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.     

FA composition of cholesteryl esters and phospholipids in maternal plasma during pregnancy and at delivery and in cord plasma at birth

The purpose of this study was to assess the FA composition of both cholesteryl esters (CE) and phospholipids (PL) in maternal plasma during pregnancy and at delivery and in umbilical plasma at birth. A longitudinal study of 32 normal pregnant women was carried out with three cutoff points during pregnancy (first, second, and third trimester) and at delivery. Few significant differences occurred in the FA profile of maternal CE: 18∶1n−9 increased, 18∶2n−6 dropped slightly, and 18∶3n−3 decreased with progressing gestation. In maternal PL, long-chain highly unsaturated FA concentrations dropped and were replaced by saturated FA as gestation progressed. Additionally, changes in saturated FA in PL occurred: Shorter-chain 16∶0 was higher whereas longer-chain 18∶0 was lower at delivery compared to early pregnancy. The FA profile of umbilical venous plasma was strikingly different from that of maternal plasma at delivery. Cord plasma CE contained more saturated and monounsaturated FA than maternal CE. The polyunsaturates 18∶2n−6 and 18∶3n−3 are lower in umbilical CE than in maternal CE whereas 20∶4n−6 and 22∶6n−3 are twice as high in umbilical CE. Cord plasma PL have a higher content of long-chain highly unsaturated FA than maternal plasma PL at delivery. In contrast to maternal plasma PL, 16∶0 was lower and longer-chain saturated FA were higher in cord plasma PL. The FA profile of umbilical plasma at birth shows preferential accumulation of 20∶4n−6 and 22∶6n−3, with low concentrations of 18∶2n−6 and 18∶3n−3 in CE and PL, indicating a preferential supply of the fetus with long-chain highly unsaturated FA needed for fetal development.     

Incorporation of n−3 fatty acids into plasma and liver lipids of rats: Importance of background dietary fat

The health benefits of long-chain n−3 PUFA (20∶5n−3 and 22∶6n−3) depend on the extent of incorporation of these FA into plasma and tissue lipids. This study aimed to investigate the effect of the background dietary fat (saturated, monounsaturated, or n−6 polyunsaturated) on the quantitative incorporation of dietary 18∶3n−3 and its elongated and desaturated products into the plasma and the liver lipids of rats. Female weanling Wistar rats (n=54) were randomly assigned to six diet groups (n=9). The fat added to the semipurified diets was tallow (SFA), tallow plus linseed oil (SFA-LNA), sunola oil (MUFA), sunola oil plus linseed oil (MUFA-LNA), sunflower oil (PUFA), or sunflower oil plus linseed oil (PUFA-LNA). At the completion of the 4-wk feeding period, quantitative FA analysis of the liver and plasma was undertaken by GC. The inclusion of linseed oil in the rat diets increased the level of 18∶3n−3, 20∶5n−3, and, to a smaller degree, 22∶6n−3 in plasma and liver lipids regardless of the background dietary fat. The extent of incorporation of 18∶3n−3, 20∶5n−3, and 22∶5n−3 followed the order SFA-LNA>MUFA-LNA>PUFA-LNA. Levels of 22∶6n−3 were increased to a similar extent regardless of the type of major fat in the rat diets. This indicates that the background diet affects the incorporation in liver and plasma FA pools of the n−3 PUFA with the exception of 22∶6n−3 and therefore the background diet has the potential to influence the already established health benefits of long-chain n−3 fatty acids.     

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.     

Changes in fatty acid composition of plasma and oviduct lipids during sexual maturation of Japanese quail

The fatty acid (FA) compositions of plasma and oviduct phospholipids (PL) and triglycerides (TG) were studied throughout the natural sexual development of the Japanese quail. In the oviduct, PL concentration increased rapidly during the period of active oviduct cell proliferation and then remained at a constant level during the phase of cellular hypertrophy. Oviduct and plasma TG concentrations were 2- and 10-fold higher, respectively, in fully developed animals than in immature ones. During natural sexual maturation of the quail, the FA compositions of PL and TG were markedly modified both in plasma and in oviduct. These qualitative changes occurred predominantly during the period of intense cellular proliferation of oviduct cells, and also were observed in immature animals injected with physiological doses of estradiol. In oviduct PL, the proportions of 20∶4n−6 and 22∶4n−6 decreased significantly (from 20 to 10% and 3.5 to 0.7%, respectively) whereas those of 18∶2n−6 increased (from 8.5 to 21%). In contrast, the plasma PL proportions of 20∶4n−6, 22∶4n−6 and 18∶2n−6 were decreased significantly and the percentage of 18∶1n−9 doubled, suggesting that the oviduct is able to utilize certain plasma FA to a greater extent than others. Changes in plasma and oviduct lipid composition occurring in the quail during sexual development may be attributed to estradiol, which stimulates hepatic Δ9 desaturase and inhibits the oviduct Δ6 desaturase. The changes in FA composition observed in oviduct phospholipids are discussed in relation to eicosanoid production and cellular proliferation.     

