In a previous study (in press), we have shown that the + d -bem gene does not participate directly in the reaction of pteridine metabolism, but it seems to control the system that maintains the pteridine compound within the hypodermal cells. A hypodermis has been presented that the +d-lem gene controls the production of a specific protein that is an important factor in combining with yellow pigments (2-amino-4-hydroxy-6-lactyl-7, 8-dihydropter.idine) and in keeping them within the cells. To confirm this hypothesis the present experiments were conducted.I. Materials and Methods. The test insects were four wild (normal) strains, C 124, N 124, Daizo and P 22 (+m/+1; leem + d -dem/ +(1-lem), the lemon strain (lem/lem; +d-lem/+d-lem) and the dilute lemon strain (lemllem; d-lemld-lem).(1) Preparation of chromo granules. A large amount of spherical granules, that contain yellow pigments and isoxanthopterin, occur in fresh hypodermal cells of larvae of the strains lemon and dilute lemon.The presence of these chromogranules in the hypodermal cells gives a yellow color to the larvae (Sasaki 1959, Tsujita 1961. Similarly, a large amount of spherical granules, that contain isoxanthopterin, can be observed in fresh hypodermal cells of larvae of the normal strain. These chromogranules were purified by a new method described in another paper, and lyophilized.(2) Paper electrophoresis.A pellet (10 mg) of the lyophilized sample of purified granules was mixed thoroughly under refrigeration with 1 ml distilled water and then centrifuged at 15,000 r.p.m. for 40 minutes.A small amount (0.05 ml) of the supernatant was painted on the line of application of Toyo filter paper No. 51 (26 X 12.5 cm) that was used for the paper electrophoresis.Electrophoresis was carried out for 5-6 hours at pH 8.6 and 8.8 in Veronal buffer (p=O.05) with 0.3 mA/26 cm. The protein bands were stained with bromophenol blue (B.P.B.). Prior to the staining of the protein bands, the localization of substances that showed fluorescence, such as isoxanthopterin and the yellow pigment, was observed by exposing the paper to ultraviolet light.(3) High voltage electrophoresis. In order to detect the presence 1) Contribution from the National Institute of Genetics, Japan No. 474.
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