Maturation of mammalian spermatozoa in the male reproductive tract and their hyperactivation during capacitation in the female reproductive tract must occur for the spermatozoa to be capable of fertilization. These phenomena involve major changes in the movement of the sperm flagellum, brought about either by biochemical modification of the flagellar axoneme and/or accessory structures, or by changes in the intracellular environment in which the axoneme acts. The first overall objective of the proposed research is to develop improved procedures for the isolation of mammalian (ram) sperm flagella, and to purify and determine the protein composition of the dynein ATPases responsible for flagellar movement. The second long-term goal is to elucidate the sequence of events that result in the acquisition of the capacity for motility in sperm as they pass from the testis to the caudal epididymis. Demembranated ram rete testis sperms, which initially do not have the capacity for motility by acquire it upon incubation with cAMP, will be used in these studies. Experiments will be carried out to determine whether the acquisition of motility involves detergent-soluble protein factors, and if so, to purify them and determine how they work. The experiments will also determine which proteins of the axoneme and/or accessory structures are involved in the initiation of motility. The third overall goal is to elucidate the mechanism by which sperm become hyperactivated in the ampulla of the oviduct. The proposed studies will determine whether hyperactivation is induced by an increase in intracellular Ca++, as suggested by preliminary results, and will identify the proteins responsible for this phenomenon. The above studies will involve extensive light microscopic observation and analysis of flagellar waveforms under various conditions, as well as electron microscopic and biochemical characterization of sperm flagella fractions. Information gained from this research should ultimately lead to the development of new and highly specific pharmacological methods for inhibiting sperm motility in vivo, thereby preventing fertilization, and conversely, for correcting defects that result in abnormal sperm movement and infertility.
