Lipid and fatty acid composition, and persistent organic pollutant levels in tissues of migrating Atlantic bluefin tuna (Thunnus thynnus, L.) broodstock.

Lipid class, fatty acid and POP levels were measured in migrating Atlantic bluefin tuna (ABT) tissues caught off the Barbate coast, Spain. Tissue lipids were largely characterized by triacylglycerol, reflecting large energy reserves accumulated prior to reproductive migration. Fatty acid compositions of muscle, liver and adipose exhibited similar profiles, whereas gonads showed a higher affinity for docosahexaenoic acid. Tissue POP concentrations correlated positively with percentage triacylglycerol and negatively with polar lipids. Highest POP concentrations were in adipose and lowest in gonads, reflecting lipid content. DL-PCBs contributed most to total PCDD/F + DL-PCB levels, with mono-ortho concentrations higher in tissues, whereas non-ortho PCBs contributed greater WHO-TEQs due to differences in TEFs. PBDE47 was the most prominent BDE congener in tissues, probably through biotransformation of BDE99 and other higher brominated congeners. The perceived POP risk from ABT consumption should be balanced by the well-established beneficial effects on human health of omega-3 fatty acids.

Partial replacement of dietary fish oil with blends of vegetable oils (rapeseed, linseed and palm oils) in diets for European sea bass (Dicentrarchus labrax L.) over a long term growth study: effects on muscle and liver fatty acid composition and effectiveness of a fish oil finishing diet.

Triplicate groups of European sea bass (Dicentrarchus labrax L.), of initial mass 5 g, were fed one of three practical type diets for 64 weeks. The three diets differed only in the added oil and were 100% fish oil (FO; diet A), 40% FO/60% vegetable oil blend (VO; diet B) where the VO blend was rapeseed oil, linseed oil and palm oil in the ratio 10/35/15 by weight and 40% FO/60% VO blend (diet C) where the ratio was 24/24/12 by weight. After final sample collection the remaining fish were switched to a 100% FO finishing diet for a further 20 weeks. After 64 weeks fish fed 60% VO diet B had significantly lower live mass and liver mass than fish fed diets A and C although SGR, FCR and length were not different between groups. There were no differences in any of the above parameters after either 14 or 20 weeks on the FO finishing diet. Fatty acid compositions of flesh were correlated to dietary fatty acids although there was selective retention of docosahexaenoic acid (22:6n-3; DHA) regardless of dietary input. Inclusion of dietary VO resulted in significantly reduced flesh levels of DHA and eicosapentaenoic acid (20:5n-3; EPA) while 18:1n-9, 18:2n-6 and 18:3n-3 were all significantly increased in fish fed the 60% VO diets. Fatty acid compositions of liver showed broadly similar changes, as a result of dietary fatty acid composition, as was seen in flesh. However, the response of flesh and liver to feeding a FO finishing diet was different. In flesh, DHA and EPA values were not restored after 14 or 20 weeks of feeding a FO finishing diet with the values in fish fed the two 60% VO diets being around 70% of the values seen in fish fed FO throughout. Conversely, and despite liver DHA and EPA levels being reduced to only 40% of the value seen in fish fed 100% FO after 64 weeks, the levels of liver DHA and EPA were not significantly different between treatments after feeding the FO finishing diet for 14 weeks. However, a 200 g portion of sea bass flesh, after feeding the experimental diets for 64 weeks followed by a FO diet for 14 weeks, contained 1.22 and 0.95 g of EPA+DHA for fish fed FO or 60% VO, respectively. Therefore, sea bass grown for most of the production cycle using diets containing 60% VO can still contribute a significant quantity of healthy n-3 HUFA to the human consumer.

Changes in the content of total lipid, lipid classes and their fatty acids of developing eggs and unfed larvae of the Senegal sole,Solea senegalensis Kaup.