Composition and structure of triacylglycerols in brown adipose tissue of rats fed fish oil

This study examines the incorporation of highly unsaturated n−3 fatty acids (HUFA) into triacylglycerols (TAG) of brown adipose tissue (BAT), and their effect on the positional distribution of saturated (SFA) and of unsaturated (UFA) 16- or 18-carbon fatty acids. To this end, rats were fed a fish oil diet for up to four weeks. The stereospecific analysis of TAG was based on generation ofsn-1,2- andsn-2,3-acylglycerols by Grignard degradation, followed by synthesis of phosphatidic acid and specific hydrolysis with phospholipase A₂. From the end of the first week of fish oil feeding, a steady-state in the fatty acid composition of TAG in BAT was reached. HUFA concentration increased 30-fold, mainly at the expense of n−9 UFA and of SFA. The amount of SFA decreased selectively at position 3, where these fatty acids were progressively replaced by n−3 HUFA. By contrast, the amount of UFA decreased at all positions, and their positional distribution was not affected. About 60% of HUFA was incorporated at position 3. Nearly twice as much 22∶6n−3 was incorporated into TAG than had been previously observed in white adipose tissue (WAT) [Leray, C., Raclot, T., and Groscolas, R. (1993)Lipids 28, 279–284]. At the steady-state, the distribution of HUFA was characterized by high proportions of 22∶6n−3 and 20∶5n−3 in position 3. Moreover, in each position of TAG, a steady level was reached rapidly (within 1 wk). It is concluded that, during fish-oil feeding, fatty acids in TAG of BAT show characteristic time-course changes that lead to a characteristic composition and a tissue-specific positional distribution. This suggests that adipose tissue has its own specificity in controlling the build-up of TAG stores, which is likely to be regulated by the specificity of acylating enzymes as well as molecular rearrangements.     

The composition of saturated fatty acids in plasma phospholipids changes in a way to counteract changes in the mean melting point during pregnancy

It has been demonstrated that in pathological conditions with an increase in the calculated mean melting point (MMP) of phospholipid (PL) fatty acids (FA) there are changes in the composition of the saturated FA (SFA), which partially counteract this effect: shorter-chain SFA with lower melting points are increased, while longer-chain less fluid SFA are suppressed. The aim of this study was to determine whether there are differences in MMP during pregnancy and in the newborn and, if so, whether similar adaptive changes occur in the composition of the SFA The FA composition of plasma PL was determined in healthy women (n-16) twice during pregnancy (15–24 wk and 29–36 wk) and at delivery and in umbilical venous blood obtained at birth. The MMP of maternal PL was significantly higher at delivery compared to mid-gestation, due to a loss of highly unsaturated FA (HUFA) which were replaced by SFA. In addition, changes in the SFA occurred; 16∶0 with lower melting point was higher while 18∶0 with higher melting point was lower at delivery. MMP of PL FA in umbilical plasma was lower than in maternal plasma at delivery, which was due to higher HUFA content. In contrast to maternal plasma, 16∶0 was lower while 18∶0, 20∶0 and 24∶0 were higher in umbilical plasma resulting in a higher MMP of SFA, tending to raise the overall MMP. It can be concluded that, during pregnancy and in the newborn, the FA composition of SFA changes in a way to counteract changes in MMP induced by reduced and increased HUFA, respectively.     

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.     

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.     

