Lipids in the daubed shanny (Teleostei: Leptoclinus maculatus) in Svalbard waters

The daubed shanny, Leptoclinus maculatus, is a common fish species in Arctic and North Atlantic waters and has an important role in high-latitude ecosystems as a link between lower trophic levels and many fish, marine mammal and seabird species. Its biology and ecology have, however, remained largely unstudied. The primary aim of this study was to increase the knowledge about the daubed shanny by analysing total lipids, lipid-classes and the fatty acid composition of liver, muscle and female gonads in adults from the high Arctic archipelago of Svalbard. In female gonads, the triacylglycerols and wax esters in addition to cholesterol esters were dominant among the stored lipids. Triacylglycerols dominated in the liver, whereas structural lipids, such as phospholipids and cholesterols, were the most important lipids in muscles. Phosphatidylcholine and phosphatidylethanolamine were major phospholipids in all organs studied. The fatty acid spectrum of the investigated organs was characterized by a high amount of monounsaturated fatty acids, particularly in the liver. Polyunsaturated fatty acids, particularly 22:6(n-3) and 20:4(n-6), were prevalent in muscle tissues. The lipid and fatty acid spectra in the organs during this period of life are tightly connected with the activation of the liver metabolism and the storage of lipids in the developed female gonads. Lipid accumulation and distribution in gonads are transferred to optimal development of embryos and larvae in Arctic waters.     

The reproduction strategy of oyster ostrea edulis L. from the biochemical point of view

• 1.1. Influence of the biochemical composition of food (four species of micro-algae and one mixture) on the biochemical composition of gonads and larvae of O. edulis (total protein, lipid, carbohydrate, ash content, neutral and polar lipid class composition, amino acid composition and fatty acid composition of total, neutral and polar lipids) and the size of newly released larvae have been investigated.
• 2.2. Precentage of total lipids and triacylglycerols in gonads depends on that in algae (r = 0.52 and 0.69 accordingly).
• 3.3. Gonads rich in lipids had a higher level of triacylglycerols, phospholipids, polar lipids and a lower value of the ratio phosphatidylethanolamine/phosphatidylcholine (PE/PC) than gonads with a low lipid content.
• 4.4. Amino acid composition of gonads depends on that of food, in this case, essential acids are preferentially accumulated (Asp acid, Ser, Ala, Cys, Tyr and Pro) and two non-essential (Thr and Lys).
• 5.5. Fatty acid composition of total lipids of gonads was rather stable; except for the two essential acids 20:523 and 22:6w3, their percentage depends on that of food r = 0.65 and 0.65 accordingly). Fatty acid composition of neutral lipids was more diverse (in number and degree of variety) as compared to polar lipids.
• 6.6. Larvae released from oysters with gonads rich in lipids had a higher percentage of lipids, triacylglycerols, size and a lower ash percentage and value of ratio PE/PC, as compared to larvae from gonads with low lipid content. Total lipid and triacylglycerol contents in gonads correlate rather well with those in larvae (r = 0.77 and 0.47 accordingly).
• 7.7. Phospholipid class composition of larvae strongly depends on that of gonads. All the correlations are high and positive in character (except for phosphatidylinositol).
• 8.8. Amino acid composition of larvae depends on that of gonads and, as in the case with gonads, the same essential acids are accumulated in the first place.
• 9.9. Fatty acid composition of total lipids of newly released larvae was rather stable and independent on that of gonads except for total polyunsaturated acids (r = 0.70) and 20:5w3 (r = 0.65). Fatty acid composition of neutral lipids was lesser diverse (in number and degree of variation) as compared to polar lipids.

     

Comparison of growth and lipid composition in the green abalone, Haliotis fulgens, provided specific macroalgal diets

