Assessing palatability of long-chain fatty acids from the licking behavior of BALB/c mice

Dietary oils such as corn oil, olive oil, and canola oil, which primarily contain triacylglycerol and small quantities of fatty acids, are highly palatable to animals. In a previous study, we examined the short-term (60 s) licking behavior of mice and observed that they exhibited a high licking response to a low concentration of fatty acid (linoleic acid), which is comparable to that observed for pure corn oil. This finding suggests that fatty acids contribute to the palatability of dietary oils. In order to supplement our knowledge of the fundamental features of fatty acid palatability in the oral cavity, we assessed the licking behavior of BALB/c mice to investigate the palatability of various types of long-chain fatty acids. The mice showed high licking responses to 1% unsaturated 16- and 18-carbon fatty acids (palmitoleic acid, 16:1; oleic acid, 18:1; linoleic acid, 18:2; and linolenic acid, 18:3), low licking responses to 16- and 20-carbon fatty acids (palmitic acid, 16:0 and arachidonic acid, 20:4), and no significant response to saturated fatty acids (stearic acid, 18:0 and arachidic acid, 20:0) or fatty acid derivatives (methyl linoleate and linole alcohol). Additionally, there were differences in the palatability of 18-carbon unsaturated fatty acids at very low concentrations. At fatty acid concentrations of 0.04% and 0.0625%, the mice showed significant preference for linoleic acid and linolenic acid, but not oleic acid, when compared with mineral oil. These results suggest that mice show high licking responses to 16- and 18-carbon unsaturated long-chain fatty acids at low concentrations. Further, we suggest that sensitivity to fatty acids is affected by the saturated state of the fatty acid, carbon chain length, and terminal carboxyl group.     

Carbon stripping extracts serum free fatty acids: implications for media supplementation of cultured type II pneumocytes

Carbon stripping is a process that is widely used to remove hormones from serum. Because addition of serum to culture media also provides exogenous fatty acids that influence lipid metabolism of cultured cells, we investigated the effects of carbon stripping on the composition of the phospholipid and free fatty acid fractions in fetal bovine serum and the effects of these changes on phosphatidylcholine synthesis by cultured adult alveolar type II cells. Carbon stripping resulted in quantitative and qualitative changes in serum free fatty acids. The process effectively extracted greater than or equal to 99% free fatty acids and, to a lesser extent, phospholipids. There were also qualitative changes in the relative composition of the remaining free fatty acids with a selective loss of oleic and linoleic free fatty acids. However, the relative composition of the serum phospholipid fatty acid fraction was unaffected. Type II cells isolated from adult male rat lung and cultured in Dulbecco's modified Eagle's medium supplemented with 10% carbon-stripped fetal bovine serum (FBS-CS) incorporated [3H]choline into phosphatidylcholine at a rate 36% less than the rate of control cells cultured with unstripped FBS. Addition of oleic acid to FBS-CS supplemented media increased total phosphatidylcholine synthesis by adult type II cells by 67-71%. In contrast, addition of palmitic acid inhibited PC synthesis 51-67%. The combination of oleic and palmitic acids resulted in a rate of [3H]choline incorporation into phosphatidylcholine similar to the rate for control cells cultured in FBS-CS-supplemented media alone. Although synthesis of disaturated phosphatidylcholine was unaffected by exogenous fatty acids, addition of fatty acids altered the proportion of disaturated phosphatidylcholine synthesis relative to total phosphatidylcholine synthesis. The presence or absence of the hormones, dexamethasone and triiodothyronine, did not explain the difference in rate of phospholipid synthesis by type II cells cultured in untreated versus carbon-stripped serum supplemented media. These results suggest that the removal of serum free fatty acids by carbon stripping can influence phospholipid metabolism of cultured type II cells. Because serum free fatty acids influence cellular lipid composition and potentially cell metabolic functions, carbon-stripped serum may not be the optimal choice for media supplementation of cultured cells.     

