Postnatal development of phospholipids and their fatty acid profile in rat heart

The aim of this study was to determine the concentration of phospholipids (PL), plasmalogen components of choline (PC) and ethanolamine (PE) phosphoglycerides (PLPC, PLPE) and fatty acid profile of PL and triacylglycerols (TAG) in developing rat left ventricular myocardium between postnatal day (d) 2 and 100. The steepest increase of total PL (TPL) concentration occurs between d2 and d5, followed by a further slower increase between d20 and d40. Similar developmental changes were observed in PC and PE. The PLPE concentration rises by d10, whereas PLPC does not change during the whole period investigated, except for the transient decline on d5. The concentration of diphosphatidylglycerol (DPG) increases by d60; the steepest rise occurs between d20 and d40. Phosphatidylinositol (PI) concentration rises only by d5. The concentration of phosphatidylserine (PS) decreases between d5 and d10 and then it does not change. Sphingomyelin (SM) concentration is maintained till d10, it declines on d20 and does not change thereafter. The proportion of saturated fatty acids (SFA) increases by d5 in PC, PE, PS and TAG, and by d10 in DPG and PI. After d20 the SFA proportion gradually decline in all lipids. Monounsaturated FA (MUFA) proportion decreases in PC, PE, PI and PS from d2 till d10, and in the weaning period it tends to rise again. In contrast, in DPG and TAG the proportion of MUFA declines during the whole postnatal period. N-6 polyunsaturated FA (PUFA) decrease in all PL by d20 and rise again thereafter; in TAG they decline between d2 and d10 and return to the initial level by d100. N-3 PUFA increase in all PL during the suckling period and decline after weaning; in TAG they increase only by d5 and then they decline. This remodeling of myocardial PL and TAG composition during postnatal development may affect membrane properties and contribute to developmental changes in the function of membrane proteins and cell signaling.     

K-FGF mediated transformation and induction of metastatic potential involves altered ornithine decarboxylase and S-adenosylmethionine decarboxylase expression – role in cellular invasion

Adult male Wistar rats were exposed to intermittent high altitude hypoxia of 7000 m simulated in a hypobaric chamber for 8 h/day, 5 days a week; the total number of exposures was 25. The concentration of individual phospholipids and their fatty acid (FA) profile was determined in right (RV) and left (LV) ventricles. Adaptation to hypoxia decreased the concentration of diphosphatidylglycerol (DPG) in hypertrophied RV by 19% and in non-hypertrophied LV by 12% in comparison with normoxic controls. Chronically hypoxic hearts exhibited lower phospholipid n-6 polyunsaturated FA (PUFA) content mainly due to decreased linoleic acid (18:2n-6), which was opposed by increased n-3 PUFA mainly due to docosahexaenoic acid (22:6n-3) in phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylinositol (PI). The content of arachidonic acid (20:4n-6) was unchanged in total phospholipids, but in PC it was increased in both ventricles (by 22%) and in PE decreased in LV only (by 20%). Chronic hypoxia increased the un-saturation index of PC and PE in both ventricles. The content of monounsaturated FA (MUFA) was increased and 18:2n-6 decreased in DPG. The proportion of saturated FA was increased in PC and PI of hypoxic RV but not LV. The FA composition of phosphatidylserine was not altered in hypoxic ventricles. It is concluded that chronic hypoxia led to only minor changes in individual phospholipid concentration in rat ventricular myocardium, but markedly altered their FA profile. These changes, in particular the greater incorporation of n-3 PUFA into phospholipids and increased un-saturation index, may lead to a better preservation of membrane integrity and thereby contribute to improved ischemic tolerance of chronically hypoxic hearts.     

Regulation of β-adrenoceptor properties and the lipid milieu in heart muscle membranes during stress

