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Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 307 records · Page 17Linked to original sources
PubMed1983

Measurement of Sarcophaga peregrina lectin under various physiological conditions by radioimmunoassay.

Lectin induced in the hemolymph of Sarcophaga peregrina (flesh fly) larvae on injury of the body wall or on pupation was studied further by radioimmunoassay, focusing on the interaction between the lectin and hemocytes. It was found that the amount of lectin on the surface of hemocytes prepared from injured larvae increased with time after injury of the body wall. Radioiodinated lectin could bind to hemocytes prepared from injured larvae more effectively than those from normal larvae, indicating a difference in the affinities to lectin of hemocytes from these two sources. The lectin was found to be synthesized in the fat-body and then secreted into the hemolymph both on injury of the body wall and on pupation. A significant level of lectin was maintained in pupae during the entire pupal stage, but it decreased rapidly before emergence, and no lectin was found in newly emerged flies. Since the lectin greatly activated the activity of mouse bone marrow cells to kill Candida parapsilosis cells, the biological significance of humoral lectin in the defense mechanism was discussed from the ontogenic viewpoint.

Animals↗
PubMed1983

Selective expression of cloned middle-repetitive sequences in nuclear RNA of mouse organs.

Mouse middle-repetitive sequences have been cloned in the bacterial plasmid pBR322. The DNA sequences, expressed only in nuclei, were screened by filter hybridization using nuclear RNA as probes. Several clones were expressed predominantly in the nuclear RNA in certain types of organs. The copy numbers of typical middle-repetitive sequence clones in genomic DNA were analyzed quantitatively and results showed that 10(3)-10(4) copies exist per haploid DNA, indicating that they belong to a relatively abundant class of repeated sequences. Homology within the family of each middle-repetitive sequence ranged from 81% to 94%. The expression of cloned middle-repetitive sequences was analyzed by liquid-phase hybridization with nuclear RNAs from particular organs. The content of transcripts of the middle-repetitive sequence in nuclear RNA of a particular organ was at least 1000 times higher than that in other organs. In steady-state nuclear RNA these transcripts were calculated to amount to 10(2)-10(4) copies per nucleus. Most of these transcripts seem to be retained in the nuclei and do not appear in the cytoplasm.

Animals↗
PubMed1983

Differential expression of two abundant messenger RNAs during development of Sarcophaga peregrina.

Expression of two abundant mRNAs in the fat body of third instar larvae of Sarcophaga peregrina was studied using genomic clones of storage protein and 25K protein as probes. It was found that these two genes were expressed sequentially in the third instar with a 20-hr interval between their expressions. No amplification of genes was detected during larval development, suggesting that the high level of mRNA was due to efficient transcription. The contents of the two mRNAs in third instar larvae were about the same, although the synthesis of storage protein was much more than that of 25K protein.

Adipose Tissue↗
PubMed1983

Mutagenicity of anthraquinones in the Salmonella preincubation test.

The mutagenicities of 15 naturally occurring anthraquinones were examined in Salmonella typhimurium strains TA98, TA100 and TA2637 by the preincubation method. 7 of the 15 compounds tested, i.e., chrysazin, emodin, islandicin, alizarin, chrysophanol, 2-hydroxyanthraquinone and emodic acid, were strong mutagens in strain TA2637 with metabolic activation. All of these compounds contain 1-3 hydroxyl groups, and some also have methyl groups. Cynodontin, an anthraquinone with 4 hydroxyl groups and 1 methyl group, was only slightly mutagenic in strain TA2637. 2-Hydroxyanthraquinone, alizarin, emodin, islandicin and chrysazin were also mutagenic in strain TA100 with S9 mix. All the bisanthraquinones tested, i.e., skyrin, (+)rugulosin, (-)luteoskyrin, (-)rubroskyrin and sennoside A, were non-mutagenic in this test system with or without metabolic activation. Unsubstituted anthraquinone and anthrone were also non-mutagenic. These results show that hydroxyl substituents are necessary for the mutagenicity of anthraquinones, the optimal substitutions being 1-3 hydroxyl groups per molecule. The 4th hydroxyl group, in the compound cynodontin reduces the mutagenicity considerably.

Anthraquinones↗
PubMed1983

Mutagenicity of natural naphthoquinones and benzoquinones in the Salmonella/microsome test.

