アナナス猩々蠅の遺傳
スポンサーリンク
概要
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As has been ascertained by H.KIKKAWA, namely, that Drosophila ananassae is synonymous with D.caribbea (V.Drosophila Information Service No.3, 1935; No.4, 1935), the first mutant that appeared in this species should be an autosomal recessive, curved, as found by STURTEVANT (1921) in D.caribbea. Some time since then, I began to study the genetics of D.ananassae (1934, 1935a, 1935b, 1935c, 1936), using flies collected in Tokyo that were supposed to have been imported from Formosa. At the same time KAUFMANN (1936) and KIKKAWA (1936) have recently published some cytological studies of the species. Nine mutant characters were newly found, th origins and characteristics of which are described. Scute (sc), achaete (ac), lethal-3 (1-3), and yellow (y) appeared as sex-linked recessives. Genes missing (ms), extended (ex), and Off (Off) belong to the second chromosome, of which Off is dominant, the homozygous flies being viable and distinguishable from the heterozygous ones. The remainder, ski-III (sk-III) and Minute-IIIc (M-IIIc), belong to the third chromosome. Adding these new genes, I have obtained 23 mutants. Their linkage groups were investigated, with chromosome maps, though their loci were tentative. But no mutant gene has ever been found in the fourth chromosome, even from all the mutants including those found by KIKKAWA. Sexual differences of expression of genes seem to be recognized more frequently in D.ananassae than in other species of Drosophila. Among 23 genes there were 6 of such cases, except bobbed, the sexual difference of which could be explained by the relation between the X-and Y-chromosomes. The first example is Interrupted (Ir), a sex-linked dominant, already reported by MORIWAKI (1934, 1935a); namely, males with X^<Ir> Y had crossveinless-like Interrupted or incomplete veins, while homozygous Interrupted females were crossveinless-like and completely sterile. The report on the next case, crumploid, has also been published (MORIWAKI, 1935b). The degree of the expression of crumploid, a sex-linked recessive, seemed to vary from false normal to crumploid with lethal effect, while in the male the expression was reduced considerably, resulting in excess of males. Another sex-linked recessive, scute, is the third example, its expression being stronger in females. Besides these, the autosomal recessive mutants, ski-III and extended, also presented sexual differences, in both of which manifestation of the gene was weakened in the male. The last example is a case of balloon expression of Plexate (MORIWAKI, in press). An inheritable character manifesting a balloon-like expression additionally to Plexate shows also a sexual difference: it is reduced by half in the male. From these data we can notice the common fact that the expression of the gene has always been reduced more or less in the male, although it has not yet been determined whether the causes are common or not. A list of mutants so far obtained in D.ananassae is presented.
- 1936-10-15