Minor Lipid Components Research Articles

Common Sources and Estimated Intake of Plant Sterols in the Spanish Diet

Plant sterols (PS) are minor lipid components of plants, which may have potential health benefits, mainly based in their cholesterol-lowering effect. The aim of this study was to determine the composition and content of PS in plant-based foods commonly consumed in Spain and to estimate the PS intake in the Spanish diet. For this purpose, the determination of PS content, using a modern methodology to measure free, esterified, and glycosidic sterol forms, was done. Second, an estimation of the intake of PS, using the Spanish National Food Consumption data, was made. The daily intake per person of PS--campesterol, beta-sitosterol, stigmasterol, and stigmastanol--in the Spanish diet was estimated at 276 mg, the largest component being beta-sitosterol (79.7%). Other unknown compounds, tentatively identified as PS, may constitute a considerable potential intake (99 mg). When the daily PS intake among European diets was compared in terms of campesterol, beta-sitosterol, stigmasterol, and stigmastanol, the PS intake in the Spanish diet was in the same range of other countries such as Finland (15.7% higher) or The Netherlands (equal). However, some qualitative differences in the PS sources were detected, that is, the predominant brown bread and vegetable fat consumption in the northern diets versus the white bread and vegetable oil consumption in the Spanish diet. These differences may help to provide a link between the consumption of PS and healthy effects of the diet.

A method for profiling gangliosides in animal tissues using electrospray ionization–tandem mass spectrometry

Gangliosides are critical in many functions of mammalian cells but present as a minor lipid component with many molecular species of subtle differences. Conventional strategies for profiling gangliosides suffer from poor reproducibility, low sensitivity, and low-throughput capacity. Prior separation of gangliosides by thin-layer chromatography and/or high-performance liquid chromatography not only was laborious and tedious but also could introduce uneven losses of molecular species. We developed a new strategy of using electrospray ionization–tandem mass spectrometry (ESI–MS/MS) to profile gangliosides with high-throughput potential. This strategy involves three new findings: (i) collision-induced fragmentation of gangliosides gave rise to a common ion of m/ z 290, a derivative of N-acetylneuraminic acid; (ii) phospholipids exert a profound suppression of ganglioside detection in ESI–MS/MS to prevent a direct detection in total cellular lipid extracts; and (iii) enrichment of gangliosides in the aqueous phase from total cellular lipid extracts eliminates the damping effect of phospholipids and permits direct precursor scan.

Correlating the solubility behavior of minor lipid components in supercritical carbon dioxide

Isolation of minor lipid components from complex lipid mixtures is receiving increased attention due to their biological activity and health benefits. Therefore, properties, health benefits and processing aspects of minor bioactive lipid components were reviewed. Literature solubility data of binary mixtures of minor lipid components (β-carotene, α-tocopherol, stigmasterol and squalene) and supercritical carbon dioxide (SCCO 2) were correlated using Chrastil’s equation to determine the general trends of solubility behavior as affected by operating conditions and solute properties. Model parameters were estimated for the whole temperature range ( a, b, k) and at each temperature ( b′, k′). The slopes of solubility isotherms ( k′) were in the range of 4.9–10.6 for β-carotene, 4.5–9.6 for α-tocopherol, 4.9–8.0 for stigmasterol and 7.3–7.6 for squalene. Estimated model parameters were used to compare solubility behavior of these solutes with components of olein glyceride series (oleic acid and triolein) as representatives of major lipid classes found in fats and oils. The findings provide the basis for the study of multicomponent lipid mixtures. Differences in the solubility behavior of components and the effect of operating conditions on solubility can be exploited for fractionation of these multicomponent mixtures to isolate the bioactive minor lipid components.

