The methylation-sensitive restriction endonucleases HpaII and HhaI and the methylation-insensitive enzyme MspI were used to examine the methylation status of the 5' end of the human apolipoprotein B gene in cells in which the gene is transcriptionally active, such as HepG2 and CaCo-2 cells, and in HeLa cells, which do not express the gene. Several CCGG and GCGC sequences present in the region f...

The 16S rDNA genotypes among the family Vibrionaceae were determined using PCR/RFLP analysis. Five tetrameric restriction enzymes (HhaI, DdeI, RsaI, Sau3AI and MspI) were used for RFLP analysis and adequate numbers of informative bands were obtained from each enzyme. Twenty-seven genotypes were obtained from 49 type and reference strains including 35 species. Nineteen species could be assigned ...

Molecular tools based on rRNA (rrn) genes are valuable techniques for the study of microbial communities. However, the presence of operon copy number heterogeneity represents a source of systematic error in community analysis. To understand the types and magnitude of such bias, four commonly used rrn-based techniques were used to perform an in silico analysis of a hypothetical community compris...

Different mutagenic effects are generated by DNA oxidation that implies the formation of radical cation states (so-called holes) on purine nucleobases. The interaction of DNA with proteins may protect DNA from oxidative damage owing to hole transfer (HT) from the stack to aromatic amino acids. However, how protein binding affects HT dynamics in DNA is still poorly understood. Here, we report a ...

A new method of in vitro recombination was employed to construct plasmids containing lac promoter fragments 64 bp and 144 bp long. The 64 bp HpaII-HhaI fragment contains the binding site for the catabolite activator protein (CAP). The HpaII-HaeIII 144 bp fragment includes the binding sites for RNA polymerase, the lac repressor and CAP. The method utilizes the ability of T4 DNA polymerase to mak...

DNA methylation plays important roles via regulation of numerous cellular mechanisms in diverse organisms, including humans. The paradigm bacterial methyltransferase (MTase) HhaI (M.HhaI) catalyzes the transfer of a methyl group from the cofactor S-adenosyl-L-methionine (AdoMet) onto the target cytosine in DNA, yielding 5-methylcytosine and S-adenosyl-L-homocysteine (AdoHcy). The turnover rate ...

This paper analyzes the extent of enzymatic methylation of DNA in P815 cells cultured for several cell cycles in the presence of 1 mM L-ethionine by use of the bacterial restriction enzymes HpaII, MspI, HhaI, HaeII, and AvaI. The results obtained suggest that the extent of methylation of DNA is decreased during L-ethionine treatment and that the degree of this inhibition varies among different ...