Distribution of polyunsaturated fatty acids including conjugated linoleic acids in total and subcellular fractions from healthy and cancerous parts of human kidneys

Differences in the FA composition of subcellular fractions from healthy and cancerous kidney tissues from the same patients were examined. Only minor differences in CLA content were found between the healthy and the cancerous tissue portions. Regarding the distribution pattern, CLA incorporation into nuclei and cytosol was significantly higher than incorporation into plasma membranes and mitochondria, which could be correlated to the neutral lipid content of these fractions. The subcellular distribution pattern of CLA was similar to that observed with monounsaturated FA but unlike that found with 18∶2n−6, which underlines the different physiological properties of CLA and 18∶2n−6. Because PUFA have been suggested to have an effect on cancer risk, the contents of n−3 and n−6 PUFA were determined in kidney and renal cell carcinoma (RCC). The 18∶2n−6 content and Δ⁵ desaturase activity were significantly lower, and the 18∶3n−6, 20∶3n−6, and 20∶5n−3 contents and Δ⁶ desaturase activity were significantly higher in RCC than in healthy renal tissue, indicating a changed PUFA metabolism in RCC. Previous research has suggested that CLA inhibits the elongation and desaturation of 18∶2n−6 into 20∶4n−6. In that case, one might speculate that a diet enriched in CLA would be a useful tool in preventing RCC. However, the involvement of CLA in preventing renal cancer could not be demonstrated definitively from the design of this experiment. Further understanding of the cause and/or consequence of the difference in FA metabolism may lead to a better understanding of RCC.     

Composition and seasonal variation of fatty acids of <Emphasis Type="Italic">Diplodus vulgaris</Emphasis> L. from the Adriatic Sea

Muscle tissue from the common two-banded sea bream Diplodus vulgaris L. originating from the Adriatic Sea, Croatia, was analyzed. The FA composition of neutral (TAG) and polar (PE, PC, PI/PS) lipid classes was determined, as well as the lipid and water contents during winter and summer periods. Both the total lipid and water contents were higher in the winter period. We identified 16 different FA. The major constituents of the total FA in both seasons were saturates: palmitic (16∶0) and stearic acids (18∶0); monoenes: oleic (18∶1n−9) and palmitoleic acids (16∶1n−7); and polyunsaturates: arachidonic acid (20∶4n−6), EPA (20∶5n−3), and DHA (22∶6n−3), but their amounts and ratios differed significantly between the two seasons and between lipid fractions. The FA composition showed a noticeable pattern of seasonality that reflected fluctuations mainly in TAG. The diminution of the monounsaturated FA content in the summer was clearly followed by an increase in PUFA content. Diplodus vulgaris is a good source of natural n−3 PUFA and would therefore be suitable for inclusion in highly unsaturated low-fat diets.     

Lipid and FA composition of the pearl oyster <Emphasis Type="Italic">Pinctada fucata martensii</Emphasis>: Influence of season and maturation

The lipid and FA composition of the total lipids of the pearl oyster Pinctada fucata martensii, in different seasons and in different areas, were analyzed to clarify its lipid physiology and to estimate the possible influence of its prey phytoplankton. TAG and sterols were the major components in the neutral lipids in all conditions, whereas high levels of phospholipids (PE and PC) were found in the polar lipids. The major FA in the TAG in all samples were 14∶0, 16∶0, and 18∶0 as saturated FA (saturates); 16∶1n−7, 18∶1n−9, and 18∶1n−7 as monoenoic FA (monoenes); and 20∶4n−6 (arachidonic acid: AA), 20∶5n−3 (EPA), and 22∶6n−3 (DHA) as PUFA. The major components found in the polar lipids were 16∶0 and 18∶0 as saturates; 22∶2n−9, 15 and 22∶2n−7, 15 as non-methylene-interrupted dienes (NMID), and AA, 22∶3n−6, 9, 15, EPA, and DHA as PUFA. Although it is a marine animal, characteristically high levels of AA were found in both the TAG and phospholipids. This result suggests that lipids of P. fucata may be influenced by those of its phytoplanktonic prey. The increase in levels of NMID from TAG to PE with a decrease in those of monoenes suggests that the tissues of this species are able to biosynthesize only the less unsaturated PUFA, such as NMID. In particular, NMID derivatives are considered to be biosynthesized in the PE; thus, they might play a particular role in the membrane, because NMID were characteristically localized only in the PE.     

