PCR ANALYSIS OF STARVATION INDUCED DNA REARRANGEMENTS

现在被广泛接受的是，通过选择，压力条件会导致突变频率的增加。现在由“定向突变”问题提出的问题是，由特定的应激机制引起的变化的特殊性。为了回答这个问题，有必要描述所有DNA变化的特征，无论它们是否在选择性条件下促进生长。现在，这可以通过聚合酶链式反应技术来完成。聚合酶链式反应使得在压力后检测基因组的特定区域和检测新的DNA结构成为可能，即使它们不能通过生长来选择。初步结果表明，在正常生长条件下，由Mu噬菌体转座元件介导的一类特定的DNA重排不会发生，但在选择的条件下，很容易在相对较高的频率下检测到。使用聚合酶链式反应现在可以检测这种基因重排发生的频率和时间，无论有没有选择性技术，这通常是测量突变率所需的。

It is now widely accepted that stress conditions lead to an increase in the frequencies of mutation measured by selection. The question now raised by the "Directed mutation" issue is the specificity of the changes induced by particular stress regimes. To answer this question, it is necessary to characterize all DNA changes regardless of whether they facilitate growth under selective conditions. This can now be done by PCR technology. PCR makes it possible to examine specific regions of the genome following stress and detect novel DNA structures, even if they can not be selected by growth. Initial results demonstrated that a specific class of DNA rearrangement mediated by the Mu phage transposable element did not measurably occur under normal growth conditions but were easily detectable at relatively high frequencies under selective conditions. Use of PCR will now allow detection of the frequency and time of occurance of such genetic rearrangements with and without the selective techniques that are usually required for measuring mutation rates.