Characteristics of sperm acrosin-like activity of paddlefish (Polyodon spathula Walbaum)

Spermatozoa of paddlefish and sturgeon fishes (Acipenseriformes), unlike te leost fish, have an acrosome. The objectives of this study were to characte rize acrosin-like activity of cryopreserved sperm of paddlefish (Polyodon s pathula) and to test and compare stability of paddlefish acrosin-like activ ity with that of lake sturgeon and bull spermatozoa. Mean acrosin-like acti vity of cryopreserved paddlefish sperm was 0.372 +/- 0.067 mu U/10(6) sperm atozoa. This activity was 79% higher in the whole semen than in spermatozoa . Highest activity was recorded at pH 8.0 and 8.5. Triton X-100, zinc ions and 4'-acetamidophenyl 4-guanidinobenzoate (AGB) inhibited the activity. Am idase activity was also inhibited by N-alpha-p-tosyl-L-lysine chloromethyl ketone (TLCK) and N-tosyl-L-phenylalanine chloromethyl ketone (TPCK). TLCK at concentrations of 0.1 and 1.0 mM gave a significant decrease in activity of 19 and 61%, respectively. However, TPCK significantly inhibited amidase activity (by 19%) only at concentration 1.0 mM. After acidification and 60 min incubation at 4 degrees C of sperm suspensions only 4% of the activity was retained. A similar phenomenon was observed in the case of lake sturge on but not bull sperm. These results suggest that trypsin-like activity of Acipenserid fish resembles rather fish trypsin that mammalian one. In froze n-thawed paddlefish sperm a minute chymotrypsin-like activity was also indi cated, when GPNA was used as substrate. This activity amounted to 0.0415 +/ - 0.0138 mu U/10(6) spermatozoa and was 18% of total amidase activity. This suggests that chymotrypsin-like activity may also be present in paddlefish spermatozoa. (C) 2000 Elsevier Science Inc. All rights reserved.