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  • Saccharomyces cerevisiae  (12)
  • Mutagen hyper-resistance  (3)
  • Alcohol dehydrogenase  (2)
  • Hyperresistance  (2)
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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Current genetics 19 (1991), S. 429-433 
    ISSN: 1432-0983
    Schlagwort(e): Mutagen hyper-resistance ; Yeast ; Base sequence ; Gene disruption
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A multi-copy plasmid containing the SNQ3 gene confers hyper-resistance to 4-nitroquinoline-N-oxide (4NQO), Trenimon, MNNG, cycloheximide, and to sulfometuron methyl in yeast transformants. Restriction analysis, subcloning, and DNA sequencing revealed an open reading frame of 1950 bp on the SNQ3-containing insert DNA. Gene disruption and transplacement into chromosomal DNA yielded 4NQO-sensitive null mutants which were also more sensitive than the wild-type to Trenimon, cycloheximide, sulfometuron methyl, and MNNG. Hydropathic analysis showed that the SNQ3-encoded protein is most likely not membrane-bound, while the codon bias index points to low expression of the gene.
    Materialart: Digitale Medien
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  • 2
    ISSN: 1432-0983
    Schlagwort(e): Saccharomyces cerevisiae ; Mutagen hyperresistance ; Southern, Northern analysis ; Gene transplacement ; Transposon mapping
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The genes SNQ and SFA confer hyperresistance to 4-NQO and FA when present on a multi-copy plasmid in yeast. Both are non-essential genes since transplacement of SNQ by a disrupted snq-0::LEU2 yielded stable and viable haploid integrants. Southern analysis revealed that SNQ and SFA are single-loci genes, and OFAGE analysis showed that they are located on chromosome XIII and IV, respectively. Northern blot analysis of SNQ and SFA revealed poly(A)+ RNA transcripts of 2 kb and 1.7 kb, respectively. Nuclease S 1 mapping showed SNQ to have a coding region of 1.6 kb and SFA, one of 1.3 kb. The 5′ coding regions were determined for both genes, while the 3′ end could only be determined for gene SNQ. Both genes do not appear to contain introns. The SFA locus was also mapped by transposon mutagenesis. Tn10-LUK integrants disrupted the SFA gene function at sites that were determined by subcloning to lie within the SFA transcription unit.
    Materialart: Digitale Medien
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  • 3
    ISSN: 1432-0983
    Schlagwort(e): Mutagen hyper-resistance ; Nitrogen mustard ; Saccharomyces cerevisiae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A screening of haploid yeast strains for enhanced resistance to nitrogen mustard (HN2) yielded a recessive mutant allele, hnm1, that conferred hyper-resistance (HYR) to HN2. Diploids, homo- or heterozygous for the HNM1 locus, exhibit normal wild-type like resistance while homozygosity for hnm1 leads to the phenotype HYR to HN2. The hnm1 mutation could be found in yeast strains proficient or deficient in different DNA repair systems. In these mostly HN2-sensitive haploid repair-deficient mutants, hnm1 acted as a partial suppressor of HN2 sensitivity. All isolated recessive mutations conferring hyper-resistance belonged to a single complementations group. The HYR to HN2 phenotype was maximally expressed in growing cells and was associated with reduced mutability by HN2. HNM1 most probably controls uptake of HN2 which would be impaired in the hnm1 mutants.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Current genetics 11 (1986), S. 211-215 
    ISSN: 1432-0983
    Schlagwort(e): Saccharomyces cerevisiae ; Hyperresistance ; DNA damaging agents ; Genotoxic effects
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary In order to study resistance to DNA damaging agents, yeast DNA segments conferring hyperresistance in this organism to such genotoxic agents were selected for among yeast cells transformed by a yeast genome library based on the multi-copy vector plasmid YEp13. Genetic variants hyperresistant to 4-nitroquinohne-N-oxide, formaldehyde, and alkylating agents were isolated and the respective hyperresistance determinants shown to co-segregate with the vector plasmid. Phenotypical characterization indicated different degrees of resistance, few cases of cross-resistance and differing structural stability of the cloned DNA. By transfer to E. coli and subsequent retransformation of yeast a number of plasmids was shown to stably carry the genetic information for hyperresistance.
