DNA Fragmentation, Linear Velocity and Fertilising Ability of Reactivated Cryopreserved Goldfish Sperm using Different Cryoprotectants

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 (Me2SO) 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, Me2SO15%+B and Me2SO10%+C dilutions, and the Me2SO10%+C and Me2SO15%+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 Me2SO10% + A, dilutions MTG10%+C, Me2SO10%+B and Me2SO15%+B.

Effects of cooling rates on the quality of Prochilodus lineatus (Valenciennes, 1836) sperm

This study aims to investigate the effect of different cooling rates on the semen cryopreservation of curimba (Prochilodus lineatus). Nineteen ejaculates were obtained from adults males and cryopreserved at 15°C/min (CR15), 30°C/min (CR30) (controlled temperature inside and outside straw, speed was stable during freezing) and direct freezing in liquid nitrogen vapour (~35.6°C/min) (CRNV). The straws were thawed and seminal parameters evaluated. DNA fragmentation through the comet assay was assessed. A fresh sperm sample was not frozen and used for analyses. Data were submitted to an analysis of variance (ANOVA), and means were compared by Scott-Knott test (p < 0.05) using the R Software. Mean motility percentage was 100%, and motility duration was 39.5 ± 5.7 s for the fresh sperm (subjective analysis); 58.9 ± 8.0% and 24.5 ± 5.7 s for CR15; 64.8 ± 4.8% and 26.5 ± 7.1 s for CR30; and 50.1 ± 16% and 25.7 ± 4.7 s for CRNV, respectively. Motility percentages were higher and equal between CR15 and CR30 compared to CRNV (p < 0.05). Some sperm motion kinetics, namely average path velocity (VAP) and straight line velocity (VAS), were higher for CR30 (p < 0.05), while curvilinear velocity (VCL) and velocity progression (PRO) were lower for CRNV (p < 0.05). Straightness (STR) and wobble (WOB) were the same among treatments (p > 0.05). Sperm morphology results indicated higher means for total morphological sperm alterations in CRNV. All cooling rates caused sperm DNA fragmentation, although CR30 provided a less harmful effect. This is the first report for cryopreserved P. lineatus sperm preserved under different controlled cooling rates. The cooling rate of 30°C/min is indicated for the cryopreservation of this fish sperm as it led to the lowest detrimental spermatozoa effects.

DNA fragmentation and membrane damage of bocachico Prochilodus magdalenae (Ostariophysi: Prochilodontidae) sperm following cryopreservation with dimethylsulfoxide and glucose

The endangered bocachico Prochilodus magdalenae is a native freshwater fish of Colombia, the most captured species locally and one of the most important species for ex-situ conservation (germplasm banks). The aim of this study was to examine the effect of three concentrations of Dimethylsulfoxide (DMSO) (5%, 10%, 15%) and three of glucose (305, 333, 361 mM) in the extender on spermatic DNA fragmentation (F-DNA) (by Halomax®, Chromatin dispersion) and membrane damage (D-Me) (by eosin-nigrosin staining). After assessment of sperm quality by computer analysis of motility, one part of semen from males was diluted separately with three parts of extender and filled into 0.5 ml straws. Freezing was carried out in liquid nitrogen vapor dry shipper for 30 minutes and thawed at 60ºC for 8 seconds in a water bath and evaluated for the percentage of cells found with F-DNA and D-Me. The results demonstrated that cryopreservation causes greater F-DNA (13.62 ± 1.6% to 28.91 ± 3.25) and D-Me (24.27 ± 1.1% to 58.33 ± 2.81%) when compared with pre-freezing semen (PFS) (6.71 ± 1.54% and 2.34 ± 0.5%, respectively for F-DNA and D-Me). A significant interaction was found between DMSO and glucose concentration in this experiment. Use of extender: 10% DMSO + 305 mM glucose + 12% chicken egg yolk and, 10% DMSO + 333 mM glucose + 12% chicken egg yolk, allow for lower F-DNA and D-Me during cryopreservation of bocachico semen. A high correlation between F-DNA and D-Me was found (r = 0.771).