TRANSITION OF STARVING DICTYOSTELIUM CELLS TO DIFFERENTIATION PHASE AT A PARTICULAR POSITION OF THE CELL-CYCLE
TRANSITION OF STARVING DICTYOSTELIUM CELLS TO DIFFERENTIATION PHASE AT A PARTICULAR POSITION OF THE CELL-CYCLE
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DOI：
10.1111/j.1432-0436.1989.tb00744.x
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发表时间：
1989-09-01
期刊：
影响因子：
2.9
通讯作者：
AMAGAI, A
中科院分区：
文献类型：
--
作者：
MAEDA, Y;OHMORI, T;AMAGAI, A
参考饥饿开始时的细胞周期位置，使用通过温度变化（11.5 ℃）同步化的细胞，分析盘基网柄藻Ax-2中增殖和分化之间的关系。C-22.0.degree. C）。为了研究在细胞周期的任何特定阶段的Ax-2细胞能够在营养缺乏的情况下通过周期进展多远，我们测量了饥饿后细胞数量和核性的时间变化。在同步发育的细胞核DNA合成也监测脉冲标记与[甲基-3H]胸苷。细胞数目的增加和随后的DNA合成发生在刚好在有丝分裂之前的细胞中（称为T0.5细胞和T1细胞;从11.5 ℃向上移动后0.5小时和1小时）。C至22.0 °。C），但在T3、T5或T7细胞中不存在。当T1细胞在缺乏外部营养物的情况下孵育6小时时，它们（T1+6细胞）表现出与T7细胞相似的发育特征，其在饥饿后最快地获得对3 ''，5 ''-环磷酸腺苷（cAMP）的趋化敏感性和抗EDTA的凝聚性。因此，很可能Ax-2细胞可以通过细胞周期进展到特定点（可能是T7细胞的细胞周期位置），而不管营养物的存在或不存在，并且在营养缺乏的条件下从该点进入分化期。有没有差异的比例prestalk prepore细胞在迁移性假原质团来源于细胞已在其他细胞周期的位置饥饿。细胞周期依赖的变化在分化的时间可能的意义进行了讨论，在有关模式的形成和细胞类型的比例。
The relationship between proliferation and differentiation in Dictyostelium discoideum Ax-2 was analyzed with reference to the cell-cycle position at the onset of starvation, using cells synchronized by temperature shift (11.5.degree. C-22.0.degree. C). To examine how far Ax-2 cells at any particular phase of the cell cycle are able to progress through the cycle in response to nutritional deprivation, we measured temporal changes in cell number and nuclearity after starvation. Nuclear DNA synthesis in synchronously developing cells was also monitored by pulse-labeling with [methyl-3H]thymidine. Increase in cell number and subsequent DNA synthesis occurred in cells just before mitosis (referred to as T0.5 cells and T1 cells; 0.5 h and 1 h after the shift-up from 11.5.degree. C to 22.0.degree. C respectively), but not in T3, T5, or T7 cells. When T1 cells were incubated for 6 h in the absence of external nutrients, they (T1+6 cells) exhibited developmental features similar to T7 cells, which most rapidly acquired chemotactic sensitivity to 3'',5''-cyclic adenosine monophosphate (cAMP) and EDTA-resistant cohesiveness after starvation. Thus, it is quite likely that Ax-2 cells may progress through the cell cycle to a particular point (possibly the cell-cycle position of T7 cells), irrespective of the presence or absence of nutrients, and enter the differentiation phase from this point under conditions of nutritional deprivation. There was no difference in the ratio of prestalk to prespore cells in migratory pseudoplasmodia derived from cells that had been starved at other cell-cycle positions. The possible significance of cell-cycle-dependent variations in the timing of differentiation is discussed in relation to pattern formation and cell-type proportioning.