Effects of temperature and feed composition on essential fatty acid (n-3 and n-6) retention in Atlantic salmon (Salmo salar L.) parr

Retentions of total n-3 and n-6 essential fatty acids (EFAs) were assessed in Atlantic salmon (Salmo salar L.) parr held at 8 °C and 2 °C until they increased in weight from ca. 19 g to 38 g. Feeds contained sandeel oil or a rapeseed:linseed oil blend at 21 and 34% dietary fat. EFA retention efficiencies [(g EFA gained g EFA ingested-1) × 100] were estimated by the 'mass balance method' from measurements of feed intake, changes in biomass for each tank of fish, and fatty acid compositions of the feeds and fish. The n-3 EFA retentions were higher (overall mean 71%) across feed treatments and temperatures than the n-6 EFA retentions (overall mean 63%). Retentions of the n-3 fatty acids were higher in the fish given the feeds with the lower fat content (77% vs. 65%), implying improved retention with reduced n-3 EFA availability. n-3 EFA retention tended to be higher at 2 °C than at 8 °C, although this was not consistent across feeds. At low temperature there was very high retention of the n-3 EFAs in feeds containing sandeel oil (80%). Such high retention may represent an adaptation response to low temperature. Lower n-6 EFA retentions imply that more n-6 fatty acids were metabolized than n-3 EFAs. Feed oil influenced retention of the n-6 fatty acids, retention being lower for the salmon parr given the feeds containing sandeel oil (56% vs. 71%). This could indicate a higher tissue deposition of n-6 fatty acids when they are freely available via the diet. Abbreviations: AA – arachidonic acid (C20:4 n-6); DHA – docosahexaenoic acid (C22:6 n-3); EFA – essential fatty acid; EPA – eicosapentaenoic acid (C20:5 n-3); HUFA – highly-unsaturated fatty acid (\ge4 double bonds); MUFA – monounsaturated fatty acid (1 double bond); PL – phospholipid; PUFA – poly-unsaturated fatty acids (\ge2 double bonds); SFA – saturated fatty acid (no double bond); TAG – triacylglycerol. This revised version was published online in July 2006 with corrections to the Cover Date.     

Influence of nutrition on the lipid quality of pond fish: common carp (Cyprinus carpio) and tench (Tinca tinca)

Like marine fish freshwater fish are an important source of essential fatty acids for human nutrition. However, the fatty acid composition of pond fish can vary considerably and strongly depends on that of the ingested food. Investigations on the fatty acid composition of common carp (Cyprinus carpio) and tench (Tinca tinca) have shown that different methods of rearing and feeding cause substantial variations in the proportions of the n-6 and n-3 polyunsaturated fatty acids of these fish species. Carp reared on the basis of natural food in ponds exhibit high contents of n-6 as well as n-3 fatty acids in their muscle triacylglycerols. On the other hand carp fed supplementary wheat in ponds resulted in somewhat lower levels of these essential fatty acids. High amounts of n-3 fatty acids can be found in carp fed high-energy diets containing high levels of fish oil. Analogous results were obtained in experiments with tench reared under different nutritional conditions. While rearing on the basis of only natural food in ponds as well as feeding supplementary wheat yielded in similar levels of n-3 and n-6 polyunsaturated fatty acids, higher contents of n-3 fatty acids were recorded in tench fed pellets. High levels of n-3 polyunsaturated fatty acids in foodstuffs have positive effects on human health. Experiments with different cultured fish species proved that the fatty acid composition of the edible parts can be influenced by the diet. Therefore, a finishing diet with a suitable fatty acid profile can be used to improve the nutritional quality of fish products of farmed origin.     

