Fatty-Acid Profile of Total and Polar Lipids in Cultured Rainbow Trout (Oncorhynchus mykiss) Raised in Freshwater and Seawater (Croatia) Determined by Transmethylation Method

Fatty acids from total lipids and polar lipids in cultured rainbow trout (Oncorhynchus mykiss) raised in seawater (SW) and freshwater (FW) were identified and quantified from the muscle samples in January, April, and July. The highest total lipid and polar lipid amounts were found in April. July contents of total lipids were low, but percent of the polyunsaturated fatty acids (PUFAs) was high in SW and FW environment (particularly n-3 PUFAs). Variety of 17 fatty acids was identified by GC-FID after transmethylation. The predominant fatty acids in rainbow trout from SW and FW were: docosahexaenoic acid among n-3 PUFAs, palmitic acid among saturated fatty acids (SFAs), and oleic acid among monounsaturated fatty acids (MUFAs). Appreciably higher n-3/n-6 ratio was found in total lipids in April (6.40, FW fish) and in polar lipids in July (18.76; SW fish). High n-3/n-6 ratio in total lipids and polar lipids of rainbow trout from SW and FW, besides beneficial n-3/n-6 ratio in the commercial fish food, could be characteristic for the local environmental conditions (Croatia).     

Rearing system and oleic acid supplementation effect on carcass and lipid characteristics of two muscles from an obese pig breed

Quality of pork depends on genotype, rearing and pre- and post-slaughter conditions. However, no information is available on rearing system changes and oleic acid supplementation on carcass characteristics and fatty acid (FA) profile of pork from the Alentejano (AL) pig, an obese breed. This study evaluates the effects of feeding low (LO) or high oleic acid diets (HO) to AL pigs reared in individual pens (IND) or outdoor (OUT) with access to pasture. Carcass composition was obtained and longissimus dorsi and semimembranosus samples were collected to analyse chemical composition and neutral and polar intramuscular lipids FA profile by gas chromatography. Statistical analysis was performed by a two-way ANOVA for rearing system and diet effects. OUT-reared pigs presented leaner carcasses than IND-reared ones. Both muscles presented lower intramuscular lipid content in OUT-reared pigs. Treatments affected the FA profile of muscles. Overall, OUT-reared pigs presented lower n-6/n-3 FA ratios, whereas pigs fed the HO diet exhibited lower saturated fatty acids (SFA), higher monounsaturated fatty acids (MUFA) levels and lower thrombogenic indexes on neutral intramuscular lipids than LO-fed pigs. On the polar fraction, OUT-reared pigs presented lower SAT and n-6/n-3 FA ratio, and higher polyunsaturated fatty acids (PUFA) levels on both muscles. Pigs fed the HO diet exhibited higher MUFA and lower PUFA levels on both muscles, and lower SAT levels on semimembranosus. This study shows rearing system and oleic acid supplementation have complementary effects and influence carcass composition and the nutritional quality of meat.     

Plasma and muscle phospholipids are involved in the metabolic response to long-distance migration in a shorebird

We studied: (1) concentrations and fatty acid compositions of plasma non-esterified fatty acids, neutral lipids, and phospholipids, and (2) fatty acid composition of flight muscle phospholipids in wintering, premigratory, and spring and fall migrating western sandpipers ( Calidris mauri). Plasma neutral lipid and phospholipid levels were elevated in migrants, reflecting high rates of fat deposition. An important role of phospholipids in fattening is suggested by the fact that the amount of fatty acids in plasma phospholipids was similar to, or in spring as much as twice, that of neutral lipids. Changes in the ratio of plasma neutral lipids to phospholipids may indicate seasonal changes in triacylglycerol stores of invertebrate prey. Monounsaturation and total unsaturation of plasma neutral lipids and phospholipids increased during migration. Muscle phospholipids were more monounsaturated in spring and fall, but total unsaturation was reduced in fall. Arachidonic acid [20:4(n-6)] was especially abundant in muscle phospholipids in winter (29%) and declined during migration (19-22%), contributing to a decline in the ratio of n-6 to n-3 fatty acids. The abundance of plasma phospholipids and variability of neutral lipid to phospholipid ratio indicates that measurement of plasma phospholipids will improve methods for assessment of fattening rates of birds. The functional significance of changes in muscle phospholipids is unclear, but may relate to depletion of essential n-6 fatty acids during exercise.     

