1
|
Kutnowski N, Ghanim GE, Lee Y, Rio DC. Activity of zebrafish THAP9 transposase and zebrafish P element-like transposons. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.22.586318. [PMID: 38562726 PMCID: PMC10983969 DOI: 10.1101/2024.03.22.586318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/04/2024]
Abstract
Transposable elements are mobile DNA segments that are found ubiquitously across the three domains of life. One family of transposons, called P elements, were discovered in the fruit fly Drosophila melanogaster. Since their discovery, P element transposase-homologous genes (called THAP-domain containing 9 or THAP9) have been discovered in other animal genomes. Here, we show that the zebrafish (Danio rerio) genome contains both an active THAP9 transposase (zfTHAP9) and mobile P-like transposable elements (called Pdre). zfTHAP9 transposase can excise one of its own elements (Pdre2) and Drosophila P elements. Drosophila P element transposase (DmTNP) is also able to excise the zebrafish Pdre2 element, even though it's distinct from the Drosophila P element. However, zfTHAP9 cannot transpose Pdre2 or Drosophila P elements, indicating partial transposase activity. Characterization of the N-terminal THAP DNA binding domain of zfTHAP9 shows distinct DNA binding site preferences from DmTNP and mutation of the zfTHAP9, based on known mutations in DmTNP, generated a hyperactive protein,. These results define an active vertebrate THAP9 transposase that can act on the endogenous zebrafish Pdre and Drosophila P elements.
Collapse
Affiliation(s)
- Nitzan Kutnowski
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| | - George E Ghanim
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| | - Yeon Lee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| | - Donald C Rio
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA, USA
| |
Collapse
|
2
|
Abraham LN, Oggenfuss U, Croll D. Population-level transposable element expression dynamics influence trait evolution in a fungal crop pathogen. mBio 2024; 15:e0284023. [PMID: 38349152 PMCID: PMC10936205 DOI: 10.1128/mbio.02840-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 01/22/2024] [Indexed: 03/14/2024] Open
Abstract
The rapid adaptive evolution of microbes is driven by strong selection pressure acting on genetic variation. How adaptive genetic variation is generated within species and how such variation influences phenotypic trait expression is often not well understood though. We focused on the recent activity of transposable elements (TEs) using deep population genomics and transcriptomics analyses of a fungal plant pathogen with a highly active content of TEs in the genome. Zymoseptoria tritici causes one of the most damaging diseases on wheat, with recent adaptation to the host and environment being facilitated by TE-associated mutations. We obtained genomic and RNA-sequencing data from 146 isolates collected from a single wheat field. We established a genome-wide map of TE insertion polymorphisms in the population by analyzing recent TE insertions among individuals. We quantified the locus-specific transcription of individual TE copies and found considerable population variation at individual TE loci in the population. About 20% of all TE copies show transcription in the genome suggesting that genomic defenses such as repressive epigenetic marks and repeat-induced polymorphisms are at least partially ineffective at preventing the proliferation of TEs in the genome. A quarter of recent TE insertions are associated with expression variation of neighboring genes providing broad potential to influence trait expression. We indeed found that TE insertions are likely responsible for variation in virulence on the host and potentially diverse components of secondary metabolite production. Our large-scale transcriptomics study emphasizes how TE-derived polymorphisms segregate even in individual microbial populations and can broadly underpin trait variation in pathogens.IMPORTANCEPathogens can rapidly adapt to new hosts, antimicrobials, or changes in the environment. Adaptation arises often from mutations in the genome; however, how such variation is generated remains poorly understood. We investigated the most dynamic regions of the genome of Zymoseptoria tritici, a major fungal pathogen of wheat. We focused on the transcription of transposable elements. A large proportion of the transposable elements not only show signatures of potential activity but are also variable within a single population of the pathogen. We find that this variation in activity is likely influencing many important traits of the pathogen. Hence, our work provides insights into how a microbial species can adapt over the shortest time periods based on the activity of transposable elements.
Collapse
Affiliation(s)
- Leen Nanchira Abraham
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Ursula Oggenfuss
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| | - Daniel Croll
- Laboratory of Evolutionary Genetics, Institute of Biology, University of Neuchâtel, Neuchâtel, Switzerland
| |
Collapse
|
3
|
Pang LY, DeLuca S, Zhu H, Urban JM, Spradling AC. Chromatin and gene expression changes during female Drosophila germline stem cell development illuminate the biology of highly potent stem cells. eLife 2023; 12:RP90509. [PMID: 37831064 PMCID: PMC10575629 DOI: 10.7554/elife.90509] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/14/2023] Open
Abstract
Highly potent animal stem cells either self renew or launch complex differentiation programs, using mechanisms that are only partly understood. Drosophila female germline stem cells (GSCs) perpetuate without change over evolutionary time and generate cystoblast daughters that develop into nurse cells and oocytes. Cystoblasts initiate differentiation by generating a transient syncytial state, the germline cyst, and by increasing pericentromeric H3K9me3 modification, actions likely to suppress transposable element activity. Relatively open GSC chromatin is further restricted by Polycomb repression of testis or somatic cell-expressed genes briefly active in early female germ cells. Subsequently, Neijre/CBP and Myc help upregulate growth and reprogram GSC metabolism by altering mitochondrial transmembrane transport, gluconeogenesis, and other processes. In all these respects GSC differentiation resembles development of the totipotent zygote. We propose that the totipotent stem cell state was shaped by the need to resist transposon activity over evolutionary timescales.
Collapse
Affiliation(s)
- Liang-Yu Pang
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Steven DeLuca
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Haolong Zhu
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - John M Urban
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| | - Allan C Spradling
- Howard Hughes Medical Institute, Carnegie Institution for ScienceBaltimoreUnited States
| |
Collapse
|
4
|
Munasinghe M, Springer N, Brandvain Y. Critical role of insertion preference for invasion trajectory of transposons. Evolution 2023; 77:2173-2185. [PMID: 37519088 DOI: 10.1093/evolut/qpad128] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2022] [Revised: 05/01/2023] [Accepted: 07/24/2023] [Indexed: 08/01/2023]
Abstract
It is unclear how mobile DNA sequences (transposable elements, hereafter TEs) invade eukaryotic genomes and reach stable copy numbers, as transposition can decrease host fitness. This challenge is particularly stark early in the invasion of a TE family at which point hosts may lack the specialized machinery to repress the spread of these TEs. One possibility (in addition to the evolution of host regulation of TEs) is that TE families may evolve to preferentially insert into chromosomal regions that are less likely to impact host fitness. This may allow the mean TE copy number to grow while minimizing the risk for host population extinction. To test this, we constructed simulations to explore how the transposition probability and insertion preference of a TE family influence the evolution of mean TE copy number and host population size, allowing for extinction. We find that the effect of a TE family's insertion preference depends on a host's ability to regulate this TE family. Without host repression, a neutral insertion preference increases the frequency of and decreases the time to population extinction. With host repression, a preference for neutral insertions minimizes the cumulative deleterious load, increases population fitness, and, ultimately, avoids triggering an extinction vortex.
Collapse
Affiliation(s)
- Manisha Munasinghe
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, United States
| | - Nathan Springer
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, United States
| | - Yaniv Brandvain
- Department of Plant and Microbial Biology, University of Minnesota, St. Paul, MN, United States
- Department of Ecology, Evolution and Behavior, University of Minnesota, St. Paul, MN, United States
| |
Collapse
|
5
|
Langmüller AM, Nolte V, Dolezal M, Schlötterer C. The genomic distribution of transposable elements is driven by spatially variable purifying selection. Nucleic Acids Res 2023; 51:9203-9213. [PMID: 37560917 PMCID: PMC10516647 DOI: 10.1093/nar/gkad635] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Revised: 07/10/2023] [Accepted: 07/18/2023] [Indexed: 08/11/2023] Open
Abstract
It is widely accepted that the genomic distribution of transposable elements (TEs) mainly reflects the outcome of purifying selection and insertion bias (1). Nevertheless, the relative importance of these two evolutionary forces could not be tested thoroughly. Here, we introduce an experimental system, which allows separating purifying selection from TE insertion bias. We used experimental evolution to study the TE insertion patterns in Drosophila simulans founder populations harboring 1040 insertions of an active P-element. After 10 generations at a large population size, we detected strong selection against P-element insertions. The exception were P-element insertions in genomic regions for which a strong insertion bias has been proposed (2-4). Because recurrent P-element insertions cannot explain this pattern, we conclude that purifying selection, with variable strength along the chromosomes, is the major determinant of the genomic distribution of P-elements. Genomic regions with relaxed purifying selection against P-element insertions exhibit normal levels of purifying selection against base substitutions. This suggests that different types of purifying selection operate on base substitutions and P-element insertions. Our results highlight the power of experimental evolution to understand basic evolutionary processes, which are difficult to infer from patterns of natural variation alone.
Collapse
Affiliation(s)
- Anna M Langmüller
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
- Vienna Graduate School of Population Genetics, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Viola Nolte
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Marlies Dolezal
- Plattform Bioinformatik und Biostatistik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Vienna, Austria
| | - Christian Schlötterer
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| |
Collapse
|
6
|
Son W, Chung KW. Targeted recombination of homologous chromosomes using CRISPR-Cas9. FEBS Open Bio 2023; 13:1658-1666. [PMID: 37462508 PMCID: PMC10476559 DOI: 10.1002/2211-5463.13676] [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: 03/07/2023] [Revised: 06/22/2023] [Accepted: 07/17/2023] [Indexed: 07/28/2023] Open
Abstract
CRISPR mutagenesis is an efficient way to disrupt specific target genes in many model organisms. We previously devised a targeted CRISPR recombination method to generate intragenic recombinants of alleles in Drosophila. Here, we assessed the applicability of CRISPR targeting-induced recombination to different genetic loci. We compared the ectopic recombination rates in the male germline by CRISPR targeting at two neighboring genetic loci within the genomic region that consists of the repressed chromatin domain of the Lobe gene, and the transcriptionally active domain of PRAS40. Targeting around the transcription initiation of PRAS40 resulted in higher recombination rates of homologous chromosomes than targeting at the Lobe intron. Based on the efficient homologous recombination by CRISPR targeting observed around transcriptionally active loci, we further investigated targeted recombination between P-elements that are inserted at different genomic locations. Male recombination by CRISPR targeting of P-elements located proximally and distally to the ebony gene produced recombinants deficient for the intervening region of ebony transcription. Taken together, we suggest that targeted homologous recombination by CRISPR targeting may have specific genetic applications, such as generation of allelic combinations or chromosomal variations.
