Oxidative stress in plant lipid membranes: An electro-biophysical approach

CORVALÁN, NATALIA A. ; CAVIGLIA, AGUSTÍN ; ENET, ALEJANDRO; FELSZTYNA, IVÁN; LASCANO, HERNÁN R.

Santos

Congreso; XLII Congresso da Sociedade Brasileira de Biofísica; 2017

Sociedade Brasileira de Biofísica

OXIDATIVE STRESS IN PLANT LIPID MEMBRANES: An electro-biophysical approachEnvironmental stress conditions, such as strong light, drought, salinity, heat, and cold, which all promotean exacerbated reactive oxygen species (ROS) production, represent risk factors to cellular redoxhomeostasis. Depending on the severity of stress, namely, the intensity and duration of stressconditions, a delicate balance between cell death and signaling will take place. This implies a dual role ofROS, as toxic or as signaling molecules, since they are able to modulate defense responses, acclimation,growth and development, and cell death by oxidative reactions. ROS are different activation states of O 2 ,as singlet oxygen ( 1 O 2 ), or reduction states, as superoxide radical (O 2 - ), hydrogen peroxide (H 2 O 2 ) andhydroxyl radical (·OH), being this latter highly toxic to cellular metabolism because its high reactivity todifferent macromolecules. Cell membrane systems, whose integrity is crucial to the plant physiology, areone of the main targets of oxidative processes mediated by ROS. These chemical species interact withunsaturated fatty acids of membrane lipids triggering a peroxidation chain reaction to produce lipidhydroperoxides in a process known as lipoperoxidation (LPO). But how crucial are the electro-biophysical membrane changes induced by LPO to the cell, or how these changes modulate cellularresponse and ?susceptibility? to environmental physical-chemical signals, or how membranefunctionality is affected by membrane lipid order changes remain poorly understood. In the presentwork, a thorough analysis of the electro-biophysical properties of planar lipid bilayers (BLMs) composedof a complex mixture of purified lipids from Plasma Membrane of soybean leaves (Glycine max L) wasperformed under different stress conditions with the aim of improving our understanding of the basicunderlying processes of oxidative membrane damage that occur when plants are subjected tounfavorable environmental conditions. Oxidative treatments with different types (hydrogen peroxideand hydroxyl radical) and ROS concentrations were applied. Our preliminary results show MembraneCapacitance (C) as a critical order and structural parameter which shows a nonlinear increment (biphasicbehavior) in response to thresholds of ROS concentrations and exposure time to ROS. Moreover, abruptchanges (transitions) in membrane resistance and conductance occur associated to capacitance changeswhen BLM soy are subjected to oxidative treatments. Taking into account C depends on membrane area(A), and the molecular area and fluctuations increase in oxidized lipids, capacitive behavior would seemrespond to structural and organizational changes induced by oxidative damage and be able to modulateelectrical membrane properties, and in consequence, signaling processes at cellular level.