Lipid composition of abalone was examined over a one-year interval. A feeding trial was designed to cover a full reproductive cycle in young adult green abalone, Haliotis fulgens, consisting of five diet treatments: the macrophytic algal phaeophyte Egregia menziesii, rhodophyte Chondracanthus canaliculatus, chlorophyte Ulva lobata, a composite of the three algae and a starvation control. The lipid class, fatty acid, sterol and 1-O-alkyl glyceryl ether profiles were determined for foot, hepatopancreas/gonad tissues and larvae. The major fatty acids were 16:0, 18:0, 18:1(n-7)c, 18:1(n-9)c, 20:4(n-6), 20:5(n-3) and 22:5(n-3), as well as 14:0 for abalone fed brown and red algae. 4,8,12-Trimethyltridecanoic acid, derived from algae, was detected for the first time in H. fulgens (hepatopancreas complex, 1.2–13.9%; larvae, 0.5% of total fatty acids). Diacylglyceryl ethers were present in larvae (0.6% of total lipid). The major 1-O-alkyl glycerols were 16:0, 16:1 and 18:0. Additionally, 18:1(n-9) was a major component in hepatopancreas/gonad and larvae. The major sterol was cholesterol (96–100% of total sterols). Highest growth rates were linked to temperature and occurred in abalone fed the phaeophyte E. menziesii (43 μm·day^–1, 56 mg·day^–1 yearly mean), an alga containing the highest levels of C₂₀ polyunsaturated fatty acids and the highest ratio of 20:4(n-6) to 20:5(n-3). This study provides evidence of the influence of diet and temperature on seasonal changes in abalone lipid profiles, where diet is most strongly related to body mass and temperature to shell length. The allocation of lipids to specific tissues in green abalone clarifies their lipid metabolism. These results provide a basis for improving nutrition of abalone in mariculture through formulation of artificial feeds.     

Lipids and fatty acids in the copepod Jaschnovia brevis (Jaschnov) and in particulates from Arctic waters

The small, sub-ice copepod Jaschnovia brevis is rich in triacylglycerols, suggesting a feeding behaviour not constrained to the seasonal phytoplankton bloom. The copepod's triacylglycerol reserves contain: the diatom biomarkers 16:1n-7 (23.9%), 20:5n-3 (8.5%) and C16 PUFA (1.3%), the flagellate biomarkers 18:4n-3 (3.7%) and 22:6n-3 (3.3%), and the Calanus copepod biomarkers 20:1n-9 (7.7%) and 22:1n-11 (6.2%). Total lipid from particulates in the water column contained polar lipid (45.0%), wax esters (24.9%) and triacylglycerols (11.2%) as major components. The total lipids in the particulates were rich in 18:1n-9 (31.5%) and 16:0 (21.2%), and relatively rich in 18:0 (7.8%) and 18:2n-6 (9.2%). The triacylglycerols in the particulates contained 16:1n-7 (20.7%), C16 PUFA (4.1%), 18:4n-3 (1.9%), 20:5n-3 (3.6%), 22:6n-3 (1.9%), 20:1n-9 (5.2%) and 22:1n-11 (3.9%). The polar lipids in the particulates contained 16:1n-7 (17.3%), C16 PUFA (7.8%), 18:4n-3 (3.3%), 20:5n-3 (14.5%) and 22:6n-3 (9.6%). The fatty alcohols in the wax esters of the particulates were mainly 16:0 (11.3%), 20:1n-9 (21.1%) and 22:1n-11 (30.6%). The nature of the particulates, their possible origin in living and non-living material, and their role in the nutrition of J. brevis are discussed.     

Uptake,incorporation and calcium-ionophore-stimulated mobilization of arachidonic,eicosapentaenoic and docosahexaenoic acids by leucocytes of the rainbow trout,Salmo gairdneri

Rainbow trout leucocytes contain high levels of neutral lipid (about 70% of total lipid on a wt% basis) consisting of mostly triacylglycerol, free sterols and sterol esters (25%, 15% and 52% of neutral lipid, respectively). The phospholipids, separated by thin-layer chromatography, consisted predominantly of phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine, each present at about 30% of the total phospholipid. Radiolabelling of the leucocytes for 1 h with 1 μCi (approx. 6 μM) [1−¹⁴C]20:4(n−6), [1−¹⁴C]20:5(n−3) or [1−¹⁴C]22:6(n−3) each gave similar uptake values (approx. 1 · 10⁵ cpm/10⁷ leucocytes). The incorporation into total phospholipids was highest for 22:6(n−3) and lowest for 20:4(n−6). A higher percentage of radiolabel from [1−¹⁴C]22:6(n − 3) was found incorporated into phosphatidylcholine and phosphatidylethanolamine as compared to that from [1−¹⁴C]20:4(n − 6) and [1−^14C]20:5(n−3), while the reverse situation was found with phosphatidylinositol and phosphatidylserine. The relative rates of incorporation into the different phospholipid classes for all three fatty acids were in the order phosphatidylinositol > sphingomyelin > diphosphatidylglycerol > phosphatidylcholine > phosphatidylethanolamine > phosphatidylserine. Calcium ionophore-challenge did not significantly alter the pattern of phospholipid radiolabel. Ionophore-challenge released large amounts of radiolabel, much of which was recovered after high-performance liquid chromatographic separation as free fatty acid/monohydroxy fatty acids, although only approx. 0.3% was recovered in leukotriene B₄ and leukotriene B₅ for the [1−¹⁴C]20:4(n−6) and [1−¹⁴C]20:5(n−3) labelled leucocytes, respectively. Other lipoxygenase products were also radiolabelled and tentatively identified as 20-carboxy-LTB₄, 20-hydroxy-LTB₄, 6-trans-LTB₄, 6-trans-12-epi-LTB₄, 6-trans-8-cis-12-epi-LTB₄ and the corresponding LTB₅ structures. No ‘6-series’ leukotrienes were produced from [1−¹⁴C]22:6(n−3), nor was there any evidence for the synthesis of ‘5-series’ leukotrienes via retroconversion of 22:6(n−3) to 20:5(n−3). This latter finding shows that, despite the preponderance of 22:6(n−3) in the membranes of trout leucocytes, this fatty acid is not a substrate for leukotriene generation.     