Total lipids, lipid classes and their associated fatty acids were quantified in developing eggs, yolk-sac larvae and starving larvae (from day 1 to day 5 after hatching) of the Senegal sole,Solea senegalensis Kaup. Larvae during early development and starvation consumed about 0.6% of its dry weight per day, mainly due to lipid catabolism. There was a net consumption of approximately 1.7% total lipid per day, and a net energy utilization of 1.3 kcal g(-1) dry weight biomass day(-1), mostly derived from lipid depletion. The overall decrease of total neutral lipids (mainly triacylglycerols and sterol esters) was 3.4 faster than that of total polar lipids (primarily phosphatidylcholine), with rates of 29.2 and 8.7 µg mg(-1) dry weight biomass day(-1), respectively. There was a concomitant increase in PE, PS and phosphatidic acid during the period under study. Total saturated and total monounsaturated fatty acids were catabolized (primarily 16∶0 and 16∶1 (n-7)) as energy substrates at rates of 7.4 and 10.9 µg mg(-1) total lipid day(-1), whereas total PUFAs were conserved. DHA was specifically retained in PE, whereas EPA and DHA were catabolized in PC and triacylglycerol. Total DMA and AA contents in total lipid increased during early development and starvation. The data denote a pattern of lipid metabolism during early development of Senegal sole similar to that of other marine larval fish, with eggs containing high amounts of total lipids (presence of oil globule/s), from temperate waters and with short developmental periods; the pattern contrasts with fish larvae from eggs of cold water fish species that contain low levels of total lipids (lack of oil globule/s) and have long developmental periods.

[Effects of pharmacological doses of polyunsaturated fatty acids of the series 3 on the concentration of plasma lipoproteins]. / Influencia de las dosis farmacológicas de ácidos grasos poliinsaturados de la serie-3 sobre la concentración de lipoproteínas plasmáticas.

Cardiovascular disease is one of the main causes of death in developed countries. Its incidence may be modified through dietary changes, this being supported by the low incidence of the disease among populations with high intake of fatty fishes. The aim of this work was to study the modifications on plasmatic levels of polyunsaturated fatty acids omega 3 after an additional supply of fish oils and to assess its effect on the metabolism of lipids and lipoproteins. The study was conducted on 8 healthy volunteers, their age ranging between 24 and 37 years. They received, during 30 days and in tablets of 500 mg, 7.5 gr/24 h of fish oil concentrate which supplied 2.5 gr/24 h of fatty acids omega 3. After 12 hours of fasting, blood samples were taken before and after the intake of this concentrate. Methyl esters from fatty acids omega 3 were assessed through gas chromatography; cholesterol, triglycerides, LDL, VLDL, HDLt, HDL2 and HDL3, through several enzymatic techniques; and lipoprotein(a) Lp(a), through ELISA. The statistical analysis was conducted using the Student's method for matched data. After 30 days of supplement, we observed: a significant increase in the plasmatic percentage of fatty acids omega 3 (EPA + DHA) along with a significant decrease of triglycerides, VLDL and HDL3 and a significant increase of HDL2, We did not observe any significant changes in cholesterol, LDL and HDLt. With respect to Lp(a), after one month of dietary supplement, its plasmatic levels did not change. Our results supports the clinical usefulness of the dietary supplementation with fatty acid omega 3 for the management of hypertriglyceridemias.(ABSTRACT TRUNCATED AT 250 WORDS)

In vivo metabolism of [1-14C]linolenic acid (18:3(n-3)) and [1-14C]eicosapentaenoic acid (20:5(n-3)) in a marine fish: time-course of the desaturation/elongation pathway.

The metabolism (via the desaturation/elongation pathways) of [1-14C]18:3(n-3) and [1-14C]20:5(n-3) in a marine fish, gilthead sea bream (Sparus aurata L.), were investigated over 8 days to determine the time-courses for the production of delta 6 and delta 5-desaturase products and 22:6(n-3). Fish were starved for 1 week prior to, and during, the period of the experiment. The recovery of radioactivity from [1-14C]20:5(n-3) in tissue lipids exceeded that of [1-14C]18:3(n-3) at all time points. The recoveries of both fatty acids decreased by 85-89% between days 2 and 8, indicating that substantial loss of radioactivity due to beta-oxidation occurred. Incorporation of 18:3(n-3) and 20:5(n-3) was predominantly into triacylglycerol but during the time-course of the experiment there were decreased percentages of radioactivity from both labelled fatty acids recovered in triacylglycerol with concomitant increased percentages recovered in phospholipids indicating preferential oxidation of fatty acids in triacylglycerol and/or redistribution of incorporated fatty acids. Recovery of radioactivity in 22:6(n-3) was 10-fold greater with [1-14C]20:5(n-3) than with [1-14C]18:3(n-3). However, there were few consistently significant trends in the levels of components of the desaturation/elongation pathways during the time-course of the experiment. In particular, the relative recovery of radioactivity in 22:6(n-3) did not increase during the experiment with either substrate. Substantial amounts of radioactivity were found in 24:5(n-3) and 24:6(n-3), particularly after injection with [1-14C]20:5(n-3), indicating that the conversion of 20:5(n-3) to 22:6(n-3) in sea bream may occur by a pathway utilizing delta 6-desaturase activity rather than by a delta 4-desaturation.

