Protein concentration and enzyme activities of fresh and frozen–thawed Persian sturgeon, Acipenser persicus (Borodin, 1897) semen

The membrane integrity of fish spermatozoa can be compromised after exposure to a freeze–thaw cycle, resulting in leakage of proteins in the seminal fluid. In the present work, the total protein concentration (TP) and enzyme activities of acid phosphatase (AcP), lactate dehydrogenase (LDH), arylsulfatase (AS), b-Nacetylglucosaminidase (b-N-AGase) were measured in seminal plasma of fresh and freeze–thawed semen of Persian sturgeon (Acipenser persicus Borodin). The enzyme activity of fresh and frozen–thawed seminal plasma was as: AcP (0.59 ± 0.035 and 9.89 ± 0.81), LDH (484.4 ± 27.3 and 6,262.7 ± 263.2), AS (169.1 ± 44.4 and 699.6 ± 25.1), b-N-AGase (36.31 ± 2.25 and 70.7 ± 2.24), respectively, in fresh and freeze–thawed sperm. The TP semen content in fresh semen was 0.28 ± 0.031 and in frozen–thawed was 1.68 ± 0.1. The results indicate that TP concentration and activities of AcP, LDH, AS, and b-N-AGase were significantly higher in frozen–thawed seminal plasma. For this reason, these molecules may be used as markers for estimation of membrane damage of spermatozoa exposed to freeze–thaw cycle.