Division of Cell Medicine, Research Institute of Medical Science, Kanazawa Medical University, Uchinada, Ishikawa, 920-0293, Japan.
Hum Cell. 2011 Jun;24(2):78-85. doi: 10.1007/s13577-011-0017-0. Epub 2011 May 15.
Haploid unit-ploidy transition in tetraploid and octaploid mouse H1 (ES) cells (4H1 and 8H1 cells, respectively) during long-term culturing was observed using flow cytometry. The DNA content of 4H1 cells was elevated from 3.5C to 4.5C, and that of 8H1 cells was degraded from 6.5C to 5.5C, in addition to gradual DNA loss (C: complement). The timing of the transition was not predetermined. Cell cycle parameters, doubling time and phase durations, were essentially the same before and after the transition, suggesting that most cells in a cell population were induced to undergo the ploidy transition at the same time. Cellular morphology was altered before and after the transition, suggesting that the ploidy shift changed cellular characteristics; however, pluripotency was maintained irrespective of DNA content. Cell volume correlated with DNA content during the final stage of culturing. Diploid and hexaploid H1 (ES) cells--2H1 and 6H1 cells, respectively--were used as control cells in which the ploidy was maintained for about 300 days of culturing. The haploid unit-ploidy transition was explained using a hypothesis concerning the DNA structure of polyploid cells: closing homologous chromosomes causes inhomogeneous cell division accompanying a haploid DNA set, suggesting the existence of a coupling apparatus connecting DNA fibers with a single haploid DNA set.
通过流式细胞术观察到，在长期培养过程中，四倍体和八倍体小鼠 H1（ES）细胞（分别为 4H1 和 8H1 细胞）中的单倍体单元倍性转变。4H1 细胞的 DNA 含量从 3.5C 升高到 4.5C，8H1 细胞的 DNA 含量从 6.5C 降低到 5.5C，此外还伴有逐渐的 DNA 丢失（C：补体）。转变的时间不是预先确定的。细胞周期参数、倍增时间和相位持续时间在转变前后基本相同，表明细胞群体中的大多数细胞同时被诱导进行倍性转变。转变前后细胞形态发生改变，表明倍性转移改变了细胞特征；然而，无论 DNA 含量如何，多能性都得以维持。细胞体积在培养的最后阶段与 DNA 含量相关。二倍体和六倍体 H1（ES）细胞——分别为 2H1 和 6H1 细胞——被用作控制细胞，其倍性在大约 300 天的培养中得以维持。通过一个关于多倍体细胞 DNA 结构的假设来解释单倍体单元倍性转变：关闭同源染色体导致伴随单倍体 DNA 集的不均匀细胞分裂，这表明存在一个连接 DNA 纤维与单个单倍体 DNA 集的耦合装置。
