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Characterization of the mechanisms underlying Drosophila growth promotion conferred by Lactobacillus plantarum

Abstract : Intestinal microbiota can modulate virtually all aspects of their host physiology, and particularly, digestion and metabolism. However, the molecular mechanisms at play remain largely unknown. To tackle this question, we use a simple gnotobiotic model: Drosophila larvae monoassociated with one of its major natural symbiont, Lactobacillus plantarum. Previous work from our group showed that L. plantarum promotes the juvenile growth of larvae facing a protein scarcity, thereby dampening the deleterious effect of the nutrient deficiency on larval growth. This growth enhancement partially relies on the upregulation of intestinal proteases, as well as on the modulation of the host TOR (Target Of Rapamycin) pathway by the symbionts. My thesis work aimed at unraveling other host genetic mechanisms involved in the interaction between Drosophila and L. plantarum during growth. Our work showed that host natural genomic variations affect the fly physiologic response to L. plantarum. Furthermore, the bases of our work enabled to unveil a novel role of intestinal bacteria, revealing their ability to act as a genetic buffer to compensate the growth impairments due to the fly genetic background. In addition, L. plantarum decreases the phenotypic variations in various host fitness traits (growth, organ size, timing to pupariation) and it also confers robustness to organ patterning. Finally, we showed that the TGF-β ligand, Dawdle plays an important regulatory role on digestive enzymes in a protein-deficient nutritional context, and that this regulation can be inhibitory or activating depending on the microbial environment.
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Claire-Emmanuelle Indelicato. Characterization of the mechanisms underlying Drosophila growth promotion conferred by Lactobacillus plantarum. Animal genetics. Université de Lyon, 2017. English. ⟨NNT : 2017LYSEN094⟩. ⟨tel-01827241⟩

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