The effects of season on fat and fatty acids contents of shrimp and prawn species

The effects of seasons on the lipid content and fatty acid compositions of five different shrimp and prawn species (green tiger prawn – Penaeus semisulcatus, kuruma prawn – Marsupenaeus japonicus, caramote prawn – Melicertus kerathurus, deepwater pink shrimp – Parapenaeus longirostris, speckled shrimp – Metapenaeus monoceros) were evaluated. Results showed that lipid content ranged from 0.89 to 1.55% in muscle, showing that all species were considered as lean. There were significant differences (p<0.05) in the levels of saturated fatty acids (SFA), monounsaturated fatty acids and polyunsaturated fatty acids (PUFA) in terms of season and species. They were rich in n‐3 fatty acids, especially eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The highest proportions of EPA were obtained from kuruma prawn (180.9 mg/100 g) in spring and deepwater pink shrimp (173.2 mg/100 g) and caramote prawn (146.3 mg/100 g) in summer. Kuruma prawn had the highest DHA in spring (140.8 mg/100 g) followed by deepwater pink shrimp (132.2 mg/100 g) and caramote prawn (129.6 mg/100 g) in summer. The results also showed that the seasons affected lipid content and the fatty acid composition of shrimp and prawn species. Practical Application: The beneficial effect of seafood consumption on human health has been related to the high content of n‐3 fatty acids, especially EPA (20:5n‐3) and DHA (22:6n‐3). The ratios of n‐6/n‐3, PUFA/SFA and EPA + DHA are considered as useful criteria for comparing relative nutritional and oxidation values of marine oils. In the current study, the influence of seasonality on the lipid content and the fatty acid compositions of shrimp and prawn were investigated in order to find the best source of n‐3 fatty acids during the year.     

Chemical Characterization of Six Microalgae with Potential Utility for Food Application

Microalgae contain high levels of proteins, carbohydrates, and lipids, and have found a useful application in enhancing the nutritional value of foods. These organisms can also synthesize long‐chain fatty acids in the form of triacylglycerols, such as α‐linolenic acid (ALA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), linolenic acid (LA), γ‐linolenic acid (GLA) and arachidonic acid (AA). The aim of this study was to determine the chemical composition and measure protein, carbohydrates, fibers, lipids as well as the fatty acids composition of six microalgae species with potential application in the food industry. Two freshwater species, Chlorella vulgaris and Spirulina platensis, and four marine species, Nannochloropsis oculata, Nannochloropsis gaditana, Porphyridium cruentum, and Phaeodactylum tricornutum, were used in the experiments. Intracellular protein was the most prominent algal component (42.8–35.4 %), followed by carbohydrate + fiber (32.3–28.6 %), and lipids (15.6–5.3 %). N. gaditana is rich in saturated fatty acids, mainly palmitic acid (5.1 g/100 g), while the cells of S. platensis and C. vulgaris algae are abundant in GLA (1.9 g/100 g) and ALA (2.8 g/100 g) acids, respectively. P. cruentum differs from other algae, because it contains a large amount of AA (3.7 g/100 g). The marine microorganisms N. oculata and P. tricornutum are also a source of essential long‐chain polyunsaturated fatty acids (LC‐PUFA‐?3), mainly composed of EPA and DHA. Our results suggest that the freshwater species C. vulgaris and S. platensis are attractive nutritional supplements because of their low fiber and high protein/carbohydrate contents, while the marine species P. tricornutum and N. oculata can enrich foods with LC‐PUFA‐ω3, because of their favorable ω3/ω6 ratio.     

