Main phospholipids and their fatty acid composition in muscle and cephalothorax of the edible Mediterranean crustacean Palinurus vulgaris (spiny lobster)

The total lipids of muscle and cephalothorax of Mediterranean lobster Palinurus vulgaris were found to be 1.0% and 2.4% of the wet tissue of which the phospholipids represented 66.5% and 47.5%, respectively. The main PhL saturated, monounsaturated and polyunsaturated fatty acids in muscle and cephalothorax were C16:0, C18:0, C18:1ω-9, C18:1ω-7, C20:4ω-6, C20:5ω-3 and C22:6ω-3. 2-OH C14:0 and cyclo-17:0 fatty acids were also identified though in low percentages. The main individual PhL in muscle were found to be phosphatidylcholine (53.5%), 72.0% of which corresponded to the structure of 1,2-diacyl-glycerocholine while the rest 28.0% to 1-O-alkyl-2-acyl-glycerocholine or 1-O-(1-alkenyl)-2-acyl-glycerocholine and phosphatidylethanolamine (19.3%), 75.0% of which corresponded to the structure of 1,2-diacyl-glyceroethanolamine and 25% to 1-O-alkyl-2-acyl-glyceroethanolamine or 1-O-(1-alkenyl)-2-acyl-glyceroethanolamine. Cephalothorax main PhL were found to be PC and PE (66.4% and 18.8%, respectively). In muscle and cephalothorax PC ω-3 fatty acids amounted 7.78% and 8.60%, while in PE amounted 30.77% and 23.65% respectively. Furthermore, in both tissues PhL, cardiolipine phosphatidylserine, phosphatidylinositol, sphingomyelin and lysophosphatidylcholine, were also found.     

Distribution of omega-3 and omega-6 fatty acids in the ether- and ester-linked phosphoglycerides from tissues of the rainbow trout, Salmo gairdneri

1. Data presented here demonstrate that polyunsaturated fatty acids in the phospholipids of rainbow trout tissues are compartmentalized differently than in mammalian tissues. 2. We have determined the distribution of omega-3 (n-3) and omega-6 (n-6) fatty acids in the alkyl-, alk-1-enyl-, and diacyl- subclasses of phosphatidylcholines (PC), phosphatidyl-ethanolamines (PE), phosphatidylinositols (PI), and phosphatidylserines (PS) from gill, kidney and spleen of rainbow trout. 3. Alkyl-linked PC and alk-1-enyl-linked PE were the most abundant ether-containing phospholipids, amounting to 10-15% of each class; no ether-linked PI or PS was detected. 4. C20:4 n-6 was found in high concentrations only in PI; the n-3 fatty acids were found in highest concentration in the ether-linked phospholipids as compared with the diacyl subclasses and C20:5 n-3 was especially prevalent in 1-O-alk-1'-enyl-2-acyl-sn-glycero-3-phosphoethanolamine and C22:6 n-3 was prevalent in PS.     

Incorporation into phospholipid classes and metabolism via desaturation and elongation of various 14C-labelled (n-3) and (n-6) polyunsaturated fatty acids in trout astrocytes in primary culture

The incorporation and metabolism of [1-14C]18:3(n-3), [1-14C]20:5(n-3), [1-14C]18:2(n-6), and [1-14C]20:4(n-6) were studied in primary cultures of trout brain astrocytes. There were no significant differences between the amounts of individual fatty acids incorporated into total lipid at 22 degrees C, with greater than 90% of all the fatty acids being incorporated into polar lipid classes. The distributions of 18:2(n-6), 18:3(n-3), and 20:5(n-3) in individual phospholipid classes at 22 degrees C were very similar, with 57-63 and 18-24% being incorporated into phosphatidylcholine and phosphatidylethanolamine, respectively. Approximately equal amounts of 20:4(n-6), approximately 30% of the total, were incorporated into each of phosphatidylcholine, phosphatidylethanolamine, and phosphatidylinositol. The metabolism of the (n-3) fatty acids to longer-chain and more unsaturated species was significantly greater than that of (n-6) acids, but delta 4-desaturase activity was very low. A culture temperature of 10 degrees C increased the incorporation of all the fatty acids into total lipid and that of C20 fatty acids into polar lipid. At 10 degrees C, the incorporation of C20 fatty acids into phosphatidylethanolamine and phosphatidylinositol was increased, and the incorporation into phosphatidylcholine and phosphatidylserine was decreased. The distribution of C18 fatty acids was unchanged at the lower temperature, as was the desaturation and elongation of all the polyunsaturated fatty acids incorporated.     

