Comparison of the nuclear DNA stability against freezing-thawing and high temperature treatments between spermatozoa and somatic cells.

Thermostability of sperm genome against freezing-thawing and high temperature treatments was assessed by comparing the degradation patterns of genomic DNAs from epididymal sperms and somatic tissues. Golden hamster liver, kidney, epididymal sperm, and testis were frozen and thawed repeatedly, or incubated in a hot water bath. Genomic DNAs were isolated and then separated by agarose gel electrophoresis. It was revealed that the size of sperm genomic DNA was hardly changed after freezing-thawing treatment, however, the DNA sizes of the other three tissues were gradually reduced with an increasing number of freezing-thawing cycles. In contrast, high temperature treatment appears to damage not only the genomic DNAs of somatic cells but also those of spermatozoa.