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Fabry MH, Falconio FA, Joud F, Lythgoe EK, Czech B, Hannon GJ. Maternally inherited piRNAs direct transient heterochromatin formation at active transposons during early Drosophila embryogenesis. eLife 2021; 10:e68573. [PMID: 34236313 PMCID: PMC8352587 DOI: 10.7554/elife.68573] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Accepted: 07/07/2021] [Indexed: 12/12/2022] Open
Abstract
The PIWI-interacting RNA (piRNA) pathway controls transposon expression in animal germ cells, thereby ensuring genome stability over generations. In Drosophila, piRNAs are intergenerationally inherited through the maternal lineage, and this has demonstrated importance in the specification of piRNA source loci and in silencing of I- and P-elements in the germ cells of daughters. Maternally inherited Piwi protein enters somatic nuclei in early embryos prior to zygotic genome activation and persists therein for roughly half of the time required to complete embryonic development. To investigate the role of the piRNA pathway in the embryonic soma, we created a conditionally unstable Piwi protein. This enabled maternally deposited Piwi to be cleared from newly laid embryos within 30 min and well ahead of the activation of zygotic transcription. Examination of RNA and protein profiles over time, and correlation with patterns of H3K9me3 deposition, suggests a role for maternally deposited Piwi in attenuating zygotic transposon expression in somatic cells of the developing embryo. In particular, robust deposition of piRNAs targeting roo, an element whose expression is mainly restricted to embryonic development, results in the deposition of transient heterochromatic marks at active roo insertions. We hypothesize that roo, an extremely successful mobile element, may have adopted a lifestyle of expression in the embryonic soma to evade silencing in germ cells.
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Affiliation(s)
- Martin H Fabry
- CRUK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Federica A Falconio
- CRUK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Fadwa Joud
- CRUK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Emily K Lythgoe
- CRUK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Benjamin Czech
- CRUK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
| | - Gregory J Hannon
- CRUK Cambridge Institute, University of Cambridge, Li Ka Shing CentreCambridgeUnited Kingdom
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Moschetti R, Palazzo A, Lorusso P, Viggiano L, Massimiliano Marsano R. "What You Need, Baby, I Got It": Transposable Elements as Suppliers of Cis-Operating Sequences in Drosophila. BIOLOGY 2020; 9:E25. [PMID: 32028630 PMCID: PMC7168160 DOI: 10.3390/biology9020025] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2019] [Revised: 01/27/2020] [Accepted: 01/30/2020] [Indexed: 12/18/2022]
Abstract
Transposable elements (TEs) are constitutive components of both eukaryotic and prokaryotic genomes. The role of TEs in the evolution of genes and genomes has been widely assessed over the past years in a variety of model and non-model organisms. Drosophila is undoubtedly among the most powerful model organisms used for the purpose of studying the role of transposons and their effects on the stability and evolution of genes and genomes. Besides their most intuitive role as insertional mutagens, TEs can modify the transcriptional pattern of host genes by juxtaposing new cis-regulatory sequences. A key element of TE biology is that they carry transcriptional control elements that fine-tune the transcription of their own genes, but that can also perturb the transcriptional activity of neighboring host genes. From this perspective, the transposition-mediated modulation of gene expression is an important issue for the short-term adaptation of physiological functions to the environmental changes, and for long-term evolutionary changes. Here, we review the current literature concerning the regulatory and structural elements operating in cis provided by TEs in Drosophila. Furthermore, we highlight that, besides their influence on both TEs and host genes expression, they can affect the chromatin structure and epigenetic status as well as both the chromosome's structure and stability. It emerges that Drosophila is a good model organism to study the effect of TE-linked regulatory sequences, and it could help future studies on TE-host interactions in any complex eukaryotic genome.
