1993 Fiscal Year Final Research Report Summary
Characterization of cis- and trans-desaturation reactions in chloroplasts and their physiological significance
| Project/Area Number |
04660074
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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 |
応用生物化学・栄養化学
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| Research Institution | Obihiro University of Agriculture and Veterinary Medicine |
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Principal Investigator |
OHNISHI Masao Obihiro Univ.of Agric.and Vet.Med., Dep.Ani.Hus., Associate Professor, 畜産学部, 助教授 (90109520)
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| Project Period (FY) |
1992 – 1993
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| Keywords | chloroplast / plant lipids / desaturase / trans acid / phospholipid / membrane lipid / chilling stress |
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| Research Abstract |
Chloroplast membranes contain phosphatidylglycerol(PG) that is rich in trans-DELTA^3- hexadecenoic acid (16 : 1^t), a fatty acid found nowhere else in the cell. After labeling the green alga Dunaliella salina with exogenous [^3H]myristic acid ([^3H]14 : 0), the cis-unsaturated fatty acids of monogalactosyldiacylglycerol and sulfoquinovosyldiacylglycerol as well ad PG had higher specific radioactivities in chloroplast envelopes than in thylakoids. In contrast, 16 : 1^t was very slow to become radioactive, and its specific radioactivity was several times higher in isolated thylakoids than in envelopes after brief labeling with [^3H]14 : 0. The findings suggest that the substrates for trans-desaturation are 16 : 0-containing PG molecular species which are readily labeled from [^3H]14 : 0 in the envelope but are diluted by te large pool of thylakoid PG before penetrating to the desaturation site. By examining the labeling patterns of individual PG molecular species classes, it was concluded that 16 : 1^t is formed from 16 : 0 linked to 18 : 2/16 : 0 PG and 18 : 3/16 : 0 PG by a trans-desaturase lacated within the thylakoid compartment. From further studies on the trans-desaturase activity, it was assumed that the desaturation action takes place in some inner recess, such as the appressed region. The physiological significance of the lipid unsaturation in plant cells was also examined in relation to the mechanism for the adaptation to low temperature stress.
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Research Products
(4 results)
