The incorporation of formate-C¹⁴ into the nucleic acids of rats with regenerating liver and Novikoff hepatoma

A comparison has been made of the formate-C¹⁴ incorporation into the nucleic acid purines and thymine of regenerating rat liver and Novikoff hepatoma in vivo. The effects of these tissues on one another, and on the host tissues has been studied. The utilization of formate by the nucleic acids of Novikoff hepatoma and regenerating rat liver was not significantly altered in animals containing both of these rapidly dividing tissues. The results indicated that the demand for formate by one of the rapidly growing tissues did not lower the uptake of formate by the nucleic acids of the other tissue. Furthermore it was indicated that nucleic acid synthesis in regenerating liver did not alter the synthesis of nucleic acids in other tissues. Regenerating liver and Novikoff hepatoma had no effect on the nucleic acid metabolism of the host tissues of animals bearing one or both of these tissues. These results are not completely in agreement with those reported in the literature. In a preliminary experiment a radioactive suspension of Novikoff hepatoma was transplanted into rats. Twenty percent of the injected radioactivity was recovered in the urine during the first 24 hours of tumor growth. The specific activities of the nucleic acid bases of the tumor, obtained after 24 hours of growth, were negligible. These findings indicated that the nucleic acids of the donor tumor suspension were not utilized in the synthesis of the nucleic acids of the growing tumor.Medicine, Faculty ofBiochemistry and Molecular Biology, Department ofGraduat