Increase In Ribonucleic Acid Research Articles

Hypersecretion of submandibular saliva in male mice: Trophic response in small intestine

The submandibular salivary gland of the male mouse and its secretions contain growth-promoting factors that accelerate cell proliferation in vitro and also have effects on the gastrointestinal tract in vivo. We therefore stimulated salivary secretion with isoproterenol for studies of the effects of submandibular saliva on intestinal cell proliferation; only submandibular glands respond to isoproterenol by releasing epidermal growth factors and other growth factors into the saliva. Submandibular sialadenectomized and sham sialadenectomized male mice on pair-feeding schedules were given isoproterenol intraperitonealiy for 1 wk. A 44% increase in ribonucleic acid and a 13% increase in deoxyribonucleic acid were observed in the jejunum of animals with intact submandibular glands (p < 0.001). In the ileum, there was a 26% increase in ribonucleic acid, a 47% increase in deoxyribonucleic acid, and a 28% increase in deoxyribonucleic acid specific activity (p < 0.001). Morphometric measurements showed a 28% increase in villous height (p < 0.001). No differences were found in colonic mucosa. Submandibular saliva increases the nucleic-acid content of mucosal cells and the villous height in the small intestine of male mice, presumably in part because of the growth factors it contains; a systemic metabolic change could also be present.

Influence of amino acid starvation on guanosine 5'-diphosphate 3'-diphosphate basal-level synthesis in Escherichia coli.

We observed that the synthesis of basal-level guanosine 5'-diphosphate 3'-diphosphate (ppGpp) in both relA mutants and relA+ relC strains of Escherichia coli decreased in response to amino acid limitation and that this was accompanied by an increase in ribonucleic acid (RNA) synthesis. Addition of the required amino acid to starved cultures of relaxed bacteria resulted in the resumption of ppGpp synthesis and a concomitant decrease in RNA production. Our results indicate that relA mutants retain a stringent factor-independent ribosomal mechanism for basal-level ppGpp synthesis. They also suggest that in relA+ bacteria, stringent factor-mediated ppGpp synthesis and the production of basal-level ppGpp are mutually exclusive. These findings substantiate the hypothesis that there are two functionally discrete mechanisms for ppGpp synthesis in E. coli. Through these studies we have also obtained new evidence which indicates that ppGpp serves as a modulator of RNA synthesis during balanced growth as well as under conditions of nutritional downshift and starvation.

Ultrastructural changes and biochemical events in basidiospore germination of Schizophyllum commune.

Electron microscopic features and biochemical events were outlined in basidiospore germination of Schizophyllum commune. Normal ultrastructural changes included prominent vacuolization and more abundant endoplasmic reticulum. A lag phase in outgrowth included depletion of cellular reserves of trehalose, mannitol, and arabitol and subsequent increases in ribonucleic acid and protein. Depletion of polyols required exogenous carbon and nitrogen sources and was arrested by protein synthesis antagonists. Outgrowth subsequent to the lag period was accompanied by increased glycogen deposition and alkali-soluble glucan production.

INITIATION AND EARLY DEVELOPMENT OF THE INFLORESCENCE IN PINEAPPLE (ANANAS COMOSUS, ‘SMOOTH CAYENNE') TREATED WITH ACETYLENE

Pineapple plants ‘Smooth Cayenne’ were made to flower by treatment with acetylene. The organization of the vegetative shoot apex is similar to that of many investigated angiosperms in that it shows a zonate pattern, viz., apical zone, peripheral zone, and central‐core rib meristem. The latter zone is weakly developed. Cytological changes at the shoot apex occur as early as 3 days after treatment; these involve nuclear changes and an increase in ribonucleic acid (RNA) in the cytoplasm of cells of the apical zone. A marked increase in the height of the apex occurs by the 9th day; this is preceded by rib meristem activity in the central core. All component parts of the inflorescence are present and in various stages of development by the 21st day at which time vegetative scales and “crown” leaves are initiated.

Increase in ribonucleic acid in the bacterial chromatin body during chloramphenicol treatment.

Increase in ribonucleic acid in the bacterial chromatin body during chloramphenicol treatment.

牛痘ウイルスの感染と免疫に関する研究特に感染局所の変化の分析的研究

In order to study on the relation of vaccinial infection to its immunity which is induced by the former, the changes at the site of rabbit skin inoculated with vaccinia virus were investigated by pathological, immunological and biological means, and the relationship among various factors concerning the infection was pursued. The findings obtained are summarized as follows.1. Vaccinia virus multiplied at the inoculated site of rabbit skin prior to the appearance of the pathologic lesions, reached the maximum with the latter almost at the same time, and then tended to decrease previously to the lesions.2. The complement fixing antigen being produced at the infected site increased parallel with the viral multiplication. It, however, reached the maximum somewhat later and kept its maximum titer a little while longer.3. The antigenicity of the extract of the infected skin related to the degree of the pathologic changes of the skin; namely, in the cases of the weak lesion the antigenicity in vitro was lower than that, in the cases of the intensive one. (See P. 97)4. The proliferation of epithelium accompanied the increase of ribonucleic acid simultaneously.5. The virus neutralizing activity of the extract of the infected skin riled parallel with the increase of rγglobulin in the extract, which was electrophoretically observed as the fraction IV. It seemed therefore that the virus neutralizing antibody was contained in the fraction IV of the extract of the infected skin.

Phage formation in Staphylococcus muscae cultures. XI. The synthesis of ribonucleic acid, desoxyribonucleic acid, and protein in uninfected bacteria.

1. The synthesis of ribonucleic acid, desoxyribomicleic acid, and protein in S. muscae has been studied: (a) during the lag phase, (b) during the early log phase, and (c) while the cells are forming an adaptive enzyme for lactose utilization. 2. During the lag phase there may be a 60 per cent increase in ribonucleic acid and protein and a 50 per cent increase in dry weight without a change in cell count, as determined microscopically, or an increase in turbidity. 3. During this period, the increase in protein closely parallels the increase in ribonucleic acid, in contrast to desoxyribonucleic acid, which begins to be synthesized about 45 minutes after the protein and ribonucleic acid have begun to increase. 4. The RNA N/protein N ratio is proportional to the growth rate of all S. muscae strains studied. 5. While the RNA content per cell during the early log phase depends upon the growth rate, the DNA content per cell is fairly constant irrespective of the growth rate of the cell. 6. Resting cells of S. muscae have approximately the same RNA content per cell irrespective of their prospective growth rate. 7. While the cells are adapting to lactose, during which time there is little or no cellular division, there is never an increase of protein without a simultaneous increase in ribonucleic acid, the RNA N/protein N ratio during these intervals being approximately 0.15. 8. Lactose-adapting cells show a loss of ribonucleic acid. The purines-pyrimidines of the ribonucleic acid can be recovered in the cold 5 per cent trichloroacetic acid fraction, but the ribose component is completely lost from the system. 9. The significance of these results is discussed in relation to the importance of ribonucleic acid for protein synthesis.