Changes in the properties of the surface membrane of schistosoma mansoni during growth as measured by fluorescence recovery after photobleaching

Abstract

Schistosomiasis is a widespread tropical disease of human beings. Infection occurs when a free-living, water-borne cercaria penetrates the skin, becomes transformed into a schistosomulum which then migrates through the blood stream of the host to develop into an adult parasite in the portal blood sys- tem [ 11. The surface membrane of both the schisto- somulum and adult worm is unusual; it is a double bilayer, and forms a continuous surface covering the peripheral syncytium [2]. The properties of this membrane change during growth and development in the host so that it becomes progressively less suscepti- ble to damage by a variety of agents [3-81. An under- standing of the nature of these changes is sought in the hope that immunological control or chemotherapy of the disease may be made more effective. The tech- nique of fluorescence recovery after photobleaching (FRAP) can measure the lateral diffusion of protein and lipid in the cell surface [9-131. We describe here its use in comparing the outer surfaces of the schisto- somulum and adult