Comparison of the effects of dietary alpha-linolenic,stearidonic, and eicosapentaenoic acids on production of inflammatory mediators in mice

The effects of dietary stearidonic acid (18∶4n−3) on inflammatory mediator release in whole blood and splenocytes was investigated in Balb/c mice, and the effects were compared with those of two other n−3 PUFA: α-linolenic acid (18∶3n−3) and EPA (20∶5n−3). TAG mixtures containing 10% of 18∶4n−3, 18∶3n−3, or 20∶5n−3 as the respective sole n−3 PUFA were enzymatically synthesized. Diets containing synthesized TAG mixtures were fed to Balb/c mice for 3 wk. The release of prostaglandin E₂ (PGE₂) and tumor necrosis factor (TNF) were measured in whole blood and splenocytes stimulated with lipopolysaccharide. In whole blood, the production of INF was suppressed by all dietary n−3 PUFA (18∶3n−3, 18∶4n−3, and 20∶5n−3) as compared with the control diet, which contained TAG prepared from safflower oil. PGE₂ production was not significantly changed. Differences among the n−3 PUFA (18∶3n−3), 18∶4n−3, and 20∶5n−3) were not observed. In splenocytes, PGE₂ production was suppressed by dietary n−3 PUFA, but TNF production was not. GC analysis of plasma and splenocyte FA profiles showed an increase in the levels of 20∶4n−3, 20∶5n−3, and 22∶6n−3 in mice fed the diet containing 18∶4n−3.     

Supplementation and delivery of n−3 fatty acids through spray-dried milk reduce serum and liver lipids in rats

Indian diets comprising staples such as cereals, millets, and pulses provide 4.8 energy % from linoleic acid (18∶2n−6) but fail to deliver adequate amounts of n−3 FA. Consumption of long-chain n−3 PUFA such as EPA (20∶5n−3) and DHA (22∶6n−3) is restricted to those who consume fish. The majority of the Indian population, however, are vegetarians needing additional dietary sources of n−3 PUFA. The present work was designed to use n−3 FA-enriched spray-dired milk powder to provide n−3 FA. Whole milk was supplemented with linseed oil to provide α-linolenic acid (LNA, 18∶3n−3), with fish oil to provide EPA and DHA, or with groundnut oil (GNO), which is devoid of n−3 PUFA, and then spray-dired. Male Wistar rats were fed the spray-dired milk formulations for 60 d. The rats given formulations containing n−3 FA showed significant increases (P<0.001) in the levels of LNA or EPA/DHA in the serum and in tissue as compared with those fed the GNO control formulation. Rats fed formulations containing n−3 FA had 30–35% lower levels of serum total cholesterol and 25–30% lower levels of serum TAG than control animals. Total cholesterol and TAG in the livers of rats fed the formulations containing n−3 FA were lower by 18–30% and 11–18%, respectively, compared with control animals. This study showed that spray-dried milk formulations supplemented with n−3 FA are an effective means of improving dietary n−3 FA intake, which may decrease the risk factors associated with cardiovascular disease.     

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.     

Lipids and FA analysis of canine prostate tissue

It is widely reported that an association exists between dietary fat intake and the incidence of prostate cancer in humans. To study this association, there is a need for an animal model where prostate carcinogenesis occurs spontaneously. The canine prostate is considered a suitable experimental model for prostate cancer in humans since it is morphologically similar to the human prostate and both humans and dogs have a predisposition to benign and malignant prostate disease. In this study, the FA and lipids profiles of the normal canine prostate tissue from nine dogs were examined. The total lipid content of the canine prostate tissue was 1.7±0.5% (wet weight). The lipid composition analysis using TLC-FID showed that the two major lipid classes were phospholipids and TAG. Total FA, phospholipid, and TAG FA analysis showed that the major FA were palmitic acid (16∶0), stearic acid (18∶0), oleic acid (18∶1), linoleic acid (18∶2n−6), and arachidonic acid (20∶4n−6), The n−3 FA were present at <3% of total FA and included α-linolenic acid (18∶3n−3) (in total and TAG tissue FA), EPA (20∶5n−3) (not in TAG), and DHA (22∶6n−3) (not in TAG). The n−3/n−6 ratio was 1∶11, 1∶13, and 1∶8 in total, phospholipid, and TAG FA, respectively. This study shows the canine prostate has a low level of n−3 FA and a low n−3/n−6 ratio. This is perhaps due to low n−3 content of the diet of the dogs. FA analysis of dogfoods available in Australia showed that the n−3 content in both supermarket and premium bran dogfoods was <3% (wet weight), and the n−3/n−6 ratio was low.     

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.     

