Rao P N, Wilson B, Puck T T
J Cell Physiol. 1977 Apr;91(1):131-41. doi: 10.1002/jcp.1040910113.
The application of the phenomenon of premature chromosome condensation for cell cycle analysis in HeLa and CHO cells has been examined. Random populations of HeLa and CHO cells pulse labelled with H3-TdR were separately fused with mitotic HeLa cells using U.V. inactivated Sendai virus. The resulting prematurely condensed chromosomes (PCC) were scored and classified into G1, S and G2-PCC on the basis of both morphological and autoradiographic data, The results of this study indicated that the G1, S and G2 phase cells are equally susceptible to virus-induced fusion with mitotic cells and subsequent induction into PCC. Hence the PCC method for cell cycle analysis is both practical and accurate. This study also revealed that the process of chromosome decondensation initiated during the telophase of mitosis continues throughout the G1 period reaching an ultimate state of decondensation by the end of G1, at which point the fusion of such cells with those in mitosis yield PCC with the most diffused morphology instead of the discrete single stranded structures characteristic of early G1-PCC. Thus, the decondensation of chromatin during G1 appears to be a prerequisite for the subsequent initiation of DNA synthesis.
已对早熟染色体凝聚现象在HeLa细胞和CHO细胞的细胞周期分析中的应用进行了研究。用H3-TdR脉冲标记的HeLa细胞和CHO细胞的随机群体，分别使用紫外线灭活的仙台病毒与有丝分裂期的HeLa细胞融合。根据形态学和放射自显影数据，对产生的早熟凝聚染色体（PCC）进行评分并分类为G1期、S期和G2期PCC。本研究结果表明，G1期、S期和G2期细胞同样容易受到病毒诱导与有丝分裂细胞融合并随后诱导形成PCC。因此，用于细胞周期分析的PCC方法既实用又准确。本研究还揭示，在有丝分裂末期开始的染色体解凝聚过程在整个G1期持续进行，到G1期末达到最终的解凝聚状态，此时这些细胞与有丝分裂期细胞融合会产生形态最分散的PCC，而不是早期G1期PCC特有的离散单链结构。因此，G1期染色质的解凝聚似乎是随后启动DNA合成的先决条件。
