The liver nucleic acid incorporation of adenine-8-C14 during azo dye carcinogenesis.

Brown and associates (2, 9) conclusively demon strated that isotopically labeled adenine was in corporated into the purines of the nucleic acids of normal tissues. The results of these and other in vestigators indicated that the uptake of the labeled compound into the cytoplasmic ribonucleic acid (RNA) was considerably greater than that into the desoxyribonucleic acid (DNA). In re generating liver or in tumors, however, the in corporation into DNA was enhanced. Several in vestigators have found that the nuclear RNA had a rapid turnover of the isotope when labeled compounds were injected or fed in the diet. Barnum and Huseby (1) reported that the rate of incorporation of P32 into the nuclear RNA of mouse liver was extremely high. The specific activ ity of this fraction was greater than that of phospholipids and also that of the microsomal RNA. Davidson and Mclndoe (6) observed that the RNA of nuclei isolated after the administration of P32 had a higher specific activity than the DNA. Following administration of P32 to rats,