Lipid Class Composition Research Articles

Effects of growth phase and nitrogen limitation on biochemical composition of two strains of Tisochrysis lutea

Standard and mutant Tisochrysis lutea strains were grown in batch culture for 10days under nitrogen (N)-replete and N-reduced conditions to determine the effects of N supply in culture medium and growth phase on microalgal physiology and biochemistry. These two T. lutea strains were compared in terms of growth, morphology, associated free-living bacterial community, viability, intracellular lipid content (as measured by Bodipy staining), chlorophyll autofluorescence, and biochemical composition, with a focus on lipid class and fatty acid compositions. The standard strain (T) reached higher cell counts regardless of N supply in culture medium. In both T. lutea strains, microalgal final cell density was significantly lower in N-reduced medium. Carbohydrates were enhanced at stationary phase in both strains, regardless of N supply. The oleaginous strain (T+) accumulated triacylglycerols; whereas, the standard strain T accumulated alkenones as reserve lipids, especially in N-reduced medium and stationary phase. Each T. lutea strain exhibited an intrinsic specific FA profile in neutral lipids (NL) and, to a lesser extent, in polar lipids (PL) independent of N supply and growth phase. T+ contained more saturated and monounsaturated fatty acids (especially 14:0 and 18:1n-9), but less polyunsaturated fatty acids (18:4n-3 and 22:6n-3) than T. Overall, growth phase induced more changes in fatty acid profiles of both T. lutea strains in NL and PL than N supply in culture medium.

Effects of β-hydroxy-β-methylbutyrate on skeletal muscle mitochondrial content and dynamics, and lipids after 10 days of bed rest in older adults.

Loss of muscle mass during periods of disuse likely has negative health consequences for older adults. We have previously shown that β-hydroxy-β-methylbutyrate (HMB) supplementation during 10 days of strict bed rest (BR) attenuates the loss of lean mass in older adults. To elucidate potential molecular mechanisms of HMB effects on muscle during BR and resistance training rehabilitation (RT), we examined mediators of skeletal muscle mitochondrial dynamics, autophagy and atrophy, and intramyocellular lipids. Nineteen older adults (60-76 yr) completed 10 days BR followed by 8-wk RT rehabilitation. Subjects were randomized to either HMB (3 g/day HMB; n = 11) or control (CON; n = 8) groups. Skeletal muscle cross-sectional area (CSA) was determined by histology from percutaneous vastus lateralis biopsies. We measured protein markers of mitochondrial content [oxidative phosphorylation (OXPHOS)], fusion and fission (MFN2, OPA1, FIS1, and DRP1), autophagy (Beclin1, LC3B, and BNIP3), and atrophy [poly-ubiquinated proteins (poly-ub)] by Western blot. Fatty acid composition of several lipid classes in skeletal muscle was measured by infusion-MS analysis. Poly-ub proteins and OXPHOS complex I increased in both groups following BR (P < 0.05, main effect for time), and muscle triglyceride content tended to increase following BR in the HMB group (P = 0.055). RT rehabilitation increased OXPHOS complex II protein (P < 0.05), and total OXPHOS content tended (P = 0.0504) to be higher in HMB group. In addition, higher levels of DRP1 and MFN2 were maintained in the HMB group after RT (P < 0.05). BNIP3 and poly-ub proteins were significantly reduced following rehabilitation in both groups (P < 0.05). Collectively, these data suggest that HMB influences mitochondrial dynamics and lipid metabolism during disuse atrophy and rehabilitation.NEW & NOTEWORTHY Mitochondrial content and dynamics remained unchanged over 10 days of BR in older adults. HMB stimulated intramuscular lipid storage as triacylglycerol following 10 days of bed rest (BR) and maintained higher mitochondrial OXPHOS content and dynamics during the 8-wk resistance exercise rehabilitation program.

Exploring Valuable Lipids in Diatoms

Diatoms are one major group of algae in oceans that accounts almost half of marine primary food production and have also been identified as a promising candidate for biofuel production for their high level accumulation of lipids. They have gained increasingly attention for their potential applications in pharmaceuticals, cosmetics, nutrient supplements and biofuels. This review aims to summarize the recent advances in diatom lipid study. Chemical structures and bioactivities of different lipid classes are discussed with a focus on valuable lipids such as fatty acids, polar lipids, steroids, and oxylipins from various diatoms species. Further, current extraction and fractionation approaches are compared and recent analytical techniques and methods are also reviewed with an emphasis on lipid class composition and fatty acid profiling. Biosynthetic pathways and key catalyzing enzymes are illustrated for a better understanding of fatty acid metabolism. Past engineering attempts towards generating appropriate diatom strains for lipid production are discussed with examples using mutagenesis, environmental stimulants and genetic modification methods. Some possible future directions and applications of diatom-derived lipids are also proposed.

