Genomic environment influences the dynamics of the tirant LTR retrotransposon in Drosophila

Université Lyon 1, CNRS, UMR5558, Laboratoire de Biométrie et Biologie Evolutive, F-69622, Villeurbanne, France.
The FASEB Journal (Impact Factor: 5.04). 02/2009; 23(5):1482-9. DOI: 10.1096/fj.08-123513
Source: PubMed


Combining genome sequence analysis and functional analysis, we show that some full-length copies of tirant are present in heterochromatic regions in Drosophila simulans and that when tested in vitro, these copies have a functional promoter. However, when inserted in heterochromatic regions, tirant copies are inactive in vivo, and only transcription of euchromatic copies can be detected. Thus, our data indicate that the localization of the element is a hallmark of its activity in vivo and raise the question of genomic invasions by transposable elements and the importance of their genomic integration sites.

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Available from: Emmanuelle Lerat
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    • "In recent decades, several studies have revealed the extent of the participation of the environment in the expression and/or activation of retrotransposons in studies on various organisms such as plants,11,17 insects of the genus Drosophila,18 shrimp,14 fish19 and mice.20,21 Fish have a particularly large number of active retrotransposons, and many are unique to this group.22,23 "
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    ABSTRACT: Transposable elements (TEs) are DNA sequences that have the ability to move and replicate within the genomes. TEs can be classified according to their intermediates of transposition, RNA (retrotransposons) or DNA. In some aquatic organisms, it has been observed that environmental factors such as pH, temperature and pollution may stimulate differential transcription and mobilization of retrotransposons. In light of this information, the present study sought to evaluate the expression of Rex6 TE transcripts in Colossoma macropomum, which is a very commercially exploited fish in Brazil. In order to establish a comparative analysis using real-time PCR, the samples were collected from Amazonian rivers with different physical and chemical characteristics (distinguished by clear water and black water). Quantitative RT-PCR analyses revealed a differential pattern of expression between tissues collected from different types of water (clear and black waters). When it came to the hepatic and muscle tissues sampled, the levels of Rex6 transcripts were significantly different between the two Amazonian water types. These results suggest that environmental conditions operate differently in the regulation of Rex6 transcription in C. macropomum, results which have implications in the reshaping of the genome against environmental variations.
    Full-text · Article · Jul 2014
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    • "We know that TE sequences are sensitive to environmental stresses such as thermal changes, but little is know about the effects of radiation in TEs activity. By ChIP analyses, we were able to identify a complex pattern of chromatin conformation at TE loci, with active copies of tirant simultaneously displaying both activating and inhibiting histone marks (Fablet et al., 2009). More importantly, we also observed intra-and inter-species variations in the pattern of histone marks that adorn the copies of three LTR-retrotransposons (412, roo, and tirant), and one LINE-like element (F) in populations of D. melanogaster and D. simulans (unpublished data). "
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    ABSTRACT: Genes are important in defining genetic variability, but they do not constitute the largest component of genomes, which in most organisms contain large amounts of various repeated sequences including transposable elements (TEs), which have been shown to account for most of the genome size. TEs contribute to genetic diversity by their mutational potential as a result of their ability to insert into genes or gene regulator regions, to promote chromosomal rearrangements, and to interfere with gene networks. Also, TEs may be activated by environmental stresses (such as temperature or radiation) that interfere with epigenetic regulation systems, and makes them powerful mutation agents in nature. To understand the relationship between genotype and phenotype, we need to analyze the portions of the genome corresponding to TEs in great detail, and to decipher their relationships with the genes. For this purpose, we carried out comparative analyses of various natural populations of the closely-related species Drosophila melanogaster and Drosophila simulans, which differ with regard to their TE amounts as well as their ecology and population size.
    Full-text · Article · May 2012 · Journal of Environmental Radioactivity
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    ABSTRACT: Transposable elements (TEs) are responsible for rapid genome remodelling by the creation of new regulatory gene networks and chromosome restructuring. TEs are often regulated by the host through epigenetic systems, but environmental changes can lead to physiological and, therefore, epigenetic stress, which disrupt the tight control of TEs. The resulting TE mobilization drives genome restructuring that may sometimes provide the host with an innovative genetic escape route. We suggest that macroevolution and speciation might therefore originate when the host relaxes its epigenetic control of TEs. To understand the impact of TEs and their importance in host genome evolution, it is essential to study TE epigenetic variation in natural populations. We propose to focus on recent data that demonstrate the correlation between changes in the epigenetic control of TEs in species/populations and genome evolution.
    Full-text · Article · Apr 2010 · Gene
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