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Cellular and molecular characterization of Ostreopsis cf. ovata cell cycle

Abstract : Ostreopsis cf. ovata is a cosmopolitan toxic dinoflagellate that produces seasonal blooms. It is currently unknown how this organism divides or how its cell cycle is controlled. The aim of this thesis was to provide a cellular and molecular characterization of the mitotic cell cycle, which underlies cell proliferation during vegetative growth, for the dinoflagellate O. cf. ovata. Morphological classification of cells collected at different phases of the bloom, allowed to identify different phases of the O. cf. ovata vegetative cycle, including cells undergoing division. Using this classification, I showed that during blooming, O. cf. ovata divides exclusively at night. Using immuno-fluorescence and confocal microscopy, I then characterized the major changes in cytoskeletal organization associated with the O. cf. ovata cell cycle. To characterize O. cf. ovata cell cycle at the molecular level, I searched for O. cf. ovata homologues of conserved cell cycle regulators identified in model organisms, using a de novo transcriptome that I generated from cultured cells. This analysis revealed the presence of major components of the O. cf. ovata cell cycle. A differential expression analysis using meta-trascriptomic datasets corresponding to bloom samples enriched in interphase cells, pre-dividing cells and dividing, which I generated during the 2019 bloom, showed an active transcriptional control during cell division. By integrating the results obtained from the transcriptomic analysis with the cytological characterization I propose a first model of O. cf. ovata cell cycle, in which cyclins and CDK activities dictate the transition from interphase to mitosis.
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Submitted on : Wednesday, September 7, 2022 - 11:52:33 AM
Last modification on : Thursday, September 8, 2022 - 3:53:50 AM

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  • HAL Id : tel-03771330, version 1

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David Velasquez Carvajal. Cellular and molecular characterization of Ostreopsis cf. ovata cell cycle. Cellular Biology. Sorbonne Université, 2021. English. ⟨NNT : 2021SORUS458⟩. ⟨tel-03771330⟩

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