Endogenous phospholipids of swine liver: effect of fat deprivation on molecular species of phosphatidylcholine and phosphatidylethanolamine

Three 1-yr-old swine and two 2.5-wk-old swine were fed a fat-free diet for 1 month and 5 months, respectively. The hepatic phosphatidylcholine and phosphatidylethanolamine were fractionated by silver ion thin-layer chromatography. A distinctive feature of the chromatographic procedure was the development of the chromatograms at low temperatures: -10 degrees C for phosphatidylcholine and 4 degrees C for phosphatidylethanolamine. The chromatographic fractions were hydrolyzed with phospholipase A(2), and the fatty acids were characterized. Significant concentrations of odd-chain saturated and unsaturated fatty acids were found in the swine deprived of fat for 5 months. The major molecular species of phosphatidylcholine in both groups contained monoenoic fatty acids: 16:0/18:1(n - 9), 18:0/18:1(n - 9), and 18:1(n - 9)/18:1(n - 9). Their concentrations changed only slightly with the diet. The molecular species of phosphatidylethanolamine were more sensitive to dietary changes. In the swine deprived of fat for 1 month, about 50% of the molecular species of phosphatidylethanolamine contained tetraenoic fatty acids: 16:0/20:4(n - 6), 18:0/20:4(n - 6), and 18:1(n - 9)/20:4(n - 6). The phosphatidylethanolamine of animals deprived of fat for 5 months contained only 3% molecular species with tetraenoic acids, 18:0/20:4(n - 6), but 36% molecular species with trienoic acids: 18:0/20:3(n - 9), 18:1(n - 9)/20:3(n - 9), 18:0/19:3(n - 8), 16:0/20:3(n - 9), and 17:0/20:3(n - 9). Doubly unsaturated species, such as 18:1(n - 9)/18:1(n - 9), 18:1(n - 9)/20:3(n - 9), and 18:1(n - 9)/20:4(n - 6), were found in both groups of swine, although their total concentrations were higher in the group deprived of fat for a longer period.     

Proximate composition, fatty acids, cholesterol, minerals in frozen red porgy

The proximate composition of frozen red porgy (Pagrus pagrus) was determined. The moisture, ash, protein and total lipids (45.5+/-1.4% PL of which 90.4+/-2.0% PhL) were found to be 71.7+/-1.0%, 1.73+/-0.12%, 21.5+/-0.8% and 0.81+/-0.09% of the wet muscle tissue, respectively. 16:0 and 18:0 were the main SFA, 18:1 (omega-9 and omega-7) the main MUFA while DHA, EPA and arachidonic acid were the main polyunsaturated fatty acids (PUFA). The SFA/PUFA ratio was 1.5 and the omega-3/omega-6 ratio was 3.02. The cholesterol content was found to be 8.18+/-0.34 mg/100 g of the wet muscle tissue. Ni, Cr, Mn, Cu, Zn, Fe and Mg were determined in the muscles, skin, hepatopancreas and head of the fish. The covering percentage of the recommended daily allowance/intake (RDA/RDI) for each mineral, in the muscle tissue, has been calculated to 14.2% (males) and 7.89% (females) for Fe, 2.87% for Cu, 4.07% for Zn 0.4% for Mn, 13.9% for Ni, 20.2% for Cr and 10.4% for Mg.     

