The 5'-terminal sequence of TMV RNA. Question on the polymorphism found in vulgare strain

The complete nucleotide sequence of TMV RNA (common strain) reported in [Proc. Natl. Acad. Sci. USA (1982) 79, 5818] its 5'-end to be represented by two variants which differed in length. We have tested that result and sequenced the 5'-terminal regions of two strains of TMV RNA (common strain OM and tomato strain L) using cloned cDNA copies. The results showed that the 5'-terminal region of the TMV genome is not polymorphic and that one of the two variants cited above represents a tomato strain but not the common strain.     

Subclones of normal clonal prolactin cells of the rat.

We recently established a clone (2B8) of normal rat prolactin cells that secretes only prolactin into the medium. When grown in the presence of thyrotrophin-releasing hormone (TRH), estradiol (E2) or arginine vasotocin (AVT), the cells show increased production of prolactin. Subclones of single cell origin were developed from 2B8 cells exposed for 1 week to TRH, E2 or TRH plus E2. These subclones differ in their response to TRH, E2 or AVT and therefore may possess different receptors for these hormones.     

Relationship between transpiration and amino acid accumulation in Brassica leaf discs treated with cytokinins and fusicoccin

Both cytokinins and fusicoccin (FC) stimulated the transpirationand the amino acid accumulation in leaf discs of Brassica campestrisvar. komatsuna. Enhancement effects were of the same magnitude.Both the accumulation and the transpiration were similarly inhibitedwhen vaseline was smeared on the leaf surface. Abscisic acid(ABA) also inhibited those cytokinin-induced effects. The accumulationof amino acid-¹⁴C was at the cytokinin- or FC-treated site unlessthe leaf surface was smeared with vaseline. These facts suggestthat cytokinin- or FC-induced amino acid accumulation in leafis caused by the stimulation of transpiration. Present address: ¹ Department of Environmental Studies, Collegeof Integrated Arts & Sciences, Hiroshima University, Higashisenda-machi,Hiroshima 730, Japan. Present address: ² Mitsui Memorial Hospital, 1-Kanda-Izumicho,Chiyoda-ku, Tokyo 101, Japan. (Received May 26, 1977; )     

Factors causing release of ribosomal subunits from isolated nuclei of regenerating rat liver in vitro.

Incubation medium II causes release of ribosomal subunits from isolated prelabeled nuclei of regenerating rat liver in vitro (Sato, T., Ishikawa, K. and Ogato, K. (1976) Biochim. Biophys. Acta 000, 000-000). The effects of individual components of this medium on release of subunits were studied and the following results were obtained. 1. Dialyzed cytosol was effective in causing release of total labeled RNA, but its effect on release of labeled ribosomal subunits was rather lower than that of low molecular yeast RNA. Spermidine inhibited the release of total labeled RNA as well as that of labeled ribosomal subunits. 2. Low molecular yeast RNA was the most effective component for inducing release of labeled ribosomal subunits. Homologous ribosomal RNA was as effective as yeast RNA. Cytoplasmic ribosomes, prepared by washing with solution of high salt concentration, and their subunits were also effective. 3. Transfer RNA was not so effective as yeast RNA and ribosomal RNA and even after heat treatment it had little effect. 4. Among the homopolyribonucleotides tested, polyuridylic acid had a strong effect but polyadenylic acid, polycytidylic acid and polyinosinic acid had no effect. 5. The effects of yeast RNA and polyuridylic acid in causing release of labeled ribosomal subunits were dependent upon their concentrations in the reaction mixture. The characteristics of the factors which cause release of labeled ribosomal subunits in vitro are discussed on the basis of the results.     

RNA synthesis in aphids, Lachnus tropicalis

Aphid cells contain unique RNAs with molecular weights of 1.2 × 10⁶ and 0.6 × 10⁶. These RNAs are larger in amount in the nucleus and labeled rapidly when the insect is injected with [³H] uridine. Seemingly, the 28S and 18S rRNAs are completed at the cost of these RNAs.     

The effects of methylxanthines on catecholamine-stimulated and normal chick embryos.

Dose of theophylline and caffeine which do not produce aortic arch anomalies in embryonic chicks have been shown to potentiate catecholamine-induced aortic arch malformations in that experimental animal. Theophylline (2.1 X 10(-5) mole per milliliter isotonic saline solution) potentiated the effective dose of norepinephrine more than 100 times. The greatest potentiation observed with epinephrine (2.5 X) was induced by 2.6 X 10(-5) mole caffeine. This study also demonstrated that both methylxanthines specifically induce aneurysms of the ascending aorta and complete absence (or nearly complete constriction) of the right ductus arteriosus. The incidences of these types of cardiovascular malformations proved to be dose dependent with theophylline a more potent teratogen than caffeine. The mobilization of calcium and/or cyclic nucleotide phosphodiesterase inhibition by the methylxanthines are suggested as significant actions in the potentiation of catecholamine-induced aortic arch anomalies.     