Morphological, gravimetric, and biochemical changes in Crepidula fecunda (Gastropoda: Calyptraeidae) egg capsule walls during embryonic development

Walls of egg capsules of the gastropod Crepidula fecunda Gallardo, 1979 were examined at different developmental stages during the period of intracapsular development of embryos. The weight, biochemical composition, and structural features (using scanning and transmission electron microscopy) of the capsule walls were examined at several intervals during development of the embryos to the hatching stage. Biochemical analyses were also carried out on the intracapsular fluid to identify the possible transfer of organic material from the capsule wall to the intracapsular fluid. The capsule wall is composed principally of organic matter, primarily protein (91%), plus minor lipid and carbohydrate components. The capsule wall consists of a thin, fibrous external layer, which overlies a thicker, spongy inner layer. The spongy layer has almost disappeared by the end of the developmental period, losing about 90% of its thickness. The 40% loss in weight of the capsule walls over the developmental period is due to loss of organic matter as protein. This suggests that the inner layer of the capsules dissolves and/or disintegrates as larval development advances. The levels of dissolved and/or particulate proteins in the intracapsular fluid are much higher than those typical of the seawater surrounding the capsules. This suggests that, as embryonic development proceeds, the inner capsule walls could potentially provide extra nutrients to the embryos.

Milk fat synthesis and secretion: molecular and cellular aspects

Fatty acids esterified into triacylglycerol (TAG) by mammary epithelial cells (MEC) of lactating animals are derived either from plasma lipid or by de novo biosynthesis from small molecule precursors. The major contribution to milk lipid from plasma arises by hydrolysis of the TAG components of VLDL and chylomicrons, catalysed by lipoprotein lipase (LPL) in the mammary capillary bed; a minor contribution may come from the direct uptake of plasma non-esterified fatty acids. In the mammary gland of ruminant animals, short and medium-chain saturated fatty acids are the major products of de novo lipogenesis whereas plasma lipids contribute longer-chain and mono-unsaturated species. Human populations consuming diets disproportionately rich in saturated fatty acids experience increased risk of atherosclerosis — this association is most probably causal. Conversely, the potential health benefits associated with minor lipid components of milk fat — in particular CLA — have also recently been highlighted. This presentation will focus on selected key enzyme reactions with potential to determine and/or influence the fatty acid composition of milk lipid: ACC, SCD and FAT. Recent advances in their enzymology and molecular biology will be reviewed, emphasizing those properties that are relevant to the regulation both of their catalytic activities and of their expression. The cell biology of lipid secretion by MEC will be examined. Mammary cell/tissue models of lipid secretion will be surveyed to assess their suitability as experimental platforms for monitoring the possible effectiveness of interventions aimed at altering the amount or composition of lipid output during lactation.

Effects of minor lipids on crystallization of milk fat‐cocoa butter blends and bloom formation in chocolate

AbstractMinor lipids, such as diacylglycerols, monoacylglycerols, cholesterol, and phospholipids play a key role in crystallization of fats. In this study, the effects of minor lipid components on crystallization of blends of cocoa butter (CB) with 10% milk fat or milk‐fat fractions, and on bloom formation of chocolate were investigated. Both removing the minor lipids from milk fat and doubling the level of minor lipids from milk fat resulted in longer nucleation onset time, slower crystallization rate, and rapid bloom development in chocolate. Removal of minor lipids resulted in the formation of irregular primary and secondary crystals with inclusions of liquid fat, whereas the crystals were spherical and uniform in shape in the presence of minor lipids. Minor lipids from milk fat, even at the low concentrations typically found in nature, affected the crystallization of milk fat‐CB blends, impacted the chocolate microstructure, and affected bloom development in chocolate.

Molecular mobility in the monolayers of foam films stabilized by porcine lung surfactant