Lipid, fatty acid and protein utilization during lecithotrophic larval development of Lithodes santolla (Molina) and Paralomis granulosa (Jacquinot)

During the larval development of the subantarctic king crab, Lithodes santolla, and stone crab, Paralomis granulosa, we compared changes in the carbon, fatty acid and protein contents of larvae reared under constant conditions from hatching to metamorphosis, either in presence or absence of food (Artemia spp. nauplii). In both species the feeding condition had no influence on any of the chemical parameters studied, indicating a fully lecithotrophic (i.e. non-feeding) mode of development from hatching of the first zoea to metamorphosis of the late megalopa. Dry mass and carbon contents at hatching were similar in the larvae of both species, but L. santolla contained initially higher total amounts of fatty acids and protein than P. granulosa. Both species utilized considerable portions of their total fatty acid pool which decreased logarithmically throughout the time of development. At metamorphosis, it was almost exhausted in P. granulosa, while L. santolla had consumed only about 60%. Protein utilization, in contrast, was higher in L. santolla (40%) than in P. granulosa (20%). Triacylglycerol was the principal storage lipid in both species, accounting initially for about 75% of the lipid fraction; it was strongly utilized during larval development. Phospholipid constituted the second largest lipid class; it also decreased in P. granulosa, but to a lesser extent in L. santolla. The major fatty acids of both species were 18:1(n−9), 20:5(n−3) and 16:0 as well as, in lower proportions, 18:1(n−7), 22:6(n−3), 16:1(n−7) and 18:0. Monounsaturated fatty acids represented the dominant group in L. santolla, whereas P. granulosa contained similar amounts of mono- and polyunsaturated fatty acids. In L. santolla, monounsaturated fatty acids, especially 16:1(n−7), were preferentially utilized as compared to polyunsaturates. Due to a particularly strong lipid utilization in P. granulosa, all individual fatty acids were largely depleted at metamorphosis, showing similar extents of consumption. L. santolla had higher initial lipid and protein stores that seem to be used more economically as compared to P. granulosa.     

Lipid content and composition of the Antarctic lamellibranch, Laternula elliptica (King & Broderip) (Anomalodesmata: Laternulidae), in King George Island during an austral summer

Total lipid content, lipid classes and fatty acid composition were studied in various tissues of the Antarctic clam Laternula elliptica in an early austral summer. A histological examination of the gonads revealed that most of the clams examined were spawning or ready to spawn. Lipid content was highest in gills (14.9% of tissue dry weight), followed by gonads (10.9%) and digestive glands (9.9%), and averaged 8.2% for the soft tissues. The overall lipid contents were relatively low compared to temperate bivalves at a similar reproductive stage. Lipid class composition in the total lipid of L. elliptica was quite similar to those of most marine bivalves at lower latitudes, being dominated by triacylglycerols (19.3–41.4% of total lipids) and phospholipids (18.9–28.3%) in most of the organs. Large amounts of triacylglycerol deposits in non-reproductive tissues, particularly in siphon and gill, indicate a potential role of lipid as maintenance energy reserve, although the low lipid contents suggest that lipid may not serve as an energy reserve for any food-limited periods. Fatty acid composition in L. elliptica was also typical of marine bivalves with predominance of 16:0 (26%) and 20:5n-3 (18%) acids. Total fatty acids from the soft tissues showed a moderate level of unsaturation (50.6%), and about 35% of the total fatty acids were polyunsaturated. These values were not significantly different from, or even lower than those of marine bivalves in warmer waters. However, the content of 20:5n-3 (18.2% of total fatty acids), which dominated n-3 polyunsaturated fatty acids, was similar to those reported for other marine bivalve species in temperate waters. The fatty acid composition of L. elliptica reflected dietary input of some microalgal species. The nanoflagellates Cryptomonas spp., which were reportedly rich in 16:0, 18:3n-3 and 20:5n-3, predominated in the water column during the present investigation. Accepted: 19 June 1999     