Effects of geographic source, rearing system, and season on the nutritional quality of wild and farmed Perca fluviatilis

The effects of season, geographic source (Lake Geneva, Rhine River), and rearing system (extensive, semiextensive, and intensive systems) on the lipid content and FA composition of fillets of Perca fluviatilis were studied. Significant differences in the total lipid content were found between fish coming from the Rhine River and Lake Geneva (1.21 and 1.48%, respectively). Seasonal effects were investigated quarterly for perch sampled in the Rhine River. Intensively reared perch displayed a higher lipid content (1.48%) than the other farmed perch, i.e., 1.26% for a semiextensive system and 1.16% for an extensive system. No significant difference in lipid content was found (i) between lacustrine fish and intensively reared fish or (ii) among fish from the Rhine River and the semiextensive or extensive rearing systems. The main FA were 22∶6n−3 (DHA, 21.3–37.1% of total FA), 16∶0 (17.7–20.2%), 20∶5n−3 (EPA, 9.2–13.2%), 18∶1 (8.0–11.5%), 20∶4n−6 [arachidonic acid (ARA), 1.9–10.7%], 16∶1 (4.3–6.0%), and 18∶2n−6 (2.1–6.0%). In comparison with perch coming from the Rhine River, the lacustrine fish were characterized by higher total n−6 PUFA and a lower proportion of both total monounsaturated FA (MUFA) and total n−3 PUFA. Among rearing systems, extensively farmed fish had higher n−6 PUFA and lower n−3 PUFA contents. Wild fish showed higher ARA and 18∶2n−6 than farmed fish. They also had significantly more EPA (12.5–13.2%) than farmed perch (9.2–10.9%). For DHA no difference existed between (i) the lacustrine fish (31.9% of total FA) and the intensively reared fish (33.0%) and (ii) the Rhine (37.1%) and semiextensively reared fish (36%). Effects of size, diet composition, and environmental conditions on the total lipid contents and FA composition are discussed.     

Influence of diet on fatty acids of three subtropical fish, subfamily caesioninae (Caesio diagramma and C. tile) and family siganidae (Siganus canaliculatus)

The total lipid and fatty acid compositions of tissues and the stomach contents of three subtropical marine fish species, subfamily Caesioninae, Caesio diagramma and C. tile, and family Siganidae Siganus canaliculatus, were investigated to clarify the differences between these species. Triacylglycerols (TAG) were the dominant depot lipids of the three species, whereas wax esters were found as a minor component. In particular, muscle lipids were found to contain mainly glycerol derivatives such as TAG and phospholipids. The major fatty acids identified in the three species were 16∶0, 18∶0, 18∶1n−9, and 22∶6n−3 (docosahexaenoic acid, DHA). In addition, noticeable levels of 16∶1n−7, 18∶1n−7, 20∶4n−6 (arachidonic acid, AA), and 20∶5n−3 (eicosapentaenoic acid) were found. DHA was the most abundant polyunsaturated fatty acid (PUFA) in the muscle and viscera lipids of the three species. The high DHA levels in the lipids of all the organs were found to be higher than those of the lipid extracted from the stomach contents of the three fishes. In addition, the specimens of S. canaliculatus contained significantly higher levels of AA in its tissues than did the other two species. A high AA content is unusual since such high levels of n−6 PUFA are rarely found in higher marine organisms. These levels may be due to its characteristic feeding pattern, because S. canaliculatus prefer and mainly feed on seaweed, which often contains high amounts of n−6 PUFA, such as linoleic acid (18∶2n−6) and AA.     