Effects of hypothyroidism on the distribution and fatty acyl composition of phospholipids in sarcoplasmic reticulum of fast skeletal muscle of the rat

The distribution of phospholipids and fatty acyl composition of individual phospholipids in sarcoplasmic reticulum from fast skeletal muscle of hypothyroid and euthyroid (control) rats have been determined. Hypothyroidism resulted in a 24% decrease in the phosphatidylethanolamine (PE) content and a concomitant increase in the phosphatidylcholine (PC) content of the sarcoplasmic reticulum. The amounts of other phospholipids and cholesterol remained unaffected. Fatty acyl compositions of PE and PC were quantitatively different, but hypothyroidism affected these compositions similarly. Changes included an increase in the proportions of docosahexaenoic (22:6(n - 3)), arachidonic (20:4(n - 6)), icosatrienoic (20:3(n - 6)) and stearic (18:0) acids and a decrease in those of linoleic (18:2(n - 6)), palmitic (16:0) and oleic (18:1(n - 9)) acids. The effects of hypothyroidism on the phospholipid distribution could be reversed by treatment of hypothyroid animals with thyroid hormone for a period of 14 days (10 micrograms T3/100 g body weight per 2 days). The fatty acyl composition of the phospholipids was also restored to the euthyroid values by this treatment. Exceptions were 18:2 and 22:6 in PE, in which case reversal was significant but not complete, and 18:2, 20:4 and 22:6 in PC. The levels of these acids in PC were not reversed to the euthyroid values after the 14-day treatment, but rather the opposite occurred.     

22-Carbon polyenoic acids. Incorporation into platelet phospholipids and the synthesis of these acids from 20-carbon polyenoic acid precursors by intact platelets

The types of unsaturated fatty acids found in platelet phospholipids must be regulated by a series of controls which include specificity for activation and acylation as well as modification of circulating fatty acids by platelets prior to incubation into phospholipids. In this study we show that washed human platelets not only incorporate [1-14C]6,9,12-18:3, [1-14C]6,9,12,15-18:4, [1-14C]5,8,11-20:3, [1-14C]5,8,11,14-20:4, and [1-14C]5,8,11,14,17-20:5 into their phospholipids but also chain elongate each of these acids with subsequent acylation of the chain elongated products into phospholipids. Platelets incubated alone with 1-14C-labeled 5,8,11-20:3, 5,8,11,14-20:4, 5,8,11,14,17-20:5, 7,10,13,16,19-22:5, or 4,7,10,13,16,19-22:6 incorporated each of these acids into individual phosphoglycerides with phosphatidylinositol having the highest specific activity followed by phosphatidylcholine with phosphatidylserine approximately equal to phosphatidylethanolamine. The incorporation specificity of 4,7,10,13,16,19-22:6 was atypical since it was a relatively poor substrate for acylation into all phospholipids except phosphatidylethanolamine. The 20-carbon acids were better substrates for incorporation into phospholipids than were the 22-carbon compounds. Simultaneous incubation of 10 microM [1-14C]5,8,11,14-20:4 with increasing levels (5 to 15 microM) of each of the above five other 1-14C-labeled acids showed a concentration-dependent increase in the amount of the second fatty acid incorporated into platelet phospholipids. Dietary fat modification thus has the potential of increasing the plasma pool of 22-carbon acids for incorporation into platelets. In addition the activation of 20-carbon eicosanoid precursors by the high affinity platelet activating enzyme (Wilson, D. B., Prescott, S. M. and Majerus, P. W. (1982) J. Biol. Chem. 257, 3510-3515) will yield an acyl-CoA for both acylation and chain elongation followed by subsequent incorporation of 22-carbon acids into phosphoglycerides.     

Essential fatty acid metabolism in cultured human airway epithelial cells.

