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6-Azathymine

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M B Pedersen – One of the best experts on this subject based on the ideXlab platform.

  • The dominant mutation Suppressor of black indicates that de novo pyrimidine biosynthesis is involved in the Drosophila tan pigmentation pathway.
    Molecular Genetics and Genomics, 1993
    Co-Authors: Jožica Piškur, D Kolbak, Lars Sondergaard, M B Pedersen

    Abstract:

    A deficiency in the production of β-alanine causes the black (b) phenotype of Drosophila melanogaster. This phenotype is normalized by a semi-dominant mutant gene Su(b) shown previously to be located adjacent to or within the rudimentary (r) locus. The r gene codes for three enzyme activities involved in de novo pyrimidine biosynthesis. Pyrimidines are known to give rise to β-alanine. However, until recently it has been unclear whether de novo pyrimidine biosynthesis is directly coupled to β-alanine synthesis during the tanning process. In this report we show that flies carrying Su(b) can exhibit an additional phenotype, resistance to toxic pyrimidine analogs (5-fluorouracil, 6-Azathymine and 6-azauracil). Our interpretation of this observation is that the pyrimidine pool is elevated in the mutant flies. However, enzyme assays indicate that r enzyme activities are not increased in Su(b) flies. Genetic mapping of the Su(b) gene now places the mutation within the r gene, possibly in the carbamyl phosphate synthetase (CPSase) domain. The kinetics of CPSase activity in crude extracts has been studied in the presence of uridine triphosphate (UTP). While CPSase from wild-type flies was strongly inhibited by the end-product, UTP, CPSase from Su(b) was inhibited to a lesser extent. We propose that diminished end-product inhibition of de novo pyrimidine biosynthesis in Su(b) flies increases available pyrimidine and consequently the β-alanine pool. Normalization of the black phenotype results.

  • The dominant mutation Suppressor of black indicates that de novo pyrimidine biosynthesis is involved in the Drosophila tan pigmentation pathway.
    Molecular & general genetics : MGG, 1993
    Co-Authors: Jožica Piškur, D Kolbak, Lars Sondergaard, M B Pedersen

    Abstract:

    A deficiency in the production of beta-alanine causes the black (b) phenotype of Drosophila melanogaster. This phenotype is normalized by a semi-dominant mutant gene Su(b) shown previously to be located adjacent to or within the rudimentary (r) locus. The r gene codes for three enzyme activities involved in de novo pyrimidine biosynthesis. Pyrimidines are known to give rise to beta-alanine. However, until recently it has been unclear whether de novo pyrimidine biosynthesis is directly coupled to beta-alanine synthesis during the tanning process. In this report we show that flies carrying Su(b) can exhibit an additional phenotype, resistance to toxic pyrimidine analogs (5-fluorouracil, 6-Azathymine and 6-azauracil). Our interpretation of this observation is that the pyrimidine pool is elevated in the mutant flies. However, enzyme assays indicate that r enzyme activities are not increased in Su(b) flies. Genetic mapping of the Su(b) gene now places the mutation within the r gene, possibly in the carbamyl phosphate synthetase (CPSase) domain. The kinetics of CPSase activity in crude extracts has been studied in the presence of uridine triphosphate (UTP). While CPSase from wild-type flies was strongly inhibited by the end-product, UTP, CPSase from Su(b) was inhibited to a lesser extent. We propose that diminished end-product inhibition of de novo pyrimidine biosynthesis in Su(b) flies increases available pyrimidine and consequently the beta-alanine pool. Normalization of the black phenotype results.

U. Stottmeister – One of the best experts on this subject based on the ideXlab platform.

  • Photolysis of metribuzin in oxygenated aqueous solutions
    Chemosphere, 1998
    Co-Authors: U. Raschke, G. Werner, H. Wilde, U. Stottmeister

    Abstract:

    Abstract The photochemical behaviour of metribuzin [4-amino-6-(1.1-dimethylethyl)-3-methylthio-1.2.4-triazin-5(4H)-one] and its known metabolites desaminometribuzin (DA), diketometribuzin (DK) and desaminodiketometribuzin (DADK) was investigated in aqueous oxygenated solutions at various pH values. The photochemical degradation of metribuzin over time and the formation and further fate of DA, DK and DADK were elucited. Both side-chain degradation and ring opening were detected as a result of photolysis. Six unknown metabolites as a result of side-chain degradation, including 6-azauracile, 6-Azathymine and 4-aminosubstituted derivatives, were identified as very stable photodegradation products. Furthermore, some inorganic and organic ionic compounds were detected such as monocarboxylic, dicarboxylic and ketocarboxylic acids formed by side-chain degradation and ring cleavage.