Collapse
Affiliation(s)
- Wonseok Son
- Department of Biological Sciences and BK21 Team for Field‐oriented BioCore Human Resources DevelopmentKongju National UniversityGongjuSouth Korea
| | - Ki Wha Chung
- Department of Biological Sciences and BK21 Team for Field‐oriented BioCore Human Resources DevelopmentKongju National UniversityGongjuSouth Korea
| |
Collapse
|
7
|
Wang L, Zhang S, Hadjipanteli S, Saiz L, Nguyen L, Silva E, Kelleher E. P-element invasion fuels molecular adaptation in laboratory populations of Drosophila melanogaster. Evolution 2023; 77:980-994. [PMID: 36749648 PMCID: PMC10078945 DOI: 10.1093/evolut/qpad017] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2022] [Revised: 01/02/2023] [Accepted: 02/06/2023] [Indexed: 02/08/2023]
Abstract
Transposable elements (TEs) are mobile genetic parasites that frequently invade new host genomes through horizontal transfer. Invading TEs often exhibit a burst of transposition, followed by reduced transposition rates as repression evolves in the host. We recreated the horizontal transfer of P-element DNA transposons into a Drosophila melanogaster host and followed the expansion of TE copies and evolution of host repression in replicate laboratory populations reared at different temperatures. We observed that while populations maintained at high temperatures rapidly go extinct after TE invasion, those maintained at lower temperatures persist, allowing for TE spread and the evolution of host repression. We also surprisingly discovered that invaded populations experienced recurrent insertion of P-elements into a specific long non-coding RNA, lncRNA:CR43651, and that these insertion alleles are segregating at unusually high frequency in experimental populations, indicative of positive selection. We propose that, in addition to driving the evolution of repression, transpositional bursts of invading TEs can drive molecular adaptation.
Collapse
Affiliation(s)
- Luyang Wang
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Shuo Zhang
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Savana Hadjipanteli
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Lorissa Saiz
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Lisa Nguyen
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Efren Silva
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| | - Erin Kelleher
- Department of Biology and Biochemistry, University of Houston, Houston, TX, United States
| |
Collapse
|
8
|
Cao J, Yu T, Xu B, Hu Z, Zhang XO, Theurkauf W, Weng Z. Epigenetic and chromosomal features drive transposon insertion in Drosophila melanogaster. Nucleic Acids Res 2023; 51:2066-2086. [PMID: 36762470 PMCID: PMC10018349 DOI: 10.1093/nar/gkad054] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2022] [Revised: 01/12/2023] [Accepted: 02/07/2023] [Indexed: 02/11/2023] Open
Abstract
Transposons are mobile genetic elements prevalent in the genomes of most species. The distribution of transposons within a genome reflects the actions of two opposing processes: initial insertion site selection, and selective pressure from the host. By analyzing whole-genome sequencing data from transposon-activated Drosophila melanogaster, we identified 43 316 de novo and 237 germline insertions from four long-terminal-repeat (LTR) transposons, one LINE transposon (I-element), and one DNA transposon (P-element). We found that all transposon types favored insertion into promoters de novo, but otherwise displayed distinct insertion patterns. De novo and germline P-element insertions preferred replication origins, often landing in a narrow region around transcription start sites and in regions of high chromatin accessibility. De novo LTR transposon insertions preferred regions with high H3K36me3, promoters and exons of active genes; within genes, LTR insertion frequency correlated with gene expression. De novo I-element insertion density increased with distance from the centromere. Germline I-element and LTR transposon insertions were depleted in promoters and exons, suggesting strong selective pressure to remove transposons from functional elements. Transposon movement is associated with genome evolution and disease; therefore, our results can improve our understanding of genome and disease biology.
Collapse
Affiliation(s)
| | - Tianxiong Yu
- Correspondence may also be addressed to Tianxiong Yu. Tel: +1 774 641 0409; Fax: +1 508 856 0017;
| | - Bo Xu
- The School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Zhongren Hu
- The School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - Xiao-ou Zhang
- The School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
| | - William E Theurkauf
- Program in Molecular Medicine, University of Massachusetts Chan Medical School, Worcester, MA, USA
| | - Zhiping Weng
- To whom correspondence should be addressed. Tel: +1 508 856 8866; Fax: +1 508 856 0017;
| |
Collapse
|
9
|
Moeckel C, Zaravinos A, Georgakopoulos-Soares I. Strand Asymmetries Across Genomic Processes. Comput Struct Biotechnol J 2023; 21:2036-2047. [PMID: 36968020 PMCID: PMC10030826 DOI: 10.1016/j.csbj.2023.03.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2023] [Revised: 03/08/2023] [Accepted: 03/08/2023] [Indexed: 03/12/2023] Open
Abstract
Across biological systems, a number of genomic processes, including transcription, replication, DNA repair, and transcription factor binding, display intrinsic directionalities. These directionalities are reflected in the asymmetric distribution of nucleotides, motifs, genes, transposon integration sites, and other functional elements across the two complementary strands. Strand asymmetries, including GC skews and mutational biases, have shaped the nucleotide composition of diverse organisms. The investigation of strand asymmetries often serves as a method to understand underlying biological mechanisms, including protein binding preferences, transcription factor interactions, retrotransposition, DNA damage and repair preferences, transcription-replication collisions, and mutagenesis mechanisms. Research into this subject also enables the identification of functional genomic sites, such as replication origins and transcription start sites. Improvements in our ability to detect and quantify DNA strand asymmetries will provide insights into diverse functionalities of the genome, the contribution of different mutational mechanisms in germline and somatic mutagenesis, and our knowledge of genome instability and evolution, which all have significant clinical implications in human disease, including cancer. In this review, we describe key developments that have been made across the field of genomic strand asymmetries, as well as the discovery of associated mechanisms.
Collapse
Affiliation(s)
- Camille Moeckel
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Apostolos Zaravinos
- Department of Life Sciences, European University Cyprus, Diogenis Str., 6, Nicosia 2404, Cyprus
- Cancer Genetics, Genomics and Systems Biology laboratory, Basic and Translational Cancer Research Center (BTCRC), Nicosia 1516, Cyprus
- Corresponding author at: Department of Life Sciences, European University Cyprus, Diogenis Str., 6, Nicosia 2404, Cyprus.
| | - Ilias Georgakopoulos-Soares
- Institute for Personalized Medicine, Department of Biochemistry and Molecular Biology, The Pennsylvania State University College of Medicine, Hershey, PA, USA
- Corresponding author.
| |
Collapse
|
10
|
Lama J, Srivastav S, Tasnim S, Hubbard D, Hadjipanteli S, Smith BR, Macdonald SJ, Green L, Kelleher ES. Genetic variation in P-element dysgenic sterility is associated with double-strand break repair and alternative splicing of TE transcripts. PLoS Genet 2022; 18:e1010080. [PMID: 36477699 PMCID: PMC9762592 DOI: 10.1371/journal.pgen.1010080] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 12/19/2022] [Accepted: 11/02/2022] [Indexed: 12/12/2022] Open
Abstract
The germline mobilization of transposable elements (TEs) by small RNA mediated silencing pathways is conserved across eukaryotes and critical for ensuring the integrity of gamete genomes. However, genomes are recurrently invaded by novel TEs through horizontal transfer. These invading TEs are not targeted by host small RNAs, and their unregulated activity can cause DNA damage in germline cells and ultimately lead to sterility. Here we use hybrid dysgenesis-a sterility syndrome of Drosophila caused by transposition of invading P-element DNA transposons-to uncover host genetic variants that modulate dysgenic sterility. Using a panel of highly recombinant inbred lines of Drosophila melanogaster, we identified two linked quantitative trait loci (QTL) that determine the severity of dysgenic sterility in young and old females, respectively. We show that ovaries of fertile genotypes exhibit increased expression of splicing factors that suppress the production of transposase encoding transcripts, which likely reduces the transposition rate and associated DNA damage. We also show that fertile alleles are associated with decreased sensitivity to double-stranded breaks and enhanced DNA repair, explaining their ability to withstand high germline transposition rates. Together, our work reveals a diversity of mechanisms whereby host genotype modulates the cost of an invading TE, and points to genetic variants that were likely beneficial during the P-element invasion.
Collapse
Affiliation(s)
- Jyoti Lama
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Satyam Srivastav
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America
| | - Sadia Tasnim
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Donald Hubbard
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Savana Hadjipanteli
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Brittny R. Smith
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Stuart J. Macdonald
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas, United States of America
| | - Llewellyn Green
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| | - Erin S. Kelleher
- Department of Biology and Biochemistry, University of Houston, Houston, Texas, United States of America
| |
Collapse
|
11
|
Lee Y, Ha U, Moon S. Ongoing endeavors to detect mobilization of transposable elements. BMB Rep 2022. [PMID: 35725016 PMCID: PMC9340088 DOI: 10.5483/bmbrep.2022.55.7.088] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Transposable elements (TEs) are DNA sequences capable of mobilization from one location to another in the genome. Since the discovery of ‘Dissociation (Dc) locus’ by Barbara McClintock in maize (1), mounting evidence in the era of genomics indicates that a significant fraction of most eukaryotic genomes is composed of TE sequences, involving in various aspects of biological processes such as development, physiology, diseases and evolution. Although technical advances in genomics have discovered numerous functional impacts of TE across species, our understanding of TEs is still ongoing process due to challenges resulted from complexity and abundance of TEs in the genome. In this mini-review, we briefly summarize biology of TEs and their impacts on the host genome, emphasizing importance of understanding TE landscape in the genome. Then, we introduce recent endeavors especially in vivo retrotransposition assays and long read sequencing technology for identifying de novo insertions/TE polymorphism, which will broaden our knowledge of extraordinary relationship between genomic cohabitants and their host.
Collapse
Affiliation(s)
- Yujeong Lee
- Department of Biological Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Una Ha
- Department of Biological Sciences, Kangwon National University, Chuncheon 24341, Korea
| | - Sungjin Moon
- Department of Biological Sciences, Kangwon National University, Chuncheon 24341, Korea
| |
Collapse
|
12
|
Chang NC, Rovira Q, Wells J, Feschotte C, Vaquerizas JM. Zebrafish transposable elements show extensive diversification in age, genomic distribution, and developmental expression. Genome Res 2022; 32:1408-1423. [PMID: 34987056 PMCID: PMC9341512 DOI: 10.1101/gr.275655.121] [Citation(s) in RCA: 31] [Impact Index Per Article: 15.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Accepted: 12/30/2021] [Indexed: 12/02/2022]
Abstract
There is considerable interest in understanding the effect of transposable elements (TEs) on embryonic development. Studies in humans and mice are limited by the difficulty of working with mammalian embryos and by the relative scarcity of active TEs in these organisms. The zebrafish is an outstanding model for the study of vertebrate development, and over half of its genome consists of diverse TEs. However, zebrafish TEs remain poorly characterized. Here we describe the demography and genomic distribution of zebrafish TEs and their expression throughout embryogenesis using bulk and single-cell RNA sequencing data. These results reveal a highly dynamic genomic ecosystem comprising nearly 2000 distinct TE families, which vary in copy number by four orders of magnitude and span a wide range of ages. Longer retroelements tend to be retained in intergenic regions, whereas short interspersed nuclear elements (SINEs) and DNA transposons are more frequently found nearby or within genes. Locus-specific mapping of TE expression reveals extensive TE transcription during development. Although two-thirds of TE transcripts are likely driven by nearby gene promoters, we still observe stage- and tissue-specific expression patterns in self-regulated TEs. Long terminal repeat (LTR) retroelements are most transcriptionally active immediately following zygotic genome activation, whereas DNA transposons are enriched among transcripts expressed in later stages of development. Single-cell analysis reveals several endogenous retroviruses expressed in specific somatic cell lineages. Overall, our study provides a valuable resource for using zebrafish as a model to study the impact of TEs on vertebrate development.