Fatty Acid Transport and Utilization for the Developing Brain

Abstract: To determine the transport and utilization of dietary saturated, monounsaturated, and n-6 and n-3 polyunsaturated fatty acids for the developing brain and other organs, artificially reared rat pups were fed a rat milk substitute containing the perdeuterated (each 97 atom% deuterium) fatty acids, i.e., palmitic, stearic, oleic, linoleic, and linolenic, from day 7 after birth to day 14 as previously described. Fatty acids in lipid extracts of the liver, lung, kidney, and brain were analyzed by gas chromatography-mass spectrometry to determine their content of each of the deuterated fatty acids. The uptake and metabolism of perdeuterated fatty acid lead to the appearance of three distinct groups of isotopomers: the intact perdeuterated, the newly synthesized (with recycled deuterium), and the natural unlabeled fatty acid. The quantification of these isotopomers permits the estimation of uptake and de novo synthesis of these fatty acids. Intact perdeuterated palmitic, stearic, and oleic acids from the diet were found in liver, lung, and kidney, but not in brain. By contrast, perdeuterated linoleic acid was found in all these organs. Isotopomers of fatty acid from de novo synthesis were observed in palmitic, oleic, and stearic acids in all tissues. The highest enrichment of isotopomers with recycled deuterium was found in the brain. The data indicate that, during the brain growth spurt and the prelude to myelination, the major saturated and monounsaturated fatty acids in brain lipids are exclusively produced locally by de novo biosynthesis. Consequently, the n-6 and n-3 polyunsaturated fatty acids must be transported and delivered to the brain by highly specific mechanisms.     

Dynamics of fatty acid composition of total lipids during embryonic development of Atlantic salmon Salmo salar L

Dynamics of fatty acid composition of total lipids was studied for freshwater salmon Salmo salar L. during its embryonic development from blastula (3 hours) up to hatching (108 days) as well as in unfertilized eggs. Stable amount of total and some saturated, monounsaturated and polyunsaturated fatty acids (PUFA) of total lipids was observed during embryonic development. Considerable changes in fatty acid composition were observed at the stage of prelarvae hatching, i.e., significant decrease of (n-6) PUFA (18:2(n-6) and 20:4(n-6)) and (n-3) PUFA and increase of total and some saturated and monounsaturated fatty acids was registered. Change in saturation ratio of membrane lipids justifies the presence of the biochemical mechanism forwarded on regulation of cell membrane enzymes in accordance with the changes of internal physiological processes taking place in the organism and fluctuations of external environmental conditions or the preparation period (as reproduction). Data on peculiarities of transformation and utilization of fatty acids during salmon embryonic development may be used for understanding of their functional role in the developing organism as well as for assessing the quality of the caviar.     

Dynamics of fatty acid composition of total lipids during embryonic development of atlantic salmon <Emphasis Type="Italic">Salmo salar</Emphasis> L.

Dynamics of fatty acid composition of total lipids was studied for freshwater salmon Salmo salar L. during its embryonic development from blastula (3 hours) up to hatching (108 days) as well as in unfertilized eggs. Stable amount of total and some saturated, monounsaturated and polyunsaturated fatty acids (PUFA) of total lipids was observed during embryonic development. Considerable changes in fatty acid composition were observed at the stage of prelarvae hatching, i.e., significant decrease of (n-6) PUFA (18:2(n-6) and 20:4(n-6)) and (n-3) PUFA and increase of total and some saturated and monounsaturated fatty acids was registered. Change in saturation ratio of membrane lipids justifies the presence of the biochemical mechanism forwarded on regulation of cell membrane enzymes in accordance with the changes of internal physiological processes taking place in the organism and fluctuations of external environmental conditions or the preparation period (as reproduction). Data on peculiarities of transformation and utilization of fatty acids during salmon embryonic development may be used for understanding of their functional role in the developing organism as well as for assessing the quality of the caviar.     

