Isolation of folded chromosomes from Mycoplasma hyorhinis.

Folded chromosomes were isolated from Mycoplasma hyorhinis. When examined by electron microscopy, these molecules show variability of loop size, number of loops, total contour length and degree of twisting of the DNA. Sedimentation velocity was unaltered after treatment with RNase, proteinase K, SDS, temperatures up to 65 degrees C and NaCl concentrations from 0.1 M to 4 M.