Tomilin N, Solovjeva L, Krutilina R, Chamberland C, Hancock R, Vig B
Institute of Cytology, Russian Academy of Sciences, St Petersburg.
Chromosome Res. 1995 Jan;3(1):32-40. doi: 10.1007/BF00711159.
Newly synthesized DNA in mammalian nuclei is concentrated in discrete nuclear granules called replication foci. These foci may be visualized using antibodies against 5-bromodeoxyuridine. In the early S-phase cells 100-250 foci are usually detected. On average, individual foci range between 0.5 and 2 microns in diameter and can be seen as clusters of more than ten average-sized (60-100 kb) synchronously activated replicons. In this study, employing minor modifications of the previous methods, we report the visualization of small replication foci of about 0.3 micron diameter (mini-foci). Some foci are clustered into folded chains consisting of 2-40 subunits. DNA content of one mini-focus is estimated to be 50-120 kb and there are 500-1500 mini-foci per cell in the early S-phase. Experimentally induced decrease in replicon size does not affect the size of mini-foci, suggesting that these represent elementary units of DNA replication in mammalian nuclei and are probably identical to the basic structural DNA loop domains.
哺乳动物细胞核中新合成的DNA集中在称为复制灶的离散核颗粒中。这些复制灶可以使用抗5-溴脱氧尿苷的抗体进行可视化观察。在S期早期细胞中，通常可检测到100 - 250个复制灶。平均而言，单个复制灶的直径在0.5至2微米之间，可被视为由十多个平均大小（60 - 100 kb）的同步激活的复制子组成的簇。在本研究中，我们对先前的方法进行了微小修改，报告了直径约0.3微米的小复制灶（微型灶）的可视化观察。一些复制灶聚集成由2 - 40个亚基组成的折叠链。一个微型灶的DNA含量估计为50 - 120 kb，在S期早期每个细胞中有500 - 1500个微型灶。实验诱导的复制子大小减小并不影响微型灶的大小，这表明这些微型灶代表了哺乳动物细胞核中DNA复制的基本单位，并且可能与基本的结构性DNA环结构域相同。
