| Project/Area Number |
06660254
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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 |
Fisheries chemistry
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| Research Institution | HOKKAIDO UNIVERSITY |
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Principal Investigator |
ITABASHI Yutaka Hokkaido Univ., Fac.of Fish., Ass.Pro., 水産学部, 助教授 (60142709)
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| Co-Investigator(Kenkyū-buntansha) |
MIYASHITA Kazuo Hokkaido Univ., Fac.of Fish., Ass.Pro., 水産学部, 助教授 (10182015)
MATSUNAGA Katsuhiko Hokkaido Univ., Fac.of Fish., Pro., 水産学部, 教授 (90001619)
OTA Toru Hokkaido Univ., Fac.of Fish., Pro., 水産学部, 教授 (20001612)
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| Project Period (FY) |
1994 – 1995
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| Project Status |
Completed (Fiscal Year 1995)
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| Budget Amount *help |
¥2,100,000 (Direct Cost: ¥2,100,000)
Fiscal Year 1995: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1994: ¥1,600,000 (Direct Cost: ¥1,600,000)
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| Keywords | Heterosigama akashiwo / Phaeodactylum tricornutum / Free fatty acids / Licosapentaenoic acid / Monogalactosyldiacylglycerols / Phospholipase A1 / Phospholipase A2 / Iipase / ホスホリパーゼA / ヘキサデセン酸 / HPLC |
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| Research Abstract |
Determination of made of free fatty acids (FFA) and phospholipase A (PLaseA) activity in the diatom Paeodactylum tricornutum and the raphidophyte flagellate Heterosigma akashiwo, which is a causative phytoplankton of red tides.
P.tricornutum in the mid-logarithmic phase, early stationary phase and late stationary phase in a batch culture system at 20C was found to contain 16,29 and 46% FFA of total lipid, along with larger amounts of polar lipids (PL) and smaller amounts of triacylglycerols (TG), hydrocarbons and sterols. At a lower temperature (5C), the FFA content in each growth phase was reduced to 1,18 and 32%, respectively. FFA composition was characterized by much 20 : 5 (n-3).
H.akashiwo in the same culture system as P.tricornutum at 20C was found to contain only 2-4% FFA of total lipid in each growth phase, along with PL of more than 90%. TG was contained only in the late statinary phase, accounting for 3% of total lipid. Major components of FFA were 16 : 0 and 20 : 5 (n-3). These fatty acids were predominantly distributed in the sn-1 position of monogalactosyldiacylglycerol molecules, which were a major lipid class of H.akashiwo. In phosphatidylcholine molecules, on the other hand, 20 : 5 (n-3) was distributed in both sn-1 and sn-2 positions.
Acetone powders prepared from P.tricornutum and H.akashiwo showed PLaseA activity toward dioleoylphosphatidylcholines and virtually no lipase activity for TG could be detected. Free fatty acids in the both phytoplanktons would thus appear to released primarily from PL by PLaseA.The greater activity of PLaseA1 compared to PLaseA2 is discussed.
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