Selective digestion of mouse chromosomes with restriction endonucleases. I. Scaffold-like structures and bands by electron microscopy

Mouse chromosomes from the L929 cell line have been digested with the restriction endonuclease HaeIII and analyzed by electron microscopy. Results show a different effect of the enzyme depending on the conditions of the digestion. Thus, while chromosomes digested in suspended cells show a double scaffold-like structure per chromatid, a similar banding to that found in chromosomes treated for light microscopy is obtained when chromosomes are digested on grids. Some aspects concerning the capacity of the cleaved DNA to be removed from the chromatin are discussed.