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Affiliation(s)
- Roberta Moschetti
- Dipartimento di Biologia, Università degli Studi di Bari “Aldo Moro”, Via Orabona 4, 70125 Bari, Italy; (R.M.); (P.L.); (L.V.)
| | - Antonio Palazzo
- Laboratory of Translational Nanotechnology, “Istituto Tumori Giovanni Paolo II” I.R.C.C.S, Viale Orazio Flacco 65, 70125 Bari, Italy;
| | - Patrizio Lorusso
- Dipartimento di Biologia, Università degli Studi di Bari “Aldo Moro”, Via Orabona 4, 70125 Bari, Italy; (R.M.); (P.L.); (L.V.)
| | - Luigi Viggiano
- Dipartimento di Biologia, Università degli Studi di Bari “Aldo Moro”, Via Orabona 4, 70125 Bari, Italy; (R.M.); (P.L.); (L.V.)
| | - René Massimiliano Marsano
- Dipartimento di Biologia, Università degli Studi di Bari “Aldo Moro”, Via Orabona 4, 70125 Bari, Italy; (R.M.); (P.L.); (L.V.)
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Merenciano M, Ullastres A, de Cara MAR, Barrón MG, González J. Multiple Independent Retroelement Insertions in the Promoter of a Stress Response Gene Have Variable Molecular and Functional Effects in Drosophila. PLoS Genet 2016; 12:e1006249. [PMID: 27517860 PMCID: PMC4982627 DOI: 10.1371/journal.pgen.1006249] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Accepted: 07/18/2016] [Indexed: 12/20/2022] Open
Abstract
Promoters are structurally and functionally diverse gene regulatory regions. The presence or absence of sequence motifs and the spacing between the motifs defines the properties of promoters. Recent alternative promoter usage analyses in Drosophila melanogaster revealed that transposable elements significantly contribute to promote diversity. In this work, we analyzed in detail one of the transposable element insertions, named FBti0019985, that has been co-opted to drive expression of CG18446, a candidate stress response gene. We analyzed strains from different natural populations and we found that besides FBti0019985, there are another eight independent transposable elements inserted in the proximal promoter region of CG18446. All nine insertions are solo-LTRs that belong to the roo family. We analyzed the sequence of the nine roo insertions and we investigated whether the different insertions were functionally equivalent by performing 5'-RACE, gene expression, and cold-stress survival experiments. We found that different insertions have different molecular and functional consequences. The exact position where the transposable elements are inserted matters, as they all showed highly conserved sequences but only two of the analyzed insertions provided alternative transcription start sites, and only the FBti0019985 insertion consistently affects CG18446 expression. The phenotypic consequences of the different insertions also vary: only FBti0019985 was associated with cold-stress tolerance. Interestingly, the only previous report of transposable elements inserting repeatedly and independently in a promoter region in D. melanogaster, were also located upstream of a stress response gene. Our results suggest that functional validation of individual structural variants is needed to resolve the complexity of insertion clusters.
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Affiliation(s)
- Miriam Merenciano
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Barcelona. Spain
| | - Anna Ullastres
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Barcelona. Spain
| | - M. A. R. de Cara
- Laboratoire d’Eco-anthropologie et Ethnobiologie, UMR 7206, CNRS/MNHN/Universite Paris 7, Museum National d’Histoire Naturelle, F-75116 Paris, France
| | - Maite G. Barrón
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Barcelona. Spain
| | - Josefa González
- Institute of Evolutionary Biology (CSIC-Universitat Pompeu Fabra), Barcelona. Spain
- * E-mail:
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Henriet S, Sumic S, Doufoundou-Guilengui C, Jensen MF, Grandmougin C, Fal K, Thompson E, Volff JN, Chourrout D. Embryonic expression of endogenous retroviral RNAs in somatic tissues adjacent to the Oikopleura germline. Nucleic Acids Res 2015; 43:3701-11. [PMID: 25779047 PMCID: PMC4402516 DOI: 10.1093/nar/gkv169] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 02/20/2015] [Indexed: 11/19/2022] Open
Abstract
Selective pressure to maintain small genome size implies control of transposable elements, and most old classes of retrotransposons are indeed absent from the very compact genome of the tunicate Oikopleura dioica. Nonetheless, two families of retrotransposons are present, including the Tor elements. The gene organization within Tor elements is similar to that of LTR retrotransposons and retroviruses. In addition to gag and pol, many Tor elements carry a third gene encoding viral envelope-like proteins (Env) that may mediate infection. We show that the Tor family contains distinct classes of elements. In some classes, env mRNA is transcribed from the 5′LTR as in retroviruses. In others, env is transcribed from an additional promoter located downstream of the 5′LTR. Tor Env proteins are membrane-associated glycoproteins which exhibit some features of viral membrane fusion proteins. Whereas some elements are expressed in the adult testis, many others are specifically expressed in embryonic somatic cells adjacent to primordial germ cells. Such embryonic expression depends on determinants present in the Tor elements and not on their surrounding genomic environment. Our study shows that unusual modes of transcription and expression close to the germline may contribute to the proliferation of Tor elements.