Fatty acids bound to <Emphasis Type="Italic">Fasciola hepatica</Emphasis> 12 kDa fatty acid-binding protein,a candidate vaccine,differ from fatty acids in extracts of adult flukes

The FA composition of Fasciola hepatica 12 kDA purified native FA-binding protein (nFh12), a candidate vaccine against fascioliasis, is described. The FA chain lengths ranged between 12 and 24 carbons. The principal FA were 16∶0 18∶1n−9, 18∶0, 20∶4n−6, and 20∶1n−9. The acids 16∶0, 18∶1n−9, and 18∶0 comprised over half the FA that were bound to the whole FA-binding protein. Small amounts (1.0–2.8%) of isoanteiso methyl-branched FA also were characterized. Forty-one different FA were identified in extracts of the adult flukes, with the three most abundant FA also being 16∶0, 18∶1n−9, and 18∶0. A similar proportion of saturated vs. unsaturated FA was observed between the whole extract from F. hepatica and the nFh12 protein. However, the n−3/n−6 ratio of PUFA was significantly different, being 1.2 in the whole extract vs. 9.6 in the nFh12 protein complex. The nFh12 protein binds more n−5, n−6, and n−7 PUFA and less n−3 and n−9 PUFA than the whole extract. In addition, cholesterol (56%), sitosterol (36%), and fucosterol (8%) also were bound to the nFh12 protein complex.     

Lipid class and fatty acid composition of the boreal soft coral Gersemia rubiformis

Total lipid, phospholipid, and FA composition and distribution of FA between polar lipids (PL) and neutral lipids (NL) were investigated in the boreal soft coral Gersemia rubiformis from the Bering Sea. The total lipids were mostly hydrocarbons and waxes (33.7%) and PL (33.1%). The content of monoalkyldiacylglycerols (9.7%) exceeded the content of TAG (6.7%). PC and PE constituted 31.4% and 25.6% of total phospholipids, respectively. Principal FA were 16∶0, 16∶1n−7, 18∶0, 18∶1n−9, 18∶1n−7, 20∶1n−7, 20∶4n−6, 20∶4n−3, 20∶5n−3 22∶5n−3, 22∶6n−3, 24∶5n−6, and 24∶6n−3. Most n−6 PUFA (52% of total FA) were associated with the PL fraction; this was especially true for arachidonic and tetracosapentaenoic acids. The NL were enriched with mono-, di-, trienoic, and n−3 PUFA. The variation in EPA levels in both NL and PL suggests an origin of this acid from lipids of diatoms consumed by the corals.     

Hepatic lipid characteristics and histopathology of laying hens fed CLA or n−3 fatty acids

The effect of dietary CLA and n−3 PUFA on hepatic TAG accumulation, histopathology, and FA incorporation in lipid classes by laying chickens was investigated. One hundred twenty 30-wk-old single-comb white leghorn laying hens were distributed randomly to four treatments (3 replications of 10 birds) and were fed diets containing CLA and animal fat (Diet I), 18∶3n−3 (Diet II), or long-chain n−3 FA (Diet III). A sunflower oil (n−6 FA)-based diet was the control. Feeding Diet I resulted in an increase in hepatic total lipids (P<0.05). The liver TAG content was 32.2, 18.9, 29.4, and 18.7 mg/g for hens fed Diet I, Diet II, Diet III, and the control diet, respectively (P<0.05). The serum TAG was lowest in bilds fed Diet II (P<0.05). Diet I resulted in an increase in the total number of fat vacuoles and lipid infiltration in hepatocytes (P<0.05). The number of cells with 75% or higher lipid vacuolation was observed only in birds fed Diet I. Feeding diets containing CLA resulted in an increase in the content of the c9,t11 CLA isomer in liver TAG and PC (P<0.05). No difference was observed in the CLA concentration of hepatic PE fractions. The content of DHA (22∶6n−3) was higher in the TAG, PC, and PE of hens fed Diet II and Diet III than Diet I and the control (P<0.05). Feeding CLA resulted in an increase in total saturated FA in the TAG and PC fractions (P<0.05). Long-term feeding of CLA in laying birds leads to an increase in liver TAG and may predispose birds to fatty liver hemorrhagic syndrome.     

