIDAL-Fly). Our analysis reveals pervasive TL diversity across cell lines and fly strains, even for identically named sub-strains from different laboratories such as the ISO1 strain used for the reference genome sequence. On average, >500 novel insertions exist in every lab strain, inbred strains of the Drosophila Genetic Reference Panel (DGRP), and fly isolates in the Drosophila Genome Nexus (DGN). A minority (<25%) of transposon families comprise the majority (>70%) of TL diversity across fly strains. A sharp contrast between insertion and depletion patterns indicates that many transposons are unique to the ISO1 reference genome sequence. Although TL diversity from fly strains reaches asymptotic limits with increasing sequencing depth, rampant TL diversity causes unsaturated detection of TLs in pools of flies. Finally, we show novel transposon insertions negatively correlate with Piwi-interacting RNA (piRNA) levels for most transposon families, except for the highly-abundant roo retrotransposon. Our study provides a useful resource for Drosophila geneticists to understand how transposons create extensive genomic diversity in fly cell lines and strains.
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Affiliation(s)
- Reazur Rahman
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Gung-wei Chirn
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Abhay Kanodia
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Yuliya A Sytnikova
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
| | - Björn Brembs
- Institute of Zoology, Universität Regensburg, Regensburg, Germany
| | - Casey M Bergman
- Faculty of Life Sciences, University of Manchester, Manchester M21 0RG, UK
| | - Nelson C Lau
- Department of Biology and Rosenstiel Basic Medical Science Research Center, Brandeis University, Waltham, MA 02454, USA
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7
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Zakharenko LP. Comparison of methods for the determination of the transposition rate of mobile elements. Mob Genet Elements 2015; 5:60-62. [PMID: 26442186 PMCID: PMC4588159 DOI: 10.1080/2159256x.2015.1052895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2015] [Revised: 04/30/2015] [Accepted: 05/08/2015] [Indexed: 10/28/2022] Open
Abstract
There is wide-spread interest in understanding the rate of transposable element movement within populations and between species. A recent study using interprecific crosses between D. buzzatii and D. koepferae indicated that transposition rates in hybrids may be quite high. However, we suggest caution should be taken in this interpretation since AFLP methods to detect transposition events may lead to overestimated rate estimates. Comparative analyses of genome instability received by different methods suggest that transposition rates can be higher in intraspecific crosses compared to interspecific crosses.
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8
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Zakharenko LP, Ignatenko OM. The rate of transposition and the specificity of transposable element insertions are not sufficient to cause gonadal dysgenesis in Drosophila melanogaster. RUSS J GENET+ 2014. [DOI: 10.1134/s1022795414110167] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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9
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Zakharenko LP, Karpova EK, Rauschenbach IY. P-M hybrid dysgenesis affects juvenile hormone metabolism in Drosophila melanogaster females. RUSS J GENET+ 2014. [DOI: 10.1134/s1022795414060143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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10
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Xie W, Donohue RC, Birchler JA. Quantitatively increased somatic transposition of transposable elements in Drosophila strains compromised for RNAi. PLoS One 2013; 8:e72163. [PMID: 23940807 PMCID: PMC3733903 DOI: 10.1371/journal.pone.0072163] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2013] [Accepted: 07/07/2013] [Indexed: 11/19/2022] Open
Abstract
In Drosophila melanogaster, small RNAs homologous to transposable elements (TEs) are of two types: piRNA (piwi-interacting RNA) with size 23-29nt and siRNA (small interfering RNA) with size 19-22nt. The siRNA pathway is suggested to silence TE activities in somatic tissues based on TE expression profiles, but direct evidence of transposition is lacking. Here we developed an efficient FISH (fluorescence in Situ hybridization) based method for polytene chromosomes from larval salivary glands to reveal new TE insertions. Analysis of the LTR-retrotransposon 297 and the non-LTR retroposon DOC shows that in the argonaut 2 (Ago2) and Dicer 2 (Dcr2) mutant strains, new transposition events are much more frequent than in heterozygous strains or wild type strains. The data demonstrate that the siRNA pathway represses TE transposition in somatic cells. Nevertheless, we found that loss of one functional copy of Ago2 or Dcr2 increases somatic transpositions of the elements at a lower level depending on the genetic background, suggesting a quantitative role for RNAi core components on mutation frequency.