  • Photodecomposition of 4-amino-1,2,4-triazin-3,5-diones and -thiones in oxygenated aqueous solutions
    Journal of Photochemistry and Photobiology A: Chemistry, 1998
    Co-Authors: U. Raschke, G. Werner, H. Wilde, U. Stottmeister

    Abstract:

    Abstract The photodecomposition of newly synthesized 4-amino-1,2,4-triazinthione 1 and -dione 2 was examined in oxygenated aqueous solutions at various pH values. The degradation pathway of these compounds was compared with the photochemical decomposition of the herbicide metribuzin. Side-chain degradation by deamination, decarboxylation, sulfoxidation and dealkylation is typical for photolysis. Structurally similar compounds display substantial differences with respect to degradation. The pH value has an accelerating or inhibiting effect on the degradation rate. After the rapid formation of basic metabolites by the deamination of 1 and the decarboxylation of 2, selective decomposition takes place in alkaline and acidic solutions, whereas a non-selective course was detected under neutral conditions. The radicalic mechanisms of important reaction steps are discussed. Several metabolites with intact heterocyclic ring systems were identified as photochemically stable final products by the addition of a standard compound, such as 6-azauracile or 6-Azathymine. In contrast to side-chain degradation, ring cleavage was only observed after long irradiation times. Carboxylic and ketocarboxylic acids as well as some inorganic ions were identified in the irradiated solution as the degradation products of side-chain degradation and ring cleavage.

Jožica Piškur – One of the best experts on this subject based on the ideXlab platform.

  • The dominant mutation Suppressor of black indicates that de novo pyrimidine biosynthesis is involved in the Drosophila tan pigmentation pathway.
    Molecular Genetics and Genomics, 1993
    Co-Authors: Jožica Piškur, D Kolbak, Lars Sondergaard, M B Pedersen

    Abstract:

    A deficiency in the production of β-alanine causes the black (b) phenotype of Drosophila melanogaster. This phenotype is normalized by a semi-dominant mutant gene Su(b) shown previously to be located adjacent to or within the rudimentary (r) locus. The r gene codes for three enzyme activities involved in de novo pyrimidine biosynthesis. Pyrimidines are known to give rise to β-alanine. However, until recently it has been unclear whether de novo pyrimidine biosynthesis is directly coupled to β-alanine synthesis during the tanning process. In this report we show that flies carrying Su(b) can exhibit an additional phenotype, resistance to toxic pyrimidine analogs (5-fluorouracil, 6-Azathymine and 6-azauracil). Our interpretation of this observation is that the pyrimidine pool is elevated in the mutant flies. However, enzyme assays indicate that r enzyme activities are not increased in Su(b) flies. Genetic mapping of the Su(b) gene now places the mutation within the r gene, possibly in the carbamyl phosphate synthetase (CPSase) domain. The kinetics of CPSase activity in crude extracts has been studied in the presence of uridine triphosphate (UTP). While CPSase from wild-type flies was strongly inhibited by the end-product, UTP, CPSase from Su(b) was inhibited to a lesser extent. We propose that diminished end-product inhibition of de novo pyrimidine biosynthesis in Su(b) flies increases available pyrimidine and consequently the β-alanine pool. Normalization of the black phenotype results.

  • The dominant mutation Suppressor of black indicates that de novo pyrimidine biosynthesis is involved in the Drosophila tan pigmentation pathway.
    Molecular & general genetics : MGG, 1993
    Co-Authors: Jožica Piškur, D Kolbak, Lars Sondergaard, M B Pedersen

    Abstract:

    A deficiency in the production of beta-alanine causes the black (b) phenotype of Drosophila melanogaster. This phenotype is normalized by a semi-dominant mutant gene Su(b) shown previously to be located adjacent to or within the rudimentary (r) locus. The r gene codes for three enzyme activities involved in de novo pyrimidine biosynthesis. Pyrimidines are known to give rise to beta-alanine. However, until recently it has been unclear whether de novo pyrimidine biosynthesis is directly coupled to beta-alanine synthesis during the tanning process. In this report we show that flies carrying Su(b) can exhibit an additional phenotype, resistance to toxic pyrimidine analogs (5-fluorouracil, 6-Azathymine and 6-azauracil). Our interpretation of this observation is that the pyrimidine pool is elevated in the mutant flies. However, enzyme assays indicate that r enzyme activities are not increased in Su(b) flies. Genetic mapping of the Su(b) gene now places the mutation within the r gene, possibly in the carbamyl phosphate synthetase (CPSase) domain. The kinetics of CPSase activity in crude extracts has been studied in the presence of uridine triphosphate (UTP). While CPSase from wild-type flies was strongly inhibited by the end-product, UTP, CPSase from Su(b) was inhibited to a lesser extent. We propose that diminished end-product inhibition of de novo pyrimidine biosynthesis in Su(b) flies increases available pyrimidine and consequently the beta-alanine pool. Normalization of the black phenotype results.