Chlorohydrin formation from unsaturated fatty acids reacted with hypochlorous acid.

Stimulated neutrophils produce hypochlorous acid (HOCl) via the myeloperoxidase-catalyzed reaction of hydrogen peroxide with chloride. The reactions of HOCl with oleic, linoleic, and arachidonic acids both as free fatty acids or bound in phosphatidylcholine have been studied. The products were identified by gas chromatography-mass spectrometry of the methylated and trimethylsilylated derivatives. Oleic acid was converted to the two 9,10-chlorohydrin isomers in near stoichiometric yield. Linoleic acid, at low HOCl:fatty acid ratios, yielded predominantly a mixture of the four possible monochlorohydrin isomers. Bischlorohydrins were also formed, in increasing amounts at higher HOCl concentrations. Arachidonic acid gave a complex mixture of mono- and bischlorohydrins, the relative proportions depending on the amount of HOCl added. Linoleic acid appears to be slightly more reactive than oleic acid with HOCl. Reactions of oleic and linoleic acids with myeloperoxidase, hydrogen peroxide, and chloride gave chlorohydrin products identical to those with HOCl. Lipid chlorohydrins have received little attention as products of reactions of neutrophil oxidants. They are more polar than the parent fatty acids, and if formed in cell membranes could cause disruption to membrane structure. Since cellular targets for HOCl appear to be membrane constituents, chlorohydrin formation from unsaturated lipids could be significant in neutrophil-mediated cytotoxicity.     

Fatty acid chlorohydrins and bromohydrins are cytotoxic to human endothelial cells

Reaction of unsaturated lipids with the hypohalous acids (hypochlorous acid and hypobromous acid) results in the addition of the halide (X) across double bonds to form halohydrins (-CH2CH(OH)CH(X)CH2-). These modified lipids could be potentially destabilising to cell membranes due to their increased polarity. We have investigated the effect of pre-formed halohydrins on human umbilical vein endothelial cells (HUVEC) by incubating cultured cells with oleic acid micelles containing chlorohydrins or bromohydrins. Cell detachment and necrotic death were observed with increasing doses of halohydrins, whereas the cells were unaffected by equivalent doses of oleic acid. Bromohydrins caused more lysis than did chlorohydrins at equivalent doses. Complete lysis was seen with 200 microM fatty acid/chlorohydrin micelles and with 50 microM fatty acid/bromohydrin micelles. Chlorohydrin uptake was much less than the oleic acid control whereas bromohydrins were incorporated into the endothelial cells similarly to oleic acid. This difference or the bulkier nature of the bromohydrins could account for their increased toxicity. This study has demonstrated the potential toxicity of the halohydrins, and implications for their formation in inflammation are discussed.     

Dietary n-9, n-6, and n-3 fatty acids modify linoleic acid more than arachidonic acid levels in plasma and platelet lipids and minimally affect platelet thromboxane formation in the rabbit

We have studied the effects of semisynthetic diets containing 5% by weight (12% of the energy) of either olive oil (70% oleic acid, OA) or corn oil (58% linoleic acid), or fish oil (Max EPA, containing about 30% eicosapentaenoic, EPA C 20:5 n-3, plus docosahexaenoic, DHA C 22:6 n-3, acids, and less than 2% linoleic acid), fed to male rabbits for a period of five weeks, on plasma and platelet fatty acids and platelet thromboxane formation. Aim of the study was to quantitate the absolute changes of n-6 and n-3 fatty acid levels in plasma and platelet lipid pools after dietary manipulations and to correlate the effects on eicosanoid-precursor fatty acids with those on platelet thromboxane formation. The major differences were found when comparing the group fed fish oil and depleted linoleic acid vs the other groups. The accumulation of n-3 fatty acids in various lipid classes was associated with modifications in the distribution of linoleic acid and arachidonic acid in different lipid pools. In platelets maximal incorporation of n-3 fatty acids occurred in phosphatidyl ethanolamine, which also participated in most of the total arachidonic acid reduction occurring in platelets, and linoleic acid, more than archidonic acid, was replaced by n-3 fatty acids in various phospholipids. The archidonic acid content of phosphatidyl choline was unaffected and that of phosphatidyl inositol only marginally reduced. Thromboxane formation by thrombin stimulated platelets did not differ among the three groups, and this may be related to the minimal changes of arachidonic acid in phosphatidyl choline and phosphatidyl inositol.     

