Cordelli E, Fresegna A M, Leter G, Eleuteri P, Spanò M, Villani P
Section of Toxicology and Biomedical Sciences-ENEA CR Casaccia, Rome, Italy.
Radiat Res. 2003 Oct;160(4):443-51. doi: 10.1667/rr3053.
To evaluate whether DNA alterations in mature spermatozoa could stem from DNA damage induced in immature germ cells, testis cells and spermatozoa were analyzed by the comet assay and by the sperm chromatin structure assay 14, 45 and 100 days after in vivo X irradiation of the testes. These times were selected, according to the mouse seminiferous epithelium cycle, to follow the DNA damage induced in different germ cell compartments. The cytotoxic action was assessed by DNA flow cytometric analysis of testicular cells. A dose-dependent increase of DNA damage in testis cells was observed 14 days after irradiation, whereas mature sperm cells were not affected. On the other hand, an increase in DNA strand breaks was seen in spermatozoa 45 days after treatment. DNA damage returned to the control levels 100 days after irradiation. The methods used to evaluate DNA damage gave comparable results, emphasizing the correlation between DNA fragmentation and susceptibility of sperm chromatin to denaturation. Both techniques showed the high radiosensitivity of differentiating spermatogonia. The overall results showed that DNA damage induced in pre-meiotic germ cells is detectable in primary spermatocytes and is still present in mature spermatozoa.
为了评估成熟精子中的DNA改变是否源于未成熟生殖细胞中诱导的DNA损伤，在对睾丸进行体内X射线照射后的14、45和100天，通过彗星试验和精子染色质结构分析对睾丸细胞和精子进行了分析。根据小鼠生精上皮周期选择这些时间，以追踪不同生殖细胞区室中诱导的DNA损伤。通过对睾丸细胞进行DNA流式细胞术分析来评估细胞毒性作用。照射后14天观察到睾丸细胞中DNA损伤呈剂量依赖性增加，而成熟精子细胞未受影响。另一方面，处理后45天精子中可见DNA链断裂增加。照射后100天，DNA损伤恢复到对照水平。用于评估DNA损伤的方法给出了可比的结果，强调了DNA片段化与精子染色质对变性的敏感性之间的相关性。两种技术均显示分化型精原细胞具有高放射敏感性。总体结果表明，减数分裂前生殖细胞中诱导的DNA损伤在初级精母细胞中可检测到，并且在成熟精子中仍然存在。
