| Project/Area Number |
09670286
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bacteriology (including Mycology)
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| Research Institution | Kagawa Medical University |
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Principal Investigator |
MATSUSHITA Osamu (1999) Kagawa Medical University, Microbiology, assistant professor, 医学部, 助教授 (00209537)
南 純三朗 (1997-1998) 香川医科大学, 医学部, 助教授 (40157566)
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| Co-Investigator(Kenkyū-buntansha) |
KATAYAMA Seiichi Kagawa Medical University, Microbiology, research associate, 医学部, 助手 (70169473)
OKABE Akinobu Kagawa Medical University, Microbiology, professor, 医学部, 教授 (20093677)
松下 治 香川医科大学, 医学部, 助手 (00209537)
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| Project Period (FY) |
1997 – 1999
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| Project Status |
Completed (Fiscal Year 1999)
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| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 1999: ¥100,000 (Direct Cost: ¥100,000)
Fiscal Year 1998: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1997: ¥2,700,000 (Direct Cost: ¥2,700,000)
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| Keywords | Clostridium perfringens / epsilon-toxin / lambda-toxin / mouse lethality / hippocampus / trypsin / トリプシン / ε毒素 / 組換え毒素 |
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| Research Abstract |
1. The activation of Clostridium perfringens epsilon-prototoxin (ε-prototoxin) by λ-toxin, trypsin and chymotrypsin was examined. The mouse lethality test showed that the 50% lethal doses (LDィイD250ィエD2) of the prototoxin with and without λ-toxin treatment were 110 and 70,000 ng/kg of body weight, respectively. LDィイD250ィエD2 of the prototoxin treated with trypsin and trypsin plus chymotrypsin were 320 and 65 ng/kg of body weight, respectively. Determination of the N-terminal amino acid sequence of each activated 8-prototoxin revealed that λ-toxin cleaved between the 10th and 11th amino acid residues from the N-terminus of the prototoxin, while trypsin and trypsin plus chymotrypsin did so between the 13th and 14th amino acid residues. The C-terminus deduced from the molecular weight is located at the 23th or 30th amino acid residue from the C-terminus of the prototoxin, suggesting that removal of not only N- but also C-terminal peptides is responsible for the activation of the prototoxin.
2. The neurotoxicity of ε-toxin was examined by histological examination of the rat brain. Injection of ε-toxin at a sublethal dose, 50 ng/kg, caused neuronal damage predominantly in the hippocampus: pyramidal cells in the hippocampus showed marked shrinkage and karyopyknosis, and the cells lost the immunoreactivity to microtubule-associated protein 2 (MAP-2). Timm's zinc staining revealed that zinc ions were depleted in the mossy layers of the CA3 subfield containing glutamate as a synaptic transmitter. Prior injection of either a glutamate-release inhibitor or glutamate-receptor antagonist protected the hippocampus from the neuronal damage caused by 8-toxin. These results suggest that 8-toxin acts on the glutamatergic system and evokes excessive release of glutamate, leading to neuronal damage.
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