1,721,077 research outputs found
The 4-nitroquinoline 1-oxide mutational spectrum in single stranded DNA is characterized by guanine to pyrimidine transversions.
No full text4-Nitroquinoline-1-oxide is a potent mutagen and carcinogen which induces two main guanine adducts at positions C8 and N2. In ds or ss damaged DNA the ratio C8/N2 adducts is 1:2 and 8-10:1, respectively. In bacteria and yeast 4NQO has been shown to be a base substitution mutagen acting at G residues inducing mainly G to A transitions. We determined the mutational spectrum induced by the 4NQO metabolite, acetoxy-4-aminoquinoline 1-oxide, in the M13lacZ'/E. coli lacZ delta M15 alpha complementation assay using ssDNA. Among 68 Ac-4HAQO induced mutants, G to Pyr transversion was the most frequent base substitution observed. By comparison with dsDNA based systems, our data suggest that dGuo-C8-AQO induces G to Pyr transversions. A mechanism to explain how this lesion may induce transversions is proposed
Enantioselective pummerer-type rearrangement of gamma-fluoro-beta-enaminosulfoxides: Efficient approach to chiral non-racemic alpha,alpha-N,S-disubstituted ketals of beta-fluoro-pyruvaldehydes
No full textThe enantioselective synthesis of chiral non-racemic alpha,alpha-N,S-disubstituted ketals of beta-fluoro-pyruvaldehydes 2 has been efficiently accomplished by one-per treatment of the gamma-fluoro-beta-enaminosulfoxides 1 with trifluoroacetic anhydride and then with silica gel. Two fast and enantioselective rearrangements should be involved in the reaction. A change of reaction conditions or the use of other promoters, like acyl chlorides, can produce achiral vinyl sulfides
On the products obtained from -oxygen substituted crotonaldehyde in fermenting baker's yeast
No full textGoing Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
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