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Étude des bases moléculaires de l’adaptation et de l’acclimatation aux changements environnementaux chez les picocyanobactéries marines, des organismes clés du phytoplancton

Abstract : The two marine picocyanobacteria Prochlorococcus and Synechococcus are the most abundant photosynthetic organisms on the planet, their wide distribution being probably linked to their large genomic diversity. The first part of my work has consisted in studying the genetic bases of the adaptation of these organisms to distinct ecological niches and revealed, by comparing 81 genomes of these two genera, the role of gene gains/losses and variations in nucleotide sequences in the diversification of these organisms. A second part has consisted in the analysis of the physiological responses of a Synechococcus model strain (WH7803) and of four other strains, representative of the dominant ecotypes in the field (clades I to IV), to various environmental factors in order to identify the genes that are involved in specific or common responses to these different stresses and/or ecotypes. Finally, the last part of my thesis aimed at identifying the distribution of all picocyanobacterial genes in the world ocean and to link it to environmental parameters and to the distribution of ecotypes, which made it possible to highlight the gene repertoires specific of niches and/or ecotypes. The integration of these results led me to get a better understanding of the adaptation and acclimation mechanisms, which allowed marine picocyanobacteria to colonize virtually all lit ecological niches of the oceans.
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Submitted on : Thursday, June 30, 2022 - 1:02:27 AM
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GUYET_Ulysse_2020.pdf
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  • HAL Id : tel-03709569, version 1

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Ulysse Guyet. Étude des bases moléculaires de l’adaptation et de l’acclimatation aux changements environnementaux chez les picocyanobactéries marines, des organismes clés du phytoplancton. Bio-informatique [q-bio.QM]. Sorbonne Université, 2020. Français. ⟨NNT : 2020SORUS185⟩. ⟨tel-03709569⟩

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