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H Danbara

Publications and source records attributed to H Danbara.

At least 55 records · Page 3Linked to original sources
PubMed1991

Chemical structure of glycosphingolipids isolated from Sphingomonas paucimobilis.

Two novel glycosphingolipids were isolated from Sphingomonas paucimobilis and their structures were completely elucidated. The glycosyl portion of the glycosphingolipid consists of an alpha-D-Manp-[1----2)-alpha-D-Galp-(1----6)-alpha-D-GlcpN-(1 ----4)-alpha-D- GlcpA-R tetrasaccharide. The hydrophobic residue R was found to be heterogeneous with respect to the dihydrosphingosine residue. Erythro-1,3-dihydroxy-2-amino-octadecane and erythro-1,3-dihydroxy-2-amino-cis-13,14-methyleneoctadecane were identified in comparable amounts. Both dihydrosphingosine derivatives were quantitatively substituted by an (S)-2-hydroxymyristic acid in amide linkage.

Glycosphingolipids↗
PubMed1991

The epitope structure in lipopolysaccharide recognized by the serotype 2-specific monoclonal antibody of Actinobacillus pleuropneumoniae.

The polysaccharide structure recognized by a monoclonal antibody specific to serotype 2 lipopolysaccharide of Actinobacillus pleuropneumoniae was investigated using an enzyme-linked immunosorbent assay inhibition test. Lipopolysaccharide obtained from serotype 2, strain SH-15, was hydrolysed with acetic acid to liberate the polysaccharide portion, and the polysaccharide mixture was fractionated by gel filtration. The longer polysaccharide, composed of O-antigenic polysaccharide and core, fully inhibited the binding of monoclonal antibodies to a whole cell antigen of strain SH-15, whereas the core oligosaccharide without O-polysaccharide did not. No inhibition was observed with the monosaccharides which were the components of serotype 2 LPS. Enzyme-linked immunosorbent assay inhibition ability of O-polysaccharide was completely lost only by O-deacetylation. These results demonstrate that the epitope of the serotype-specific monoclonal antibody resided in O-polysaccharide of LPS and that the O-acetyl group was essential for the epitope structure.

Acetylation↗
PubMed1991

Positive regulator for the expression of Mba protein of the virulence plasmid, pKDSC50, of Salmonella choleraesuis.

A positive regulator was identified within a 2.3 kb fragment of the 6.4 kb mouse bacteremia region (mba region) of the virulence pKDSC50 plasmid of Salmonella choleraesuis. Sodium dodecyl sulphate polyacrylamide gel electrophoresis showed that Escherichia coli K-12 carrying the recombinant plasmids of the 2.3 kb fragment produced Mba1 protein with a molecular mass of 32 kDa. The recombinant plasmids carrying a 4.1 kb fragment, the other part of 6.4 kb region, produced Mba2 (32 kDa), Mba3 (70 kDa) and Mba4 (29 kDa) proteins. All three proteins were expressed by using the lacZ promoter under isopropyl thiogalactoside induction. In contrast to this, Mba3 protein was overexpressed independently of the lacZ promoter when the 2.3 kb fragment coexisted either in cis or trans. These results suggest that Mba1 is a trans-acting positive regulator for the expression of the Mba3 protein of mba region of pKDSC50.

Animals↗
PubMed1991

A pathological study on the virulence of Salmonella choleraesuis associated with 50-kilobase plasmid in mice.

The virulence of Salmonella choleraesuis associated with 50-kilobase plasmid was assessed by the pathology produced in mice. The strains used in this study were plasmid-contained RF-1, plasmid-cured 31N-1 and plasmid-reintroduced 31N-1-T. Mice were intraperitoneally inoculated with sublethal doses of these bacteria and chronologically necropsied. Pathologically, the plasmid-positive (P+) cases were distinctly different from the plasmid-negative (P-) ones, especially in the peritoneal fluids and peritoneum. The P+ cases were characterized by extensive, granulomatous peritoneal lesions composed of abundant macrophages frequently with neutrophils, sero-fibrinous exudates and vasculitis and the bacterial antigens were detected in such sites. By contrast, the peritonea in the P- cases were mildly involved and had scattered granulomas. The bacterial antigens were hardly visible in all tissues examined. It is suggested that spread preparations of the mesentery may be a useful tool for observing the distribution of peritoneal lesions.

Animals↗
PubMed1990

Identification and mapping of mba regions of the Salmonella choleraesuis virulence plasmid pKDSC50 responsible for mouse bacteremia.

