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  • 1
    Electronic Resource
    Electronic Resource
    The ommochrome biosynthetic pathway in Drosophila melanogaster: The head particulate phenoxazinone synthase and the developmental onset of xanthommatin synthesis (1976)
    Springer
    Biochemical genetics 14 (1976), S. 1077-1090 
    Details
    ISSN: 1573-4927
    Keywords: xanthommatin synthesis ; phenoxazinone synthase ; eye pigmentation ; Drosophila
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Particulate fractions from the heads of Drosophila melanogaster catalyze the conversion of o-aminophenols to phenoxazinones. This particulate enzyme is stimulated by Mn2+. It has a number of features which distinguish it clearly from the Mn2+-dependent activity found in the soluble fraction. The particulate enzyme has a characteristic developmental pattern, showing a marked increase in activity at about the time of onset of xanthommatin synthesis. In addition, it is much reduced in activity in a number of xanthommatin-deficient mutants (v, cn, st, cd, and w). We believe that the head particulate enzyme is involved in xanthommatin biosynthesis and that the developmental onset of synthesis of this pigment is brought about by the synthesis or activation of this enzyme.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00485139
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Control of drosopterin synthesis in Drosophila melanogaster: Mutants showing an altered pattern of GTP cyclohydrolase activity during development (1978)
    Springer
    Biochemical genetics 16 (1978), S. 13-26 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila melanogaster ; GTP cyclohydrolase ; development ; pteridine biosynthesis ; mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The reaction catalyzed by GTP cyclohydrolase is the first unique step of pteridine biosynthesis in Drosophila melanogaster and is therefore likely to be an important control point. GTP cyclohydrolase activity varies during development, showing two distinct peaks of activity—one at pupariation and a much larger peak at emergence. Most of the early pupal enzyme is located in the body region, whereas in late pupal and early adult life most of the activity is found in the head. Mixing experiments indicate that developmental changes in activity are not due to changes in the level of a direct effector of GTP cyclohydrolase. The mutants raspberry and prune show an increased GTP cyclohydrolase activity at pupariation relative to wild type, but a decreased enzyme activity at emergence. The changes in GTP cyclohydrolase activity are reflected in changes in pteridine levels in these mutants. Several lines of evidence suggest that neither locus is the structural gene for GTP cyclohydrolase. The raspberry and prune gene products may play a specific role in regulating GTP cyclohydrolase activity during development.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484381
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Xanthommatin biosynthesis in wild-type and mutant strains of the Australian sheep blowfly Lucilia cuprina (1978)
    Springer
    Biochemical genetics 16 (1978), S. 1153-1163 
    Details
    ISSN: 1573-4927
    Keywords: xanthommatin synthesis ; eye color mutants ; Lucilia cuprina ; development
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The synthesis of eye pigments has been studied in the seven eye color mutants of the Australian sheep blowfly, Lucilia cuprina. Six appear to be affected primarily in the synthesis of xanthommatin. In wild type, the onset of xanthommatin biosynthesis occurs midway through metamorphosis. Developmental patterns of accumulation of the xanthommatin precursors tryptophan, kynurenine, and 3-hydroxykynurenine have also been established for wild type. By determining the levels of these precursors in late pupae of the mutants, it has been shown that the mutant yellowish accumulates excess tryptophan and the mutant yellow accumulates excess kynurenine. The implications of these results—that yellowish lacks tryptophan oxygenase, thus failing to convert tryptophan to kynurenine, and that yellow lacks kynurenine hydroxylase (blocked in the conversion of kynurenine to 3-hydroxykynurenine)—have been confirmed. This has involved in vitro assays of tryphophan oxygenase and precursor feeding experiments. The precursor accumulation patterns are less clear for the other mutants.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484536
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    Paper (German National Licenses)
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  • 4
    Electronic Resource
    Electronic Resource
    Developmental patterns of 3-hydroxykynurenine accumulation in white and various other eye color mutants of Drosophila melanogaster (1977)
    Springer
    Biochemical genetics 15 (1977), S. 1049-1059 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; eye pigmentation ; 3-hydroxykynurenine accumulation ; white mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Several points of biochemical similarity between white and scarlet mutants suggest that both are defective in the transport of xanthommatin precursors. In both, accumulation of 3-hydroxykynurenine is negligible during larval life and occurs at only a slow rate during adult development. Larvae of both mutants also excrete 3H-3-hydroxykynurenine and 3H-kynurenine rapidly, which probably accounts for the normal levels of kynurenine during larval life. 3-Hydroxykynurenine levels are abnormal in all white mutants which were studied, although in two alleles which are strongly pigmented (w sat and w col) accumulation is enhanced rather than diminished. In w a, larval accumulation is normal but accumulation during adult development is greatly diminished, suggesting that this mutation has a tissue-specific effect. Similar levels were found in zeste females. Of the 11 other eye color mutants tested, abnormal levels of 3-hydroxykynurenine were found in eight. In four of these (claret, light, lightoid, and pink), larval accumulation is negligible, suggesting that these have defects in the kynurenine transport system like scarlet and white. In three others, however (brown, karmoisin, and rosy), accumulation during larval life is enhanced. In cardinal accumulation is normal during larval life but is excessive during adult development. This evidence supports the suggestion that the cd mutation blocks the final step of xanthommatin synthesis.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484496
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    Paper (German National Licenses)
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