Effect of dietary α-linolenic acid and its ratio to linoleic acid on platelet and plasma fatty acids and thrombogenesis

The effect of dietary α-linolenic acid (18∶3n−3) and its ratio to linoleic acid (18∶2n−6) on platelet and plasma phospholipid (PL) fatty acid patterns and prostanoid production were studied in normolipidemic men. The study consisted of two 42-d phases. Each was divided into a 6-d pre-experimental period, during which a mixed fat diet was fed, and two 18-d experimental periods, during which a mixture of sunflower and olive oil [low 18∶3n−3 content, high 18∶2/18∶3 ratio (LO-HI diet)], soybean oil (intermediate 18∶3n−3 content, intermediate 18∶2/18∶3 ratio), canola oil (intermediate 18∶3n−3 content, low 18∶2/18∶3 ratio) and a mixture of sunflower, olive and flax oil [high 18∶3n−3 content, low 18∶2/18∶3 ratio (HI-LO diet)] provided 77% of the fat (26% of the energy) in the diet. The 18∶3n−3 content and the 18∶2/18∶3 ratio of the experimental diets were: 0.8%, 27.4; 6.5%, 6.9; 6.6%, 3.0; and 13.4%, 2.7, respectively. There were appreciable differences in the fatty acid composition of platelet and plasma PLs. Nevertheless, 18∶1n−9, 18∶2n−6 and 18∶3n−3 levels in PL reflected the fatty acid composition of the diets, although very little 18∶3n−3 was incorporated into PL. Both the level of 18∶3n−3 in the diet and the 18∶2/18∶3 ratio were important in influencing the levels of longer chain n−3 fatty acid, especially 20∶5n−3, in platelet and plasma PL. Production of 6-keto-PGF_1α was significantly (P<0.05) higher following the HI-LO diet than the LO-HI diet although dietary fat source had no effect on bleeding time or thromboxane B₂ production. The present study showed that both the level of 18∶3n−3 in the diet and its ratio to 18∶2n−6 were important in influencing long-chain n−3 fatty acid levels in platelet and plasma PL and that prostanoid production coincided with the diet-induced differences in PL fatty acid patterns.     

Relationship between platelet phospholipid FA and mean platelet volume in healthy men

Increased mean platelet volume (MPV) has been suggested as an independent risk factor for acute myocardial infarction and the increased reactivity of large platelets. The aim of this study was to investigate the correlation between platelet phospholipid (PL) PUFA composition and MPV in 139 free-living healthy men ages 20–55 yr (vegans, n=18; ovolacto vegetarians, n=43; modrerate meat-eaters, n=60; and high meateaters, n=18). Each subject completed a semiquantitative Food Frequency Questionnaire and gave a blood sample. Platelet PL FA composition and MPV were determined by standard methods. MPV was significantly greater in the vegans than in the ovolacto vegetarian, moderate, or high meat-eater groups (P<0.01). Both vegan and ovolacto vegetarian groups had significantly higher platelet PL 18∶2n−6 and 22∶4n−6, and lower 20∶5n−3 and 22∶6n−3 compared with the moderate and high meat-eater groups. The vegans demonstrated a significant reduction in 20∶4n−6 and 22∶5n−3 compared with the ovolacto vegetarian, high meat-eater, and moderate meat-eater groups. Bivariate analysis results showed that MPV was significanly positively correlated with platelet PL 18∶2n−6 (P=0.048) and negatively correlated with 20∶3n−6 (P=0.02), 20∶5n−3 (P=0.005), and 22∶5n−3 (P<0.0001), respectively. In a multiple linear regression analysis, after controlling for potential confounding factors such as dietary group, age exercise, body mass index, and dietary polyunsaturated and saturated fat, cholesterol, carbohydrate, and fiber intake, the MPV was still strongly negatively correlated with platelet PL 20∶3n−6 (P=0.003) and 22∶5n−3 (P=0.001). The present data suggest that 20∶5n−3 and 20∶3n−6 may play a role in the structural function of the platelet membrane.     

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.     

