[14C]Formate labelling of bases of nucleic acids in respiring slices of rat tissues

Abstract

When slices of rat liver of spleen were allowed to respire in Krebs-Ringer solution containing C14-formate, radioactivity was detected in the adenine and guanine of RNA and the adenine, guanine and thymine of DNA. The labeling of the RNA purines took place when the slices were incubated in either phosphate or bicarbonate buffer. Labeling was optimal at pH > 7.5. Under similar conditions, the purines of the RNA of slices of guinea-pig liver were also labeled. The labeling was inhibited by KCN (0.03 [image]), 2:4-dinitrophenol (10-4 [image]), or under anaerobic conditions. Adenine and guanine of RNA were also labeled in slices of other organs. For the rat, the descending order of activity was: spleen, liver, kidney, pancreas, brain, heart. Labeling of the purines of RNA was not affected by a previous fast of 24 hours or by removing the pituitary gland.