DNA-binding fluorochromes: correlation between C-banding of mouse metaphase chromosomes and hydrogen bonding to adenine–thymine base pairs

Summary us non-rigid and bow-shaped cationic fluorochromes exist which bind to chromatin DNA, but only some of them are able to selectively label pericentromeric heterochromatin (C-bands) in metaphase chromosomes. Likewise, some DNA ligands allow the recognition of adenine–thymine sequences establishing hydrogen bonds with acceptor atoms in the minor groove. In the present study, we have employed cationic fluorochromes based on a variety of chemical groups to analyze comparatively their potential to demonstrate C-bands, as well as the relationship between this feature and structural parameters of fluorochromes such as curvature radius and hydrogen-bonding ability. Only fluorochromes that bind DNA by hydrogen bonds demonstrated the characteristic C-banding pattern in mouse metaphase chromosomes (together with a weak G/Q-banding), whereas the other (non-hydrogen-bonding) cationic fluorochromes produced uniform emission without any visible banding.