Strategies for the enzymatic enrichment of PUFA from fish oil

PUFA from oil extracted from Nile perch viscera were enriched by selective enzymatic esterification of the free fatty acids (FFA) or by hydrolysis of ethyl esters of the fatty acids from the oil (FA‐EE). Quantitative analysis was performed using RP‐HPLC coupled to an evaporative light scattering detector (RP‐HPLC‐ELSD). The lipase from Thermomyces lanuginosus discriminated against docosahexaenoic acid (DHA) most, resulting in the highest DHA/DHA‐EE enrichment while lipase from Pseudomonas cepacia discriminated against eicosapentaenoic acid (EPA) most, resulting in the highest EPA/EPA‐EE enrichment. The lipases discriminated between DHA and EPA with a higher selectivity when present as ethyl esters (EE) than when in FFA form. Thus when DHA/EPA were enriched to the same level during esterification and hydrolysis reactions, the DHA‐EE/EPA‐EE recoveries were higher than those of DHA/EPA‐FFA. In reactions catalysed by lipase from T. lanuginosus, at 26 mol% DHA/DHA‐EE, DHA recovery was 76% while that of DHA‐EE was 84%. In reactions catalysed by lipase from P. cepacia, at 11 mol% EPA/EPA‐EE, EPA recovery was 79% while that of EPA‐EE was 92%. Both esterification of FFA and hydrolysis of FA‐EE were more effective for enriching PUFA compared to hydrolysis of the natural oil and are thus attractive process alternatives for the production of products highly enriched in DHA and/or EPA. When there is only one fatty acid residue in each substrate molecule, the full fatty acid selectivity of the lipase can be expressed, which is not the case with triglycerides as substrates.     

EPA and DHA in microalgae: Health benefits,biosynthesis, and metabolic engineering advances

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are ω-3 very long-chain polyunsaturated fatty acids (VLC-PUFAs) that offer a wide range of human health benefits impacting cardiovascular, anti-inflammatory, and neurological health. It is widely known that humans inefficiently synthesize these compounds and as such rely on exogenous dietary sources, such as marine fish oils. Unfortunately, the production of marine fish oils is an unsustainable process and has suffered a dramatic fall in recent years due to overfishing and climate change, as the demand for EPA and DHA continues to rise. Therefore, there is an urgent need to develop alternative, sustainable sources for consumable EPA and DHA. Metabolic engineering of marine microalgae to improve their EPA and DHA productivity is regarded as a promising option that has received increasing commercial attention in recent years. In this mini-review, we describe several notable health benefits of EPA and DHA, summarize the natural sources and biosynthesis of VLC-PUFAS, as well as the recent advances in metabolic engineering of EPA and DHA production in representative microalgal and protist species, including Schizochytrium sp., Phaeodactylum tricornutum, and Nannochloropsis oceanica.     

Improving Fatty Acid Composition of Lipids Synthesized by Brachionus plicatilis in Large Scale Experiments

Nannochloropsis oculata and Chlorella sp. were cultivated in industrial scale bioreactors 300?L, under full sunlight and artificial light during night-time at various temperatures. The most abundant fatty acids were C18:3n-3 and C16:0 in Chlorella sp., whereas in N. oculata C16:0, eicosapentaenoic acid (EPA) and C16:1n-9 were predominant. Brachionus plicatilis cultivated in 2,500-L tanks on N. oculata, Chlorella sp. and Saccharomyces cerevisiae, was able to de novo synthesize as well as to elongate and desaturate pre-existing fatty acids in the feed. When fed with S. cerevisiae, B. plicatilis synthesized lipids containing EPA and docosahexaenoic acid (DHA), despite the fact that these fatty acids were absent in yeast lipids. Brachionus fed with Nannochloropsis synthesized DHA in non-negligible quantities. Brachionus enriched with various commercial preparations incorporated into its lipids substrate fatty acids but also synthesized new fatty acids such as C16:1n-9, C18:1n-9, C18:2n-6, EPA and DHA. Neutral lipid was the main lipid fraction while phospholipids predominated over glycolipids plus sphingolipids. The major amounts of EPA and DHA were observed in neutral lipids, noteworthy quantities of these fatty acids were also incorporated into body phospholipids. Interestingly, the high n-3 fatty acids content of rotifer lipids was retained even after the rotifers were grown in low n-3 fatty acid media.     

