The effect of cations on C-band formation in human chromosomes.

A number of salt solutions were tested for their ability to replace 2 X SSC in the production of C-bands with the so-called CT technique. Those containing monovalent cations, except for the ones with Ag+ ions, were capable of inducing C-bands in Ba(OH)2-pretreated human chromosomes. Cesium cations were the most effective in this respect. In contrast to the effect of the monovalent cations studied, di- or polyvalent cations (and Ag+ cations) were incapable of producing C-bands, but appeared to stabilize the Ba(OH)2-induced reverse-banding pattern, This stabilizing effect was obtainable with relatively low cation concentrations and persisted even when C-band-producing cations were present at the same time. The experiments clearly show that the cations present during salt incubations, generally used in the CT- and several other banding methods, can exert a pronounced influence on chromosome behavior.