Association of DNA with melanin granules.

Melanin granules were isolated from the Cloudman S91 mouse melanoma and from Amphiuma liver in highly purified form, as judged by electron microscopy and the lack of a mitochondrial enzyme marker. The granules from both tissues contained small amounts of DNA (less than or equal to 1% of the cell content) that was distinguished from nuclear DNA by the broadness of its buoyant density band in cesium chloride, by its sedimentation rate, and by a two-phased melting curve. The melanosome DNA could not be distinguished from nuclear and mitochondrial DNA by the amount of tritiated thymidine incorporated. The results are discussed and the suggestion made that the melanin DNA may provide the information that led to the production of the granules.