Fatty Acid and Lipid Class Composition of the Microalga Phaeodactylum tricornutum.

n-3 Polyunsaturated fatty acids (PUFAs) are essential for the prevention and/or risk reduction of some diseases, including cardiovascular diseases and cancer. Therefore, PUFAs-rich marine microalgae have received considerable research attention. The diatom Phaeodactylum tricornutum, a rich source of lipids and fucoxanthin, has commercial applications in the food and pharmaceutical industries. In this study, the lipid class composition and fatty acid distribution in P. tricornutum under high-density and scale-up cultivation were investigated by thin-layer chromatography and gas chromatography. The fucoxanthin content was quantified by reverse-phase high-performance liquid chromatography. Both total lipid and fucoxanthin contents were high, accounting for 321.89 and 4.47 mg/g dry weight, respectively. Neutral lipids were the major lipids, and triacylglycerol was the predominant neutral lipids (33.63% of total lipids). The glycolipids (GLs) and phospholipids (PLs) represented 20.95% and 31.39% of total lipids, respectively. Sulfoquinovosyl diacylglycerol (SQDG) was the largest GLs fraction (9.81% of total lipids). Phosphatidylglycerol (PG) was the major PLs and accounted for 13.53% of total lipids. The main fatty acids were hexadecanoic acid (C16:0), palmitoleic acid (C16:1), and eicosapentaenoic acid. In addition, docosahexaenoic acid only accumulated in the PLs fraction. These findings provide new information on the lipid types, fatty acid composition of each lipid class, and the fucoxanthin content in P. tricornutum.

Effects of treatment with sucrose in drinking water on liver histology, lipogenesis and lipogenic gene expression in rats fed high-fiber diet

We studied the influence of sucrose in drinking water on liver histology, fatty acid profile and lipogenic genes expression in rats maintained on high-fiber. The experimental groups were: control group (water) and sucrose group (sucrose solution in drinking water, 30% w/v). Liver histology of sucrose treated rats revealed steatosis and increased number of αSMA immunoreactive cells without the signs of fibrosis. Sucrose treatment increased de novo lipogenesis, lipid peroxidation and MUFA content and decreased PUFA content, C18:2n6 and C20:4n6 content in total phospholipids and phosphatidylethanolamine and C18:2n6 content in cardiolipin. RT-qPCR revealed increase in Δ-9-desaturase and SREBP1c gene expression and decrease in the Δ-5-desaturase and elongase 5 expression. Treatment with sucrose extensively changes fatty acid composition of hepatic lipid and phospholipid classes including cardiolipin, increases oxidative stress and causes pathological changes in liver in rats maintained on high-fiber diet.

Lipid metabolism-related gene expression pattern of Atlantic bluefin tuna (Thunnus thynnus L.) larvae fed on live prey

The present study is the first to evaluate lipid metabolism in first-feeding Atlantic bluefin tuna (ABT; Thunnus thynnus L.) larvae fed different live prey including enriched rotifers Brachionus plicatilis and Acartia sp. copepod nauplii from 2 days after hatch. Understanding the molecular basis of lipid metabolism and regulation in ABT will provide insights to optimize diet formulations for this high-value species new to aquaculture. To this end, we investigated the effect of dietary lipid on whole larvae lipid class and fatty acid compositions and the expression of key genes involved in lipid metabolism in first feeding ABT larvae fed different live prey. Additionally, the expression of lipid metabolism genes in tissues of adult broodstock ABT was evaluated. Growth and survival data indicated that copepods were the best live prey for first feeding ABT and that differences in growth performance and lipid metabolism observed between larvae from different year classes could be a consequence of broodstock nutrition. In addition, expression patterns of lipid metabolic genes observed in ABT larvae in the trials could reflect differences in lipid class and fatty acid compositions of the live prey. The lipid nutritional requirements, including essential fatty acid requirements of larval ABT during the early feeding stages, are unknown, and the present study represents a first step in addressing these highly relevant issues. However, further studies are required to determine nutritional requirements and understand lipid metabolism during development of ABT larvae and to apply the knowledge to the commercial culture of this iconic species.

