2006 Fiscal Year Final Research Report Summary
A study on ASP toxin production mechanism in diatom
| Project/Area Number |
17580182
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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 |
Fisheries chemistry
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| Research Institution | Kitasato University |
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Principal Investigator |
KOTAKI Yuichi Kitasato University, School of Fisheries Sciences, Associate Professor, 水産学部, 助教授 (30113278)
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| Co-Investigator(Kenkyū-buntansha) |
KODAMA Masaaki Kitasato University, School of Fisheries Sciences, Professor, 水産学部, 教授 (40050588)
TAKEDA Shigenobu Tokyo University, Graduate school of Agricultural and Life Science, Associate Professor, 大学院農学生命研究科, 助教授 (20334328)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Amnesic shellfish poisoning / domoic acid / Pseudo-nitzschia multiseries / Nitzschia navis-varingica / diatom / isodomoic acid / iron / bacteria |
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| Research Abstract |
Domoic acid (DA) production by bacteria itself was investigated in Pseudo-nitzschia multiseries culture. Non-axenic cell-free medium prepared from 1-or 3-week culture was further cultured for 5 weeks under the same conditions. No DA production was observed during the entire culture period, suggesting that bacteria itself does not produce DA even in P multiseries culture that shows high level of DA. DA production of axenic culture was investigated when cultured in non-axenic P multiseries culture separating with dialysis membrane (m. w 50,000 cut off). Before 3-week, axenic culture cells showed no or trace amount of DA. After 3-week, DA content of axenic cells increased significantly. DA contents were comparable to that of non-axenic cells, suggesting that DA production of axenic cells occurred in association with some compounds smaller than m. w. 50,000 came from non-axenic culture. Nitzschia navis-varingica culture was examined for DA production and iron uptake. DA content of the diatom cells increased as the iron content of the cells increased during the stationary growth phase, suggesting that DA might be produced in association with the uptake of insoluble iron as in case of P. multiseries. X navis-varingica isolated from the Philippines was confirmed to produce not only DA but also isodomoic acids A (IA) and B (TB). Isolates from only 3 limited areas produced IA and IB instead of DA. Many other isolates from other places produced DA and IB. ASP toxin composition of N. navis-varingica was investigated outside the Philippines, resulting in confirmation that many N. navis-varingica produces DA and TB and only limited isolates described above produces IA and TB. Toxin composition in non-axenic sub-strain was stable, but one axenic sub-strain changed its original toxin composition DA-IB to IA-TB, suggesting that some bacteria or combination of bacteria might effect the toxin composition of N navis-varingica.
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Research Products
(17 results)
