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Contrôle génétique de l'établissement et de la plasticité de la pigmentation abdominale chez Drosophila melanogaster

Abstract : Phenotypic plasticity is the ability of a given genotype to produce different phenotypes in response to different environmental factors such as temperature, nutrition or presence of predators. This phenomenon allows the adaptation of individuals to their fluctuating environments. It can also facilitate evolution, as it broadens the range of phenotypes produced by a given genotype. As a model of phenotypic plasticity, we study the abdominal pigmentation in Drosophila melanogaster females. Indeed, this trait is temperature-sensitive: drosophila females are darker when they develop at lower temperatures particularly in the posterior segments. In the laboratory, it has been previously shown, that tan (t), a gene encoding a pigmentation enzyme, is more expressed at 18°C than at 29°C. Moreover, this gene plays an essential role in the phenotypic plasticity of abdominal pigmentation in Drosophila melanogaster females. During my thesis, I aimed to characterize the gene regulatory network involved in t regulation in the abdominal epidermis of Drosophila melanogaster females. I also tried to identify, in this network, the actors mediating the effect of temperature on t expression. Using a candidate gene approach, I showed that the transcription factors Bric-à-brac (Bab) and Abdominal-B (Abd-B) are involved in the phenotypic plasticity of abdominal pigmentation by regulating t. Furthermore, I performed a genetic screen targeting 573 genes encoding transcription factors and chromatin regulators to identify new regulators of t. At the end of this screen, I obtained a list of 27 genes involved in this regulation. I then started the functional characterization of two of these candidates: forkhead box subgroup O (foxo) encoding a transcription factor involved in the insulin response pathway and little imaginal discs (lid) encoding a histone demethylase.
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https://tel.archives-ouvertes.fr/tel-02406359
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Submitted on : Thursday, December 12, 2019 - 9:42:41 AM
Last modification on : Monday, August 31, 2020 - 12:36:02 PM
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  • HAL Id : tel-02406359, version 1

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Sandra Silva de Castro. Contrôle génétique de l'établissement et de la plasticité de la pigmentation abdominale chez Drosophila melanogaster. Génétique animale. Sorbonne Université, 2018. Français. ⟨NNT : 2018SORUS320⟩. ⟨tel-02406359⟩

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