Re-joining of the 18S fragments dissociated from the 28S ribosomal RNA of insect: a structural role of 5.8S RNA

The 18S RNA fragments, A and B, and 5.8S rRNA were dissociated from 28S rRNA of cultured insect cells, NIAS-Px 58. When a mixture of fragments, A + B, was incubated with ³H-labeled 5.8S RNA under appropriate conditions, a considerable amount of radioactivity was observed with 28S rRNA. It is highly likely that the 5.8S rRNA induced a re-joining of fragment A and B to form the 28S RNA molecule.     

Prostaglandin synthetase activity and hormone responsiveness in normal and SV40 transformed WI-38 fibroblasts.

Prostaglandin (PG) synthetase activity and selective hormone responsiveness were examined in normal and SV40 transformed WI-38 fibroblasts (VA13-2RA). The transformed VA13-2RA cells have significantly reduced rates of PGE1, PGE2, PGF1alpha and PGF2alpha synthesis as compared to the normal WI-38 fibroblast. The transformed cell in contrast to the normal cell hyperresponds to stimulation by L-epinephrine (10 muM) and PGE1 (8.5 muM) but is unresponsive to bradykinin (BK) as measured by the accumulation of intracellular cyclic AMP. Indomethacin treatment does not significantly alter the PGE1 and L-epinephrine (EPI) responsiveness of the normal WI-38 fibroblast, however it abolishes the BK response in these cells. These results provide further evidence for the dependency of cell activation by bradykinin on the PG synthetase system. No experimental data was found to support the role of PGs as negative regulators of PGE1 and EPI responsiveness in the WI-38 fibroblast. Using the VA13-2RA cells, limited attempts to recover PG synthetase activity comparable to that found in normal WI-38 cells were unsuccessful. The VA13-2RA cell and its normal counterpart represent models for investigating the role of PGs in cell function and the mechanism of BK activation and its effect on cell metabolism.     

Daily rhythms of glycogen synthetase and phosphorylase activities in rat liver: Influences of food and light

In rats fed during the night time (from 8 p.m. to 8 a.m.) the activities of liver glycogen synthetase $\text{I}$ and phosphorylase $\text{a}$ varied rhythmically during a 24 hour period. There was an inverse relationship between their levels; the level of synthetase $\text{I}$ rose to a maximum at around 6 a.m. and that of phosphorylase $\text{a}$ attained the peak value at around 6 p.m. Eye enucleation of rats did not affect significantly the daily rhythms of the enzymes. However, when food was offered only during the day time, the phases of both enzyme rhythms were shifted by about 12 hours. On starvation for 24 hours, the glycogen level was reduced almost to nil, but the daily rhythms of the enzymes were retained. It is thus very likely that the daily variations of the enzyme activities are not merely a passive effect of food intake, and that food can be a synchronizer or zeitgeber which sets up the characteristic rhythms of glycogen metabolism in the liver.     

Transport of acid phosphatase to lysosomes does not involve passage through the cell surface

In foregoing studies, we reported that LGP107, a major lysosomal membrane glycoprotein in the rat liver, distributes in and circulates continuously throughout the endocytic membrane system (endosomes, lysosomes and plasma membrane), in hepatocytes (1,2). In the present study we examined whether acid phosphatase (APase), an enzyme that is transported to lysosomes as a transmembrane protein, passes through the cell surface during intracellular transport, because transport of newly synthesized APase to lysosomes involves the passage of endosomes containing a ligand which is internalized via receptors on the cell surface and is finally dispatched to lysosomes for degradation (3). When localization of APase in rat hepatocytes was investigated by immunoelectron microscopy, APase was found to be localized in lysosomes and endosomes, but not in coated pits on the cell surface, which are positive for LGP107, and from which antibodies for LGP107 are internalized. Further, unlike LGP107, newly synthesized APase was not detected in plasma membranes isolated from livers of rats given [35S]methionine, and when cultured hepatocytes were exposed to 125I-labeled anti APase IgG at 37 degrees C, there was no transfer of the antibody to lysosomes even after 24 h incubation. Therefore, these results indicate that intracellular movement of APase does not involve cell surface passage in rat hepatocytes, and clearly differs from the recent report that human APase is transported to lysosomes via the cell surface in BHK cells transfected with its cDNA (4).