Variations in the biochemical composition of the squid Illex argentinus from the South Atlantic Ocean

General condition, biochemical composition changes and fatty acids in several tissues of I. argentinus at different sexual stages were studied. Ovarian maturation involves a simultaneous increase in ovary mass and in protein and lipid levels. Testes weights were modified less than the ovary with maturation and showed a constant biochemical composition during spermatogenesis. The digestive gland grew through most of the maturation process in both sexes. Water level was high in immature squid and low in mature females and males, and varied inversely to that of lipids. Dorsal mantle maintained a constant biochemical composition, between February (immature) and June (fertilized females and mature males). All tissues contained high concentration of polyunsaturated fatty acids followed by saturated fatty acids and monosaturated fatty acids. This digestive gland of the squid is rich in polyenoic fatty acids, 20:5n-3 and 22:6n-3. This tissue could be a cheap raw material, presently discarded, for production of polyunsaturated fatty acids.     

Metabolism of palmitic and docosahexaenoic acids in Reuber H35 hepatoma cells

In this work, we have modified the fatty acid composition of Reuber H35 hepatoma cells by supplementation of the culture medium with a saturated (palmitic) or a polyunsaturated (docosahexaenoic) acid. These fatty acids were incorporated into total lipids and phospholipids of hepatoma cells. Palmitic acid readily increased the percentage of its monounsaturated derivative (16:1 n-7). When both fatty acids were supplemented at the same concentration, the percentage of docosahexaenoic acid in the total lipids and phospholipids of Reuber H35 cells increased more than that of palmitic acid. Although the levels of 16:0 increased, the addition of docosahexaenoic acid to the culture medium decreased the percentages of monoenoic acids. From our results, it can be concluded that palmitic and docosahexaenoic acids modify the fatty acid composition of Reuber H35 hepatoma cells. The profound changes induced by docosahexaenoic acid, especially those in the phospholipid fraction, may be of great interest given the main role of these components in the regulation of chemical and physical properties of biological membranes and/or membrane systems.     

Lipids and fatty acids of two pelagic cottoid fishes (Comephorus spp) endemic to Lake Baikal

Matured females of two Lake Baikal endemic fish species, Comephorus baicalensis and Comephorus dybowski, have been investigated for lipid of the whole body and specific tissues (liver, muscles, ovaries), phospholipid classes and fatty acids of neutral and polar lipids. Total lipid in the body (38.9% fresh weight), liver (23.5%) and muscles (14.5%) of C. baicalensis were greater than those of C. dybowski (4.7, 8.7 and 2.6%, respectively); only their ovaries were similar (5.3 and 5.6% lipid, respectively). In both species, phosphatidylcholine and phosphatidylethanolamine were the major phospholipids, ranging from 60.7 to 75.1% of total phospholipid and 14.5–25.7%, respectively. In most cases, monounsaturated fatty acids (MUFA) were the major fatty acid group in C. baicalensis, whereas polyunsaturated fatty acids (PUFA) were the major group in C. dybowski. The MUFA 18:1(n-9) prevailed over other fatty acids in C. baicalensis and varied from 19% in polar lipids of muscles to 56.1% in neutral lipids of muscles. In polar lipid of C. dybowski, the PUFA 22:6(n-3) prevailed over other fatty acids in muscles and ovaries, while 16:0 dominated polar liver lipids and neutral lipids of all tissues. Other major fatty acids included 16:1(n-7), 18:1(n-7), and 20:5(n-3). Values of the (n-3)/(n-6) fatty acid ratio for neutral lipids of C. baicalensis (0.5–0.9) are well below the range of values characteristic either for marine or freshwater fish, while these values for polar lipids (1.6–1.8) are in the range typical of freshwater fish. Neutral lipid fatty acid ratios in C. dybowski (2.5–3.1) allow it to be assigned to freshwater fish, but polar lipids (2.8–3.7) leave it intermediary between freshwater and marine fish.     

