Murathan Kayim

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), β-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.

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.

Seasonal variation in food preference of the brown trout Salmo trutta macrostigma (T., 1954) from Uzungöl Stream, Turkey

The present study is aimed to provide information on the abundance of natural foods of Salmo trutta macrostigma (T., 1954). Fish were captured from Uzungol Stream in Trabzon, Turkey between March 2009 and May 2010. It was investigated whether the dietary preferences of trout (S. t. macrostigma) change on account of seasons. Captured fish were measured 17.11 ± 4.65 cm (S.D.) (range 5 to 30 cm), 60.38 ± 48.52 g (S.D.) (range 2.34 to 250.84) (n = 163), respectively. The condition factor of trout calculated 1.00 ± 0.5 (S.D.) (range 0.57 to 1.58) (n = 163). The age range was between 0 and 8 years old. Stomach contents were analyzed using two methods, the frequency of occurrence and numerical method. A total of 11 prey groups were identified in the diets of brown trout living in Uzungol Stream.Prey groups were consisted of Trichoptera, Clitellata, unidentified Insecta, Coleoptera, Ephemeroptera, Haplotaxidae, Diptera, Verenoide, Plecoptera, Hymenoptera and Arachnidae. Analyses of stomach contents showed that the trout feed basically on Arthropoda and Annelidae. Seasonal variation of different food items showed that a high percentage of occurrence of Clitellata were recorded during both winter and autumn, while the highest percent of Coleoptera occurred during summer. Key words: Uzungol stream, Salmo trutta macrostigma, stomach contents, frequency of occurrence, numerical method, seasonal variations.