    Materialart: Digitale Medien
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  • 5
    ISSN: 1432-0983
    Schlagwort(e): Formaldehyde ; DNA-protein cross-links ; Repair ; Saccharomyces cerevisiae ; Hyperresistance
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The formation and removal of formaldehyde-mediated DNA protein cross-linking was measured by CsCI density gradient analysis in yeast strains of differing resistance to formaldehyde. Wild-type cells and transformants made hyperresistant to formaldehyde by a multi-copy vector containing the yeast SFA gene were specifically labeled in their DNA and incubated in the presence of formaldehyde. Treatment with formaldehyde lead to the formation of equal amounts of DNA protein cross-links; subsequent liquid holding of cells for 24 h resulted in the removal of nearly all DNA protein crosslinks regardless of the original formaldehyde resistance status of the strains.
    Materialart: Digitale Medien
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  • 6
    ISSN: 1432-0983
    Schlagwort(e): Saccharomyces cerevisiae ; Multiple mutants of DNA repair ; Sensitivity to nitrogen mustard and to radiation ; Thermoconditional DNA repair
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Three haploid yeast mutants (snm) sensitive or thermoconditionally sensitive to the DNA cross-linking agent nitrogen mustard (HN2) were crossed with four rad strains representing mutations in the three pathways of DNA dark repair. The resulting haploid double and triple mutant strains were tested for their sensitivity to UV, HN2 and HN1. From the observed epistatic or synergistic interactions of the combinations of mutant alleles we could derive the relation of the SNM1 and SNM2 genes to the postulated repair pathways. Alleles snm1-1 and snml-2 ts were found epistatic to genes of the rad3 group, whereas snm2-1 ts was epistatic to rad6. The snm1 and snm2 mutant alleles interacted synergistically. From these data it is concluded that the SNM1 gene product plays a cross-link specific role in excision repair while the SNM2 gene product may be involved in a system of error-prone repair.
    Materialart: Digitale Medien
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  • 7
    Digitale Medien
    Digitale Medien
    Springer
    Current genetics 29 (1996), S. 437-440 
    ISSN: 1432-0983
    Schlagwort(e): Yeast ; Formaldehyde ; Hyper-resistance ; Alcohol dehydrogenase
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract In an attempt to clone genes involved in resistance to formaldehyde we have screened a genomic library based on the episomal plasmid YEp24 for the ability to increase resistance to formaldehyde in a wild-type strain. In addition toSFA, the gene encoding the formaldehyde dehydrogenase Adh5, an enzyme most potent in formaldehyde de-toxification, we isolated a second plasmid that conferred a less pronounced but significant hyper-resistance to formaldehyde. Its passenger DNA contained the geneADH1, encoding alcohol dehydrogenase 1 (EC 1.1.1.1), which could be shown to be responsible for the observed hyper-resistance phenotype. Construction of anadh1-0 mutant revealed that yeast lacking a functionalADH1 gene is sensitive to formaldehyde. While glutathione is essential for Adh5-mediated formaldehyde de-toxification, Adh1 reduced formaldehyde best in the absence of this thiol compound. Evidence is presented that formaldehyde is a substrate for Adh1 in vivo and in vitro and that its cellular de-toxification employs a reductive step that may yield methanol.
