Genetical and Biochemical Studies on the Red and Yellow Eye Pigments of <i>Drosophila melanogaster</i>

Abstract

Single and double or triple eye color mutants of Drosophila melanogaster were used for the experiments. The relative amounts of eye pigments, extracted from heads without proboscis by means of“double extraction”method, were estimated by photometrical measurement. Several kinds of pteridines, which were contained mainly in eyes and testes, were separated by paper chromatography and their amounts were measured fluorometrically. Their relative amounts could be estimated by comparing them with each other.The eye pigments of Drosophila are composed of three kinds, red, yellow and brown. Red and yellow pigments have been proved to be pteridine derivatives, and a metabolic pathway from yellow to red was suggested on the basis of experimental results. A metabolic relationship between several pteridines was indicated on the basis of the influence of various mutant genes on the amount of pteridines.Since pteridines are located in eyes and in testes, a remarkable sexual difference was detected; their total amount in male bodies was about 20 times as large as in female bodies. The genic actions of both w and bw strains are assumed to block up the supply of the common pteridine precursor. The route of supply is more or less depressed by the action of ca, ry and Hnr-3 genes. The homozygous Hnr-3 fly was considered to have incomplete conversion of sepiapterin to tetrahydropterin, because of reduced activity of pterine reductase. The cl and Hnr-1 genes inhibit considerably the transformation of tetrahydropterin into red pigment, but the se gene blocks it completely. From all results, a scheme on pteridine metabolism of Drosophila was devised.