Floros J, Chang H, Baserga R
Science. 1978 Aug 18;201(4356):651-2. doi: 10.1126/science.675253.
Cytoplasmic extracts of proliferating cells stimulate DNA synthesis in isolated nuclei of Xenopus laevis liver. When tested by the same assay, cytoplasmic extracts of resting cells are completely inactive. When cytoplasmic extracts are prepared from cell cycle-specific temperature-sensitive mutants arrestd in the G1 phase of the cell cycle by the nonpermissive temperature, they also fail to stimulate DNA synthesis in frog nuclei. The results indicate that, to stimulate DNA synthesis in isolated frog nuclei, essentially all information of G1 cells must be present.
增殖细胞的细胞质提取物能刺激非洲爪蟾肝脏分离细胞核中的DNA合成。用相同的检测方法进行测试时，静止细胞的细胞质提取物则完全没有活性。当从细胞周期特异性温度敏感突变体中制备细胞质提取物时，这些突变体在非允许温度下停滞在细胞周期的G1期，它们也无法刺激蛙细胞核中的DNA合成。结果表明，要刺激分离的蛙细胞核中的DNA合成，G1期细胞的基本所有信息都必须存在。
