The difference between spontaneous and base-analogue induced mutations of phage T4
The difference between spontaneous and base-analogue induced mutations of phage T4
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DOI：
10.1073/pnas.45.4.622
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发表时间：
1959-01-01
期刊：
影响因子：
--
通讯作者：
FREESE, E.
中科院分区：
文献类型：
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作者：
FREESE, E.
液体介质中的还原速率。将rII型突变体的菌落接种于细菌K上，可以选择性地检测到rII型突变体的回复突变体。在大多数情况下，斑块是野生型的，例外情况将在后面讨论。为了定量测定回复突变率，最好从给定数量的少量接种物（例如，100 μ l）制备裂解物。与平行培养物相比，先前储备液中已存在的回复突变体的引入则很少见，并且可以通过裂解物中异常大比例的回复突变体容易地检测到。回复突变体比例的波动也是因为相应的突变可能发生在噬菌体生长的早期或晚期，回复突变体在形成后可以繁殖。这种异常大的波动被称为”头奖“。“对于从100 μ l接种物生长的原种，回复体与活菌的平均比率（在B上测定）称为回复指数。
RESULTSReversion Rates in Liquid Medium.-Revertants of rII-type mutants can be detected, selectively, when the phages of an rII-type stock are plated on bacteria K. In most cases plaques are of the wild phenotype; exceptionswill be discussed later. For a quantitative measurement of reversion rates, it is best to prepare Iysates from a small inoculum of given number (eg, 100 phages). The introduction of a revertant, already present in the previous stock, is then rare, and can easily be detected by an exceptionally large proportion of revertants in the lysate, when compared to parallel cultures. Fluctuations in the proportion of revertants also arise because the corresponding mutations may occur early or late in phagegrowth, and the revertants can multiply after their formation. An unusually great fluctuation of this kind will be called a" jackpot." Theaverage ratio of revertantsto viable phages (assayed on B), for stocks grown from an inoculum of 100 phages, is called the reversion index.