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Biomedical subjects

Y Nishimura

Publications and source records attributed to Y Nishimura.

At least 1,225 records · Page 68Linked to original sources
PubMed1977

On the process of cellular division in Escherichia coli: a mutant of E. coli lacking a murein-lipoprotein.

A mutant of E. coli lacking a specific outer membrane lipoprotein was found. Both the free and the bound form have been lost in this mutant. No material that cross-reacted with antiserum against lipoprotein was detected by the Ouchterlony test. The mutant was defective in producing mRNA active for lipoprotein synthesis. The mutation leading to the loss of lipoprotein synthesis, referred to as lpo, seems to have arisen during production of an F'. The map position of lpo was at 36.5 min on the E. coli K12 map, in the order man, uidA, lpo, aroD, pps. The lpo mutant grew and divided normally and remained susceptible to bacteriophages lambda, phi80, P1, P2, the T series, and f1, f2, and MS2 in its male derivatives. The mutant was hypersensitive to EDTA and cationic dves and somewhat sensitive to detergents. There was considerable leakage of periplasmic enzymes but passive transport of beta-galactoside was unchanged. These physiological characteristics of the mutant suggest that lipoprotein is involved in maintaining the integrity of the outer envelope structure, by bridging the outer membrane and murein, but not in the vital processes of growth and division.

Cell Division↗
PubMed1977

Mutants of Escherichia coli lacking in highly penicillin-sensitive D-alanine carboxypeptidase activity.

Mutants of Escherichia coli lacking in the highly penicillin-sensitive enzyme activities of D-carboxy-peptidase, transpeptidase, and endopeptidase, and with the concomitant absence of penicillin-binding protein 4 of B.G. Spratt and A.B. Pardee [(1975) Nature 254, 516-517] were isolated. The defect of these mutants is ascribed to the lack of an enzyme, D-alanine carboxypeptidase Ib. Genetic mapping studies show the mutation (dacB) to be located at 68 min on the E. coli chromosome map. The dacB mutation results in the simultaneous loss of D-alanine carboxypeptidase and penicillin-binding protein 4. The mutants grew normally under a wide range of growth conditions. We conclude that the enzyme is not a necessary component for normal peptidoglycan biosynthesis in E. coli.

Alanine↗
PubMed1977

Amino acid replacement in a mutant lipoprotein of the Escherichia coli outer membrane.

The primary structure of a mutant lipoprotein of the outer membrane of Escherichia coli was investigated. This mutant was previously described as a mutant that forms a dimer of the lipoprotein by an S-S bridge (H. Suzuki et al., J. Bacteriol. 127:1494-1501, 1976). The amino acid analysis of the mutant lipoprotein revealed that the mutant lipoprotein had an extra cysteine residue, with concomitant loss of an arginine residue. From the analysis of the mutant lipoprotein revealed that the mutant lipoprotein had an extra cysteine residue, with concomitant loss of an arginine residue. From the analysis of tryptic peptides, it was found that the arginine residue at position 57 was replaced with a cysteine residue. The amino terminal structure of the mutant lipoprotein was found to be glycerylcysteine, as in the case of the wild-type lipoprotein. The present results show that the mutation that was previously determined to map at 36.5 min on the E. coli chromosome occurred in the structure gene (lpp) for the lipoprotein. This was further confirmed by the fact that a merodiploid carrying both lpp+ and lpp produces not only the wild-type lipoprotein but also the mutant lipoprotein.

Amino Acids↗
PubMed1977

The use of two V-flaps for secondary correction of the cleft lip nose.

Our new method for correction of the cleft lip nose with moderate deformity consists of shifting a V-shaped flap of alar cartilage and nostril lining medially at the tip of the nose, and shifting the alar base, as another V-flap, medially to the base of the columella. The latter creates a nostril sill.

Child↗
PubMed1977

Enzymatic solubilization of membrane immunoglobulin (M-Ig) from rabbit lymphocytes with phospholipase A2 (PL-A2) and phospholipase C (PL-C).

Enzymatic solubilization of M-Ig from rabbit lymph node cells was investigated using highly purified PL-A2 and PL-C. The combined treatment with PL-A2 (50 I.U./ml) and PL-C (20 I.U./ml) caused optimal solubilization of the membrane components from the 125I-labeled lymphocytes, but the treatment with either enzyme alone did not. The solubilized M-Ig was isolated and characterized as the membrane component which was specifically co-precipitable with homologous antigen-antibody complex. The solubilized M-Ig associated with some other membrane constituents was eluted in a void volume fraction by gelfiltration on a column of Sepharose 6B, and recovered at the interface between 30 and 40% sucrose layers by the density gradient centrifugation. The isolated component could be further separated by SDS-polyacrylamido gel electrophoresis into four radioactive polypeptides with apparent mol wt of 7 approximately 8 X 10(4), 4 approximately 5 X 10(4), 3 approximately 3.5 X 10(4) and 2 approximately 2.5 X 10(4), respectively. The results suggest that the enzymatic solubilization of lymphocyte M-Ig is a useful procedure to investigate further characteristics of M-Ig and their biological function related to the intracellular mechanisms of immune response.

Animals↗
PubMed1976

Novel mutation that causes a structural change in a lipoprotein in the outer membrane of Escherichia coli.

A novel mutation which caused a structural change in a lipoprotein in the outer-membrane has been found in Escherichia coli K-12. The lipoprotein of the wild-type strain is known to have a peculiar amino terminal structure: glycerylcysteine with two fatty acids attached by ester linkages and one fatty acid by an amide linkage. In contrast to the wild-type lipoprotein, the mutant lipoproteins is isolated from the E. coli envelope as a dimer of molecular weight of about 15,000. The dimer can be reduced by mercaptoethanol to the lipoprotein monomer of molecular weight of about 7,500. The monomer has a free thiol group which is susceptible to monoiodacetie mutant lipoprotein is extremely low in comparison with that into the wild-type lipoprotein. These results suggest that the mutant is defective in transferring a glycerol group to the thiol group of the amino terminal cysteine residue of the lipoprotein. The gene responsible for this modification reaction has been located at 36.5 min on the E. coli chromosome.

Bacterial Proteins↗
PubMed1976

Quantitative micro-determination of antibody by inhibition in single radial immunodiffusion.

A modified method of single radial immunodiffusion was devised, providing a quantitating procedure of a small amount of antibody in antiserum. The method consisted of preincubation of the reference antigen with the antiserum, application of the mixture to the antigen well on the reference antibody agar plate, the measurement of the size of the precipitation ring, and comparison of the reduced ring size with that of the reference antigen alone. In this method, it has been found that a quantitative relationship exists between the concentration of antibody in the antiserum and the resulting ring size (-/d2) on the reference antibody agar plate. This method has the advantages that only a very small amount of antibody protein, such as a few micrograms, is required for the titration; and that appropriate antisera, even if they were prepared from different animal species, can most probably be used as the reference antiserum. The applicability of the modified method to the titration of antibody has been verified in this paper with several different antigen-antibody systems.

Antibodies↗