Dietary menhaden, seal, and corn oils differentially affect lipid and Ex vivo eicosanoid and thiobarbituric acid-reactive substances generation in the guinea pig

This investigation was carried out to characterize the effects of specific dietary marine oils on tissue and plasma fatty acids and their capacity to generate metabolites (prostanoids, lipid peroxides). Young male guinea pigs were fed nonpurified diet (NP), or NP supplemented (10%, w/w) with menhaden fish oil (MO), harp seal oil (SLO), or corn oil (CO, control diet) for 23 to 28 d. Only the plasma showed significant n−3 polyunsaturated fatty acid (PUFA)-induced reductions in triacylglycerol (TAG) or total cholesterol concentration. Proportions of total n−3 PUFA in organs and plasma were elevated significantly in both MO and SLO dietary groups (relative to CO), and in all TAG fractions levels were significantly higher in MO-than SLO-fed animals. The two marine oil groups differed in their patterns of incorporation of eicosapentaenoic acid (EPA). In guinea pigs fed MO, the highest levels of EPA were in the plasma TAG, whereas in SLO-fed animals, maximal incorporation of EPA was in the heart polar lipids (PL). In both marine oil groups, the greatest increases in both docosahexaenoic acid (22∶6n−3, DHA) and docosapentaenoic acid (22∶5n−3, DPA) relative to the CO group, were in plasma TAG, although the highest proportions of DHA and DPA were in liver PL and heart TAG, respectively. In comparing the MO and SLO groups, the greatest difference in levels of DHA was in heart TAG (MO>SLO, P<0.005), and in levels of DPA was in heart PL (SLO>MO, P<0.0001). The only significant reduction in proportions of the major n−6 PUFA, arachidonic acid (AA), was in the heart PL of the SLO group (SLO>MO=CO, P<0.005). Marine oil feeding altered ex vivo generation of several prostanoid metabolites of AA, significantly decreasing thromboxane A₂ synthesis in homogenates of hearts and livers of guinea pigs fed MO and SLO, respectively (P<0.04 for both, relative to CO). Lipid peroxides were elevated to similar levels in MO- and SLO-fed animals in plasma, liver, and adipose tissue, but not in heart preparations. This study has shown that guinea pigs respond to dietary marine oils with increased organ and plasma n−3 PUFA, and changes in potential synthesis of metabolites. They also appear to respond to n−3 PUFA-enriched diets in a manner that is different from that of rats.     

FA composition of plasma,red blood cell,and liver phospholipids of newborn piglets fed trans isomers of alpha-linolenic acid

The effects of dietary cis and trans α-linolenic acid (18∶3n−3) on the FA composition of plasma, red blood cell, and liver phospholipids were studied in newborn piglets. Animals were fed for 14 d with one of three diets: a control diet (group A) containing cis 18∶3n−3 at a level of 2.0% of total FA, a diet (group B) in which a part of the 18∶3n−3 acid was isomerized (1.3% of cis 18∶3n−3 and 0.7% of trans 18∶3n−3), or a diet (group C) with 2.0% cis 18∶3n−3 and 0.7% trans 18∶3n−3. Feeding animals with diets containing trans 18∶3n−3 resulted in the presence of trans isomers of 18∶3n−3, trans isomers of EPA, and trans isomers of DHA in phospholipids; however, the level of total trans n−3 PUFA in tissues was less than 0.3% of total tissue FA. In group B, the reduction of dietary amounts of cis 18∶3n−3 was associated with a decrease in individual and total cis n−3 PUFA. In contrast, in group C there was no decrease in tissue n−3 PUFA despite the increased dietary level of trans 18∶3n−3. These results suggest that the isomerization of a part of dietary n−3 PUFA, leading to the reduction of their levels in the diet, could induce a decrease in n−3 PUFA in phospholipids. The physiological effects of trans PUFA are not known and should be considered in future studies.     

Thermal adaptation affects the fatty acid composition of plasma phospholipids in trout

The adaptive changes in the fatty acid (FA) composition of plasma phospholipids (PL) in response to alterations in environmental water temperature were investigated in juvenile rainbow trout (Oncorhynchus mykiss). The changes observed during thermal adaptation from 22°C in summer to 8°C in winter were reproduced by laboratory cold acclimation (CA) at 6°C of 22°C-summer-acclimated animals. In cold-acclimated and winter-acclimated trout, the increase in the unsaturation of PL fatty acids was mainly due to an enrichment of approximately 7% in the total weight percentage of 22∶6n−3, while a concomitant significant decrease in the levels of 18∶0 and of the monoenoic n−9 FA was observed. A time course study revealed that the changes in PL fatty acids became significant after 10 d of CA and were complete after one month. These changes in the composition of the fatty acyl chains of plasma total PL indicate that the FA composition of plasma lipoprotein PL does not remain constant during thermal adaptation. This would suggest that plasma lipoproteins provide a rapid systemic supply of lipids containing more or less unsaturated FA during thermal adaptation of poikilothermic animals.