Molecular population-genetic studies on the adaptation of Drosophila.

进行了以下5个实验：（1）在限制性酶切图谱比较的基础上，比较了黑腹果蝇（Drosophilamelanogaster）的noeclampus和southern种群在生活力方面的遗传变异。虽然两个群体的加性遗传方差有很大差异，但核子多样性差异不明显。这可能表明，北方和南方群体之间的差异是由于只有有限数量的基因座。(2)我们设计了一种方法，使用多态性倒位在DNA水平上搜索有益的突变。利用这种技术，我们调查了美国和日本的几个自然种群。作为探针，使用包括ADH基因座的DNA片段（约10Kb）。到目前为止，已经发现了一个有益突变的候选者。这是位于ADH编码区的3'侧的约3Kb的插入。(3)使用第二染色体中的自发和现有突变，检查X连锁结构基因的活性是否被突变，特别是位于其它染色体中的多基因突变改变，并且获得阳性结果。(4)我们已经报道了淀粉酶的诱导与适合度之间存在正相关关系，并试图从DNA水平上获得其依据。（5）通过比较1970年采集的种群和自然种群中采集的蝇类，研究了P元素入侵后种群的动态变化。采用原位杂交技术、无菌试验和遗传负荷试验。

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.