    Materialart: Digitale Medien
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  • 8
    ISSN: 1432-0983
    Schlagwort(e): Key words Psoralen sensitivity ; Cytochrome oxidase ; Saccharomyces cerevisiae ; Oxidative stress
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract The yeast gene PSO7 was cloned from a genomic library by complementation of the pso7-1 mutant's sensitivity phenotype to 4-nitroquinoline-1-oxide (4NQO). Sequence analysis revealed that PSO7 is allelic to the 1.1-kb ORF of the yeast gene COX11 which is located on chromosome XVI and encodes a protein of 28-kDa localized in the inner mitochondrial membrane. Allelism of PSO7/COX11 was verified by non-complementation of 4NQO-sensitivity in diploids homo- and hetero-allelic for the pso7-1 and cox11::TRP1 mutant alleles. Sensitivity to 4NQO was the same in exponentially growing cells of the pso7-1 mutant and the cox11::TRP1 disruptant. Allelism of COX11 and PSO7 indicates that the pso7 mutant's sensitivity to photoactivated 3-carbethoxypsoralen and to 4NQO is not caused by defective DNA repair, but rather is due to an altered metabolism of the pro-mutagen 4NQO in the absence of cytochrome oxidase (Cox) in pso7-1/cox11::TRP1 mutants/disruptants. Lack of Cox might also lead to a higher reactivity of the active oxygen species produced by photoactivated 3-carbethoxypsoralen. The metabolic state of the cells is important for their sensitivity phenotype since the largest enhancement of sensitivity to 4NQO between wild-type (WT) and the pso7 mutant occurs in exponentially growing cells, while cells in stationary phase or growing cells in phosphate buffer have the same 4NQO resistance, irrespective of their WT/mutant status. Strains containing the pso7-1 or cox11::TRP1 mutant allele were also sensitive to the oxidative stress-generating agents H2O2 and paraquat. Mutant pso7-1, as well as disruptant cox11::TRP1, harboured mitochondria that in comparison to WT contained less than 5% and no detectable Cox activity, respectively.
    Materialart: Digitale Medien
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  • 9
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 231 (1992), S. 194-200 
    ISSN: 1617-4623
    Schlagwort(e): Saccharomyces cerevisiae ; DNA repair ; Nitrogen mustard ; Interstrand cross-links ; Nucleotide sequence
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary A 3.2 kb yeast DNA fragment containing the DNA interstrand cross-link-specific repair gene SNM1 has been sequenced. Two genes were identified. SNM1 has an open reading frame of 1983 by and codes for a 661 amino acid protein. Hydrophobic analysis shows that the protein is most probably not directly membrane bound. The second gene, UGX1, has an open reading frame of 573 by coding for a polypeptide of 191 amino acid residues. The two genes are arranged head to head and share a 192 by divergent promoter region that contains three TATAAA motives, two for the SNM1 and one for the UGX1 locus. Gene UGX1 has no apparent influence on the sensitivity of the cell to cross-linking nitrogen mustard, as its disruption in wild type does not increase sensitivity to nitrogen mustard and the presence of multiple copies of the gene fails to complement the nitrogen mustard sensitivity phenotype of snm1 disruption mutants. Northern analysis revealed that the expression of SNM1 yields an average of 0.3 copies/cell of a 2.4 kb transcript, while expression of UGX1 yields higher levels of a 0.8 kb poly(A)+ RNA.
    Materialart: Digitale Medien
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  • 10
    Digitale Medien
    Digitale Medien
    Springer
    Molecular genetics and genomics 241 (1993), S. 680-684 
    ISSN: 1617-4623
    Schlagwort(e): Nitrogen mustard resistance ; Regulation of choline permease ; Co-regulation ; Phospholipid biosynthesis ; Saccharomyces cerevisiae
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Abstract An 815 by region of the promoter of the Saccharomyces cerevisiae gene CTR/HNM1, encoding choline permease was sequenced and its regulatory function analysed by deletion studies in an in-frame promoter-lacZ construct. In addition to the TATA box, a 10 by motif (consensus 5′-CATGTGAAAT-3′) was found to be mandatory for CTR/HNM1 expression. This ‘decamer’ motif is located between nucleotides −262 and −271 and is identical in 9 of 10 by with the regulatory motif found in the S. cerevisiae INO1 and CHO1 genes. Constructs with the 10 by sequence show high constitutive expression, while elimination or alterations at three nucleotide positions, of the decamer motif in the context of an otherwise unchanged promoter leads to total loss of β-galactosidase production. Expression of the CTR/HNM1 gene in wild-type cells is regulated by the phospholipid precursors inositol and choline; no such influence is seen in cells bearing mutations in the phospholipid regulatory genes INO2, INO4, and OPI1. There is no regulation by INO2 and OPI1 in the absence of the decamer motif. However constructs not containing this sequence (promoter intact to positions −213 or −152) are still controlled by INO4. Other substrates of the choline permease, i.e. ethanolamine, nitrogen mustard and nitrogen half mustard do not regulate expression of CTR/HNM1.
    Materialart: Digitale Medien
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