Freeze fracturing properties of native and heat-adapted Chinese hamster ovary (CHO) cells

Abstract

Chinese hamster ovary cells were either maintained at 37 °C (native cells) or heat adapted by exposure to a temperature of 40 °C for 2 h. Thereafter, native and heat-adapted cells were incubated at different temperatures for various times, harvested, fixed with glutaraldehyde and glycerol, and studied by freeze fracture microscopy. We observed that the fracture plane either passed through the cell, exposing cytoplasm, or stayed within the plasma membrane, and that the location of the fracture plane was strongly determined by the previous thermal history of the cell. We believe that these differences reflect changes in membrane lipid packing arrangements.Key words: freeze fracture, heat adaptation, Chinese hamster ovary cells.