Determination of Substrate Preferences for Desaturases and Elongases for Production of Docosahexaenoic Acid from Oleic Acid in Engineered Canola

Production of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in plant seed oils has been pursued to improve availability of these omega‐3 fatty acids that provide important human health benefits. Canola (Brassica napus), through the introduction of 10 enzymes, can convert oleic acid (OLA) into EPA and ultimately DHA through a pathway consisting of two elongation and five desaturation steps. Herein we present an assessment of the substrate specificity of the seven desaturases and three elongases that were introduced into canola by expressing individual proteins in yeast. In vivo feeding experiments were conducted with 14 potential fatty acid intermediates in an OLA to DHA pathway to determine the fatty acid substrate profiles for each enzyme. Membrane fractions were prepared from yeast expression strains and shown to contain active enzymes. The elongases, as expected, extended acyl‐CoA substrates in the presence of malonyl‐CoA. To distinguish between enzymes that desaturate CoA‐ and phosphatidylcholine‐linked fatty acid substrates, we developed a novel in vitro method. We show that a delta‐12 desaturase from Phytophthora sojae, an omega‐3 desaturase from Phytophthora infestans and a delta‐4 desaturase from Thraustochytrium sp., all prefer phosphatidylcholine‐linked acyl substrates with comparatively low use of acyl‐CoA substrates. To further validate our method, a delta‐9 desaturase from Saccharomyces cerevisiae was confirmed to use acyl‐CoA as substrate, but could not use phosphatidylcholine‐linked substrates. The results and the assay methods presented herein will be useful in efforts to improve modeling of fatty acid metabolism and production of EPA and DHA in plants.     

Analysis of lipids extracted from salmon (Salmo salar) heads by commercial proteolytic enzymes

Fresh salmon heads were submitted to controlled proteolysis using food‐grade commercial enzymes (Alcalase®, Neutrase® and Protamex?). The release of oil under mild conditions (60°, 2 h) compared favourably with organic solvent extraction (19.8% vs. 21.5%). Lipids extracted by solvent and lipids resulting from enzymatic processes displayed a similar content of PUFA (about 35%), mainly eicosapentaenoic acid (EPA; 8.4% vs. 7.7%) and docosahexaenoic acid (DHA; 12.1% vs. 11.9%). Thin‐layer chromatography (TLC‐FID Iatroscan) showed that the polar lipid fraction accounted for 55% of total lipids (phosphatidylethanolamine, 20.7%; phosphatidylcholine, 14.8%). Salmon head phospholipids may be more effective carriers of highly unsaturated fatty acids to specific tissues than triacylglycerols, as shown by their content in EPA (10.3 and 6.9%, respectively) and DHA (33.1 and 9.1%, respectively).     

Lipid Profiles in By‐Products and Muscles of Three Shrimp Species (Penaeus monodon,Penaeus vannamei,and Penaeus chinensis)

To better understand the health benefits of lipids in shrimp and evaluate their potential value, a comprehensive analysis of lipid profiles in by‐products (head and body carapace) and muscles of shrimps Penaeus monodon, Penaeus vannamei, and Penaeus chinensis is performed. Results show that freeze‐dried muscles of these shrimps contain 3.83%, 4.39%, and 2.93% of lipids, respectively, while the corresponding by‐products contain 4.69%, 5.89%, and 5.39% of lipids, respectively. The total lipids comprise glycerophospholipid (PL, 54.86–77.29%), cholesterol (12.67–18.79%), triacylglycerol (1.28–7.02%), diacylglycerol (0.27–1.58%), monoacylglycerol (0.32–3.04%), and free fatty acid (FFA, 2.84–20.58%). Further, PL contains cholineglycerophospholipid (PLCho, 49.75–66.99 mol%), ethanolamineglycerophospholipid (PLEtn, 14.02–28.16 mol%), serineglycerophospholipid (PLSer, 4.85–12.66 mol%), inositolglycerophospholipid (PLIns, 4.36–15.63 mol%), and cholinelysoglycerophospholipid (LPLCho, 2.07–6.35 mol%). Lipids are abundant in polyunsaturated FA (36.55–42.72% of total FA), among which eicosapentaenoic acid (6.38–11.59% of total FA), and docosahexaenoic acid (7.63–12.08% of total FA) are dominant. About 200 species of PL belonging to PLCho, PLEtn, PLIns, LPLCho, lysoglycerophosphoethanolamine (LPLEtn), and lysoglycerophosphoserine (LPLSer) are characterized. Moreover, the by‐products contain higher amounts of astaxanthin than the muscles. Considering high level of PUFA enriched PL, shrimp by‐products can serve as a source for nutritional lipids. Practical Applications: This study presented a comprehensive analysis of the lipid profiles in by‐products (head and body carapace) and muscles of shrimps Penaeus monodon, Penaeus vannamei, and Penaeus chinensis. The results obtained justified the use of by‐products in shrimp processing, indicating that by‐products can be used for commercial exploitation and production of value‐added products due to PUFA‐enriched PL, especially EPA and DHA.     

