Acrosin activity in turkey spermatozoa assay by clinical method and effectof zinc and benzamidine on the activity

We optimized a clinical assay developed for measuring total acrosin activit y for mammalian and fish semen for use in turkey spermatozoa. The main modi fications included dilution of semen to a final concentration of 25 to 1000 x 10(3) spermatozoa, an increase of Triton X-100 concentration to 0.05% an d 1 hr preincubation without substrate. Acrosin activity in turkey spermato zoa was much higher than in human spermatozoa (about 100-times) but similar to that of boar sperm, To optimize this assay for turkey spermatozoa, it w as necessary to use higher Triton X-100 concentrations in the reaction mixt ure. There was a better catalytic efficiency at higher temperatures and a s pecial requirement for a preincubation period for proacrosin activation. We observed high inhibition of acrosin activity by zinc added during preincub ation (90% at 0.01 mM of zinc chloride). Benzamidine also inhibited turkey acrosin, and the extent of inhibition was similar for the incubation or pre incubation period. When zinc ions were added during incubation, this inhibi tion was lower (24%). The results suggest that zinc influences proacrosin a ctivation of turkey spermatozoa. This influence may be important for succes sful long-term storage of spermatozoa in the hen's oviduct. (C) 2001 by Els evier Science Inc.