GENETIC AND BIOCHEMICAL STUDIES ON AMINO ACID COMPOSITIONS AND COLOR MANIFESTATION IN PUPAL SHEATHS OF INSECTS

Previously we (Seki 1962, Fukushi and Seki 1965) established the relationship between the pupal color of Bombyx mori, Drosophila virilis and Musca domestica and the content of β-alanine in their pupal sheaths. Further information was added to the correlation between color manifestation and β-alanine in the pupal sheaths of insects. 1. In the pupal sheath of the wild type strain of Drosophila melanogaster, β-alanine was found. But β-alanine was absent in pupal sheaths of strains of black adult body color mutants like b and e, although their pupal colors were not black. 2. The content of β-alanine in pupal sheaths of Musca and Drosophila strains, whose adult body colors are paler than those of the wild strains, is higher than in those of the wild type strains. 3. A double mutant, bwb; bp, of M. domestics, shows yellowish-brown body color in the adult and the pupal color is dark black. From the pupal sheath of this strain, a small amount of β-alanine was detected. 4. A phenocopy of the wild type pupal sheath of M. domestica was obtained by rearing larvae of the bp mutant in β-alanine-containing medium at the 4th-day larval stage. Pupal colors of the phenocopy individuals ranged from black to the brown of wild type. A clear correlation was recognized between the grade of color of the phenocopy pupae and the content of β-alanine in the pupal sheaths. 5. By means of reflux and proteinase digestion, a small amount of β-alanine was liberated from the pupal sheath of the wild type strain, but its solubilization behavior was different from that of other amino acids. 6. In the wild type strain of Musca, free β-alanine in the body fluid rapidly increased at the very young pupal stage, but such a phenomenon was not observed in the bp mutant.