Competitive DNA-RNA hybridization of nuclear and microsomal RNA in normal, neoplastic, and neonatal liver tissue.

The nuclear and microsomal RNA of three minimal de viation hepatomas and 10-day-old neonatal rat liver were compared by standard DNA-RNA competitive hybridiza tion techniques. nRNA from 5123C hepatoma and 10-day neonatal liver lack sequences present in adult liver nuclear RNA. These missing sequences appear to be identical in part. nRNA from the slowly growing Morris 9618 hepa toma could not be distinguished from adult liver nRNA. The microsomal RNA from this tumor and the 7800 hepa toma both showed sequences to be missing which were pres ent in adult liver microsomal RNA, whereas microsomal RNA from the Morris 5123C hepatoma could not be dis tinguished from adult liver microsomal RNA in relation to their competitive efficiency for liver nuclear RNA. The significance of these findings in relation to transport of mRNA from nucleus to cytoplasm and in cytoplasmic mRNA stabilization is considered.