DNA supercoil introduced to directly visualize individual plectonemes along supercoiled DNA which would further allow to study the interactions of DNA processing proteins with supercoiled DNA. In that study, Sytox Orange (an intercalating dye), has been used to induce supercoiling on surface tethered DNA molecules. DNA supercoiling is important for DNA packaging within all cells. Because the length of DNA can be thousands of times that of a cell, packaging this genetic material into the cell or nucleus (in eukaryotes) is a difficult feat. Supercoiling of DNA reduces the space and allows for DNA to be packaged. In prokaryotes, plectonemic supercoils are
DNA methylation to occur at about 0.006% of cytosines. In contrast, DNA methylation is widely distributed in Physarum polycephalum where 5-methylcytosine makes up as much as 8% of total cytosine Adenine or cytosine methylation is part of the restriction modification system of many bacteria, in which specific DNA sequences are methylated periodically throughout the genome. A methylase is the enzyme that recognizes a specific sequence and methylates one of the bases in or near that sequence. Foreign DNAs (which are not methylated in this manner) that are introduced into the cell are degraded by sequence-specific restriction enzymes and cleaved. Bacterial genomic DNA