The purpose of this study was to examine changes in fatty acyl chain composition of major cardiac phospholipids in relation to down-regulation of -adrenoceptors during various forms of stress or chronic adrenergic stimulation. Analysis of the fatty acid profile of phosphatidylcholine (PC) and phosphatidylethanolamine (PE) in sarcolemma or cardiac muscle membranes showed partial replacement of 18:2n-6 by 20:4n-6 in PC and replacement of both 18:2n-6 and 20:4n-6 by 22:6n-3 in PE during daily administration of epinephrine or norepinephrine for 7 or 15 days, respectively These changes in membrane PC and PE coincided with down-regulation or the decrease in Bmax of -adrenoceptors during adrenergic stimulation. Cardiac membrane response to other forms of stress or chronic adrenergic stimulation such as neonatal stress, restriction stress or restricted food intake was expressed in the same way, that is replacement of 18:2n-6 by 20:4n-6 in PC and replacement of 18:2n-6 and 20:4n-6 by 22:6n-3 in PE.Conclusion: Adaptation to stress includes a decrease in the density of binding sites or down-regulation of -adrenoceptors in sarcolemma synchronized with specific alterations in the fatty acyl chain composition within the membrane bilayer. The changes in the lipid milieu of the membrane may facilitate conformational changes in the transmembrane segment of the receptor forming the ligand binding sites of the -adrenoceptor.     

Direct effects of temperature on phospholipid and polyunsaturated fatty acid metabolism in isolated brain cells from rainbow trout, Oncorhynchus mykiss.

1. The direct effects of temperature on the metabolism of [1-14C]18:2(n-6), [1-14C]18:3(n-3), [1-14C]20:4(n-6) and [1-14C]20:5(n-3) were studied in isolated brain cells from rainbow trout, Oncorhynchus mykiss. 2. Recovery of radioactivity from all the polyunsaturated fatty acids (PUFA) in total lipid was significantly greater at 5 and 15 degrees C than at 25 degrees C. 3. The lower incubation temperatures decreased the relative net incorporation of all the 14C-labelled PUFA into phosphatidylcholine (PC) and increased the relative incorporation of the PUFA into the other phosphoglycerides, especially phosphatidylethanolamine (PE). 4. The effects on PC were generally more significant between 25 and 15 degrees C, whereas the effects on PE were generally significant both between 25 and 15 degrees C and between 15 and 5 degrees C. 5. This suggests that the lysophospholipid acyltransferases responsible for the incorporation of PUFA into different phosphoglycerides may have differential sensitivities to temperature. 6. In contrast, the acyltransferase activities showed fatty acyl preferences that were independent of temperature. 7. Although a trend towards decreased activity at 5 degrees C was apparent, temperature generally had little significant effect on the relative percentages of the PUFA metabolized via the desaturase pathways.     

Effect of L-triiodothyronine on liver microsomal Δ6 and Δ5 desaturase activity of male rats

The effect of different doses of L-triiodothyronine (T₃) on the activity of 6 and 5 desaturases and lipid fatty acid composition was studied in liver microsomes of male rats. The activity of 6 and 5 desaturases was decreased 24 and 28%, respectively, in animals administered a daily intraperitoneal dose of 1000g T₃/100g body wt. for 5 days, whereas with 500g T₃/100g body wt. only 6 desaturase activity was decreased. On the other hand, no enzyme activity changed at a shorter period of hormone treatment. Changes in microsomal fatty acid composition did not seem to be a direct consequence of desaturation activity, since after 1 and 5 days of T₃ treatment, the concentrations of 18:2 (n-6) and 20:3 (n-6) decreased and only after 1 day that of 20:4 (n-6) increased in spite of unchanged or decreased 6 and 5 desaturase activities. Other factors than desaturation activity must be involved in fatty acid composition of thyroid hormonetreated rats, such as diet, membrane lipid synthesis and degradation, fatty acid turn-over and oxidation. (Mol Cell Biochem121: 149–153, 1993)     

Leptin,NPY, Melatonin and Zinc Levels in Experimental Hypothyroidism and Hyperthyroidism: The Relation to Zinc

Since zinc mediates the effects of many hormones or is found in the structure of numerous hormone receptors, zinc deficiency leads to various functional impairments in the hormone balance. And also thyroid hormones have important activity on metabolism and feeding. NPY and leptin are affective on food intake and regulation of appetite. The present study is conducted to determine how zinc supplementation and deficiency affect thyroid hormones (free and total T3 and T4), melatonin, leptin, and NPY levels in thyroid dysfunction in rats. The experiment groups in the study were formed as follows: Control (C); Hypothyroidism (PTU); Hypothyroidism+Zinc (PTU+Zn); Hypothyroidism+Zinc deficient; Hyperthyroidism (H); Hyperthyroidism+Zinc (H+Zn); and Hyperthyroidism+Zinc deficient. Thyroid hormone parameters (FT₃, FT₄, TT₃, and TT₄) were found to be reduced in hypothyroidism groups and elevated in the hyperthyroidism groups. Melatonin values increased in hyperthyroidism and decreased in hypothyroidism. Leptin and NPY levels both increased in hypo- and hyperthyroidism. Zinc levels, on the other hand, decreased in hypothyroidism and increased in hyperthyroidism. Zinc supplementation, particularly when thyroid function is impaired, has been demonstrated to markedly prevent these changes.     