To characterize essential fatty acid metabolism of human airway epithelium, we examined the capacity of epithelial cells to incorporate and desaturate/elongate 18:2(n - 6) and the turnover of phospholipid fatty acyl chains in these cells. Epithelial cells were cultured for 5-7 days and incubated with [1-14C]18:2(n - 6) (1 microCi, 100 nmol). The essential fatty acid profile of the cells was readily modified by 18:2(n - 6) supplementation to culture medium. After 4 h incubation, 32 +/- 5.6 nmol of [1-14C]18:2(n - 6) was incorporated into phospholipids (65 +/- 9.5%, of which 74% was incorporated into phosphatidylcholine (PC)) and neutral lipid (31 +/- 10%) per mg protein of cultured cells. 30 +/- 8% of [1-14C]18:2(n - 6) incorporated, was converted to homologous trienes, tetraenes and pentaenes, the major products being 20:3(n - 6) and 20:4(n - 6). The conversion of 18:2(n - 6) was time-dependent and donor age-related. A higher proportion of 20:3(n - 6) and 20:4(n - 6) was incorporated into phosphatidylinositol (PI) and phosphatidylethanolamine (PE). About 10-15% of total products formed from 18:2(n - 6) was released from membrane to culture medium. Both 20:4(n - 6) and 20:5(n - 3) inhibited 18:2(n - 6) incorporation and desaturation. Rate of incorporation of 18:2(n - 6) was more than either 18:1(n - 9) or 16:0. With pulse-chase studies, the half-life of 18:2(n - 6) in PC, PI and PE was estimated to be 5.5, 6.0 and 7.3 h, respectively. These data indicate active metabolism of essential fatty acids in human airway epithelial cells. This metabolism may play a key role in the regulation of membrane properties and function in these cells.     

Phospholipid and fatty acid composition in mitochondria from spinach (Spinacia oleracea) leaves and petioles. A comparative study.

Essentially chlorophyll-free mitochondria from photosynthetic (leaf) and non-photosynthetic tissue (petiole) were isolated from spinach (Spinacia oleracea). Leaf mitochondria were found to contain more phosphatidylcholine than phosphatidylethanolamine compared with petiole mitochondria. Galactolipids were found in small and equal amounts (5 mol of galactolipids/100 mol of galactolipids and phospholipids) in both leaf and petiole mitochondria. Fatty acid composition showed a significant difference in the amounts of C18:2 and C18:3 acids. The C18:2/C18:3 ratio was more than twice as high in all of the phospholipids studied from petiole mitochondria compared with the ratio in leaf mitochondria. More than 50% (mol/100 mol) of the fatty acids in the major lipids (phosphatidylcholine, phosphatidylethanolamine and cardiolipin) in petiole mitochondria were C18:2. In the minor lipids (phosphatidylinositol and phosphatidylglycerol), C16:0 dominated in both leaf and petiole mitochondria.     

Phospholipids and fatty acids of Neisseria gonorrhoeae.

The phospholipids and fatty acids of two strains of Neisseria gonorrhoeae of different penicillin susceptibilities were examined. The phospholipids, which comprise about 8% of the dry weight of the cells, consisted of phosphatidylethanolamine (70%) and phosphatidylglycerol (20%); small amounts of phosphatidylcholine and traces of cardiolipin were also present. Growing and stationary-phase cells were similar in content and composition of phospholipids except for phosphatidylcholine, which increased two- to fivefold in the stationary-phase cells. The fatty acids of the phospholipids were characterized by two major acids, palmitic and a C16:1, with myristic and a C18:1 acid present in smaller amounts. The fatty acids present in purified phospholipid fractions varied considerably in relative proportions from fraction to fraction. No significant difference in the composition of phospholipids from the two strains was evident. Large amounts of beta-hydroxy lauric acid were detected only after saponification of the organisms. Differences in the lipid composition between the gonococcus and other gram-negative bacteria are discussed.     