Gamma-linolenic acid alters the composition of mitochondrial membrane subfractions,decreases outer mitochondrial membrane binding of hexokinase and alters carnitine palmitoyltransferase I properties in the Walker 256 rat tumour

Gamma-linolenic acid (GLA) is known to be an inhibitor of Walker 256 tumour growth in vivo and causes changes in both mitochondrial structure and cellular metabolism. The aim of the present study was to investigate in greater detail the changes in energy metabolism and ultrastructure induced by GLA in this tumour model. A diet containing 5.5% GLA, which is sufficient to cause a 45% decrease in tumour growth, was found to almost double the triacylglycerol (TAG) content of the tumour and to increase the quantity of 20:3 n?6, 20:4 n?6, 22:4 n?6 and 22:5 n?6 in the TAG fraction as determined by gas chromatography–mass spectrometry (GCMS) analysis. Morphometric analysis of the tumour by electron microscopy confirmed this increase in TAG content, identifying a doubling of lipid droplet content in the GLA dietary group. The surface density of mitochondrial cristae was reduced, along with a reduction in the number of contact sites (CS) and matrix granules. These three parameters are likely indicators of a reduction in mitochondrial metabolic activity. Measurement of hexokinase activity identified that much of the total hexokinase activity was in the mitochondrially bound form (66.5%) in the control tumour and that GLA caused a decrease in the amount of enzyme in the bound form (39.3%). The fatty acyl chain composition of the tumour mitochondrial subfractions, outer membranes (OM), CSs and inner membranes (IM) was determined by GCMS. All subfractions showed considerable increases in 20:3 n?6 and decreases in 18:1 n?9, 18:2 n?6 and 22:6 n?3, when exposed to GLA diet. These changes were reflected in a large increase in the n?6/n?3 ratio in the GLA OM vs. the control OM, 21.299 vs. 6.747, respectively. The maximal activity of OM carnitine palmitoyltransferase I (CPT I) was found to be decreased by 61.6% in the GLA diet group. This was accompanied by a decrease in malonyl CoA sensitivity and a decrease in affinity for 16:0 CoA substrate. Such changes in CPT I may be the cause of cytoplasmic acyl CoA accumulation seen in this tumour model. These effects, together with previously reported increases in lipid peroxidation, lead to the conclusion that GLA may cause inhibition of tumour cell growth through separate but interlinked pathways, all of which eventually lead to apoptosis and a decrease in tumour development. The influence of mitochondrial OM fatty acyl chain composition upon two important enzymes of energy metabolism, hexokinase and CPT I, both of which have been linked to apoptosis, is of considerable importance for future studies on fatty acid-induced cell death.     

The desaturation and elongation of linolenic acid and eicosapentaenoic acid by hepatocytes and liver microsomes from rainbow trout (Oncorhynchus mykiss) fed diets containing fish oil or olive oil

The products of desaturation and elongation of [1−¹⁴C] 18:3(n − 3) and [1−¹⁴C]20:5(n − 3) were studied using hepatocytes and microsomes prepared from livers of trout maintained on diets containing either olive oil or fish oil, to establish the extent to which the formation of 22:6(n − 3) was enhanced in the absence of dietary 22:6(n − 3) and to investigate the pathway(s) of conversion of 18:3(n − 3) and 20:5(n − 3) to 22:6(n − 3). Levels of 20:5(n − 3) and 22:6(n − 3) in the total lipid of hepatocytes from trout fed olive oil were 20-fold and 10-fold, respectively, lower than in cells from trout fed fish oil. For both dietary groups, [1−¹⁴C]18:3(n − 3) was incorporated into hepatocyte lipid to a greater extent than [1−¹⁴C]20:5(n − 3). Almost 70% of the total radioactivity from [1−¹⁴C]18:3(n − 3) was recovered in hepatocyte triacylglycerols, whereas radioactivity from [1−¹⁴C]20:5(n − 3) was recovered almost equally in neutral lipids (52%) and polar lipids (48%). The products of desaturation and elongation from both labelled substrates were esterified mainly into hepatocyte polar lipids, whereas elongation products of [1−¹⁴C]18:3(n − 3) were preferentially incorporated into neutral lipids. Radioactivity recovered in the 22:6(n − 3) of polar lipids of hepatocytes from trout fed olive oil, from both ¹⁴C substrates, was approximately double that in hepatocytes from trout fed fish oil. No radioactivity from either [1−¹⁴C]18:3(n − 3) or [1−¹⁴C]20:5(n − 3) was incorporated into 22:6(n − 3) by microsomes isolated from livers from either group of fish and incubated in the presence of acetyl-CoA, malonyl-CoA, NADH, NADPH, ATP and coenzyme A. However, significant radioactivity was recovered in 24:5(n − 3) and 24:6(n − 3) from [1−¹⁴C]20:5(n − 3) and more radioactive 24:6(n − 3) accumulated in microsomes from trout fed olive oil than from trout fed fish oil. The results establish that the formation of 22:6(n − 3) from both 18:3(n − 3) and 20:5(n − 3) in hepatocytes of rainbow trout is stimulated by omitting 22:6(n − 3) from the diet and are consistent with the biosynthesis of 22:6(n − 3) in trout liver cells proceeding via 24:5(n − 3) and 24:6(n − 3) intermediates.     