Lipid composition of the three co-existing <Emphasis Type="Italic">Calanus</Emphasis> species in the Arctic: impact of season,location and environment

Arctic species of Calanus are critical to energy transfer between higher and lower trophic levels and their relative abundance, and lipid content is influenced by the alternation of cold and warm years. All three species of Calanus were collected during different periods in Kongsfjorden (Svalbard, 79°N) and adjacent shelf during the abnormally warm year of 2006. Lipid composition and fatty acid structure of individual lipid classes were examined in relation with population structure. Wax esters dominated the neutral lipid fraction. Phosphatidylcholine (PC) dominated the structural lipids followed by phosphatidylethanolamine (PE). PC/PE ratios of 3–6 suggested an increase in PC proportions compared to earlier studies. Depending on the time scale, fatty acids of wax esters illustrated either trophic differences between fjord and offshore conditions for C. hyperboreus and C. finmarchicus or trophic differences related to seasonality for C. glacialis. Similarly, seasonality and trophic conditions controlled the changes in fatty acids of triglycerides, but de novo synthesis of long-chain monoenes suggested energy optimization to cope with immediate metabolic needs. Polar lipids fatty acid composition was species specific and on the long-term (comparison with data from the past decade) composition appears related to changes in trophic environment. Fatty acid composition of PC and PE indicated relative dominance of 20:5n-3 in PC and 22:6n-3 in PE for all three species. The combination of PE and PC acyl chain and phospholipid head group restructuring indicates an inter-annual variability and suggests that membrane lipids are the most likely candidate to evaluate adaptive changes in Arctic copepods to hydrothermal regime.     

Sex-specific phenotypes of hyperthyroidism and hypothyroidism in mice

Background

Thyroid dysfunction is more common in the female population, however, the impact of sex on disease characteristics has rarely been addressed. Using a murine model, we asked whether sex has an influence on phenotypes, thyroid hormone status, and thyroid hormone tissue response in hyper- and hypothyroidism.

Methods

Hypo- and hyperthyroidism were induced in 5-month-old female and male wildtype C57BL/6N mice, by LoI/MMI/ClO₄ ^? or T₄ i.p. treatment over 7 weeks, and control animals underwent sham treatment (N?=?8 animals/sex/treatment). Animals were investigated for impact of sex on body weight, food and water intake, body temperature, heart rate, behaviour (locomotor activity, motor coordination, and strength), liver function, serum thyroid hormone status, and cellular TH effects on gene expression in brown adipose tissue, heart, and liver.

Results

Male and female mice showed significant differences in behavioural, functional, metabolic, biochemical, and molecular traits of hyper- and hypothyroidism. Hyperthyroidism resulted in increased locomotor activity in female mice but decreased muscle strength and motor coordination preferably in male animals. Hypothyroidism led to increased water intake in male but not female mice and significantly higher serum cholesterol in male mice. Natural sex differences in body temperature, body weight gain, food and water intake were preserved under hyperthyroid conditions. In contrast, natural sex differences in heart rate disappeared with TH excess and deprivation. The variations of hyper- or hypothyroid traits of male and female mice were not explained by classical T₃/T₄ serum state. TH serum concentrations were significantly increased in female mice under hyperthyroidism, but no sex differences were found under eu- or hypothyroid conditions. Interestingly, analysis of expression of TH target genes and TH transporters revealed little sex dependency in heart, while sex differences in target genes were present in liver and brown adipose tissue in line with altered functional and metabolic traits of hyper- and hypothyroidism.

Conclusions

These data demonstrate that the phenotypes of hypo- and hyperthyroidism differ between male and female mice and indicate that sex is an important modifier of phenotypic manifestations.

