BACTERIAL CHROMOSOME AND ITS MANNER OF REPLICATION AS SEEN BY AUTORADIOGRAPHY
BACTERIAL CHROMOSOME AND ITS MANNER OF REPLICATION AS SEEN BY AUTORADIOGRAPHY
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DOI：
10.1016/s0022-2836(63)80070-4
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发表时间：
1963-01-01
影响因子：
5.6
通讯作者：
SINSHEIMER, RL
中科院分区：
文献类型：
--
作者：
CAIRNS, J;SINSHEIMER, RL
为了确定复制DNA的形式，用[H3]胸腺嘧啶核苷标记了不同时期的大肠杆菌B3和K12HFR。然后轻轻提取他们的DNA，并通过放射自显影进行观察。研究结果和结论可概括如下。(1)大肠杆菌的染色体由一段双链DNA组成，长700到900 u。(2)这种DNA通过形成叉子进行复制。叉子的新(女)枝各包含一股新材料和一股旧材料。(3)DNA的每条染色体长度可能由一个叉子复制。因此，当细菌产生时间为30min时，每分钟复制20至30u的DNA。(4)完全出乎意料的是，发现两个子体分子的远端似乎在复制期间连接在一起。这其中的原因并不清楚。可以想象，在体内缠绕子体分子的机制在于它们的连接点，而不是通常认为的叉子本身。(5)B3(F-)和K12(HFR)的染色体均呈圆形，在提取过程中常断裂。
In order to determine the form of replicating DNA, E. coli B3 and K12 Hfr were labelled for various periods with [H3]thymidine. Their DNA was then extracted gently and observed by autoradiography. The results and conclusions can be summarized as follows. (1) The chromosome of E. coli consists of a single piece of two-stranded DNA, 700 to 900 u long. (2) This DNA duplicates by forming a fork. The new (daughter) limbs of the fork each contain one strand of new material and one strand of old material. (3) Each chromosome length of DNA is probably duplicated by one fork. Thus, when he bacterial generation time is 30 min, 20 to 30 u of DNA is duplicated each minute. (4) Totally unexpected was the finding that the distal ends of the two daughter molecules appear to be joined during the period of replication. The reason for this is obscure. Conceivably the mechanism that, in vivo, winds the daughter molecules lies at the point of their union rather than, as commonly supposed, in the fork itself. (5) The chromosomes of both B3 (F-) and K12 (Hfr) appear to exist as a circle which usually breaks during extraction.