Analysis of interspecific variation in relative fatty acid composition: use of flow cytometry to estimate unsaturation index and relative polyunsaturated fatty acid content in microalgae

Relative polyunsaturated fatty acid content and unsaturation index are very important composition variables in the use of microalgae both for animal and human nutrition and biofuel production. A readily available technique to rapidly and inexpensively estimate relative fatty acid composition is very important for mass screening of new strains for the production of different types of oil. This study demonstrates the validity of Nile Red staining and flow cytometry for quick estimation of unsaturation index and relative fatty acid content in microalgae. Nile Red staining allows polar and neutral lipid contents to be estimated, and in this study a significant correlation was observed between polar/neutral ratio and fatty acid content in the species studied, corresponding to higher polyunsaturated fatty acid content in the polar lipid fraction of microalgae. This technique enables quick estimation of relative polyunsaturated fatty acid content and interspecific variation, as well as variations caused by culture conditions. In the species studied, most variability in fatty acid composition was due to variation in monounsaturated and polyunsaturated fatty acids, with less variation observed in saturated fatty acid content.     

Fatty acid composition of platelet phospholipids and plasma lipids in obese Zucker rats

The purpose of this work was to see whether hyperlipaemia observed in genetically obese Zucker rats (fa/fa) was associated with differences in fatty-acid composition of plasma triacylglycerols, plasma phospholipids and of platelet phospholipids, in comparison with the control lean rats (Fa/-). Results showed that plasma triacylglycerols and phospholipids were increased in obese rats. In triacylglycerols, the amount of saturated and monounsaturated fatty acids was highly increased whereas the amount of the n-6 and n-3 polyunsaturated fatty acids was little modified. In plasma phospholipids, saturated and monounsaturated fatty acids were also increased, as were the n-3 fatty acids (except C 18:3 n-3); the n-6 fatty acids were little increased except C 20:3 n-6 which was markedly increased. These results concerning the amounts of fatty acids have their counterpart in their relative proportions of fatty acids. Data thus obtained suggest that conversion of linoleic acid (C 18:2 n-6) into arachidonic acid (C 20:4 n-6) was decreased in obese rats, particularly the delta 5 desaturation step. On the contrary, conversion of linolenic acid (C 18:3 n-3) into higher polyenes seemed increased. Thrombocytosis was not modified in the obese rat, but the volume of the platelets was increased. Platelet phospholipids exhibited the same modifications as plasma phospholipids but with different magnitude. Saturated and monounsaturated fatty acids were little augmented, n-3 fatty acids were more augmented (except C 18:3 n-3 acid which was unchanged); n-6 fatty acids were not modified except C 20:3 n-6 acid which was highly increased.(ABSTRACT TRUNCATED AT 250 WORDS)     

Seasonal changes in lipid classes and fatty acid composition in the digestive gland of Pecten maximus

Seasonal variations in lipid classes and fatty acid composition of triacylglycerols and phospholipids in the digestive gland of Pecten maximus were studied over a period of 16 months. Acylglycerols predominated (19-77% of total lipids), in accordance with the role of the digestive gland as an organ for lipid storage in scallops. Seasonal variations were mainly seen in the acylglycerol content, while phospholipids (2.5-10.0% of total lipids) and sterols (1.9-7.4% of total lipids) showed only minor changes. The most abundant fatty acids were 14:0, 16:0, 18:0, 16:1(n-7), 18:1(n-9), 18:1(n-7), 18:4(n-3), 20:5(n-3) and 22:6(n-3) and these showed similar seasonal profiles in both, triacylglycerol and phospholipid fractions. In contrast to the phospholipid fraction, the triacylglycerol fraction contained more 20:5(n-3) than 22:6(n-3). In three phospholipid samples we noted a high percentage of a 22-2-non-methylene-interrupted fatty acid, previously described to have a structural role in several bivalve species. The main polyunsaturated fatty acids displayed important seasonal variations parallel to those of the acylglycerols, suggesting good nutritional conditions. A positive correlation existed between the level of saturated fatty acids and temperature, whereas the levels of polyunsaturated fatty acids correlated negatively with temperature.     