Certain physical properties of a range of foam film types that are believed to exist in vivo in the lung have been investigated. The contribution of different lung surfactant components found in porcine lung surfactant to molecular surface diffusion in the plane of foam films has been investigated for the first time. The influence of the type and thickness of black foam films, temperature, electrolyte concentration, and extract composition on surface diffusion has been studied using the fluorescence recovery after photobleaching technique. Fluorescent phospholipid probe molecules in foam films stabilized by porcine lung surfactant samples or their hydrophobic extracts consisting of surfactant lipids and hydrophobic lung surfactant proteins, SP-B and SP-C, exhibited more rapid diffusion than observed in films of its principal lipid component alone, L-alpha-phosphatidylcholine dipalmitoyl. This effect appears to be due to contributions from minor lipid components present in the total surfactant lipid extracts. The minor lipid components influence the surface diffusion in foam films both by their negative charge and by lowering the phase transition temperature of lung surfactant samples. In contrast, the presence of high concentrations of the hydrophillic surfactant protein A (SP-A) and non-lung-surfactant proteins in the sample reduced the diffusion coefficient (D) of the lipid analog in the adsorbed layer of the films. Hysteresis behavior of D was observed during temperature cycling, with the cooling curve lying above the heating curve. However, in cases where some surface molecular aggregation and surface heterogeneity were observed during cooling, the films became more rigid and molecules at the interfaces became immobilized. The thickness, size, capillary pressure, configuration, and composition of foam films of lung surfactant prepared in vitro support their investigation as realistic structural analogs of the surface films that exist in vivo in the lung. Compared to other models currently in use, foam films provide new opportunities for studying the properties and function of physiologically important alveolar surface films.

Role of palmitic acid on the isolation and properties of halorhodopsin

Purified halorhodopsin was isolated from Halobacterium halobium as previously vescribed (Duschl, A. et al. (1988) J. Biol. Chem. 263, 17016–17022). Two purple bands were eluted from phenyl-Sepharose column, indicating the presence of differently retained halorhodopsin forms; the absorption spectra of the two halorhodopsin bands in the dark were not different. By gas chromatography/mass spectrometry we could iventify palmitate (which is only a minor lipid component of archaeal cells) among lipids associated with purple fractions. Typically the palmitate content of the first eluted band was higher than that of the second, indicating a correlation between the palmitate content and the retention time; from one to two fatty acid molecules per halorhodopsin molecule were present vepending on the fraction analysed. Very little or no palmitate was released from venaturated halorhodopsin. By adding palmitate to buffers used in the phenyl-Sepharose chromatography, only one sharp purple band was collected, corresponding to the less retained halorhodopsin fraction. Pentavecanoic fatty acid could also affect the halorhodopsin chromatography. Chromatography of halorhodopsin in the presence of β-mercaptoethanol showed only one band, corresponding to the more retained halorhodopsin form. The two halorhodopsin fractions had different photoreactivity; the less retained halorhodopsin fraction (at higher palmitate content) showed an higher rate of vecay of the absorbance at 570 nm upon illumination. By following the vecay of the absorbance at 570 nm upon addition of alkali in the dark, we found that the two halorhodopsin fractions had different p K a values of veprotonation.

Analysis of soybean lecithins and beef phospholipids by HPLC with an evaporative light scattering detector

Linear (r > 0.99) calibration curves were obtained for 10–150 µg of phosphatidylethanolamine (PE), 10–75 µg of phosphaditylinositol (PI), phosphaditylserine (PS) and lysophosphatidylethanolamine, 10–100 µg of phosphatidic acid (PA) and 10–250 µg of phosphatidylcholine (PC) by high‐performance liquid chromatography analyses with an evaporative light scattering detector, a Zorbax 7‐µm silica column and gradient elution with two solvents. One solvent (A) contained 415 mL isooctane (IOCT), 5 mL tetrahydrofuran (THF), 446 mL isopropanol (IPA), 104 mL CHCl3 and 30 mL H2O; and the other solvent (B) contained 216 mL IOCT, 4 mL THF, 546 mL IPA, 154 mL CHCl3 and 80 mL H2O. The gradient in which 100% A linearly changed to 100% B in 20 min followed by 12 min of 100% B and then a linear change to 100% A during 5 min separated PE, PS and PC in soybean lecithins and beef lipids, but failed to resolve PI and PA. In these same samples, less polar lipids were separated from phospholipids (PL) by elution from Bond‐Elut silica columns with diethyl ether/hexane (20:80, vol/vol), and PL were recovered by elution with methanol. This procedure is useful for concentration of minor lipid components. Levels of PE, PI‐PA, PS and PC were higher in granular than in liquid lecithin, and PC was the most abundant PL in soybean lecithins and beef lipids.