Plasma pattern of growth hormone regulates sexual differentiation of phosphatidylcholine in rat plasma

The effects of continuous and intermittent administration of human growth hormone (hGH) in the regulation of plasma phosphatidylcholine fatty acid composition was studied in adult hypophysectomized male and female Sprague-Dawley rats. Human GH was given for 7 days, either continuously by means of Alzet osmotic minipumps implanted s.c. or intermittently by means of s.c. injections at 12-h intervals. The 'masculinizing' effect of hypophysectomy on the fatty acid composition of plasma phosphatidylcholine in female rats, i.e. an increase in the proportions of palmitic and linoleic acids and a decrease in the proportions of stearic and arachidonic acids, was to a large extent reversed by continuous administration of hGH, while intermittent administration had no consistent effect. This effect of continuous hGH administration similar effect of continuous administration of hGH was also observed in hypophysectomized male rats. Prolactin had no effect on the fatty acid composition of phosphatidylcholine. Replacement therapy with thyroid hormones and glucocorticoids had a small effect on the proportions of palmitic and stearic acids in plasma phosphatidylcholine. It is concluded that the more continuous secretory pattern of GH in female rats is involved in the sexual differentiation of the fatty acid composition of plasma phosphatidylcholine.     

Cellular fatty acids of Alcaligenes and Pseudomonas species isolated from clinical specimens.

The cellular fatty acid composition of 25 clinical isolates of Alcaligenes and Pseudomonas was determined by gas-liquid chromatography (GLC). The GLC fatty acid profiles of three species of Pseudomonas were markedly different from those of Alcaligenes. The most significant differences were the presence and relative amounts of hydroxy, branched-chain, and cyclopropane fatty acids. One of the major fatty acids in A. faecalis was a 17-carbon cyclopropane (17 delta) acid, whereas a 15-carbon branched-chain acid (13-methyl tetradecanoate) characterized isolates of P. putrefaciens. The determination of these fatty acids by GLC provides a rapid and specific means of distinguishing clinical isolates of Pseudomonas and Alcaligenes.     

Cellular fatty acids of Capnocytophaga species.

The cellular fatty acid composition of 18 clinical isolates and 4 reference strains of Capnocytophaga species (Capnocytophaga ochracea, Capnocytophaga gingivalis, and Capnocytophaga sputigena) was determined by gas-liquid chromatography. The fatty acid profiles of the 22 cultures were essentially identical and were characterized by major amounts (60% or greater) of a saturated, iso-branched-chain, 15-carbon acid (13-methyl-tetradecanoate) and the presence of two relatively uncommon saturated, iso-branched, 3-hydroxy acids (13-methyl-3-hydroxy-tetradecanoate and 15-methyl-3-hydroxy-hexadecanoate). The presence and relative amounts of these acids distinguish Capnocytophaga spp. from other gliding bacteria.     

Identification of Achromobacter species by cellular fatty acids and by production of keto acids.

The cellular fatty acid composition and metabolic products of 12 reference strains of Achromobacter sp. and A. xylosoxidans were determined by gas-liquid chromatography (GLC). Results showed that the two Achromobacter groups are strikingly different and can be readily distinguished on the basis of cellular fatty acids and the short-chain acids produced by Achromobacter sp. The major cellular fatty acids of Achromobacter sp. were octadecenoic (18:1) and a 19-carbon cyclopropanoic (19:0 delta) acid, whereas hexadecanoic (16:0) and a 17-carbon cyclopropanoic (17:0 delta) acid were principal components of the lipids of A. xylosoxidans. Hydroxy acids were not found in strains of Achromobacter sp. but comprised approximately 20% of the cellular fatty acids of A. xylosoxidans. In addition, Achromobacter sp. produced relatively large amounts of 2-ketoisocaproic acid, which was detected in only trace amounts from strains of A. xylosoxidans. The data show that GLC tests provide additional criteria for differentiating groups which are very closely related when evaluated with conventional tests. The GLC tests can be readily adapted in the clinical laboratory because they are rapid, highly reproducible, relatively inexpensive, and simple to perform.     

