Retracted: Study of enzyme activities and protein content of beluga (Huso huso) semen before and after cryopreservation

Knowledge gained regarding the biochemical processes that occur during sperm collection, processing and freezing‐thawing might improve current sperm cryopreservation techniques. In our present study, we determined the effect of cryopreservation on the total protein concentration (TP) and the activities of certain enzymes in semen samples from the beluga (Huso huso). The TP content of the seminal plasma of fresh semen was 0.47 ± 0.026 g/l, and the TP after cryopreservation was 1.86 ± 0.6 g/l. The activities of acid phosphatase (0.82 ± 0.042 U/l), lactate dehydrogenase (234.4 ± 19.4 U/l), arylsulfatase (143.1 ± 32.5 U/l) and β‐N‐acetylglucosaminidase (58.39 ± 4.14 U/l) in the seminal plasma of fresh semen were significantly lower than those in the supernatant of frozen‐thawed semen samples (7.43 ± 0.64, 3224.6 ± 167.2, 422.6 ± 21.3 and 90.2 ± 5.37 U/l respectively). These parameters may be useful as biomarkers for estimating damage to the cell membrane of spermatozoa caused by freezing‐thawing.