Shedding New Light into Lipid Oxidation in GUVs and Bacteria. From Membrane Dynamics to Cell Survival.

ANDRÉS M. DURANTINI; ISABEL O. L. BACELLAR; SOL R. MARTÍNEZ; GONZALO COSA

Córdoba

Conferencia; XIII Encuentro Latinoamericano de Fotoquímica y Fotobiología (XIII ELAFOT); 2017

Lipid oxidation is a ubiquitous process with important roles in cell biology and consequently in human health. Lipid oxidation may involve a chain autooxidation reaction, may takeplace via enzymatic pathways or via photooxidation. Chemical modifications tothe lipid molecule may be amplified as changes in collective physicalproperties such as lipid membrane surface area, thickness, porosity,permeability, and segregation. In this presentation,we will describe the use of fluorescence microscopy jointly with a fluorogenicα-tocopherol analogue probe previouslydeveloped by us (H2B-PMHC) to studyoxidation of lipid membranes in giant unilamellar vesicles (GUVs) mediated byphotoinduced generation of singlet oxygen (1O2).Fluorescence microscopy studies with 1O2 photosensitizerson single GUVs embedding H2B-PMHC illustrated rapid activation ofthe probe followed later by fluctuations of the lipid membrane and expansion. Acorrelation was observed between the time for antioxidant H2B-PMHCconsumption by 1O2 (directly related to the rate of lipidoxidation) and the onset of membrane fluctuations. We also expand our studiesfrom GUVs to bacteria where our microscopy tools enable us to illuminate thespatiotemporal ROS production due to oxidative stress induced by ciprofloxacinin individual bacteria. Discussion on the biological relevance of theseprocesses will be presented.