     

The molecular species of phospholipids of the cold-water soft coral <Emphasis Type="Italic">Gersemia rubiformis</Emphasis> (Ehrenberg, 1834) (Alcyonacea,Nephtheidae)

The chemical structures and contents of 68 molecular species of ethanolamine glycerophospholipids (PE), choline glycerophospholipids (PC), serine glycerophospholipids (PS), and inositol glycerophospholipids (PI) were determined in the asymbiotic soft coral Gercemia rubiformis (Ehrenberg, 1834) from the Sea of Okhotsk by the method of tandem high-resolution mass spectrometry. The major molecular species were 16:1e/20:4 PE, 16:0e/20:4 PC, 20:1/24:5 PS, and 16:0/24:5 PI. This study showed a significant similarity of the polar lipidomes of G. rubiformis and tropical species of alcyonarians with symbiotic microalgae and revealed the basic characteristic of the polar lipidome of these alcyonarians. It was found that the 24:5n-6 and 24:6n-3 acids (chemotaxonomic markers of soft corals) concentrate in the acyl groups of the molecular species of PS and PI, which can be used as molecular lipid markers in the study of the symbiotic and trophic relationships of soft corals.     

Dietary linoleic acid affects phospholipid fatty acid composition in heart and eicosanoid production by cardiomyocytes from atlantic salmon (Salmo salar)

• 1.1. Atlantic salmon post-smolts were fed practical-type diets containing linoleic acid at 10, 25 or 45% of total dietary fatty acids for a period of 20 weeks.
• 2.2. As dietary linoleic acid was increased, individual phospholipids of heart contained increased levels of 18:2n-6, 20:2n-6, 20:3n-6 and 20:4n-6 and reduced levels of 20:5n-3. The ratio of n-3/n-6 polyunsaturated fatty acids in heart phospholipids decreased and the ratio of 20:4n-6/20:5n-3 increased.
• 3.3. An increased production of thromboxane B₂ occurred in isolated cardiac myocytes from fish given the highest dietary linoleic acid but the production of 6-keto prostaglandin F_1α was not significantly affected, nor was the activity of heart sarcoplasmic reticulum Ca²⁺-Mg²⁺ ATPase (EC 3.6.1.4).

     

<Emphasis Type="Italic">Ensifer collicola</Emphasis> sp. nov., a bacterium isolated from soil in South Korea

Strain Mol12^T, which presented in the form of Gram-negative, motile, non-spore forming rod-shaped, was isolated from soil in South Korea and characterized to determine its taxonomic position. The strain grew at 20–30°C (optimum 30°C) and pH 7.0–10.0 (optimum pH 8.0) with 1% (w/v) NaCl. Phylogenetic analysis based on 16S rRNA gene sequences showed that the strain Mol12^T was most closely related to Ensifer terangae LMG 7834^T (96.78%), Rhizobium daejeonense KCTC 12121^T (96.43%), Ensifer adhaerens Casida A^T (96.28%). Chemotaxonomic data showed that the predominant fatty acids were Summed Feature 8 (C_18:1 ω7c and/or C_18:1 ω6c; 53.02%) and C_18:1 ω7c 11-methyl (24.01%). Its complex polar lipid contained major amounts of diphosphatidylglycerol (DPG), phosphatidylethanolamine (PE) and Q-10 as the predominant ubiquinone. The DNA G+C content of strain Mol12^T was determined to be 60.9 mol%. Based on the phylogenetic, chemotaxonomic, and phenotypic data, strain Mol12^T (=KCTC 42816^T =JCM 31049^T) ought to be classified as a type strain of a novel species, for which the name Ensifer collicola sp. nov. is proposed.     

Adaptation of biological membranes to temperature: molecular species compositions of phosphatidylcholine and phosphatidylethanolamine in mitochondrial and microsomal membranes of liver from thermally-acclimated rainbow trout