Polar Lipid and Fatty Acid Composition of Strains of Thermus ruber

Eighteen strains of Thermus ruber from widely separated geographical areas were examined for polar lipid patterns and fatty acid composition. Five high-temperature strains of the genus Thermus were also compared. All strains related to T. ruber had two prominent glycolipids migrating very close to each other and one major phospholipid. Minor polar lipid components were found in trace amounts or appeared to be absent. With the exception of isolate VI-R1, all other red-pigmented strains had iso -C15 as the major fatty acid, followed by lower relative proportions anteiso -C15, iso -C17 and anteiso -C17 fatty acids. These results reinforce the view that T. ruber is a very homogeneous taxon.

The effect of salinity on the phase behaviour of total lipid extracts and binary mixtures of the major phospholipids isolated from a moderately halophilic eubacterium

The effects of molar NaCl concentrations on the phase behaviour of the total lipid extracts and binary mixtures of the major phospholipids, namely phosphatidylethanolamine (PE) and phosphatidylglycerol (PG), isolated from the moderately halophilic eubacterium, Vibrio costicola, grown in 1 M and 3 M NaCl containing media have been studied using X-ray diffraction and freeze-fracture electron microscopy. The effect of both the PE/PG ratio and alterations in fatty acid composition were examined by using binary mixtures which mimicked the PE/PG ratio found in the native bacterial membranes. We show that the samples exhibited complex phase behaviour, including the formation of non-bilayer phases, which depend upon the salinity of both the bacterial culture medium and the suspending solution. The total lipid from bacteria cultured in 1 M NaCl-containing medium and dispersed in 1 M NaCl exhibited a mixture of L α and hexagonal-II phases at the optimum growth temperature of the organism (i.e., 30°C), whereas the same lipid dispersed in 3 M NaCl showed only a hexagonal-II phase down to a temperature of +3°C. The total lipid extracted from 3 M NaCl cultures showed only lamellar phases over the temperature range studied (+50°C to −50°C), but the phase transition temperatures of the various lamellar phases were generally higher when the lipid was dispersed in 3 M compared with 1 M NaCl. The phase behaviour of the binary mixtures was similar but not identical to that of the corresponding total lipid extracts and it is suggested that the minor lipid components (diphosphatidylglycerol, lysophosphatidylethanolamine and lysophosphatidylglycerol) play a part in determining the phase behaviour of the native membranes. These results show that the PE/PG ratio and fatty acid composition of the individual phospholipids, which are normally regulated by Vibrio costicola in vivo in response to culture medium salinity, are both important in maintaining a stable bilayer structure within the membrane.

Effect of smoking on the lipid composition of lung lining fluid and relationship between immunostimulatory lipids, inflammatory cells and foamy macrophages in extrinsic allergic alveolitis

Normal lung lining fluid suppresses lymphoproliferative responses. This effect is mediated by the major phospholipid components, but minor lipid components can stimulate lymphocyte proliferation. The aim of this study was to discover whether the changes in lung lipid composition reported in patients with extrinsic allergic alveolitis (EAA) might influence the levels of lymphocytes which occur in the lungs of these patients. Since cigarette smokers are less susceptible to EAA, we also investigated the effect of smoking on the lipid composition of lung lining fluid. Lung lining fluid was sampled by bronchoalveolar lavage (BAL) from 15 patients with EAA, and 9 non-smokers and 13 smokers without lung disease. The smoking controls had increases in phosphatidylethanolamine, sphingomyelin and phosphatidylglycerol, but lower levels of cholesterol and cholesterol:total phospholipid ratios compared with the nonsmoking controls. By contrast, the patients with EAA had increases in total phospholipid and sphingomyelin; there were no smoking related decreases in cholesterol; and several patients had levels of cholesterol and cholesterol:total phospholipid ratios above the upper limit for the controls. In the BAL fluids of the EAA patients, the levels.ml-1 of the immunostimulatory lipids sphingomyelin, phosphatidylethanolamine, cholesterol and cholesterol esters correlated with the number.ml-1 of lymphocytes, mast cells, neutrophils and "foamy" macrophages. Cholesterol levels (rs = 0.82) and lymphocyte counts (rs = 0.90) correlated most closely with "foamy" macrophages (p less than 0.001), suggesting that uptake of cholesterol by macrophages may enhance antigen-presenting function. These observations provide some support for the hypothesis that inflammatory reactions in the lungs might be influenced by the local lipid environment.

