[Differential reactions of heterochromatin and euchromatin to beta-mercaptoethanol]

The responses of interphase and mitotic chromatins to beta-mercaptoethanol were studied. The reaction of X-chromatin of interphase nuclei was expressed in the increase of the percentage of cells with X-chromatin. beta-Merceptoethanol removed a condensing effect induced by spermine on the diffused chromatin of interphase cultured fibroblasts. beta-Mercaptoethanol caused a differential staining of metaphase chromosome when added to the cultured cells 0.5 hours prior to fixation. The treatment of chromosome preparations with different concentrations of beta-merceptoethanol and for different times led to different staining of chromosomes with asur--eosin. Low concentrations and/or short treatment induced G-banding, most typical with moderate concentrations. Higher concentrations and longer treatment prevented G-staining due to the loosening of G-segments.