The influence of ionic detergents on the phospholipid fatty acid compositions of Porphyridium purpureum

The phospholipid fatty acid composition of Porphyridium purpureum on a solid medium was studied in the presence of sodium dodecyl sulphate (SDS) and cetyl trimethylammonium bromide (CTAB). The most common fatty acids in phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) were palmitic (16:0), stearic (18: 0), linoleic (18:2ω 6), arachidonic (20:4ω 6) and eicosapentaenoic (20:5ω 3) acids, 20:4ω 6 being very abundant. In phosphatidyl glycerol (PG) the most common acids were 16:0, trans-hexadecenoic acid (tr 16:1ω 13), oleic acid (18:1) and 20:4ω 6. Both detergents increased the saturation grade of PC and PE by decreasing the relative amount of the polyunsaturated acids, especially 20:4ω 6. A corresponding increase in the amounts of saturated acids was observed in PC and PE. The changes in PG fatty acid composition were not very significant: a slight increase was observed in the amounts of 16:0 and tr 16:1ω 13 , with a corresponding decrease in the amounts of 20:4ω 6 and 20:5ω 3. Both detergents decreased the PC/PE and the (PC + PE)/PG ratios very markedly, most probably as a result of increases in the amounts of PE and PG. In the presence of CTAB the cells seemed to contain much more phospholipids than in the presence of SDS, perhaps as a result of the mucilage-precipitating effect of CTAB. The significance of the findings is discussed.     

Die Lipide von Endomycopsis vernalis bei verschiedener Stickstoff-Ernährung

1. Endomycopsis vernalis was cultivated on media with different N supply: series A 1%, series B 0,125% asparagine. Sonified cells were extracted and yielded 14.3% (A) and 65.3 (B) total lipids/non lipid dry matter respectively.
2. Neutral and complex lipids were separated by rubber membrane dialysis. There is no difference in the percentage of complex lipids of both series. The increase of lipids in cells grown on low N level is due to a higher content of neutral lipids.
3. Components of the neutral lipids, analysed by DC, were diglycerides, triglycerides, free and esterified ergosterol. Their percentage is influenced by the nutritional conditions. There is a significant increase of triglycerides and of sterol esters in the high lipid cells of series B.
4. Methyl esters of component fatty acids of glycerides and sterol esters were analyzed by GLC. Saturated acids C₁₄, C₁₅, C₁₆, C₁₇, C₁₈, monoenic acids C₁₆ and C₁₈, linoleic and linolenic acids were found to be present. Major acids were in all cases 18:1 (17–57%), 18:2 (18–50%) and 16:0 (10–18%). Linolenic acid is higher in di-and triglycerides of low lipid cells of series A than in high lipid cells of series B. Both qualitative and quantitative differences of fatty acids were found in sterol esters of series A and B respectively.
5. The major components of complex lipids, identified by DC and isolated by CC, in both series, were phosphatidyl choline (A:36.5, B:41.0%) and phosphatidyl ethanolamine (A:24.9, B:20.5%) in addition to small amounts of lysophosphatidyl choline, lysophosphatidyl ethanolamine, phosphatidyl serine, monophosphoinositide, diphosphatidyl glycerol and, possibly cerebroside like substances.
6. Methyl esters of the fatty acids of phosphatidyl choline and ethanolamine from both series were determined by GLC. In all samples 16:0, 18:0, 18:1, 18:2 and 18:3 acids were present besides of traces of 16:1 and 17:0. In contrast to neutral lipids the major acid of phospholipids is linoleic (53–58%), followed by oleic (8–24%) and linolenic acid (1–18%). The percentages of palmitic (4–8%) and stearic acids (tr.-1%) are small. Low lipid cells of series A differ from high lipid cells of series B by an increase of linolenic, and a decrease of linoleic acids, both in phosphatidyl choline and phosphatidyl ethanolamine.

