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bioRxiv · 10.1101/319517

Phenotypic variability in chloroplast redox state predicts cell fate in a marine diatom

Mizrachi, A.·Graff van Creveld, S.·Shapiro, O. H.·Rosenwasser, S.·Vardi, A.
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Abstract

Diatoms are photosynthetic microorganisms of great ecological and biogeochemical importance, forming vast blooms in diverse aquatic ecosystems. Current understanding of phytoplankton acclimation to stress is based on population-level analysis, masking cell-to-cell variability. Here we investigated heterogeneity within Phaeodactylum tricornutum populations in response to oxidative stress, which is induced by environmental stress conditions. We combined flow cytometry and a microfluidics system for live imaging to measure redox dynamics at the single-cell level using the roGFP sensor. Chloroplast-targeted roGFP exhibited a light-dependent, bi-stable oxidation pattern in response to H2O2, revealing distinct subpopulations of sensitive oxidized cells and resilient reduced cells. Subpopulation proportions depended on growth phase, linking the bi-stable phenotype to proliferation. Oxidation of chloroplast-targeted roGFP preceded commitment to cell death and was used as a novel cell fate predictor. We propose that light-dependent metabolic heterogeneity results in differential stress responses that regulate cell fate within diatom populations.

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Mizrachi, A., Graff van Creveld, S., Shapiro, O. H., Rosenwasser, S., Vardi, A.. 2018-05-10. Phenotypic variability in chloroplast redox state predicts cell fate in a marine diatom. https://doi.org/10.1101/319517

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