キイロショウジョウバエのヘンナ座位における対立遺伝子作用の生化学的研究

Abstract

The allelism at Henna locus in Drosophila melanogaster was iochemically investigated. From the experlmental, results Henna-recessive alleles seem to be pseudoallelic.Red and yellow eye pigments extracted from male heads with 30 per cent acidic ethanol were estimated photometrically and compared with each other. Various genotypes resulting from allele combinations, regarding the eye pigment formation are in the following order:+/+>+/Hnr-1=+/Hnr-3>Hnr-1/Hnr-1>Hnr-1/Hnr-3=Hnr-3/Hnr-1>Hnr-3/Hnr-3.The separation of pteridines extracted from male heads and bodies was conducted by means of two-dimensional paper chromatography. Relative amounts of the separated pteridines were measured fluorometrically. A positive correlation between the amounts of sepiapterin (SP) and biopterin (BP) was recognized. A striking difference between the alleles was detected in amounts of SP and isoxanthopterin (IXP); the Hnr-3 homozygotes had less IXP and more SP than the other genotypes.The sepiapterin reductase, closely related to the conversion of SP to 2-amino-4-hydroxypteridine (AHP) was remarkably lower activity in Hnr-3 than in the others. Hence, the accumulation of SP in the Hnr-3 flies, especially in testes, was considered to depend upon the low activity of that enzyme.A synthetic pathway of Drosophila pteridines was proposed from the experimental results. The Hnr-3 gene apparently inhibits the process between dihydropteridine (YPH2) and tetrahydropteridine (YPH4), but the Hnr-1 gene does not inhibit this step.