Molecular population-genetic studies on the adaptation of Drosophila.

(1)在限制性内切酶图谱比较的基础上，比较了北方和南方黑腹果蝇种群生存能力的遗传变异。虽然两个群体的加性遗传方差有很大差异，但核子多样性没有检测到差异。这可能表明，北方和南方群体之间的差异只是由于有限的座位数量。(2)我们设计了一种利用多态倒置在DNA水平上寻找有益突变的方法。使用这项技术，我们调查了美国和日本的几个自然种群。以含ADH基因的DNA片段(约10kb)为探针。到目前为止，已经检测到了一个有益突变的候选基因。这是位于ADH编码区3‘侧的约3kb的插入。(3)利用第二染色体上的自发突变和已有突变，检测X连锁结构基因的活性是否被这些突变，特别是位于其他染色体上的多基因突变所改变，并得到阳性结果。(4)我们已经报道了淀粉酶的诱导性与适合度之间存在正相关，并正在尝试在DNA水平上获得其基础。(5)通过对1970年采集的种群和自然种群采集的蝇类的比较，研究了种群入侵后P元素的动态变化。采用原位杂交技术、无菌试验和遗传负荷等方法。

The following 5 experiments were conducted;(1)On the basis of restriction map comparison, genetic variability with respect to viability was compared between noethern and southern populations of Drosophila melanogaster. Although there is much difference in additive genetic variance between the two populations the difference in nucleon diversity could not be detected. This may indicate that the difference between the northern and southern populations is due to only limited number of loci.(2) We have devised a method using polymorphic inversions to search beneficial mutations at the DNA level. Using this technique we surveyed several natural populations of D.melanogaster both in the U.S.A. and Japan. As the probe DNA segmeut (about 10Kb) including the ADH locus was employed. Until now, one candidate of the beneficial mutation has been detected. This is an insertion of about 3Kb that is located in the 3' side of the ADH coding region. (3) Using the spontaneous and existing mutations in the second chromosomes, it was examined whether or not the activity of the X-linked structural genes is modified by the mutations, especially polygenic mutations that are located in the other chromosomes, and the positive result was obtained. (4) We have already reported that there is a positive correlation between inducibility of amylase and fitness and an attempt to obtain its basis at the DNA level is going on. (5) Dynamics of the P elements after invasion to a population was investigated by comparing the stock sampled in 1970 and flies sampled from natural populations. In situ hybridization technique, sterility test and the genetic load were employed.