| Co-Investigator(Kenkyū-buntansha) |
NAGATA Kumiko HYOGO UNIVERSITY MEDICAL SCHOOL,DEPARTMENT OF MICROBIOLOGY,ASSISTANT PROFESSOR, 講師 (90068502)
TSUDA Masataka OKAYAMA UNIVERSITY,FACULTY OF SCIENCE,DEPARTMENT OF BIOLOGY,ASSOCIATE PROFESSOR, 理学部, 助教授 (90172022)
|
|---|
| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 1994: ¥1,400,000 (Direct Cost: ¥1,400,000)
|
|---|
| Research Abstract |
1.A low-serum medium containing beta-cyclodextrin for cultivation of Helicobacter pylori has been developed. (14)
2.A urease-negative mutant was isolated by allelic exchange mutagenesis. The ureB gene cloned in E.coli was disrupted by the insertion of a Km^R gene, the resulting plasmid was introduced into H.pylori, and a Km^R transformant was obtained which had no urease activity. The wild-type and the mutant strains were indistinguishable from each other in the growth rate, motility, and cytotoxin production. On the other hand, acid resistance in vitro in the presence of urea was abolished in the mutant strain. The colonization ability of these strains was tested by challenging to the nude mouse stomach. After 1 week and 4 weeks the mouse stomach was taken and cut into half. The stomach challenged by the wild-type strain showed inflammation and the strain was recovered. On the other hand, the stomach challenged by the mutant strain did not showed inflammation, and no colonies appeared by cultivation. These results indicated that urease is essentila for colonization in the stomach. (150)
3.By using an isogenic urease-negative mutant, it was proved that the antibacterial activity of lansoprazole against H.pylori is independent from its inhibitory activity on H.pylori urease. (30)
4.A clone containing the whole urease operon was isolated from a H.pylori strain which showed good growth and high competence activity. To investigate the role of a urease-accesory gene, ureI,the gene was dirupted by allelic exchange mutagenesis. The resulting strain showed no urease activity, but produced the urease apoenzyme which was detected by monoclonal antibodies raised against UreA and UreB subunits. (65)
5.H.pylori showed chemotaxis towards urea, urease inhibitor, bicarbonate ion, socium ion, some amino acid. The chemotactic activity was also observed with the urease-negative mutant, indicating that the chemotactic activty of H.pylori towards urea is independent from its urease. (40)
|