Essential fatty acids in Atlantic salmon: time course of changes in fatty acid composition of liver, blood and carcass induced by a diet deficient in n-3 and n-6 fatty acids

Atlantic salmon fry (4 g) were fed a semi-synthetic diet devoid of n-3 and n-6 polyunsaturated fatty acids (PUFA) for 4 months. External signs of nutritional imbalance during the period were slow growth rate and increased mortality. Some symptoms of essential fatty acid deficiency appeared in the fatty acid composition of the blood and liver during the fourth month. At that time, the percentages of n-3 and n-6 PUFA of triacylglycerols (TAG) were nearly exhausted, and the percentages of 22:6 n-3 and of 20:5 n-3 in phospholipids (PL) showed a marked decrease. This decrease in the PUFA level of the PL was paralleled by the appearance of 20:3 n-9, whereas in the TAG an increase in the percentage of 18:1 n-9 was observed. After 4 months the monounsaturated fatty acid 18:1 n-9 constituted nearly 50% of the fatty acids in the TAG fraction of the liver. The time course of the changes in fatty acid composition of liver and blood lipids was quite similar, whereas the carcass lipid composition appeared to respond slowly to a diet devoid of essential fatty acids.     

Dynamics of total lipids and fatty acids during embryogenesis and larval development of Eurasian perch (Perca fluviatilis)

Total lipid and fatty acid compositions were determined during embryogenesis and larval development in Eurasian perch (Perca fluviatilis). During embryonic development, perch did not catabolize lipids and fatty acids as an energy source. However, during larval development, there was an exponential relationship between the decrease in total lipids and the duration of starving (r ²=0.9957) and feeding (r ²=1). The duration of the starving period (10 days post hatching) was shorter than the feeding period (35 days post hatching). In both starved and fed larvae, there is an apparent preference in utilization of polyunsaturated fatty acids followed by monounsaturated fatty acids. Saturated fatty acids were utilized by neither fed perch larvae nor by starved perch larvae. In starved larvae, palmitoleic 16:1(n-7) and oleic 18:1(n-9) acids were the preferentially monounsaturated fatty acids catabolized and their contribution as energy source from total fatty acids catabolized over the first week was 37.6%. In fed larvae, these 2 nutrients were also the most monounsaturated fatty acids utilized as energy source and possibly also as precursors for others monounsaturated fatty acids biosynthesis. During the same period and among (n-6) polyunsaturated fatty acids, starved perch utilized less linoleic 18:2(n-6) and arachidonic 20:4(n-6) acids than fed larvae despite the fact that the starved perch were in more unfavorable nutritional conditions. In the case of (n-3) fatty acids, starved larvae utilized more linolenic acid 18:3(n-3) and less eicosapentaenoic 20:5(n-3) acid and docosahexaenoic 22:6(n-3) acid than fed perch. Starved larvae probably spared 20:5(n-3) and 22:6(n-3) for physiological functions.     

The digestion and selective absorption of dietary fatty acids in Arctic charr, Salvelinus alpinus

To compare the rates of digestion and absorption of individual fatty acids, Arctic charr, Salvelinus alpinus (L.), were fed isoenergetic diets containing 40 g kg^?1 coconut oil, and various combinations of 10 g kg^?1 of polyunsaturated fatty acids (PUFA) (18:2n-6 or 18:3n-3) and monounsaturated fatty acids (MONO) (20:1n-9 or 22:1n-9) in the form of free fatty acids (FFA) or triacylglycerol (TAG). The average lipid digestibility for all diets measured by use of the chromic oxide method in the pyloric caeca area, midgut and hindgut were 72%, 83% and 88%, respectively, showing that lipid digestion and absorption occur mainly in the pyloric caeca area, but also extend throughout the intestinal tract. Analyses of digesta present in the intestinal segments suggest the predominance of non-specific lipolytic activity producing primarily FFA and glycerol from dietary TAG. Comparisons of the fatty acid composition of the lipid classes in the digesta showed that the utilization of dietary TAG was dependent both on the rate of release of the individual fatty acids from TAG, and their subsequent rate of absorption. When supplied as either FFA or TAG, the levels of PUFA (18:2n-6 or 18:3n-3) in the digesta were very low, indicating almost complete utilization. Both MONO used (20:1n-9 or 22:1n-9) were absorbed less efficiently than PUFA, but the rate of release from TAG seemed to be rate limiting only for 22:1n-9, which accumulated in the digesta. The rates of absorption of 20:1n-9 and 22:1n-9 when fed as FFA were the same. Comparisons of the levels of fatty acids in the dietary coconut oil TAG with those of the digesta lipids showed that 12:0 was a good substrate for intestinal lipase and was quickly absorbed. The lipolysis of 14:0 and 16:0 was intermediate while the longer-chain 18:0 appeared very resistant to digestion and was a major component of TAG, diacylglycerols and monoacylglycerols present in particularly the hindgut digesta. The absorption of 18:0 also appeared to be very low. The results suggest that PUFA are released very rapidly from dietary TAG by intestinal lipases in Arctic charr, and are specifically absorbed compared with long-chain saturated and monounsaturated fatty acids. The rate of lipolysis may be the rate-limiting step in the digestion of very long chain monounsaturated fatty acids such as 22:1n-9, while both the rate of lipolysis and absorption may be rate limiting for long-chain saturated fatty acids such as 18:0.     

