シヨウジ∃ウバエの複眼における小眼形成物質に関する研究,特に棒眼形質の発現機構について
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概要
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The Bar-eyed mutant of Drosophila melanogaster which is due to a small duplication in the sex chromosome reduces the facet number (normal=550-750, Bar=50-130). The heterozygous female has 360±facets, so that this mutant is recognized as semidominant. The facet number of the heterozygous female, however, varies considerably according to the strains, e.g. l-45×B (coiso)=665±, B(coiso)×e^<11>=428±, B(coiso)×Canton-S=265± and B(coiso)×g^2=192±. Experiments so far performed have indicated that the facet number of the heterozygous female seems to have some relations with the Mg content of the strains used for the crossing. In an experiment in which the 50-hours old larvae were raised in the medium containing 3 or 4 percent of Mgacetate under 25℃. The facet numbers of flies especially in the males of the B; e^<11> strain considerably increased to almost like wild types (table 1, fig. 3, plate 1). Larvae of three Bar-eyed stocks such as B(bb)-1, B(coiso) and B; e^<11> strains were treated with more than eighty kinds of organic and inorganic substances to examine the effect of these substances to facet forming action. Nearly all of them did show some effects, out of them ammonium lactate was the most effective one and the Bar eyes were recovered completely to the same extent as that of the wild eyes in both sexes (tables 12, 13, 18, 19 and plates 1, 2). Many kinds of substances show a marked difference in their effects among B(bb)-1, B(coiso) and B; e^<11> strains. This phenomenon leads me to the conclusion that Mg would act as a catalytic cofactor for the protein and nucleic acid syntheses. Among effective substances, uracil, thymine and adenosine would participate in the nucleic acid synthesis, whereas urea, acid amides, and amino acids etc. would be utilized as substrates for protein synthesis of eye-discs in Bar mutant. Sugars, pyruvic acid, citric acid, malic acid, ATP etc. might be used as energy sources in the TCA-cycle. To summarize the present status of these experiments, it seems very probable that in this mutant the protein and nucleic acid syntheses are slightly inhibited at least in the eye-discs (fig.4), so that the cell divisions in them are more or less hampered, and this would be the reason why the Bar-eyed mutant has small numbers of facets in the eyes. Facet forming substances of ey^2 and bar-3 mutants in D. melanogaster have also been discussed briefly.
- 1957-01-25