Role and oxidation state of the pterin molybdenum cofactor of molybdenum enzymes: Studies of a Drosophila melanogaster xanthine dehydrogenase (rosy) variant, G1011E

ABSTRACT A convenient method is described for the intracistronic mapping of genetic sites responsible for electrophoretic variation of a specific protein in Drosophila melanogaster. A number of wild-type isoalleles of the rosy locus have been isolated which are associated with the production of electrophoretically distinguishable xanthine dehydrogenases. Large-scale recombination experiments were carried out involving null enzyme mutants induced on electrophoretically distinct wild-type isoalleles, the genetic basis for which is followed as a nonselective marker in the cross. Additionally, a large-scale recombination experiment was carried out involving null enzyme rosy mutants induced on the same wild-type isoallele. Examination of the electrophoretic character of crossover and convertant products recovered from the latter experiment revealed that all exhibited the same parental electrophoretic character. In addition to documenting the stability of the xanthine dehydrogenase electrophoretic character, this observation argues against a special mutagenesis hypothesis to explain conversions resulting from allele recombination studies.

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The rosy locus in Drosophila melanogaster: xanthine dehydrogenase and eye pigments.

Genetics ◽

10.1093/genetics/129.4.1099 ◽

1991 ◽

Vol 129 (4) ◽

pp. 1099-1109 ◽

Cited By ~ 4

Author(s):

A G Reaume ◽

D A Knecht ◽

A Chovnick

Keyword(s):

Drosophila Melanogaster ◽

Structural Integrity ◽

Present Report ◽

Specific Interaction ◽

Pigment Granule ◽

Ultrastructural Localization ◽

Xanthine Dehydrogenase ◽

Pigment Formation ◽

Antibody Staining ◽

Pigment Granules

Abstract The rosy gene in Drosophila melanogaster codes for the enzyme xanthine dehydrogenase (XDH). Mutants that have no enzyme activity are characterized by a brownish eye color phenotype reflecting a deficiency in the red eye pigment. Xanthine dehydrogenase is not synthesized in the eye, but rather is transported there. The present report describes the ultrastructural localization of XDH in the Drosophila eye. Three lines of evidence are presented demonstrating that XDH is sequestered within specific vacuoles, the type II pigment granules. Histochemical and antibody staining of frozen sections, as well as thin layer chromatography studies of several adult genotypes serve to examine some of the factors and genic interactions that may be involved in transport of XDH, and in eye pigment formation. While a specific function for XDH in the synthesis of the red, pteridine eye pigments remains unknown, these studies present evidence that: (1) the incorporation of XDH into the pigment granules requires specific interaction between a normal XDH molecule and one or more transport proteins; (2) the structural integrity of the pigment granule itself is dependent upon the presence of a normal balance of eye pigments, a notion advanced earlier.

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