Collapse
Affiliation(s)
- Ni-Chen Chang
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA
| | - Quirze Rovira
- Max Planck Institute for Molecular Biomedicine, 48149 Muenster, Germany
| | - Jonathan Wells
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850, USA
| | - Juan M Vaquerizas
- Max Planck Institute for Molecular Biomedicine, 48149 Muenster, Germany
- MRC London Institute of Medical Sciences, London W12 0NN, United Kingdom
- Institute of Clinical Sciences, Faculty of Medicine, Imperial College London, London W12 0NN, United Kingdom
| |
Collapse
|
13
|
Kofler R, Nolte V, Schlötterer C. The transposition rate has little influence on the plateauing level of the P-element. Mol Biol Evol 2022; 39:6613335. [PMID: 35731857 PMCID: PMC9254008 DOI: 10.1093/molbev/msac141] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The popular trap model assumes that the invasions of transposable elements (TEs) in mammals and invertebrates are stopped by piRNAs that emerge after insertion of the TE into a piRNA cluster. It remains, however, still unclear which factors influence the dynamics of TE invasions. The activity of the TE (i.e., transposition rate) is one frequently discussed key factor. Here we take advantage of the temperature-dependent activity of the P-element, a widely studied eukaryotic TE, to test how TE activity affects the dynamics of a TE invasion. We monitored P-element invasion dynamics in experimental Drosophila simulans populations at hot and cold culture conditions. Despite marked differences in transposition rates, the P-element reached very similar copy numbers at both temperatures. The reduction of the insertion rate upon approaching the copy number plateau was accompanied by similar amounts of piRNAs against the P-element at both temperatures. Nevertheless, we also observed fewer P-element insertions in piRNA clusters than expected, which is not compatible with a simple trap model. The ping-pong cycle, which degrades TE transcripts, becomes typically active after the copy number plateaued. We generated a model, with few parameters, that largely captures the observed invasion dynamics. We conclude that the transposition rate has at the most only a minor influence on TE abundance, but other factors, such as paramutations or selection against TE insertions are shaping the TE composition.
Collapse
Affiliation(s)
- Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Viola Nolte
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| | - Christian Schlötterer
- Institut für Populationsgenetik, Vetmeduni Vienna, Veterinärplatz 1, 1210 Wien, Austria
| |
Collapse
|
14
|
Gao D, Caspersen AM, Hu G, Bockelman HE, Chen X. A Novel Mutator-Like Transposable Elements With Unusual Structure and Recent Transpositions in Barley ( Hordeum vulgare). FRONTIERS IN PLANT SCIENCE 2022; 13:904619. [PMID: 35677233 PMCID: PMC9168764 DOI: 10.3389/fpls.2022.904619] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
Mutator-like transposable elements (MULEs) represent a unique superfamily of DNA transposons as they can capture host genes and cause higher frequency of mutations in some eukaryotes. Despite their essential roles in plant evolution and functional genomics, MULEs are not fully understood yet in many important crops including barley (Hordeum vulgare). In this study, we analyzed the barley genome and identified a new mutator transposon Hvu_Abermu. This transposon is present at extremely high copy number in barley and shows unusual structure as it contains three open reading frames (ORFs) including one ORF (ORF1) encoding mutator transposase protein and one ORF (ORFR) showing opposite transcriptional orientation. We identified homologous sequences of Hvu_Abermu in both monocots and dicots and grouped them into a large mutator family named Abermu. Abermu transposons from different species share significant sequence identity, but they exhibit distinct sequence structures. Unlike the transposase proteins which are highly conserved between Abermu transposons from different organisms, the ORFR-encoded proteins are quite different from distant species. Phylogenetic analysis indicated that Abermu transposons shared closer evolutionary relationships with the maize MuDR transposon than other reported MULEs. We also found phylogenetic incongruence for the Abermu transposons identified in rice and its wild species implying the possibility of horizontal transfer of transposon. Further comparison indicated that over 200 barley genes contain Abermu-related sequences. We analyzed the barley pan genomes and detected polymorphic Hvu_Abermu transposons between the sequenced 23 wild and cultivated barley genomes. Our efforts identified a novel mutator transposon and revealed its recent transposition activity, which may help to develop genetic tools for barley and other crops.
Collapse
Affiliation(s)
- Dongying Gao
- Small Grains and Potato Germplasm Research Unit, USDA-ARS, Aberdeen, ID, United States
| | - Ann M. Caspersen
- Small Grains and Potato Germplasm Research Unit, USDA-ARS, Aberdeen, ID, United States
| | - Gongshe Hu
- Small Grains and Potato Germplasm Research Unit, USDA-ARS, Aberdeen, ID, United States
| | - Harold E. Bockelman
- Small Grains and Potato Germplasm Research Unit, USDA-ARS, Aberdeen, ID, United States
| | - Xianming Chen
- Wheat Health, Genetics, and Quality Research Unit, USDA-ARS, Pullman, WA, United States
| |
Collapse
|
15
|
Catlin NS, Josephs EB. The important contribution of transposable elements to phenotypic variation and evolution. CURRENT OPINION IN PLANT BIOLOGY 2022; 65:102140. [PMID: 34883307 DOI: 10.1016/j.pbi.2021.102140] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2021] [Revised: 10/04/2021] [Accepted: 10/13/2021] [Indexed: 06/13/2023]
Abstract
Transposable elements (TEs) are responsible for significant genomic variation in plants. Our understanding of the evolutionary forces shaping TE polymorphism has lagged behind other mutations because of the difficulty of accurately identifying TE polymorphism in short-read population genomic data. However, new approaches allow us to quantify TE polymorphisms in population datasets and address fundamental questions about the evolution of these polymorphisms. Here, we discuss how insertional biases shape where, when, and how often TEs insert throughout the genome. Next, we examine mechanisms by which TEs can affect phenotype. Finally, we evaluate current evidence for selection on TE polymorphisms. All together, it is clear that TEs are important, but underappreciated, contributors to intraspecific phenotypic variation, and that understanding the dynamics governing TE polymorphism is crucial for evolutionary biologists interested in the maintenance of variation.
Collapse
Affiliation(s)
- Nathan S Catlin
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA; Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, 48824, USA.
| | - Emily B Josephs
- Department of Plant Biology, Michigan State University, East Lansing, MI, 48824, USA; Ecology, Evolution, and Behavior Program, Michigan State University, East Lansing, MI, 48824, USA
| |
Collapse
|
16
|
Zykova T, Maltseva M, Goncharov F, Boldyreva L, Pokholkova G, Kolesnikova T, Zhimulev I. The Organization of Pericentromeric Heterochromatin in Polytene Chromosome 3 of the Drosophilamelanogaster Line with the Rif11; SuURES Su(var)3-906 Mutations Suppressing Underreplication. Cells 2021; 10:2809. [PMID: 34831030 PMCID: PMC8616060 DOI: 10.3390/cells10112809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 10/11/2021] [Accepted: 10/14/2021] [Indexed: 11/17/2022] Open
Abstract
Although heterochromatin makes up 40% of the Drosophila melanogaster genome, its organization remains little explored, especially in polytene chromosomes, as it is virtually not represented in them due to underreplication. Two all-new approaches were used in this work: (i) with the use of a newly synthesized Drosophila line that carries three mutations, Rif11, SuURES and Su(var)3-906, suppressing the underreplication of heterochromatic regions, we obtained their fullest representation in polytene chromosomes and described their structure; (ii) 20 DNA fragments with known positions on the physical map as well as molecular genetic features of the genome (gene density, histone marks, heterochromatin proteins, origin recognition complex proteins, replication timing sites and satellite DNAs) were mapped in the newly polytenized heterochromatin using FISH and bioinformatics data. The borders of the heterochromatic regions and variations in their positions on arm 3L have been determined for the first time. The newly polytenized heterochromatic material exhibits two main types of morphology: a banding pattern (locations of genes and short satellites) and reticular chromatin (locations of large blocks of satellite DNA). The locations of the banding and reticular polytene heterochromatin was determined on the physical map.
Collapse
Affiliation(s)
- Tatyana Zykova
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Mariya Maltseva
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Fedor Goncharov
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Lidia Boldyreva
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Galina Pokholkova
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
| | - Tatyana Kolesnikova
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
- Laboratory of Structural, Functional and Comparative Genomics Novosibirsk State University, 630090 Novosibirsk, Russia
| | - Igor Zhimulev
- Laboratory of Molecular Cytogenetics, Institute of Molecular and Cellular Biology SB RAS, 630090 Novosibirsk, Russia; (T.Z.); (M.M.); (F.G.); (L.B.); (G.P.); (T.K.)
- Laboratory of Structural, Functional and Comparative Genomics Novosibirsk State University, 630090 Novosibirsk, Russia
| |
Collapse
|
17
|
Castanera R, Vendrell-Mir P, Bardil A, Carpentier MC, Panaud O, Casacuberta JM. Amplification dynamics of miniature inverted-repeat transposable elements and their impact on rice trait variability. THE PLANT JOURNAL : FOR CELL AND MOLECULAR BIOLOGY 2021; 107:118-135. [PMID: 33866641 DOI: 10.1111/tpj.15277] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Revised: 03/31/2021] [Accepted: 04/08/2021] [Indexed: 06/12/2023]
Abstract
Transposable elements (TEs) are a rich source of genetic variability. Among TEs, miniature inverted-repeat TEs (MITEs) are of particular interest as they are present in high copy numbers in plant genomes and are closely associated with genes. MITEs are deletion derivatives of class II transposons, and can be mobilized by the transposases encoded by the latter through a typical cut-and-paste mechanism. However, MITEs are typically present at much higher copy numbers than class II transposons. We present here an analysis of 103 109 transposon insertion polymorphisms (TIPs) in 738 Oryza sativa genomes representing the main rice population groups. We show that an important fraction of MITE insertions has been fixed in rice concomitantly with its domestication. However, another fraction of MITE insertions is present at low frequencies. We performed MITE TIP-genome-wide association studies (TIP-GWAS) to study the impact of these elements on agronomically important traits and found that these elements uncover more trait associations than single nucleotide polymorphisms (SNPs) on important phenotypes such as grain width. Finally, using SNP-GWAS and TIP-GWAS we provide evidence of the replicative amplification of MITEs.
Collapse
Affiliation(s)
- Raúl Castanera
- Centre for Research in Agricultural Genomics CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Bellaterra, Barcelona, 08193, Spain
| | - Pol Vendrell-Mir
- Centre for Research in Agricultural Genomics CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Bellaterra, Barcelona, 08193, Spain
| | - Amélie Bardil
- Centre for Research in Agricultural Genomics CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Bellaterra, Barcelona, 08193, Spain
| | - Marie-Christine Carpentier
- Laboratoire Génome et Développement des Plantes, UMR CNRS/UPVD 5096, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan Cedex, 66860, France
| | - Olivier Panaud
- Laboratoire Génome et Développement des Plantes, UMR CNRS/UPVD 5096, Université de Perpignan Via Domitia, 52 Avenue Paul Alduy, Perpignan Cedex, 66860, France
| | - Josep M Casacuberta
- Centre for Research in Agricultural Genomics CSIC-IRTA-UAB-UB, Campus UAB, Edifici CRAG, Bellaterra, Barcelona, 08193, Spain
| |
Collapse
|
18
|
Ghanim GE, Rio DC, Teixeira FK. Mechanism and regulation of P element transposition. Open Biol 2020; 10:200244. [PMID: 33352068 PMCID: PMC7776569 DOI: 10.1098/rsob.200244] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 11/26/2020] [Indexed: 12/05/2022] Open
Abstract
P elements were first discovered in the fruit fly Drosophila melanogaster as the causative agents of a syndrome of aberrant genetic traits called hybrid dysgenesis. This occurs when P element-carrying males mate with females that lack P elements and results in progeny displaying sterility, mutations and chromosomal rearrangements. Since then numerous genetic, developmental, biochemical and structural studies have culminated in a deep understanding of P element transposition: from the cellular regulation and repression of transposition to the mechanistic details of the transposase nucleoprotein complex. Recent studies have revealed how piwi-interacting small RNA pathways can act to control splicing of the P element pre-mRNA to modulate transposase production in the germline. A recent cryo-electron microscopy structure of the P element transpososome reveals an unusual DNA architecture at the transposon termini and shows that the bound GTP cofactor functions to position the transposon ends within the transposase active site. Genome sequencing efforts have shown that there are P element transposase-homologous genes (called THAP9) in other animal genomes, including humans. This review highlights recent and previous studies, which together have led to new insights, and surveys our current understanding of the biology, biochemistry, mechanism and regulation of P element transposition.
