[Studies on the appearance of chalone proteins in the subcellular fractions from some bovine tissues. I. Antimitotic activity, the level of proteins, nucleic acids and glycoproteins in healthy cattle and in that affected with leukosis].

The occurrence of chalones has been studied in the liver, spleen and lymph nodes of cattle. The cells of those organs were fractionated. After removing the nuclei and mitochondria the residue was subdivided by means of the cesium chloride gradient into smooth and rough microsomes. The chalones were investigated in supernatants from these two groups of microsomes. In the obtained supernatants, the levels of proteins, nucleic acids and glycoproteins were estimated. The protein composition was analysed by means of disc electrophoresis on polyacrylamide, and the antigenic relationship of these proteins with the serum ones was studied using immunoelectrophoresis. The biological value of the separated fractions was investigated by means of the mitosis inhibition test in mice. The experimental groups of these animals were injected intraperitoneally with different cellular subfractions without or with colcemide. The control groups were treated with colcemide only or with physiological solution of NaCl. The subcellular fractions were separated from the tissues of healthy cattle and of that affected with leukosis. It was found that a protein showing chalone activity appears in all cellular subfractions derived from the tissues of healthy animals; its highest concentration was found in the supernatants from rough microsomes of the spleen and from smooth microsomes of the lymph nodes. The antimitotic effect was observed at the concentration of 100-200 microg of protein in 0.1 ml. This effect seems to be connected with glycoproteins. In the supernatants from tissues of leukotic animals, there was observed a decrease of the antimitotic effect. A mixture of proteins was present in the supernatants, which was demonstrated by means of polyacrylamide electrophoresis. These proteins showed and antigenic relationship with the proteins of blood serum. This can be concluded from their precipitation with the sera against the bovine serum proteins in the immunoelectrophoresis test. The chalone of the spleen seems to be different from that of the lymph nodes. The experiment showed the occurrence of an antimitotic effect with the non-homologous proteins, i.e. the chalone from the liver inhibited the mitotic divisions of the cells of the spleen, thymus and lymph nodes in mice. In this experiment, a mixture of proteins was used. The purification of an active chalone will be the subject of further investigations.