Fatty acid metabolism in Atlantic salmon (Salmo salar L.) hepatocytes and influence of dietary vegetable oil

Isolated hepatocytes from Atlantic salmon (Salmo salar), fed diets containing either 100% fish oil or a vegetable oil blend replacing 75% of the fish oil, were incubated with a range of seven (14)C-labelled fatty acids. The fatty acids were [1-(14)C]16:0, [1-(14)C]18:1n-9, 91-(14)C]18:2n-6, [1-(14)C]18:3n-3, [1-(14)C]20:4n-6, [1-(14)C]20:5n-3, and [1-(14)C]22:6n-3. After 2 h of incubation, the hepatocytes and medium were analysed for acid soluble products, incorporation into lipid classes, and hepatocytes for desaturation and elongation. Uptake into hepatocytes was highest with [1-(14)C]18:2n-6 and [1-(14)C]20:5n-3 and lowest with [1-(14)C]16:0. The highest recovery of radioactivity in the cells was found in triacylglycerols. Of the phospholipids, the highest recovery was found in phosphatidylcholine, with [1-(14)C]16:0 and [1-(14)C]22:6n-3 being the most prominent fatty acids. The rates of beta-oxidation were as follows: 20:4n-6>18:2n-6=16:0>18:1n-9>22:6n-3=18:3n-3=20:5n-3. Of the fatty acids taken up by the hepatocytes, [1-(14)C]16:0 and [1-(14)C]18:1n-9 were subsequently exported the most, with the majority of radioactivity recovered in phospholipids and triacylglycerols, respectively. The major products from desaturation and elongation were generally one cycle of elongation of the fatty acids. Diet had a clear effect on the overall lipid metabolism, with replacing 75% of the fish oil with vegetable oil resulting in decreased uptake of all fatty acids and reduced incorporation of fatty acids into cellular lipids, but increased beta-oxidation activity and higher recovery in products of desaturation and elongation of [1-(14)C]18:2n-6 and [1-(14)C]18:3n-3.     

Characteristics of phospholipids in microvillar membranes of octopus photoreceptor cells.

Characteristics of lipids in the microvillar membranes of octopus photoreceptor cells were studied in order to obtain some information on the membrane environment with rhodopsin in the invertebrate. (1) The membranes contain lipid and protein in almost equal proportion. The majority of lipids are phospholipids. Neutral lipids make up 16% of the total lipids, the major constituent of which is cholesterol. (2) Phosphatidylethanolamine and phosphatidylcholine are the major phospholipids. Phosphatidylserine, ceramide 2-aminoethylphosphonate and sphingomyelin occur as minor components. An unidentified alkaline and acid stable phospholipid was found. (3) The predominant fatty acids of phosphatidylethanolamine and phosphatidylcholine are highly unsaturated such as 22 : 6, 20 : 5 and 20 : 4. The 22 : 6 and 20 : 5 are exclusively linked at the 2-position, but the 20 : 4 is linked significantly at the 1-position of the phospholipids. (4) Major molecular species are 16 : 0/22 : 6 (48.4%) and 16 : 0/20 : 4 (19.6%) in phosphatidylcholine, and 20 : 4/22 : 6 (50.7%) and 16 : 0/22 : 6 (25.6%) in phosphatidylethanolamine.     

The role of defensin fragment in the regulation of fatty acid composition of membrane phospholipids in epithelial-like cells

It is shown that a tetrapeptide fragment of defensin does not alter the phospholipid composition in the membranes of CHO-K1 cells but regulates the fatty acid composition of phosphatidylcholine, phosphatidylethanolamine (PEA), phosphatidylserine (PS), and phosphatidylinositol (PI). Incubation of the cells in the presence of this tetrapeptide resulted in modification of unsaturated fatty acid composition in the studied phospholipids. The content of monoenoic (mainly C18 : 1ω9) and/or dienoic (C18 : 2ω6) fatty acids increased, while the level of polyenoic fatty acids decreased. It was found that in the polyenoic fatty acid group of the PEA, PS and PI molecules, the ω3-/ω6-acid ratio decreased mainly due to the lower content of long-chain ω3-acids with 20 and/or 22 carbonic atoms. The possible role of this peptide in inhibition of the activity of Δ6- and Δ5-desaturases involved in the synthesis of long-chain polyenoic fatty acids, the quantitative alteration of which in phospholipids influences physicochemical parameters in cell membranes, is discussed.     