Monounsaturated fatty acyl-coenzyme A is predictive of atherosclerosis in human apoB-100 transgenic, LDLr-/- mice

ACAT2, the enzyme responsible for the formation of cholesteryl esters incorporated into apolipoprotein B-containing lipoproteins by the small intestine and liver, forms predominantly cholesteryl oleate from acyl-CoA and free cholesterol. The accumulation of cholesteryl oleate in plasma lipoproteins has been found to be predictive of atherosclerosis. Accordingly, a method was developed in which fatty acyl-CoA subspecies could be extracted from mouse liver and quantified. Analyses were performed on liver tissue from mice fed one of four diets enriched with one particular type of dietary fatty acid: saturated, monounsaturated, n-3 polyunsaturated, or n-6 polyunsaturated. We found that the hepatic fatty acyl-CoA pools reflected the fatty acid composition of the diet fed. The highest percentage of fatty acyl-CoAs across all diet groups was in monoacyl-CoAs, and values were 36% and 46% for the n-3 and n-6 polyunsaturated diet groups and 55% and 62% in the saturated and monounsaturated diet groups, respectively. The percentage of hepatic acyl-CoA as oleoyl-CoA was also highly correlated to liver cholesteryl ester, plasma cholesterol, LDL molecular weight, and atherosclerosis extent. These data suggest that replacing monounsaturated with polyunsaturated fat can benefit coronary heart disease by reducing the availability of oleoyl-CoA in the substrate pool of hepatic ACAT2, thereby reducing cholesteryl oleate secretion and accumulation in plasma lipoproteins.     

Uptake and incorporation of saturated and unsaturated fatty acids into macrophage lipids and their effect upon macrophage adhesion and phagocytosis.

Murine thioglycollate-elicited peritoneal macrophages were cultured in the presence of a variety of fatty acids added as complexes with bovine serum albumin. All fatty acids tested were taken up readily by the cells and both neutral and phospholipid fractions were enriched with the fatty acid provided in the medium. This generated a range of cells enriched in saturated, monounsaturated or polyunsaturated fatty acids, including n-3 acids of fish oil origin. Saturated fatty acid enrichment enhanced macrophage adhesion to both tissue culture plastic and bacterial plastic compared with enrichment with polyunsaturated fatty acids. Macrophages enriched with the saturated fatty acids myristate or palmitate showed decreases of 28% and 21% respectively in their ability to phagocytose unopsonized zymosan particles. Those enriched with polyunsaturated fatty acids showed 25-55% enhancement of phagocytic capacity. The greatest rate of uptake was with arachidonate-enriched cells. Phagocytic rate was highly correlated with the saturated/unsaturated fatty acid ratio, percentage of polyunsaturated fatty acid and index of unsaturation, except for macrophages enriched with fish-oil-derived fatty acids; they showed lower phagocytic activity than expected on the basis of their degree of unsaturation. These results suggest that membrane fluidity is important in determining macrophage adhesion and phagocytic activity. However, in the case of phagocytosis, this effect may be partially overcome if the cells are enriched with fish-oil-derived fatty acids. Thus it may be possible to modulate the activity of cells of the immune system, and so an immune response, by dietary lipid manipulation.     

