Several banding techniques, especially G-banding, suggest that there are both qualitative and quantitative variations in the interaction of DNA and proteins along the length of metaphasechromosomes.Thechromatinofactivegenesis generally considered to be more accessible to nuclease attack than is inactive chromatin. Consistent with this nucleases preferentially digest R-bands and T-bands of intact mitotic chromosomes, with G-bands and C-bands refractive to digestion. The extent of chromatin packaging in theinterphasenucleus alsodiffersbetween chromosome bands. C-band positive heterochromatin remains visibly condensed through interphase. FISH has shown that over the 150kb to 1Mb size range G-band chromatin is more tightly packaged than that of R-bands.