Atherosclerotic Yucatan microswine: An animalmodel with high-grade, fibrocalcific, nonfatty lesions suitable for testing catheter-based interventions

A new breed of swine, the Yucatan microswine, that was derived from repetitive inbreeding of selected, small Yucatan swine, was investigated as an animal model of advanced vascular atherosclerosis. Nineteen animals were fed an atherogenic diet for 9.9 +/- 1.5 (mean +/- SEM) weeks before and 19.9 +/- 1.8 weeks after balloon endothelial denudation of all four iliac arteries. In 18 (94.7%) of the 19 microswine, angiography performed at 33 to 87 weeks of age disclosed some degree of luminal diameter narrowing: six animals (33.3%) had one-vessel, six (33.3%) had two-vessel, four (22.2%) had three-vessel, and two (11.1%) had four-vessel disease. In 38 (50%) of 76 denuded arteries, angiographically apparent luminal diameter narrowing was observed as follows: three arteries (7.9%) were narrowed less than 50%; 10 arteries (26.3%) were narrowed 50% to 75%; seven arteries (18.4%) were narrowed 76% to 99%; and 18 arteries (47.3%) were occluded. Sixty-four arteries were harvested from 16 of the 18 microswine with angiographically apparent luminal narrowing, which yielded 748 histologic sections. Maximum cross-sectional area narrowing from atherosclerotic plaque exceeded 90% in 135 (18%) of the sections examined, while 65 sections (9%) were narrowed 76% to 90%, and 127 sections (17%) were narrowed 51% to 75%. Atherosclerotic plaque in these animals appeared histologically similar to the so-called "complex" lesion that is typical of human atherosclerosis, which consists predominantly of collagen with focal calcific deposits and a minor lipid component. The smaller size and lower weight of these animals, in comparison with full-size farm pigs and "minipigs," facilitated transportation, handling, and instrumentation. These findings establish the Yucatan microswine as a useful, representative, and economical atherosclerotic animal model for the evaluation of novel interventional techniques.

A fatty acid methyl ester (FAMES) analyzer

AbstractFatty acids, as their methyl esters (FAMES), are routinely analyzed from a wide variety of plant and animal tissues and fluids. Samples have mainly been analyzed to date using capillary GC with FID detection. However, FID detection is non‐specific, and open to misinterpretation. This is particularly important in the analysis of minor lipid components from, e.g. organ tissues, plasma and other body fluids, where non‐FAMES impurities or contaminants can be present in relatively high amounts. This suggests that even for routine work, a mass spectral detector is necessary for the unambiguous identification–or rather, recognition–of FAMES. The FAMES analyzer we propose consists of three components: an automatic injector; a medium polarity, high‐temperature stable capillary column; a mass spectrometric detector, in our case the Finnigan–MAT ion trap detector (ITD 800). Here, on‐column injection allowed controlled sample transfer even for low absolute concentrations of lipids, and a column effluent splitter gave simultaneous qualititative and quantitative analysis. For automatic routine analysis, a mass spectral library routine using a tailor‐made library of FAMES spectra of the most common naturally occurring fatty acids, plays an essential role. Library comparison parameters used in the standard ITD software usually give “first hit” recognition over a wide sample dynamic range (ca. 2 pg to > 200 ng in the best cases). This gives an absolute recognition even of minor lipid components, especially when combined information from mass spectra and GC retention data is used. By analogy with the now well known concept of the Amino Acid Analyzer, we propose the system described as a FAMES Analyzer. Mass spectrometers like the Finnigan MAT ITD 800 are inexpensive, reliable, sensitive, and easy to operate. Unlike the Amino Acid Analyzer, the FAMES Analyzer needs the specific detection offered by mass spectrometry because the number of acids to be analyzed, including isomers, is much greater.