Incorporation and modification of dietary fatty acids in gill polar lipids by two bivalve species Crassostrea gigas and Ruditapes philippinarum

Two bivalve species Crassostrea gigas and Ruditapes philippinarum were fed eight weeks with three mono-specific algae diets: T-Isochrysis galbana, Tetraselmis suecica, Chaetoceros calcitrans, selected on the basis of their polyunsaturated fatty acid (PUFA) composition. The incorporation and the modification of dietary fatty acids in C. gigas and R. philippinarum gill lipids were analysed and compared. Essential PUFA (20:4n-6, 20:5n-3 and 22:6n-3) and non-methylene interrupted PUFAs (known to be synthesised from monounsaturated precursors) contents of gill polar lipid of both species were greatly influenced by the dietary conditioning. Interestingly, oysters and clams responded differentially to the mono-specific diets. Oysters maintained higher 20:5n-3 level and higher 22:2j/22:i and n-7/n-9 ratio in gill polar lipids than clams. To better discriminate dietary and species influences on the fatty acid composition, a Principal Component Analysis followed by a MANOVA on the two most explicative components was performed. These statistical analyses showed that difference in fatty acid compositions attributable to species were just as significant as the diet inputs. The differences of gill fatty acid compositions between oysters and clams are speculated to result of an intrinsic species characteristic and perhaps of a group characteristic: Fillibranch vs. Eulamellibranch.     

Seasonal variation in lipid and fatty acid composition of ice algae from the Barents Sea

The fatty acid compositions of neutral lipid, glycolipid and phospholipid fractions from ice algae sampled from the Barents Sea in spring and autumn were examined for seasonal differences. The ice-algal assemblages were dominated by diatoms. In spring, Nitzschia frigida was the most common species whereas resting stages of Thalassiosira bioculata and Actinocyclus cf curvatulus predominated in autumn. With the exception of one spring sample, neutral lipids predominated over glycolipids and phospholipids in all algal samples. The lipid fractions displayed characteristic fatty acid compositions. In the spring samples the major fatty acids of the neutral lipid fraction were 16:0, 16:1(n-7) and 20:5(n-3) whilst the glycolipid fraction was characterised by higher levels of 20:5(n-3) and C16 polyunsaturated fatty acids, particularly 16:4(n-1). Phospholipids contained higher levels of 22:6(n-3) than the other two lipid fractions although 20:5(n-3) was still the major polyunsaturated fatty acid. In the autumn samples, the neutral lipid fraction contained higher proportions of saturated fatty acids and 16:1(n-7) than the two polar lipid fractions and 22:6(n-3) was most abundant in phospholipids. As with the spring samples, 20:5(n-3) was the major polyunsaturated fatty acid in all lipid fractions of the autumn algae. Overall, the fatty acid compositions of the lipid fractions from spring and autumn algal samples were similar and are consistent with diatoms being the predominant group in the ice algae studied. The high level of neutral lipids observed in both spring and autumn samples suggests that the production of neutral lipids is characteristic of ice algae regardless of season. Nevertheless, some species-specific differences in lipid production may exist since the neutral lipid content of autumn samples containing mainly A. curvatulus was substantially higher than those in which T. bioculata predominated. Received: 26 September 1997 / Accepted: 12 January 1998     

Different fatty acid composition in central and peripheral adipose tissues of the American mink (Mustela vison)

Fatty acid (FA) composition in the intraabdominal (IAB), subcutaneous (SC) and peripheral adipose tissues of the semiaquatic American mink (Mustela vison) was examined in comparison to the diet by gas-liquid chromatography. There was a clear compositional gradient from the IAB via SC to peripheral adipose tissues and the anatomically different adipose tissues accumulated or metabolized FA selectively. The total lipids of the body appendages had smaller proportions of saturated (SFA) and larger proportions of monounsaturated (MUFA) and polyunsaturated fatty acids (PUFA) than the lipids of the trunk adipose tissues. Especially n-3 PUFA were enriched in the periphery. The appendages were also characterized with a high ratio of unsaturated FA to SFA, an increased Delta9-desaturation index and increased mean numbers of double bonds and carbon atoms in a FA molecule. The proportions of SFA and MUFA of the diet resembled the trunk adipose tissues while the dietary percentage of n-3 PUFA surpassed those of the trunk fat depots but was lower than those of the peripheral fats. These data confirm that the FA signatures of mammals reflect not only their dietary history but also metabolic modifications of ingested FA.     

