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Le plaste des diatomées : centre énergétique et cible des interactions allélopathiques

Abstract : One of the major forces that shape the dynamics and structure of phytoplankton communities is the direct inhibition of the metabolism of competitors thanks to the use of secondary metabolites. But our understanding of this phenomenon, called allelopathy, remains limited. Photosynthesis is an ideal probe to study allelopathic interactions between marine microalgae, simply because it is one of the main targets. We have validated a new approach allowing to dissect the photosynthetic activities of each microalgae within a mixture, allowing to reveal allelopathic interactions affecting photosynthesis. This thesis focuses on diatoms plastid which, beyond being the energetic center of the cell, also proves to be a specific target of the allelochemical compounds released by their competitors.This methodological approach made it possible to demonstrate the inhibition of the photosynthetic activity of the diatom T. pseudonana by allelochemical compounds released by the dinoflagellate A. carterae. This inhibition involves the dissipation of the electrochemical proton gradient across the thylakoids, probably by amphidinol-like molecules forming pores on biological membranes. We were also able to show two other allelopathic interactions targeting the plastid of diatoms: the role of alkyl-quinolones, released by bacteria, on the photosynthetic and respiratory electron transport chains of the diatom P. tricornutum, and the effects of the filtrate of the dinoflagellate A. minutum on the cytoplasmic and plastid membranes of the diatom C. muelleri.
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Submitted on : Tuesday, August 31, 2021 - 11:15:27 AM
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  • HAL Id : tel-03329733, version 1

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Alexandra Peltekis. Le plaste des diatomées : centre énergétique et cible des interactions allélopathiques. Interactions entre organismes. Sorbonne Université, 2020. Français. ⟨NNT : 2020SORUS174⟩. ⟨tel-03329733⟩

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