Abstract

Sterols are critical components of eukaryotic membranes, regulating fluidity, permeability, and the activity of membrane-bound proteins. Their distribution and content within different cellular membranes, such as the plasma membrane (PM) and the tonoplast (vacuolar membrane), are dynamically regulated, particularly in response to environmental stressors. This study investigates the comparative changes in sterol content within the PM and tonoplast under two distinct, yet physiologically relevant, stress conditions: oxidative stress and osmotic stress. Using a combination of differential centrifugation and advanced lipidomics techniques, we quantified the sterol profiles of isolated PM and tonoplast fractions from a model organism. Our results indicate a differential response, with oxidative stress primarily inducing a significant increase in total sterol content in the PM, suggesting a compensatory mechanism to maintain membrane integrity. Conversely, osmotic stress led to a more pronounced, rapid decrease in sterol-to-lipid ratio in the tonoplast, potentially altering vacuolar function and turgor regulation. These findings highlight the distinct roles of the PM and tonoplast in cellular stress adaptation and provide novel insights into the membrane-specific lipid remodeling pathways crucial for cell survival under adverse environmental conditions.