Fatty Acid Composition of Endoneurium and Perineurium from Adult Rat Sciatic Nerve

Reports on lipid composition of peripheral nervous system have generally been restricted to the saturated fatty acids of the endoneurium. In this work we attempt to determine the fatty acid composition of the different lipid classes in both endo- and perineurium from sciatic nerve microdissection on adult rats. Unsaturated fatty acids were found to make up around 60% of total fatty acids in samples of endoneurium and perineurium, with monounsaturated fatty acids forming 40-50% of total unsaturated fatty acid content. Although the same fatty acids were present in both tissues there was a striking difference in C 18:1 (n-9) and C 18:2 (n-6) ratio between endoneurium and perineurium, which is particularly rich in linoleic acid. The nonpolar perineurial lipids were found to be richest in linoleic acid. Phospholipids were present in the perineurium, and they contained high proportions of saturated and medium-chain monounsaturated fatty acids.     

Fatty acid composition in the central and peripheral adipose tissues of the sable (Martes zibellina)

Fatty acid composition was examined in the total lipids of the intraabdominal, subcutaneous and peripheral (paws, tail, nose) adipose tissues of a terrestrial mustelid, the sable Martes zibellina. The species inhabits the Palearctic taiga and is exposed to extreme cold during the winter. Although the paw pads and nose of the sable had higher proportions of total polyunsaturated fatty acids (PUFAs) compared to the adipose tissues of the trunk, the location of fat had only a little influence on the total percentages of saturated and monounsaturated fatty acids in the species. In this respect, the sable differs from its relative, the semiaquatic American mink Mustela vison, which has pronounced unsaturation of lipids towards the periphery. As observed previously in the mink, the sable deposits preferentially n-3 PUFAs in the appendages. The gradient of unsaturation is more modest in the sable possibly due to its terrestrial lifestyle. The results of the present study demonstrate that the average unsaturation of adipose tissue fatty acids does not increase towards the periphery in all northern mammals.     

The levels of essential unsaturated fatty acids in human milk on the 3rd, 4th, 5th, and 6th days after labour

The composition of fatty acids in human milk lipids was determined in 41 women on the 3rd, 4th, 5th and 6th days after labour by the method of gas chromatography. In these investigations no significant differences were demonstrated in the fatty acids in the lipid fractions between these consecutive days. The level of polyunsaturated fatty acids of the n-6 and n-3 groups was about 11.9-13.6%, including linoleic acid (18:2, n-6) about 7.7-9.8%, and alpha-linolenic acid (18:3, n-3) about 0.7-1%. In the analysis group of n-6 fatty acids the determined acids were: linoleic acid (18:2, n-6), gamma-linolenic acid (18:3, n-6), eicosadienoic acid (20:2, n-6), eicosatrienoic acid (20:3, n-6), arachidonic acid (20:4, n-6), docosahexaenoic acid (22:6, n-6). From the group of n-3 acids the identified ones were: alpha-linolenic acid (18:3, n-3), eicosapentaenoic acid (20:5, n-3), docosapentaenoic acid (22:5, n-3) and docosahexaenoic acid (22:6, n-3). The obtained quotients of fatty acids n-6 through n-3 on the consecutive days were: 7.2:1-7.8:1, indicating a too low level of the n-3 acids in the investigated milk. The acids prevailing in human milk lipids were: oleic (18:1, n-9) and palmitic (16:0) which accounted for 37-39% and 25-26% respectively. The polyunsaturated to saturated fatty acid ratio (P:S) ranged from 0.28 to 0.33.