Biomedical subjects

S Natori

Publications and source records attributed to S Natori.

At least 289 records · Page 16Linked to original sources

PubMed1985

Comparison of binding proteins on the surface of murine tumor cells for two lectins active in the lectin-dependent macrophage-mediated cytotoxic reaction.

The binding proteins for Sarcophaga lectin and wheat germ agglutinin on the surface of Ehrlich ascites tumor cells were compared. Studies with antibody against the binding protein for Sarcophaga lectin showed that these two binding proteins are different. Since these two lectins are both active in the lectin-dependent macrophage-mediated cytotoxic reaction with Ehrlich ascites tumor cells as target cells, there must be multiple proteins on the surface of target cells that can trigger cytolytic reaction in response to different lectins in the presence of macrophages.

Animals↗

PubMed1984

Identification of storage protein receptor and its precursor in the fat body membrane of Sarcophaga peregrina.

A previous paper (Ueno, K., Ohsawa, F., and Natori, S. (1983) J. Biol. Chem. 258, 12210-12214) showed that a storage protein receptor is present in membranes of the pupal fat body of Sarcophaga peregrina, whereas membranes of the larval fat body contain a cryptic receptor, and that 20-hydroxyecdysone is essential for activation of the cryptic receptor to bind and incorporate the storage protein. The present paper reports that the storage protein receptor is a membrane protein of the pupal fat body with a molecular mass of 120 kilodaltons, and that the cryptic receptor present in membranes of the larval fat body is a precursor of the active receptor with a molecular mass of 125 kilodaltons. It is suggested that when 20-hydroxyecdysone is secreted, it activates the process of conversion of the 125-kDa protein to the 120-kDa protein. Concomitant protein synthesis was not apparently necessary for activation of the storage protein receptor, suggesting that the target of 20-hydroxyecdysone in this case is the fat body membrane.

Adipose Tissue↗

PubMed1984

Induction of human gamma interferon by Sarcophaga peregrina humoral lectin.

Humoral lectin isolated from the hemolymph of injured Sarcophaga peregrina (flesh-fly) larvae was found to activate human peripheral blood cells to produce interferon activity. This interferon was inactivated by dialysis against a solution of pH 2.0 and by heat treatment at 56 degrees C for 30 min, indicating that it was a gamma interferon. The role of this lectin in the defence mechanism is discussed from the viewpoint of comparative immunology.

Animals↗

PubMed1984

Induction of TNF-like factor by murine macrophage-like cell line J774.1 on treatment with Sarcophaga lectin.

On stimulation with Sarcophaga lectin, the mouse macrophage-like cell line J774.1 secreted a factor like the tumor necrosis factor (TNF) into the culture medium. This factor was a protein with a molecular weight of 40000-45000, and was cytotoxic to L-929 cells, but not to normal embryonic fibroblasts. This factor was effective on both the ascites form and solid form of sarcoma 180 transplanted into ICR mice.

Animals↗

PubMed1984

A phenylalanine for serine substitution in the beta subunit of Escherichia coli F1-ATPase affects dependence of its activity on divalent cations.

A mutant (KF11) of Escherichia coli H+-translocating ATPase (F1-F0) has a single point mutation in the beta subunit of F1 that has lost 90% of its Mg2+-dependent ATPase activity (Kanazawa, H., Horiuchi, Y., Takagi, M., Ishino, Y., and Futai, M. (1980) J. Biochem. (Tokyo) 88, 695-703). The mutation was mapped at about the 500th nucleotide residue from the 5' end of the beta subunit gene by a genetic recombination test on the physical map of the cistron coding for the beta subunit. The mutant allele of KF11 (uncD11) was cloned on a hybrid plasmid (pKF11) via DNA isolated from a lambda uncD11 transducing phage. Restriction fragments of pKF11 containing the estimated mutation site were subjected to polyacrylamide gel electrophoresis under conditions where strands were separated into single strands. The two strands of a DNA segment, which was shown to carry an altered base, showed anomalous migration compared with those from the wild-type fragment. The results confirmed the result of mapping of the altered site by genetic tests. On the basis of these results, the nucleotide sequence of the mutated gene was determined, and a single base change of the 524th cytosine to thymine resulting in a phenylalanine for serine substitution at residue 174 of the beta subunit was found. This result, together with results on the altered properties of F1 from KF11 reported previously, indicates that residue 174 is essential for the Mg2+-dependent ATPase activity of F1 but not for the Ca2+-dependent ATPase activity.