Summary Molecular species profiles were determined for both phosphatidylcholine (PC) and phosphatidylethanolamine (PE) of mitochondrial and microsomal membrane fractions from liver tissue of thermally-acclimated rainbow trout,Salmo gairdneri. The predominant molecular species of PC were 16:0/22:6, 16:0/18:1, 16:0/20:3 and 16:0/22:5, whereas predominant molecular species of PE were 18:1/20:4, 14:0/16:0, 18:0/22:6 and 18:1/22:6. PE possessed short chain saturates (primarily 14:0/16:0) and monoenes (primarily 14:0/16:1) not present in PC and larger proportions of polyunsaturated (18:0/22:6, 18:0/22:5 and 18:1/22:6. and diunsaturated molecular species than PC. Differences between membrane fractions were most evident in warm (20°C)-acclimated trout. Mitochondria contained higher proportions of long-chain, polyunsaturated molecular species of PE, but less of the corresponding species of PC than other membrane fractions. Rankings based on unsaturation index were accordingly: mitochondria heavy microsomes>light microsomes for PE, but heavy microsomes>light microsomes>-mitochondria for PC. Mitochondria were notable for high proportions of diunsaturated molecular species of both phosphatides. Growth at cold temperatures (5°C) was generally associated with a replacement of shorter chain mono- and dienoic molecular species (16:0/18:1, 16:1/18:1, 14:0/16:2 and 18:1/18:1 in the case of PC and 14:0/16:1, 14:0/16:2 and 16:1/18:1 for PE), and occasionally saturates, with long-chain, polyunsaturated molecular species (for PC, C_36–38: 16:0/22:6, 16:1/22:6, 16:0/20:3 and 16:0/20:5; for PE, C_38–40: 18:1/20:4, 16:1/22:6, 18:0/20:5, 18:2/20:4, 18:0/22:5 and 18:0/22:6). However, compositions of mitochondrial PE and PC from heavy microsomes were not significantly influenced by acclimation temperature. The role of phospholipase A₂, in addition to other metabolic processes, in mediating these changes is discussed.Abbreviations ACL average chain length - UI unsaturation index     

Metabolism of n-6 fatty acids by NIH-3T3 cells transfected with the ras oncogene

N-6 fatty acid metabolism was compared in NIH-3T3 cells and DT cells, which differ only in the presence of the v-Ki-ras oncogene. Non-dividing cells were incubated with [1-¹⁴C]-labelled fatty acids (18:2n-6, 18:3n-6, 20:3n-6 and 20:4n-6) at different time intervals (2–24 h) and concentration (0–120 M). In both cells lines, the uptake of different fatty acids from the medium was similar and reached a maximum at 6–8 h. All fatty acids reached the same maximum level in DT cells, whereas, the relative uptake of added fatty acids by NIH-3T3 cells was different: 20:4n-6>20:2n-6>18:2n-6=18:3n-6. Throughout the incubation (2–24 h), desaturation and elongation of n-6 fatty acids was more active in DT cells than in NIH-3T3 cells. However, in both cell lines, incubated with different n-6 fatty acid precursors, the levels of radiolabelled 20:4n-6 were relatively constant. In DT cells, phosphatidylcholine was found to be the major fraction labelled with n-6 fatty acids precursors and those of endogenous synthesis, whereas, in NIH-3T3 cells the neutral lipid fraction, particularly triglycerides, was also strongly labelled. In concentration dependent studies, phospholipid labelling by fatty acids was saturable. At lower concentrations, especially in DT cells, phospholipids were labelled predominantly. As the concentration increased there was an overflow into the triglyceride fraction. Since the differences in fatty acid metabolism between the two cell lines cannot be related to the growth rate, it is suggested that they were a consequence of the expression of the v-Ki-ras oncogene.Abbreviations BSA bovine serum albumin - CE cholesterol ester - DG diglyceride - DMEM Dulbecco's modification of Eagle's medium - EL ether lipids (glyceryl ether diesters) - FAME fatty acid methyl ester - FCS fetal calf serum - FFA free fatty acids - HEPES N-2-(hydroxyethyl)piperazine-N-2-ethanesulphonic acid - MG monoglyceride - NL neutral lipid - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PL phospholipid - s.a specific activity - TG triglyceride - TLC thin layer chromatography     

Deficit of didocosahexaenoyl phospholipid in the eyes of larval sea bass fed an essential fatty acid deficient diet

Larval sea bass Dicentrarchus labrax of 27 days old were reared on Artemia enriched with Super Selco©, Tuna Orbital Oil or Yeast. The first diet is commonly used in mariculture for larval rearing, the second diet was designed to deliver an optimal docosahexaenoic acid (22: 6n-3) to eicosapentaenoic acid (20: 5n-3) ratio, and the third diet was deficient in docosahexaenoic acid (22: 6n-3). The eyes of these larvae were analysed after 28 days and the molecular species of the three main phospholipid classes, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) determined. Eyes from larvae fed Artemia enriched with yeast showed large decreases in molecular species containing 22: 6n-3 compared to those supplemented with tuna orbital oil, most notably in 16: 0/22: 6n-3 PC which fell from 10.6 to 0.4%, in 22: 6n-3/22: 6n-3 and 18: 1/22: 6n-3 PE which fell from 29.6 to 0.3% and from 10.8 to 1.1% respectively, and in 22: 6n-3/22: 6n-3 PS which fell from 34.3 to 1.7%. Molecular species containing all other fatty acids, and especially 20: 5n-3, were elevated in eyes from the yeast-supplemented fish. In larvae fed Artemia enriched with Super Selco, amounts of eye 22: 6n-3/22: 6n-3 phospholipid were slightly lower in all three phospholipid classes compared to eyes from the tuna orbital oil-supplemented larvae. There was also a trend of decreased saturated fatty acid/22: 6n-3 and monounsaturated fatty acid/22: 6n-3 molecular species in all classes from the Super Selco-supplemented fish, the deficits being made up with molecular species containing 20: 5n-3 and 22: 5n-3. These results are discussed in relation to larval viability with particular respect to visual function.     

