Abstract
The term ‘Akajuku’ means that the silkworm body becomes reddish at the matured larval stage, and TANAKA reported that the character was manifested by gene Rs. The present paper deals with the development and the nature of ‘Akajuku’ pigments of Japanese race No.1 Nichi 1), which is presumed to have Rs gene.
1)‘Akajuku’ pigments appear in the 4th moulting period, and are mostly deep in colour tone from 3rd day of the 5th instar to the matured larval stage. The appearance of this pigment is different from that of the pigment of Japanese race No.122.
2) By the histological observation, it has been ascertained that pigments distribute as red pigment granules at the basement part of the epidermis.
3) The Rf value (solvent: formic acid) is 0.82 (Table 2) and the absorption curve has a maximum at about 450mμE (Fig. 2). The orange colour of the pigment extract changes yellow by oxidation with H2O2, and turns pink by reduction with Na2S2O4. From these respects, it may be considered that this pigment is closely related to+chrome-1, which is a tryptophan derivative.
4) Notable accumulation of 3-hydroxykynurenine in the integument as in the case of Japanese race No.122 was not recognized. From this it may be supposed that 3-hydroxykynurenine is converted to the present pigment without long staying in the integument after being produced.