Purification of fatty acid methyl esters by high-performance liquid chromatography

The determination by gas chromatography (GC) of fatty acid methyl esters (FAMEs) prepared from complex biological samples is subject to interference from cholesterol. During sample injection on the GC system of FAMEs prepared from tissues that contain cholesterol, we observed a major contaminant that co-eluted with docosahexaenoic acid (DHA, 22:6n-3). To address this problem, FAMEs were purified on an amino-phase high-performance liquid chromatography (HPLC) column using a hexane–isopropanol gradient. The HPLC retention times for both the FAME fraction and cholesterol were stable and reproducible when the amino column was used for sample purification. The purified extracts were analyzed by GC without artifacts or impurity peaks after 50 analytical runs. The method described here will be useful for measurement of 22:6n-3 and other fatty acids important for studies of nutrition or pathology.     

The pathway from arachidonic to docosapentaenoic acid (20:4n-6 to 22:5n-6) and from eicosapentaenoic to docosahexaenoic acid (20:5n-3 to 22:6n-3) studied in testicular cells from immature rats

The concentration-dependent metabolism of 1-¹⁴C-labelled precursors of 22:5n-6 and 22:6n-3 was compared in rat testis cells. The amounts of [¹⁴C]22- and 24-carbon metabolites were measured by HPLC. The conversion of [1-¹⁴C]20:5n-3 to [3-¹⁴C]22:6n-3 was more efficient than that of [1-¹⁴C]20:4n-6 to [3-¹⁴C]22:5n-6. At low substrate concentration (4 μM) it was 3.4 times more efficient, reduced to 2.3 times at high substrate concentration (40 μM). The conversion of [1-¹⁴C]22:5n-3 to [1-¹⁴C]22:6n-3 was 1.7 times more efficient than that of [1-¹⁴C]22:4n-6 to [1-¹⁴C]22:5n-6 using a low, but almost equally efficient using a high substrate concentration. When unlabelled 20:5n-3 was added to a cell suspension incubated with [1-¹⁴C]20:4n-6 or unlabelled 22:5n-3 to a cell suspension incubated with [1-¹⁴C]22:4n-6, the unlabelled n-3 fatty acids strongly inhibited the conversion of [1-¹⁴C]20:4n-6 or [1-¹⁴C]22:4n-6 to [¹⁴C]22:5n-6. In the reciprocal experiment, unlabelled 20:4n-6 and 22:4n-6 only weakly inhibited the conversion of [1-¹⁴C]20:5n-3 and [1-¹⁴C]22:5n-3 to [¹⁴C]22:6n-3. The results indicate that if both n-6 and n-3 fatty acids are present, the n-3 fatty acids are preferred over the n-6 fatty acids in the elongation from 20- to 22- and from 22- to 24-carbon atom fatty acids. In vivo the demand for 22-carbon fatty acids for spermatogenesis in the rat may exceed the supply of n-3 precursors and thus facilitate the formation of 22:5n-6 from the more abundant n-6 precursors.     