Collapse
Affiliation(s)
- George E. Ghanim
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
| | - Donald C. Rio
- Department of Molecular and Cell Biology, University of California, Berkeley, CA 94720, USA
- California Institute for Quantitative Biosciences, University of California, Berkeley, CA 94720, USA
| | | |
Collapse
|
19
|
Abstract
Transposable elements (TEs) are mobile DNA sequences that propagate within genomes. Through diverse invasion strategies, TEs have come to occupy a substantial fraction of nearly all eukaryotic genomes, and they represent a major source of genetic variation and novelty. Here we review the defining features of each major group of eukaryotic TEs and explore their evolutionary origins and relationships. We discuss how the unique biology of different TEs influences their propagation and distribution within and across genomes. Environmental and genetic factors acting at the level of the host species further modulate the activity, diversification, and fate of TEs, producing the dramatic variation in TE content observed across eukaryotes. We argue that cataloging TE diversity and dissecting the idiosyncratic behavior of individual elements are crucial to expanding our comprehension of their impact on the biology of genomes and the evolution of species.
Collapse
Affiliation(s)
- Jonathan N Wells
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850; ,
| | - Cédric Feschotte
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14850; ,
| |
Collapse
|
20
|
Identification of Genes Involved in the Differentiation of R7y and R7p Photoreceptor Cells in Drosophila. G3-GENES GENOMES GENETICS 2020; 10:3949-3958. [PMID: 32972998 PMCID: PMC7642934 DOI: 10.1534/g3.120.401370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The R7 and R8 photoreceptor cells of the Drosophila compound eye mediate color vision. Throughout the majority of the eye, these cells occur in two principal types of ommatidia. Approximately 35% of ommatidia are of the pale type and express Rh3 in R7 cells and Rh5 in R8 cells. The remaining 65% are of the yellow type and express Rh4 in R7 cells and Rh6 in R8 cells. The specification of an R8 cell in a pale or yellow ommatidium depends on the fate of the adjacent R7 cell. However, pale and yellow R7 cells are specified by a stochastic process that requires the genes spineless, tango and klumpfuss. To identify additional genes involved in this process we performed genetic screens using a collection of 480 P{EP} transposon insertion strains. We identified genes in gain of function and loss of function screens that significantly altered the percentage of Rh3 expressing R7 cells (Rh3%) from wild-type. 36 strains resulted in altered Rh3% in the gain of function screen where the P{EP} insertion strains were crossed to a sevEP-GAL4 driver line. 53 strains resulted in altered Rh3% in the heterozygous loss of function screen. 4 strains showed effects that differed between the two screens, suggesting that the effect found in the gain of function screen was either larger than, or potentially masked by, the P{EP} insertion alone. Analyses of homozygotes validated many of the candidates identified. These results suggest that R7 cell fate specification is sensitive to perturbations in mRNA transcription, splicing and localization, growth inhibition, post-translational protein modification, cleavage and secretion, hedgehog signaling, ubiquitin protease activity, GTPase activation, actin and cytoskeletal regulation, and Ser/Thr kinase activity, among other diverse signaling and cell biological processes.
Collapse
|
21
|
Zhang X, Zhao M, McCarty DR, Lisch D. Transposable elements employ distinct integration strategies with respect to transcriptional landscapes in eukaryotic genomes. Nucleic Acids Res 2020; 48:6685-6698. [PMID: 32442316 PMCID: PMC7337890 DOI: 10.1093/nar/gkaa370] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2019] [Revised: 04/24/2020] [Accepted: 04/29/2020] [Indexed: 12/27/2022] Open
Abstract
Transposable elements (TEs) are ubiquitous DNA segments capable of moving from one site to another within host genomes. The extant distributions of TEs in eukaryotic genomes have been shaped by both bona fide TE integration preferences in eukaryotic genomes and by selection following integration. Here, we compare TE target site distribution in host genomes using multiple de novo transposon insertion datasets in both plants and animals and compare them in the context of genome-wide transcriptional landscapes. We showcase two distinct types of transcription-associated TE targeting strategies that suggest a process of convergent evolution among eukaryotic TE families. The integration of two precision-targeting elements are specifically associated with initiation of RNA Polymerase II transcription of highly expressed genes, suggesting the existence of novel mechanisms of precision TE targeting in addition to passive targeting of open chromatin. We also highlight two features that can facilitate TE survival and rapid proliferation: tissue-specific transposition and minimization of negative impacts on nearby gene function due to precision targeting.
Collapse
Affiliation(s)
- Xinyan Zhang
- Shenzhen Branch, Guangdong Laboratory for Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen 518120, China
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
| | - Meixia Zhao
- Department of Biology, Miami University, Oxford, OH 45056, USA
| | - Donald R McCarty
- Horticultural Sciences Department, University of Florida, Gainesville, FL 32611, USA
| | - Damon Lisch
- Department of Botany and Plant Pathology, Purdue University, West Lafayette, IN 47907, USA
| |
Collapse
|
22
|
Kelleher ES, Barbash DA, Blumenstiel JP. Taming the Turmoil Within: New Insights on the Containment of Transposable Elements. Trends Genet 2020; 36:474-489. [PMID: 32473745 DOI: 10.1016/j.tig.2020.04.007] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2020] [Revised: 04/15/2020] [Accepted: 04/17/2020] [Indexed: 12/28/2022]
Abstract
Transposable elements (TEs) are mobile genetic parasites that can exponentially increase their genomic abundance through self-propagation. Classic theoretical papers highlighted the importance of two potentially escalating forces that oppose TE spread: regulated transposition and purifying selection. Here, we review new insights into mechanisms of TE regulation and purifying selection, which reveal the remarkable foresight of these theoretical models. We further highlight emergent connections between transcriptional control enacted by small RNAs and the contribution of TE insertions to structural mutation and host-gene regulation. Finally, we call for increased comparative analysis of TE dynamics and fitness effects, as well as host control mechanisms, to reveal how interconnected forces shape the differential prevalence and distribution of TEs across the tree of life.
Collapse
|
23
|
Epigenetic Requirements for Triggering Heterochromatinization and Piwi-Interacting RNA Production from Transgenes in the Drosophila Germline. Cells 2020; 9:cells9040922. [PMID: 32290057 PMCID: PMC7226800 DOI: 10.3390/cells9040922] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/05/2020] [Accepted: 04/07/2020] [Indexed: 12/26/2022] Open
Abstract
Transgenes containing a fragment of the I retrotransposon represent a powerful model of piRNA cluster de novo formation in the Drosophila germline. We revealed that the same transgenes located at different genomic loci form piRNA clusters with various capacity of small RNA production. Transgenic piRNA clusters are not established in piRNA pathway mutants. However, in the wild-type context, the endogenous ancestral I-related piRNAs heterochromatinize and convert the I-containing transgenes into piRNA-producing loci. Here, we address how the quantitative level of piRNAs influences the heterochromatinization and piRNA production. We show that a minimal amount of maternal piRNAs from ancestral I-elements is sufficient to form the transgenic piRNA clusters. Supplemental piRNAs stemming from active I-element copies do not stimulate additional chromatin changes or piRNA production from transgenes. Therefore, chromatin changes and piRNA production are initiated by a minimum threshold level of complementary piRNAs, suggesting a selective advantage of prompt cell response to the lowest level of piRNAs. It is noteworthy that the weak piRNA clusters do not transform into strong ones after being targeted by abundant I-specific piRNAs, indicating the importance of the genomic context for piRNA cluster establishment. Analysis of ovarian transcription profiles suggests that regions facilitating convergent transcription favor the formation of transgenic piRNA clusters.
Collapse
|
24
|
Zhang S, Pointer B, Kelleher ES. Rapid evolution of piRNA-mediated silencing of an invading transposable element was driven by abundant de novo mutations. Genome Res 2020; 30:566-575. [PMID: 32238416 PMCID: PMC7197473 DOI: 10.1101/gr.251546.119] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Accepted: 03/24/2020] [Indexed: 11/24/2022]
Abstract
The regulation of transposable element (TE) activity by small RNAs is a ubiquitous feature of germlines. However, despite the obvious benefits to the host in terms of ensuring the production of viable gametes and maintaining the integrity of the genomes they carry, it remains controversial whether TE regulation evolves adaptively. We examined the emergence and evolutionary dynamics of repressor alleles after P-elements invaded the Drosophila melanogaster genome in the mid-twentieth century. In many animals including Drosophila, repressor alleles are produced by transpositional insertions into piRNA clusters, genomic regions encoding the Piwi-interacting RNAs (piRNAs) that regulate TEs. We discovered that ∼94% of recently collected isofemale lines in the Drosophila melanogaster Genetic Reference Panel (DGRP) contain at least one P-element insertion in a piRNA cluster, indicating that repressor alleles are produced by de novo insertion at an exceptional rate. Furthermore, in our sample of approximately 200 genomes, we uncovered no fewer than 80 unique P-element insertion alleles in at least 15 different piRNA clusters. Finally, we observe no footprint of positive selection on P-element insertions in piRNA clusters, suggesting that the rapid evolution of piRNA-mediated repression in D. melanogaster was driven primarily by mutation. Our results reveal for the first time how the unique genetic architecture of piRNA production, in which numerous piRNA clusters can encode regulatory small RNAs upon transpositional insertion, facilitates the nonadaptive rapid evolution of repression.
Collapse
Affiliation(s)
- Shuo Zhang
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA
| | - Beverly Pointer
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA
| | - Erin S Kelleher
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204, USA
| |
Collapse
|
25
|
Luo S, Zhang H, Duan Y, Yao X, Clark AG, Lu J. The evolutionary arms race between transposable elements and piRNAs in Drosophila melanogaster. BMC Evol Biol 2020; 20:14. [PMID: 31992188 PMCID: PMC6988346 DOI: 10.1186/s12862-020-1580-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2019] [Accepted: 01/13/2020] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND The piwi-interacting RNAs (piRNAs) are small non-coding RNAs that specifically repress transposable elements (TEs) in the germline of Drosophila. Despite our expanding understanding of TE:piRNA interaction, whether there is an evolutionary arms race between TEs and piRNAs was unclear. RESULTS Here, we studied the population genomics of TEs and piRNAs in the worldwide strains of D. melanogaster. By conducting a correlation analysis between TE contents and the abundance of piRNAs from ovaries of representative strains of D. melanogaster, we find positive correlations between TEs and piRNAs in six TE families. Our simulations further highlight that TE activities and the strength of purifying selection against TEs are important factors shaping the interactions between TEs and piRNAs. Our studies also suggest that the de novo generation of piRNAs is an important mechanism to repress the newly invaded TEs. CONCLUSIONS Our results revealed the existence of an evolutionary arms race between the copy numbers of TEs and the abundance of antisense piRNAs at the population level. Although the interactions between TEs and piRNAs are complex and many factors should be considered to impact their interaction dynamics, our results suggest the emergence, repression specificity and strength of piRNAs on TEs should be considered in studying the landscapes of TE insertions in Drosophila. These results deepen our understanding of the interactions between piRNAs and TEs, and also provide novel insights into the nature of genomic conflicts of other forms.
