Hameister H, Sperling K
Chromosoma. 1984;90(5):389-93. doi: 10.1007/BF00294166.
Mammalian chromosome replication was studied by the aid of premature chromosome condensation (PCC). After induction of PCC the sites of DNA replication appear as "gaps" between condensed chromosomal regions. These condensed particles are unineme before and bineme after DNA replication. The two phases are due mainly to the unineme or bineme nature of the particles. During early S-phase almost all particles are unimene, during late S-phase they are bineme and there is only one transitory stage between these two main stages. Premature chromosome condensation was studied in detail on a specific human chromosome 22 which is marked by its heterochromatin constitution. This led to easy identification of these elements in S-phase PCC (S-PCC) preparations. For each stage of the S-phase there was a reproducible pattern of condensed chromosomal particles making up the whole chromosome. The number of these particles was rather limited and a complementary pattern was found in early versus late S-phase. The pattern of early S-PCC corresponded to the banding pattern of G-banded prometaphase chromosomes; the pattern of late S-PCC, to R-banded prometaphase chromosomes. Thus, "gaps" and condensed particles as observed after PCC induction are obviously homologous to chromosome replication units. Replication of constitutive heterochromatin occurred during the very late S-phase. During this stage PCC induction led to condensation of the heterochromatin into several small, highly fluorescent particles.
借助早熟染色体凝聚（PCC）对哺乳动物染色体复制进行了研究。诱导PCC后，DNA复制位点表现为凝聚染色体区域之间的“间隙”。这些凝聚颗粒在DNA复制前是单线状，复制后是双线状。这两个阶段主要归因于颗粒的单线状或双线状性质。在S期早期，几乎所有颗粒都是单线状，在S期后期它们是双线状，并且在这两个主要阶段之间只有一个过渡阶段。在一条特定的人类22号染色体上对早熟染色体凝聚进行了详细研究，该染色体以其异染色质结构为特征。这使得在S期PCC（S-PCC）制备物中易于识别这些元件。对于S期的每个阶段，都有组成整条染色体的凝聚染色体颗粒的可重复模式。这些颗粒的数量相当有限，并且在S期早期和晚期发现了互补模式。早期S-PCC的模式与G带中期染色体的带型相对应；晚期S-PCC的模式与R带中期染色体的带型相对应。因此，PCC诱导后观察到的“间隙”和凝聚颗粒显然与染色体复制单位同源。组成型异染色质的复制发生在S期的很晚阶段。在此阶段，PCC诱导导致异染色质凝聚成几个小的、高荧光颗粒。
