Asynchronous duplication of chromosomes in cultured cells of Chinese hamster.
Asynchronous duplication of chromosomes in cultured cells of Chinese hamster.
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中国仓鼠培养细胞中染色体的异步重复。
DOI：
10.1083/jcb.7.3.455
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发表时间：
1960-06
期刊：
影响因子：
--
通讯作者：
TAYLOR, J H
中科院分区：
文献类型：
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作者：
TAYLOR, J H
本文用胸腺嘧啶核苷-H_3掺入放射自显影法研究了中国仓鼠培养细胞的染色体复制（DNA合成）。所使用的技术是将快速生长的细胞的异步分裂群体暴露于具有胸苷-H3的培养基10分钟间隔。然后将细胞转移至含有过量未标记胸苷的培养基中。在此之后的时间间隔和标记的间期和分裂图的频率，以及特定染色体的标记模式进行了采样和研究。在这些实验期间的平均生成时间为约14小时。DNA合成发生在约6小时的间隔期间，并在中期前2至3小时停止。中期分裂后，染色体通常在5 - 6小时内开始重复。颗粒计数，以估计与胸苷-H3短暂接触后，并在转移到过量的未标记的胸苷的培养基后的时间间隔，氚掺入的量，表明标记的前体的细胞内池在不到一分钟内稀释，使进一步的标记将不会被检测到。在接触期间标记的染色体通过另一个重复周期保留其精确的标记模式，并且没有检测到DNA的周转或氚的损失。补体的5或6条染色体具有通常在复制后期的片段。其中两个是X和Y染色体。X染色体的长臂和整个Y染色体在DNA合成间隔的后半部分进行复制。雄性品系中X染色体的短臂在前半个间隔中重复。在另一个品系（雌性）中，一条X染色体具有相同的时间，但另一条X染色体在DNA合成期的后半期全部复制。2条中等大小染色体短臂上的DNA以及补体中1条或2条最小染色体上的大部分DNA复制较晚。这项研究导致了一种假设，即不同的染色体或染色体的一部分在复制中具有遗传控制的序列，这可能具有某些功能意义。
Chromosome duplication (DNA synthesis) was studied in cultured cells of Chinese hamsters by means of autoradiography following thymidine-H3 incorporation. The technique used was to expose an asynchronously dividing population of rapidly growing cells for a 10 minute interval to a medium with thymidine-H3. Cells were then transferred to a medium with excess unlabeled thymidine. The population was sampled at intervals thereafter and studies made of the frequency of labeled interphases and division figures, and the patterns of labeling of specific chromosomes. The average generation time during these experiments was about 14 hours. DNA synthesis occurred during an interval of about 6 hours and stopped 2 to 3 hours before metaphase. After metaphase the chromosomes usually begin duplication again within 5 to 6 hours. Grain counting, to estimate the amount of tritium incorporated after a short contact with thymidine-H3 and at intervals after transfer to a medium with excess unlabeled thymidine, indicated that the intracellular pool of labeled precursors was diluted within less than a minute so that further labeling would not be detected. The chromosomes labeled during the contact period retained their precise pattern of labeling through another duplication cycle and no turnover of DNA or loss of tritium was detectable. Five or 6 chromosomes of the complement have segments typically late in duplication. Two of these are the X and Y chromosomes. The long arm of the X chromosome and the whole Y chromosome are duplicated in the last half of the interval of DNA synthesis. The short arm of the X chromosome in a male strain is duplicated in the first half of the interval. In another strain (female), one X chromosome had the same timing, but the other one was all duplicated in the last half of the period of DNA synthesis. The DNA in the short arms of 2 medium sized chromosomes, as well as most of the DNA in 1 or 2 of the smallest chromosomes of the complement was replicated late. The study has led to the hypothesis that various chromosomes or parts of chromosomes have a genetically controlled sequence in duplication which may have some functional significance.