Collapse
Affiliation(s)
- Shiqi Luo
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, College of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
- College of Plant Protection, Beijing Advanced Innovation Center for Food Nutrition and Human Health, China Agricultural University, Beijing, 100193, China
| | - Hong Zhang
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, College of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Yuange Duan
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, College of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
- Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, 100871, China
| | - Xinmin Yao
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, College of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China
| | - Andrew G Clark
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA.
| | - Jian Lu
- State Key Laboratory of Protein and Plant Gene Research, Center for Bioinformatics, College of Life Sciences and Peking-Tsinghua Center for Life Sciences, Peking University, Beijing, 100871, China.
| |
Collapse
|
26
|
Expression-Based Cell Lineage Analysis in Drosophila Through a Course-Based Research Experience for Early Undergraduates. G3-GENES GENOMES GENETICS 2019; 9:3791-3800. [PMID: 31690598 PMCID: PMC6829132 DOI: 10.1534/g3.119.400541] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
A variety of genetic techniques have been devised to determine cell lineage relationships during tissue development. Some of these systems monitor cell lineages spatially and/or temporally without regard to gene expression by the cells, whereas others correlate gene expression with the lineage under study. The GAL4 Technique for Real-time and Clonal Expression (G-TRACE) system allows for rapid, fluorescent protein-based visualization of both current and past GAL4 expression patterns and is therefore amenable to genome-wide expression-based lineage screens. Here we describe the results from such a screen, performed by undergraduate students of the University of California, Los Angeles (UCLA) Undergraduate Research Consortium for Functional Genomics (URCFG) and high school summer scholars as part of a discovery-based education program. The results of the screen, which reveal novel expression-based lineage patterns within the brain, the imaginal disc epithelia, and the hematopoietic lymph gland, have been compiled into the G-TRACE Expression Database (GED), an online resource for use by the Drosophila research community. The impact of this discovery-based research experience on student learning gains was assessed independently and shown to be greater than that of similar programs conducted elsewhere. Furthermore, students participating in the URCFG showed considerably higher STEM retention rates than UCLA STEM students that did not participate in the URCFG, as well as STEM students nationwide.
Collapse
|
27
|
Scott JG, Buchon N. Drosophila melanogaster as a powerful tool for studying insect toxicology. PESTICIDE BIOCHEMISTRY AND PHYSIOLOGY 2019; 161:95-103. [PMID: 31685202 DOI: 10.1016/j.pestbp.2019.09.006] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Revised: 09/17/2019] [Accepted: 09/18/2019] [Indexed: 06/10/2023]
Abstract
Insecticides are valuable and widely used tools for the control of pest insects. Despite the use of synthetic insecticides for >50 years, we continue to have a limited understanding of the genes that influence the key steps of the poisoning process. Major barriers for improving our understanding of insecticide toxicity have included a narrow range of tools and/or a large number of candidate genes that could be involved in the poisoning process. Herein, we discuss the numerous tools and resources available in Drosophila melanogaster that could be brought to bear to improve our understanding of the processes determining insecticide toxicity. These include unbiased approaches such as forward genetic screens, population genetic methods and candidate gene approaches. Examples are provided to showcase how D. melanogaster has been successfully used for insecticide toxicology studies in the past, and ideas for future studies using this valuable insect are discussed.
Collapse
Affiliation(s)
- Jeffrey G Scott
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA.
| | - Nicolas Buchon
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, NY, USA
| |
Collapse
|
28
|
Flasch DA, Macia Á, Sánchez L, Ljungman M, Heras SR, García-Pérez JL, Wilson TE, Moran JV. Genome-wide de novo L1 Retrotransposition Connects Endonuclease Activity with Replication. Cell 2019; 177:837-851.e28. [PMID: 30955886 DOI: 10.1016/j.cell.2019.02.050] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 01/10/2019] [Accepted: 02/25/2019] [Indexed: 12/18/2022]
Abstract
L1 retrotransposon-derived sequences comprise approximately 17% of the human genome. Darwinian selective pressures alter L1 genomic distributions during evolution, confounding the ability to determine initial L1 integration preferences. Here, we generated high-confidence datasets of greater than 88,000 engineered L1 insertions in human cell lines that act as proxies for cells that accommodate retrotransposition in vivo. Comparing these insertions to a null model, in which L1 endonuclease activity is the sole determinant dictating L1 integration preferences, demonstrated that L1 insertions are not significantly enriched in genes, transcribed regions, or open chromatin. By comparison, we provide compelling evidence that the L1 endonuclease disproportionately cleaves predominant lagging strand DNA replication templates, while lagging strand 3'-hydroxyl groups may prime endonuclease-independent L1 retrotransposition in a Fanconi anemia cell line. Thus, acquisition of an endonuclease domain, in conjunction with the ability to integrate into replicating DNA, allowed L1 to become an autonomous, interspersed retrotransposon.
Collapse
Affiliation(s)
- Diane A Flasch
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, 48109, USA.
| | - Ángela Macia
- Department of Genomic Medicine, GENYO: Centre for Genomics and Oncology (Pfizer-University of Granada and Andalusian Regional Government), PTS Granada, 18016, Spain
| | - Laura Sánchez
- Department of Genomic Medicine, GENYO: Centre for Genomics and Oncology (Pfizer-University of Granada and Andalusian Regional Government), PTS Granada, 18016, Spain
| | - Mats Ljungman
- Department of Radiation Oncology, University of Michigan Comprehensive Cancer Center, Translational Oncology Program and Center for RNA Biomedicine, University of Michigan, Ann Arbor, Michigan, 48109, USA; Department of Environmental Health Sciences, School of Public Health, University of Michigan, Ann Arbor, Michigan, 48109, USA
| | - Sara R Heras
- Department of Genomic Medicine, GENYO: Centre for Genomics and Oncology (Pfizer-University of Granada and Andalusian Regional Government), PTS Granada, 18016, Spain
| | - José L García-Pérez
- Department of Genomic Medicine, GENYO: Centre for Genomics and Oncology (Pfizer-University of Granada and Andalusian Regional Government), PTS Granada, 18016, Spain; Medical Research Council Human Genetics Unit, Institute of Genetics and Molecular Medicine (IGMM), University of Edinburgh, Western General Hospital, Edinburgh EH4 2XU, UK
| | - Thomas E Wilson
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, 48109, USA; Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan, 48109, USA.
| | - John V Moran
- Department of Human Genetics, University of Michigan Medical School, Ann Arbor, Michigan, 48109, USA; Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, Michigan, 48109, USA.
| |
Collapse
|
29
|
Kelleher ES, Azevedo RBR, Zheng Y. The Evolution of Small-RNA-Mediated Silencing of an Invading Transposable Element. Genome Biol Evol 2018; 10:3038-3057. [PMID: 30252073 PMCID: PMC6404463 DOI: 10.1093/gbe/evy218] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/24/2018] [Indexed: 12/11/2022] Open
Abstract
Transposable elements (TEs) are genomic parasites that impose fitness costs on their
hosts by producing deleterious mutations and disrupting gametogenesis. Host genomes avoid
these costs by regulating TE activity, particularly in germline cells where new insertions
are heritable and TEs are exceptionally active. However, the capacity of different
TE-associated fitness costs to select for repression in the host, and the role of
selection in the evolution of TE regulation more generally remain controversial. In this
study, we use forward, individual-based simulations to examine the evolution of
small-RNA-mediated TE regulation, a conserved mechanism for TE repression that is employed
by both prokaryotes and eukaryotes. To design and parameterize a biologically realistic
model, we drew on an extensive survey of empirical studies of the transposition and
regulation of P-element DNA transposons in Drosophila
melanogaster. We observed that even under conservative assumptions, where
small-RNA-mediated regulation reduces transposition only, repression evolves rapidly and
adaptively after the genome is invaded by a new TE in simulated populations. We further
show that the spread of repressor alleles through simulated populations is greatly
enhanced by two additional TE-imposed fitness costs: dysgenic sterility and ectopic
recombination. Finally, we demonstrate that the adaptive mutation rate to repression is a
critical parameter that influences both the evolutionary trajectory of host repression and
the associated proliferation of TEs after invasion in simulated populations. Our findings
suggest that adaptive evolution of TE regulation may be stronger and more prevalent than
previously appreciated, and provide a framework for interpreting empirical data.
Collapse
Affiliation(s)
- Erin S Kelleher
- Department of Biology and Biochemistry, University of Houston, Houston
| | | | - Yichen Zheng
- Department of Biology and Biochemistry, University of Houston, Houston.,Biodiversitt und Klima Forschungszentrum, Senckenberg Gesellschaft fr Naturforschung, Frankfurt am Main, Germany.,Institute of Genetics, University of Cologne, 50674 Cologne, NRW, Germany
| |
Collapse
|
30
|
Moon S, Cassani M, Lin YA, Wang L, Dou K, Zhang ZZ. A Robust Transposon-Endogenizing Response from Germline Stem Cells. Dev Cell 2018; 47:660-671.e3. [PMID: 30393075 DOI: 10.1016/j.devcel.2018.10.011] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2018] [Revised: 08/06/2018] [Accepted: 10/05/2018] [Indexed: 01/30/2023]
Abstract
The heavy occupancy of transposons in the genome implies that existing organisms have survived from multiple, independent rounds of transposon invasions. However, how and which host cell types survive the initial wave of transposon invasion remain unclear. We show that the germline stem cells can initiate a robust adaptive response that rapidly endogenizes invading P element transposons by activating the DNA damage checkpoint and piRNA production. We find that temperature modulates the P element activity in germline stem cells, establishing a powerful tool to trigger transposon hyper-activation. Facing vigorous invasion, Drosophila first shut down oogenesis and induce selective apoptosis. Interestingly, a robust adaptive response occurs in ovarian stem cells through activation of the DNA damage checkpoint. Within 4 days, the hosts amplify P element-silencing piRNAs, repair DNA damage, subdue the transposon, and reinitiate oogenesis. We propose that this robust adaptive response can bestow upon organisms the ability to survive recurrent transposon invasions throughout evolution.
Collapse
Affiliation(s)
- Sungjin Moon
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Madeline Cassani
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Yu An Lin
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Lu Wang
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Kun Dou
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA
| | - Zz Zhao Zhang
- Department of Embryology, Carnegie Institution for Science, Baltimore, MD 21218, USA.
| |
Collapse
|
31
|
Kofler R, Senti KA, Nolte V, Tobler R, Schlötterer C. Molecular dissection of a natural transposable element invasion. Genome Res 2018; 28:824-835. [PMID: 29712752 PMCID: PMC5991514 DOI: 10.1101/gr.228627.117] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Accepted: 04/10/2018] [Indexed: 02/07/2023]
Abstract
The first tracking of the dynamics of a natural invasion by a transposable element (TE) provides unprecedented details on the establishment of host defense mechanisms against TEs. We captured a D. simulans population at an early stage of a P-element invasion and studied the spread of the TE in replicated experimentally evolving populations kept under hot and cold conditions. We analyzed the factors controlling the invasion by NGS, RNA-FISH, and gonadal dysgenesis assays. Under hot conditions, the P-element spread rapidly for 20 generations, but no further spread was noted later on. This plateauing of the invasion was mediated by the rapid emergence of P-element-specific piRNAs. Under cold conditions, we observed a lower expression of the P-element and a slower emergence of the piRNA defense, resulting in a three times slower invasion that continued beyond 40 generations. We conclude that the environment is a major factor determining the evolution of TEs in their host.
