The banding pattern produced by restriction endonucleases in mouse chromosomes.

The metaphase chromosomes of mouse have been treated with the restriction endonucleases Alu I, Mbo I, Hae III and Eco RII and subsequently stained with the DNA-specific dye Ethidium bromide. A striking correspondence between previous biochemical findings and our cytological results has been noticed with Alu I, Mbo I and Hae III, which were capable of digesting all but the DNA localized at the centric constitutive heterochromatic areas. Digestion with Eco RII, on the contrary, resulted in cytological data which apparently did not fit in with the biochemical results previously obtained by digesting the DNA of this species with the same enzyme. It is postulated that factors such as chromatin organization, in addition to DNA base sequence, can determine the results we report.