Importance of fatty acids in broodstock diets with emphasis on Arctic char (Salvelinus alpinus) eggs

The importance of long-chain polyunsaturated fatty acids, especially the eicosanoid precursors, is addressed in this paper. It has been generally recognized that eicosapentaenoic (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3) are of significant importance in fish reproduction while arachidonic acid (AA, 20:4n-6) has often been overlooked. The ratio between C20 fatty acids EPA and AA might be important for many physiological functions depending on the species evolution and its requirements. Arctic char (Salvelinus alpinus) has a much more pronounced freshwater history and therefore different fatty acid requirements than the other commonly farmed salmonids such as salmon (Salmo salar), brown trout (Salmo trutta) and rainbow trout (Oncorhynchus mykiss). Therefore there is reason to formulate a feed that is more suitable for farming of this freshwater species. In this study, freshwater wild-origin char eggs were compared to farmed eggs of char. The ratio n-3/n-6 of total phospholipids of eggs was much lower in the wild fish, 3.5 versus 13.5, and the hatching rate of eggs from natural environment was much higher (20–70% vs. >80%). We conclude that feed based on marine raw product does not fulfill the requirements for essential fatty acids for freshwater char and we suggest that AA is supplemented to the broodstock diet and that at least linoleic acid (18:2n-6) is included in the on-growth diet formulas to lower the n-3/n-6 fatty acid ratio.     

Essential fatty acid requirement of juvenile red drum (Sciaenops ocellatus)

Feeding experiments and laboratory analyses were conducted to establish the essential fatty acid (EFA) requirement of red drum (Sciaenops ocellatus). Juvenile red drum were maintained in aquaria containing brackish water (5 ± 2‰ total dissolved solids) for two 6-week experiments. Semipurified diets contained a total of 70% lipid consisting of different combinations of tristearin [predominantly 18:0] and the following fatty acid ethyl esters: oleate, linoleate, linolenate, and a mixture of highly unsaturated fatty acids (HUFA) containing approximately 60% eicosapentaenoate plus docosahexaenoate. EFA-deficient diets (containing only tristearin or oleate) rapidly reduced fish growth and feed efficiency, and increased mortality. Fin erosion and a “shock syndrome” also occurred in association with EFA deficiency. Of the diets containing fatty acid ethyl esters, those with 0.5–1% (n-3) HUFA (0.3–0.6% eicosapentaenoate plus docosahexaenoate) promoted the best growth, survival, and feed efficiency; however, the control diet containing 7% menhaden fish oil provided the best performance. Excess (n-3) HUFA suppressed fish weight gain; suppression became evident at 1.5% (n-3) HUFA, and was pronounced at 2.5%. Fatty acid compositions of whole-body, muscle and liver tissues from red drum fed the various diets generally reflected dietary fatty acids, but modifications of these patterns also were evident. Levels of saturated fatty acids appeared to be regulated independent of diet. In fish fed EFA-deficient diets (containing only tristearin or oleate), monoenes increased and (n-3) HUFA were preferentially conserved in polar lipid fractions. Eicosatrienoic acid [20:3(n-9)] was not elevated in EFA-deficient red drum, apparently due to their limited ability to transform fatty acids. Red drum exhibited some limited ability to elongate and desaturate linoleic acid [18:2(n-6)] and linolenic acid [18:3(n-3)]; however, metabolism of 18:3(n-3) did not generally result in increased tissue levels of (n-3) HUFA. Based on these responses, the red drum required approximately 0.5% (n-3) HUFA in the diet (approximately 7% of dietary lipid) for proper growth and health.     