Collapse
Affiliation(s)
- Robert Kofler
- Institut für Populationsgenetik, Vetmeduni Vienna, 1210 Vienna, Austria
| | | | - Viola Nolte
- Institut für Populationsgenetik, Vetmeduni Vienna, 1210 Vienna, Austria
| | - Ray Tobler
- Institut für Populationsgenetik, Vetmeduni Vienna, 1210 Vienna, Austria
| | | |
Collapse
|
32
|
Mielich K, Shtifman-Segal E, Golz JC, Zeng G, Wang Y, Berman J, Kunze R. Maize Transposable Elements Ac/ Ds as Insertion Mutagenesis Tools in Candida albicans. G3 (BETHESDA, MD.) 2018; 8:1139-1145. [PMID: 29378819 PMCID: PMC5873905 DOI: 10.1534/g3.117.300388] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 01/26/2018] [Indexed: 12/23/2022]
Abstract
In nonmodel systems, genetic research is often limited by the lack of techniques for the generation and identification of gene mutations. One approach to overcome this bottleneck is the application of transposons for gene tagging. We have established a two-element transposon tagging system, based on the transposable elements Activator (Ac)/Dissociation (Ds) from maize, for in vivo insertion mutagenesis in the fungal human pathogen Candida albicans A nonautonomous Ds transposon carrying a selectable marker was constructed into the ADE2 promoter on chromosome 3 and a codon usage-adapted Ac transposase gene was inserted into the neutral NEUT5L locus on chromosome 5. In C. albicans cells expressing the transposase, the Ds element efficiently excised and reintegrated elsewhere in the genome, which makes the Ac/Ds transposons promising tools for saturating insertion mutagenesis in clinical strains of C. albicans.
Collapse
Affiliation(s)
- Kevin Mielich
- Institute of Biology, Dahlem Centre of Plant Sciences, Free University pf Berlin, 14195, Germany
| | - Ella Shtifman-Segal
- Department of Molecular Microbiology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Julia C Golz
- Institute of Biology, Dahlem Centre of Plant Sciences, Free University pf Berlin, 14195, Germany
| | - Guisheng Zeng
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 138673, Singapore
| | - Yue Wang
- Institute of Molecular and Cell Biology, Agency for Science, Technology and Research, 138673, Singapore
| | - Judith Berman
- Department of Molecular Microbiology and Biotechnology, George Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Reinhard Kunze
- Institute of Biology, Dahlem Centre of Plant Sciences, Free University pf Berlin, 14195, Germany
| |
Collapse
|
33
|
McGurk MP, Barbash DA. Double insertion of transposable elements provides a substrate for the evolution of satellite DNA. Genome Res 2018; 28:714-725. [PMID: 29588362 PMCID: PMC5932611 DOI: 10.1101/gr.231472.117] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2017] [Accepted: 03/22/2018] [Indexed: 02/06/2023]
Abstract
Eukaryotic genomes are replete with repeated sequences in the form of transposable elements (TEs) dispersed across the genome or as satellite arrays, large stretches of tandemly repeated sequences. Many satellites clearly originated as TEs, but it is unclear how mobile genetic parasites can transform into megabase-sized tandem arrays. Comprehensive population genomic sampling is needed to determine the frequency and generative mechanisms of tandem TEs, at all stages from their initial formation to their subsequent expansion and maintenance as satellites. The best available population resources, short-read DNA sequences, are often considered to be of limited utility for analyzing repetitive DNA due to the challenge of mapping individual repeats to unique genomic locations. Here we develop a new pipeline called ConTExt that demonstrates that paired-end Illumina data can be successfully leveraged to identify a wide range of structural variation within repetitive sequence, including tandem elements. By analyzing 85 genomes from five populations of Drosophila melanogaster, we discover that TEs commonly form tandem dimers. Our results further suggest that insertion site preference is the major mechanism by which dimers arise and that, consequently, dimers form rapidly during periods of active transposition. This abundance of TE dimers has the potential to provide source material for future expansion into satellite arrays, and we discover one such copy number expansion of the DNA transposon hobo to approximately 16 tandem copies in a single line. The very process that defines TEs—transposition—thus regularly generates sequences from which new satellites can arise.
Collapse
Affiliation(s)
- Michael P McGurk
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| | - Daniel A Barbash
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, USA
| |
Collapse
|
34
|
Lee PT, Zirin J, Kanca O, Lin WW, Schulze KL, Li-Kroeger D, Tao R, Devereaux C, Hu Y, Chung V, Fang Y, He Y, Pan H, Ge M, Zuo Z, Housden BE, Mohr SE, Yamamoto S, Levis RW, Spradling AC, Perrimon N, Bellen HJ. A gene-specific T2A-GAL4 library for Drosophila. eLife 2018; 7:35574. [PMID: 29565247 PMCID: PMC5898912 DOI: 10.7554/elife.35574] [Citation(s) in RCA: 158] [Impact Index Per Article: 26.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Accepted: 03/16/2018] [Indexed: 12/18/2022] Open
Abstract
We generated a library of ~1000 Drosophila stocks in which we inserted a construct in the intron of genes allowing expression of GAL4 under control of endogenous promoters while arresting transcription with a polyadenylation signal 3’ of the GAL4. This allows numerous applications. First, ~90% of insertions in essential genes cause a severe loss-of-function phenotype, an effective way to mutagenize genes. Interestingly, 12/14 chromosomes engineered through CRISPR do not carry second-site lethal mutations. Second, 26/36 (70%) of lethal insertions tested are rescued with a single UAS-cDNA construct. Third, loss-of-function phenotypes associated with many GAL4 insertions can be reverted by excision with UAS-flippase. Fourth, GAL4 driven UAS-GFP/RFP reports tissue and cell-type specificity of gene expression with high sensitivity. We report the expression of hundreds of genes not previously reported. Finally, inserted cassettes can be replaced with GFP or any DNA. These stocks comprise a powerful resource for assessing gene function. Determining what role newly discovered genes play in the body is an important part of genetics. This task requires a lot of extra information about each gene, such as the specific cells where the gene is active, or what happens when the gene is deleted. To answer these questions, researchers need tools and methods to manipulate genes within a living organism. The fruit fly Drosophila is useful for such experiments because a toolbox of genetic techniques is already available. Gene editing in fruit flies allows small pieces of genetic information to be removed from or added to anywhere in the animal’s DNA. Another tool, known as GAL4-UAS, is a two-part system used to study gene activity. The GAL4 component is a protein that switches on genes. GAL4 alone does very little in Drosophila cells because it only recognizes a DNA sequence called UAS. However, if a GAL4-producing cell is also engineered to contain a UAS-controlled gene, GAL4 will switch the gene on. Lee et al. used gene editing to insert a small piece of DNA, containing the GAL4 sequence followed by a ‘stop’ signal, into many different fly genes. The insertion made the cells where each gene was normally active produce GAL4, but – thanks to the stop signal – rendered the rest of the original gene non-functional. This effectively deleted the proteins encoded by each gene, giving information about the biological processes they normally control. Lee et al. went on to use their insertion approach to make a Drosophila genetic library. This is a collection of around 1,000 different strains of fly, each carrying the GAL4/stop combination in a single gene. The library allows any gene in the collection to be studied in detail simply by combining the GAL4 with different UAS-controlled genetic tools. For example, introducing a UAS-controlled marker would pinpoint where in the body the original gene was active. Alternatively, adding UAS-controlled human versions of the gene would create humanized flies, which are a valuable tool to study potential disease-causing genes in humans. This Drosophila library is a resource that contributes new experimental tools to fly genetics. Insights gained from flies can also be applied to more complex animals like humans, especially since around 65% of genes are similar across humans and Drosophila. As such, Lee et al. hope that this resource will help other researchers shed new light on the role of many different genes in health and disease.
Collapse
Affiliation(s)
- Pei-Tseng Lee
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Jonathan Zirin
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Wen-Wen Lin
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Karen L Schulze
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - David Li-Kroeger
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Rong Tao
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Colby Devereaux
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Yanhui Hu
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Verena Chung
- Department of Genetics, Harvard Medical School, Boston, United States
| | - Ying Fang
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Yuchun He
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Hongling Pan
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States
| | - Ming Ge
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States
| | - Zhongyuan Zuo
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States
| | | | - Stephanie E Mohr
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States
| | - Shinya Yamamoto
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
| | - Robert W Levis
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Allan C Spradling
- Department of Embryology, Howard Hughes Medical Institute, Carnegie Institution for Science, Baltimore, United States
| | - Norbert Perrimon
- Department of Genetics, Harvard Medical School, Boston, United States.,Howard Hughes Medical Institute, Harvard Medical School, Boston, United States
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, United States.,Howard Hughes Medical Institute, Baylor College of Medicine, Houston, United States.,Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, United States.,Program in Developmental Biology, Baylor College of Medicine, Houston, United States.,Department of Neuroscience, Baylor College of Medicine, Houston, United States
| |
Collapse
|
35
|
Korona D, Koestler SA, Russell S. Engineering the Drosophila Genome for Developmental Biology. J Dev Biol 2017; 5:jdb5040016. [PMID: 29615571 PMCID: PMC5831791 DOI: 10.3390/jdb5040016] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2017] [Revised: 12/07/2017] [Accepted: 12/08/2017] [Indexed: 02/07/2023] Open
Abstract
The recent development of transposon and CRISPR-Cas9-based tools for manipulating the fly genome in vivo promises tremendous progress in our ability to study developmental processes. Tools for introducing tags into genes at their endogenous genomic loci facilitate imaging or biochemistry approaches at the cellular or subcellular levels. Similarly, the ability to make specific alterations to the genome sequence allows much more precise genetic control to address questions of gene function.
Collapse
Affiliation(s)
- Dagmara Korona
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK.
| | - Stefan A Koestler
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK.
| | - Steven Russell
- Department of Genetics, University of Cambridge, Downing Street, Cambridge CB2 3EH, UK.
| |
Collapse
|
36
|
Kanca O, Bellen HJ, Schnorrer F. Gene Tagging Strategies To Assess Protein Expression, Localization, and Function in Drosophila. Genetics 2017; 207:389-412. [PMID: 28978772 PMCID: PMC5629313 DOI: 10.1534/genetics.117.199968] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 06/13/2017] [Indexed: 01/15/2023] Open
Abstract
Analysis of gene function in complex organisms relies extensively on tools to detect the cellular and subcellular localization of gene products, especially proteins. Typically, immunostaining with antibodies provides these data. However, due to cost, time, and labor limitations, generating specific antibodies against all proteins of a complex organism is not feasible. Furthermore, antibodies do not enable live imaging studies of protein dynamics. Hence, tagging genes with standardized immunoepitopes or fluorescent tags that permit live imaging has become popular. Importantly, tagging genes present in large genomic clones or at their endogenous locus often reports proper expression, subcellular localization, and dynamics of the encoded protein. Moreover, these tagging approaches allow the generation of elegant protein removal strategies, standardization of visualization protocols, and permit protein interaction studies using mass spectrometry. Here, we summarize available genomic resources and techniques to tag genes and discuss relevant applications that are rarely, if at all, possible with antibodies.
