EFFECTS OF SEMEN EXTENDER SUPPLEMENTED WITH L-METHIONINE AND PACKAGING METHODS (STRAWS AND PELLETS) ON POST-THAW GOLDFISH (Carassius auratus) SPERM QUALITY AND DNA DAMAGE

BACKGROUND

Amino acids protect spermatozoa against cell damage during cryopreservation due to have antioxidant property and found in seminal plasma at high concentration.

OBJECTIVE

The aim of the present work was to analyse the effect of extender supplementation with L-methionine on post-thawed sperm motility, duration and DNA damage and also it was tested the feasibility of using straws and pellets method for the cryopreservation of goldfish (Carassius auratus) sperm.

MATERIALS AND METHODS

Extenders were supplemented with different L-methionine concentrations of 1 mM; 1.5 mM; 3 mM; 6 mM. Semen samples diluted at the ratio of 1 to 9 by the extenders were subjected to cryopreservation. After dilution the semen was aspirated into 0.25 ml straws and 0.1 ml pellets, the straws and pellets were placed on the tray, frozen in nitrogen vapor and plunged into liquid nitrogen. DNA damage was determined with comet assay after cryopreservation.

RESULTS

Our results indicated that an increase in the concentration of L-methionine caused a significant increase in the motility rate and duration of sperm in goldfish (C. auratus) (p<0.05). In addition, duration and percentage of motility in pellets were higher than in straws. Comparing all concentrations of L-methionine, the best concentration of L-methionine was 1.5 mM. Highest post-thaw motility (45.00 +/- 7.07%) and duration of motility (17.00 +/- 0.71s) were obtained with the extender at concentration 1.5 mM in pellets. Addition of the extender with L-methionine was reduced DNA damage compared to control group.

CONCLUSION

Consequently, pellets could be used for goldfish sperm cryopreservation and the tested amino acid affected the motility parameters, and semen extenders could be supplement with L-methionine.

Effect of butylated hydroxytoluene (BHT) on the cryopreservation of common carp (Cyprinus carpio) spermatozoa

The aim of the present study was to test the effects of butylated hydroxytoluene (BHT) on the cryopreservation of common carp spermatozoa. BHT is widely used in the cryopreservation of the spermatozoa of different animal species and successfully sustains the characteristics of spermatozoa during freezing and thawing, but it has not previously been used with fish. After sampling, common carp spermatozoa were diluted with an extender composed of modified Kurokura's extender, 10% DMSO, and 10% egg yolk containing 0.0001, 0.001, 0.01, 0.1, 1, 2.5, 5, or 10mM BHT and subsequently frozen in liquid nitrogen. The post-thaw spermatozoa characteristics (i.e., progressive motility percentage (%), duration of progressive motility (s), fertilization rate (%), and eyed-eggs rate (%)) were evaluated and compared with those of the control group. There were significant increases in the percentage of progressive motility and the duration of progressive motility at the concentrations of 0.1 and 0.001mM BHT (P<0.05). The duration of post-thawed spermatozoa progressive motility at 0.001mM BHT was significantly greater than that of the other groups (39.6±0.4s, P<0.05), and the fertilization rates and eyed-eggs rates were also higher following the 0.1 and 1mM BHT treatments. BHT at concentrations of more than 1mM caused sperm immobility during the preparatory stages of the sperm freezing. We concluded that 0.001-0.1mM BHT can be beneficial for the cryopreservation of common spermatozoa.