黄颡鱼早期发育阶段受精卵和鱼体脂肪酸组成变化

研究了黄颡鱼受精卵孵化期间和仔鱼发育阶段脂肪含量和脂肪酸的组成变化规律.采用常规化学分析方法和气相色谱法对黄颡鱼从鱼卵受精开始至仔鱼孵化后未投饵的7 d内的脂肪含量和脂肪酸组成进行测定.结果表明,受精卵在整个孵化期间脂肪含量有下降趋势.受精卵中不饱和脂肪酸含量大于饱和脂肪酸含量.受精卵在整个孵化期间各种脂肪酸含量无明显变化.仔鱼孵化后,鱼体总脂肪含量急剧下降,总脂含量从0日龄的4.57%降低到7日龄的0.75%.仔鱼在饥饿期间鱼体脂肪酸组成发生明显变化,单不饱和脂肪酸含量下降最为明显,尤其是C18:1.仔鱼在饥饿期间,脂肪酸按n-9>n-6>n-3顺序被先后利用,黄颡鱼仔鱼发育阶段主要以单不饱和脂肪酸作为能量代谢基质,而C20:4n6(AA)和C22:6n3(DHA)优先于C20:5n3(EPA)被保存下来.     

Effects of salinity on the fatty acid compositions of total lipid and individual glycerophospholipid classes of Atlantic salmon (Salmo salar) and turbot (Scophthalmus maximus) cells in culture

Cells from a relatively stenohaline marine species, turbot (Scophthalmus maximus) (TF) and an anadromous species, Atlantic salmon (AS) were cultured in media supplemented with NaCl to produce OPs varying from 300 to 500 mOsm kg^–1 and the direct effects of OP (salinity) on the fatty acid compositions of the main glycerophospholipid classes were determined. The most dramatic effects of salinity on total lipid fatty acids were observed in polyunsaturated fatty acids (PUFA) in TF cells. There was a graded decrease in the percentage of 18:2n-9, and consequently total n-9 PUFA, and concomitantly increased percentages of both total n-3 and n-6 PUFA with increasing salinity. The increased n-3 and n-6 PUFA was due to significantly increased percentages of the major fatty acids in each of these groups, namely 22:6n-3 and 20:4n-6, respectively. The reciprocal changes in n-9 PUFA and n-3/n-6 PUFA in TF cell total lipid resulted in the percentage of total PUFA not being significantly affected by changes in salinity. The graded decrease in 18:2n-9 with increasing salinity in TF cells was observed in all the major glycerophospholipids but especially PE, PI and PS. Increasing salinity resulted in graded increases in the percentages of 22:6n-3 in PE and PS in TF cells. The quantitatively greatest increase in the percentage of n-6 PUFA in TF cells occurred with 20:4n-6 in PC, PE and PL. There were less significant changes in the fatty acid compositions of glycerophospholipids in AS cells. However, the proportion of total n-3 + n-6 PUFA in PE varied reciprocally with the proportion of dimethylacetals in response to salinity. Similar reciprocal changes between fatty acids in response to salinity were also evident in the quantitatively more minor glycerophospholipids PS and Pl. In PS, the percentage of 22:6n-3 was significantly lower at 400 mOsm kg^–1 whereas the proportion of total monoenes was significantly higher at that salinity. A similar inverse relationship between total monoenes and 20:4n-6 (and, to a lesser extent total saturates) in response to salinity was noted in PI. The results show that environmental salinity, without whole-body physiological stimuli, has direct effects on the fatty acid composition of major glycerophospholipid classes in fish cells and that these effects differ in cells from different fish speciesAbbreviations ANOVA analysis of variance - BHT butylated hydroxytoluene - BSA bovine serum albumin - DMA dimethylacetals - EMEM Eagle's minimal essential medium - FCS fetal calf serum - GC gas chromatography - HBSS Hank's balanced salt solution (without Ca²⁺ and Mg²⁺) - OP osmotic pressure - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PS phosphatidylserine - PUFA polyunsaturated fatty acid - TLC thin-layer chromatography     