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Affiliation(s)
- Simon Henriet
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Sara Sumic
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | | | - Marit Flo Jensen
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Camille Grandmougin
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Kateryna Fal
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
| | - Eric Thompson
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway Department of Biology, University of Bergen, Bergen, N-5020, Norway
| | - Jean-Nicolas Volff
- Institut de Génomique Fonctionnelle de Lyon, Ecole Normale Supérieure de Lyon - CNRS UMR 5242 - INRA USC 1370, Lyon, 69364 Lyon cedex 07, France
| | - Daniel Chourrout
- Sars International Centre for Marine Molecular Biology, University of Bergen, Bergen, N-5008, Norway
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Spirov AV, Zagriychuk EA, Holloway DM. Evolutionary Design of Gene Networks: Forced Evolution by Genomic Parasites. PARALLEL PROCESSING LETTERS 2015; 24. [PMID: 25558118 DOI: 10.1142/s0129626414400040] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
The co-evolution of species with their genomic parasites (transposons) is thought to be one of the primary ways of rewiring gene regulatory networks (GRNs). We develop a framework for conducting evolutionary computations (EC) using the transposon mechanism. We find that the selective pressure of transposons can speed evolutionary searches for solutions and lead to outgrowth of GRNs (through co-option of new genes to acquire insensitivity to the attacking transposons). We test the approach by finding GRNs which can solve a fundamental problem in developmental biology: how GRNs in early embryo development can robustly read maternal signaling gradients, despite continued attacks on the genome by transposons. We observed co-evolutionary oscillations in the abundance of particular GRNs and their transposons, reminiscent of predator-prey or host-parasite dynamics.
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Affiliation(s)
- A V Spirov
- Computer Science and CEWIT, SUNY Stony Brook, 1500 Stony Brook Road, Stony Brook, NY 11794, USA The Sechenov Institute of Evolutionary Physiology & Biochemistry, Thorez Pr. 44, St.-Petersburg, 2194223, Russia
| | - E A Zagriychuk
- The Sechenov Institute of Evolutionary Physiology & Biochemistry, Thorez Pr. 44, St.-Petersburg, 2194223, Russia
| | - D M Holloway
- Mathematics Department, British Columbia Institute of Technology, 3700 Willingdon Avenue, Burnaby, B.C., Canada, V5G 3H2
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Batut P, Dobin A, Plessy C, Carninci P, Gingeras TR. High-fidelity promoter profiling reveals widespread alternative promoter usage and transposon-driven developmental gene expression. Genome Res 2013; 23:169-80. [PMID: 22936248 PMCID: PMC3530677 DOI: 10.1101/gr.139618.112] [Citation(s) in RCA: 135] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2012] [Accepted: 08/29/2012] [Indexed: 12/20/2022]
Abstract
Many eukaryotic genes possess multiple alternative promoters with distinct expression specificities. Therefore, comprehensively annotating promoters and deciphering their individual regulatory dynamics is critical for gene expression profiling applications and for our understanding of regulatory complexity. We introduce RAMPAGE, a novel promoter activity profiling approach that combines extremely specific 5'-complete cDNA sequencing with an integrated data analysis workflow, to address the limitations of current techniques. RAMPAGE features a streamlined protocol for fast and easy generation of highly multiplexed sequencing libraries, offers very high transcription start site specificity, generates accurate and reproducible promoter expression measurements, and yields extensive transcript connectivity information through paired-end cDNA sequencing. We used RAMPAGE in a genome-wide study of promoter activity throughout 36 stages of the life cycle of Drosophila melanogaster, and describe here a comprehensive data set that represents the first available developmental time-course of promoter usage. We found that >40% of developmentally expressed genes have at least two promoters and that alternative promoters generally implement distinct regulatory programs. Transposable elements, long proposed to play a central role in the evolution of their host genomes through their ability to regulate gene expression, contribute at least 1300 promoters shaping the developmental transcriptome of D. melanogaster. Hundreds of these promoters drive the expression of annotated genes, and transposons often impart their own expression specificity upon the genes they regulate. These observations provide support for the theory that transposons may drive regulatory innovation through the distribution of stereotyped cis-regulatory modules throughout their host genomes.