A restriction cleavage map was constructed for pKDSC50, the 50 kb virulence plasmid of Salmonella choleraesuis. Using Tn1 transposon-insertion mutagenesis, we obtained 19 mutant strains of S. choleraesuis with a diminished ability to cause bacteremia in the mouse. pKDSC50::Tn1 DNA of the mutant strains was extracted and introduced into a pKDSC50-cured S. choleraesuis strain. Nine of the 19 transformants showed the diminished ability to cause mouse bacteremia. Tn1-insertion of the nine mutant strains was clustered within a 6.2 kb segment of pKDSC50, demonstrating that this region was necessary for conferring ability to cause mouse bacteremia (Mba) on the host organism. Two regions, mba-1 and mba-2, were identified within the 6.2 kb fragment. In E. coli minicells, the cloned fragments containing the mba region expressed at least three proteins with apparent molecular weights of 29,000, 32,000 and 32,000.

Animals↗
PubMed1990

Transposon insertion mutagenesis of a genetic region encoding serum resistance in an 80 kb plasmid of Salmonella dublin.

Using transposon insertion mutagenesis with Tn1 or Tn5, we obtained Salmonella dublin mutant strains that showed either diminished serum resistance (five mutants) or diminished mouse lethality (two mutants). Detailed restriction cleavage analysis to determine the single sites of transposon insertion in an 80 kb plasmid (pTE800) indicated that a region for serum resistance was located within a 3.0 kb region of the SalI cleavage fragment 5 and the HindIII fragment 2, while the region for mouse lethality was within a 6.0 kb region of the SalI fragment 2 and the HindIII fragment 1. When the Tn1-containing SalI fragment 5 was reconverted, by homologous recombination, to the original SalI fragment 5 (9.6 kb), serum resistance was recovered to the same level as that of a parent strain 52401. Moreover, the change in the serum resistance correlated with changes in the neutral sugar composition of the LPS. The mutation in the plasmid in strain TE4-55 that gave diminished mouse lethality was also reversed by recombination with the cloned SalI fragment 2 (15.0 kb), with concomitant recovery of mouse lethality. These results indicate that the genetic region for serum resistance is different from that for mouse lethality, and that the gene for serum resistance is closely involved with the expression of the neutral sugar composition of the LPS of S. dublin.

Animals↗
PubMed1990

Trivalent heat-labile- and heat-stable-enterotoxin probe conjugated with horseradish peroxidase for detection of enterotoxigenic Escherichia coli by hybridization.

A 1,268-bp polynucleotide probe for heat-labile and heat-stable enterotoxins (LTh, STIa, STIb) was conjugated with horseradish peroxidase (HRP). The HRP-conjugated trivalent probe was applied to the detection of enterotoxigenic Escherichia coli (ETEC) by colony and stool hybridizations. The binding of the probe to its targets was assayed by the addition of HRP substrates hydrogen peroxide and luminol in the presence of an enhancer, and the chemiluminescence was recorded by exposure to X-ray film. Slot blot hybridization demonstrated that the HRP-conjugated trivalent probe specifically hybridized with the DNA isolated from ETEC strains. The trivalent probe also specifically identified bacterial colonies of ETEC that produced LTh, STIa, STIb, LTh-STIa, or LTh-STIb. Treatment of targets with sodium dodecyl sulfate and proteinase K remarkably reduced nonspecific hybridization to DNAs of non-ETEC strains. Furthermore, this probe was able to detect stool specimens seeded with 10(2) original ETEC cells per 5 mg of feces. These results suggest that the HRP-conjugated trivalent probe is a candidate for use in the clinical laboratory to detect ETEC.

Bacterial Toxins↗
PubMed1990

Serotyping of O and pilus antigens of Escherichia coli strains isolated from chickens with coli-septicemia.

One hundred and fifty one Escherichia coli strains were isolated from broiler chickens with coli-septicemia in Aichi (63 strains), Shizuoka (58 strains), and Kagoshima (30 strains) prefectures from 1980 to 1987, and their O and pilus antigens were serologically typed. One hundred and twenty five strains (82.8%) were typed into 23 O serogroups, and twenty six strains (17.2%) remained untypable. The predominant O serogroups were O2 (35 strains, 23.2%) and O78 (24 strains, 15.9%). Distribution of O serogroup was different, depending on prefectures where they are isolated. In total, 109 strains (72.2%) possessed Type 1 and/or Fmsha pili (Type 1; 41 strains, Fmsha; 22 strains, and Type 1 and Fmsha; 46 strains), and 42 strains (27.2%) were non-piliated. All the strains lacked K88, K99, 987P, F41, and Att25 pili. The ratios of piliated strains to non-piliated ones were almost the same among the three prefectures. Strains possessing Type 1 pili showed variety of O antigens, but most of the strains with Fmsha pili belonged to O2 serogroup.

Animals↗
PubMed1990

Drug resistance plasmids of Actinobacillus (Haemophilus) pleuropneumoniae serotype 2 strains isolated from swine.