Lipid characteristics of coastal migratory Sarda orientalis tissues

To characterize the 22:6 n-3 (docosahexaenoic acid, DHA) levels of the oriental bonito Sarda orientalis, a coastal migratory tuna species, total lipids (TL) of white muscle, dark muscle, liver, pyloric cecum, gonad, and other viscera were separated into lipid classes, the constituents of TL were quantified, and the fatty acid composition of TL, triacylglycerols (TAG), phosphatidylethanolamine, and phosphatidylcholine was analyzed. The crude lipid contents of muscle and other organs were 0.8–3.2% and 2.3–9.1%, respectively. DHA was found in TL of various organs at levels ranging from 19.2% to 27.6% in muscle and 16.3% to 28.5% in other organs. The levels of DHA in muscle TAG (8.2–16.0%) were lower than or comparable to those in visceral TAG (6.9–24.0%). These findings did not coincide with those observed in active-migratory tuna species, which accumulate DHA in their muscle TAG during migration. These findings suggest that the DHA distribution of S. orientalis is different from that observed in active-migratory tuna species, and that the differences may be due to migration type of the fish.     

Relationship between dietary lipid source, oxidative stress, and the physiological response to stress in sub-yearling chinook salmon (Oncorhynchus tshawytscha)

Relationships between dietary lipid source, stress, and oxidative stress were examined in juvenile chinook salmon (Oncorhynchus tshawytscha). Four different experimental diets were used: menhaden oil (MHO; elevated 20:5n-3 and 22:6n-3), soybean oil (SBO; elevated 18:2n-6), linseed oil (LSO; elevated 18:3n-3), and a mixture of 55% linseed oil and 45% soybean oil (MIX; approximately equal levels of 18:2n-6 and 18:3n-3). Juvenile salmon (initial body weight of 16.0 g) were fed experimental diets for 12 weeks (early March to early June). At the end of feeding, fish subjected to a low-water stressor for 96 h had greater liver and brain lipid peroxidation compared to unstressed controls; peroxidation was not influenced by diet. Diet and stress affected plasma cortisol levels. Stressed fish fed SBO had the greatest cortisol concentrations, followed by MIX, MHO, and LSO (mean concentrations for the SBO and LSO diets differed significantly). The cortisol response to stress may have been influenced by the ratio of prostaglandin 1- and 2-series to prostaglandin 3-series precursor fatty acids provided by the different diets. The results of this study suggest a connection between the physiological response to stress, dietary lipid quality, and oxidative stress. This is the first evidence of such a relationship in fish. Abbreviations: AA - arachidonic acid; ACTH - adrenocorticotropin; BHT - butylated hydroxytoluene; BLPO - brain lipid peroxidation; dGLA - dihomo-γ-linolenic acid; DHA - docosahexanoic acid; EPA - eicosapentanoic acid; FER - feed efficiency ratio; FOX - ferrous oxidation-xylenol orange; GLA -γ-linolenic acid; LA - linoleic acid; LCO3 - long-chain n-3 polyunsaturated fatty acids; LLPO - liver lipid peroxidation; LN - linolenic acid; LPO - lipid peroxidation; LSO - linseed oil; MHO - menhaden oil; MIX - 55% linseed oil + 45% soybean oil; PC - plasma cortisol; PG - prostaglandin(s); PGE₂- prostaglandin E₂; PUFA - polyunsaturated fatty acid; SBO - soybean oil. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effect of soybean oil and soybean lecithin on intestinal lipid composition and lipid droplet accumulation of rainbow trout, Oncorhynchus mykiss Walbaum

