On the significance and mechanism of the binding of 2-acetylaminofluorene and N-hydroxy-2-acetylaminofluorene to rat-liver ribonucleic acid in vivo.

Previous reports that radioactivity was bound to liver RNA after administration of 2-acetylaminofluorene-9-14C or N-hydroxy-2-acetylaminofluorene-9-14C in species susceptible to the carcinogenic action of 2-acetylaminofluorene have been con firmed. Injection of l-hydroxy-2-acetylaminofluorene-l-14C, a noncarcinogenic metabolite of 2-acetylaminofluorene, did not result in any binding of radioactivity to rat-liver RNA. On the other hand, 2-acetylaminofluorene-9-14C was bound to liver RNA of the rabbit, a species which does not contract liver cancer upon administration of 2-acetylaminofluorene. In addition, Af-hydroxy-2-acetylaminofluorene-9-14C was bound to liver RNA of the guinea pig, which does not develop liver cancer after administration of Ar-hydroxy-2-acetylaminofluorene. Sucrose density gradient sedimentation studies of purified rat-liver RNA, isolated after injection of 2-acetylaminofluorene9-14C of high specific radioactivity, revealed that there was uniform labeling of the ribosomal RNA but that the soluble RNA had a specific radioactivity which was 2-2.5 times that of ribo somal RNA. Following administration of either AT-hydroxy-2-acetylaminofluorene-9-14Cor Ar-hydroxy-2-acetylaminofluorene-l'-14C, it was