     

Lipid and sterol composition of the pollen of the west african oilpalm, Elaeis guineensis

The lipid classes, fatty acid methyl esters and the sterols of oilpalm pollen were analysed. The neutral lipid fraction consisted of triglycerides, esterified and free sterols and trace amounts of hydrocarbons. Monogalactosyl and digalactosyl diglycerides, phosphatidyl choline, phosphatidyl inositol and phosphatidyl ethanolamine represented the polar lipids. The major fatty acids were linoleic, palmitic and linolenic acids together with small to trace amounts of oleic, stearic, arachidic, myristic, lauric, palmitoleic and margaric acids. Unsaturated fatty acids predominated over saturated ones in the ratio of 3:2. The 4-desmethyl sterols were the major phytosterols in the free form but they constituted a lower proportion of the sterols in the esterified state. 28-Isofucosterol was isolated and characterized as the principal sterol.     

Lipids and fatty acids of the southwestern corn borer,Diatraea grandiosella

The lipids of the adults and of several immature stages of the southwestern corn borer, Diatraea grandiosella, were studied after they were fed natural corn stalks or artificial diets. Linoleic acid (18:2) was the major fatty acid of the neutral lipids in both the natural and the artificial diets, but aleic acid (18:1) was the principal neutral lipid in all insect stages. Also, linoleic acid and oleic acid were the principal acids in the insect phospholipids of all stages. The content of linoleic acid in the natural diet was also high, but that in the artificial diet appeared to be much too low for insect requirements. Phosphatidyl choline (PC) and phosphatidyl ethanolamine (PE) were the major phospholipids in all growth stages. Thus, in larvae diapausing in the field, the unsaturated fatty acid content of PC was 59·3 per cent, primarily 16:1 and 18:1, and PE was 87·4 per cent, primarily 18:1, 18:2, and 18:3, and the fatty acids in the number 1- and 2-positions of PC were 53·6 and 97·2 per cent unsaturated, respectively. The haemolymph of diapausing southwestern corn borer larvae contained primarily glycerides but also had some PC and PE. Fat body from diapausing larvae contained primarily 16:0, 16:1, and 18:1 in a ratio of 1 : 1 : 2. Thus lipids of the southwestern corn borer do not reflect dietary lipids as closely as do other insects studied.     

Multivariate approach to evaluating the fatty acid composition of seed oil in a doubled haploid population of winter oilseed rape (Brassica napus L.)

The fatty acid composition of oil of the zero erucic acid commercial Brassica napus L. is typical for this species. It is rich in oleic acid and contains moderate levels of linoleic and linolenic acid. For human nutrition, it is advantageous primarily to obtain the highest possible content of oleic acid and to maintain the 2:1 ratio of linoleic to linolenic acid, while preserving the average total content of saturated acids. Uni- and multivariate analyses of variance were used for evaluation of doubled haploid lines of winter oilseed rape in respect of five fatty acids: palmitic (C16:0), stearic (C18:0) oleic (C18:1), linoleic (C18:2) and linolenic (C18:3). Some proposals of studying doubled haploid (DH) lines with the use of canonical transformation were also given. In MANOVA, the five original variables (individual fatty acids) were replaced by three 'new' variables (combinations of these acids) and used to evaluate DH lines with respect to the requirements concerning the nutritional role of fatty acids. The first variable was the total content of the saturated acids (C16:0 + C18:0), the second (unchanging) was the content of the monounsaturated acid C18:1, and the third was the difference between polyunsaturated acids, i.e. between linoleic acid, and the doubled content of linolenic acid (C18:2 - 2 x C18:3).     

