Sailer B L, Jost L K, Evenson D P
South Dakota State University, Olson Biochemistry Laboratories, Brookings, USA.
J Androl. 1995 Jan-Feb;16(1):80-7.
Sperm from four mammalian species were analyzed by the sperm chromatin structure assay (SCSA) and the terminal deoxynucleotidyl transferase assay (TdTA) using flow cytometry. The SCSA quantitates the susceptibility of sperm nuclear DNA to in situ acid denaturation, while the TdTA quantitates the presence of endogenous DNA strand breaks in sperm nuclear chromatin. Correlations were seen between the percentage of sperm cells showing susceptibility to in situ acid denaturation and the percentage of cells showing the presence of DNA strand breaks for humans (r = 0.56, P = 0.004), rams (r = 0.84, P < 0.001), bulls (r = 0.78, P < 0.001), and stallions (r = 0.65, P < 0.001). No significant differences were seen when using fresh or frozen samples for either assay. These results suggest that sperm cells that are more susceptible to in situ DNA denaturation may have a greater number of accessible endogenous DNA strand breaks. We hypothesize that the DNA strand breaks produced in the normal transition from a somatic cell histone complex to a protamine complex are not ligated properly, resulting in residual DNA strand breaks and altered chromatin structure. Alternatively, altered chromatin structure could lead to the accessibility of the endogenous DNA strand breaks.
使用流式细胞术通过精子染色质结构分析（SCSA）和末端脱氧核苷酸转移酶分析（TdTA）对四种哺乳动物的精子进行了分析。SCSA定量精子核DNA对原位酸变性的敏感性，而TdTA定量精子核染色质中内源性DNA链断裂的存在情况。在显示对原位酸变性敏感的精子细胞百分比与显示存在DNA链断裂的细胞百分比之间，观察到人类（r = 0.56，P = 0.004）、公羊（r = 0.84，P < 0.001）、公牛（r = 0.78，P < 0.001）和种马（r = 0.65，P < 0.001）之间存在相关性。对于任何一种分析，使用新鲜或冷冻样品时均未观察到显著差异。这些结果表明，对原位DNA变性更敏感的精子细胞可能具有更多可及的内源性DNA链断裂。我们推测，在从体细胞组蛋白复合物向鱼精蛋白复合物的正常转变过程中产生的DNA链断裂未得到正确连接，从而导致残留的DNA链断裂和染色质结构改变。或者，改变的染色质结构可能导致内源性DNA链断裂的可及性。