Collapse
Affiliation(s)
- Oguz Kanca
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
| | - Hugo J Bellen
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
- Jan and Dan Duncan Neurological Research Institute, Texas Children's Hospital, Houston, Texas 77030
- Program in Developmental Biology, Baylor College of Medicine, Houston, Texas 77030
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas 77030
- Howard Hughes Medical Institute, Houston, Texas 77030
| | - Frank Schnorrer
- Developmental Biology Institute of Marseille (IBDM), UMR 7288, CNRS, Aix-Marseille Université, 13288, France
| |
Collapse
|
37
|
Anzai IA, Shaket L, Adesina O, Baym M, Barstow B. Rapid curation of gene disruption collections using Knockout Sudoku. Nat Protoc 2017; 12:2110-2137. [DOI: 10.1038/nprot.2017.073] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
|
38
|
Ren X, Holsteens K, Li H, Sun J, Zhang Y, Liu LP, Liu Q, Ni JQ. Genome editing in Drosophila melanogaster: from basic genome engineering to the multipurpose CRISPR-Cas9 system. SCIENCE CHINA-LIFE SCIENCES 2017; 60:476-489. [PMID: 28527116 DOI: 10.1007/s11427-017-9029-9] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Accepted: 03/05/2017] [Indexed: 12/16/2022]
Abstract
Nowadays, genome editing tools are indispensable for studying gene function in order to increase our knowledge of biochemical processes and disease mechanisms. The extensive availability of mutagenesis and transgenesis tools make Drosophila melanogaster an excellent model organism for geneticists. Early mutagenesis tools relied on chemical or physical methods, ethyl methane sulfonate (EMS) and X-rays respectively, to randomly alter DNA at a nucleotide or chromosomal level. Since the discovery of transposable elements and the availability of the complete fly genome, specific genome editing tools, such as P-elements, zinc-finger nucleases (ZFNs) and transcription activator-like effector nucleases (TALENs), have undergone rapid development. Currently, one of the leading and most effective contemporary tools is the CRISPR-cas9 system made popular because of its low cost, effectiveness, specificity and simplicity of use. This review briefly addresses the most commonly used mutagenesis and transgenesis tools in Drosophila, followed by an in-depth review of the multipurpose CRISPR-Cas9 system and its current applications.
Collapse
Affiliation(s)
- Xingjie Ren
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Kristof Holsteens
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Haiyi Li
- French International School of Hong Kong, Hong Kong SAR, 999000, China
| | - Jin Sun
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Yifan Zhang
- Department of Biology, University of California, San Diego, 92093, USA
| | - Lu-Ping Liu
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China
| | - Qingfei Liu
- School of Pharmaceutical Sciences, Tsinghua University, Beijing, 100084, China.
| | - Jian-Quan Ni
- Gene Regulatory Lab, School of Medicine, Tsinghua University, Beijing, 100084, China.
| |
Collapse
|
39
|
Adrion JR, Song MJ, Schrider DR, Hahn MW, Schaack S. Genome-Wide Estimates of Transposable Element Insertion and Deletion Rates in Drosophila Melanogaster. Genome Biol Evol 2017; 9:1329-1340. [PMID: 28338986 PMCID: PMC5447328 DOI: 10.1093/gbe/evx050] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/08/2017] [Indexed: 02/06/2023] Open
Abstract
Knowing the rate at which transposable elements (TEs) insert and delete is critical for understanding their role in genome evolution. We estimated spontaneous rates of insertion and deletion for all known, active TE superfamilies present in a set of Drosophila melanogaster mutation-accumulation (MA) lines using whole genome sequence data. Our results demonstrate that TE insertions far outpace TE deletions in D. melanogaster. We found a significant effect of background genotype on TE activity, with higher rates of insertions in one MA line. We also found significant rate heterogeneity between the chromosomes, with both insertion and deletion rates elevated on the X relative to the autosomes. Further, we identified significant associations between TE activity and chromatin state, and tested for associations between TE activity and other features of the local genomic environment such as TE content, exon content, GC content, and recombination rate. Our results provide the most detailed assessment of TE mobility in any organism to date, and provide a useful benchmark for both addressing theoretical predictions of TE dynamics and for exploring large-scale patterns of TE movement in D. melanogaster and other species.
Collapse
Affiliation(s)
| | - Michael J. Song
- Department of Integrative Biology, University of California, Berkeley, CA
| | - Daniel R. Schrider
- Department of Genetics, Rutgers, The State University of New Jersey, Piscataway, NJ
| | - Matthew W. Hahn
- Department of Biology, Indiana University, Bloomington, IN
- School of Informatics and Computing, Indiana University, Bloomington, IN
| | | |
Collapse
|
40
|
McCullers TJ, Steiniger M. Transposable elements in Drosophila. Mob Genet Elements 2017; 7:1-18. [PMID: 28580197 PMCID: PMC5443660 DOI: 10.1080/2159256x.2017.1318201] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Revised: 04/07/2017] [Accepted: 04/07/2017] [Indexed: 11/09/2022] Open
Abstract
Transposable elements (TEs) are mobile genetic elements that can mobilize within host genomes. As TEs comprise more than 40% of the human genome and are linked to numerous diseases, understanding their mechanisms of mobilization and regulation is important. Drosophila melanogaster is an ideal model organism for the study of eukaryotic TEs as its genome contains a diverse array of active TEs. TEs universally impact host genome size via transposition and deletion events, but may also adopt unique functional roles in host organisms. There are 2 main classes of TEs: DNA transposons and retrotransposons. These classes are further divided into subgroups of TEs with unique structural and functional characteristics, demonstrating the significant variability among these elements. Despite this variability, D. melanogaster and other eukaryotic organisms utilize conserved mechanisms to regulate TEs. This review focuses on the transposition mechanisms and regulatory pathways of TEs, and their functional roles in D. melanogaster.
Collapse
Affiliation(s)
| | - Mindy Steiniger
- Department of Biology, University of Missouri, St. Louis, MO, USA
| |
Collapse
|
41
|
Gramates LS, Marygold SJ, Santos GD, Urbano JM, Antonazzo G, Matthews BB, Rey AJ, Tabone CJ, Crosby MA, Emmert DB, Falls K, Goodman JL, Hu Y, Ponting L, Schroeder AJ, Strelets VB, Thurmond J, Zhou P. FlyBase at 25: looking to the future. Nucleic Acids Res 2017; 45:D663-D671. [PMID: 27799470 PMCID: PMC5210523 DOI: 10.1093/nar/gkw1016] [Citation(s) in RCA: 404] [Impact Index Per Article: 57.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Revised: 10/14/2016] [Accepted: 10/18/2016] [Indexed: 01/12/2023] Open
Abstract
Since 1992, FlyBase (flybase.org) has been an essential online resource for the Drosophila research community. Concentrating on the most extensively studied species, Drosophila melanogaster, FlyBase includes information on genes (molecular and genetic), transgenic constructs, phenotypes, genetic and physical interactions, and reagents such as stocks and cDNAs. Access to data is provided through a number of tools, reports, and bulk-data downloads. Looking to the future, FlyBase is expanding its focus to serve a broader scientific community. In this update, we describe new features, datasets, reagent collections, and data presentations that address this goal, including enhanced orthology data, Human Disease Model Reports, protein domain search and visualization, concise gene summaries, a portal for external resources, video tutorials and the FlyBase Community Advisory Group.
Collapse
Affiliation(s)
- L Sian Gramates
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Steven J Marygold
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Gilberto Dos Santos
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Jose-Maria Urbano
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Giulia Antonazzo
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Beverley B Matthews
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Alix J Rey
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Christopher J Tabone
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Madeline A Crosby
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - David B Emmert
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Kathleen Falls
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Joshua L Goodman
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Yanhui Hu
- Department of Genetics, Harvard Medical School, 77 Avenue Louis Pasteur, Boston, MA 02115, USA
| | - Laura Ponting
- Department of Physiology, Development and Neuroscience, University of Cambridge, Downing Street, Cambridge CB2 3DY, UK
| | - Andrew J Schroeder
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| | - Victor B Strelets
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Jim Thurmond
- Department of Biology, Indiana University, Bloomington, IN 47405, USA
| | - Pinglei Zhou
- The Biological Laboratories, Harvard University, 16 Divinity Avenue, Cambridge, MA 02138, USA
| |
Collapse
|
42
|
Rapid construction of a whole-genome transposon insertion collection for Shewanella oneidensis by Knockout Sudoku. Nat Commun 2016; 7:13270. [PMID: 27830751 PMCID: PMC5109470 DOI: 10.1038/ncomms13270] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 09/14/2016] [Indexed: 02/07/2023] Open
Abstract
Whole-genome knockout collections are invaluable for connecting gene sequence to function, yet traditionally, their construction has required an extraordinary technical effort. Here we report a method for the construction and purification of a curated whole-genome collection of single-gene transposon disruption mutants termed Knockout Sudoku. Using simple combinatorial pooling, a highly oversampled collection of mutants is condensed into a next-generation sequencing library in a single day, a 30- to 100-fold improvement over prior methods. The identities of the mutants in the collection are then solved by a probabilistic algorithm that uses internal self-consistency within the sequencing data set, followed by rapid algorithmically guided condensation to a minimal representative set of mutants, validation, and curation. Starting from a progenitor collection of 39,918 mutants, we compile a quality-controlled knockout collection of the electroactive microbe Shewanella oneidensis MR-1 containing representatives for 3,667 genes that is functionally validated by high-throughput kinetic measurements of quinone reduction. Knockout collections provide a valuable tool to explore gene function, yet are expensive and technically challenging to produce at a genome-wide scale. Here Baym et al. devise a cost-effective transposon-based method to quickly develop a knockout collection for the electroactive microbe Shewanella oneidensis.
Collapse
|
43
|
Sjulson L, Cassataro D, DasGupta S, Miesenböck G. Cell-Specific Targeting of Genetically Encoded Tools for Neuroscience. Annu Rev Genet 2016; 50:571-594. [PMID: 27732792 DOI: 10.1146/annurev-genet-120215-035011] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Genetically encoded tools for visualizing and manipulating neurons in vivo have led to significant advances in neuroscience, in large part because of the ability to target expression to specific cell populations of interest. Current methods enable targeting based on marker gene expression, development, anatomical projection pattern, synaptic connectivity, and recent activity as well as combinations of these factors. Here, we review these methods, focusing on issues of practical implementation as well as areas for future improvement.
