The effect of SH-SS transition in the structural organization of mitotic chromosomes

Human lymphoid cell cultures were treated with 2,2'-dithiodipyridine, a thiol reacting agent which produces SS bridges inside the living cells. After 1 to 4 h treatment chromosome preparations were made. The chromosomes acquired a peculiar segmentation along the chromatids. The results suggest that the alteration might arise from a direct reaction of the agent with special chromosomal proteins. The resistance of treated chromosomes to alkali-heat treatment used in C-banding technique was different from that of untreated chromosomes. This prefixational procedure seems to be advantageous in analysing both the chromosome organization and the banding mechanism.