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Affiliation(s)
- Philippe Batut
- Watson School of Biological Sciences, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York 11724, USA.
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Blauth ML, Bruno RV, Abdelhay E, Valente VLS. Spatiotemporal transcription of the P element and the 412 retrotransposon during embryogenesis of Drosophila melanogaster and D. willistoni. Genet Mol Biol 2012; 34:707-10. [PMID: 22215978 PMCID: PMC3229129 DOI: 10.1590/s1415-47572011005000047] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2010] [Accepted: 07/27/2011] [Indexed: 11/22/2022] Open
Abstract
Transposable elements (TEs) are mobile nucleotide sequences which, through changing position in host genomes, partake in important evolutionary processes. The expression patterns of two TEs, P element transposon and 412 retrotransposon, were investigated during Drosophila melanogaster and D. willistoni embryogenesis, by means of embryo hybridization using riboprobes. Spatiotemporal transcription patterns for both TEs were similar to those of developmental genes. Although the two species shared the same P element transcription pattern, this was not so with 412 retrotransposon. These findings suggest that the regulatory sequences involved in the initial development of Drosophila spp are located in the transposable element sequences, and differences, such as in this case of the 412 retrotransposon, lead to losses or changes in their transcription patterns.
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Affiliation(s)
- Monica Laner Blauth
- Departamento de Zoologia e Genética, Instituto de Biologia, Universidade Federal de Pelotas, Pelotas, RS, Brazil
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Lipatov M, Lenkov K, Petrov DA, Bergman CM. Paucity of chimeric gene-transposable element transcripts in the Drosophila melanogaster genome. BMC Biol 2005; 3:24. [PMID: 16283942 PMCID: PMC1308810 DOI: 10.1186/1741-7007-3-24] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2005] [Accepted: 11/12/2005] [Indexed: 11/27/2022] Open
Abstract
Background Recent analysis of the human and mouse genomes has shown that a substantial proportion of protein coding genes and cis-regulatory elements contain transposable element (TE) sequences, implicating TE domestication as a mechanism for the origin of genetic novelty. To understand the general role of TE domestication in eukaryotic genome evolution, it is important to assess the acquisition of functional TE sequences by host genomes in a variety of different species, and to understand in greater depth the population dynamics of these mutational events. Results Using an in silico screen for host genes that contain TE sequences, we identified a set of 63 mature "chimeric" transcripts supported by expressed sequence tag (EST) evidence in the Drosophila melanogaster genome. We found a paucity of chimeric TEs relative to expectations derived from non-chimeric TEs, indicating that the majority (~80%) of TEs that generate chimeric transcripts are deleterious and are not observed in the genome sequence. Using a pooled-PCR strategy to assay the presence of gene-TE chimeras in wild strains, we found that over half of the observed chimeric TE insertions are restricted to the sequenced strain, and ~15% are found at high frequencies in North American D. melanogaster populations. Estimated population frequencies of chimeric TEs did not differ significantly from non-chimeric TEs, suggesting that the distribution of fitness effects for the observed subset of chimeric TEs is indistinguishable from the general set of TEs in the genome sequence. Conclusion In contrast to mammalian genomes, we found that fewer than 1% of Drosophila genes produce mRNAs that include bona fide TE sequences. This observation can be explained by the results of our population genomic analysis, which indicates that most potential chimeric TEs in D. melanogaster are deleterious but that a small proportion may contribute to the evolution of novel gene sequences such as nested or intercalated gene structures. Our results highlight the need to establish the fixity of putative cases of TE domestication identified using genome sequences in order to demonstrate their functional importance, and reveal that the contribution of TE domestication to genome evolution may vary drastically among animal taxa.