Release of PI-anchoring enzymes and other effects of phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis on TN-368 cells from a moth ovary

H. Ikezawa, A. Hashimoto, R. Taguchi, T. Nakabayashi and M. Himeno. Release of PI-anchoring enzymes and other effects of phosphatidylinositol-specific phospholipase C from Bacillus thuringiensis on TN-368 cells from a moth ovary. Toxicon 27, 637–645, 1989.—The effect of phosphatidylinositol-specific phospholipase C(PIPLC) from Bacillus thuringiensis was investigated on TN-368 cells, derived from the ovary of a moth, Trichoplusia ni. Quantitative analysis of lipids showed that phosphatidylinositol (PI) was contained as one of the major phospholipids in TN-368 cells, whereas sphingomyelin and cholesterol were minor lipid components. When TN-368 cells were treated with PIPLC, significant amounts of alkaline phosphatase, 5′-nucleotidase and β-glucosidase were released from these cells. Thus, these enzymes were shown to be PI-anchoring proteins in the plasma membrane of these cells. In the presence of 4.2 units of PIPLC, the cell growth of TN-368 was inhibited by 50%. In contrast with normal cells, the cells cultured in the presence of PIPLC became swollen and globular, losing their protoplasmic extensions. Also, there was degeneration of the interior of TN-368 cells cultivated in the presence of PIPLC. Mitochondria became swollen with a decrease in number of granules while the crista turned transparent. Also, an increase in lysosomes was observed and vacuoles seemingly derived from smooth endoplasmic reticula appeared.

Effect of Excess Dietary Iron on Lipid Composition of Calf Liver, Heart, and Skeletal Muscle

Effect of excess dietary iron on lipid composition of calf liver, skeletal muscle, and heart was assessed. High dietary iron (5000 versus 100ppm in milk replacer DM) had no effect on the relative proportion of lipid classes in liver or their unsaturated fatty acid composition. In muscle some minor lipid components were reduced and cholesterol and sphingomyelin increased. Excessive iron had a marked effect, however, on heart lipid composition, reducing total lipids and almost all lipid classes; triglycerides, sphingomyelin, and lysophosphatidylcholine were increased. Characteristically, sphingomyelin increases in cell membranes in response to aging and numerous pathological conditions. High dietary iron reduced linolenic acid in phosphatidylethanolamine and phosphatidylcholine of both skeletal and cardiac muscle. This may have resulted from iron-caused ethane production from autoxidation of linolenic acid or other n-3 family fatty acids, an effect known to occur in the rat. Linoleic and arachidonic fatty acids appeared to be unaffected. Plasmalogens in muscle and heart phosphatidylethanolamine and phosphatidylcholine were increased by high iron intake. As these alk-1-enyl ethers protect cells from oxidation and radiation damage, their synthesis may have been increased in response to stress from excessive iron. The results indicate that a relatively high concentration of vitamin E may be required in calf milk replacer when excessive iron is present.

Characterization of the seed and leaf lipids of high and low linolenic acid flax genotypes

The total seed lipids of four flax ( Linum usitatissimum) genotypes, differing markedly in their acyl composition, were extracted and fractionated using column, preparative, and thin-layer chromatography. In the total lipid extract of seeds, the lower linolenate content of the cultivar Glenelg (39.1% compared to that of cv. Croxton (50.5%) was associated with a higher oleate content. Further reductions in linolenate content in the induced mutants of cv. Glenelg, M1722 (17.2%) and “Zero” (1.9%) were accompanied by equivalent increases in linoleate but only minor increases in oleate. Similar changes were observed in the major triacylglycerol fraction of the simple lipids (fatty acid esters of glycerol and sterols), but there was considerable heterogeneity for acyl composition in the minor simple lipid components, including both diacylglycerols and sterol esters, and the complex lipids (glycolipids and phospholipids). The induced mutations substantially reduced linolenate content of all lipid fractions but in no case was it eliminated. Maturation of “Zero” seed at 15 10 ° C (compared to 24 19 ° C ) increased linoleate and decreased stearate and oleate contents in all lipid fractions. In contrast to seed lipids, the acyl composition of the leaf lipids of the mutant genotypes was the same as those of their parent.

