昆虫功能性脂质与油脂的开发

昆虫脂质无论在量上还是在质上都有其可资研究和利用的特点,昆虫功能性脂质和油脂的开发具有广阔的前景。     

Evidence contrary to the existence of storage lipid in leaves of plants inhabiting cold climates

Abstract In a study of the lipid composition of the upland Empetrum nigrum subspp. hermaphroditum and Empetrum nigrum subspp. nigrum with a lowland distribution, no evidence was found to support the suggestion that lipids (triacylglycerols) play a major energy storage role in the leaves of alpine species. On a quantitative basis the triacylglycerols constituted less than 5% of the total lipid in both species and the lowland species possessed the higher levels of total lipid, neutral lipid and triacylglycerols. It is suggested that the presence of a well-developed waxy cuticle might account for the high total lipid levels encountered in dwarf evergreen shrubs.     

Fatty acids of sponges from the Sea of Okhotsk

The fatty acid (FA) composition of Demospongiae species from the Sea of Okhotsk was studied. Fifteen sponge species were investigated for the first time, and the previously studied species Desmacella rosea and Myxilla incrustans were reexamined for their FA composition. Gas chromatography-mass spectrometry revealed 150 different fatty acids, of which 15 have not been identified in sponge lipids previously. The relative content of saturated FAs varied from 7.6 in Melonachora kobjakovae to 29.6% in Amphilectus digitata, with an average of 14.6% of total FAs. The relative content of monoenic FAs ranged from 12.8 in T. dirhaphis to 27.0% in Polymastia sp., with an average of 20.6% of total FAs. Non-methylen-interrupted, primarily unsaturated Δ5,9-FAs contributed a significantly to the amount of polyunsaturated fatty acids of sponges; this being a distinguishing feature of the FA composition of the investigated group of organisms.     

Molecular breeding strategies for the modification of lipid composition

Summary Lipids are key components of all living cells. Acyl lipids and sterols provide the matrix of the biological membranes that both define the boundaries of cells and organelles, and act as sites for the trafficking of molecules within and into/out of cells. Lipids are also important metabolic intermediates and the most efficient form of energy storage that is available to a cell. It is the latter, energy-storing function that is of most relevance to this review. Storage lipids are accumulated in abundance in many of our most important crops, including maize, soybean, rapeseed, and oil palm, giving rise to a commerical sector valued at over $50 billion/year. Because the storage lipids of the major global oil crops have a relatively restricted composition, there is great interest in using all available breeding technologies, whether traditional or modern, to enhance the variation in lipid quality in existing crops and/or to domesticate new crops that already accumulate useful novel lipids. Over the past few decades, there has been a great deal of effort to manipulate fatty acid composition in order to produce novel lipids, especially for industrial applications. However, these attempts, many based on genetic engineering, have met with only limited commercial success-to date. More recently, there has been a resurgence of interest in the modification of both acyl and non-acyl lipids to enhance the nutritional quality of plant oils. In this review, we will examine the background to plant lipid modification and some of the latest developments, with a particular focus on edible oils.     

Identification of (all-cis)-6,9,12,15-octadecatetraenoic acid in Ribes nigrum and fish oils: chemical and physical characterization.

In this report, we show that the non-conjugated octadecatetraenoic acid found in the oil of the seeds from Ribes nigrum is identical to the C₁₈-polyunsaturated fatty acid previously isolated in a number of fish oils and seed oils. Evidence obtained from mass spectral data of its triazolopyridine derivative clearly indicates the presence of methylene-interrupted double bonds. Comparison with authentic material prepared by chemical synthesis provides further confirmation of the (all-cis)-6,9,12,15-octadecatetraenoic acid structure. The (all-cis)-4,8,12,15-structural arrangement erroneously attributed to this acid in several literature reports is thus definitely ruled out.     

