Effect of Temperature on the Fluidity and Ordering of the Rod Outer Segment Membrane of Gekko Gekko

Abstract

The lateral diffusion of rhodopsin molecules in Gekko gekko rod outer segment (ROS) membranes was measured by microspectrophotometry (MSP) after the retinas were pretreated at different temperatures. It was found that the fluidity of ROS membrane was the smallest after it had been pretreated at 45° C. Correspondingly, the ordering of ROS lipids, as measured by their birefringence under a polarizing microscope, was observed after the ROS were pretreated at various temperatures. The birefrigence turned from positive to negative when the temperature of the treatment was higher than 46.5° C. These observations suggest that some sort of irreversible phase transition in the ROS membrane at about 45° C takes place.