Cellular effects of fluorodeoxyglucose: Global changes in the lipidome and alteration in intracellular transport.

2-fluoro-2-deoxy-D-glucose (FDG), labeled with 18F radioisotope, is the most common imaging agent used for positron emission tomography (PET) in oncology. However, little is known about the cellular effects of FDG. Another glucose analogue, 2-deoxy-D-glucose (2DG), has been shown to affect many cellular functions, including intracellular transport and lipid metabolism, and has been found to improve the efficacy of cancer chemotherapeutic agents in vivo. Thus, in the present study, we have investigated cellular effects of FDG with the focus on changes in cellular lipids and intracellular transport. By quantifying more than 200 lipids from 17 different lipid classes in HEp-2 cells and by analyzing glycosphingolipids from MCF-7, HT-29 and HBMEC cells, we have discovered that FDG treatment inhibits glucosylceramide synthesis and thus reduces cellular levels of glycosphingolipids. In addition, in HEp-2 cells the levels and/or species composition of other lipid classes, namely diacylglycerols, phosphatidic acids and phosphatidylinositols, were found to change upon treatment with FDG. Furthermore, we show here that FDG inhibits retrograde Shiga toxin transport and is much more efficient in protecting cells against the toxin than 2DG. In summary, our data reveal novel effects of FDG on cellular transport and glycosphingolipid metabolism, which suggest a potential clinical application of FDG as an adjuvant for cancer chemotherapy.

Feedstock production for third generation biofuels through cultivation of Arthrobacter AK19 under stress conditions

As a member of the third generation of biofuels, biodiesel from bacteria requires substantial further research and development to assess its viability for commercial production. However, this biofuel is a promising solution to global renewable energy demands. As a result, the cultivation of Arthrobacter AK19 was investigated for higher lipid production through media optimization parameters and stress conditions. The results showed that when the Box-Behnken design was applied, the maximum biomass concentration was 4.78 times higher than that from unoptimized condition. Additionally, with sodium chloride and potassium permanganate at a concentration of 1.5 g/l and 3.2 mg/l as a stress agent, the lipid content was 3.34 and 1.95 times higher than that obtained under normal condition. The lipid class composition of Arthrobacter AK19 under sodium chloride stress contained neutral lipids, glycolipids and phospholipids at levels of 63.45, 28.59 and 7.96 wt%, respectively. Additionally, the major components in the total lipids were linoleic acid, lignoceric acid, palmitic acid and stearic acid.

Profiling of complex lipids in marine microalgae by UHPLC/tandem mass spectrometry

Microalgal lipids are of great interest for their potential as food and feed ingredients, nutraceutical and cosmetic components, and as source of energy. Glycerol-based lipids can constitute up to 50% or more of the biomass of microalgae. How synthesis of these products takes place is still poorly explored, although remarkable differences with plants and among microalgal species have already emerged. These differences attain to both lipid class and fatty acyl composition, which could be modulated by specific growth conditions. Here we present a new method based on UHPLC coupled to high resolution tandem mass spectrometry for targeted analysis of the main lipid classes, i.e., glycolipids, phospholipids and triacylglycerols, applied to five marine microalgae exhibiting a great diversity in lipid composition. The LC/MS/MS approach is integrated with a recently proposed MTBE-based protocol for lipid extraction and the entire workflow is of general application to lipid profiling of cell extracts from different sources.

Annual cycle of lipid content and lipid class composition in zooplankton from the Beaufort Sea shelf, Canadian Arctic

We determined seasonal cycles of lipid content, lipid class composition, and carbon and nitrogen content of seven taxa of zooplankton that were collected from the Beaufort Sea shelf, Canadian Arctic, over a 10-month period (September 2003 – August 2004). All taxa except the chaetognath Parasagitta elegans had substantial lipids stores (&gt;50%), either seasonally (Oikopleura spp.) or throughout the year (Calanus hyperboreus, Calanus glacialis, Paraeuchaeta glacialis, Metridia longa, and Eukrohnia hamata). Wax esters were the dominant lipid class in the chaetognath Eukrohnia hamata and in all copepods, including the carnivore Paraeuchaeta glacialis. Seasonal trends in lipid content and composition varied among taxa; some taxa had little variation from winter through summer (e.g., Parasagitta elegans), other taxa showed little variation until summer (e.g., Calanus glacialis), and others showed increasing or decreasing trends during winter and spring (e.g., Calanus hyperboreus). Specifically, total lipid content of Calanus hyperboreus decreased from January through May at a rate of ∼450 μg·month−1·individual−1in adult females and ∼100 μg·month−1·individual−1in juvenile copepodite IV, representing a 75%–85% loss in lipid.