Lipid biomarkers indicate different ecological niches and trophic relationships of the Arctic hyperiid amphipods Themisto abyssorum and T. libellula

The hyperiid amphipods Themisto libellula and T. abyssorum are important components of Arctic pelagic ecosystems. Both species are carnivorous and prey on mesozooplankton. They represent a substantial food source for marine vertebrates and are a key link between zooplankton secondary production and higher trophic levels. We present data on the total lipid content, lipid class and fatty acid composition of T. libellula and T. abyssorum from northern Fram Strait and the central Arctic Ocean. Both species had moderate to high lipid contents of 14-42% of body dry mass. In T. abyssorum, total lipid content was correlated to body mass, while T. libellula showed sex-related differences in lipid content. Despite their smaller body size, females of T. libellula had higher lipid contents than males. Wax esters represented the major lipid class in both species with 41-43% of total lipid, while triacylglycerols contributed 23-32%. The fatty acid composition was dominated by the long-chain polyunsaturated moieties 20:5(n-3) and 22:6(n-3), short-chain saturated compounds (16:0 and 14:0) and monounsaturated fatty acids of varying length, i.e. 16:1(n-7), 20:1(n-9), 18:1(n-9) and 22:1(n-11). Species-specific and geographic variations in the fatty acid and alcohol patterns were apparently linked to differences in diet and life-cycle. High amounts of the fatty acids and alcohols 20:1(n-9) and 22:1(n-11) in T. libellula indicate predation on herbivorous Calanus copepodids. In addition, elevated levels of 20:5(n-3) in T. libellula indicate a close connection with ice-algal production and the importance of cryo-pelagic coupling processes (i.e. exchange processes between the sea ice and the pelagic communities) for the nutrition of this high-Arctic epipelagic species. In contrast, T. abyssorum is characterised by lower amounts of 20:5(n-3) and its biomarker ratios indicate a higher trophic level. This observation is consistent with the subarctic-boreal origin of T. abyssorum and its occurrence in deeper layers of the Arctic Ocean, where it may feed on omnivorous and/or carnivorous prey.     

Nutritional and bioactive properties of three edible species of green algae,genus Caulerpa (Caulerpaceae)

The green algae genus Caulerpa is coenocytic, and the thallus consists of only one cell with many nuclei. It is widely distributed in the tropical seas. In the Southeast Asian waters, there are at least ten known species. Three species, particularly Caulerpa racemosa var. clavifera f. macrophysa (Kützing) Weber-van Bosse, C. racemosa var. laetevirens (Montagne) Weber-van Bosse, and Caulerpa lentillifera J. Agardh are widely consumed. The proximate analysis and secondary metabolite composition of these three species were determined to describe their lipid and nutritional values. Glycolipids and phospholipids were the major lipid classes, with significant levels of triacylglycerol. Polyunsaturated fatty acids (PUFA) were the major fatty acids of all the three species. Typical n-3 and n-6 PUFA such as 18:3n-3, 18:4n-3, 20:5n-3, 18;2n-6, and 20:4n-6 were found in significant amount in all these three species. All three species contained a red-pigmented secondary metabolite determined as caulerpin. All three extracts exhibited potent antimicrobial activity against human food pathogenic bacteria and anti-inflammatory activity against the murine macrophage cell line, RAW 264.7.     

DHA status of vegetarians

The aim of the present study was to evaluate the influence of pregnancy in adolescents on the fatty acid composition of the erythrocyte membrane, which was used as a proxy for status of n-3 and n-6 polyunsaturated fatty acids (PUFA), and also on the composition of plasma non-esterified fatty acids (NEFA) mobilized from the adipose tissue. Two matched groups of healthy adolescents (14–19 years) from Rio de Janeiro, Brazil, were compared: pregnant (n=26; 32.7±3.9 weeks of gestation, mean±SD) and non-pregnant (n=20). Blood samples were collected after an overnight fast. Mean dietary intakes of total fat and n-3 and n-6 PUFA (energy %) were not different between pregnant and non-pregnant adolescents, and the consumption of food sources of docosahexaenoic acid (DHA) was low. Fasting total NEFA and NEFA 18:2n-6, 18:3n-6 and 20:4n-6 (g/100 g fatty acids) were higher in pregnant than in non-pregnant adolescents. Although erythrocyte 20:4n-6 was lower in pregnant adolescents, there were no differences in DHA (g/100 g fatty acids), in DHA status indices (22:5n-6/22:4n-6 and 22:6n-3/22:5n-6 ratios) and in the index of n-3+n-6 PUFA status ([Σn-3+Σn-6]/[Σn-7+Σn-9]) in erythrocytes as compared with those of non-pregnant adolescents. In conclusion, pregnancy did not have an adverse effect on erythrocyte DHA content or on DHA and n-3+n-6 PUFA status indices in the adolescents studied.     

Fatty acid biomarker ratios—suitable trophic indicators in Antarctic euphausiids?