The mutagenicities of naturally occurring naphthoquinones and benzoquinones were tested by the pre-incubation method with Salmonella typhimurium strains TA98, TA100 and TA2637, which all contain plasmid pKM101. 6 of the 16 naphthoquinones tested, i.e., plumbagin, naphthazarin, 2-hydroxy-naphthoquinone, vitamin K3 (menadione), juglone and 7-methyljuglone, were mutagenic to strain TA2637 with metabolic activation. Except for juglone and 7-methyl-juglone, these compounds also had slight mutagenic effects on strain TA98 with S9 mix. All the mutagenic naphthoquinones contain one or two hydroxyl and/or methyl substituents. The naphthoquinone mompain, which has four hydroxyl groups, was not mutagenic. Unsubstituted beta-naphthoquinone, naphthoquinones with a prenyl side chain and all bi-naphthoquinone derivatives tested were non-mutagenic. None of the 13 benzoquinones examined was mutagenic to any of the strains used with or without metabolic activation. These results show that natural naphthoquinones are mutagenic when they have only one or two hydroxyl and/or methyl substituents.

Animals↗
PubMed1983

Structural organization of the tissue-specific middle repetitive sequence of the mouse genome.

The structural genes closely linked to the particular middle repetitive sequence (MRS) expressed in liver nuclei were cloned from the mouse genomic library. From one-fourth of 3,200 MRS-containing clones, 21 clones were obtained as mRNA coding sequence-linked MRS clones. From examination of the structural organization and specificity of expression of the MRS and the mRNA coding sequence, it was concluded that expressions of the MRS and the structural genes closely linked to the MRS are independently regulated.

Animals↗
PubMed1983

Identification of a protein having hemagglutinating activity in the hemolymph of the silkworm, Bombyx mori.

Hemolymph of Bombyx mori larvae was found to contain activity to agglutinate trypsinized and glutaraldehyde-fixed sheep red blood cells (fixed SRBC). The specific activity of the hemagglutinin changed during development from the fifth instar to the adult with a transient increase just before pupation. This activity was specifically inhibited by glucuronic acid and heparin. The material with hemagglutinating activity was partially purified by gel filtration on Sephacryl S-300. A protein with molecular weight of 260,000 that preferentially binds to fixed SRBC was identified using radioiodinated hemagglutinin. Antibody raised against this protein specifically inhibited the activity of partially purified hemagglutinin, indicating that this protein is essential for hemagglutination.

Animals↗
PubMed1983

Identification of subunits of RNA polymerase II from Ehrlich ascites tumor cells.

A procedure was developed for large scale purification of RNA polymerase II from Ehrlich ascites tumor cells. About 2 mg of purified enzyme was obtained from 800 g of wet cells. Ten subunits were identified which behaved corresponding to the enzyme activity both on DEAE-Sephadex chromatography and on glycerol density gradient centrifugation. Analysis of tryptic peptides of each subunit showed that these subunits were independent proteins and not structurally related to each other.

Animals↗
PubMed1983

Identification of the DNA binding subunit of RNA polymerase II from Ehrlich ascites tumor cells.

The DNA binding subunits of RNA polymerase II from Ehrlich ascites tumor cells were investigated in the following three ways. (1) RNA polymerase II was dissociated in urea and the binding of the dissociated subunits to DNA was investigated. (2) The RNA polymerase II: DNA complex was dissociated progressively with various concentrations of urea, and the subunits firmly attached to DNA were investigated. (3) RNA polymerase II was dissociated into subunits in a SDS-polyacrylamide gel containing urea and blotted onto a nitrocellulose filter. The filter was then incubated with 32P-nick-translated DNA to identify the DNA binding subunits. These procedures all showed that the largest subunit a of RNA polymerase II had strong affinity to DNA. It was found that a portion of subunits b and c could be recovered in DNA fraction when analyzed by procedures (1) and (2), but no significant DNA binding activity was detected when analyzed by procedure (3), suggesting that these subunits have either a much weaker affinity toward DNA compared to a or have affinity to a itself.

Animals↗
PubMed1983

Change in free amino acids and phospholipids in the head of adult Sarcophaga peregrina with age.

The amino acid and phospholipid contents in the head of adult Sarcophaga peregrina (flesh-fly) were measured with age. Only aspartic acid was found to increase significantly with aging. A significant difference was also detected in the fatty acid composition of the phospholipids. Phospholipids isolated from old flies contained more unsaturated fatty acid than young flies, suggesting that the properties of the membrane of head cells change with age. These changes were observed irrespective of sex or rearing conditions. Thus, it is possible that certain metabolic pathways in post-mitotic cells are selectively affected by aging.

