Güneş Yamaner

Volume changes during the motility period of fish spermatozoa: Interspecies differences

The aim of this study was to describe spermatozoa volume changes during the motility period of fish species with either osmotic (common carp Cyprinus carpio) or with ionic (sterlet Acipenseri ruthenus and brook trout Salvelinus fontinalis) modes of motility activation. Nephelometry, light microscopy, and spermatocrit methods were used for quantitative assessment of cell volume changes in media of different osmolalities. Significant correlation (R(2) = 0.7341; P < 0.001) between parameter of volume changes measured using nephelometry and light microscopy methods confirmed nephelometry as a sufficiently sensitive method to detect changes of spermatozoa volume. The spermatocrit alteration method resulted in a large proportion of damaged and potentially immotile spermatozoa in media of osmolality less than 150 mOsm/kg in carp and osmolalities from 10 to 300 mOsm/kg in sterlet and brook trout. Therefore, this method is not reliable for assessing spermatozoa swelling in hypotonic solutions, because the integrity of the cells is not fully preserved. Increase in carp spermatozoa (osmotic activation mode) volume occurred during the motility period in hypotonic conditions, but no indications of volume changes were found in sterlet and brook trout spermatozoa (ionic activation mode) associated with environmental osmolality alteration. Accordingly, we conclude that sperm volume changes are differentially involved in the motility activation process. Species-specific differences in spermatozoa volume changes as a response to a hypotonic environment during the motility period are discussed in relation to their potent physiological role.

Effects of Different Doses of Taurine in the Glucose-Based Extender During Cryopreservation of Rainbow Trout (Oncorhynchus Mykiss) Semen

ABSTRACT This study aimed to investigate the effects of different doses of taurine added to glucose extender. Semen was collected from rainbow trout (Oncorhynchus mykiss) by abdominal massage and diluted (1:2) with 300 mM glucose (G) extender containing different taurine doses (50, 75 and 100 mM). The control group extender did not contain taurine. After dilution and dosing, samples were filled to 0.5 ml straws, frozen in nitrogen vapour and stored in liquid nitrogen. The comparison of the results obtained for the 50 mM taurine group and the control group showed no significant difference between the post-thawing motility percentages and motility duration of sperm, and only a very low statistically difference for eyed-embryo percentages (P < 0.05).

Hypotonic treatment prior to freezing improves cryoresistance of common carp (Cyprinus carpio L.) spermatozoa.

Post-thaw motility rate, curvilinear velocity (VCL), and fertilizing ability of carp spermatozoa can be improved by short-term treatment with moderately hypotonic media prior to freezing. Before cryopreservation, carp sperm samples were treated with NaCl solutions of differing osmolalities, ranging from 100 to 300mOsmkg(-1) for 10s, after which final osmolality was adjusted to 300mOsmkg(-1). The resulting sperm suspension was diluted 1:1 with cryoprotective medium and frozen using conventional techniques. Control samples were treated in the same way, without the pre-dilution step. Post-thaw motility rate in samples pretreated with 200mOsmkg(1) NaCl was significantly higher (44±10%) than in controls (21±15%) and samples pretreated with 100mOsmkg(-1) (25±15%) and 300mOsmkg(-1) (25±12%) NaCl. Significantly higher mean VCL were observed in samples pretreated with 100, 150, and 200mOsmkg(-1) (119±24, 118±22, and 115±32μms(-1), respectively) compared to controls (92±27μms(-1)). Fertilization rate of frozen-thawed sperm treated with 200mOsmkg(-1) solution of 2M NaCl was significantly higher (25±18%) than that of sperm treated with 300mOsmkg(-1) NaCl solutions (12±7%) and the control (9±6%).

Determination of sex and gonad maturity in sturgeon (Acipenser gueldenstaedtii) using ultrasound technique

ABSTRACT This study was conducted to investigate the sex and gonad stage of Russian sturgeons (Acipenser gueldenstaedtii) under natural water conditions in concrete ponds through the use of ultrasound technique. The ultrasound technique was effective in determining sturgeon gender. However, because the ultrasound showed that males were ready to produce viable sperm but females were not ready to produce eggs in autumn, it is clear that another ultrasound examination would be needed during the breeding season to identify females with mature eggs to ensure fertilization success.