@article {uwizeye_cytoklepty_2021,
	title = {Cytoklepty in the plankton: A host strategy to optimize the bioenergetic machinery of endosymbiotic algae},
	journal = {Proceedings of the National Academy of Sciences},
	volume = {118},
	number = {27},
	year = {2021},
	note = {Publisher: National Academy of Sciences Section: Biological Sciences},
	month = {jul},
	abstract = {Endosymbioses have shaped the evolutionary trajectory of life and remain ecologically important. Investigating oceanic photosymbioses can illuminate how algal endosymbionts are energetically exploited by their heterotrophic hosts and inform on putative initial steps of plastid acquisition in eukaryotes. By combining three-dimensional subcellular imaging with photophysiology, carbon flux imaging, and transcriptomics, we show that cell division of endosymbionts (Phaeocystis) is blocked within hosts (Acantharia) and that their cellular architecture and bioenergetic machinery are radically altered. Transcriptional evidence indicates that a nutrient-independent mechanism prevents symbiont cell division and decouples nuclear and plastid division. As endosymbiont plastids proliferate, the volume of the photosynthetic machinery volume increases 100-fold in correlation with the expansion of a reticular mitochondrial network in close proximity to plastids. Photosynthetic efficiency tends to increase with cell size, and photon propagation modeling indicates that the networked mitochondrial architecture enhances light capture. This is accompanied by 150-fold higher carbon uptake and up-regulation of genes involved in photosynthesis and carbon fixation, which, in conjunction with a ca.15-fold size increase of pyrenoids demonstrates enhanced primary production in symbiosis. Mass spectrometry imaging revealed major carbon allocation to plastids and transfer to the host cell. As in most photosymbioses, microalgae are contained within a host phagosome (symbiosome), but here, the phagosome invaginates into enlarged microalgal cells, perhaps to optimize metabolic exchange. This observation adds evidence that the algal metamorphosis is irreversible. Hosts, therefore, trigger and benefit from major bioenergetic remodeling of symbiotic microalgae with potential consequences for the oceanic carbon cycle. Unlike other photosymbioses, this interaction represents a so-called cytoklepty, which is a putative initial step toward plastid acquisition.},
	keywords = {3D electron microscopy, oceanic plankton, Photosynthesis, rcc, rcc1383, single-cell transcriptomics, symbiosis},
	issn = {0027-8424, 1091-6490},
	doi = {10.1073/pnas.2025252118},
	url = {https://www.pnas.org/content/118/27/e2025252118},
	author = {Uwizeye, Clarisse and Brisbin, Margaret Mars and Gallet, Benoit and Chevalier, Fabien and LeKieffre, Charlotte and Schieber, Nicole L. and Falconet, Denis and Wangpraseurt, Daniel and Schertel, Lukas and Stryhanyuk, Hryhoriy and Musat, Niculina and Mitarai, Satoshi and Schwab, Yannick and Finazzi, Giovanni and Decelle, Johan}
}
@article {uwizeye_morphological_2021,
	title = {Morphological bases of phytoplankton energy management and physiological responses unveiled by 3D subcellular imaging},
	journal = {Nature Communications},
	volume = {12},
	number = {1},
	year = {2021},
	note = {Number: 1 Publisher: Nature Publishing Group},
	month = {feb},
	pages = {1{\textendash}12},
	abstract = {Phytoplankton account for a large proportion of global primary production and comprise a number of phylogenetically distinct lineages. Here, Uwizeye et al. use FIB-SEM to study ultrastructural plasticity of 7 distinct taxa and describe how subcellular organisation is linked to energy metabolism.},
	keywords = {RCC100, RCC4014, RCC827, RCC909},
	issn = {2041-1723},
	doi = {10.1038/s41467-021-21314-0},
	url = {http://www.nature.com/articles/s41467-021-21314-0},
	author = {Uwizeye, Clarisse and Decelle, Johan and Jouneau, Pierre-Henri and Flori, Serena and Gallet, Benoit and Keck, Jean-baptiste and Bo, Davide Dal and Moriscot, Christine and Seydoux, Claire and Chevalier, Fabien and Schieber, Nicole L. and Templin, Rachel and Allorent, Guillaume and Courtois, Florence and Curien, Gilles and Schwab, Yannick and Schoehn, Guy and Zeeman, Samuel C. and Falconet, Denis and Finazzi, Giovanni}
}
@article {Uwizeye2020,
	title = {In-cell quantitative structural imaging of phytoplankton using 3D electron microscopy},
	journal = {bioRxiv},
	year = {2020},
	note = {tex.mendeley-tags: RCC100,RCC4014,RCC827,RCC909},
	month = {jan},
	pages = {2020.05.19.104166},
	abstract = {Phytoplankton is a minor fraction of the global biomass playing a major role in primary production and climate. Despite improved understanding of phytoplankton diversity and genomics, we lack nanoscale subcellular imaging approaches to understand their physiology and cell biology. Here, we present a complete Focused Ion Beam - Scanning Electron Microscopy (FIB-SEM) workflow (from sample preparation to image processing) to generate nanometric 3D phytoplankton models. Tomograms of entire cells, representatives of six ecologically-successful phytoplankton unicellular eukaryotes, were used for quantitative morphometric analysis. Besides lineage-specific cellular architectures, we observed common features related to cellular energy management: i) conserved cell-volume fractions occupied by the different organelles; ii) consistent plastid-mitochondria interactions, iii) constant volumetric ratios in these energy-producing organelles. We revealed detailed subcellular features related to chromatin organization and to biomineralization. Overall, this approach opens new perspectives to study phytoplankton acclimation responses to abiotic and biotic factors at a relevant biological scale.Competing Interest StatementThe authors have declared no competing interest.},
	keywords = {RCC100, RCC4014, RCC827, RCC909},
	doi = {10.1101/2020.05.19.104166},
	url = {http://biorxiv.org/content/early/2020/05/20/2020.05.19.104166.abstract},
	author = {Uwizeye, Clarisse and Decelle, Johan and Jouneau, Pierre-Henri and Gallet, Benoit and Keck, Jean-baptiste and Schwab, Yannick and Schoehn, Guy and Zeeman, Samuel C and Falconet, Denis and Finazzi, Giovanni and Moriscot, Christine and Chevalier, Fabien and Schieber, Nicole L and Templin, Rachel and Curien, Gilles and Schwab, Yannick and Schoehn, Guy and Zeeman, Samuel C and Falconet, Denis and Finazzi, Giovanni}
}