Aging↗
PubMed1983

Chemical and toxicological studies on bracken fern, Pteridium aquilinum var. latiusculum. VIII. The inability of bracken extracts containing pterosins to cause cattle bracken poisoning.

Methanol extracts of bracken frond and rhizomes prepared using a metallic extraction vessel, were proved incapable of producing bracken poisoning in calves. Nevertheless, they contained appreciable quantities of pterosins and pterosides. Thus the poisonous principle(s) in bracken responsible for the toxicological effects are not associated with these major sesquiterpenoids of the plant.

Animals↗
PubMed1983

Polymorphonuclear leukocyte-mediated cytolysis induced by animal lectin.

Nine animal lectins, i.e., Sarcophaga peregrina agglutinin, Balanus roseus agglutinin, Aplysia kurodai agglutinin, Balanus balanoides agglutinin, Tetraclita squamosa japonica agglutinin, Misgurnus anguillicaudatus lectin, Asterina pectinifera agglutinin, Helix aspersa agglutinin and Helix pomatia agglutinin, were tested for induction of cytolysis mediated by polymorphonuclear leukocytes. Among them, S. peregrina agglutinin and B. roseus agglutinin lysed murine target cells in co-operation with polymorphonuclear leukocytes (PMNs) from the peritoneal cavity of mice. PMNs can lyse various tumor cells in the presence of S. peregrina agglutinin, although normal spleen cells were also lysed. This lectin-dependent cytolysis by PMNs was inhibited by galactose, a sugar which is specifically recognized by S. peregrina agglutinin. S. peregrina and B. roseus agglutinins were inhibitory to in vivo development of MM46 tumor cells. These results suggest that PMNs can lyse various target cells in the presence of appropriate animal lectins and that some animal lectins participate in tumor rejection.

Acetylgalactosamine↗
PubMed1983

Preferential inhibition of the activity of a stimulatory protein of eukaryotic transcription by platinum (II) complexes.

The effect of platinum(II) complexes on RNA polymerase II was studied. (D-Glucuronato)(1R,2R-cyclohexanediamine)platinum(II) nitrate (II-GHP) preferentially inhibited RNA synthesis in the presence of S-II, an essential component of eukaryotic transcription. When DNA was pretreated with I-GHP, its template activity decreased significantly, especially when assayed in the presence of S-II. The target of platinum(II) complexes is probably DNA. When DNA is modified, regulatory proteins of transcription, such as S-II, seem to lose their function preferentially on such a template, resulting in the inhibition of RNA synthesis.

HeLa Cells↗
PubMed1982

Stimulatory proteins of RNA polymerase II from Ehrlich ascites tumor cells.

Three proteins stimulating RNA polymerase II were purified from Ehrlich ascites tumor cells. Antibody was raised against one of these proteins. Immunofluorescent study revealed that these proteins ubiquitously exist in the nucleoplasm of various eukaryotic cells. This antibody specifically inhibited alpha-amanitin-sensitive RNA synthesis in isolated nuclei of Ehrlich ascites tumor cells and accurate transcription in HeLa cell lysate, indicating that these proteins are essential components of eukaryotic transcription. Two proteins were shown to have the same primary structure except that one of them is phosphorylated.

Animals↗
PubMed1982

Identification of storage-protein messenger RNA of the fleshfly Sarcophaga peregrina.

Storage-protein mRNA was found to be abundant in poly(A)-containing RNA extracted from the fat-body of third-instar larvae of Sarcophaga peregrina (fleshfly). This RNA sedimented at the position of 19S on sucrose-density-gradient centrifugation and the product of its translation in vitro was 75K protein (protein of mol.wt. 75 000), which was precipitated specifically with antibody against storage protein. This product was suggested to contain a signal sequence that is missing in mature storage protein. The poly(A)-containing RNA was also found to contain much of another mRNA coding for 25K protein (protein of mol.wt. 25 000), but the function of this protein is unknown.

Animals↗
PubMed1982

Evidence that stimulatory factor(s) of RNA polymerase II participates in accurate transcription in a HeLa cell lysate.

Antibody raised against S-II, a stimulatory factor of RNA polymerase II from Ehrlich ascites tumor cells, inhibited accurate transcription from adenovirus 2 major late promoter in a HeLa cell lysate. Manganese prevented accurate transcription, but it was essential for expression of the stimulatory activity of S-II. The results indicate that protein(s) cross-reacting immunologically with S-II in a HeLa cell lysate is essential for accurate transcription of truncated DNA, but the stimulatory activity of this factor(s) is not necessary for accurate transcription of truncated DNA.

Animals↗