Lipid profiling of lipoprotein X: Implications for dyslipidemia in cholestasis

Lipoprotein X (Lp-X) is an abnormal lipoprotein that may typically be formed in intra- and extrahepatic cholestasis and potentially interfere with lipid analysis in the routine lab.To gain insight into lipid class and species composition, Lp-X, LDL and HDL from cholestatic and control serum samples were subjected to mass spectrometric analysis including phospholipids (PL), sphingolipids, free cholesterol (FC), cholesteryl esters (CE) and bile acids.Our analysis of Lp-X revealed a content of 46% FC, 49% PL with 34% phosphatidylcholine (PC) as main PL component. The lipid species pattern of Lp-X showed remarkable high fractions of mono-unsaturated species including PC 32:1 and PC 34:1 and phosphatidylethanolamine (PE) 32:1 and 34:1. LDL and HDL lipid composition in the same specimens strongly reflected the lipid composition of Lp-X with increased PC 32:1, PC 34:1, PE 32:1, PE 34:1 and FC accompanied by decreased CE compared to controls.Comparison of Lp-X and biliary lipid composition clearly indicates that Lp-X does not originate from a sole release of bile lipids. Moreover, these data present evidence for increased hepatic fatty acid and PL synthesis which may represent a reaction to high hepatic FC level observed during cholestasis.

Salinity induces membrane structure and lipid changes in maize mesophyll and bundle sheath chloroplasts.

The membranes of Zea mays (maize) mesophyll cell (MC) chloroplasts are more vulnerable to salinity stress than are those of bundle sheath cell (BSC) chloroplasts. To clarify the mechanism underlying this difference in salt sensitivity, we monitored changes in the glycerolipid and fatty acid compositions of both types of chloroplast upon exposure to salinity stress. The monogalactosyldiacylglycerol (MGDG) and digalactosyldiacylglycerol (DGDG) contents were higher in MC chloroplasts than in BSC chloroplasts, in both the presence and absence of salt treatment. Under salt conditions, the MGDG level in MC chloroplasts was significantly lower than under normal conditions, while it was unchanged in BSC chloroplasts. In both types of chloroplast, the contents of DGDG, phosphatidylglycerol and phosphatidylinositol remained at the same levels in control and salt-treated plants, whereas sulfoquinovosyldiacylglycerol and phosphatidylcholine were significantly lower and higher, respectively, upon salt treatment. In addition, the fatty acid composition and double bond index of individual lipid classes were changed by salt treatment in both BSC and MC chloroplasts, although these factors had no effect on glycerolipid content. These findings suggest that the difference in salt sensitivity of MC and BSC chloroplast membranes is related to differences in MGDG responses to salinity. Thus, we propose that the low MGDG content and the low sensitivity of MGDG to salinity in BSC chloroplasts render them more tolerant than MC chloroplasts to salinity stress.

Positional Distribution of Fatty Acids in Triacylglycerols and Phospholipids from Fillets of Atlantic Salmon (Salmo Salar) Fed Vegetable and Fish Oil Blends.

The nutritional and functional characteristics of dietary fat are related to the fatty acid (FA) composition and its positional distribution in the triacylglycerol (TAG) fraction. Atlantic salmon is an important source of healthy long chain omega 3 FA (particularly, eicosapentaenoic (EPA) and docoxahexaenoic (DHA) acids). However, the impact of lipid sources in salmon feeds on the regiospecificity of FA in the fish TAG remains to be explored. The present study determines the effect of feeding salmon with blends of palm, rapeseed, and fish oil, providing two different EPA + DHA concentrations (high: H-ED 10.3% and low: L-ED 4.6%) on the fillet lipid class composition and the positional distribution of FA in TAG and phospholipids. The regiospecific analysis of fillet TAG showed that around 50% of the EPA and around 80% of DHA was located in the sn-2 position. The positional distribution of FA in phosphatidylcholine (PC), showed that around 80% of the EPA and around 90% of DHA were located in the sn-2. Fish fed the vegetable-rich diets showed higher EPA in the sn-2 position in PC (77% vs. 83% in the H-ED and L-ED diets, respectively) but similar DHA concentrations. It is concluded that feeding salmon with different EPA + DHA concentrations does not affect their positional distribution in the fillet TAG.