Fatty Acid and Lipid Profiles with Emphasis on n-3 Fatty Acids and Phospholipids from Ciona intestinalis

In order to establish Ciona intestinalis as a new bioresource for n‐3 fatty acids‐rich marine lipids, the animal was fractionated into tunic and inner body tissues prior to lipid extraction. The lipids obtained were further classified into neutral lipids (NL), glycolipids (GL) and phospholipids (PL) followed by qualitative and quantitative analysis using GC‐FID, GC–MS, ¹H NMR, 2D NMR, MALDI‐TOF‐MS and LC–ESI–MS methods. It was found that the tunic and inner body tissues contained 3.42–4.08 % and 15.9–23.4 % of lipids respectively. PL was the dominant lipid class (42–60 %) irrespective of the anatomic fractions. From all lipid fractions and classes, the major fatty acids were 16:0, 18:1n‐9, C20:1n‐9, C20:5n‐3 (EPA) and C22:6n‐3 (DHA). The highest amounts of long chain n‐3 fatty acids, mainly EPA and DHA, were located in PL from both body fractions. Cholestanol and cholesterol were the dominant sterols together with noticeable amounts of stellasterol, 22 (Z)‐dehydrocholesterol and lathosterol. Several other identified and two yet unidentified sterols were observed for the first time from C. intestinalis. Different molecular species of phosphatidylcholine (34 species), sphingomyelin (2 species), phosphatidylethanolamine (2 species), phosphatidylserine (10 species), phosphatidylglycerol (9 species), ceramide (38 species) and lysophospholipid (5 species) were identified, representing the most systematic PL profiling knowledge so far for the animal. It could be concluded that C. intestinalis lipids should be a good alternative for fish oil with high contents of n‐3 fatty acids. The lipids would be more bioavailable due to the presence of the fatty acids being mainly in the form of PL.     

Season and Cooking May Alter Fatty Acids Profile of Polar Lipids from Blue-Back Fish

Polar lipids (PoL) represent a new promising dietary approach in the prevention and treatment of many human diseases, due to their potential nutritional value and unique biophysical properties. This study investigates the effects of catching season and oven baking on the fatty acid profiles (FAP) of PoL in four species of blue-back fish widely present in the North Adriatic Sea: anchovy (Engraulis encrasicholus), sardine (Sardina pilchardus), sprat (Sprattus sprattus), and horse mackerel (Trachurus trachurus). PoL levels (427–652 mg/100 g flesh) varied among the four species, with no significant seasonal variations within species. FAP of raw fillets were particularly high in polyunsaturated fatty acid (PUFA), especially docosahexaenoic acid (DHA) and EPA; total PUFA was constant in all species throughout the year, while long-chain n-3 polyunsaturated fatty acid (n-3 PUFA) rose in spring (except in sprat), especially due to the contribution of DHA. The FAP response for PoL to oven baking was species-specific and, among n-3 PUFA, DHA exhibited the greatest heat resistance; the influence of oven baking on FAP was found to be correlated with the catching season, especially for anchovy and sardine, while sprat PoL were not affected by cooking processes. The four species analyzed in this study presented very low n-6/n-3 fatty acid ratios and highly favorable nutritional indices, emphasizing their PoL qualities and promoting their role in increasing human n-3 PUFA intake. The four species can be considered as superior sources of n-3 PUFA and can be employed as supplements in functional food manufacturing and in pharmaceutical and cosmetic industries.     

