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S Natori

Publications and source records attributed to S Natori.

At least 19 recordsLinked to original sources
PubMed1979

Preferential expression of unique sequences adjacent to middle repetitive sequences in mouse cytoplasmic RNA.

Total single-copy DNA and single-copy DNA contiguous to middle repetitive sequences were isolated from mouse brain by successive hydroxylapatite column chromatographies. These DNAs, termed repeat-contiguous single-copy DNA, were found to constitute 48% of the total single-copy DNA. The saturation hybridization values of these two DNA probes to nuclear RNA and cytoplasmic RNA containing polyA of mouse brain and liver were measured. The saturation hybridization levels of total single-copy DNA to brain and liver nuclear RNA were 13.5% and 8.8%, respectively, and those of repeat-contiguous single-copy DNA to the same RNA samples were 13.3% and 8.5%, respectively. On the contrary, the saturation hybridization levels of single-copy DNA to cytoplasmic RNA containing polyA of brain and liver were 3.8% and 2.0%, respectively, and those of repeat-contiguous single-copy DNA to the same RNA samples were 5.8% and 4.0%, respectively. Similar results were obtained with total cytoplasmic RNA. These results indicate that about half the steady state nuclear RNA is transcribed from repeat-contiguous single-copy DNA, and that cytoplasmic RNA containing polyA is mainly derived from repeat-contiguous single-copy DNA.

Animals↗
PubMed1979

Purification and preparation of antibody to RNA polymerase II stimulatory factors from Ehrlich ascites tumor cells.

An improved method was developed for purification of the protein termed S-II that specifically stimulates RNA polymerase II of Ehrlich ascites tumor cells. The specific activity of the final preparation was 400 000 units/mg of protein, which is about 30-fold higher than that of the previous preparation [Sekimizu, K., et al. (1976) Biochemistry 15, 5064]. The final preparation gave a single band on both sodium dodecyl sulfate and nondenaturing gel electrophoresis, and the protein extracted from the band on nondenaturing gel had stimulatory activity. S-II is a basic protein with a molecular weight of 40 500. The fundamental characteristics of S-II determined with the previous preparation were confirmed with completely purified S-II. A specific antibody to S-II was prepared. This antibody inhibited only the stimulatory activity of S-II and did not affect the activity of RNA polymerase II itself. Thus, S-II is probably not a component of the multimeric proteins of RNA polymerase II.

Animals↗
PubMed1979

The production of chaetoglobosins, sterigmatocystin, O-methylsterigmatocystin, and chaetocin by Chaetomium spp. and related fungi.

Production of mycotoxins by Chaetomium spp. and related fungi on rice culture was examined by a combination of cytotoxicity tests using HeLa cells and thin-layer chromatography. Three species, C. mollipilium, C. rectum, and C. subaffine, as well as C. cochliodes and C. globosum, were proved to produce chaetoglobosins. From cultures of four strains of Chaetomium sp., assigned to C. thielavioideum, and one strain of Farrowia sp., chaetocin, sterigmatocystin, and O-methylsterigmatocystin were isolated. Morphological characteristics of the producers of sterigmatocystins are described.

Ascomycota↗
PubMed1979

Inhibitory effects of nucleoside triphosphates on nucleolar RNA synthesis.

Studies on the effects of substrates on RNA polymerase I [EC 2.7.7.6] in vitro showed that nucleolar RNA synthesis was inhibited by an excess of substrate nucleoside triphosphates in the presence of Mg2+. GTP and UTP were more inhibitory than CTP and ATP. These compounds specfically inhibited nucleolar RNA synthesis and a concentration of GTP that strongly inhibited nucleolar RNA synthesis did not inhibit RNA synthesis by partially purified RNA polymerase I. The inhibition of nucleolar RNA synthesis disappeared at pH 9.0 without any change in the apparent Km for GTP or the Vmax of RNA synthesis.

Adenosine Triphosphate↗
PubMed1978

Analysis of RNA synthesized in isolated nuclei of Ehrlich ascites tumor cells.

The molecular size and poly-A content of RNA synthesized in isolated nuclei of Ehrlich ascites tumor cells were measured. KCl was found to be essential for synthesis of high molecular weight RNA: when 0.4 M KCl was added to the reaction mixture, the average molecular size of the RNA formed was 14S; without KCl the average molecular size was 5S. A significant amount of poly-A sequences was found in RNA synthesized in the presence of alpha-amanitin, suggesting that RNA polymerase I and/or III may synthesized some RNA containing poly-A in isolated nuclei.

Amanitins↗
PubMed1978

Induced synthesis of immunoglobulin messenger RNA accompanies induction of immunoglobulin production in cultured mouse spleen cells.

Immunoglobulin kappa type light chain mRNA (Lkappa mRNA) accumulated in parallel with secretion of immunoglobulin M in cultured mouse spleen cells activated by lipopolysaccharide. Actinomycin D suppressed the accumulation of kappa chain mRNA completely without affecting the degradation rate of kappa chain mRNA. The half life of kappa chain mRNA was about 9 h. Available evidence indicates that lipopolysaccharide stimulates de novo synthesis of kappa chain mRNA. The accumulation of kappa chain mRNA was markedly suppressed by inhibitors of DNA or protein synthesis such as hydroxyurea, cytosine arabinoside and cycloheximide.

Animals↗
PubMed1978

Acute toxic effects of chaetoglobosin A, a new cytochalasan compound produced by Chaetomium globosum, on mice and rats.

A new cytochalasan compound, chaetoglobosin A produced by Chaetomium globosum, was studied for its toxicity to animals. By subcutaneous injection, 2 mg/kg body weight of chaetoglobosin A killed young Wistar rats acutely, and in the mouse of DDD strain, LD50 values of chaetoglobosin A were estimated 6.5 and 17.8 mg/kg for male and female, respectively. By oral administration, 400 mg/kg of chaetoglobosin A caused little adverse effect on mice and rats. Pathological examination of the mice, injected subcutaneously with 5 mg/kg of the toxin, revealed marked edema at the injection site which appeared in several hours after injection and subsided in a week. In other tissues necrosis of the thymus and spleen and degeneration of the spermatocytes in the testicles were noticeable. With characteristic cytotoxic effects like cytochalasin B, chaetoglobosin A is an interesting mycotoxin, although it may be of little significance as a food- or feed-borne toxin.

Animals↗
PubMed1978

Toxic effects of rice culture of Aspergillus candidus and its metabolite, xanthoascin, on Japanese quails.

Laying Japanese quails were fed on diet of 1:1 mixture of basal diet and rice cultures of 2 strains of Aspergillus candidus. During 20 days of feeding, egg production was significantly reduced in these groups compared with the birds fed unmolded rice. The liver of the quails sacrificed at 20 days showed fatty degeneration of hepatic cells. Following withdrawal of the moldy rice, rate of egg production recovered in 5 days. The suppressive effect of egg production seems to be secondary to hepatic injury. In the other experiment, xanthoascin, a purified mycotoxin of A. candidus, was given subcutaneously between 2 to 5 mg/g body weight. In all groups mortality was about 80%. Survivors produced no eggs 10 days following the injection. The liver of quails that died in 1 to 4 days showed focal necrosis, fine droplet fatty degeneration and bile thrombosis of bile ductules. The features are similar to those observed previously in mice and rats, but the quail is far more sensitive to injected xanthoascin than rodents.

Animals↗