1993 Fiscal Year Final Research Report Summary
Toxic action of Mycrocystis, a causative bacteria for water pollution
| Project/Area Number |
04807030
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
細菌学
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| Research Institution | Jichi Medical School |
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Principal Investigator |
NAKANO Yasunobu Jichi Medical School, Assistant Professor, 医学部, 講師 (70207851)
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| Co-Investigator(Kenkyū-buntansha) |
SAITO Shinji Jichi Medical School, Instructor, 医学部, 助手 (50195989)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Microcystin / Interleukin-6 / Interleukin-10 / Monoclonal antibody / Microcystis aeruginosa / Microcystis |
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| Research Abstract |
Cyanobacterial blooms are a serious problem in many countries, because of the water pollution and causes for deaths of animals drinking the water containing toxic cyanobacterium. The toxicity of water blooms has been mostly associated with Microcystis aeruginosa, whereas heptotoxic cyclic heptapeptides have been found in various Microcystis species. The toxins cause extensive hemorrhage in the liver, but the mode of action is still unknown.
We found that IL-6 activity was detected in the serum of mice after an intraperitonal injection of 7-desmethyl microcystin-LR(7-DMLR) that had been purified from M.aeruginosa, and that the weak activity was also detected in the supernatant of peritoneal macrophage cultures in the presence of 7-DMLR.The IL-6 induction by 7-DMLR was lowered when recombinant IL-10 had been injected 30 min before the injection of 7-DMLR.The IL-10 administration relieved the mice from lethal shock caused by microcystin. It is known that IL-6 is a inflammatory cytokine and releases acute phase inflammatory proteins from the liver. Therefore, these findings suggest that hepatotoxicity caused by microcystin is regulated by the inflammatory cytokines including IL-6 and IL-10.
Monoclonal antibodies against microcystin-LR have been prepared. However, these antibodies showed the cross-reactivity to other microcystin-variants, and very low ability to neutralize the lethal toxicty of microcystin to mice. The antibodies can react with cell-lysates prepared from non-toxic M.aeruginosas strains without microcystin as well as those from toxic strains. Therefore, the non-toxic strains may contain some antigenic molecule(s) such as precursors of microcystin, and the molecules may react with the antibodies.
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