CRYOPRESERVATION OF GOLDFISH (Carassius auratus) SPERMATOZOA: EFFECTS OF EXTENDER SUPPLEMENTED WITH TAURINE ON SPERM MOTILITY AND DNA DAMAGE.

BACKGROUND: Amino acids, present in seminal plasma at high concentration, protect spermatozoa against cell damage during cryopreservation. OBJECTIVE: Experiments were designed to analyze the effect of semen extender supplemented with taurine on post-thawed sperm motility and duration, as well as DNA damage. MATERIALS AND METHODS: Extenders were supplemented with 1, 2 or 4 mM taurine. Semen samples were diluted at the ratio of 1:9 with the extenders. Diluted samples were aspirated into 0.25 ml French straws and 0.1 ml pellets. DNA damage was assessed with the comet assay after cryopreservation. RESULTS: The percentage and duration of sperm motility were significantly increased by taurine. Additionally, sperm motility and the motility period in pellets were higher than in straws. The best concentration of taurine was 4 mM, and the highest post-thaw motility rate (72.50 ± 3.54 %) and duration (17.50 ± 0.71 s) were obtained from the extender with 4 mM in pellets. DNA damage was decreased after taurine supplementation. CONCLUSION: Pellets could be used for goldfish sperm cryopreservation. The addition of 4 mM taurine increases the post-thaw motility and decreases DNA damage on goldfish semen.

Effect of semen extender supplementation with cysteine on postthaw sperm quality, DNA damage, and fertilizing ability in the common carp (Cyprinus carpio).

Amino acids have an important biological role for prevention of cell damage during cryopreservation. The objective of this study is to determine the effects of cysteine on postthaw sperm motility, duration of sperm motility, DNA damage, and fertility in the common carp (Cyprinus carpio). Sperm collected from 10 individuals was cryopreserved in extenders containing different cysteine concentrations (2.5, 5, 10, and 20 mM). Semen samples diluted at the ratio of 1:9 by the extenders were subjected to cryopreservation. After dilution, the semen was aspirated into 0.25-mL straws; the straws were placed on the tray, frozen in nitrogen vapor, and plunged into liquid nitrogen. DNA damage was evaluated by comet assay after cryopreservation. Our results indicated that an increase in the concentration of cysteine caused a significant increase in the motility rate and duration of sperm in the common carp (C carpio; P < 0.05). Comparing all concentrations of cysteine, the best concentration of cysteine was 20 mM. Higher postthaw motility (76.00 ± 1.00%) and fertilization (97.00 ± 1.73%) rates were obtained with the extender at the concentration of 20 mM. Supplementation of the extender with cysteine was increased the fertilization and hatching rate and decreased DNA damage. Consequently, cysteine affected the motility, fertilization, and DNA damage positively, and extenders could be supplemented with cysteine.

Cryopreservation of rainbow trout Oncorhynchus mykiss spermatozoa: effects of extender supplemented with different antioxidants on sperm motility, velocity and fertility.

In present study, it was examined whether addition of different antioxidants to the cryopreservation extenders had an effect on semen post-thaw fertility and motility in rainbow trout (Oncorhynchus mykiss) and also it was investigated the sperm characteristics post-thaw sperm characteristics and fertility. The collected semen was pooled to minimize individual variation. Each pooled ejaculate was split into 12 equal aliquots and diluted with base extenders supplemented with the antioxidants, and a base extender with no additives (control). The pooled semen samples diluted at the ratio of 1:10 by the extenders were subjected to cryopreservation. Antioxidants were separately added to the extenders (one per experimental group): catalase (250 U/l), superoxide dismutase (250 U/l), peroxidase (250 U/l), oxidized glutathione (1.5 mmol/l), reduced glutathione (1.5 mmol/l), L-methionine (1.5 mmol/l), uric acid (0.25 mmol/l), L-ascorbic acid (0.5 mmol/l), α-tocopherol (2.0 mmol/l), ß-carotene (0.5 mmol/l) and carnitine (0.5 mmol/l). After dilution the semen was aspirated into 0.25 ml straws, the straws were placed on the tray, frozen for 10 min, and plunged into liquid nitrogen. Our results indicated that the post-thaw motility rate increased in extenders supplemented with uric acid, L-methionine, SOD, L-carnitine, α-tocopherol and L-reduced glutathione (p<0.05). The motility duration of frozen thawed semen increased in extenders supplemented with uric acid, L-methionine, SOD, α-tocopherol and L-reduced glutathione (p<0.05). Fertilization rate and hatching rate of frozen-thawed semen was not affected by the tested antioxidants. Consequently, the tested antioxidants affected the motility parameters and cryopreservation extenders could be supplement with antioxidants. This study suggested usage of antioxidants in the cryopreservation of rainbow trout.