Amino Acid Sequence↗

PubMed1984

Mode of action of a bactericidal protein induced in the haemolymph of Sarcophaga peregrina (flesh-fly) larvae.

The mode of action of a bactericidal protein (sarcotoxin I) purified from the haemolymph of Sarcophaga peregrina (flesh-fly) larvae was studied, focusing attention on its effect on the function of the membrane of Escherichia coli. Sarcotoxin I almost completely blocked the uptakes of tetraphenylphosphonium ion and proline, which are known to be driven by a membrane potential, indicating that this protein disrupts the membrane potential of bacteria.

Animals↗

PubMed1984

Effect of the DNA-binding domain of poly(ADP-ribose)synthetase on accurate transcription initiation in a HeLa cell lysate.

The effect of papain-digested fragments of poly(ADP-ribose)synthetase on accurate transcription initiation by RNA polymerase II was studied using a HeLa cell lysate. It was found that the DNA-binding domain of the enzyme, like the intact enzyme, preferentially suppressed random transcription initiation, whereas the automodification domain had no effect on transcription.

DNA↗

PubMed1984

Multi-gene structure of the storage protein genes of Sarcophaga peregrina.

Three recombinant phages containing chromosomal segments of Sarcophaga peregrina encoding storage protein were isolated. These clones were found to contain sequences hybridized with the messenger RNA of 75,000 Mr protein, a monomer of storage protein. From restriction analysis it was found that message-homologous regions are not identical, and thus are different genes with similar sequences. From the analysis of these clones it was concluded that the storage protein gene belongs to a multi-gene family.

Animals↗

PubMed1984

Analysis of the stimulatory factor of RNA polymerase II in the initiation and elongation complex.

The interaction between RNA polymerase II and its specific stimulatory factor S-II was studied using each component purified to near homogeneity. It was found that RNA polymerase II and S-II form a complex in the absence of DNA and nucleoside triphosphates, although their interaction was weak. This interaction became stable in the presence of a template and substrates, and a stoichiometric amount of S-II was found to remain in the transcription machinery during RNA chain elongation.

Animals↗

PubMed1984

Modulation of nonglobin mRNA levels in erythropoiesis.

During erythropoiesis, the decrease of complexity of a RNA population is an important process as is globin mRNA accumulation. To determine the sequential control process of gene expression, many genomic clones which express in mouse reticulocytes were obtained and used for the titration of each mRNA level in the different stages of erythroid cells. The level of mRNAs of rt-clones decreases depending on the maturation of erythroid cells, and the coordinated and sequential control of this level is likely to be one of the factors affecting this process.

Animals↗

PubMed1984

Identification of hemagglutinating protein and bactericidal activity in the hemolymph of adult Sarcophaga peregrina on injury of the body wall.

When the body wall of adult Sarcophaga peregrina (flesh-fly) was injured with a hypodermic needle, hemagglutinating activity and antibacterial activity were induced in the hemolymph simultaneously. The hemagglutinating activity was shown to be due to the same lectin that was found previously in the hemolymph of injured larvae. Thus, larval and adult Sarcophaga respond in the same way to injury of the body wall.

Animals↗

PubMed1984

Sarcophagine (beta-alanyl-L-tyrosine) synthesis in the fat body of Sarcophaga peregrina larvae.

The fat body of Sarcophaga peregrina larvae was found to have activity for synthesis of sarcophagine (beta-alanyl-L-tyrosine). This activity was due to a soluble enzyme (sarcophagine synthetase) that requires Mg2+ and ATP as cofactors. The enzyme activity decreased significantly after puparium formation and no sarcophagine synthesis was detected when fat body from white pupae was incubated in vitro with 3H-beta-alanine. This apparent loss of sarcophagine synthesis was found to be partly due to peptidase, which was induced in the fat body after puparium formation. The activity of sarcophagine synthetase itself in the lysate of pupal fat body, however, was found to be significantly lower than that in the lysate of larval fat body, suggesting the presence of a developmentally regulated mechanism of sarcophagine production.

Adenosine Triphosphate↗

PubMed1984

Accurate transcription initiation in an Ehrlich ascites tumor cell lysate.

