海産動物プランクトンの脂質, とくに甲殼類におけるワックス・エステルの分布とIn Vivo生合成について

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Following the previous studies on the lipids of micronektonic fishes and shrimps, the present paper deals with those of marine zooplanktons, which are fed by the micronekton and play an important role in the food chain. Most of the specimens were collected in the Japan Sea, Sagami and Suruga Bays. They consisted of two species belonging to the order Amphipoda (A), three species beloging to the order Euphausiacea (B) and five species belonging to the order Calanoida (C). Besides them the zooplankters were also caught from various depths off the Kii Channel and examined. The lipid contents of crustaceans based on the wet weight were 1.4% to 3.2% in A, 1.1% to 7.7% in B, and 4.8% to 15.7% in C. The wax esters in their lipids ranged from 63.8% of Calanus sinicus to 87.9% of Pareuchaeta elongata in C, from 37.2% of Parathemisto japonica to 49.0% of Printno macropa in A, and less than 10% in B. Generally the spring specimens contained larger amounts of the lipids than the autumn ones. However, the wax contents in the lipids indicated the opposite relation. Although the wax esters cover the carbon chain-length C30 to C46, the major esters range C34 to C44 with even numbered carbons, and also a trace amounts of odd numbered esters exist. The wax esters of Parathemisto japonica and Calanus cristatus composed of rather longer esters and their composition was similar to that of micronektonic shrimps, while the wax esters of Thysanoessa longipes, Pareuchaeta elongata and Euphausia pacifica were rich in shorter ones as observed in micronektonic fishes. These differences resulted from the composition of fatty acid and fatty alcohol moieties. The former type consists dominantly of monoenoic fatty acids and alcohols such as C20 : 1 and C22 : 1, whereas the latter one contains highly unsaturated fatty acids such as C20 : 5 and C22 : 6 and rather shorter alcohols such as C16 : 0 and CC18 : 1 as major components By analyzing the lipids of mixed zooplankters obtained from the different depths, 5m, 100m, 300m, 500m and 1, 000 m, it was recognized that the deeper zooplankton contained larger amounts of wax esters and less triglycerides, and vice versa for these lipid classes of the shallower one. An attempt to test the incorporation of 14C labelled substrates into the lipid classes by the intact zooplankters caught from 1, 000 m depth was carried out. In the case of [1-14C] -cetyl alcohol 42.2% were measured in the class of wax esters, in [1-14C] -palmitic acid 18.7% and in [1-14C] -acetate 14.3% as percentage radioactivity. Considerable amounts of radioactivity were also detected in the classes of aldehydes and alcohols, suggesting the bioreduction of the donated fatty acid to them before ester formation. Finally, the analyses of amino acid composition of crustacean plankton proteins revealed that they were quite alike each other, rich in ten essential amino acids, and excellent as natural diet for fishes from the viewpoints of nutrition of proteins as well as lipids which contain abundant essential fatty acids of linolenic family (w3).
社団法人日本油化学会の論文

海産動物プランクトンの脂質, とくに甲殼類におけるワックス・エステルの分布と<I>In Vivo</I>生合成について

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