Cryopreservation of Mesopotamian catfish (Silurus triostegus H., 1843) spermatozoa: Effects of diluents and osmotic pressure on spermatozoa DNA damage, rate and duration of motility

Abstract

This study was performed to evaluate the effectiveness of three different osmotic pressure (325, 365, and 385 mOsm/kg) in combination with Dimethyl Sulfoxide (DMSO) and NaCl or glucose on spermatozoa DNA damage, rate and duration of motility. Sperm was collected from eight healthy mature Silurus triostegus, evaluated microscopically and pooled at 25 °C. The pooled sperm samples were diluted to final concentration of 1/3 (sperm/diluents) in NaCl and glucose based extender (10% cryoprotectant and 10% egg yolk (EY) into 80% diluents) and separated into groups to 3 different osmotic pressures (325-365-385 mOsm/ kg). Equilibrated sperm was frozen in 0.25 ml straws. Sperm samples were tested for post-thaw sperm motility, duration of motility, DNA damage, Apoptotic index.<br /> The highest spermatozoa motility rates were obtained with glucose and NaCl diluents at osmotic pressures of 365 and 385 mOsm/kg (p <0.01). The spermatozoa motility duration was found to be the highest in glucose and NaCl diluents at 365 mOsm/kg osmotic pressure (p <0.01). The post-thawing live spermatozoa rate was determined to be the highest in the sperm frozen with glucose at 385 mOsm/kg. The apoptotic cell rate was determined to be the highest in the sperm frozen with glucose at 385 mOsm/kg osmotic pressure. The necrotic cell rate was found to be the highest with 2.08±0.39% when frozen with the glucose diluent at 325 mOsm/kg pressures. It is concluded that the glucose solution with low osmolality had a harmful effect on the spermatozoa.