The thymus cells of rats have been shown to raise the intracellular concentration of glycine but not of leucine above that of their suspending medium during a 1-hour incubation period. At low concentrations of glycine, the thymus cells concentrated glycine about one-half as well as did Ehrlich hyperdiploid ascites cells.

Protein synthesis and intracellular concentration of amino acids could be depressed by a number of nonionic detergents. Protein synthesis was more sensitive to the effect of detergents than was concentrating ability and might be markedly reduced while the ability to concentrate amino acids remained normal.

The depression of these two activities was demonstrated by means of labeled glycine and leucine. The degree of depression was constant even over a wide range of concentration of glycine. The depression was also dependent upon the amount of detergent present.

Under the conditions used, normal thymus cells were shown to synthesize more protein than did Ehrlich hyperdiploid ascites cells, when either glycine or leucine was used.

Protein synthesis was more sensitive to the action of nonionic detergents than was the permeability of the cells to eosin Y. The detergents caused an increase of intracellular water in both normal and tumor cells. The use of nonionic detergents to differentiate the surface of neoplastic and normal cells was successful only in a small quantitative way.

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This investigation was supported in part by a grant (No. C 2867) from the National Cancer Institute, National Institutes of Health, United States Public Health Service, and by a grant from the Massachusetts Division, American Cancer Society.

This is Publication #1021 of the Cancer Commission of Harvard University.

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