Cyclic X-Ray Responses in Mammalian Cells in Vitro1
Cyclic X-Ray Responses in Mammalian Cells in Vitro1
复制标题
体外哺乳动物细胞的循环 X 射线反应1
DOI：
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发表时间：
1968
期刊：
影响因子：
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通讯作者：
W. K. Sinclair
中科院分区：
文献类型：
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作者：
W. K. Sinclair
哺乳动物细胞的各种辐射反应取决于照射时细胞在其世代周期内的位置(即其年龄)。研究通常是通过照射体外同步的细胞群体来进行的。不同细胞系的结果不容易比较，但这里试图指出细胞杀伤和分裂延迟方面的异同。总的来说，到目前为止获得的存活数据表明，在G1期较短的细胞中，有丝分裂最敏感，G2期最敏感，G1期不太敏感，在S时期的后期最不敏感。在具有长G1期的细胞中，除了上述情况外，通常在G1期早期有一个抵抗期，然后在其末期附近有一个敏感期。(后者可能和有丝分裂一样敏感。)已注意到上述情况的例外情况，特别是在一些L细胞亚系中，并给出了可能的解释。在中国仓鼠细胞中，照射后的最大存活时间出现在S时期，但与DNA合成最大速率的时间或DNA合成的最大细胞数的时间不一致，而且抑制合成DNA的细胞也会发生存活率的变化。相反，生存取决于细胞在当时的周期中所处的位置，这不仅涉及DNA合成，还涉及其他过程。存活率与DNA合成并不完全相关，因为在照射之前或之后停止DNA合成对存活率的影响最大只是轻微的。分裂延迟表现出与大多数细胞系相似的响应模式。有丝分裂中的细胞受照射后延迟较大，G1期细胞延迟较小，S期间细胞延迟最大，G2期细胞延迟较小。L细胞或人肾细胞在G2期照射后的分裂延迟时间可能长于S期照射的细胞。这一结果可以用分裂延迟的二分量模型来解释。一种是由于DNA合成速度减慢导致S周期延长，另一种是G2期的阻滞，与DNA合成无关。这两种成分的比例在不同的细胞系中可能会有所不同。
Various radiation responses in mammalian cells depend on the position of the cell within its generation cycle (that is, its age) at the time of irradiation. Studies have most often been made by irradiating synchronized populations of cells in vitro. Results in different cell lines are not easy to compare, but an attempt has been made here to point out similarities and differences with regard to cell killing and division delay. In general, survival data obtained so far show that, in cells with a short G1, cells are most sensitive in mitosis and in G2, less sensitive in G1, and least sensitive during the latter part of the S period. In cells with a long G1, in addition to the above, there is usually a resistant phase early in G1 followed by a sensitive stage near its end. (The latter may be as sensitive as mitosis.) Exceptions to the above, especially in some L cell sublines, have been noted, and a possible explanation is given. In Chinese hamster cells, maximum survival after irradiation occurs during S, but it does not coincide with the time of the maximum rate of DNA synthesis or with the time of the maximum number of cells in DNA synthesis, and changes in survival also occur in cells inhibited from synthesizing DNA. Rather, survival depends on the position the cell has reached in the cycle at that time, which involves not only DNA synthesis but other processes as well. Survival is not completely correlated with DNA synthesis, since halting DNA synthesis just before or just after irradiation only slightly affects survival at its maximum. Division delay exhibits a pattern of response which is similar in most cell lines. Delay is considerable for cells irradiated in mitosis, is small for cells in G1, increases to a maximum for cells during S, and declines for cells in G2. L cells or human kidney cells may have a longer delay for cells irradiated in G2 than for those irradiated in S. The results can be explained in terms of a two-component model of division delay. One component results from the prolongation of the S period due to the reduced rate of DNA synthesis, and the other, a block in G2, is independent of DNA synthesis. The proportion of the two components may vary in different cell lines.