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  • 1
    Electronic Resource
    Electronic Resource
    Molecular and genetic studies on the euchromatin-heterochromatin transition region of the X chromosome of Drosophila melanogaster (1984)
    Springer
    Chromosoma 89 (1984), S. 218-227 
    Details
    ISSN: 1432-0886
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine
    Notes: Abstract A recombinant Charon 4 bacteriophage has been isolated on the basis of RNAs which are enriched in the head of the adult Drosophila melanogaster and hence are likely to be of neural origin. The cloned insert maps to the near vicinity of the uncoordinated locus in polytene chromosome band 19E8. This band is within the transition zone between the euchromatic and heterochromatic regions of the X chromosome, a region which has been well characterized cytogenetically. The insert contains both repetitious and low copy number sequences, some of which vary extensively in both frequency and restriction fragment size between different laboratory strains. One particular family of moderately repeated sequences occurs predominantly in divisions 19 and 20 of the X chromosome and perhaps the distally located X heterochromatin. The molecular landscape surrounding the initial entry point contains many repeated sequences and is thus unlike those observed in most published chromosomal walks. The possible significance of the presence of repeated sequence families in the distinct properties of this region are discussed.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00295003
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  • 2
    Electronic Resource
    Electronic Resource
    A biochemical study of the scarlet eye-color mutant of Drosophila melanogaster (1975)
    Springer
    Biochemical genetics 13 (1975), S. 273-282 
    Details
    ISSN: 1573-4927
    Keywords: Drosophila ; scarlet mutant ; xanthurenic acid ; 3-hydroxykynurenine
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract 3-Hydroxykynurenine is virtually absent from st larvae but accumulates during adult development in the puparium. Over the period of adult emergence, the accumulated 3-hydroxykynurenine is excreted so that st adults contain none. Larvae of st fed on tryptophan-C 14 medium produce labeled 3-hydroxykynurenine, at a reduced rate, perhaps, compared to wild type. Xanthurenic acid levels in st pupae are similar to those in wild type. Thus the failure of st larvae to accumulate 3-hydroxykynurenine does not seem to be due either to an inability to synthesize this compound or to an excessive rate of its conversion to xanthurenic acid. Rather, it appears that the mechanism of 3-hydroxykynurenine storage during larval life is defective, so that this compound is excreted at an abnormally high rate. The inability of the pigment cells of the eyes of st to synthesize xanthommatin may result from a similar defect in their ability to take up or store 3-hydroxykynurenine.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00486022
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  • 3
    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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  • 4
    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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  • 5
    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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  • 6
    Electronic Resource
    Electronic Resource
    Functions of the white and topaz loci of Lucilia cuprina in the production of the eye pigment xanthommatin (1980)
    Springer
    Biochemical genetics 18 (1980), S. 643-653 
    Details
    ISSN: 1573-4927
    Keywords: Xanthommatin synthesis ; transport mutants ; Lucilia cuprina ; eye color mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract The white and topaz eye color mutants of L. cuprina are defective in the production of the brown screening pigment xanthommatin. Both white and topaz mutants were found to be unable to accumulate xanthommatin precursors in the larval malpighian tubules, correlating with their reduced early pupal level of this metabolite. In addition, white mutants showed reduced rates of accumulation of kynurenine and 3-hydroxykynurenine in the adult eyes. Another mutant strain, grape, was also defective in its ability to accumulate these xanthommatin precursors in the eyes, although accumulation was normal in the larval tubules. In contrast, the topaz mutants were found to be normal in eye accumulation, although tubule accumulation was markedly abnormal. These properties of the white and topaz mutants of L. cuprina are compared with those of the white and scarlet mutants of D. melanogaster, and it seems likely that in the two species these genes are involved with the uptake or storage of xanthommatin precursors in specific tissues.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484582
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  • 7
    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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  • 8
    Electronic Resource
    Electronic Resource
    Isolation and biochemical analysis of a temperature-sensitive scarlet eye color mutant of Drosophila melanogaster (1979)
    Springer
    Biochemical genetics 17 (1979), S. 149-158 
    Details
    ISSN: 1573-4927
    Keywords: xanthommatin synthesis ; scarlet mutants ; Drosophila melanogaster ; temperature-sensitive mutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Abstract Six new EMS-induced scarlet mutants were selected. Four of these were partially pigmented, with xanthommatin levels ranging from 12% to 45% of normal. In one (st 754ts), pigment production was temperature sensitive; the level of xanthommatin changed from less than 10% of normal at 29 C to more than 70% at 18 C. In all of the new mutants tested, the level of early pupal 3-hydroxykynurenine was as low as low as that in st 1. Thus reduced larval accumulation of this metabolite also appears to be a characteristic feature of scarlet mutants. Temperature-pulse and temperature-shift experiments were carried out with st 754ts to determine the temperature-sensitive period for the scarlet gene during development. The major sensitive period commenced prior to the onset of pigmentation and was over before adult emergence. Thus the initiation of xanthommatin synthesis is not brought about by the activation of the scarlet gene. In similar experiments carried out with a temperature-sensitive white mutant (w bl), a similar temperature-sensitive period was obtained.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00484480
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  • 9
    Electronic Resource
    Electronic Resource
    Sections notices (1968)
    Springer
    Potato research 11 (1968), S. 67-69 
    Details
    ISSN: 1871-4528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02365165
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  • 10
    Electronic Resource
    Electronic Resource
    Report of the Meeting of the Section Utilization at Dublin (Ireland), 13–17 September, 1970 (1970)
    Springer
    Potato research 13 (1970), S. 361-365 
    Details
    ISSN: 1871-4528
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02358282
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