Effect of long-chain fatty acids on the binding of thyroxine and triiodothyronine to human thyroxine-binding globulin

The effect of long-chain fatty acids on the binding of thyroxine to highly purified human thyroxine-binding globulin has been studied by equilibrium dialysis performed at pH 7.4 and 37 degrees C. At a fixed molar ratio of 2000:1 of fatty acid to thyroxine-binding globulin, the degree of binding inhibition based on the percent change in nK value relative to the control as determined from Scatchard plots was: palmitic, 0%; stearic, 0%; oleic, 76%; linoleic, 69%; and linolenic, 61%. At a 500:1 molar ratio of oleic acid to thyroxine-binding globulin, equivalent to 0.125 mM free fatty acid in serum, thyroxine binding was inhibited by 18%, increasing to 93% at a 4500:1 molar ratio. At molar ratios of oleic acid to thyroxine-binding globulin of 1000:1, 2000:1 and 4000:1, the degree of inhibition of triiodothyronine binding was 24%, 41% and 76%, respectively. The results indicate that the unsaturated long-chain fatty acids are potent inhibitors of thyroxine binding to thyroxine-binding globulin, whereas the saturated fatty acids have little or no effect on thyroxine binding.     

次氯酸与不饱和脂肪酸氧化机制和转化产物的理论研究

摘要 目的：揭示次氯酸与不饱和脂肪酸的氧化反应机制及转化产物。方法：运用Gaussian 16软件包,采用密度泛函方法M06-2X(D3),结合6-31+G(d)基组,在SMD液相水模型水平下进行计算。结果：次氯酸与单不饱和脂肪酸油酸的氧化反应是先形成氯鎓离子中间体,氯鎓离子再与水分子反应生成氯醇,第一步氯鎓离子的形成是控速步骤,其反应活化自由能~8 kcal/mol。环氧化合物和短链的醛是两种转化产物,前者由氯醇脱氯化氢而来,而后者由环氧化合物和氯醇通过系列与次氯酸根的反应而得到,生成它们的控速步骤的反应活化自由能分别为23 和24 kcal/mol。选取两个乙基为取代基的乙烯为油酸模型,其与次氯酸反应的活化自由能仅比油酸高1 kcal/mol。计算得到次氯酸与亚油酸、顺-9,反-11 亚油酸、梓树酸和花生四烯酸模型氧化反应生成氯醇的活化自由能分别是~10、13、16和14 kcal/mol。结论：氯鎓离子中间体机制是次氯酸与不饱和脂肪酸氧化反应的主要机制,反应的活化自由能通常低于15 kcal/mol,意味着此氧化反应动力学上容易发生。氧化产物氯醇能转化为环氧化合物和短链的醛,但活化自由能较高,约23和24 kcal/mol。选取距离双键3个碳以内的结构为不饱和脂肪酸模型,它能够很好地反映不饱和脂肪酸的反应活性。     

Phosphatidyl choline interaction with bovine serum albumin: effect of the physical state of the lipid on protein-lipid complex formation.

Radioactively labeled [¹⁴C]phosphatidyl choline dispersed on Celite was equilibrated with bovine serum albumin solutions buffered at pH 8.0. Phosphatidyl choline was rapidly solubilized in the presence of serum albumin, and formed stable protein-lipid complexes which were isolated by gel-filtration through a Sepharose 4B column. Under similar conditions, equilibration of the protein with phosphatidyl choline liposome dispersions in buffer did not result in complex formation. The altered physical state of phosphatidyl choline on the weakly adsorbing Celite surface appears to be essential for binding by native bovine serum albumin. This work reports the first observation of phosphatidyl choline binding to native serum albumin in bulk phase and suggests the possibility of exposing monodisperse lipids, under controlled conditions, to proteins having lipid binding properties.     

Changes in the composition of membrane lipids in relation to differentiation in Aegle marmelos callus cultures

Changes in fatty acid, phospholipid and galactolipid contents during cellular and organ differentiation in Aegle marmelos have been described. Decrease in phosphatidylinositol content and presence of 3-trans-hexadecenoic acid in phosphatidylglycerol were related to greening and shoot buds differentiation. The galactolipids level, the monogalactosyl diglyceride/digalactosyl diglyceride ratio and the linolenic acid level (mainly in monogalactosyl diglyceride) increased with the degree of differentiation, indicating the possible biogenesis of functional chloroplasts.Abbreviations 2,4-D 2,4 dichlorophenoxyacetic acid - BA benzylaminopurine - DW dry weight - FW fresh weight - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PG phosphatidylglycerol - PS phosphatidyl serine - MGDG monogalactosyl diglyceride - DGDG digalactosyl diglyceride - 16:0 palmatic acid - 18:0 stearic acid - 18:1 oleic acid - 18:2 linoleic acid - 18:3 linolenic acid - trans-16:1 3-trans-hexadecenoic acid     