Evaluation of two GC columns (60-m SUPELCOWAX 10 and 100-m CP Sil 88) for analysis of milkfat with emphasis on CLA, 18:1, 18:2 and 18:3 isomers,and short- and long-chain FA

Milkfat is a complex mixture of many diverse FA, some of which have demonstrated health benefits including anticancer properties. Attempts are under way to enrich milkfats with long-chain n−3 PUFA and CLA. It has been recommended that the analysis of these milkfats requires gas chromatography (GC) equipped with long, highly polar capillary columns. However, many analyses have been reported using CARBOWAX^TM type (polyethylene glycol) capillary columns, such as SUPELCOWAX 10, even though the separation characteristics of many of the FA and their isomers present in milkfats have not been described in detail. This includes the isomers of CLA, cis- and trans-octadecenoic acid (18∶1), linoleic acid (18∶2n−6), and linolenic acid (18∶3n−3), and the long-chain PUFA. On the other hand, the resolution of these FA and their isomers has been more fully described using the highly polar capillary columns, such as CP Sil 88 and SP2560 because of the improved resolution obtained using these polar columns. The present study was undertaken to characterize the separation of these FA present in milkfats using a 60-m SUPELCOWAX 10 column, to compare the results to those from a 100-m CP Sil 88 column, and to determine if these two columns could possibly serve to complement each other for the analysis of total milkfat. The advantages of the SUPELCOWAX 10 column were a better resolution of the short-chain saturated from their monounsaturated FA (MUFA) analogs, and a complete separation of the α-linolenic (18∶3n−3) and eicosadecenoic acid (20∶1) isomers. It also provided an alternative elution order of the linoleic (18∶2n−6), 18∶3n−3 and γ-linolenic (18∶3n−6) acid isomers. On the other hand, the CP Sil 88 column provided a better resolution of the CLA isomers, MUFA, the isolated cis and trans MUFA fractions, the PUFA, and many the 18∶2n−6 and 18∶3n−3 isomers. A complete analysis of milk lipids using the CP Sil 88 column required the prior separation of total FAME using silver ion-TLC. The results of the present study confirm that the 100-m highly polar capillary GC columns are mandatory for the analysis of milk lipids, and at best, the 60 m SUPELCOWAX 10 capillary column serves as a complementary GC column to provide different separations in certain regions based on its intermediate polarity.     

Gas chromatography-chemical ionization-mass spectrometric fatty acid analysis of a commercial supercritical carbon dioxide lipid extract from New Zealand green-lipped mussel (Perna canaliculus)

Supercritical fluid extracts of New Zealand green-lipped mussels (NZGLM) have been suggested to have therapeutic properties related to their oil components. The large number of minor FA in NZGLM extract was characterized by a GC-CIMS/MS method that excels at identification of double-bond positions in FAME. The extract contained five major lipid classes: sterol esters, TAG, FFA, sterols, and polar lipids. The total FA content of the lipid extract was 0.664 g/mL. Fifty-three unsaturated FA (UFA) were fully identified, of which 37 were PUFA, and a further 21 UFA were detected for which concentrations were too low for assignment of double-bond positions. There were 17 saturated FA, with 14∶0, 16∶0, and 18∶0 present in the greatest concentration. The 10 n−3 PUFA detected included 20∶5n−3 and 22∶6n−3, the two main n−3 FA; n−3 PUFA at low concentrations were 18∶3, 18∶4, 20∶3, 20∶4, 21∶5, 22∶5, 24∶6, and 28∶8. There were 43 UFA from the n−4, n−5, n−6, n−7, n−8, n−9, n−10, n−11 families, with 16∶2n−4, 16∶1n−5, 18∶1n−5, 18∶2n−6, 20∶4n−6, 16∶1n−7, 20∶1n−7, 16∶1n−9, 18∶1n−9, and 20∶1n−9 being the most abundant. In general, we estimated that FAME concentrations greater than 0.05% (w/w) were sufficient to assign double-bond positions. In total, 91 FA were detected in an extract of the NZGLM, whereas previous studies of fresh flesh from the NZGLM had reported identification of 42 FA. These data demonstrate a remarkable diversity of NZGLM FA.     

