Motility and oxidative-antioxidant capacity of Huso huso semen, stored at -80°C.

In this study, motility and oxidative-antioxidant capacity (thiobarbituric acid-reactive substance level [TBARS], superoxide dismutase [SOD], catalase [CAT] and glutathione reductase [GR]) of beluga sturgeon (Huso huso) sperm, stored for 6 days at -80°C, were evaluated. After 2 days of storage, sperm motility was significantly decreased (no motile sperm were observed after 6 days of storage; p < .05), while TBARS and SOD values were significantly increased (p < .05). CAT and GR activities did not show significant changes among storage times (p > .05). Furthermore, all investigated parameters showed a significant difference between semen stored at 4°C (control) and -80°C during in vitro storage (p < .05). Data from this work can potentially be useful in sturgeon sperm cryobanking.

Influence of Glutamine Supplementation on Motility and Fertilization Success of Frozen-Thawed Persian Sturgeon (Acipenser persicus) Sperm.

Amino acids have an important biological role for the prevention of cell damage during cryopreservation. The aim of this study was to investigate the effects of glutamine on post-thaw sperm motility and fertilization success in the Persian sturgeon (Acipenser persicus). Sperm collected from six fish was cryopreserved in extenders containing different glutamine concentrations (2.5, 5 and 10 mm). Sperm samples diluted at the ratio of 1 : 1 using the extenders were subjected to cryopreservation. After dilution, the sperm suspensions were sucked into 250-µl straws; the straws were placed on the tray, frozen in nitrogen vapour and plunged into liquid nitrogen. Then, sperm were thawed in a water bath at 40°C for 5 s and used for analysis. Our results revealed that an increase in the concentration of glutamine caused a significant increase in the motility percentage, curvilinear velocity (VCL) and also fertilization success in the Persian sturgeon (p < 0.05). Comparing all concentrations of glutamine, the best concentration for sperm motility and fertilization rate was 10 mm. In addition, higher post-thaw motility percentage, VCL, and fertilization and hatching rates were obtained with the extender at the concentration of 10 mm (p < 0.05). The findings of this study showed that glutamine was of greater benefit to Persian sturgeon sperm motility during frozen-thawed process.

Effect of post-thaw storage time on motility and fertility of cryopreserved beluga sturgeon (Huso huso) sperm.

The aim of this study was to test the influence of post-thaw storage time on the duration of sperm motility, percentage of motile sperm, and fertilization and hatching rates of fresh sperm and sperm stored for 0, 30 and 60 min at 4°C post-thawing. After being frozen in liquid nitrogen and then thawed, the percentage of motile sperm and duration of motility were not affected by 30 min of storage at 4°C, whereas a significant decline in these parameters was observed after 60 min of storage. Similarly, fertilization and hatching rates were significantly affected within 60 min of storage at 4°C, and the fertility of frozen-thawed sperm was significantly lower than that of fresh sperm. We conclude that cryopreserved sperm of beluga sturgeon could be stored for 30 min without the loss of sperm quality. This described procedure for beluga sturgeon cryopreservation is reliable and efficient and therefore can be recommended for hatchery practice after scaling up this technique.

Study of sperm concentration, seminal plasma composition and their physiological correlation in the Persian sturgeon, Acipenser persicus.

The objectives of the present study were to determine ionic and organic composition of seminal plasma, sperm concentration and their relationships in the Persian sturgeon (Acipenser persicus). In this regard, ionic content (Na(+) , K(+) , Cl(-) , Ca(2+) and Mg(2+) ) and organic content (total protein, glucose, cholesterol and triglyceride) along with sperm concentration were measured in 17 specimens of the Persian sturgeon. The seminal plasma contained 59.53 ± 2.56 mm/l sodium, 9.1 ± 1.42 mm chloride, 4.72 ± 0.3 mm potassium, 1.45 ± 0.075 mm calcium and 0.7 ± 0.072 mm magnesium. The following organic contents were found: total protein 0.11 ± 0.02 g/dl, glucose 22.18 ± 4.16 mg/dl, cholesterol 6.67 ± 1.04 mg/dl and triglyceride 15.2 ± 0.65 mg/dl. The mean sperm concentration was estimated to be 1.6 ± 0.12 (×10(9)  sperm/ml). A significant relationship was found between sperm concentration and K(+) of seminal plasma (r = 0.533, p < 0.05). Significant correlations were observed between ionic contents: Na(+) vs Cl(-) (r = -0.854, p < 0.01) and Mg(2+) vs K(+) (-0.583, p < 0.05). Also, level of triglyceride was negatively correlated with Mg(2+) (r = -0.503, p < 0.05). Presented data could be considered as a complementary study for developing special extenders and protectant solutions for improving artificial fertilization in this valuable species.