Chlamydomonas reinhardtii exhibits stress memory in the accumulation of triacylglycerols induced by nitrogen deprivation

Abstract

Stress memory is a phenomenon whereby exposure to initial stress event influences a response to subsequent stress exposures. Studying stress memory is important to understand the cellular behaviour in dynamic environment, especially nowadays, in times with growing environmental instability. Stress memory has been characterized in vascular plants but its occurrence in non-vascular plant species has been rarely investigated. We hypothesized that stress memory occurs in non-vascular plants in relation to metabolic stress. We sought to test it using accumulation of lipids (triacylglycerols) in model green alga Chlamydomonas reinhardtii subjected to nitrogen deprivation stress as a model system. Here, we established stress memory protocol on C. reinhardtii cells. Using a blend of microscopy and gas chromatography methods, we showed that the cells exposed to recurrent stress show differential accumulation of triacylglycerols on the quantitative level without qualitative changes in lipid composition, comparing to single stress controls. Overall, our results suggest that metabolic stress memory does occur in non-vascular plant C. reinhardtii and provides a starting point to characterize metabolic stress memory mechanism. Due to the commercial potential of algae, our findings are relevant for basic science, as well as industrial production of algae-derived compounds.

Strong confinement of active microalgae leads to inversion of vortex flow and enhanced mixing

“…They are considered next-generation resources for wastewater remediation and synthesis of biofuel, biocatalysts, and pharmaceuticals (Hoh et al, 2016;Khan et al, 2018). Recently, extreme confinement between two hard walls has been exploited to induce stress memory in CR cells towards enhanced biomass production and cell viability (Min et al, 2014;Mikulski and Santos-Aberturas, 2021).…”

“…They are considered next-generation resources for wastewater remediation and synthesis of biofuel, biocatalysts, and pharmaceuticals ( Hoh et al, 2016 ; Khan et al, 2018 ). Recently, extreme confinement between two hard walls has been exploited to induce stress memory in CR cells towards enhanced biomass production and cell viability ( Min et al, 2014 ; Mikulski and Santos-Aberturas, 2021 ). Despite the existing and emerging contexts outlined above, knowledge about how rigid walls might modify the kinetics, kinematics, fluid flow and mixing, and theoretical description of a strongly confined microalga such as CR (or any other microswimmer) is scarce.…”