metrizamide and Cell-Transformation--Neoplastic

A one-step isopycnic density gradient centrifugation procedure is described for purification of highly viable and homogeneous tumor cells from a variety of solid mouse tumors. Mechanically suspended cells are layered onto preformed continuous gradients of medium 199-buffered 7--33% metrizamide (density range 1.05--1.20 g/cu. cm) isoosmotic with mouse plasma and centrifuged for 30 min. Large numbers of tumor cells, generally 85--95% viable and free from 80--95% of contaminating host lymphoid and phagocytic cells and erythrocytes, were consistently recovered from fractionated thymomas, melanomas, and fibrosarcomas. By a variety of criteria, cell surface and other biological properties of gradient-purified tumor cells were normal.

Topics: Animals; Cell Separation; Cell Transformation, Neoplastic; Centrifugation, Density Gradient; Female; Fibrosarcoma; Lung Neoplasms; Lymphocytes; Melanoma; Metrizamide; Mice; Mice, Inbred AKR; Mice, Inbred BALB C; Mice, Inbred C57BL; Neoplasm Transplantation; Neoplasms, Experimental; Phagocytes; Thymoma

Isopycnic sedimentation in metrizamide gradients has shown that mouse-liver histones bind co-operatively to both homologous and bacterial DNA's. However, at low input ratios of histone to DNA, two types of stable complex are formed, depending on the histone concentration. One complex contains half as much histone as DNA while the other contains approximately equal amounts of histone and DNA. At high input ratios of histone to DNA extra histone is bound giving complexes containing up to twice as much histone as DNA. Poly-L-lysine and protamine were also found to bind co-operatively to DNA.

Topics: Animals; Cell Transformation, Neoplastic; Centrifugation, Isopycnic; DNA; DNA, Bacterial; DNA, Neoplasm; Escherichia coli; Friend murine leukemia virus; Histones; Liver; Metrizamide; Mice; Nucleoproteins; Polylysine; Protamines; Protein Binding