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Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 199 records · Page 11Linked to original sources
PubMed1989

Isolation of the cDNA clone for mouse glycophorin, erythroid-specific membrane protein.

The cDNA clone for a major mouse glycophorin, transmembrane glycoprotein of erythrocytes has been isolated from a mouse spleen erythroblast cDNA library. The primary structure of a major glycophorin indicates that the protein is a single polypeptide chain of 168 amino acids (aa) clearly organized in three domains distinct in the glycophorin of other species. A strong homology of the mouse major glycophorin with human glycophorin A or B, but not with human glycophorin C is observed only in the hydrophobic stretch of 23 nonpolar aa, indicating that the major mouse glycophorin species cloned is similar to human glycophorin A. The glycophorin mRNA is absent in all non-erythroid organs or cell lines examined. The glycophorin mRNA is induced during the differentiation of murine erythroleukemia cells with dimethyl sulfoxide.

Amino Acid Sequence↗
PubMed1989

Nuclear GTP-binding proteins of Swiss 3T3 cells.

The GTP-binding proteins of Swiss 3T3 cell nuclei were analyzed by filter binding assay and UV cross-linking analysis. The results showed the presence of multiple GTP-binding proteins in the nuclei. Scatchard analysis revealed that the Kd value for GTP binding to high-affinity components was 69 nM, that to low-affinity components being 2.7 microM. The GTP-binding activities of some nuclear proteins were found to change significantly in response to the growth conditions of the cells. During culture of cells in medium without serum, the GTP-binding activity of a 140 kDa protein clearly decreased, whereas that of a 40 kDa protein increased.

Animals↗
PubMed1989

Molecular cloning of cDNA for sarcocystatin A and analysis of the expression of the sarcocystatin A gene during development of Sarcophaga peregrina.

Sarcocystatin A is a cysteine proteinase inhibitor purified from the hemolymph of Sarcophaga peregrina larvae [Suzuki, T., & Natori, S. (1985) J. Biol. Chem. 260, 5115-5120]. We isolated a cDNA clone for sarcocystatin A and analyzed the structure and expression of the sarcocystatin A gene. Sarcocystatin A consists of 102 amino acid residues. Significant homology was found between amino acid sequences of sarcocystatin A and other mammalian cystatins, and highly conserved sequences among mammalian cystatins were also found in sarcocystatin A. Using cloned cDNA as a probe, we investigated expression of the sarcocystatin A gene during the development of Sarcophaga. Results showed that this gene was transiently activated in the very early embryonic stage and in the pupal stage, suggesting that sarcocystatin A participates in morphogenesis of larval and adult structures of Sarcophaga.

Amino Acid Sequence↗
PubMed1989

Expression of tumor necrosis factor at a specific developmental stage of mouse embryos.

We investigated the expression of the tumor necrosis factor (TNF) gene during development of mouse embryos, and observed its transient expression on Days 9 and 10 of gestation. We also detected a 25-kDa protein showing immunological cross-reactivity with mouse TNF antibody in an extract of 10-day embryos. These results suggest that TNF plays a role in mammalian ontogenesis.

Animals↗
PubMed1989

Mutagenicity of ptaquiloside, the carcinogen in bracken, and its related illudane-type sesquiterpenes. I. Mutagenicity in Salmonella typhimurium.

Ptaquiloside, a potent carcinogen of an illudane-type sesquiterpene glycoside isolated from Pteridium aquilinum, and its related compounds, hypolosides having the same nucleus isolated from the Pteridaceae, exhibited marked mutagenicity in the modified Ames test with Salmonella typhimurium TA98 and TA100 using a preincubation at pH 8.5. Illudins M and S, sesquiterpenes of the same illudane type from basidiomycetes, also exhibited mutagenicity. The structural requirements for mutagenicity are discussed.

In Vitro Techniques↗
PubMed1989

Mutagenicity of ptaquiloside, the carcinogen in bracken, and its related illudane-type sesquiterpenes. II. Chromosomal aberration tests with cultured mammalian cells.

The chromosomal aberration test using a Chinese hamster lung cell line (CHL) was carried out on ptaquiloside and its related compounds, hypoloside B, hypoloside C, illudin M and illudin S. Ptaquiloside induced chromosomal aberrations at doses as low as 4.5 micrograms/ml (0.0113 mM). The clastogenic effect was pH-dependent. The same activity was observed at a 90-fold higher dose at pH 5.3 in the culture medium compared with the activity at pH 7.4 or pH 8.0. Both hypoloside B and hypoloside C were also clastogenic at almost the same dose level as that of ptaquiloside. Illudin M and illudin S were also potent clastogens and induced aberrations at much lower doses than ptaquiloside. These results suggest that the clastogenic effect is involved in the mechanism of carcinogenic potency of ptaquiloside in animals.