Lipid composition of the three co-existing Calanus species in the Arctic: impact of season, location and environment

Arctic species of Calanus are critical to energy transfer between higher and lower trophic levels and their relative abundance, and lipid content is influenced by the alternation of cold and warm years. All three species of Calanus were collected during different periods in Kongsfjorden (Svalbard, 79°N) and adjacent shelf during the abnormally warm year of 2006. Lipid composition and fatty acid structure of individual lipid classes were examined in relation with population structure. Wax esters dominated the neutral lipid fraction. Phosphatidylcholine (PC) dominated the structural lipids followed by phosphatidylethanolamine (PE). PC/PE ratios of 3–6 suggested an increase in PC proportions compared to earlier studies. Depending on the time scale, fatty acids of wax esters illustrated either trophic differences between fjord and offshore conditions for C. hyperboreus and C. finmarchicus or trophic differences related to seasonality for C. glacialis. Similarly, seasonality and trophic conditions controlled the changes in fatty acids of triglycerides, but de novo synthesis of long-chain monoenes suggested energy optimization to cope with immediate metabolic needs. Polar lipids fatty acid composition was species specific and on the long-term (comparison with data from the past decade) composition appears related to changes in trophic environment. Fatty acid composition of PC and PE indicated relative dominance of 20:5n-3 in PC and 22:6n-3 in PE for all three species. The combination of PE and PC acyl chain and phospholipid head group restructuring indicates an inter-annual variability and suggests that membrane lipids are the most likely candidate to evaluate adaptive changes in Arctic copepods to hydrothermal regime.

Fatty acid, lipid class, and phospholipid molecular species composition of the soft coral Xenia sp. (Nha Trang Bay, the South China Sea, Vietnam).

The soft corals of the genus Xenia are common for Indo-Pacific reef ecosystems. Lipid class, fatty acid (FA), phospho- and phosphonolipid molecular species compositions were identified for the first time in the soft coral Xenia sp. from Vietnam. Total lipids consisted predominantly of waxes, monoalkyl diacylglycerols, triacylglycerols, sterols, and polar lipids (21.4, 7.7, 14.2, 10.5, and 36.7 %, respectively). Sesquiterpene alcohol, valerenenol, was found. Acids 16:0, 18:3n-6, 20:4n-6, and 20:5n-3 dominated in total FA. The markers of zooxanthellae (18:4n-3 and 18:5n-3) and octocorals (24:5n-6 and 24:6n-3) were detected. Acids 18:5n-3, 20:4n-6, 22:4n-6, and 24:5n-6 concentrated in FA of polar lipids, whereas 14:0, 16:0, 16:1n-7, 18:2n-6, and 18:3n-6 were the major FA of neutral lipids. ChoGpl, EtnGpl, SerGpl, CAEP, PtdIns, and lyso ChoGpl constituted 39.5, 20.8, 20.5, 9.7, 4.3, and 5.3 %, respectively, of the sum of phospho- and phosphonolipids. Thirty-two molecular species of phospholipids and ceramide aminoethylphosphonate (CAEP) were determined by high resolution tandem mass spectrometry. Lyso 18:0e PakCho (4.1 %), 18:0e/20:4 PakCho (20.5 %), 18:1e/20:4 PlsEtn (18.0 %), 18:0e/24:5 PakSer (14.0 %), and 16:0 CAEP (9.6 %) were the major molecular species. EtnGpl and PtdIns mainly consisted of alkenyl acyl and diacyl forms, respectively. Alkyl acyl forms predominated in ChoGpl and SerGpl. Acid 24:5n-6 was a principal FA in SerGpl, whereas 20:4n-6 was more abundant in ChoGpl and EtnGpl. PtdIns contained various C20-24 PUFA. In the context of chemotaxonomy of corals, Xenia sp. has the lipid composition typical for soft corals and the FA profile similar to that of alcyonarians with the high level of 18:3n-6.