An in vitro system for accurate transcription initiation by RNA polymerase II was developed using Ehrlich ascites tumor cells. Truncated DNA containing adenovirus 2 major late promoter was faithfully transcribed in this lysate, although the efficiency of transcription was lower than that in a HeLa cell lysate. Creatinephosphate greatly enhanced accurate transcription in this lysate. The transcriptions of various truncated mouse genes containing promoter regions in this lysate were tested, but the syntheses of run-off products were not clearly detected. Adenovirus 2 major late promoter was utilized more efficiently when integrated into circular plasmid DNA than when integrated into truncated DNA, as shown by S1 nuclease analysis.

Animals↗

PubMed1984

Enhancement of the frequency of initiation by a stimulatory protein of RNA polymerase II.

By use of purified RNA polymerase II, it was demonstrated that S-II, a stimulatory protein of RNA polymerase II, enhanced the frequency of initiation of transcription from discrete sites on the promoter region of the silk fibroin gene integrated in a supercoiled plasmid DNA in the presence of manganese. In the absence of S-II, RNA polymerase II preferentially initiated RNA synthesis from site +25, 25 bases downstream from the cap site. Of these initiation sites, the initiation from site +25 was not affected by S-II, suggesting that site +25 is structurally different from other initiation sites, including the cap site, and that S-II modifies the latter sites to the same structure as that of site +25. Direct interaction between S-II and DNA in the initiation complex was shown by demonstrating a conformational change of S-II on its interaction with DNA; namely, S-II in the initiation complex was as sensitive to chymotryptic digestion as S-II interacting with DNA, whereas free S-II was completely insensitive to chymotryptic digestion.

Animals↗

PubMed1984

Inhibitory effect of sterigmatocystin and 5,6-dimethoxysterigmatocystin on ATP synthesis in mitochondria.

The inhibitory effects of sterigmatocystin, O-methylsterigmatocystin, and 5,6-dimethoxysterigmatocystin on the ATP synthesis system in mitochondria were compared with that of aflatoxin B1, which disturbs the respiratory chain in mitochondria. Sterigmatocystin and 5,6-dimethoxysterigmatocystin were found to uncouple the oxidative phosphorylation process without causing depression of state 3 respiration. O-Methylsterigmatocystin did not exhibit uncoupling activity at the limited concentrations tested (due to its low solubility in an aqueous system). These compounds, as well as aflatoxin B1, elicited neither pseudo-energized nor energized swelling of mitochondria and did not inhibit Ca2+-induced swelling of mitochondria.

Adenosine Triphosphate↗

PubMed1984

Activation of murine macrophage-like cell line J774.1 by Sarcophaga peregrina lectin.

The effect of Sarcophaga lectin on mouse macrophage-like cell line J774.1 was studied. It was found that this lectin induced significant morphological changes and stimulated glucose consumption of J774.1 cells. A similar effect was observed when bacterial lipopolysaccharide was added to the culture medium. However, although cells treated with lipopolysaccharide were not cytotoxic to allogeneic tumor cells, those treated with Sarcophaga lectin were found to acquire cytotoxicity. The physiological significance of Sarcophaga lectin is discussed from the viewpoint of comparative immunology.

Animals↗

PubMed1983

Identification and activation of storage protein receptor of Sarcophaga peregrina fat body by 20-hydroxyecdysone.

Previous work showed that 20-hydroxyecdysone activates the fat body of Sarcophaga peregrina larvae to incorporate storage protein selectively from the hemolymph. In this study, storage protein receptors of the fat body membrane which were induced on pupation or on treatment of larval fat body with 20-hydroxyecdysone in vitro were identified. The binding of storage protein to its receptor required divalent cations, especially Ca2+, and the binding was very sensitive to pH. The storage protein receptor was inactivated when the fat body membrane was treated with trypsin. The storage protein receptor is probably a protein and it may be synthesized de novo or a cryptic form may be converted to the active form when the concentration of 20-hydroxyecdysone in the hemolymph reaches a physiological level.

Adipose Tissue↗

PubMed1983

Purification and characterization of an antibacterial protein from haemolymph of Sarcophaga peregrina (flesh-fly) larvae.

Three antibacterial proteins were induced when the body wall of Sarcophaga peregrina (flesh-fly) larvae was injured with a hypodermic needle. These proteins were separated and one was purified to homogeneity. The molecular weight of the purified protein was 5000 and its amino acid composition was similar to that of cecropins, which are antibacterial proteins in Hyalophora cecropia (cecropia moth) pupae. This protein was found to have bactericidal activity and to be effective at a concentration of 0.1 micrograms/ml against certain Gram-negative and Gram-positive bacteria.

Amino Acids↗