Mitochondrial DNA (mtDNA) sequence variation was examined in eight taxa of the African rodent family Bathyergidae, as well as in two taxa representative of the Old-World hystricognathid rodent families Petromyidae and Thryonomyidae. A total of 812 bp, constituting domains I-III of the 12S ribosomal rRNA gene, were compared for each taxon. The high levels of intrafamilial mtDNA sequence divergen...

A mouse skin squamous cell carcinoma induced by topical application of the direct-acting alkylating agent beta-propiolactone contains an activated H-ras oncogene with an A----T transversion at the second nucleotide of codon 61. The mutation was detected in NIH3T3 transfectant and original tumor DNA by an XbaI restriction enzyme polymorphism and confirmed by oligonucleotide "mismatch" hybridizat...

Using hepatic RNA polymerase I and II from either normal or N-2-hydroxy-2-acetylaminofluorene (N-OH-AAF)-treated rats or E. coli RNA polymerase, the degree of misincorporation of noncomplementary nucleotides was assessed with the synthetic templates, poly(dG-dC).poly(dG-dC) and poly (dA-dT).poly(dA-dT). The predominant base-pair transformation that was transcribed in the presence of Mg++ or Mn+...

In recent years, Mycoplasma pneumoniae strains that are clinically resistant to macrolide antibiotics have occasionally been encountered in Japan. Of 76 strains of M. pneumoniae isolated in three different areas in Japan during 2000 to 2003, 13 strains were erythromycin (ERY) resistant. Of these 13 strains, 12 were highly ERY resistant (MIC, > or =256 microg/ml) and 1 was weakly resistant (MIC,...

The molecular epidemiology of p53 mutations allows the possibility of correlating particular mutations with specific environmental carcinogens and establishing one step in the causal pathway between exposure to carcinogens and the development of cancer. A striking example is the G > T transversion at the third base pair of codon 249 observed in liver cancer patients possibly exposed to high lev...

Models of amino acid substitution were developed and compared using maximum likelihood. Two kinds of models are considered. "Empirical" models do not explicitly consider factors that shape protein evolution, but attempt to summarize the substitution pattern from large quantities of real data. "Mechanistic" models are formulated at the codon level and separate mutational biases at the nucleotide...

【Introduction】 8-Oxo-2 ́-deoxyguanosine (8-oxo-dG) is a representative nucleoside damage that is formed by oxidation of 2 ́-deoxyguanosine (dG) with reactive oxygen species (ROS), and its presence has been linked to aging, cancer, etc [1]. Unlike dG, 8-oxo-dG forms stable base pairs with both 2 ́-deoxycytidine (dC) and 2 ́-deoxyadenosine (dA). Based on the base-pairing properties of 8-oxo-dG, DNA p...

OBJECTIVES To determine the mechanism of high-level resistance to fluoroquinolone antimicrobials in toxin-A-negative, toxin-B-positive (A- B+) Clostridium difficile isolates. METHODS Following culture 16-23S PCR ribotyping was used to determine genomic relationships between A- B+ C. difficile isolates. Antimicrobial susceptibilities were determined using Etests in the presence and absence of ...

A novel mutator locus in Escherichia coli was identified from a collection of random transposon insertion mutants. Several mutators in this collection were found to have an insertion in the dgt gene, encoding a previously characterized dGTP triphosphohydrolase. The mutator activity of the dgt mutants displays an unusual specificity. Among the six possible base pair substitutions in a lacZ rever...

Cerebrotendinous xanthomatosis (CTX) is an autosomal recessive lipid storage disease caused by mutations in the cytochrome P450(27) (CYP27) gene. This disease is characterized by the accumulation of a bile alcohol, cholestanol, in diverse tissues. Accumulation in the central nervous system leads to neurological dysfunction including dementia, spinal cord paresis, and cerebellar ataxia. Accumula...