The Establish of Four Kinds of Chinese Primary Economic Crab Species Fatty Acid Fingerprints

In order to establish our common economic crabs fatty acid fingerprints, the total lipid and phospholipid fatty acid composition of our common economic crabs were determined and analyzed by GC-MS. The results show that: the highest proportion of Eriocheir sinensis is monounsaturated fatty acid (MUFA), while the highest proportion of the other three crab is polyunsaturated fatty acid (PUFA). The percentage of EPA+DHA in Total fat of four kinds of crab is between 7.58%~36.82% .The ratio of EPA and DHA of three kinds of sea crab is higher than it in Eriocheir sinensis. Through the comparative analysis of the fatty acid composition of the total lipid and the phospholipids, we identified seven characteristic fat acids of the four species of crabs.They are C16:0, C18:1n-9, C18:2n-6, C18:3n-3, C20:5n-3, C22:6n-3,and PUFA(PL). Chemical information of four kinds of crabs in lipid composition can be mastered through fatty acids fingerprints of four kinds of crabs which used seven kinds of characteristic fatty acid as index.

Fatty Acid Analysis of Edible Oils

To research the characteristics of rice bran oil ( RBO) and identify RBO from vegetable oils,33 kinds of rice were collected from China, the fatty acids of rice bran oil, palm oil, rapeseed oil, cottonseed oil, soybean oil, peanut oil, camellia oleosa seed oil were analyzed by Gas Chromatography, the contents were determinated by area normalization method. Fingerprint of RBO is bulid, the similarity of chromatographic fingerprint (SCF) is over 0.998, means that different RBO have the same fatty acid gas chromatographic fingerprint feature. The composition and content are different in the 7 vegetable oils ,that contribute to determinate the adulteration of inexpensive oils to RBO based on SCF. Main fatty acids in peanut oil are palmitic acid, oleic acid, linoleic acid. The characteristic fatty acid is behenic acid C22:0. Main fatty acids in soybean oil are palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid. Proportion of C18:3 is much higher than in RBO when C18:1 is lower obviously. Main fatty acids in cottonseed oil are palmitic acid, oleic acid, linoleic acid. Proportion of C16:0 is much higher than in RBO and C18:1 lower . Main fatty acids in palm oil are palmitic acid, stearic acid, oleic acid, linoleic acid. Decanoic acid C10:0 is one of the characteristic fatty acids ,and C16:0 is much higher than in RBO. Main fatty acids in rapeseed oil are palmitic acid, oleic acid, linoleic acid, linolenic acid, arachidonic acid, erucic acid.C22:1 is the characteristic fatty acid when little or zero in other oils. Main fatty acids in camellia oleosa seed oil are palmitic acid, oleic acid, linoleic acid.C18:1 is much higher than RBO.

Synthesis of fatty acids by the parasite Exeristes comstockii (Hymenop.) and two hosts, Galleria mellonella (Lep.) and Lucilia sericata (Dip.)

In contrast with many other insects, whose characteristic fatty acid compositions are influenced to a limited extent by dietary fatty acid composition, the fatty acid composition of the total lipid of the ichneumonid parasite Exeristes comstockii is very similar to that of its diet, that is, the host on which it is reared. When the parasite was reared on two hosts, Lucilia sericata and Galleria mellonella, with very different fatty acid patterns, it retained no characteristic fatty acid composition of its own.Radioisotope studies demonstrated that Exeristes comstockii, Galleria mellonella and Lucilia sericata incorporate 14C from 14C-1-acetate into fatty acids with radioactivity distributions consistent with de novo, elongation, and desaturation synthetic mechanisms.Exeristes comstockii was found to incorporate 14C-1-acetate into fatty acids at higher rates than either host. It appears, therefore, that the parasite has a fatty acid metabolism of its own, with respect to synthesis and turnover, although the fatty acids are qualitatively and quantitatively very similar to those in the host. The origin of the fatty acids of E. comstockii is partially explained by synthesis of fatty acids at different rates than its host, and direct incorporation of host fat, but the parasite appears to lack to great extent the control over pool size normally present in other insects.

The consistency of the fatty acid pattern of Galleria mellonella, reared on fatty acid supplemented diets

Dietary supplements of stearic, palmitoleic, and linoleic acids, as representative of saturated, mono-unsaturated, and polyunsaturated fatty acids, respectively, did not appreciably affect the relative composition of fatty acids in waxmoth larvae. Frass analysis demonstrated that most of the fatty acids in excess of their relative composition in the insect are excreted and speculations are made as to the possible mechanism involved in the retention of the characteristic fatty acid pattern.

FATTY ACID COMPOSITION OF EXERISTES COMSTOCKII (CRESS) REARED ON DIFFERENT HOSTS

The ichneumonid parasitoid Exeristes comstockii apparently has no characteristic fatty acid composition of its own but duplicates that of its host. Thus it differs from three species of Diptera previously studied which, irrespective of diet, synthesize fatty acids and retain patterns characteristic of the species.