Seminal characteristics and sensitivity of astyanax lacustris (Characiformes: Characidae) sperm to cryoprotective solutions based on dimethylsufoxide and methylglicol

Abstract

This study aimed to determine the semen characteristics of Astyanax lacustris after hormonal induction and to evaluate the sensitivity of the species sperm to cryoprotective solutions based on the cryoprotectants dimethyl sulfoxide and methyl glycol. Volume, color, sperm concentration, total motility and aspects of sperm movement were analyzed using “Integrated Semen Analysis System”. Three different extenders were tested: A) glucose 5%+egg yolk 10%, B) BTS® 5% and C) glucose 5% and two permeable cryoprotectants: dimethyl sulfoxide (Me2 SO) and methyl glycol (MTG). Fresh A. lacustris semen presented total motility of 76.6±11.2%, motility duration of 33.0±2.2s, sperm concentration of 7.22±3.2×109sptz/mL and seminal osmolality of 219±0.03mOsm/ kg-1. The toxicity test showed the highest total motility values at the MTG15%+A, Me2 SO15%+B and Me2 SO10%+C dilutions, and the Me2 SO10%+C and Me2 SO15%+C dilutions presented the highest values for curvilinear velocity, linear velocity and average velocity. The tested protocol was not effective at maintaining the viability of A. lacustris semen after freezing because no motility was observed in any of the dilutions. However, the Comet Assay demonstrated that cryoprotectant solutions were effective in protecting the genetic material of cells, as DNA damage levels were low, with no difference between control and Me2 SO10% + A, dilutions MTG10%+C, Me2 SO10%+B and Me2 SO15%+B.