Plasma lipoproteins and fatty acid composition during a moderate eicosapentaenoic acid diet

The effect of a diet rich in marine fatty acids, especially eicosapentaenoic acid, on plasma lipids (total plasma cholesterol, HDL cholesterol, total triglycerides and apolipoproteins A and B) and fatty acid composition in plasma phosphatidylcholine (PC) was studied in 10 healthy men. They were maintained for 11 weeks on their normal diet which was partly replaced by 150-200 g of fatty fish per day. In the same individuals this diet had previously caused a delay in primary haemostasis and a decrease in platelet aggregability similar to that caused by acetylsalicylic acid, a known inhibitor of thromboxane A2 formation. Apart from its effect on haemostasis, the fish diet substantially reduced serum triglycerides (by 43%, p less than 0.01) but caused no changes in total plasma or HDL cholesterol or apolipoproteins A and B. After three weeks on the diet the proportion of plasma PC omega-3 polyunsaturated fatty acids increased (C20:5 and C22:6) and omega-6 fatty acids decreased (C18:2 and C20:3). The relative plasma PC content of arachidonic acid was unaffected throughout. These alterations in plasma PC fatty acid composition were principally in accordance with those seen in platelet membrane PC. There was a linear correlation between the content of omega-3 and of omega-6 fatty acids in plasma PC with that of platelet PC as well as in predominate individual fatty acids of the two series. Six weeks after the volunteers had resumed their usual diet, total triglycerides and the fatty acid composition of plasma PC had returned to the original state.     

Lipids of Treponema pallidum Kazan 5

The lipid composition of Treponema pallidum Kazan 5 cultivated in a lipid-defined medium was investigated. Lipids comprised 18 to 20% of the dry weight of the treponeme. Glycolipid and phospholipids accounted for 90 to 95% of the total lipids and free fatty acids made up the remaining 5 to 10%. The major polar lipids were the glycolipid, 1-(O-alpha-d-galactopyranosyl)-2,3-diglyceride (45 to 55%), and phosphatidylcholine (30 to 40%). Phosphatidylethanolamine (5 to 10%), an unidentified compound (1 to 2%), and occasional trace amounts of diphosphatidylglycerol (cardiolipin) were also found. The monogalactosyldiglyceride was also a major component (50%) of the lipids of the Reiter, Noguchi, and Nichols strains of T. pallidum. The fatty acid composition of Kazan 5 usually consisted of saturated and unsaturated fatty acids ranging from 14 to 18 carbons depending upon the fatty acids added to the culture medium. When the cells were cultivated on elaidic acid (trans-9-octadecenoic acid), their lipids contained only elaidic acid.     

Determination of cellular fatty acid compositions of various yeasts by gas-liquid chromatography.

The cellular fatty acid composition of 51 cultures of various species of yeasts was determined by gas-liquid chromatography. Analysis was done with a fused-silica gas-liquid chromatography capillary column, with resolution of all components including mono-, di-, and tri-unsaturated 18-carbon acids. The cultures were placed into one of four distinct gas-liquid chromatography groups on the basis of large quantitative differences in fatty acids. Group I contained only Saccharomyces species and group II only Torulopsis glabrata. Most Candida species were placed into group III, and group IV contained only basidiomycetous yeasts.     

Unusual fatty acid substitution in lipids and lipopolysaccharides of Helicobacter pylori.

Cellular fatty acids, phospholipid fatty acids, and lipopolysaccharide fatty acids of four strains of Helicobacter pylori were analyzed by gas-liquid chromatography. The presence of myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, 19-carbon cyclopropane fatty acid, beta-hydroxypalmitic acid, and beta-hydroxystearic acid was confirmed. In phospholipids, myristic acid and 19-carbon cyclopropane fatty acid were the major fatty acids. Hydroxy fatty acids and unsaturated fatty acids were not detected or occurred only in small amounts. The major fatty acids of lipopolysaccharides were stearic acid, beta-hydroxypalmitic acid, and beta-hydroxystearic acid. Unsaturated fatty acids and 19-carbon cyclopropane fatty acid were not found. The unusual compositions of H. pylori phospholipid and lipopolysaccharide fatty acids may have important implications for the taxonomy, physicochemical membrane properties, and biological activity of lipopolysaccharides.     

