Alterations in polyadenylated messenger ribonucleic acid from free and total polysomes of rat hepatoma

Abstract

We examined the homology between polysomal polyadenylated ribonucleic acid (mRNA) populations of hepatoma 252, a tumor which is deficient in the synthesis of plasma proteins, and those of normal and regenerating rat liver. Hybridization of polyadenylated mRNA populations with homologous or heterologous complementary deoxyribonucleic acids showed that mRNA from total and free polysomes from hepatoma 252 lack sequences which are present in normal or regenerating liver. Although there are obvious differences in the abundance of sequences between tumor and normal or regenerating liver polysomal mRNA, we did not detect, with the techniques used in this work, tumor-specific sequences. Analysis of hybridization curves using derivative plots did not reveal the presence in tumor mRNA of a high complexity class not present in normal liver. We conclude that alterations in mRNA populations of free and total polysomes of this tumor primarily reflect processes of genetic restriction rather than the derepression of previously unexpressed genes.

Expression of a Cellular Oncogene During Liver Regeneration

“…We analyzed the extent o nomic expression, levels of mess RNA (mRNA), and RNA sequence complexity and homology. We concluded that there are quantitative differences, but no obvious qualitative differences, between mRNA populations of normal and regenerating liver (17,18). The pattern of expression of the ras gene conforms to these conclusions.…”

Development of the Place Principle: Acoustic Trauma

“…Possible mechanisms for the ontogenetic shift in the spectral properties of the cochlea include (i) age-related changes in the dimensional, mass, or stiffness characteristics of the basilar membrane, resulting in mechanical changes; and (ii) chtanges in the properties of the stereocilia, resulting in different "filtering" characteristics. EDWIN 17. In embryos, the shell overlying the air space was removed, exposing the chick's head.…”

Secretion of albumin and alpha-foetoprotein by dimethylsulphoxide-stimulated hepatocellular carcinoma cells

“…Hepatoma cells tend to be genetically restricted relative to normal hepatic tissue (Derman et al, 1981;Scholla et al, 1981), displaying a lower mRNA complexity and lacking many of the normally abundant mRNA sequences characteristic of the adult liver. Inhibition of the in vitro expression of certain growth properties characteristic of the malignant phenotype (focus formation, attainment of high population densities) by DMSO treatment of BW77-1 cells (Higgins & Borenfreund, 1980;Higgins, 1982), thus, reflects alterations in hepatic protein synthesis similar to those observed during glucocorticoid-mediated regulation of liver-specific protein production (Brown and Papaconstantinou, 1979) and which accompany maturation of foetal hepatocytes in vitro (Freeman et al, 1981 …”