Modulation of arachidonate and docosahexaenoate in Morone chrysops larval tissues and the effect on growth and survival

The extent to which extreme dietary levels of arachidonate (AA) and/pr docosahexaenoate (DHA) modulate lipid composition in the body tissues and consequently affect growth and survival in freshwater Morone larvae species was examined. White bass, M. chrysops, larvae (day 24–46) were fed Artemia nauplii enriched with algal oils containing varying proportions of AA and DHA (from 0 to over 20% the total fatty acids). Growth was significantly reduced (P<0.05) in larvae fed a DHA-deficient Artemia diet. Increases in dietary levels of AA also were associated with a significant growth reduction. However, the inhibitory effect of AA on larvae growth could be suppressed by the dietary addition of DHA (at a level of 21.6% of the total fatty acids in enrichment lipids). Larval brain+eyes tissue accumulated over 10 times more DHA than AA in its structural lipids (phosphatidylcholine, phosphatidylethanolamine) at any dietary ratio. In contrast, DHA accumulation, as compared to AA, in gill lipids declined considerably at higher than 10∶1 DHA/AA tissue ratios. DHA and eicosapentaenoic acid (EPA) contents in brain+eyes tissue were most sensitive to competition from dietary AA, being displaced from the tissue at rates of 0.36±0.07 mg DHA and 0.46±0.11 mg EPA per mg increase in tissue AA, and 0.55±0.14 mg AA per mg increase in tissue DHA. On the other hand, AA and EPA levels in gill tissue were most sensitive to dietary changes in DHA levels; AA was displaced at rates of 0.37±0.11 mg, whereas EPA increased at rates of 0.68±0.28 mg per mg increase in tissue DHA. Results suggest that balanced dietary DHA/AA ratios (that allow DHA/AA ratios of 2.5∶1 in brain+eyes tissue) promote a high larval growth rate, which also correlates with maximal regulatory response in tissue essential fatty acids.     

Effects of highly purified eicosapentaenoic acid and docosahexaenoic acid on fatty acid absorption, incorporation into serum phospholipids and postprandial triglyceridemia

Fourteen healthy volunteers were randomly allocated to receive 4 g highly purified ethyl esters of eicosapentaenoic acid (EPA) (95% pure, n=7) or docosahexaenoic acid (DHA) (90% pure, n=7) daily for 5 wk in supplement to their ordinary diet. The n−3 fatty acids were given with a standard high-fat meal at the beginning and the end of the supplementation period. EPA and DHA induced a similar incorporation into chylomicrons which peaked 6 h after the meal. The relative uptake of EPA and DHA from the meal was >90% compared with the uptake of oleic acid. During absorption, there was no significant elongation or retroconversion of EPA or DHA in total chylomicron fatty acids. The concentration of EPA decreased by 13% and DHA by 62% (P<0.001) between 6 and 8 h after the meal. During the 5-wk supplementation period, EPA showed a more rapid and comprehensive increase in serum phospholipids than did DHA. DHA was retroconverted to EPA, whereas EPA was elongated to docosapentaenoic acid (DPA). The postprandial triglyceridemia was suppressed by 19 and 49% after prolonged intake of EPA and DHA, respectively, indicating that prolonged intake of DHA is equivalent to or even more efficient than that of EPA in lowering postprandial triglyceridemia. This study indicates that there are metabolic differences between EPA and DHA which may have implications for the use of n−3 fatty acids in preventive and clinical medicine.     