Reutilization of fatty acid carbons for lung lipid synthesis

The utilization of glucose, palmitate, and oleate for the synthesis of lung lipids was studied in isolated rat lungs. Lungs were ventilated with 5% CO2 in air and perfused for 100 min with a Krebs-Ringer bicarbonate buffer (pH 7.4), containing 3% fatty acid-free albumin and either 5.6 mM [U-14C]glucose or 0.25 mM [1-14C]palmitate, or 0.25 mM [1-14C]-oleate. At the end of 100 min of perfusion with these precursors, between 73 and 85% of total lipid 14C was recovered as phospholipid. Glucose carbon was mainly incorporated into triglyceride fatty acids (TG-FA) and phosphatidylcholine fatty acids (PC-FA) of 16- and 18-carbon chain length. After perfusion with [14C]palmitate and [14C]oleate, only 65 and 20% of 14C was recovered as PC 16-carbon and 18-carbon FA, respectively. The remaining 14C was mainly recovered as FA shorter than the 14C precursors. Schmidt degradation analysis of lipid FA demonstrated considerable labeling of alkyl carbons on perfusion with the carboxyl-labeled precursors, indicating that FA degradation products were used for synthesis of lipid FA. This process was enhanced on addition of glucose to the perfusate.     

Cellular fatty acids of Brucella canis and Brucella suis.

The cellular fatty acid composition of Brucella canis and Brucella suis was determined by gas-liquid chromatography. The presence of relatively large amounts of a 19-carbon cyclopropane fatty acid in B. suis was a major distinguishing feature between these organisms. The gas-liquid chromatography test for cellular fatty acids provides an additional criterion for the distinction of antigenically rough strains of B. suis which cannot be differentiated from B. canis by conventional procedures.     

Fatty acid supplementation protects pulmonary artery endothelial cells from oxidant injury

Although supplemental fatty acids have been shown to alter the susceptibility of experimental animals to oxidant gases, the relationship between the degree of tissue fatty acyl unsaturation and resistance to oxidant exposure remains undefined. Because vascular endothelial cells have been demonstrated to be sensitive cellular targets in oxidant-induced lung injury, we evaluated the effects of a supplemental fatty acid on the lipid composition and oxidant susceptibility of pulmonary artery endothelial cells (PAEC) in monolayer culture. PAEC were incubated in culture medium supplemented with an ethanolic solution of 0.1 mM cis-vaccenic acid (CVA), an 18-carbon monounsaturated fatty acid, or with the ethanol vehicle alone for 3 h. Cells were then exposed to either control or oxidant (hyperoxia: 95% O2; or hydrogen peroxide: 100 microM) conditions. Oxidant-induced cell injury was assessed by phase-contrast microscopy and by measuring the release of intracellular lactate dehydrogenase. Incubation with CVA increased the CVA content of PAEC lipids and protected cells from oxidant-induced injury for up to 72 h after supplementation. CVA had no effect on nonoxidant-induced cell injury. Although the mechanism by which CVA protects cells against oxidant injury remains undefined, evidence is presented that indicates the mechanism does not involve induction of antioxidant enzyme activity, alterations in the physical state of PAEC membranes, or enhancement of PAEC nucleic acid repair mechanisms. These results define a useful model for exploring the relationship between lipid composition and oxidant susceptibility and suggest that fatty acid modifications may constitute an important strategy for protecting cells against oxidant injury.     

Observations on the lipids ofOochoristica agamae (Cestoda)

An investigation of the lipids ofOochoristica agamae, an anoplocephalid cestode of theAgama lizard, was undertaken. Total lipids of the parasite accounted for 8.4% of the fresh weight; neutral lipids comprised 82.98% of the total, glycolipids, 5.01%, and phospholipids, 12.03%. The major lipid classes inO. agamae include triglycerides, cholesterol, phosphatidyl choline, and phosphatidyl ethanolamine. The 16-and 18-carbon fatty acids were predominant in the parasite. Hexadecenoic acid, usually found at low concentrations in the lipids of helminth parasites, was the most abundant of the 16-carbon fatty acids ofO. agamae (notably in the neutral lipid fraction). Although octadecatrienoic acid occurred only in trace amounts in the intestinal contents of the host, significant amounts of this fatty acid were detected in the parasite. A lack of 20-carbon fatty acids was determined in the lipids of the host's intestinal contents and the neutral lipid fraction of the parasite.O. agamae is suspected to be capable of modifying fatty acids obtained from dietary sources by chain elongation.     