Conjugated linoleic acids alter bone fatty acid composition and reduce ex vivo prostaglandin E2 biosynthesis in rats fed n-6 or n-3 fatty acids

This study evaluated the effects of conjugated linoleic acids (CLA) on tissue fatty acid composition and ex vivo prostaglandin E₂ (PGE₂) production in rats given diets varying in n-6 and n-3 fatty acids. Four groups of rats were given a basal semipurified diet (AIN-93G) containing 70 g/kg of added fat for 42 d. The fat treatments were formulated to contain CLA (0 vs. 10 g/kg of diet) and n-6 (soybean oil having an n-6/n-3 ratio of 7.3) and n-3 fatty acids (menhaden oil+safflower oil having an n-6/n-3 ratio of 1.8) in different ratios in a 2×2 factorial design. Fatty acids in liver, serum, muscle, heart, brain, spleen, and bone (cortical, marrow, and periosteum) were analyzed by capillary gas-liquid chromatography. The various dietary lipid treatments did not affect growth; however, CLA improved feed efficiency. The CLA isomers were found in all rat tissues analyzed although their concentrations varied. Dietary CLA decreased the concentrations of 16∶1n−7, 18∶1, total monounsaturates and n−6 fatty acids, but increased the concentrations of n−3 fatty acids (22∶5n−3 and 22∶6n−3), and saturates in the tissues analyzed. Ex vivo PGE₂ production in bone organ culture was decreased by n−3 fatty acids and CLA. We speculate that CLA reduced the concentration of 18∶1 fatty acids by inhibiting liver Δ9-desaturase activity. The fact that CLA lowered ex vivo PGE₂ production in bone organ culture suggests that these conjugated fatty acids have the potential to influence bone formation and resorption.     

A significant inverse relationship between concentrations of plasma homocysteine and phospholipid docosahexaenoic acid in healthy male subjects

The aim of this study was to investigate the possibility of a relationship between plasma homocysteine (Hcy) and phospholipid FA (PUFA) in healthy Australian males. One hundred thirty six healthy male subjects aged 20–55 yr were recruited from the Melbourne metropolitan area. Each volunteer completed a semiquantitative food frequency questionnaire and gave a blood sample. Plasma Hcy concentrations were determined by an established HPLC method; the plasma phospholipid FA were determined by standard methods. Plasma Hcy concentration was significantly negatively correlated with plasma phospholipid concentration of the PUFA 20∶5n−3 (r=−0.226, P=0.009), 22∶5n−3 (r=−0.182, P=0.036), 22∶6n−3 (r=−0.286, P=0.001), total n−3 (r=−0.270, P=0.002) and the ratio n−3/n−6 PUFA (r=−0.265, P=0.002), and significantly positively correlated with 20∶4n−6 (r=0.180, P=0.037). In the partial correlation analysis, after controlling for serum vitamin B₁₂ and folate concentration, plasma Hcy was significantly negatively correlated with the plasma phospholipid concentration of 22∶6n−3 (r=−0.205, P=0.019), total n−3 (r=−0.182, P=0.038) and the ratio n−3/n−6 PUFA (r=−0.174, P=0.048). Evidence indicates that an increased concentration of n−3 PUFA in tissues has a beneficial effect on cardiovascular health. Our findings provide further evidence that increased consumption of dietary n−3 PUFA increases the concentration of n−3 PUFA in plasma phospholipid, which is associated with a protective effect on cardiovascular diseases and lower plasma Hcy levels. The mechanism that might explain the association between plasma 22∶6n−3 and Hcy levels is not clear.     