Lipase‐catalysed enrichment of DHA and EPA in acylglycerols resulting from squid oil ethanolysis

The fatty acid specificity of four lipases towards eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) was evaluated when performing ethanolysis of squid oil. During the first part of ethanolysis, no DHA ethyl esters were detected when using the lipases from Thermomyces lanuginosus, Pseudomonas cepacia or Pseudomonas fluorescens (in the case of the second and third lipases, no EPA ethyl esters were detected either). This indicates that these three lipases could not catalyse the conversion of DHA located in a triacylglycerol to ethyl ester, and that the Pseudomonas lipases could not catalyse the conversion of EPA either. This pattern was not found for the lipase from Rhizomucor miehei. The lipase from Thermomyces lanuginosus showed the lowest specificity towards DHA and the highest DHA recovery during DHA enrichment in the acylglycerol fraction. It was thus used to catalyse the ethanolysis of squid oil on a larger scale. The ethyl esters formed were removed using short‐path distillation, resulting in a product containing mainly mono‐ and diacylglycerols. The product contained 34 mol‐% DHA and 17 mol‐% EPA, compared with 19 mol‐% DHA and 12 mol‐% EPA in the original squid oil.     

Fatty fish intake,n‐3 fatty acids and self‐rated health in middle‐aged adults

Background – Since n‐3 fatty acids, abundant in fatty fish, may improve health, we raised the question whether self‐reported intake frequency of fatty fish (FF) might be related to the percentage of n‐3 fatty acids in serum phospholipids (PL‐n‐3), and also to self‐rated health (H). Design – The study followed a cross‐sectional design. Methods – In the cross‐sectional Oslo Health Study, PL‐n‐3 were determined in 121 middle‐aged ethnic Norwegians and 102 immigrants from the Indian subcontinent and correlated with FF and H. Logistic regression was used to study the relationship between PL‐n‐3 and H (dichotomized, i.e. Poor vs. Good health). Results – FF correlated positively with PL20:5n‐3 (PL‐EPA, r = 0.467, p <0.001) and PL22:6n‐3 (PL‐DHA, r = 0.499, p <0.001), and negatively with PL20:4n‐6 (PL‐AA, r = –0.350, p = 0.001). H was positively associated with PL‐EPA (r = 0.321, p <0.001) and PL‐DHA (r = 0.275; p <0.001), but negatively with PL‐AA (r = –0.220, p = 0.001). The odds ratio for reporting Poor vs. Good health was significantly higher in subjects with low levels of PL‐EPA (OR = 1.49; 95% confidence interval = 1.17–1.89, p = 0.001), persisting after adjusting for sex, physical activity, ethnicity and length of education. Conclusion – The intake frequency of fatty fish is related to n‐3 fatty acids in the serum phospholipids, and to self‐rated health.     

Fatty Acids in Liver,Muscle and Gonad of three Tropical Rays including Non-Methylene-Interrupted Dienoic Fatty Acids

Scientific investigation of lipids in Elasmobranchs has been conducted mainly on shark species. Because rays seem to be neglected, this study was performed to examine the complete fatty acid (FA) composition with a particular interest for long-chain polyunsaturated FA (PUFA) content in different tissues of three ray species including parts usually discarded. The total FA and PUFA profiles of total lipids were determined in muscle, liver, and gonad of Rhinobatos cemiculus, Rhinoptera marginata, and Dasyatis marmorata, the most often caught ray species from the East Tropical Atlantic Ocean. Fifty FA were characterized as methyl esters and N-acyl pyrrolidides by gas chromatography/mass spectrometry, showing significant levels of 20:5n-3 (EPA) (up to 5.3%) and 22:5n-3 (DPA) (up to 7.3%), high levels of 20:4n-6 arachidonic (ARA) (4.8–8.6% of total FA) and 22:6n-3 (DHA) (up to 20.0%). The results show that muscle, liver and gonad of rays can provide high amounts of essential PUFA, specially DHA, for direct human nutrition or the food processing industry. High proportions of DHA were particularly found in all samples of R. cemiculus (11.6–20.0%), and in muscle and liver of D. marmorata (11.1–16.1%). Regarding the high amounts of (n-3) PUFA, this study shows that these rays deserve a better up-grading, including the normally discarded parts, and describes the occurrence of unusual NMID FA in all tissues studied. Five non-methylene-interrupted dienoic fatty acids (NMID FA) (0–3.4%) were reported, including previously known isomers, namely 20:2 Δ7,13, 20:2 Δ7,15, 22:2 Δ7,13, 22:2 Δ7,15, and new 22:2 Δ6,14. These acids are quite unusual in fish and unprecedented in rays. The 22:2 Δ6,14 acid occurred in gonads of male specimens of R. cemiculus at 2.9%.     