Changes in erythrocyte membrane phospholipid composition induced by physical training and physical exercise

Summary The effects were investigated of physical training and exercise on lipids of the erythrocyte membrane of healthy students. Membrane cholesterol and phospholipids were analysed simultaneously by thin-layer chromatography with a flame ionization detector and the fatty acid composition was determined by gas chromatography. Physically trained students had similar physical characteristics to control students but a significantly higher aerobic capacity, estimated as the maximal oxygen uptake and anaerobic threshold. Of the phospholipids examined, only the content of membrane phosphatidylserine was significantly lower in the trained group. Fatty acid analysis showed that the amount of docosahexaenoic acid in membrane phosphatidylserine was lower in the trained group. There was no significant difference between the fatty acid compositions of membrane phosphatidylcholine in the two groups. Maximal exercise decreased membrane phosphatidylserine in the control group but not in the trained group. It also significantly decreased the relative amounts of unsaturated fatty acids in both phosphatidylcholine and phosphatidylserine in the untrained group. Maximal oxygen uptake was negatively correlated with the amount of erythrocyte membrane phosphatidylserine. These results would indicate that both physical training and acute exercise decrease phosphatidylserine and polyunsaturated fatty acids in erythrocyte membranes, possibly due to lipid peroxidation, suggesting limited enhancement of erythrocyte defense mechanisms in adaptation to chronic oxidative stress.     

Distinct lipid compositions of parasite and host cell plasma membranes from Plasmodium chabaudi-infected erythrocytes

Mouse erythrocytes infected with early or late trophozoites of the malaria parasite Plasmodium chabaudi were fractionated into free parasites and host cell plasma membranes, and both fractions were analyzed for cholesterol content and the composition of phospholipids and total fatty acids. The major results are: (i) parasites contain only a very low level of cholesterol which is about one-tenth of that of host cell plasma membranes. (ii) Parasites also contain less sphingomyelin and phosphatidylserine as well as more phosphatidylcholine than host cell plasma membranes. (iii) Parasites contain less 18:0 and 18:1 and more 18:2 and 20:4 fatty acids than host cell plasma membranes. (iv) During intraerythrocytic growth of parasites from early to late trophozoites, the relative proportions of cholesterol and phospholipids remain largely unchanged in both parasites and host cell plasma membranes. However, significant changes occur in the fatty composition of both compartments. There is an increase in the 20:4 and a decrease in the 18:0 and 18:1 fatty acids. (v) Plasma membranes of infected and non-infected erythrocytes exhibit about the same cholesterol content and phospholipid composition, but differ in the total fatty acid composition. Our data suggest the existence of distinct mechanisms controlling the different lipid compositions of parasites and host cell plasma membranes in whole Plasmodium chabaudi-infected erythrocytes during intraerythrocytic development of parasites, though both compartments are known to depend on the supply of various lipids from the host.     

Chemical characterization of clinical isolates which are similar to CDC group DF-3 bacteria.