The utilisation of yolk phosphoglycerides by the alligator during embryonic development

Summary A study was made of the concentrations and fatty acid compositions of the major phosphoglycerides in the yolk of the alligator egg on the 8th and 75th days of incubation. The major phosphoglycerides were phosphatidyl choline and phosphatidyl ethanolamine which at the start of incubation accounted for 72 and 18%, respectively, of total phosphoglyceride. Phosphoglycerides were characterised by low levels of linoleic acid but extremely high levels of C20 and C22 polyunsaturates. The extensive absorption of phosphoglyceride over the incubation period was accompanied by a reduction in percentage of phosphoglyceride within the residual yolk lipid, a reduction in the proportion of phosphatidyl choline within the total phosphoglyceride, and increases in the proportions of phosphatidyl ethanolamine and lyso-phosphatidyl choline. There were small but wide-spread changes in the fatty acid composition of the phosphatidyl choline during incubation. Within the phosphatidyl ethanolamine and phosphatidyl serine fractions there were very large reductions in the C20 and C22 polyunsaturated fatty acid levels. The phosphoglyceride changes are discussed with respect to the unique role of yolk lipid absorption in the nutrition of the developing embryo.     

The Binding of Luxol Fast Blue Arn by Various Biological Lipids

A determination of the selectivity and approximate stoichiometry of Luxol Fast Blue ARN by known chemical compounds showed that phosphatidyl ethanolamine, phosphatidyl serine, and phosphatidyl inositol bound the dye with an apparently stoichiometric ratio of 1 dye molecule to 2 molecules of lipid. Phosphatidyl choline, sphingomyelin, and palmitic acid showed a much weaker reaction. Of these, phosphatidyl choline bound the least amount of dye; about 1 dye molecule per 13-20 lipid molecules. Glycerides, methyl and cholesteryl esters of fatty acids, cholesterol, cerebrosides, and oleic acid gave negative results, as did a variety of low molecular weight substances, including ethanolamine, choline, inositol, and serine. Such negative results indicate that no isopropanol-insoluble complexes were formed with the dye. The behavior of the dye toward several phospholipids suggests that the phosphate groups are essential to the binding reaction and that the quaternary amine of phosphatidyl choline may interfere with it. The selectivity of the dye-binding reaction and the properties of the dye-phospholipid complexes suggest that this reaction will be useful for cytochemical studies of phospholipids, particularly those of the cell membrane     

Essential fatty acid uptake and esterification in primary culture of rat hepatocytes

Primary cultures of adult rat hepatocytes were used to compare the uptake and esterification of essential polyunsaturated fatty acids (18:2, 20:3 and 20:4 of the n-6 series) with those of palmitic and oleic acids. The uptake of unesterified fatty acids was linearly related to the free fatty acid/albumin molar ratio for 14 h and did not depend on the unbound free fatty acid level. Whatever the initial free fatty acid/albumin molar ratio, it dropped to 0.5 +/- 0.1 mM after 14 h, thus showing that hepatocytes have a high capacity for clearing free fatty acids from the medium at high free fatty acid/albumin molar ratios. The free fatty acid uptake become saturable when the free fatty acid and albumin concentrations were raised and the free fatty acid/albumin ratio remained constant. This strongly suggests that albumin-hepatocyte interaction mediates free fatty acid uptake. This uptake was identical whatever the fatty acid tested and did not depend on the relative amounts of fatty acids when they were added simultaneously. Triacylglycerol accumulation and synthesis, monitored by labelled fatty acids, were related to the free fatty acid/albumin molar ratio and exhibited no specificity for the series of fatty acids tested. Triacylglycerols were enriched in all the fatty acids tested by up to 60%, and fatty acid incorporation into diacylglycerols and triacylglycerols reflected the free fatty acid composition of the medium. By contrast, neither the level nor the synthesis of phospholipids varied with free fatty acid/albumin, but the rate of phospholipid turnover depended on the fatty acids tested. Accumulation of these acids was smaller in phospholipids than in triacylglycerols. When linoleic and arachidonic acids were added together, phospholipids (especially phosphatidylethanolamine and phosphatidylinositol) were more enriched in arachidonic acid than triacylglycerols. This might be due to the specificity for fatty acid of the enzymes involved in phospholipid metabolism.     

