Abstract: Comet assay was used to detect DNA integrity of paddlefish(Polyodon spathula) sperm following cryopreservation. At the same time, sperm velocities prior to freezing and postthawing were also assessed by the computer-assisted sperm analysis (CASA) system. Significant differences (P < 0.05) were detected in the degree of DNA damage in cryopreserved sperm using different extenders. According to osmolality of the extenders, DNA damages of Sb (20 mM Tris, 75 mM sucrose, 0.5 mM KCl, pH 8.5) sperm was the least, which showed that the percentage of tail DNA of Sb (17.87–35.28%) was lower than those of Sa (20 mM Tris, 50 mM sucrose, 0.5 mM KCl, pH 8.5) and Sc (20 mM Tris, 100 mM sucrose, 0.5 mM KCl, pH 8.5). Moreover, A and B class sperm cells provided most of the Sb sperm (>50%).However, in light of the concentration of methanol, DNA damages of M8 (8% methanol concentration) sperm were the least, including a lower percentage of the tail DNA (21.56–30.86%), and C and D class sperm cells (<30%), regardless of the osmolality of the extenders. In conclusion, when the dilution was 20 mM Tris, 75 mM sucrose, 0.5 mM KCl, pH8.5 and the concentration of methanol was 8%, the extenders were the best for cryopreservation of paddlefish sperm. In addition, the results indicated that the extent of damage to sperm motility caused by freeze-thawing (VCL, VSL) was correlated with DNA breakage (|r| > 0.8). This implied that cryopreservation could damage sperm DNA of paddlefish and affect the sperm velocities when the osmolality and the concentrations of the cryoprotectants of the extender were inappropriate.

附件下载：P.Li, Q.Wei, L.Liu. DNA integrity of Polyodon spathula cryopreserved sperm. J.Appl. Ichthyol. 2008, 24: 121-125. pdf