Rainbow trout (Oncorhynchus mykiss Walbaum) were fed purified diets containing fish oil for six weeks and then soybean lecithin or soybean oil for 25 days. The gastrointestinal tract segments, stomach, midgut and hindgut were then sampled for lipid and fatty acid composition and electron microscopy. Membrane lipid class composition was fairly similar in all three segments of trout fed fish oil. Hindgut contained slightly more phosphatidylserine than stomach and midgut, while midgut contained more phosphatidylcholine and less lysophospatidylcholine/sphingomyelin. Feeding soybean products appeared to marginally decrease free cholesterol. The fatty acid compositions of the main lipid classes showed significant regional differences. In control fish, stomach had higher levels of arachidonic acid (20:4n-6) and n-6 polyunsaturated fatty acids than midgut and hindgut, and lower content of docosahexaenoic acid (22:6n-3) and n-3 polyunsaturated fatty acids. Midgut phosphatidylethanolamine also had higher levels of saturated fatty acids and less n-3 polyunsaturated fatty acids than the other tissues. Feeding soybean products decreased the n-3/n-6 ratio mainly due to increases in linoleic (18:2n-6) and 20:4n-6 and decreases in 22:6n-3 and eicosapentaenoic acid (20:5n-3). Phosphatidylcholine and to a lesser extent phosphatidylethanolamine adapted more readily to dietary changes by major increases in 18:2n-6 and C₂₀₋₂₂ n-6 polyunsaturated fatty acids. The composition of phosphatidyl-serine and -inositol appeared to be under more strict metabolic control. Linoleic acid hardly increased at all while the increase in other n-6 polyunsaturated fatty acids was less pronounced than for the other lipid classes. Regardless of lipid class, stomach resisted dietary changes more strongly than midgut and hindgut. Increases in n-6 polyunsaturated fatty acids were minor as were the loss of n-3 polyunsaturated fatty acids. The dead-end product 20:2n-6 accumulated to a higher degree in hindgut phosphatidyl-ethanolamine and -coline compared to midgut and stomach, suggesting that the activity of Δ₆ desaturation is higher in the anterior part of the intestine where most of the lipid is absorbed. Feeding soybean oil caused massive accumulation of free lipid droplets in midgut enterocytes while little lipid droplets were observed in trout fed fish oil or soybean lecithin. Since both soybean products influenced intestinal composition to the same degree, altered fatty acid profiles in membranes is not responsible for the observed lipid accumulation. This supports previous observations in Arctic charr (Salvelinus alpinus L.), suggesting that fish may require exogenous phospholipids in order to sustain a sufficient rate of lipoprotein synthesis. This revised version was published online in July 2006 with corrections to the Cover Date.     

Variation in the Fatty Acid Composition Between and Within Two Mantis Shrimp Species,Harpiosquilla harpax and Miyakea nepa: Impact of Season and Sex

ABSTRACT

Harpiosquilla harpax and Miyakea nepa are two out of 400 marine crustaceans commonly known as mantis shrimp. Mantis shrimp are commercially valuable and can be found in fish markets of some Mediterranean and many Asian countries. This study focused on a comparative analysis of variation throughout the year in regards to proximate and total fatty acid composition in the muscle of male and female H. harpax and M. nepa. The most abundant fatty acids identified in the muscle of both species were C16:0, C18:0, docosahexaenoic acid (DHA; C22:6n-3), eicosapentaenoic acid (EPA; C20:5n-3), and C20:4n-6. Results of this study revealed that the muscle fatty acid profiles of H. harpax and M. nepa were not significantly different (p > 0.05), except for C14:0, C16:0, C22:0, and DHA amounts, and were mostly influenced by sex within each sampling month. Generally, the muscle of H. harpax contained higher (p < 0.05) levels of DHA than the muscle of M. nepa. The male mantis shrimp, within each species and most of the sampling months, appeared to have higher (p < 0.05) DHA, total n-3 polyunsaturated fatty acid (PUFA), and PUFA/saturated fatty acid ratio compared to the females. Both species could be considered as a good source of n-3 PUFA in the human diet.     

二种海胆性腺的脂质组成及其抗氧化活性

为分析马粪海胆和光棘球海胆性腺的脂质组成和抗氧化活性，采用核磁共振和气相色谱—质谱技术对2种海胆性腺油脂的脂质成分和脂肪酸组成进行分析，并通过DPPH自由基清除法、羟基自由基清除法和超氧阴离子自由基清除法对其脂质的抗氧化活性进行研究。结果显示，马粪海胆和光棘球海胆性腺脂质均以甘油三酯和磷脂为主，胆固醇、胆固醇酯和游离脂肪酸含量较低。马粪海胆和光棘球海胆性腺总脂富含C20:4n-6和C20:5n-3，且二者总量分别占脂肪酸含量的35.88%和34.98%；同时2种海胆性腺的中性脂和极性脂的脂肪酸组成存在较大差异，中性脂以C14:0和C16:0等饱和脂肪酸为主，而极性脂以C20:4n-6和C20:5n-3等多不饱和脂肪酸为主。马粪海胆和光棘球海胆性腺脂质对DPPH自由基、羟基自由基和超氧阴离子自由基均具有较好的清除能力，DPPH自由基IC₅₀分别为2.75和1.98 mg/mL，羟基自由基IC₅₀分别为0.33和0.29 mg/mL，超氧阴离子自由基IC₅₀分别为0.33和0.31 mg/mL。研究表明，马粪海胆和光棘球海胆性腺脂质具有较高的营养价值和抗氧化活性，可作为C20:4n-6、C20:5n-3和磷脂等功能性脂质因子的重要膳食来源。     