Effects of red wine consumption on kidney FA composition

We studied the effects of red wine consumption on the FA composition of rat kidney. Four groups of adult male rats were fed a balanced diet for 10 wk. The drinking fluid was water (control), red wine, alcohol-free red wine, or ethanol (12.5%, vol/vol). FA composition, lipid peroxidation, and cytochrome P450 content were determined in the kidney. The antioxidant capacity of plasma was also measured. Ethanol decreased the content of long-chain PUFA, whereas red wine maintained the levels of arachidonic (20∶4n−6) and eicosapentaenoic (20∶5n−3) acids and alcohol-free red wine significantly increased the levels of 20∶4n−6. Lipid peroxidation in the red wine and alcohol-free red wine groups was significantly lower than that of both the control and ethanol groups. The diminished renal lipid peroxidation was associated with an increased antioxidant capacity of plasma. Renal cytochrome P450 was elevated by 50% in the ethanol group and diminished by 20% in the alcohol-free red wine group. These data suggest that moderate red wine consumption could contribute to the preservation of the contents of n−3 and n−6 PUFA, particularly 20∶4n−6, in rat kidney. Although ethanol increased the content of cytochrome P450 in the kidney, this effect was eliminated by the nonalcoholic components of red wine.     

Phospholipid fatty acyl distribution of three fungi indicates positional specificity for n-6vs. n-3 fatty acids

Phospholipids of the fungiConidobolus nanodes, Entomophthora exitalis andSaprolegnia parasitica were extracted and analyzed. The phospholipid content was the same (2.4%) for the three species and was independent of the total lipid content. Phospholipase A₂ degradation of individual phospholipid classes showed an asymmetrical distribution of polyunsaturated fatty acids (PUFA) between the two fatty acyl positions of glycerol. There was a predominance of n-6 PUFA at position 2 and a predominance of n-3 PUFA at position 1. WithC. nanodes andE. exitalis, 20∶5n−3 is derived from 18∶3n−3 and is located predominantly at position 1. InS. parasitica 20∶5n−3 is synthesized from 18∶3n−6via 20∶4n−6 and is located predominantly at position 2. It is suggested that the asymmetrical distribution of PUFA between positions 1 and 2 of glycerol Points towards different sites of synthesis of the two classes of PUFA, and that cross-over between PUFA of the different types is prevented by thesn-1 orsn-2 positional specificity of the desaturases.     

Influence of diet on fatty acids and tocopherols in M. Longissimus Dorsi from reindeer

Our aim was to compare the effects of two pelleted diets containing differing FA composition with natural lichen pasture on reindeer's meat FA composition. In addition we wanted to increase the knowledge about reindeer FA metabolism and the effect of animal sex and age on FA composition in reindeer muscle. The trial included five reindeer groups: three grazing, consisting of adult males, adult females, and calves; and two groups of calves fed conventional pellets (CPD) and pellets containing crushed linseed (LPD), respectively, for two months before slaughter. Differences between male and female animals were mainly found in the neutral lipid fraction and related to fatness. Calves differed significantly from adult males and females in FA and lipid class composition. CPD led to a higher ratio of n−6 to n−3 FA compared with grazing. The ratio n−6/n−3 in the polar lipid (PL) fraction of the animals fed LPD was slightly, but not significantly, higher than that in the grazing reindeer. LPD-fed animals had lower proportions of long-chain polyunsaturated FA (LCPUFA), namely 20∶4n−6, 22∶5n−3, and 22∶6n−3, in the PL fraction compared with the grazing animals due to the content of these FA in the natural feed. The animals seemed unable to elongate dietary FA in significant amounts. We conclude that by adding crushed linseed to the pellets it was possible to keep the favorable FA composition of meat from grazing reindeer with regard to the n−6/n−3 ratio but not in LCPUFA.     