Incorporation and metabolism of(14)C-labelled polyunsaturated fatty acids in wild-caught juveniles of golden grey mullet,Liza aurata, in vivo.

The incorporation, and the capacity for desaturation and elongation in vivo, of intraperitoneally-injected,(14)C-labelled n-3 and n-6 C18 and C20 polyunsaturated fatty acids (PUFA) were investigated in juvenile golden grey mullet,Liza aurata. The results indicate that juvenile mullet have only limited ability to convert C18 polyunsaturated fatty acids to C20 and C22 highly unsaturated fatty acids (HUFA)in vivo. This suggests that juvenile golden grey mullet require the provision of preformed C20/22 HUFA, such as eicosapentaenoic and docosahexaenoic acids, in the diet. The impairment in the desaturase/elongase pathway was similar to that found in turbot,Scophthalmus maximus, and gilthead sea bream,Sparus aurata, being primarily at the level of Δ5-desaturase. The data from the largely herbivorous golden grey mullet juveniles are consistent with the hypothesis that marine fish in general, irrespective of dietary habits, have limited capacity for the desaturation and elongation of C18 PUFA. The defect in Δ5-desaturase activity combined with the consistent finding that arachidonic acid is selectively incorporated and retained in membrane phosphatidylinositol suggests that, like turbot and gilthead sea bream, golden grey mullet may also have a requirement for preformed arachidonic acid in the diet.

Incorporation and metabolism of (14)C-labelled polyunsaturated fatty acids in juvenile gilthead sea bream Sparus aurata L. in vivo.

The incorporation, and the capacity for desaturation and elongation in vivo, of intraperitoneally-injected, (14)C-labelled n-3 and n-6 C18 and C20 PUFAs were investigated in juvenile gilthead sea bream, Sparus aurata. The results indicate that juvenile gilthead sea bream have only limited ability to convert CH PUFAs to C20 and C22 HUFAs in vivo. The data are consistent with the results from nutritional studies on larvae, postlarvae and fingerlings that have shown that gilthead sea bream require the provision of preformed eicosapentaenoic and docosahexaenoic acids in the diet. The impairment in the desaturase/elongase pathway was quantitatively and qualitatively similar to that found in turbot, Scophthalmus maximus, being at the level of the Δ5-desaturase. The low activity of Δ5-desaturase combined with the consistent finding that arachidonic acid is selectively retained in membrane phosphatidylinositol suggests that, in addition to eicosapentaenoic and docosahexaenoic acids, gilthead sea bream may also have a requirement for preformed arachidonic acid in the diet.

Effect of broodstock diets on lipid classes and their fatty acid composition in eggs of gilthead sea bream (Sparus aurata L.).

Total lipid content, total lipid fatty acids, lipid classes and their fatty acid compositions were studied in eggs of gilthead sea bream from two different broodstocks.The two broodstock diets used had the same total lipid content, but differed with respect to their fatty acid levels. The lipid class composition of eggs from different origins was not significantly different. The predominant polar lipids were phosphatidylcholine, phosphatidylethanolamine and sphingomyelin, and the main neutral lipid classes were cholesterol esters and triacylglycerols.The fatty acid composition of total lipids and main lipid classes in the two groups of eggs showed marked differences, reflecting the influence of fatty acid levels in the broodstock diets.

Effect of broodstock diets on total lipids and fatty acid composition of larvae of gilthead sea bream (Sparus aurata L.) during yolksac stage.

Total lipid content and total lipid fatty acid compositions were studied in larvae at the yolksac stage of gilthead sea bream from two different broodstocks. The two broodstock diets had the same total lipid content but were different with respect to their fatty acid levels.There were differences in the fatty acid composition of total lipids in the two groups of larvae, reflecting the influence of fatty acid levels in the diets fed to the broodstock. The main fatty acids in both larvae lots during yolksac stage were 16:0, 18:1n-9 and 22:6n-3.The desaturation index Δx = [P + Σ (n - x) - Σ (n - x) diet]/P allowed the determination of the relative importance of the Δ9, Δ6, Δ5 and Δ4 desaturations during the egg and larval yolksac stages.The levels of total lipid fatty acids in eggs and larvae during yolksac period were almost constant and very low desaturation and elongation activities were apparent.A competitive inhibition was observed between the fatty acids of the n-6 series with respect to the ones of the n-3 series in those eggs and larvae from broodstock whose diet contained a high proportion of linoleic acid and its derivatives.