SYNAPTOSOMAL PLASMA MEMBRANES. ACYL GROUP COMPOSITION OF PHOSPHOGLYCERIDES and (Na++ K+)-ATPase ACTIVITY DURING FATTY ACID DEFICIENCY

Abstract— Essential fatty acid deficiency was induced in mice after feeding a fatty acid deficient diet for 6 months. Activity of the (Na⁺+ K⁺)-ATPase in the total brain homogenates and in isolated synaptosomal plasma membranes was significantly higher ( P & lt; 0 05) in the deficient mice than the controls. Analysis of the acyl group composition of phosphoglycerides in brain as well as in the synaptosomal plasma membranes showed that mice fed the deficient diet had increased levels of 20:3(n-9) and 22:3(n-9) and decreased levels of 20:4(n-6) and 22:4(n-6). However, acyl group changes varied among individual phosphoglycerides and were most obvious in the two species of ethanolamine phosphoglycerides. A decrease in 22:6(n-3) level was also observed in some phosphoglycerides of the synaptosomal plasma membranes especially the diacyl- sn -glycerophosphorylserine. In this experiment, a new solvent system for chromatographic separation of the diacyl- sn -glycerophosphorylserine and diacyl- sn -glycerophosphorylinositol was reported. The separation technique was suitable for analysis of acyl group composition of individual phosphoglycerides by gas-liquid chromatography. The results were consislent with a positive correlation of the non-polar acyl groups of brain membranes with the active ion transport activity. The increase in enzymic activity during deficient state may be the result of a biological adaptation due to structural alteration of the brain membranes.     

Fatty Acid Composition of Human Brain Phospholipids During Normal Development

Abstract: The fatty acid composition of phosphatidylethanolamine (PE), ethanolamine plasmalogens (EPs), phosphatidylserine (PS), phosphatidylcholine (PC), and sphingomyelin was studied in 22 human forebrains, ranging in age from 26 prenatal weeks to 8 postnatal years. Phospholipids were separated by two-dimensional TLC, and the fatty acid methyl esters studied by capillary column GLC. Docosahexaenoic acid (22:6n-3) increased with age in PE and PC, whereas arachidonic acid (20:4n-6) remained quite constant. In EP, 22:6n-3 increased less markedly than 20:4n-6, adrenic (22:4n-6) and oleic (18:1n-9) acids being the predominant fatty acids during postnatal age. In PS, 18:1n-9 increased dramatically throughout development, and 20:4n-6 and 22:4n-6 increased only until ∼6 months of age. Although 22:6n-3 kept quite constant during development in PS, its percentage decreased due to the accretion of other polyunsaturated fatty acids (PUFAs). As a characteristic myelin lipid, sphingomyelin was mainly constituted by very long chain saturated and monounsaturated fatty acids. Among them, nervonic acid (24:1n-9) was the major very long chain fatty acid in Sp, followed by 24:0, 26:1n-9, and 26:0, and its accretion after birth was dramatic. As myelination advanced, 18:1n-9 increased markedly in all four glycerophospholipids, predominating in EP, PS, and PC. In contrast, 22:6n-3 was the most important PUFA in PE in the mature forebrain.     