Fatty-acid biomarkers are frequently used for the identification of trophic relationships among marine zooplankton. We have evaluated the suitability of five fatty-acid ratios [16:0/16:1(n-7), 16:1(n-7)/18:4(n-3), 18:1(n-9)/18:1(n-7), 20:5(n-3)/22:6(n-3), PUFA/SFA] that have been proposed as trophic indicators in the literature. Total lipid content and fatty-acid composition were determined in four Antarctic euphausiid species (Euphausia superba, E. frigida, E. triacantha, Thysanoessa macrura). There is a significant relationship between the lipid content and most of these ratios in the investigated euphausiids. Only the 16:1(n-7)/18:4(n-3) ratio exhibits no clear relationship to total lipids. Further exceptions occur in E. triacantha: the 18:1(n-9)/18:1(n-7) and the 20:5(n-3)/22:6(n-3) ratios are not correlated to the lipid content in this species. There is a weaker correlation between the fatty-acid ratios and the total lipid content in E. superba larvae than in the postlarvae, indicating a stronger dietary influence on the lipids of the younger stages. We conclude that those fatty-acid ratios that strongly depend on an animals total lipid content (particularly PUFA/SFA), are only of limited use as trophic indices, since total lipid content may vary greatly with factors (such as reproductive processes) that are unrelated to specific feeding preferences.     

Differences in growth,total lipid content and fatty acid composition among 60 clones of <Emphasis Type="Italic">Cylindrotheca fusiformis</Emphasis>

Differences between clones of the diatom Cylindrotheca fusiformi were studied with respect to growth rate, total lipid content and fatty acid composition. Sixty clones were isolated and cultivated under batch conditions. All clones were grown under identical conditions (temperature 22±1°C, light intensity 100 μmol photon m⁻² s⁻¹, salinity 28, F/2 medium) and were harvested in the late exponential growth phase for lipid and fatty acid analysis. The results show a wide variation in growth, total lipid content and fatty acid profiles among clones (p<0.05). The major fatty acids in the 60 clones were 14:0 (4.6–9.1%), 16:0 (18.2–32.0%), 16:1n-7 (21.6–33.1%), 20:4n-6 (4.1–13.5%) and 20:5n-3 (6.2–17.2%), with the highest proportion of 20:4n-6 in clone CF13 (13.5%), and the highest proportion of 20:5n-3 in clone CF5 (17.2%). The results support the view that some microalgal fatty acid variation is not restricted to interspecific variation and external factors, but also varies from clone to clone within the same species.     

Functional Characterization of Polyunsaturated Fatty Acid Delta 6-Desaturase and Elongase Genes from the Black Seabream (Acanthopagrus schlegelii)

Fatty acid delta 6-desaturase (D6DES) and elongases are key enzymes in the synthesis of polyunsaturated fatty acids (PUFAs) including arachidonic acid (ARA) and eicosapentaenoic acid (EPA) from microorganisms to higher animals. To identify the genes encoding D6DES and elongases for PUFAs, we isolated each cDNA with a high similarity to the D6DES and ELOVL5-like elongases of mammals and fishes via degenerate PCR and RACE-PCR from Acanthopagrus schlegelii. A recombinant vector expressing AsD6DES was subsequently constructed and transformed into Saccharomyces cerevisiae to test the enzymatic activity toward n-6 and n-3 fatty acids in the PUFA biosynthesis. The heterologously expressed AsD6DES produced γ-linolenic acid (GLA, C_18:3 n-6) and stearidonic acid (STA, C_18:4 n-3) at conversion rates of 26.3–35.6 % from exogenous linoleic acid (LA, C_18:2 n-6) and α-linolenic acid (ALA, C_18:3 n-3) substrates, respectively. When AsELOVL5 was expressed in yeast, it conferred an ability to elongate GLA to di-homo-γ-linolenic acid (DGLA, C_20:3 n-6). In addition, AsELOVL5 showed an ability to convert ARA (C_20:4 n-6) and EPA (C_20:5 n-3) to dodecylthioacetic acid (DTA, C_22:4 n-6) and docosapentaenoic acid (DPA, C_22:5 n-3), respectively. In these results, the AsD6DES encodes a delta 6-fatty acid desaturase and the AsELOVL5 encoding a long-chain fatty acid elongase shows activity to enlongate C₁₈Δ6/C₂₀Δ5, but not C₂₂.     

