ORCID Profile
0000-0001-7970-1667
Current Organisation
EPFL Life science
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Publisher: Springer Science and Business Media LLC
Date: 27-07-2015
DOI: 10.1038/NCOMMS8829
Abstract: Gut immunocompetence involves immune, stress and regenerative processes. To investigate the determinants underlying inter-in idual variation in gut immunocompetence, we perform enteric infection of 140 Drosophila lines with the entomopathogenic bacterium Pseudomonas entomophila and observe extensive variation in survival. Using genome-wide association analysis, we identify several novel immune modulators. Transcriptional profiling further shows that the intestinal molecular state differs between resistant and susceptible lines, already before infection, with one transcriptional module involving genes linked to reactive oxygen species (ROS) metabolism contributing to this difference. This genetic and molecular variation is physiologically manifested in lower ROS activity, lower susceptibility to ROS-inducing agent, faster pathogen clearance and higher stem cell activity in resistant versus susceptible lines. This study provides novel insights into the determinants underlying population-level variability in gut immunocompetence, revealing how relatively minor, but systematic genetic and transcriptional variation can mediate overt physiological differences that determine enteric infection susceptibility.
Publisher: American Society for Microbiology
Date: 07-09-2016
Abstract: Spiroplasma bacteria are highly motile bacteria with no cell wall and a helical morphology. This clade includes many vertically transmitted insect endosymbionts, including Spiroplasma poulsonii , a natural endosymbiont of Drosophila melanogaster . S. poulsonii bacteria are mainly found in the hemolymph of infected female flies and exhibit efficient vertical transmission from mother to offspring. As is the case for many facultative endosymbionts, S. poulsonii can manipulate the reproduction of its host in particular, S. poulsonii induces male killing in Drosophila melanogaster . Here, we analyze the morphology of S. poulsonii obtained from the hemolymph of infected Drosophila . This endosymbiont was not only found as long helical filaments, as previously described, but was also found in a Y-shaped form. The use of electron microscopy, immunogold staining of the FtsZ protein, and antibiotic treatment unambiguously linked the Y shape of S. poulsonii to cell ision. Observation of the Y shape in another Spiroplasma , S. citri , and anecdotic observations from the literature suggest that cell ision by longitudinal scission might be prevalent in the Spiroplasma clade. Our study is the first to report the Y-shape mode of cell ision in an endosymbiotic bacterium and adds Spiroplasma to the so far limited group of bacteria known to utilize this cell ision mode. IMPORTANCE Most bacteria rely on binary fission, which involves elongation of the bacteria and DNA replication, followed by splitting into two parts. Ex les of bacteria with a Y-shape longitudinal scission remain scarce. Here, we report that Spiroplasma poulsonii , an endosymbiotic bacterium living inside the fruit fly Drosophila melanogaster , ide with the longitudinal mode of cell ision. Observations of the Y shape in another Spiroplasma , S. citri , suggest that this mode of scission might be prevalent in the Spiroplasma clade. Spiroplasma bacteria are wall-less bacteria with a distinctive helical shape, and these bacteria are always associated with arthropods, notably insects. Our study raises the hypothesis that this mode of cell ision by longitudinal scission could be linked to the symbiotic mode of life of these bacteria.
Publisher: Wiley
Date: 26-07-2023
DOI: 10.1002/PROT.26545
Abstract: We present an in‐depth analysis of selected CASP15 targets, focusing on their biological and functional significance. The authors of the structures identify and discuss key protein features and evaluate how effectively these aspects were captured in the submitted predictions. While the overall ability to predict three‐dimensional protein structures continues to impress, reproducing uncommon features not previously observed in experimental structures is still a challenge. Furthermore, instances with conformational flexibility and large multimeric complexes highlight the need for novel scoring strategies to better emphasize biologically relevant structural regions. Looking ahead, closer integration of computational and experimental techniques will play a key role in determining the next challenges to be unraveled in the field of structural molecular biology.
No related grants have been discovered for Bruno Lemaitre.