Selective changes to phosphatidylcholine and phosphatidylethanolamine molecular species in the developing fetal guinea pig liver and plasma

The molecular species composition of membrane phospholipids influences the activities of integral proteins and cell signalling pathways. We determined the effect of increasing gestational age on fetal guinea pig liver phosphatidylcholine (PC) and phosphatidylethanolamine (PE), and plasma PC molecular species composition. The livers were collected from fetuses (n = 5/time point) at 5 day intervals between 40 and 65 days of gestation, and at term (68 days). Hepatic PC and PE molecular species composition was determined by electrospray ionisation mass spectrometry. An increasing gestational age was accompanied by selective changes in individual molecular species. The proportion of the sn-1 18:0 species increased relative to the sn-1 16:0 species in liver PC, but not PE, with an increasing gestational age. 1-O-alkyl-2-acyl PC species concentrations decreased significantly between 40 and 45 days of gestation (40%), and 65 and 68 days (54%). Total 1-O-alkenyl-2-acyl PE species concentration increased between days 60 and 65, due to a rise in 1-O-16:0 alkyl/20:4 content, and then decreased until term. Between day 40 and term, PC and PE sn-2 18:2n-6 species concentrations increased 3-fold. PC16:0/18:2 increased gradually throughout gestation, while PC18:0/18:2 content only increased after day 65. The overall increase in PE18:2n-6 content was due to PE18:0/18:2 alone. The composition of plasma PC essentially reflected hepatic PC. Overall, these data suggest differential regulation of hepatic PC and PE molecular species composition during development which is essentially independent of the maternal fatty acid supply.     

Fatty acid composition of individual polar lipid classes from marine macrophytes

Major glycolipids [monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG)) and phospholipids (phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylglycerol (PG)] as well as betaine lipid 1,2-diacylglycero-O-4'-(N,N,N-tri-methyl)-homoserine (DGTS) were isolated from Anfeltia tobuchiensis (Rhodophyta), Laminaria japonica, Sargassum pallidum (Phaeophyta), Ulva fenestrata (Chlorophyta) and Zostera marina (Embriophyta), harvested in the Sea of Japan. GC analysis of their fatty acid (FA) composition revealed that the n-6 polyunsaturated FAs (PUFAs) shared the most part of the sum of n-6 and n-3 PUFAs in PC and PE compared with glycolipids and PG. In algae, it was related to the prevalence of 20:4n-6 over 20:5n-3 in non-photosynthetic lipids. Percentage of n-6 PUFAs as well as the sum of n-3 and n-6 PUFAs decreased in the following sequence: PC-->PE-->PG. The saturation increased in the lines of MGDG-->DGDG-->SQDG and PC-->PE-->PG. PG was close to SQDG by the level of saturation. Distribution of C(18) and C(20) PUFAs in polar lipids depended on taxonomic position of macrophytes. Balance between C(18) and C(20) PUFAs was preferably shifted to the side of C(20) PUFAs in PC and PE that was observed in contrast to glycolipids and PG from L. japonica containing both series of FAs. The set of major FAs of polar lipid classes can essentially differ from each other and from total lipids of macrophytes. For example, MGDG was found to accumulate characteristic fatty acids 16:4n-3, 16:3n-3, 18:3n-6 and 18:4n-3, 20:3n-6 in U. fenestrata, Z. marina, L. japonica and S. pallidum, respectively.     

Determination of membrane cholesterol partition coefficient using a lipid vesicle-cyclodextrin binary system: effect of phospholipid acyl chain unsaturation and headgroup composition

Lateral domain or raft formation in biological membranes is often discussed in terms of cholesterol-lipid interactions. Preferential interactions of cholesterol with lipids, varying in headgroup and acyl chain unsaturation, were studied by measuring the partition coefficient for cholesterol in unilamellar vesicles. A novel vesicle-cyclodextrin system was used, which precludes the possibility of cross-contamination between donor-acceptor vesicles or the need to modify one of the vesicle populations. Variation in phospholipid headgroup resulted in cholesterol partitioning in the order of sphingomyelin (SM) > phosphatidylserine > phosphatidylcholine (PC) > phosphatidylenthanolamine (PE), spanning a range of partition DeltaG of -1181 cal/mol to +683 cal/mol for SM and PE, respectively. Among the acyl chains examined, the order of cholesterol partitioning was 18:0(stearic acid),18:1n-9(oleic acid) PC > di18:1n-9PC > di18:1n-12(petroselenic acid) PC > di18:2n-6(linoleic acid) PC > 16:0(palmitic acid),22:6n-3(DHA) PC > di18:3n-3(alpha-linolenic acid) PC > di22:6n-3PC with a range in partition DeltaG of 913 cal/mol. Our results suggest that the large differences observed in cholesterol-lipid interactions contribute to the forces responsible for lateral domain formation in plasma membranes. These differences may also be responsible for the heterogeneous cholesterol distribution in cellular membranes, where cholesterol is highly enriched in plasma membranes and relatively depleted in intracellular membranes.