Dynamics of Total Body Fatty Acids During Early Ontogeny of Pikeperch (<Emphasis Type="Italic">Sander lucioperca</Emphasis>) Larvae

The fatty acid composition of pikeperch (Sander lucioperca) was determined according to their physiological status, during starvation (10 days) and feeding (28 days). In starved larvae, polyunsaturated, monounsaturated and saturated fatty acids were utilized as metabolic substrates until day 9. At day 10, all fatty acid levels remained stable or, at least, increased in larval body. Among fatty acids, docosahexaenoic acid 22:6 n-3 was used preferentially (20.3% from total fatty acids utilized) followed by palmitoleic acid 16:1 n-7 (13.9%) and then by oleic 18:1 n-9 (12.3%), linoleic 18:2 n-6 (10.1%), linolenic 18:3 n-3 (9.7%) and eicosapentaenoic 20:5 n-3 (9.1%) acids. On the other hand, arachidonic acid 20:4 n-6 was utilized very lowly (0.3%). In fed larvae, no utilization of body fatty acids was observed during the experiment. It seems that energy requirements (and others) of fed larvae were satisfied by feed.     

Fatty Acid Profiles and Lipid Oxidation Status of Sun Dried,Deep Fried,and Smoked Sardine (Rastrineobola argentea) from Lake Victoria,Tanzania

Freshwater fishes contain long chain omega-3 and omega-6 polyunsaturated fatty acids (PUFAs) of highest nutritional value. PUFAs in fish are susceptible to oxidative damage during processing and subsequent storage. Sardines (Rastrineobola argentea) are an important fish species of Lake Victoria, constituting 72.3% of the total landings by weight on the Tanzanian side of the lake. Fatty acid profiles and lipid oxidation status of sun-dried, deep-fried, and smoked sardines were investigated. Lipid oxidation was assessed by peroxide value, thiobarbituric acid reactive substances (TBARS), and free fatty acids. Fatty acids were analyzed by gas chromatography with flame ionization detector. The three omega-3 PUFAs: docosahexaenoic acid (C22:6n-3), docosapentaenoic acid (C22:5n-3), and eicosapentaenoic acid (C20: 5n-3) contributed 57–60, 63, and 38% of PUFAs in sun-dried, smoked, and deep-fried sardines, respectively. Lipid oxidation reactions were more pronounced in sardines dried on sand and rocks, with TBARS values 97.87 and 84.18 µmolMDA/kg, respectively. The polyene index was significantly lower (p < 0.05) in deep-fried sardines, indicating lower retention of PUFAs in the product. Lake Victoria sardines are a rich source of omega-3 PUFAs. PUFAs in sun-dried sardines are prone to oxidative damage. Smoking resulted in relatively higher retention of omega-3 fatty acids in products.     

Occurrence of all-<Emphasis Type="Italic">cis</Emphasis>-5,8,11,14,17,20,23-hexacosaheptaenoic acid (26:7n-3) in roughscale sole <Emphasis Type="Italic">Clidoderma asperrimum</Emphasis> flesh lipids

