Motoo Tsusué

Purification and identification of a yellow pteridine characteristic of the larval colour of the Kiuki mutant of the silkworm, Bombyx mori.

Abstract A yellow pteridine characteristic of the Kiuki mutant of the silkworm Bombyx mori was isolated from the larval integument by successive column chromatography systems consisting of ECTEOLA-cellulose, P-Sephadex, and Sephadex G-25. Based on mass spectra, the IR spectrum, ORD spectrum and degradation experiments, the chemical structure of the yellow pigment was established as 7,8-dihydro-6-( l )-lactyllumazine sepialumazine. The compound has been found to be present in the integument of other strains of Bombyx mori. The yellow colour of the Kiuki larvae is caused by sepialumazine accumulation in the integument. Both sepiapterin deaminase and sepiapterin reductase were assayed in mutant Kiuki, mutant lemon and normal type silkworms. A higher activity of sepiapterin deaminase was found in the Kiuki mutant than in normal silkworms. The accumulation of sepialumazine in Kiuki larvae may be due to the high activity of this enzyme.

Occurrence of xanthommatin containing pigment granules in the epidermal cells of the silkworm, Bombyx mori

Abstract A new type of pigment granule was found in the epidermal cells of the quail mutant of the silkworm, Bombyx mori. Electron microscopic observation shows this granule to be dense and distinct from the translucent pteridine granule. After the granules were isolated by sucrose density gradient centrifugation, the pigment was extracted and identified as xanthommatin. Xanthommatin localizes in the pigment granules binding with a protein. By SDS-polyacrylamide gel electrophoresis, the molecular weight of the pigment protein was estimated to be 13 kDa. The pigment granules may have a role in the biosynthesis and accumulation of xanthommatin.

Occurrence of biopterin in the wings ofMorpho butterflies

A blue fluorescent compound was isolated fromMorpho butterfly wings. Based on thin layer chromatographic, UV and CD-spectrophotometric and HPLC analyses, the blue fluorescent compound was identified as L-erythro biopterin. Biopterin is a major component of blue fluorescent pteridines in bothM. sulkowskyi andM. adonis. Pterin and isoxanthopterin can also be detected as minor components in these species. This paper is the first to report the presence of biopterin in butterfly wings.

Juvenile hormone control of larval colouration in the silkworm, Bombyx mori: Characterization and determination of epidermal brown colour induced by the hormone

Abstract Larval colouration in the silkworm, Bombyx mori , is under hormonal control. Juvenile hormone injection at certain critical times during the moulting cycle induces a colour change in larval epidermis from greyish white to yellowish brown at ecdysis. This epidermal brown pigment was isolated from larvae injected with the juvenile hormone analogue (JHA) methoprene. Based on redox behaviour, visible and near ultraviolet absorption spectra and R f values after thin layer chromatography in various solvents, the brown pigment was identified as xanthommatin. Epidermal xanthommatin was assayed by the use of high pressure liquid chromatography (HPLC). 3-Hydroxykynurenine, the direct precursor of the pigment, and other epidermal pigments such as sepialumazine and riboflavin were also determined by HPLC. The higher the dose of injected hormone, the greater were the quantities of xanthommatin and 3-hydroxykynurenine found in larval integument. However, the amounts of sepialumazine and riboflavin were little affected by the hormone. These facts indicate that JHA acts on tryptophan metabolism and that xanthommatin is yet another pigment which causes characteristic colouration of silkworm larval integument.

The nature of the seasonal colour dimorphism in the scorpion fly, Panorpa japonica thunberg

Abstract The scorpion fly, Panorpa japonica, displays a seasonal colour dimorphism by changing from black to yellow in the adult state. The yellow pigment in the integument and haemolymph of the adult fly was identified as sepiapterin, while the black integument pigment was found to be melanin. After analysis of sepiapterin content by high performance liquid chromatography and determination of total haemolymph volume by [carboxyl-14C]inulin, it was shown that sepiapterin levels in the haemolymph and integument varied greatly both in the two colour types of insects and in the two sexes. Photometric analysis of melanin content showed that melanin levels correlated negatively with sepiapterin levels. These quantitative differences in sepiapterin and melanin fully explain the colour dimorphism in the insect.

