No abstract

Sixteen cultures of continuous human cell lines were tested for oncornaviruses. Six cultures spontaneously released theviruses into the culture fluid. Five cultures released the virusesafter treatment with 5-bromodeoxyuridine or mitomycin C. Five cultures were negative. The viruses belonged to the B and Ctypes of oncornaviruses. Possible origin of the viruses is discussed.

No abstract

Cells of transplantable ascitic hepatoma originally induced in The possible correlation between the synthesis of uf-globulin and the ability of tissue culture cells to induce tumor is discussed.One of the peculiarities of experimental and spontaneous hepatomas is the production of embryonal serum protein, orf-globulin, which is not synthesized by the liver cells of adult animal (Abelev et al., 1963;Tatarinov, 1965; Grabar et al., 1966;Abelev, 1965). Hepatoma cells have been shown to retain the ability to synthesize upglobulin in tissue culture (Abelev et al., 1963;Abelev, 1965).Preliminary experiments demonstrated that cells of such cultures could synthesize not only uf-globulin but also other serum proteins-albumin and P,.,-globulin (cf. Abelev, 1965). Hepatoma cells in tissue culture, capable of synthesizing serum proteins, offer a convenient system for the study of a number of organospecific functions of malignant and normal liver cells, such as the interrelation between protein synthesis and the growth and proliferation of a cell, the problem of differentiation and dedifferentiation of a liver cell in the tissue culture, and many others.Data on stable cultures of mouse ascitic hepatoma XXIIa and on some of their cultural, biochemical and biological properties are given below.

The oncornaviruses isolated from continuous human cell lines and the Mason-Pfizer virus share a common group-specific antigen that is revealed in the immunodiffusion test. They have no common antigens with the mouse mammary tumor virus.