DNA methylation is one of the best characterized epigenetic modifications. In mammals it is involved in various biological processes including the silencing of transposable elements, regulation of gene expression, genomic imprinting, and X-chromosome inactivation. This article describes how DNA methylation serves as a cellular memory system and how it is dynamically regulated through the action...

Targeted modification of genomic DNA (gDNA) in a cell permanently changes its phenotype. Numerous methods to modify target portions of gDNA in eukaryotes have been developed, and several have found practical application (e.g., homologous recombination-utilized modification in mouse ES cells). The past decade has seen active research both in oligonucleotide-directed modifications (where the olig...

Genomic DNAs of 14 strains from seven species of the spirochete Leptospira were resistant to cleavage by the restriction endonuclease RsaI (5'-GTAC). A modified base comigrating with m4C was detected by chromatography. Genomic DNAs from other spirochetes, Borrelia group VS461, and Serpulina strains were not resistant to RsaI digestion. Modification at 5'-GTAm4C may occur in most or all strains ...

Gene delivery vectors based on retroviral or lentiviral particles are considered powerful tools for biomedicine and biotechnology applications. Such vectors require modification at the genomic level in the form of rearrangements to allow introduction of desired genes and regulatory elements (genotypic modification) as well as engineering of the physical virus particle (phenotypic modification) ...