Animals↗
PubMed1989

Restricted degradation of U6 RNA in a nuclear extract of Ehrlich ascites tumor cells.

A new nucleolytic activity that causes restricted digestion of U6 RNA was found in a nuclear extract of Ehrlich ascites tumor cells. This nucleolytic activity specifically degrades U6 RNA in the vicinity of its 3'-end with accumulation of a discrete sized degradation product of RNA of 90-95 nucleotides. Since this degradation product was not digested further by the nuclease under these conditions, this trimming of U6 RNA is supposed to be a biologically meaningful reaction. This nucleolytic activity required Mg2+, and was inhibited by Zn2+ or Ca2+.

Animals↗
PubMed1989

Biosynthesis of chaetochromin A, a bis(naphtho-gamma-pyrone), in Chaetomium spp.

The biosynthesis of chaetochromin A, a metabolite of Chaetomium gracile, has been studied using [13CH3]methionine, sodium [1-13C]acetate, sodium [1,2-13C2]acetate, sodium [1-13C,2,2,2-2H3]acetate, and sodium [1-13C,1,1-18O2]acetate as precursors. The folding pattern of the polyketide chain in chaetochromin A, biosynthesized from sodium [1,2-13C2]acetate as the precursor, was determined to be the same as that of rubrofusarin by carbon-13 nuclear magnetic resonance (13C-NMR) analysis. By using [13CH3]methionine as a precursor, the source of 2-CH3 was determined. When sodium [1-13C,2,2,2-2H3]acetate was fed, a beta-isotope-shifted peak was observed only for carbon 2. In the 13C-NMR spectra of chaetochromin A and of its hexamethyl ether derived from sodium [1-13C,1,1-18O2]acetate, isotope-shifted peaks were observed for carbons 4, 5, 6, 8 and 10a, but not for carbon 2. These results showed that oxygen 1 originated from the same unit of acetate as carbon 10a.

Ascomycota↗
PubMed1989

A mutagenic new iridoid in the water extract of catalpae fructus.

A mutagenic principle in the water extract from Catalpae Fructus (originated from Catalpa ovata G. DON) (Bignoniaceae) was isolated and characterized as a new iridoid named catalpin. The iridoid exhibited mutagenic activity towards Salmonella typhimurium strain TA100 in the presence and absence of rat liver homogenate (S9) mix in Ames' test.

Animals↗
PubMed1989

Growth hormone releasing hormone-sensitive adenylate cyclase activity in growth hormone-producing pituitary adenoma: correlation to the response of plasma growth hormone to growth hormone releasing hormone in patients with acromegaly.

The correlation between response of plasma GH to GHRH and the GHRH-induced stimulation of the intracellular adenylate cyclase (AC) activity in pituitary adenoma cell membranes in acromegalic patients was investigated. Each peak plasma GH level after iv administration of GHRH ranged from 1.1 to 13.8 times the basal level in 13 acromegalic patients. On the other hand, the maximal stimulation of intracellular AC activity (cAMP production) induced by GHRH varied from 1.4 to 6.4 times the control level in each GH-producing pituitary adenoma cell membrane. A significant positive correlation (r = 0.89, P less than 0.005) between plasma GH response to GHRH and intracellular cAMP production stimulated by GHRH was observed in nine of the acromegalic patients. In contrast, the response of plasma GH to GHRH was significantly blunted, despite a fairly large production of intracellular cAMP stimulated by GHRH, in the other four acromegalic patients. These results suggest that GHRH-induced GH release from GH-producing pituitary adenomas of patients with acromegaly may be regulated not only by GHRH receptor-adenylate cyclase system but also modified by several other factors including somatostatin and Sm-C.

Acromegaly↗
PubMed1989

LHRH increases plasma 7B2 concentration in normal human subjects.