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Affiliation(s)
- Mikhail Lipatov
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Kapa Lenkov
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Dmitri A Petrov
- Department of Biological Sciences, Stanford University, Stanford, CA 94305, USA
| | - Casey M Bergman
- Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, UK
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Puig M, Cáceres M, Ruiz A. Silencing of a gene adjacent to the breakpoint of a widespread Drosophila inversion by a transposon-induced antisense RNA. Proc Natl Acad Sci U S A 2004; 101:9013-8. [PMID: 15184654 PMCID: PMC428464 DOI: 10.1073/pnas.0403090101] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Adaptive changes in nature occur by a variety of mechanisms, and Drosophila chromosomal inversions was one of the first studied examples. However, the precise genetic causes of the adaptive value of inversions remain uncertain. Here we investigate the impact of the widespread inversion 2j of Drosophila buzzatii on the expression of the CG13617 gene, whose coding region is located only 12 bp away from the inversion proximal breakpoint. This gene is transcribed into a 2.3-kb mRNA present in all D. buzzatii developmental stages. More importantly, the expression level of CG13617 is reduced 5-fold in embryos of lines homozygous for the 2j inversion compared with lines without the inversion. An antisense RNA that originates in the Foldback-like transposon Kepler inserted at the breakpoint junction in all of the 2j lines and that forms duplexes with the CG13617 mRNA in 2j embryos is most likely responsible for the near silencing of the gene. Few examples of RNA interference caused by transposable elements (TEs) have been previously described, but this mechanism might be prevalent in many organisms and illustrates the potential of TEs as a major source of genetic variation. In addition, because chromosomal rearrangements are usually induced by TEs, position effects might be more common than previously recognized and contribute significantly to the evolutionary success of inversions.
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Affiliation(s)
- Marta Puig
- Departament de Genètica i de Microbiologia, Universitat Autònoma de Barcelona, 08193 Bellaterra, Barcelona, Spain
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Kerber B, Fellert S, Taubert H, Hoch M. Germ line and embryonic expression of Fex, a member of the Drosophila F-element retrotransposon family, is mediated by an internal cis-regulatory control region. Mol Cell Biol 1996; 16:2998-3007. [PMID: 8649411 PMCID: PMC231294 DOI: 10.1128/mcb.16.6.2998] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The F elements of Drosophila melanogaster belong to the superfamily of long interspersed nucleotide element retrotransposons. To date, F-element transcription has not been detected in flies. Here we describe the isolation of a member of the F-element family, termed Fex, which is transcribed in specific cells of the female and male germ lines and in various tissues during embryogenesis of D. melanogaster. Sequence analysis revealed that this element contains two complete open reading frames coding for a putative nucleic acid-binding protein and a putative reverse transcriptase. Functional analysis of the 5' region, using germ line transformation of Fex-lacZ reporter gene constructs, demonstrates that major aspects of tissue-specific Fex expression are controlled by internal cis-acting elements that lie in the putative coding region of open reading frame 1. These sequences mediate dynamic gene expression in eight expression domains during embryonic and germ line development. The capacity of the cis-regulatory region of the Fex element to mediate such complex expression patterns is unique among members of the long interspersed nucleotide element superfamily of retrotransposons and is reminiscent of regulatory regions of developmental control genes.
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Affiliation(s)
- B Kerber
- Abteilung Molekulare Entwicklungsbiologie, Max-Planck-Institut für Biophysikalische Chemie, Göttingen, Germany
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