Drug resistance plasmids were detected in two drug resistant strains of Actinobacillus (Haemophilus) pleuropneumoniae serotype 2 isolated in Japan. One strain, Hpn25, was resistant to ampicillin, kanamycin, streptomycin and sulfonamides, and harbored two plasmids with a molecular size of 3.7 and 4.1 kilobases (kb). The other strain, Hpn18, which was resistant to streptomycin, tetracycline, and chloramphenicol, harbored three plasmids with a molecular size of 2.2, 12, and 35 kb. The resistance of Hpn 25 to streptomycin and sulfonamides is mediated by a 4.1 kb plasmid and that of Hpn 18 to streptomycin and chloramphenicol by one or more of the 2.2, 12, and 35 kb plasmids.

Actinobacillus↗
PubMed1989

Lipopolysaccharide alteration mediated by the virulence plasmid of Salmonella.

Lipopolysaccharide (LPS) of Salmonella dublin, S. enteritidis, S. typhimurium, S. choleraesuis and their derivative strains was analysed to investigate the correlation between LPS and virulence plasmid of Salmonella. All wild-type strains had smooth type LPS, i.e. LPS with long O-specific polysaccharide. The virulence plasmid-cured strain of S. dublin, C524, exhibited a shorter O-specific chain than its parent strain, 5240. No distinct ladder bands were observed at the high molecular weight region on the SDS-PAGE gel for C524 LPS. By chemical analysis the number of O-repeating unit of C524 LPS was shown to be approximately one. The chain length of O-specific polysaccharide was restored by reintroduction of the virulence plasmid. The alteration of LPS by curing and reintroduction of the virulence plasmid was not observed when other wild-type strains of S. dublin were used. In the case of S. enteritidis, S. typhimurium, and S. choleraesuis, alteration of neither chemical composition nor electrophoretical profile of LPS was detected by curing and reintroduction of the virulence plasmids. Those results suggest that certain factor for regulation of the chain length of O-specific polysaccharide is encoded on the virulence plasmid of S. dublin.

Lipopolysaccharides↗
PubMed1989

Antibiotic susceptibility of serotype 2 and 5 strains of Actinobacillus (Haemophilus) pleuropneumoniae isolated from swine from 1974 to 1986.

Antibiotic susceptibility of 129 isolates of Actinobacillus (Haemophilus) pleuropneumoniae was examined. All the strains were isolated in 1974 to 1986 from the nasal cavities of swine housed on 35 farms in 11 prefectures of Japan. All 28 strains of serotype 2 isolated before 1984 were susceptible to 10 antibiotics used. In contrast, more than one-half of 79 strains of serotype 2 isolated in 1985 and 1986 were resistant to aminoglycosides, tetracycline, tylosin and carbadox, and most of them showed multiple drug resistance. All the 22 strains of serotype 5 were isolated only in 1985 and 1986, and almost all the isolates were susceptible to the antibiotics used in this study. Distribution of minimal inhibitory concentration of serotype 2 strains were bimodal to aminoglycosides, tetracycline, or tylosin. The present results showed that the number of antibiotic resistant strains of A. pleuropneumoniae has increased recently in Japan.

Actinobacillus↗
PubMed1988

Evidence of correlation between 50-kilobase plasmid of Salmonella choleraesuis and its virulence.

A plasmid of 50 kilobases (kb) was found in all six strains of Salmonella choleraesuis studied, originally isolated from septicemic swine or man. A derivative cured of the 50 kb plasmid was isolated after treatment with novobiocin, and its virulence compared to that of the parent by intraperitoneal injection into mice. The lethality of the parent strain was found higher than that of the cured strain. With a sublethal number of cells of the parent strain injected, the spleen, liver and lymph nodes in various sites were markedly enlarged, and the bacteria were isolated from the heart blood. In contrast to this, neither enlargement of the organs nor recovery of organisms was observed with the cured strain. The Tn1-tagged 50 kb plasmid was next introduced by transformation into the cured strain. The virulence of the plasmid-reintroduced strain was higher than that of the cured strain, and in fact identical to that of the parent. We conclude that the 50 kb plasmid of S. choleraesuis is closely related with the mouse virulence of the organism.

Animals↗
PubMed1988

Plasmid-mediated serum resistance and alterations in the composition of lipopolysaccharides in Salmonella dublin.

Survival rates of Salmonella dublin in rabbit serum after culture for 1 h at 37 degrees C were compared between a wild-type strain (5240) carrying a 50 MDa plasmid, a plasmid-cured strain (C524), and a cured strain containing the 50 MDa plasmid tagged with Tn1 (5241). Strain C524 was more susceptible to the bactericidal activity of normal serum than its parent strain 5240 (percentage survival less than 1% and 52.5 +/- 9.2%, respectively). On the other hand, the percentage survival of strain 5241 was significantly increased (90.4 +/- 4.0%), indicating that the reintroduction of the plasmid into the cured strain restored the serum resistance. Moreover, this change in the serum resistance properties correlated with changes in the neutral sugar composition of the lipopolysaccharides (LPS) of these strains, suggesting that the 50 MDa plasmid is necessary for O-side chain expression in the LPS of S. dublin.

Animals↗