We studied the response of plasma 7B2 to LHRH and ovine corticotropin releasing hormone (o-CRH) in healthy young subjects. The plasma 7B2 concentration significantly increased from 78.3 +/- 7.5 (mean +/- SEM) to 102.0 +/- 6.0 ng/L (142.7 +/- 12.7% of the basal value; P less than 0.01) following iv administration of LHRH in seven young subjects. On the other hand, no increase in plasma 7B2 was found after iv administration of o-CRH in six young subjects. These results, together with our previous report of no increase in plasma 7B2 after administration of TRH and GHRH in young subjects, suggest that pituitary 7B2 may be present in gonadotrophs and be released only by LHRH in physiological conditions.

Adrenocorticotropic Hormone↗
PubMed1989

Effect of GRF and somatostatin on 7B2 secretion by rat GH1 cells.

A novel pituitary protein "7B2" was secreted by GH1 cells. The secretion of 7B2 was increased in the presence of human GRF in a dose-responsive manner. In contrast, a somatostatin analog, SMS 201-995, revealed the inhibitory effects on the basal- and GRF-induced secretion of 7B2 at the concentration of 10(-7) M. These findings suggest that 7B2 is a secretory protein of rat GH1 cells under certain conditions.

Adenoma↗
PubMed1988

Purification of three antibacterial proteins from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina.

Three antibacterial proteins were purified from the culture medium of NIH-Sape-4, an embryonic cell line of Sarcophaga peregrina (flesh fly). Sequencing studies showed that two of these proteins belong to the sarcotoxin I family, potent antibacterial proteins purified from the hemolymph of Sarcophaga larvae, whereas the other protein, named sapecin, is a new protein consisting of 40 amino acid residues including 6 cysteine residues. Unlike sarcotoxin I, sapecin preferentially represses the growth of various Gram-positive bacteria. The proteins of the sarcotoxin I family produced by this cell line were found to have carboxyl-terminal glycine, whereas sarcotoxin I in the hemolymph has amidated amino acids. This suggests that the embryonic cells lack an enzyme that cleaves off carboxyl-terminal glycine to form a new amidated carboxyl terminus.

Amino Acid Sequence↗
PubMed1988

Molecular cloning of cDNA for sapecin and unique expression of the sapecin gene during the development of Sarcophaga peregrina.

A cDNA clone for sapecin, an antibacterial protein produced by an embryonic cell line of Sarcophaga peregrina, was isolated and characterized. This clone was found to encode a precursor of sapecin consisting of 94 residues, with sapecin (40 residues) constituting its carboxyl-terminal half. RNA blot hybridization revealed that the gene for the sapecin precursor is activated in the hemocytes of the third instar larvae of Sarcophaga in response to body injury. Thus, sapecin is probably a defense protein synthesized by Sarcophaga to prevent bacterial infection through the damaged body wall. This gene was also found to be activated in the embryonic and early pupal stages, suggesting that sapecin also plays a role in the ontogenetic processes of Sarcophaga.

Amino Acid Sequence↗
PubMed1988

Augmentation and stable expression of a novel transcription factor SII in CD4-positive cells on infection with human immunodeficiency virus type-1 (HIV-1).

We have examined the expression of a novel transcription factor SII in HIV-infected cells. Concomitant with the increasing expression of HIV-1 mRNA, the viability of HIV infected cells dropped and the expression of beta-actin gene also diminished. Concurrently, the expression of SII mRNA was stabilized or augmented. The data presented in this communication suggests that in HIV-1 infected cells, selective transcriptional controls were taking place and that a novel transcriptional factor, SII, plays an essential role in HIV-1 expression leading to cytocidal effects.

Actins↗
PubMed1988

Stimulation of transcription from accurate initiation sites by purified S-II.

The effects of transcription factors S-II and S-II', a phosphorylated form of S-II, on accurate transcription were compared in a reconstituted transcription system greatly depleted of S-II. S-II, but not S-II', stimulated the syntheses of run-off products of various truncated class II genes in this system, suggesting that the activity of this factor is regulated by its phosphorylation and dephosphorylation.

Adenoviruses, Human↗
PubMed1988

Humoral mediator-dependent activation of the Sarcophaga lectin gene.

Sarcophaga lectin is a defence protein synthesized by the fat body and secreted into the hemolymph in response to injury of the body of third instar larvae of Sarcophaga peregrina (flesh-fly). In this paper, we demonstrate that the stimulus of body injury is first transmitted to a certain tissue present in the anterior part of the body, and from there a mediator molecule that interacts directly with fat body cells is secreted into the hemolymph. On interaction with this mediator molecule, the fat body begins to synthesize mRNA for Sarcophaga lectin.

Animals↗