Distribution of unusual fatty acids in the triacylglycerols of sea buckthorn mesocarp oil

The structure of unusual fatty acid (FA) components of triacylglycerols (TAGs) of mature sea buckthorn (Hippophae rhamnoides L.) mesocarp oil was determined by GLC and MS, and the positional-species composition (PSC) of these TAGs was estimated using the methods of TAG chemical deacylation, TLC, GLC, and computer calculation. It was shown that the unusual FAs comprised n-cis-Δ9-hexadecenoic, n-cis-Δ9,12-hexadecadienoic (palmitolinoleic), and n-cis-Δ11-octadecenoic (cis-vaccenic) acids. The hexadecenoic acid predominated in the oil, and in its distribution in TAGs, it was similar to the total FAs differing from them only in some prevalence in the triunsaturated TAGs and in the TAGs with a shorter acyl chain, as well as in the sn-2 position of TAGs. Palmitolinoleic (16:2) acid comprised only 5% of total FAs, and it was exclusively concentrated in the sn-2 position of TAGs. As regards its distribution between various positional types and forms of TAGs, the 16:2 acid was similar to oleate and total FAs. As compared to the total TAGs, the TAGs with 16:2 acid were characterized by a lower FA chain length as well as by a highest unsaturation. The TAGs with vaccenic acid (V-TAGs) considerably exceeded O-TAGs, i.e., the TAGs containing oleic acid, another 18:1 positional isomer, both in their content in the total TAGs and in their unsaturation. In the composition of positional types and fractions of various unsaturation, O-TAGs were similar to the total TAGs, while V-TAGs were characterized by a very unusual structure, viz., a very high triunsaturated TAG level and an extremely low concentration of 1,3-disaturated-2-monounsaturated TAGs. In addition, oleic acid, like most other unsaturated FAs, was incorporated predominantly in the sn-2 position of TAGs, while vaccenic acid, being also unsaturated, was nevertheless by 90% concentrated in the sn-1,3 positions of V-TAGs. Unusual FAs were related to each other in the mechanism of their biosynthesis. In fact, hexadecenoic acid biosynthesis produced by palmitic acid desaturation, was, on the one hand, further desaturated forming palmitolinoleic acid, and, on the other hand, converted to vaccenic acid via C₂ elongation.     

Protein acylation in the cardiac muscle like cell line,H9c2

Besides serving as oxidisable substrates, fatty acids (FA) are involved in co- and post-translational modification of proteins (protein acylation). Despite the high rate of fatty acid utilisation in the heart, information on protein acylation in cardiac muscle is scarce. To explore this subject in more detail, we used the H9c2 cell line as an experimental model. After incubation with ³H-palmitate or ³H-myristate, cells were lysed and proteins precipitated, followed by extensive delipidation. The delipidated proteins were subjected to SDS-PAGE and transferred to nitro-cellulose prior to autoradiography. In addition, TLC was used to separate the various lipid classes. The first aspect we addressed was the extent of protein acylation as a function of time, relative to fatty acid incorporation into various lipid classes. Cells were incubated for 30 min, 1 h and 2 h with 100 Ci palmitate (PA, 2.3 nmol) or 125 Ci myristate (MA, 2.5 nmol). Palmitoylation increased from 0.48 ± 0.25 to 1.25 ± 0.56 Ci/mg protein between 30 min to 2 h, while myristoylation increased from 0.25 ± 0.12 to 0.77 ± 0.36 Ci/mg protein. Furthermore, delipidated proteins subjected to autoradiography showed that a set of distinct proteins was labelled with ³H-palmitate. Incorporation into phospholipids (PL) increased from 40–60% of the total amount of radio-labelled PA or MA supplied between 30 min and 2 h. Only the FA pool differed between MA and PA, with a higher FA content present after incubations with MA. Second, we investigated palmitoylation and incorporation into cellular lipids as a function of the amount of PA applied. Palmitoylation showed saturation at high PA concentrations. The percentage incorporation of ³H-PA in the various lipids depended on the amount of PA added: a decline in the PL pool with a concomitant increase in the size of the diacylglycerol pool at high PA concentrations. Third, inhibition of palmitoylation by cerulenin and tunicamycin was investigated. While both were able to inhibit palmitoylation, cerulenin also inhibited the incorporation of PA into various lipid classes, indicating differences in inhibitory action.     