Astrocytes, Not Neurons, Produce Docosahexaenoic Acid (22:6ω-3) and Arachidonic Acid (20:4ω-6)

Elongated, highly polyunsaturated derivatives of linoleic acid (18:2 omega-6) and linolenic acid (18:3 omega-3) accumulate in brain, but their sites of synthesis are not fully characterized. To investigate whether neurons themselves are capable of essential fatty acid elongation and desaturation or are dependent upon the support of other brain cells, primary cultures of rat neurons and astrocytes were incubated with [1-14C] 18:2 omega-6, [1-14C]20:4 omega-6, [1-14C]18:3 omega-3, or [1-14C]20:5 omega-3 and their elongation/desaturation products determined. Neuronal cultures were routinely incapable of producing significant amounts of delta 4-desaturase products. They desaturated fatty acids very poorly at every step of the pathway, producing primarily elongation products of the 18- and 20-carbon precursors. In contrast, astrocytes actively elongated and desaturated the 18- and 20-carbon precursors. The major metabolite of 18:2 omega-6 was 20:4 omega-6, whereas the primary products from 18:3 omega-3 were 20:5 omega-3, 22:5 omega-3, and 22:6 omega-3. The majority of the long-chain fatty acids formed by astrocyte cultures, particularly 20:4 omega-6 and 22:6 omega-3, was released into the extracellular fluid. Although incapable of producing 20:4 omega-6 and 22:6 omega-3 from precursor fatty acids, neuronal cultures readily took up these fatty acids from the medium. These findings suggest that astrocytes play an important supportive role in the brain by elongating and desaturating omega-6 and omega-3 essential fatty acid precursors to 20:4 omega-6 and 22:6 omega-3, then releasing the long-chain polyunsaturated fatty acids for uptake by neurons.     

PI3K–Akt signaling controls PFKFB3 expression during human T-lymphocyte activation

It is commonly accepted that brain phospholipids are highly enriched with long-chain polyunsaturated fatty acids (PUFAs). However, the evidence for this remains unclear. We used HPLC–MS to analyze the content and composition of phospholipids in rat brain and compared it to the heart, kidney, and liver. Phospholipids typically contain one PUFA, such as 18:2, 20:4, or 22:6, and one saturated fatty acid, such as 16:0 or 18:0. However, we found that brain phospholipids containing monounsaturated fatty acids in the place of PUFAs are highly elevated compared to phospholipids in the heart, kidney, and liver. The relative content of phospholipid containing PUFAs is ~ 60% in the brain, whereas it is over 90% in other tissues. The most abundant species of phosphatidylcholine (PC) is PC(16:0/18:1) in the brain, whereas PC(18:0/20:4) and PC(16:0/20:4) are predominated in other tissues. Moreover, several major species of plasmanyl and plasmenyl phosphatidylethanolamine are found to contain monounsaturated fatty acid in the brain only. Overall, our data clearly show that brain phospholipids are the least enriched with PUFAs of the four major organs, challenging the common belief that the brain is highly enriched with PUFAs.     