Six clinical isolates, taken from blood or wounds, that had biochemical characteristics most similar to Centers for Disease Control group DF-3 bacteria were examined for cellular fatty acid composition and isoprenoid quinone content to evaluate their chemical relatedness to known bacterial species and groups. The fatty acids were liberated from whole cells by base hydrolysis, methylated, and analyzed by capillary gas-liquid chromatography. The isoprenoid quinones were extracted from lyophilized whole cells and analyzed by reverse-phase high-performance liquid chromatography. All six strains, which were designated group DF-3-like, possessed a distinct fatty acid profile that was characterized by large amounts (greater than 20%) of 13-methyltetradecanoate (i-C15:0) and 12-methyltetradecanoate (a-C15:0), moderate amounts of saturated branched-chain 13-carbon acids (i-C13:0 and a-C13:0) and hexadecanoate (n-C16:0), and small to moderate amounts of both branched- and straight-chain hydroxy acids (i-3-OH-C15:0, 3-OH-C16:0, i-3-OH-C17:0, and 2-OH-C17:0). This fatty acid profile was unique compared with the profiles of group DF-3 and other bacteria we have previously tested and is useful for the rapid identification of group DF-3-like isolates. The isoprenoid quinone content of four group DF-3-like strains was similar, with ubiquinone-9 (Q-9) and Q-10 as their major quinones, while the other two group DF-3-like strains contained Q-7 as their major quinones, with smaller amounts of Q-8 and Q-9.     

Preliminary studies of lipids of the trematodes Eurytrema pancreaticum,Calicophoron erschowi and the turbellarian Penecurva sibirica

The amount of total lipids, phospholipids, neutral lipids and fatty acids was determined in cattle parasites, namely the trematodes Eurytrema pancreaticum, Calicophoron erschowi, and in the free-living turbellarian Penecurva sibirica. Neutral lipids of these flatworms contained sterols, sterol esters, triacylglycerols and free fatty acids. P. sibirica also contained diacylglycerols.Parasitic and free-living flatworms differed in phospholipid composition: the turbellarian did not contain phosphatidylserine, and the trematodes had practically no sphingomyelin or lysophosphatidyl choline. E. pancreaticum, C. erschowi and P. sibirica contained high levels of phosphatidylcholine and phosphatidylethanolamine as well as lysophosphatidylethanolamine and cardiolipin.The fatty acid composition of total lipid extracts of flatworms and of the pancreas and rumen of the host animals were determined. The fatty acid composition of the flatworm lipids reflected the fatty acid composition of the host tissue but was not identical to it.     

Subgrouping of Pseudomonas cepacia by cellular fatty acid composition.

The cellular fatty acid compositions were determined for 42 strains of Pseudomonas cepacia from five cystic fibrosis centers in North America. All isolates contained significant (20%) amounts of hexadecanoic (C16:0), and cis-9 hexadecenoic (C16:1 cis9) acids and an isomer of octadecenoic acid (C18:1). None had hydroxy acids containing fewer than 14 carbon atoms. The quantitative data from the fatty acid analysis were highly reproducible and provided a basis for numerical analysis. Five subgroups comprising all the strains were obtained by cluster analysis and further characterized by principal-component analysis. With minor exceptions, the predominant subgroup identified in each center was different from that identified in other centers and accounted for one-half of the isolates within each center. Cellular fatty acid composition is a useful adjunct to biochemical characterization for the identification of P. cepacia isolated from cystic fibrosis patients. Numerical analysis of the fatty acid data can separate P. cepacia into subgroups, which may provide useful epidemiologic information or a basis for further analysis by more complex techniques such as DNA probe analysis.     

Age-dependent alterations in lipids and function of rat heart sarcolemma

The objective of the present study was to examine the effect of age on heart sarcolemma structure and function. Sarcolemmal fractions were prepared from hearts of young (1–1.5 months) and adult (10–12 months) rats and assayed for marker enzyme activities. The membrane fractions were found to be devoid of other cellular organelles upon examination by electron microscopy. They were enriched with 5′-nucleotidase and devoid of succinate dehydrogenase activity. The only age-related lipid compositional changes noted in these membranes were changes in the fatty acid composition of membrane phospholipids with increasing age. Most changes were detected in phosphatidylcholine and phosphatidylethanolamine with very little alteration of sphingomyelin and phosphatidylserine plus phosphatidylinositol fatty acids. Polyunsaturated fatty acids, especially 18:2 and 20:4, were decreased with saturated fatty acids increased in membrane phosphatidylcholine and phosphatidylethanolamine fractions as the animal develops. There was a decrease in the specific activities of(Na⁺ + K⁺)-ATPase and 5′-nucleotidase of these membranes with age. On the other hand, membrane (K⁺)-p-nitrophenylphosphatase was not affected by age.