Collapse
Affiliation(s)
- Lucas Sjulson
- Department of Psychiatry, New York University School of Medicine, New York, NY 10016; .,Department of Neuroscience and Physiology, Smilow Neuroscience Program, and New York University Neuroscience Institute, New York, NY 10016
| | - Daniela Cassataro
- Department of Neuroscience and Physiology, Smilow Neuroscience Program, and New York University Neuroscience Institute, New York, NY 10016
| | - Shamik DasGupta
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford, OX1 3SR, United Kingdom; .,Present address: Tata Institute of Fundamental Research, Mumbai, 400005, India
| | - Gero Miesenböck
- Centre for Neural Circuits and Behaviour, University of Oxford, Oxford, OX1 3SR, United Kingdom;
| |
Collapse
|
44
|
Huang Y, Liu Z, Rong YS. Genome Editing: From Drosophila to Non-Model Insects and Beyond. J Genet Genomics 2016; 43:263-72. [PMID: 27216295 DOI: 10.1016/j.jgg.2016.04.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2016] [Revised: 04/06/2016] [Accepted: 04/20/2016] [Indexed: 12/21/2022]
Abstract
Insect is the largest group of animals on land. Many insect species inflict economical and health losses to humans. Yet many more benefit us by helping to maintain balances in our ecosystem. The benefits that insects offer remain largely untapped, justifying our continuing efforts to develop tools to better understand their biology and to better manage their activities. Here we focus on reviewing the progresses made in the development of genome engineering tools for model insects. Instead of detailed descriptions of the molecular mechanisms underlying each technical advance, we focus our discussion on the logistics for implementing similar tools in non-model insects. Since none of the tools were developed specific for insects, similar approaches can be applied to other non-model organisms.
Collapse
Affiliation(s)
- Yueping Huang
- Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Zhiping Liu
- Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China
| | - Yikang S Rong
- Institute of Entomology, School of Life Sciences, Sun Yat-sen University, Guangzhou 510006, China.
| |
Collapse
|
45
|
Abstract
This chapter presents an analysis of the organization and distribution of the IS200/IS605 family of insertion sequences (IS). Members of this family are widespread in both bacteria and archaea. They are unusual because they use obligatory single-strand DNA intermediates, which distinguishes them from classical IS. We summarize studies of the experimental model systems IS608 (from Helicobacter pylori) and ISDra2 (from Deinococcus radiodurans) and present biochemical, genetic, and structural data that describe their transposition pathway and the way in which their transposase (an HuH rather than a DDE enzyme) catalyzes this process. The transposition of IS200/IS605 family members can be described as a "Peel-and-Paste" mechanism. We also address the probable domestication of IS200/IS605 family transposases as enzymes involved in multiplication of repeated extragenic palindromes and as potential homing endonucleases in intron-IS chimeras.
Collapse
|
46
|
Harrington AW, Steiniger M. Bioinformatic analyses of sense and antisense expression from terminal inverted repeat transposons in Drosophila somatic cells. Fly (Austin) 2016; 10:1-10. [PMID: 26986720 DOI: 10.1080/19336934.2016.1165372] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
Abstract
Understanding regulation of transposon movement in somatic cells is important as mobile elements can cause detrimental genomic rearrangements. Generally, transposons move via one of 2 mechanisms; retrotransposons utilize an RNA intermediate, therefore copying themselves and amplifying throughout the genome, while terminal inverted repeat transposons (TIR Tns) excise DNA sequences from the genome and integrate into a new location. Our recently published work indicates that retrotransposons in Drosophila tissue culture cells are actively transcribed in the antisense direction. Our data support a model in which convergent transcription of retrotransposons from intra element transcription start sites results in complementary RNAs that hybridize to form substrates for Dicer-2, the endogenous small interfering (esi)RNA generating enzyme. Here, we extend our previous analysis to TIR Tns. In contrast to retrotransposons, our data show that antisense TIR Tn RNAs result from transcription of intronic TIR Tns oriented antisense to their host genes. Also, disproportionately less esiRNAs are generated from TIR transcripts than from retrotransposons and transcription of very few individual TIR Tns could be confirmed. Collectively, these data support a model in which TIR Tns are regulated at the level of Transposase production while retrotransposons are regulated with esiRNA post-transcriptional mechanisms in Drosophila somatic cells.
Collapse
Affiliation(s)
| | - Mindy Steiniger
- a Department of Biology , University of Missouri , St. Louis , MO , USA
| |
Collapse
|
47
|
Filée J, Rouault JD, Harry M, Hua-Van A. Mariner transposons are sailing in the genome of the blood-sucking bug Rhodnius prolixus. BMC Genomics 2015; 16:1061. [PMID: 26666222 PMCID: PMC4678618 DOI: 10.1186/s12864-015-2060-9] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 10/10/2015] [Indexed: 11/30/2022] Open
Abstract
Background The Triatomine bug Rhodnius prolixus is a vector of Trypanosoma cruzi, which causes the Chagas disease in Latin America. R. prolixus can also transfer transposable elements horizontally across a wide range of species. We have taken advantage of the availability of the 700 Mbp complete genome sequence of R. prolixus to study the dynamics of invasion and persistence of transposable elements in this species. Results Using both library-based and de novo methods of transposon detection, we found less than 6 % of transposable elements in the R. prolixus genome, a relatively low percentage compared to other insect genomes with a similar genome size. DNA transposons are surprisingly abundant and elements belonging to the mariner family are by far the most preponderant components of the mobile part of this genome with 11,015 mariner transposons that could be clustered in 89 groups (75 % of the mobilome). Our analysis allowed the detection of a new mariner clade in the R. prolixus genome, that we called nosferatis. We demonstrated that a large diversity of mariner elements invaded the genome and expanded successfully over time via three main processes. (i) several families experienced recent and massive expansion, for example an explosive burst of a single mariner family led to the generation of more than 8000 copies. These recent expansion events explain the unusual prevalence of mariner transposons in the R. prolixus genome. Other families expanded via older bursts of transposition demonstrating the long lasting permissibility of mariner transposons in the R. prolixus genome. (ii) Many non-autonomous families generated by internal deletions were also identified. Interestingly, two non autonomous families were generated by atypical recombinations (5' part replacement with 3' part). (iii) at least 10 cases of horizontal transfers were found, supporting the idea that host/vector relationships played a pivotal role in the transmission and subsequent persistence of transposable elements in this genome. Conclusion These data provide a new insight into the evolution of transposons in the genomes of hematophagous insects and bring additional evidences that lateral exchanges of mobile genetics elements occur frequently in the R. prolixus genome. Electronic supplementary material The online version of this article (doi:10.1186/s12864-015-2060-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Jonathan Filée
- Laboratoire Evolution, Génome, Comportement, Ecologie UMR9191 CNRS, IRD Université Paris-Sud, Gif-sur-Yvette, France.
| | - Jacques-Deric Rouault
- Laboratoire Evolution, Génome, Comportement, Ecologie UMR9191 CNRS, IRD Université Paris-Sud, Gif-sur-Yvette, France
| | - Myriam Harry
- Laboratoire Evolution, Génome, Comportement, Ecologie UMR9191 CNRS, IRD Université Paris-Sud, Gif-sur-Yvette, France.,UFR de Sciences, Université Paris Sud, Orsay, France
| | - Aurélie Hua-Van
- Laboratoire Evolution, Génome, Comportement, Ecologie UMR9191 CNRS, IRD Université Paris-Sud, Gif-sur-Yvette, France.,UFR de Sciences, Université Paris Sud, Orsay, France
| |
Collapse
|
48
|
Molla-Herman A, Vallés AM, Ganem-Elbaz C, Antoniewski C, Huynh JR. tRNA processing defects induce replication stress and Chk2-dependent disruption of piRNA transcription. EMBO J 2015; 34:3009-27. [PMID: 26471728 PMCID: PMC4687792 DOI: 10.15252/embj.201591006] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 09/01/2015] [Accepted: 09/04/2015] [Indexed: 02/01/2023] Open
Abstract
RNase P is a conserved endonuclease that processes the 5' trailer of tRNA precursors. We have isolated mutations in Rpp30, a subunit of RNase P, and find that these induce complete sterility in Drosophila females. Here, we show that sterility is not due to a shortage of mature tRNAs, but that atrophied ovaries result from the activation of several DNA damage checkpoint proteins, including p53, Claspin, and Chk2. Indeed, we find that tRNA processing defects lead to increased replication stress and de-repression of transposable elements in mutant ovaries. We also report that transcription of major piRNA sources collapse in mutant germ cells and that this correlates with a decrease in heterochromatic H3K9me3 marks on the corresponding piRNA-producing loci. Our data thus link tRNA processing, DNA replication, and genome defense by small RNAs. This unexpected connection reveals constraints that could shape genome organization during evolution.
Collapse
Affiliation(s)
- Anahi Molla-Herman
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| | - Ana Maria Vallés
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| | - Carine Ganem-Elbaz
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| | - Christophe Antoniewski
- GED, UPMC, CNRS UMR 7622, IBPS, Developmental Biology Laboratory (IBPS-LBD), Paris, France
| | - Jean-René Huynh
- Department of Genetics and Developmental Biology, Institut Curie, Paris, France CNRS UMR3215, Inserm U934, Paris, France
| |
Collapse
|
49
|
Tools for Targeted Genome Engineering of Established Drosophila Cell Lines. Genetics 2015; 201:1307-18. [PMID: 26450921 PMCID: PMC4676523 DOI: 10.1534/genetics.115.181610] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 10/04/2015] [Indexed: 11/18/2022] Open
Abstract
We describe an adaptation of φC31 integrase-mediated targeted cassette exchange for use in Drosophila cell lines. Single copies of an attP-bounded docking platform carrying a GFP-expression marker, with or without insulator elements flanking the attP sites, were inserted by P-element transformation into the Kc167 and Sg4 cell lines; each of the resulting docking-site lines carries a single mapped copy of one of the docking platforms. Vectors for targeted substitution contain a cloning cassette flanked by attB sites. Targeted substitution occurs by integrase-mediated substitution between the attP sites (integrated) and the attB sites (vector). We describe procedures for isolating cells carrying the substitutions and for eliminating the products of secondary off-target events. We demonstrate the technology by integrating a cassette containing a Cu(2+)-inducible mCherry marker, and we report the expression properties of those lines. When compared with clonal lines made by traditional transformation methods, which lead to the illegitimate insertion of tandem arrays, targeted insertion lines give more uniform expression, lower basal expression, and higher induction ratios. Targeted substitution, though intricate, affords results that should greatly improve comparative expression assays-a major emphasis of cell-based studies.
Collapse
|
50
|
Brunet TDP, Doolittle WF. Multilevel Selection Theory and the Evolutionary Functions of Transposable Elements. Genome Biol Evol 2015; 7:2445-57. [PMID: 26253318 PMCID: PMC4558868 DOI: 10.1093/gbe/evv152] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
One of several issues at play in the renewed debate over “junk DNA” is the organizational level at which genomic features might be seen as selected, and thus to exhibit function, as etiologically defined. The intuition frequently expressed by molecular geneticists that junk DNA is functional because it serves to “speed evolution” or as an “evolutionary repository” could be recast as a claim about selection between species (or clades) rather than within them, but this is not often done. Here, we review general arguments for the importance of selection at levels above that of organisms in evolution, and develop them further for a common genomic feature: the carriage of transposable elements (TEs). In many species, not least our own, TEs comprise a large fraction of all nuclear DNA, and whether they individually or collectively contribute to fitness—or are instead junk— is a subject of ongoing contestation. Even if TEs generally owe their origin to selfish selection at the lowest level (that of genomes), their prevalence in extant organisms and the prevalence of extant organisms bearing them must also respond to selection within species (on organismal fitness) and between species (on rates of speciation and extinction). At an even higher level, the persistence of clades may be affected (positively or negatively) by TE carriage. If indeed TEs speed evolution, it is at these higher levels of selection that such a function might best be attributed to them as a class.
Collapse
Affiliation(s)
- Tyler D P Brunet
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| | - W Ford Doolittle
- Department of Biochemistry and Molecular Biology, Dalhousie University, Halifax, Nova Scotia, Canada
| |
Collapse
|