Gatti M, Pimpinelli S, De Marco A, Tanzarella C
Mutat Res. 1975 Dec;33(2-3):201-12. doi: 10.1016/0027-5107(75)90196-7.
Third instar larvae of the Oregon R stock were treated for 25 or 30 min with vapour of methyl methanesulphonate (MMS). At various times after the treatment (4, 8 and 12 h), microscope specimens of the nerve ganglia were prepared. At all the times of fixation, only aberrations of a chromatid type were found, but with different frequencies in the two sexes. The females were about 3 times more sensitive than the males to MMS. An analysis of the distribution of the breaks between and within chromosomes showed that they were not localized at random but were clustered in the heterochromatic centromere regions of the X chromosome and the autosomes. The Y chromosome, although entirely heterochromatic, on the other hand, was highly resistant to MMS. However, this phenomenon had only a very weak effect upon the variation with sex of MMS-induced chromosome damage. Among the aberrations induced, although interchanges were normally present, neither intra-exchanges nor triradials were found. In the interchanges, there was a greater tendency for the homologous chromosomes to be involved, and these rejoined symmetrically. The above results are discussed in relation to data previously obtained with X-rays.
用甲磺酸甲酯（MMS）蒸汽处理俄勒冈R品系的三龄幼虫25或30分钟。在处理后的不同时间点（4、8和12小时），制备神经节的显微镜标本。在所有固定时间，仅发现染色单体型畸变，但两性中的频率不同。雌性对MMS的敏感性比雄性高约3倍。对染色体间和染色体内断裂分布的分析表明，它们并非随机定位，而是聚集在X染色体和常染色体的异染色质着丝粒区域。另一方面，Y染色体虽然完全是异染色质，但对MMS具有高度抗性。然而，这种现象对MMS诱导的染色体损伤的性别差异影响非常小。在诱导的畸变中，虽然通常存在互换，但未发现染色体内互换或三射体。在互换中，同源染色体更倾向于参与，并且它们对称地重新连接。结合先前用X射线获得的数据对上述结果进行了讨论。