Control of the potassium ion-stimulated adenosine triphosphatase of pig gastric microsomes: effects of lipid environment and the endogenous activator

The K⁺-stimulated ATPase activity associated with the purified gastric microsomes from the pig gastric mucosa can be completely inactivated by treatment with 15% ethanol for 60 s at 37 °C but not at 25 °C. Sequential exposure of the microsomes to 15% ethanol at 25 and 37 °C caused the release of 2.9 and 4.3% of the total membrane phospholipids, respectively, consisting entirely of phosphatidyl choline and phosphatidyl ethanolamine. The ethanol-treated (37 °C) membrane had high basal (with Mg²⁺ as the only cation in the assay mixture) activity, which was further enhanced during reconstitution with phosphatidyl choline or phosphatidyl ethanolamine. The high basal activities could be reduced to the normal control level by assaying the enzyme in presence of the “activator protein,” partially purified from the soluble supernatant of the pig gastric cells. Phosphatidyl choline was somewhat more effective than phosphatidyl ethanolamine in the restoration of the activity of the ethanol-treated enzyme while phosphatidyl serine, phosphatidyl inositol, and sphingomyelin were without any effect. Synthetic phosphatidyl choline with various fatty acid substitutions were tested for their effectiveness in the restoration of the ethanol-inactivated enzyme. The distearoyl (18:0), dioleoyl (18:1), and dilinoleoyl (18:2) derivatives of phosphatidyl choline were almost equally effective while dipalmitoyl (16:0) phosphatidyl choline was somewhat less effective in the reconstitution process. Cholesterol appeared to interfere with phosphatidyl choline in the restoration of the activity of ethanol-treated enzyme. The fatty acid composition of phosphatidyl choline and phosphatidyl ethanolamine extracted by 15% ethanol at 37 °C was clearly different than those of the total microsome. Our data suggest that the phospholipids extracted by 15% ethanol at 37 °C are derived primarily from the immediate lipid environment of the enzyme and ATP together with Mg²⁺ and K⁺ help the partially delipidated enzyme to retain the appropriate conformation for the subsequent reconstitution. Furthermore, ethanol appears to either release or inactivate the membrane-associated activator protein, demonstrated to be essential for the K⁺-stimulated activity of the pig gastric ATPase.     

Interaction between oleic acid-containing pH-sensitive and plain liposomes. Fluorescent spectroscopy studies.

The energy transfer method has been applied to study the interaction between pH-sensitive liposomes (phosphatidyl ethanolamine/oleic acid/cholesterol, 4:2:4 molar ratio) and plain liposomes (phosphatidyl choline/phosphatidyl ethanolamine/cholesterol, 4:2:3 molar ratio). It was shown that a slow fusion process occurs between two types of liposomes. Also, the transfer of oleic acid from pH-sensitive liposomes to plain liposomes takes place. This transfer results in the increased permeability of both pH-sensitive and plain liposomes, facilitating the release of liposome-entrapped fluorescent dye. The data obtained were used for a possible explanation of the mechanism of intracytoplasmic drug delivery by pH-sensitive oleic acid-containing liposomes.     

