CHANGES IN MEMBRANE-PROTEINS OF CAUDA SPERMATOZOA OF GOAT BUCKS DURING IN-VITRO CAPACITATION

Sperm membrane (SM) proteins from in vitro capacitated and acrosome-re acted (AR) cauda spermatozoa of goat bucks were extracted with 1.0% Br ij-35, deoxycholate and saponin. Spermatozoa showed capacitation after 3 h in BWW medium (pH 7.4, containing 3% BSA and 10 mM Ca2+. The AR o ccurred by sequential shrinkage/decondensation of acrosomal contents, vesiculation and acrosome shedding, with concomitant release of SM pro teins into the medium. Lesser amounts of SM proteins extracted from ca pacitated spermatozoa indicated their release during AR. Polyacrylamid e gel electrophoresis pattern indicated that proteins/glycoproteins of low/high molecular weight were released and those with relatively hig her molecular weight were preferentially retained in the membranes dur ing AR. Glycoprotein nature of the released components indicated their membrane origin. Preferential retention of high molecular weight glyc oproteins indicated that these were deeply embedded in membranes. The immunodiffusion with heteroantisera Ig against testicular cells and ep ididymal spermatozoal extracts demonstrated removal of 140-160 kDa sur face antigens during AR. Membrane extracts of capacitated spermatozoa did not reach with Ig from isoantisera raised against caput and cauda spermatozoa. The acrosome reaction in bucks involves sequential shrink age/decondensation, vesiculation, shedding of acrosomal membranes and membrane proteins. Such proteins may be involved in fertilization.