Effect of varying levels of dietary essential fatty acid during early ontogeny of the sea scallop Placopecten magellanicus

This study investigated the biological effects of various dietary essential fatty acids levels to sea scallop larvae, Placopecten magellanicus. Scallop larvae were fed three diets from D-veliger to settlement. Diet A consisted of Isochrysis sp. and Pavlova lutheri, diet B was a mix of Isochrysis sp. and Chaetoceros muelleri and diet C consisted of the same two species, but C. muelleri was grown under silicate deprivation to alter the fatty acid composition. Pediveligers (28 days old) were sampled prior to settlement for fatty acid analysis, growth measurement and survival assessment. Survival and settlement success were measured at the end of the experiment (day 40). Our results show that feeding regime greatly influenced larval size, settlement and fatty acid composition. Diet A was severely deficient in arachidonic acid (20:4n-6, AA), leading to the poorest larval growth, survival and lipid content. Nevertheless, larvae fed diet A selectively accumulate AA by a factor three compared to the dietary amount. Shell size of 28-day-old larvae was positively correlated with AA content and negatively correlated with eicosapentaenoic acid (20:5n-3, EPA)-AA ratio, thus suggesting that these two variables are of major interest for the optimisation of larval growth in sea scallops. Finally, larvae fed diet C displayed 20% higher shell size at day 28 than larvae fed diet A and B, likely in relation to the dietary amount of saturated fatty acid (SFA). However, the moderate survival and settlement success of these groups of larvae might be associated with a relative deficiency in docosahexaenoic acid (22:6n-3, DHA). This study underlines that the overall balance between polyunsaturated fatty acid (PUFA) needs to be considered to adequately fed sea scallop larvae.     

Bone lipids and fatty acids of Peru fish

The neurocranium of the vieja, Pimelometopon darwini, and the cojinoba, Seriolella violacea, contained 29.5 and 26% lipid (as percent dry weight), mostly as triacylglycerol. The anchoveta, Engraulis ringens; sardina, Sardinops sagax sagax; doncella, Halichoeres dispilis; and mackerel, Scomber japonicus, contained less lipid in the neurocranium (3.3–18.4%). Polyunsaturated fatty acids, dominated by 20:5 and 22:6, were highest for S. violacea (10.6–56.1%) and P. darwini (12.2–28.9%). Lower levels of polyunsaturated fatty acids were found in E. ringens. The major monosaturated fatty acids in all Peruvian fish included 16:1n7, 18:1n9 + 11, and 18:n7, whereas the major saturated fatty acids were 14:0 and 16:0 with lesser amounts of 18:0.     

Maintenance of lower proportions of (n − 6) eicosanoid precursors in phospholipids of human plasma in response to added dietary (n − 3) fatty acids

Competition between the (n ? 3) and (n ? 6) types of highly unsaturated fatty acids can diminish the abundance of (n ? 6) eicosanoid precursors in a tissue, which in turn can diminish the intensity of tissue responses that are mediated by (n ? 6) eicosanoids. The mixture of 20- and 22-carbon highly unsaturated fatty acids maintained in the phospholipids of human plasma is related to the dietary intake of 18:2 (n ? 6) and 18:3 (n ?3) by empirical hyperbolic equations in a manner very similar to the relationship reported for laboratory rats (Lands, W.E.M., Morris, A. and Libelt, B. (1990) Lipids 25, 505–516). Analytical results from volunteers ingesting self-selected diets showed an inter-individual variance for the proportion of (n ? 6) eicosanoid precursors in the fatty acids of plasma phospholipids of about 5%, but the variance among multiple samples taken from the same individual throughout the day was less (about 3%), closer to the experimental variance of the analytical procedure (about 1%). The reproducibility of the results makes it likely that analysis of fatty-acid composition of plasma lipids from individuals will prove useful in estimating the diet-related tendency for severe thrombotic, arthritic of other disorders that are mediated by (n ? 6) eicosanoids. Additional constants and terms were included in the equations to account for the effects of 20- and 22-carbon highly unsaturated (n ? 3) fatty acids in the diet. A lower constant for the 20- and 22-carbon (n ? 3) fatty acids compared to that for the 18-carbon (n ? 3) fatty acid in decreasing the ability of dietary 18:2 (n ? 6) to maintain 20:4 (n ? 6) in tissue lipids confirmed the greater competitive effectiveness of the more highly unsaturated n ? 3 fatty acids in the elongation/ desaturation process. Also, a lower constant for direct incorporation of 20-carbon fatty acids of the n ? 6 vs. the n ? 3 type indicated a greater competitive effectiveness of 20:4 (n ? 6) relative to 20:5 (n ? 3) in reesterification after release from tissue lipids. The equations may be used in reverse to estimate the dietary intakes of the (n ? 3) and (n ? 6) fatty acids by using the composition of the fatty acids that had been maintained in plasma lipids.