Identification of minor fatty acids and various nonmethylene-interrupted diene isomers in mantle,muscle, and viscera of the marine bivalve Megangulus zyonoensis

To clarify the occurrence of nonmethylene-interrupted (NMI) FA in the marine bivalve Megangulus zyonoensis, methyl esters of unsaturated FA were fractionated according to the degree of their unsaturation by using argentation TLC. Their structures were elucidated by using GC-MS of their FAME and 2-alkenyl-4,4-dimethyloxazoline derivatives. Seventy-two unsaturated FA, including the novel 7,15–21 and 20∶4n−1, were identified. The unusual tetraenoic acids 20∶4n−4, 20∶4n−1, 21∶4n−6, and 21∶4n−5 were found in M. zyonoensis. This bivalve was extremely rich in the positional isomers of 19∶1, 20∶2, and 20∶3. The distribution of NMI and positional isomers of unusual FA in the bivalve tissues was also discussed.     

The lipid composition of selected tissues from a Mediterranean monk seal,Monachus monachus

The lipid composition of blubber, brain, muscle and heart from a Mediterranean monk sealMonachus monachus (an endangered species) were examined to allow comparisons with more common species of seals. Only neutral lipids (mainly triacylglycerols) were detectable in the blubber lipids, whereas polar lipids predominated in the heart and in the brain. Neutral and polar lipids comprised almost equal proportions in both liver and muscle. Choline glycerophospholipids (CGP) were the major polar lipids, followed by ethanolamine glycerophospholipids (EGP) in the liver, heart and muscle. Cerebrosides accounted for 28.8% of the brain lipids. All lipid classes of the liver contained high levels (31–47%) of polyunsaturated fatty acids (PUFA), with the exception of phosphatidylserine. The total proportion of n−6 PUFA exceeded that of n−3 PUFA in all lipid classes of the liver, due mainly to the high levels of 20∶4n−6. The highest level of 20∶4n−6 occurred in phosphatidylinositol, where it comprised 32.4% of the total fatty acids. The CGP and EGP of the brain contained lower levels of PUFA than those of the liver, muscle and heart. Alkenyl ethers accounted for 35.8% of the total long-chain moieties in brain EGP. The fatty acid composition of blubber triacylglycerols differed from those of the lipid classes from other tissues in that it had a very low ratio of n−6 to n−3 PUFA (0.3) as a result of a lower content of 20∶4n−6.     

Dietary fish oil dose-response effects on ileal phospholipid fatty acids and contractility

We have reported that dietary fish oil (FO) leads to the incorporation of long-chain n−3 PUFA into the gut tissue of small animal models, affecting contractility, particularly of rat ileum. This study examined the FO dose response for the incorporation of n−3 PUFA into ileal tissue and how this correlated with in vitro contractility. Groups of ten to twelve 13-wk-old Wistar-Kyoto rats were fed 0, 1, 2.5, and 5% FO-supplemented diets balanced with sunflower seed oil for 4 wk, after which ileal total phospholipid FA were determined and in vitro contractility assessed. For the total phospholipid fraction, increasing the dietary FO levels led to a significant increase first evident at 1% FO, with a stepwise, nonsaturating six-fold increase in n−3 PUFA as EPA (20∶5n−3), DPA (docosapentaenoic acid, 22∶5n−3), and DHA, but mainly as DHA (22∶6n−3), replacing the n−6 PUFA linoleic acid (18∶2n−6) and arachidonic acid (20∶4n−6) over the dosage range. There was no difference in KCl-induced depolarization-driven contractility. However, a significant increase in receptor-dependent maximal contractility occurred at 1% FO for carbachol and at 2.5% FO for prostaglandin E₂, with a concomitant increase in sensitivity for prostaglandin E₂ at 2.5 and 5% FO. These results demonstrate that significant increases in ileal membrane n−3 PUFA occurred at relatively low doses of dietary FO, with differential receptor-dependent increases in contractility observed for muscarinic and prostanoid agonists.     

