Extremely underwound chromosomal DNA in nucleoids of mouse sarcoma cells.
The superhelical properties of chromosomal DNA from cells of a mouse sarcoma were investigated in neutral sucrose gradients containing ethidium bromide. Removal of negative supercoiling from the DNA of the sarcoma cells required a substantially higher dye concentration than was necessary in the case of DNA from cultured mouse fibroblasts. The calculated value of the mean superhelical density in malignant cells (sigma = -0.14) appears abnormally high compared with the value (sigma = -0.09) obtained for DNA of mouse fibroblasts. Chromosomal DNA from mouse sarcoma cells is therefore concluded to be highly deficient in helical turns.
D000818:Animals; D002466:Cell Nucleolus / Q000032:analysis; D002499:Centrifugation, Density Gradient; D002875:Chromosomes / Q000032:analysis*; D004273:DNA, Neoplasm / Q000032:analysis*; D004996:Ethidium / Q000494:pharmacology; D051379:Mice; D008815:Mice, Inbred Strains; D012513:Sarcoma, Experimental / Q000032:analysis*
D004273:DNA, Neoplasm; D004996:Ethidium