Vegetable re-esterified oils in diets for rainbow trout: Effects on fatty acid digestibility

The present study aimed at determining the effect of re-esterified oils with different monoacylglycerol (MAG) content, produced from two different vegetable sources with different degrees of saturation, palm and rapeseed, on fatty acid digestibility in rainbow trout. Re-esterified oils were obtained from a chemical esterification process using acid oils (free fatty acids (FFA)-rich by-products from the refining of vegetable oils) and glycerol (by-product of biodiesel production). This process, which produces the formation of triacylglycerols (TAG), reduces the content of FFA present in the acid oil and generates a redistribution of the fatty acids in the glycerol molecule. This redistribution could increase the amount of saturated fatty acids (SFA) located at the sn-2 position of acylglycerols. Moreover, it allows obtaining fats with a certain proportion of MAG, known for being good emulsifiers. Therefore, a higher nutritive value of re-esterified oils than that of acid oils might be expected. A 21-day feeding trial where triplicate groups of rainbow trout were fed nine experimental diets formulated to contain a 21% of different experimental oils was carried out. For each source, four different types of oil were used: native, re-esterified low in MAG, re-esterified high in MAG and acid. A commercial fish oil was used for the control diet. Although re-esterified oils had better apparent digestibility coefficients (ADC) of SFA than their corresponding acid oil diets, no improvement in SFA digestibility was observed in rainbow trout fed re-esterified oils diets compared to those fed native oil diets, not even when a high content of MAG was present. Although this improvement did not occur, both palm and rapeseed re-esterified oils could be incorporated as a fat source in diets for rainbow trout without negatively affecting fatty acid digestibility values. The study concluded that fatty acid digestibility in the experimental oils was more affected by their degree of saturation than by their positional distribution and lipid class composition of the oils.

Dynamics of lipid and fatty acid composition of the hyperiid amphipod Themisto: a bipolar comparison with special emphasis on seasonality

Themisto in polar regions represents a direct link between the zooplankton community and higher predators. Lipid characteristics were reviewed for both polar populations: T. libellula and T. abyssorum in the Arctic, and T. gaudichaudii in the Antarctic. Lipids composition showed similarities for all species with lipid class structures dominated by neutral lipids and similar composition of fatty acid membrane lipids. Differences reflect specificities of food web structure. In the Arctic, feeding on Calanus resulted in high accumulation of wax esters, and high content in long-chain monoenes in triglycerides and wax esters. In the Antarctic, feeding on different calanoid copepods resulted in a dominance of triglycerides and high 18:1n-9 content in both neutral lipid classes. Strong similarities in total fatty acid composition of summer-collected Themisto were observed in both polar systems. In addition to summer published data, a seasonal survey of adult lipid composition was carried out in Kerguelen Bay over 18 months. Lipid class composition showed maximum values of neutral lipids in fall-winter to cope with low food abundance and late winter reproduction. The results concerning fatty acid structure underline the influence of the summer–winter and winter–spring transitions: triglycerides and wax ester fatty acid changes showed in winter maximum percentages of 18:1n-9 and minimum content of polyunsaturated fatty acids. It emphasized the overwintering strategy with continuous feeding, relative stability of lipid content but decreasing percentages of polyunsaturated acids in wax esters (mostly 18:4n-3), and to a lesser extent triglycerides (mostly 20:5n-3 and 22:6n-3) to maintain stability in phospholipids fatty acid composition.

Lipids from Seeds of Linum humile

Lipids from seeds of Linum humile cultivated in Uzbekistan were studied for the first time. It was found that seeds of this flax species contained 10% less oil than those of L. humile grown at northern latitudes of the European region. The contents and compositions of lipid groups and classes in addition to their fatty-acid compositions were established. The principal group of bound lipids was phospholipids. Lipid fatty acids were represented by 10-14 constituents with 18:1 and -18:3 dominating the free lipids; 16:0 and 18:1, the bound lipids. The composition of unsaponifiable substances was determined. Linum humile Mill. (oil flax) (Linaceae) is the only cultivated species of five in the genus Linum (L. macrorrhizum Juz.; L. mesostylum Juz. ex Nevski; L. olgae Juz.; L. corymbulbosum Rehb.), grows in Uzbekistan (1), and is cultivated in unirrigated fields of the republic. A different flax species, L. usitatissimum, has the greatest agricultural significance. It is used to produce fiber; its seeds, for reprocessing as planting stock and oil production. Seed oil of L. usitatissimum is an edible oil. However, it is also used for technical purposes to manufacture lacquers, cured oils, pastes, glues, etc. (2). The uniqueness of flax oil consists of a very high content (up to 56%) of polyunsaturated -linolenic acid (18:33), an essential fatty acid in the human diet that acts as a hormone in important biological functions in vivo in humans. Currently, flax oil is widely used to treat patients with impaired lipid exchange and to prepare drugs to treat atherosclerosis, hypertension, skin burns, and other diseases (3). The quantitative content of fatty oil in flax seeds and its qualitative composition can change depending on the cultured forms and varieties and the geographic and climatic growing conditions. The oil content in L. humile seeds grown in the European region reached 52-54% (3). We did not find information in the available literature on the lipid composition of L. humile seeds. We investigated seed lipids from L. humile collected in Fergana valley. Oil (or free lipids, FL) was isolated from seeds in a Soxhlet apparatus using benzine; bound lipids (BL), from the remaining pulp by infusion with CHCl 3 -MeOH. The principal characteristics of L. humile seeds and their FL and BL are given below:

Comprehensive and quantitative profiling of lipid species in human milk, cow milk and a phospholipid-enriched milk formula by GC and MS/MSALL.

Here we present a workflow for in-depth analysis of milk lipids that combines gas chromatography (GC) for fatty acid (FA) profiling and a shotgun lipidomics routine termed MS/MSALL for structural characterization of molecular lipid species. To evaluate the performance of the workflow we performed a comparative lipid analysis of human milk, cow milk, and Lacprodan® PL-20, a phospholipid-enriched milk protein concentrate for infant formula. The GC analysis showed that human milk and Lacprodan have a similar FA profile with higher levels of unsaturated FAs as compared to cow milk. In-depth lipidomic analysis by MS/MSALL revealed that each type of milk sample comprised distinct composition of molecular lipid species. Lipid class composition showed that the human and cow milk contain a higher proportion of triacylglycerols (TAGs) as compared to Lacprodan. Notably, the MS/MSALL analysis demonstrated that the similar FA profile of human milk and Lacprodan determined by GC analysis is attributed to the composition of individual TAG species in human milk and glycerophospholipid species in Lacprodan. Moreover, the analysis of TAG molecules in Lacprodan and cow milk showed a high proportion of short-chain FAs that could not be monitored by GC analysis. The results presented here show that complementary GC and MS/MSALL analysis is a powerful approach for characterization of molecular lipid species in milk and milk products.Practical applications: Milk lipid analysis is routinely performed using gas chromatography. This method reports the total fatty acid composition of all milk lipids, but provides no structural or quantitative information about individual lipid molecules in milk or milk products. Here we present a workflow that integrates gas chromatography for fatty acid profiling and a shotgun lipidomics routine termed MS/MSALL for structural analysis and quantification of molecular lipid species. We demonstrate the efficacy of this complementary workflow by a comparative analysis of molecular lipid species in human milk, cow milk, and a milk-based supplement used for infant formula.

Influence of one selectedTisochrysis luteastrain rich in lipids onCrassostrea gigaslarval development and biochemical composition

Effects of a remarkably high overall lipid Tisochrysis lutea strain (T+) upon gross biochemical composition, fatty acid (FA), sterol and lipid class composition of Crassostrea gigas larvae were evaluated and compared with a normal strain of Tisochrysis lutea (T) and the diatom Chaetoceros neogracile (Cg). In a first experiment, the influence of different single diets (T, T+ and Cg) and a bispecific diet (TCg) was studied, whereas, effects of monospecific diets (T and T+) and bispecific diets (TCg and T+Cg) were evaluated in a second experiment. The strain T+ was very rich in triglycerides (TAG: 93–95% of total neutral lipids), saturated FA (45%), monounsaturated FA (31–33%) and total fatty acids (4.0–4.7 pg cell−1). Larval oyster survival and growth rate were positively correlated with 18:1n-7 and 20:1n-7, in storage lipids (SL), and negatively related to 14:0, 18:1n-9, 20:1n-9, 20:4n-6 and trans-22-dehydrocholesterol in membrane lipids (ML). Surprisingly, only the essential fatty acid 20:5n-3 in SL was correlated positively with larval survival. Correlations suggest that physiological disruption by overabundance of TAG, FFA and certain fatty acids in larvae fed T+ was largely responsible for the poor performance of these larvae. ‘High-lipid’ strains of microalgae, without regard to qualitative lipid composition, do not always improve bivalve larval performance.