1- O-Alkyl-2-acetyl- sn-glyceryl-3-phosphorylcholine (PAF) is a minor lipid component in Tetrahymena pyriformis cells

The protozoan Tetrahymena pyriformis contains 4.2 ± 2.2 ng PAF/10 7 cells. Only 1–3% of this lipid is released in the cell free medium. PAF production is not influenced by different extracellular Ca 2+ concentrations. Cell stimulation with calcium ionophore A23187 or zymosan particles does not affect the amount of PAF either. This is the first report of a natural occurrence of PAF in a protozoan.

Isolation and characterization of rabbit lung lamellar bodies.

A method has been devised for the isolation of a highly purified preparation of lamellar bodies from rabbit lung. The purity of the preparation was confirmed by electron microscopy, marker enzymes, phospholipid composition, and isopycnic centrifugation on continuous density sucrose gradients. Contamination of the lamellar bodies by such subcellular components as mitochondria, nuclei, lysosomes and plasma membranes could be excluded; however, reduced nicotinamide adenine dinucleotide phosphate (NADPH) cytochrome c reductase, an enzyme specific for the endoplasmic reticulum components was a persistent contaminant in the preparation of the isolated lamellar bodies. When the lamellar bodies were subject to isopycnic centrifugation, all of the NADPH cytochrome c reductase activity was associated with the lamellar bodies in the low density peak; no reductase activity could be detected in the region of the density gradient demonstrated to localize microsomes. Use of 3H-radiolabeled microsomes confirmed that all of the NADPH cytochrome c reductase activity present in the lamellar body preparations could be accounted for by microsomal contamination. When lamellar bodies or liposomal membranes synthesized from the total phospholipid fraction of lamellar bodies were analyzed by the electron paramagnetic resonance probe, 5-dioxyl-methylstearate, they exhibited a high degree of fluidity at physiological temperature. This was in contrast to the low fluidity of liposomal membranes composed of pure dipalmitoylphosphatidylcholine, the major component (50%) of rabbit lamellar body phospholipids. Furthermore, the major temperature-dependent phase transition in lamellar body membranes occurred at a different temperature (30.5 degrees C) from that of dipalmitoyl-phosphatidylcholine (41.0 degrees C). It is clear, therefore, that the membrane fluidity of lamellar bodies must be highly influenced by the minor lipid component.

Divergent Selection for Body Weight and Yolk Precursor in Coturnix coturnix japonica: 2. Correlated Responses in Plasma Lipoproteins and Lipids

Lipoproteins from generations five and six of Japanese quail (Coturnix coturnix japonica) divergently selected for increased (HW) or decreased (LW) body weight at 4 weeks of age or increased (HP) or decreased (LP) plasma yolk precursor at the initiation of egg production were separated into fractions of d<1.006 and d>1.006. A randombred control (R1) was also sampled. Total lipids (TL), neutral lipids (NL), and phospholipids (PL) were determined. The NL's of the d<1.006 lipoprotein fractions were also analyzed for cholesterol esters (CE), triglycerides (TG), cholesterol (C), and a fraction of minor lipid components including digycerides (DG+). A correlation of .960 between total plasma phosphorus and TL of the d<1.006 lipoprotein fraction was observed. No strain effect was note d for TL, NL, or PL for either generation in the d>1.006 fraction. In the d<1.006 fraction, TL, NL, and PL all varied concurrently, with the order being HP > HW, LW, R1> LP. Percent NL and PL did not vary with strain in the S5 generation in the d<1.006 fraction. In the S6, the HP strain had a higher % NL and lower % PL in the d<1.006 fraction. No differences in % NL and PL were noted for the d>1.006 fraction. In the d<1.006 fraction all lipid classes in the NL's tended to vary together.It was concluded that selecting for total plasma phosphorus in laying female Japanese quail is effective in quantitatively but not qualitatively altering the d <1.006 lipoprotein levels in the laying hen plasma, without affecting the d>1.006 lipoprotein levels. It was also concluded that selecting for body weight for six generations did not affect laying female lipoprotein concentration.