REPLICATION, DIVISION AND MECHANISMS CONTROLLING THE VARIABLE DNA CONTENT IN THE HETEROMERIC MACRONUCLEUS OF CHILODONELLA-STEINI (CILIATA)
REPLICATION, DIVISION AND MECHANISMS CONTROLLING THE VARIABLE DNA CONTENT IN THE HETEROMERIC MACRONUCLEUS OF CHILODONELLA-STEINI (CILIATA)
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DOI：
10.1016/s0003-9365(85)80050-6
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发表时间：
1985-01-01
期刊：
影响因子：
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通讯作者：
RADZIKOWSKI, S
中科院分区：
文献类型：
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作者：
RADZIKOWSKI, S
在斯氏奇齿藻的大核中，可以区分出以下区域：1）内区（参数），染色质呈纤维状超微结构，电子密度中等，含有一个位于中心的电子致密物质簇形式的内体; 2）外区（正着丝粒），染色质呈不同大小的电子致密颗粒形式，核仁众多。发现DNA复制有两个阶段，第一阶段在副节开始，第二阶段在正节开始。在副节DNA复制结束后，正节DNA复制继续进行。在一个世代中，一部分用3-H-TdR（3 H-Thymine-deoxyribose）标记的DNA在下一代的正向节和内体中被发现，而在正向节中标记的DNA保留在其复制的地方，而不与副节的DNA混合。然而，其中一些DNA移动到内体。在平均世代时间为12 h的情况下，周期的不同阶段的持续时间如下：对于大核，G1 = 5.5 h，S = 5.5 h，G2 = 1 h，M = 0.5 h;对于微核，G1 = 1 h，S = 1 h，G2 = 10 h，M = 0.5 h。结果发现，姐妹大核的DNA含量的差异是由于不平等的分裂的正节的DNA，也是正节的DNA是受到相当大的数量波动取决于文化的状态，不像副节的DNA。本文讨论了直粒中DNA的性质，认为它是rDNA。
In the macronucleus of Chilodonella steini the following regions can be distinguished: 1) the inner zone (parameter) with chromatin exhibiting a fibrillar ultrastructure and medium electron-density, containing a centrally located endosome in the form of a cluster of electron-dense material, and 2) the outer zone (orthomere) with chromatin in the form of electron-dense granules of different size and numerous nucleoli. It was found that there are two stages of DNA replication, the first beginning in the paramere and the second in the orthomere. DNA replication of the orthomere is continued after DNA replication of paramere has ended. A part of the DNA labelled with 3-H-TdR (3H-Thymine-deoxyribose) in one generation in the paramere is found in the orthomere and endosome in the subsequent generation, while DNA labelled in the orthomere remains at the place of its replication without mixing with DNA of the paramere. Some of this DNA, however, moves to the endosome. With an average generation time of 12 h the duration of the different phases of the cycle is as follows: for the macronucleus, G1 = 5.5 h, S = 5.5 h, G2 = 1 h, M = 0.5 h, and for micronucleus, G1 = 1 h, S = 1 h, G2 = 10 h, M = 0.5 h. It was found that differences in DNA contents of sister macronuclei are due to unequal division of the DNA of the orthomere, and also that the DNA of the orthomere is subject to considerable quantitative fluctuation depending on the state of the culture, unlike the DNA of the paramere. The nature of DNA occurring in the orthomere is discussed, and it appears to be rDNA.