Lipid Profile and Glycerophospholipid Molecular Species in Two Species of Edible Razor Clams Sinonovacula constricta and Solen gouldi

Total lipids were extracted from razor clams Sinonovacula constricta and Solen gouldi, and the molecular species of glycerophospholipid (Gpl) including choline glycerophospholipid (ChoGpl), ethanolamine glycerophospholipid (EtnGpl), serine glycerophospholipid (SerGpl), inositol glycerophospholipid (InsGpl), lysoChoGpl, lysoEtnGpl, and lysoSerGpl were characterized using a direct-infusion tandem mass spectrometric method for the first time. Meanwhile, the lipid class composition and phospholipid (PL) class composition as well as the fatty acid (FA) composition of total lipids, triacylglycerol (TAG), and PL were also investigated. About 238 and 235 molecular species were characterized, respectively, in Sinonovacula constricta and Solen gouldi. The majority of the dominant Gpl molecular species contained n-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), especially docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Also, razor clam lipids contained a high-proportioned PL (52.19–65.41% of total lipids) and PUFA (47.94–54.81 mol%). Furthermore, PL contained a higher proportion of PUFA (63.05–67.13 mol%), especially DHA (20.04–22.47 mol%) and EPA (16.27–21.46 mol%) than TAG (the corresponding values being 33.73–34.45, 11.95–12.27, and 8.13–0.8.99 mol%, respectively). Meanwhile, phosphatidylcholine (44.38–46.21 mol%) and phosphatidylethanolamine (38.84–39.95 mol%) were dominant among PL. In consideration of the high proportion of PUFA-enriched Gpl, razor clam plays a great role in promoting human health.     

Biosynthesis of Long Chain Polyunsaturated Fatty Acids in the Marine Ichthyosporean Sphaeroforma arctica

Sphaeroforma arctica is a unique, recently discovered marine protist belonging to a group falling close to the yeast/animal border. S. arctica is found in cold environments, and accordingly has a fatty acid composition containing a high proportion of very long chain polyunsaturated fatty acids, including the ω3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexanoic acid (DHA). Two elongases and five desaturases, representing the complete set of enzymes necessary for the synthesis of DHA from oleic acid, were isolated from this species and characterized in yeast. One elongase showed high conversion rates on a wide range of 18 and 20 carbon substrates, and was capable of sequential elongation reactions. The second elongase had a strong preference for the 20-carbon fatty acids EPA and arachidonic acid, with over 80 % of EPA converted to docosapentaenoic acid (DPA) in the heterologous yeast host. The isolation of a Δ8-desaturase, along with the detection of eicosadienoic acid in S. arctica cultures indicated that this species uses the alternate Δ8-pathway for the synthesis of long-chain polyunsaturated fatty acids. S. arctica also carried a Δ4-desaturase that proved to be very active in the production of DHA from DPA. Finally, a long chain acyl-CoA synthetase from S. arctica improved DHA uptake in the heterologous yeast host and led to an improvement in desaturation and elongation efficiencies.     

Fatty Acid Composition and Contents of Seven Commercial Fish Species of Genus <Emphasis Type="Italic">Coregonus</Emphasis> from Russian Subarctic Water Bodies