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Affiliation(s)
- Weiwu Xie
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
| | - Ryan C. Donohue
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
| | - James A. Birchler
- Division of Biological Sciences, University of Missouri, Columbia, Missouri, United States of America
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11
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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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12
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Rozhkov NV, Zelentsova ES, Shostak NG, Evgen'ev MB. Expression of Drosophila virilis retroelements and role of small RNAs in their intrastrain transposition. PLoS One 2011; 6:e21883. [PMID: 21779346 PMCID: PMC3136932 DOI: 10.1371/journal.pone.0021883] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2011] [Accepted: 06/10/2011] [Indexed: 11/18/2022] Open
Abstract
Transposition of two retroelements (Ulysses and Penelope) mobilized in the course of hybrid dysgenesis in Drosophila virilis has been investigated by in situ hybridization on polytene chromosomes in two D. virilis strains of different cytotypes routinely used to get dysgenic progeny. The analysis has been repeatedly performed over the last two decades, and has revealed transpositions of Penelope in one of the strains, while, in the other strain, the LTR-containing element Ulysses was found to be transpositionally active. The gypsy retroelement, which has been previously shown to be transpositionally inactive in D. virilis strains, was also included in the analysis. Whole mount is situ hybridization with the ovaries revealed different subcellular distribution of the transposable elements transcripts in the strains studied. Ulysses transpositions occur only in the strain where antisense piRNAs homologous to this TE are virtually absent and the ping-pong amplification loop apparently does not take place. On the other hand small RNAs homologous to Penelope found in the other strain, belong predominantly to the siRNA category (21nt), and consist of sense and antisense species observed in approximately equal proportion. The number of Penelope copies in the latter strain has significantly increased during the last decades, probably because Penelope-derived siRNAs are not maternally inherited, while the low level of Penelope-piRNAs, which are faithfully transmitted from mother to the embryo, is not sufficient to silence this element completely. Therefore, we speculate that intrastrain transposition of the three retroelements studied is controlled predominantly at the post-transcriptional level.
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13
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Moschetti R, Dimitri P, Caizzi R, Junakovic N. Genomic instability of I elements of Drosophila melanogaster in absence of dysgenic crosses. PLoS One 2010; 5. [PMID: 20957225 PMCID: PMC2949383 DOI: 10.1371/journal.pone.0013142] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2010] [Accepted: 08/10/2010] [Indexed: 11/18/2022] Open
Abstract
Retrotranspostion of I factors in the female germline of Drosophila melanogaster is responsible for the so called I-R hybrid dysgenesis, a phenomenon that produces a broad spectrum of genetic abnormalities including reduced fertility, increased frequency of mutations and chromosome loss. Transposition of I factor depends on cellular conditions that are established in the oocytes of the reactive females and transmitted to their daughters. The so-called reactivity is a cellular state that may exhibit variable levels of expression and represents a permissive condition for I transposition at high levels. Defective I elements have been proposed to be the genetic determinants of reactivity and, through their differential expression, to modulate transposition of active copies in somatic and/or germ line cells. Recently, control of transposable element activity in the germ line has been found to depend on pi-RNAs, small repressive RNAs interacting with Piwi-family proteins and derived from larger transposable elements (TE)-derived primary transcripts. In particular, maternally transmitted I-element piRNAs originating from the 42AB region of polytene chromosomes were found to be involved in control of I element mobility. In the present work, we use a combination of cytological and molecular approaches to study the activity of I elements in three sublines of the inducer y; cn bw; sp isogenic strain and in dysgenic and non-dysgenic genetic backgrounds. Overall, the results of FISH and Southern blotting experiments clearly show that I elements are highly unstable in the Montpellier subline in the absence of classical dysgenic conditions. Such instability appears to be correlated to the amount of 5' and 3' I element transcripts detected by quantitative and real-time RT-PCR. The results of this study indicate that I elements can be highly active in the absence of a dysgenic crosses. Moreover, in the light of our results caution should be taken to assimilate the genomic annotation data on transposable elements to all y; cn bw sp sublines.
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Affiliation(s)
- Roberta Moschetti
- Dipartimento di Genetica e Microbiologia, Università di Bari “Aldo Moro”, Bari, Italy
| | - Patrizio Dimitri
- Dipartimento di Genetica e Biologia Molecolare, Charles Darwin, Roma, Italy
- * E-mail:
| | - Ruggiero Caizzi
- Dipartimento di Genetica e Microbiologia, Università di Bari “Aldo Moro”, Bari, Italy
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The Importance of Transpositions and Recombination to Genome Instability According hobo-Element Distribution Pattern in Completely Sequenced Genome of Drosophila melanogaster. Evol Biol 2009. [DOI: 10.1007/978-3-642-00952-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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