Lipid composition and storage in the tissues of the bivalve, Macoma balthica

Total lipid content, lipid classes and fatty acid composition in organs of Macoma balthica (L.) from the Gulf of Gdánsk (Puck Bay) were studied in different seasons. Marked differences among tissues in lipid class composition were observed. Triacylglycerides were accumulated in the hepatopancreas and in the female gonad in large quantities, while hydrocarbons were concentrated in male gonads, gills muscles and mantle. Fatty acid composition of gill lipids reflects the brackish water conditions of the Gulf of Gdask in which Macoma balthica occurs.     

Lipid Composition of in vitro Developing Seeds of Brassica campestris L.

A liquid culture technique has been developed to study lipid metabolism in seeds of Brassica campestris L. grown in vitro from terminal inflorescences detached 4 to 46 days after anthesis. Seeds developed under these conditions exhibited pattern of growth, deposition of storage products and lipid composition similar to those from intact plant.     

Fatty Acid Composition of Mitochondrial Membrane Lipids in Cultivated (Zea mays) and Wild (Elymus sibiricus) Grasses

The fatty acid composition of mitochondrial membrane lipids from seedlings of two grass species differing in their chilling tolerance, elymus (Elymus sibiricus) and maize (Zea mays), was studied by gas-liquid chromatography. An increased chilling tolerance of elymus, a perennial wild species, seems to be caused by a high content of unsaturated fatty acid residues in the total membrane lipids; linoleic (41.9%) and -linolenic (23.4%) acids predominated among these fatty acids. The contents of linoleic and -linolenic acids in the total lipids of maize membranes were 57.5% and 5.8%, respectively. Polar lipids of elymus mitochondrial membranes were characterized by about similar contents of linoleic (33.6%) and -linolenic (31.3%) acids. Linoleic acid (51.7%) predominated in maize mitochondrial polar lipids, whereas the -linolenic acid content was 9.0%. A high level of 3-desaturase activity in the mitochondrial membranes seems to be an important factor of elymus chilling tolerance. This high activity seems to be developed as an adaptation in the course of evolution of this species.     

Triacylglycerol and polar lipid metabolism in germinating sea buckthorn seeds

Dark germination of sea buckthorn (Hippophal rhamnoides L.) seeds was characterized by an initial 3-day-long lag-period, when the contents of triacylglycerols (TAGs) and polar lipids (PLs) remained nearly the same due to a retardation in lipid metabolization. Subsequently, TAG content declined rapidly, and by the 10th day of germination, it did not exceed 5% of total lipids. In this case, total saturated (S) and total unsaturated (U) fatty acids (FAs), as well as various TAG types such as S₂U, SU₂, and U₃, were consumed at nearly similar relative rates. At the same time, separate TAG groups, which included one of the individual FAs, such as palmitic (P), stearic (St), oleic (O), linoleic (L), or linolenic (Le), differed from each other in the intensity of degradation. For L- and Le-TAGs, initial and final concentrations were similar, while initial concentrations of St- and O-TAGs by the 10th day of germination increased 2.3- and 1.5-fold, respectively, and as regards P-TAGs, this value decreased 3.5-fold. Thus, P-TAGs considerably exceeded other TAG groups in their consumption rate in seedlings, while St- and O-TAGs ranked below them in this respect. By the 10th day, the absolute level of PLs increased 16-fold due to a de novo formation of lipid membranes of the cells in the course of growth and differentiation of seedling tissues; this increase was accompanied by an increase in the S-FA concentration in PLs and a decrease in the amount of U-FAs.