In several Russian northern lakes and rivers, Arctic cisco Coregonus autumnalis, least cisco C. sardinella, peled C. peled, tugun C. tugun, broad whitefish C. nasus, whitefish C. lavaretus and vendace C. albula were sampled in periods of officially permitted commercial fishery. Special attention was paid to contents (mg g^?1 of wet weight) of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) in muscle tissues (filets), which are essential for human nutrition. The highest values of EPA + DHA content in semi‐anadromous fish and freshwater fish were recorded for C. autumnalis from the Yenisei River, 17.60 mg g^?1 wet weight, and for C. lavaretus from the Sobachye Lake, 16.61 mg g^?1 wet weight, respectively. Intra‐genus variations of EPA + DHA contents of Coregonus species were from 1.87 to 17.60 mg g^?1 wet weight. Since the congeneric species were genetically close to each other, the variations in EPA and DHA contents were thought to be caused primarily by ecological factors: migrational capability, type of feeding and trophic status of aquatic ecosystems. In general, the majority of studied species appeared to be of a high nutritive value for humans, although unfavorable environmental conditions could considerably diminish this value.     

Comparison between extraction of lipids and fatty acids from microalgal biomass

Seven solvent mixtures have been used to extract the lipid fraction of lyophilized biomass ofIsochrysis galbana. Six of them were composed of biocompatible solvents. Each method was carried out under relaxed operating conditions (i.e., one hour at room temperature) with extraction in a nitrogen atmosphere to prevent autooxidation and degradation of polyunsaturated fatty acids (PUFAs). Apart from the well-established Bligh and Dyer method [Can. J. Biochem. Physiol. 37:911 (1959)] (Cl₃CH/MeOH/H₂O, 1∶2∶0.8, vol/vol/vol), which rendered the highest yield of lipids (93.8%), ethanol (96%) and hexane/ethanol (96%), 1∶2.5 vol/vol produced the best results (84.4 and 79.6%, respectively). To obtain free fatty acids, KOH was added to the solvent mixtures used to extract the total lipids, except for Cl₃CH/MeOH/H₂O, and direct saponification was carried out at 60°C for 1 h or at room temperature for 8 h. The highest yields obtained by direct saponicification were 81% with hexane/ethanol (96%), 1∶2.5, vol/vol and 79.8% with ethanol (96%). Partial yields of the mainn-3 PUFAs found inI. galbana, stearidonic acid (SA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were calculated for both extraction methods. For lipid extraction with ethanol (96%), yields of 91, 82 and 83% were obtained for SA, EPA and DHA, respectively. When direct saponification was used, hexane/ethanol (96%; 1∶2.5, vol/vol) produced the best yields of (91, 79 and 69% for SA, EPA and DHA, respectively).     

Wax Ester Rich Oil From The Marine Crustacean,Calanus finmarchicus,is a Bioavailable Source of EPA and DHA for Human Consumption

Oil from the marine copepod, Calanus finmarchicus, which contains >86 % of fatty acids present as wax esters, is a novel source of n‐3 fatty acids for human consumption. In a randomized, two‐period crossover study, 18 healthy adults consumed 8 capsules providing 4 g of Calanus^® Oil supplying a total of 260 mg EPA and 156 mg DHA primarily as wax esters, or 1 capsule of Lovaza^® providing 465 mg EPA and 375 mg DHA as ethyl esters, each with an EPA‐ and DHA‐free breakfast. Plasma EPA and DHA were measured over a 72 h period (t = 1, 2, 4, 6, 8, 10, 12, 24, 48, and 72 h). The positive incremental area under the curve over the 72 h test period (iAUC_{0‐72 h}) for both EPA and DHA was significantly different from zero (p < 0.0001) in both test conditions, with similar findings for the iAUC_{0–24 h} and iAUC_{0–48 h}, indicating the fatty acids were absorbed. There was no difference in the plasma iAUC_{0–72 h} for EPA + DHA, or DHA individually, in response to Calanus Oil vs the ethyl ester condition; however, the iAUC_{0–48 h} and iAUC_{0–72 h} for plasma EPA in response to Calanus Oil were both significantly increased relative to the ethyl ester condition (iAUC_{0–48 h}: 381 ± 31 vs 259 ± 39 μg*h/mL, p = 0.026; iAUC_{0‐72 h}: 514 ± 47 vs 313 ± 49 μg*h/mL, p = 0.009). These data demonstrate a novel wax ester rich marine oil is a suitable alternative source of EPA and DHA for human consumption.