Fatty acid analysis of roughscale sole Clidoderma asperrimum flesh lipids was carried out by gas chromatography. An unidentified peak appeared in the chromatogram in the elution region of ≥C24 fatty acids. After enrichment by solvent partitioning, reversed-phase thin-layer chromatography (TLC), and argentation TLC, the peak component was subjected to structural analyses. The partially hydrogenated products after reaction with hydrazine hydrate gave seven isomers of cis-hexacosenoic acid (26:1). Gas chromatography-mass spectrometry (GC–MS) analyses of their dimethyl disulfide adducts identified the monounsaturates as 5-, 8-, 11-, 14-, 17-, 20-, and 23-26:1. The peak component was assigned to all-cis-5,8,11,14,17,20,23-hexacosaheptaenoic acid (26:7n-3). GC–MS analyses of the 4,4-dimethyloxazoline derivative and methyl ester confirmed this structure. This fatty acid is a rare, very long-chain polyunsaturated fatty acid (VLCPUFA). The concentrations of the acid found in roughscale sole were 0.69 ± 0.34% (N = 5) of total fatty acids in flesh lipids. Roughscale sole appears to be characterized by the occurrence of 26:7n-3, which is lacking in popular sources of methylene-interrupted VLCPUFA, such as vertebrate retina, spermatozoa, and herring.     

Can Different Body Tissues of Two Sea Cucumbers Supply a Fair Amount of Omega 3 for Health Benefit?

The lipid content and fatty acids profile of different tissues of Holothuria tubulosa and H. polii were analyzed to assess the suitability of the central Mediterranean species as a potential marine resource for fatty acids, in particular omega-3 polyunsaturated fatty acids (n-3 PUFAs). Simultaneously, their important indices for human health were evaluated. Gonad and respiratory tree had the highest lipid content, while the body had the lowest values. The results showed significant differences between species and among the different portions analyzed. Internal tunic and longitudinal muscle of H. tubulosa exhibited the highest PUFA proportion (55.3 and 46.4%, respectively). Eicosapentaenoic acid (EPA, C20:5n-3) and arachidonic acid (ARA, C20:4n-6) were the most abundant PUFAs in both species, with a favorable n-3/n-6 ratio in all tissues. The atherogenic and thrombogenicity indices and hypocholesterolaemic/hypercholesterolaemic fatty acid ratio suggested the high-quality of this food, similar to the nutritional values of most popular fish.     

The fatty acid composition of Nereis diversicolor cultured in an integrated recirculated system: Possible implications for aquaculture

The potential of solid waste originating from a recirculated fish culture system, i.e. faecal material, uneaten food pellets and bacterial biofilms was examined as food source for the marine polychaete Nereis diversicolor. These polychaetes could be a valuable food for fish if they provide essential fatty acids to the fish. Therefore, we analysed the fatty acid profiles from feed and faecal materials, the sediment as well as the cultured organisms — fish and several batches of N. diversicolor — from an integrated recirculating aquaculture system.The major fatty acids (saturated, monounsaturated and polyunsaturated) for all analysed fish feed, fish and faeces samples were C16:0, C18:1 and C22:6 (n − 3), accounting for 48% to 57% of the fatty acids in the samples. The major fatty acids within the sediment were C16:0, C18:1 and C18:3 (n − 3), accounting for 61% of the total fatty acids. The samples of N. diversicolor revealed C16:0, C18:1 and C20:5 (n − 3) as the major fatty acids. Combined, they accounted for 56% of the total fatty acids detected within the worm samples.The results indicate that a recycling or even an upgrade of excreted feed nutrients such as fatty acids, which were otherwise discharged, can be achieved through integrated aquaculture combining fish and worm culture.     

Nutritional Quality and Safety of the Important Commercial Cuttlefish Sepia lycidas

Proximate composition, amino acid, fatty acid composition, and contaminants (As, Cd, Hg, and Pb) of the kisslip cuttlefish Sepia lycidas were determined and compared with the recommendations and maximum allowed levels. The ratio of essential amino acids (EAA) to nonessential amino acids (NEAA) was 0.82. All of the amino acid scores were > 100, except for valine (93), and the highest essential amino acid score was obtained for tryptophan (327). The fatty acids profile was dominated by polyunsaturated fatty acids (PUFA; 45.01% of total fatty acids), and docosahexaenoic acid (DHA; 24.54% of total fatty acids) was the dominant fatty acid. S. lycidas was rich in n-3 PUFA, and the ratio of n-3/n-6 PUFA was 2.48. Regarding contaminants, As, Cd, and Pb concentrations in S. lycidas were 2.2, 0.28, and 0.02 mg kg^?1, respectively. Moreover, Hg values were below the detection limit (0.01 mg kg^?1).