Characterization of gastric mucosal membranes: lipid composition of purified gastric microsomes from pig, rabbit, and frog

The lipid compositions of the gradient-purified gastric microsomal membranes from the fundic mucosa of pig, rabbit, and frog were determined. The total lipid content varied widely. Compared to the rabbit (21.6 ± 0.6 mg/100 mg protein), the pig had about twice as much and the frog about three times as much lipid. The levels of cholesterol were higher in both mammalian species (about 32% of the lipid) compared to frog (23%). Phospholipids accounted for about 45, 54, and 52% of the total microsomal lipids from pig, rabbit, and frog and the molar ratios of cholesterol to phospholipid in the three species were 1.95, 1.6, and 1.17, respectively. Phosphatidyl choline and phosphatidyl ethanolamine together constituted about 75% of the total phospholipids in pig and frog and 93% in rabbit gastric microsomes. Sphingomyelin comprised 19.3, 3.2, and 1.5% in pig, rabbit, and frog, respectively. Phosphatidyl inositol constituted 5, 2.7, and 23.6% in pig, rabbit, and frog, respectively. The ratios of phosphatidyl ethanolamine to phosphatidyl choline were 1.17, 1.1, and 0.85 in pig, rabbit, and frog, respectively. The saturated fatty acids 16:0 and 18:0 and the unsaturated fatty acid 18:1 and 18:2 were the predominant fatty acids in all phospholipids. The ratios of saturated to unsaturated fatty acids were between 0.8 and 0.9 in phosphatidyl choline and 0.27 and 0.5 in phosphatidyl ethanolamine from all three species. The contributions by saturated fatty acids were much more in phosphatidyl inositol and sphingomyelin than in phosphatidyl choline and phosphatidyl ethanolamine from all species. Position 1 of phosphatidyl choline had 63% saturated and 37% unsaturated fatty acids; while the reverse was true for position 2. Phosphatidyl ethanolamine, however, had 85% saturated fatty acids in position 1 compared to only 25% in position 2. Arachidonic acid (20:4) was present in significant amounts in all species located exclusively at position 2 of both phosphatidyl choline and phosphatidyl ethanolamine.     

Dose-effect of dietary oleic acid: oleic acid is conditionally essential for some organs

The minimum dietary intake of oleic acid that is indispensable to maintain a normal content of this fatty acid in several tissues (heart, muscle, kidney and testis) was determined in the rat. For this purpose, a dose-effect study was conducted using an experimental protocol with 7 groups of rats who received a diet in which the oleic acid level varied from 0 to 6000 mg per 100 g diet, but the other ingredients were identical (in particular the essential fatty acids, linoleic and alpha-linolenic acid). Female rats were fed the diets from two weeks before mating, and their pups were killed aged either 21 or 60 days. When the level of oleic acid in the diet was increased, the main modifications observed in 21-day-old deficient pups were as follows: (i) for 18:1n-9, in the liver, muscle, heart, kidney, and testis, a plateau was reached at about 4 g oleic acid per 100 g diet. Below this level, the higher the dose the greater the response; (ii) for 16:1n-7, the concentration decreased in the liver, muscle, heart, kidney and testis; (iii) the concentration of 18:1n-7 decreased in the kidney, muscle, and testis; (iv) some minor modifications were noted for the other fatty acids. In mother's milk at 14 days of lactation, when dietary oleic acid increased, the levels of 18:1(n-9) also increased; the increase was regular and did not reach a plateau. In 60-day-old rats, the results were generally similar to those in 21-day-old rats, but with some differences, in particular a slight decrease in oleic acid concentration in the liver and kidney at the highest dietary oleic acid level.     

Interaction of rat liver microsomes containing saturated or unsaturated fatty acids with fatty acid binding protein: Peroxidation effect

In the studies described here rat liver microsomes containing labeled palmitic, stearic, oleic or linoleic acids were incubated with fatty acid binding protein (FABP) and the rate of removal of¹⁴C-labeled fatty acids from the membrane by the soluble protein was measured using a model system. More unsaturated than saturated fatty acids were removed from native liver microsomes incubated with similar amounts of FABP. Thein vitro peroxidation of microsomal membranes mediated by ascorbate-Fe⁺⁺, modified its fatty acid composition with a considerable decrease of the peroxidizability index. These changes in the microsomes facilitated the removal of oleic and linoeic acids by FABP, but the removal of palmitic and stearic acids was not modified. This effect is proposed to result from a perturbation of membrane structure following peroxidation with release of free fatty acids from susceptible domains.Abbreviations BSA bovine serum albumin - FABP fatty acid binding protein