Lipid analysis of immature pig oocytes

The detailed analysis of the lipid composition of immature pig oocytes represents the first such study carried out on mammalian eggs. In order to undertake a large scale lipid analysis using conventional extraction and chromatographic techniques a procedure for mass harvesting relatively large numbers of pig oocytes (200-300 oocytes/ovary) was developed. The study revealed that triacylglycerol was the major lipid component (100.71 nmol/mg protein) followed by cholesterol (32.71 nmol/mg protein). Phosphatidylcholine constituted the major phospholipid component (27.83 nmol/mg protein). Pig oocytes contained relatively low proportions of phosphatidylethanolamine (16.41% total phospholipid) and relatively high proportions of lysophosphatidylcholine (4.68% total phospholipid). The free fatty acid pattern was strikingly similar to the fatty acid composition of phosphatidylcholine. This observation, in conjunction with the observed high levels of lysophosphatidylcholine and the low ratio of phosphatidylethanolamine to phosphatidylcholine, suggests a fast rate of phospholipid turnover in the immature pig oocyte. Analysis of fatty acids esterified to the individual phospholipids and neutral lipids has shown that in all the classes examined, particularly in the neutral lipid fractions, there are high levels of the saturated fatty acid palmitic acid (16:0) and the monounsaturated fatty acid oleic acid (18:1). Triacylglycerol, free fatty acids and most of the phospholipids, particularly phosphatidylethanolamine, are considerably enriched in n-6 polyunsaturated fatty acids, specifically linoleic (18:2), arachidonic (20:4) and adrenic (22:4) acids. This may indicate an ability of oocytes to synthesize prostaglandins and leukotrienes. The results show that the lipid environment of the immature pig oocyte may be adapted to the highly specialized requirements of the cell, promoting growth and development with a potential role in the regulation of maturation.     

Peculiarities of the phospholipid and fatty acid composition of erythrocyte plasma membranes of the Black Sea fish

The phospholipid and the fatty acid composition of the main phospholipids families of erythrocyte plasma membranes was studied in two species of cartilaginous fish: the common thrasher (Raja clavata L.) and the common stingray (Dasyatis pastinaca) and three bony fish species: the scorpion fish (Scorpaena porcus L.), the smarida (Spicara flexuosa Raf.), and the horse mackerel (Trachurus mediterraneus ponticus Aleev). It was shown that in the studied fish, 70.0-80.0 % of all membrane phospholipids were composed of phosphatidylcholine and phosphatidylethanolamine. Phosphatidylserine, monophosphoinositide, and sphingomyelin were minor components whose content in the erythrocyte membrane fluctuated from 3.0 % to 13.0 %. The fatty acid phospholipids composition was represented by a large specter of acids. From saturated acids, basic for plasma membranes are palmitic (C16: 0) and stearic (C18: 0) acids. From unsaturated acids, the larger part belong to mono-, tetra-, penta-, and hexaenoic acids in fish phospholipids. The calculation of the double bond index and of the unsaturation coefficient showed difference in the deformation ability of erythrocyte membranes of the studied fish.     

Dietary effects on brain fatty acid composition: the reversibility of n-3 fatty acid deficiency and turnover of docosahexaenoic acid in the brain, erythrocytes, and plasma of rhesus monkeys

Rhesus monkeys given pre- and postnatal diets deficient in n-3 essential fatty acids develop low levels of docosahexaenoic acid (22:6 n-3, DHA) in the cerebral cortex and retina and impaired visual function. This highly polyunsaturated fatty acid is an important component of retinal photoreceptors and brain synaptic membranes. To study the turnover of polyunsaturated fatty acids in the brain and the reversibility of n-3 fatty acid deficiency, we fed five deficient juvenile rhesus monkeys a fish oil diet rich in DHA and other n-3 fatty acids for up to 129 weeks. The results of serial biopsy samples of the cerebral cortex indicated that the changes of brain fatty acid composition began as early as 1 week after fish oil feeding and stabilized at 12 weeks. The DHA content of the phosphatidylethanolamine of the frontal cortex increased progressively from 3.9 +/- 1.2 to 28.4 +/- 1.7 percent of total fatty acids. The n-6 fatty acid, 22:5, abnormally high in the cerebral cortex of n-3 deficient monkeys, decreased reciprocally from 16.2 +/- 3.1 to 1.6 +/- 0.4%. The half-life (t 1/2) of DHA in brain phosphatidylethanolamine was estimated to be 21 days. The fatty acids of other phospholipids in the brain (phosphatidylcholine, -serine, and -inositol) showed similar changes. The DHA content of plasma and erythrocyte phospholipids also increased greatly, with estimated half-lives of 29 and 21 days, respectively. We conclude that monkey cerebral cortex with an abnormal fatty acid composition produced by dietary n-3 fatty acid deficiency has a remarkable capacity to change its fatty acid content after dietary fish oil, both to increase 22:6 n-3 and to decrease 22:5 n-6 fatty acids. The biochemical evidence of n-3 fatty acid deficiency was completely corrected. These data imply a greater lability of the fatty acids of the phospholipids of the cerebral cortex than has been hitherto appreciated.     