A Comparative Study of Urinary Xanthopterin and Neopterin in Liver Diseases

By adsorption to activated charcoal, various pteridine derivatives in human urine are oxidized to xanthopterin. Following this oxidation, xanthopterin in urine from healthy subjects and from patients with liver diseases was assayed by high performance liquid chromatography. The mean values for xanthopterin in healthy subjects were 532 +/- 116 mumol/mol creatinine (mean +/- SD) in males and 585 +/- 153 mumol/mol creatinine in females; the difference was statistically significant (p < 0.01). Xanthopterin concentrations in patients with liver disease were significantly higher than those in normal subjects. When compared with urinary neopterin, which is a marker of activated cell immunity, xanthopterin was significantly increased even in fatty liver disease. These findings suggest that increased concentrations of urinary xanthopterin in liver diseases reflect not only the status of activated cell-mediated immunity, but also injury to liver cells.

The occurrence of 7-hydroxybiopterin in the scorpion fly,Panorpa japonica

A purple fluorescent compound was isolated from the integument of scorpion flies. Based on paper chromatographic, UV-spectrophotometric, fluoreometric and HPLC analysis, as well as a chemical color test and various degradation tests, the compound was identified as 7-hydroxybiopterin.

Relationship between Seasonal Colour Dimorphism and Pteridines in the Scorpion Fly, Panorpa japonica, Thunberg

The combination of the morphological and biochemical approaches shows that sepiapterin is characteristically located at the pigment granules in the integument of the insect. We report here that the contents of various pteridines and the activities of related enzymes (GTP-cyclohydrolase I, 6-pyruvoyl-tetrahydropterin synthase and sepiapterin reductase) were measured at several stages after emergence of both yellow type fly and black one.

Characterization of a dihydropterin deaminase from Drosophila melanogaster

Abstract A highly specific dihydropterin deaminase was discovered in Drosophila melanogaster and was purified 60-fold over that of the crude extract. The enzyme specifically deaminates 7,8-dihydropterin forming the corresponding 7,8-dihydrolumazine. The enzyme does not deaminate the following compounds: pterin, xanthopterin, dihydroxanthopterin, sepiapterin, isosepiapterin, biopterin, dihydrobiopterin, neopterin, 6-hydroxymethylpterin, 6-methylpterin, 7-methylpterin, 6,7-dimethylpterin, pterin-6-carboxylic acid, isoxanthopterin, isoxanthopterin-6-carboxylic acid, 6-methylisoxanthopterin, 6-methyl-tetrahydropterin, drosopterin and isodrosopterin. The pH optimum of the enzymatic reaction is approximately 8.5 and the K m value is 1.3 mM. The molecular weight of the enzyme is 73,000 as estimated by gel filtration. The non-fluorescent product of the reaction, 7,8-dihydrolumazine, was non-enzymatically oxidized to blue fluorescent 6-hydroxylumazine.

Urinary and Serum Pteridines in Liver Diseases

Summary The aim of this mini-review is to show the usefulness of pteridines as clinical markers. We assayed urinary neopterin and xanthopterin levels in liver disease. Total pterins were oxidized by active carbon to yield xanthopterin. Urinary neopterin levels were elevated in patients with chronic active hepatitis and in those with chronic persistent hepatitis but not in patients with alcohol-induced liver disease or in those with non-alcoholic fatty liver. Urinary xanthopterin levels were elevated in chronic active hepatitis and alcohol- induced liver disease, but not in chronic persistent hepatitis and non-alcoholic fatty liver. Urinary neopterin levels were high in infectious diseases involving activated cell-mediated immunity, and increased urinary xanthopterin reflects liver-cell damage. We also compared plasma neopterin values in anti-hepatits C virus antibody (anti-HCV) -positive or - negative donors with elevated alanine aminotransferase (ALT). Plasma neopterin values of anti-HCV-negative donors with elevated ALT were the same as those of healthy groups. These results show that the ALT elevation in anti-HCV-negative donors is attributable mainly to steatosis due to excess body weight and/or alcohol consumption, rather than viral infection. During the course of these studies, we were also able to identify esophageal carcinoma in the very early stage by measuring urinary pteridine levels. Our results indicate that pteridines are clinically useful indicators. In particular, neopterin may be used as a means of screening for unknown viral infection.