Exposure of cells to ionizing radiation alters cellular membranes leading to changes in membrane fluidity, transport, electrokinetic properties and surface topography. Radiation-induced changes in membranes derive from autocatalyzed oxidation of unsaturated lipids which modify membrane structure/function. This can cause cell death by impairing permeselectivity of cellular membrane barriers, distorting nuclear-cytoplasmic exchange, and by direct nuclear damage. This program aims to evaluate (i) cell survival and (ii) structure/fluidity of plasma and nuclear membranes isolated from Chinese hamster cells (V79), as a function of membrane composition and exposure to low-dose ionizing radiation. We will evaluate the role of membrane components that vary with diet and are known to affect membrane structure, namely (1) Cis-trans unsaturated fatty acids; (2) cholesterol and derivatives; (3) vitamin A and analogs; (4) vitamin E. Cell survival will be determined by clonogenic assays. Membrane structure/composition changes will be followed by Raman spectroscopy and biochemical methods.