Abdou Akkouche

Claude Bernard University Lyon 1, Villeurbanne, Rhône-Alpes, France

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Publications (4)18.16 Total impact

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    ABSTRACT: piRNAs (piwi-interacting RNAs) are a class of small interfering RNAs that play a major role in the regulation of transposable elements (TEs) in Drosophila and are considered of fundamental importance in gonadal development. Genes encoding the effectors of the piRNA machinery are thus often though to be highly constrained. On the contrary, as actors of genetic immunity, these genes have also been shown to evolve rapidly and display a high level of sequence variability. In order to assess the support for these competing models, we analyzed seven genes of the piRNA pathway using a collection of wild-type strains of Drosophila simulans, which are known to display significant variability in their TE content between strains. We showed that these genes exhibited wide variation in transcript levels, and we discuss some evolutionary considerations regarding the observed variability in TE copy numbers.
    Gene 12/2013; DOI:10.1016/j.gene.2013.11.095 · 2.08 Impact Factor
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    ABSTRACT: Transposable elements (TEs), whose propagation can result in severe damage to the host genome, are silenced in the animal gonad by Piwi-interacting RNAs (piRNAs). piRNAs produced in the ovaries are deposited in the embryonic germline and initiate TE repression in the germline progeny. Whether the maternally transmitted piRNAs play a role in the silencing of somatic TEs is however unknown. Here we show that maternally transmitted piRNAs from the tirant retrotransposon in Drosophila are required for the somatic silencing of the TE and correlate with an increase in histone H3K9 trimethylation an active tirant copy.
    EMBO Reports 04/2013; 14(5). DOI:10.1038/embor.2013.38 · 7.86 Impact Factor
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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.
    Journal of Environmental Radioactivity 05/2012; 113:83-6. DOI:10.1016/j.jenvrad.2012.04.001 · 3.57 Impact Factor
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    ABSTRACT: Endogenous retroviruses have the ability to become permanently integrated into the genomes of their host, and they are generally transmitted vertically from parent to progeny. With the exception of gypsy, few endogenous retroviruses have been identified in insects. In this study, we describe the tirant endogenous retrovirus in a subset of Drosophila simulans natural populations. By focusing on the envelope gene, we show that the entire retroviral cycle (transcription, translation, and retrotransposition) can be completed for tirant within one population of this species.
    Journal of Virology 01/2012; 86(7):3675-81. DOI:10.1128/JVI.07146-11 · 4.65 Impact Factor

Publication Stats

17 Citations
18.16 Total Impact Points

Institutions

  • 2013
    • Claude Bernard University Lyon 1
      Villeurbanne, Rhône-Alpes, France
  • 2012–2013
    • University of Lyon
      Lyons, Rhône-Alpes, France
    • French National Centre for Scientific Research
      • Laboratoire de Biométrie et Biologie Évolutive (LBBE)
      Lyon, Rhone-Alpes, France