Fatty acid exchange of phospholipids in membranes of rat heart

Incorporation of ¹⁴C fatty acids in phospholipids of plasma membranes and sarcoplasmic reticulum of rat heart was studied. Mainly phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were labelled. Our studies showed that the incorporation of unsaturated fatty acids (oleic and linoleic acid) was higher than for saturated fatty acids (palmitic and stearic acid). The range of uptake was between 0.2 and 2.2 nmol·mg⁻¹ protein·h⁻¹ and 0.5–7.4 nmol·μgatom⁻¹ P₁·h⁻¹, respectively. Uptake of activity in individual phospholipids (measured after separation on TLC) was calculated as percentage of total activity. Incorporation in phosphatidylcholine was higher than in phosphatidylethanolamine. Phosphatidylcholine showed an increasing sequence for the following fatty acids: C_18:0 < C_16:0 < C_18:0 < C_18:2. However, phosphatidylethanolamine showed a decreasing sequence for the incorporation of the same fatty acids. Labelling of PC was always greater than for PE, except for stearic acid which was better incorporated into phosphatidylethanolamine. Uptake of the same fatty acid into phospholipids of sarcoplasmic reticulum was always higher than uptake into plasma membranes. As incorporation of fatty acids bound to albumin was studied in isolated membranes of rat heart, the addition of ATP and CoASH was an absolute requirement.     

Changing Fatty Acid Content of Growth Cone Lipids Prior to Synaptogenesis

The developing mouse was used to assess biochemical changes in membrane lipids during the period when nerve growth cones become synapses. Growth cone particles and synaptosomes were simultaneously obtained from common brain homogenates. Incorporation of the essential fatty acid, docosahexaenoic acid (22:6 omega-3), was correlated with the developmental changes in endogenous fatty acid content of growth cones and synaptosomes. Analysis of endogenous lipid content indicated that, at all ages studied, the growth cones contained more arachidonoyl acyl chains (20:4 omega-6) than did synaptosomes. Before the onset of synaptogenesis, levels of arachidonoyl chains increased and levels of 22:6, oleoyl and linoleoyl chains decreased in synaptosomes. Although stearoyl and palmitoyl (16:0) remained stable in synaptosomes, 16:0 decreased in growth cones. With the exception of 16:0 and 20:4, endogenous fatty acyl content of growth cones and synaptosomes became similar by postnatal day 10, which coincides with the onset of synaptogenesis. When 5-day-old mouse pups were injected intraperitoneally with [3H]22:6, the incorporation into growth cone and synaptosome phospholipids was greatest in phosphatidylethanolamine, followed by phosphatidylserine and phosphatidylcholine. Nominal labeling was present in phosphatidic acid and phosphatidylinositol. Labeling in neutral lipids was less than that of phospholipids, with triacylglycerol incorporating most of the neutral lipid label, followed by diacylglycerol and free 22:6. Only the growth cone fraction contained detectable amounts of 22:6-labeled cholesterol esters. The distribution of 22:6 label in plasma 72 h after injection indicated that approximately 60% of the label was in phospholipids with approximately 40% in neutral lipids and less than 5% in free fatty acids.(ABSTRACT TRUNCATED AT 250 WORDS)