Properties of the inactive ribosomal components in rat liver and hepatoma

1. The relative concentrations of the inactive ribosomal components were compared in normal and regenerating rat liver and in two transplantable rat hepatomas (hepatomas 7800 and 5123D). 2. The size of the ribosomal-subunit pools in normal liver was not significantly affected by partial hepatectomy or neoplasia although, as shown previously, significant changes do occur in the monomer pool. 3. Further, the subunit pools in both liver and hepatoma were not significantly influenced by several treatments that caused dramatic changes in the size of the ribosomal monomer (and dimer) pools. 4. The high concentration of inactive monomers and dimers in the hepatomas appears to arise from limitations at the translational level, since they can be incorporated into pre-existing polyribosomes under the influence of cycloheximide.     

ADDITIONAL OBSERVATIONS ON STEPHANOSPERMUM OVOIDES,A MIDDLE PENNSYLVANIAN SEED

Taylor , Thomas N. (U. Illinois, Urbana.) Additional observations on Stephanospermum ovoides, a Middle Pennsylvanian seed. Amer. Jour. Bot. 49(7): 794–800. Illus. 1962.—Recently additional specimens of Stephanospermum ovoides have been discovered in coal-ball material collected at the New Delta Mine, Absher, Williamson County, Illinois. Stephanospermum ovoides is a radially symmetrical ovoid seed, characterized by a low sclerotestal crown and micropylar beak. The species stands intermediate in relation to other members in the genus in its sclerotestal elaboration, which is assumed to be reflected in the size of the crown and mieropylar beak.