Fatty acid profiles and relative mobilization during fasting in adipose tissue depots of the American marten (Martes americana)

The American marten (Martes americana) is a boreal forest marten with low body adiposity but high metabolic rate. The study describes the FA composition in white adipose tissue depots of the species and the influence of food deprivation on them. American marten (n=8) were fasted for 2 d with 7 control animals. Fasting resulted in a 13.4% weight loss, while the relative fat mass was >25% lower in the fasted animals. The FA composition of the fat depots of the trunk was quite similar to other previously studied mustelids with 14∶0, 16∶0, 18∶0, 16∶1n−7, 18∶1n−9, and 18∶2n−6 as the most abundant FA. In the extremities, there were higher proportions of monounsaturated FA (MUFA) and PUFA. Food deprivation decreased the proportions of 16∶0 and 16∶1n−7, while the proportion of long-chain MUFA increased in the trunk. The mobilization of FA was selective, as 16∶1n−7, 18∶1n−9, and particular n−3 PUFA were preferentially mobilized. Relative mobilization correlated negatively with the carbon chain length in saturated FA (SFA) and n−9 MUFA. The Δ9 desaturation of SFA enhanced the mobilization of the corresponding MUFA, but the positional isomerism of the first double bond did not correlate consistently with relative mobilization in MUFA or PUFA. In the marten, the FA composition of the extremities was highly resistant to fasting, and the tail tip and the paws contained more long-chain PUFA to prevent the solidification of lipids and to maintain cell membrane fluidity during cooling.     

Changes in phosphatidylcholine molecular species in the shrimp <Emphasis Type="Italic">Macrobrachium borellii</Emphasis> in response to a water-soluble fraction of petroleum

The effect of the water-soluble fraction (WSF) of crude oil on lipid contents, lipid classes, FA, and PC molecular species was studied in high-phospholipid (hepatopancreas) and low-phospholipid (egg) tissues of a freshwater crustacean. After a 21-d exposure to a sublethal concentration of WSF, a significant decrease in shrimp total lipids was observed, although no alterations could be detected in the hepatopancreas or egg lipid contents. TAG/phospholipid ratios increased in the hepatopancreas and decreased in the eggs, suggesting alterations either in the mobilization of TAG to phospholipid pools or in the energy balance. The FA composition of phosphoglycerides in the hepatopancreas and eggs was dominated by PUFA, whereas the n−3/n−6 ratio was not affected by WSF exposure, although there was a significant increase in hepatopancreas 18∶1n−9. Analysis of the PC molecular species by HPLC-ELSD showed the presence of 15 species, with 16∶0/18∶1, 18∶1/18∶2, 16∶0/20∶5, and 16∶1/20∶5 being the major species in the hepatopancreas. The PC molecular species in the eggs showed a different pattern, dominated by 16∶0/18∶1 and 18∶1/18∶2. Of the PC molecular species, 10 contained 22∶6n−3, 20∶5n−3, and 20∶4n−6. Small amounts of di-PUFA species were also found. Exposure to WSF altered the PC molecular species in both tissues. The four major hepatopancreas molecular species and most of the ones containing PUFA decreased. This was compensated for by an increase in 16∶1/18∶1 (152%) and 18∶1/18∶1 (50%). The two major egg PC molecular species decreased, whereas the PUFA-containing ones increased. The contrasting responses of both tissues of WSF contamination suggests the presence of different homeostatic mechanisms.