Ishii Y, Watatani M
Basic Life Sci. 1984;29 Pt A:173-80. doi: 10.1007/978-1-4684-4889-4_14.
Sister chromatid exchanges (SCEs) and homologous chromatid exchanges (chromatid exchanges between homologous chromosomes at homologous sites) are similar, not only in the type of chromosomal alteration but also in their high yields in Bloom syndrome cells or in cells treated with mitomycin C (MMC). However, the similarity between SCEs and homologous exchanges seems superficial as evidenced by the present experiments. In human lymphocytes, when caffeine was added during the S phase under conditions of concurrent exposure to MMC, both SCEs and homologous exchanges increased. However, when caffeine was added during the G2 phase, the frequency of SCEs remained unaffected whereas the frequency of homologous and nonhomologous chromatid exchanges decreased and that of other types of chromatid aberrations increased. We conclude that the process of formation of SCEs is, at least partly, different from that of chromatid exchanges or other types of chromatid aberrations, the former presumably occurring during the S phase and the latter during the G2 phase.
姐妹染色单体交换（SCEs）和同源染色单体交换（同源染色体在同源位点之间的染色单体交换）很相似，不仅在染色体改变类型方面，而且在布卢姆综合征细胞或用丝裂霉素C（MMC）处理的细胞中它们的高发生率方面。然而，正如目前实验所证明的，SCEs和同源交换之间的相似性似乎只是表面的。在人淋巴细胞中，当在S期同时暴露于MMC的条件下添加咖啡因时，SCEs和同源交换都增加。然而，当在G2期添加咖啡因时，SCEs的频率保持不变，而同源和非同源染色单体交换的频率降低，其他类型的染色单体畸变的频率增加。我们得出结论，SCEs的形成过程至少部分不同于染色单体交换或其他类型的染色单体畸变的形成过程，前者大概发生在S期，而后者发生在G2期。
