Seasonal changes in the content of lipids,fatty acids,and pigments in brown alga <Emphasis Type="Italic">Costaria costata</Emphasis>

We compared the content of total lipids, particular lipid classes, fatty acids (FAs), and pigments in the brown alga Costaria costata [Turn.] Saund (Laminariaceae) in different seasons: during algal active life (April–June) and in the beginning of their degradation (the end of July). Lipids comprised only a small part of algal extractable compounds (10.9–13.4%). Their higher content was observed in May, in the period of alga preparation to sporogenesis. Polar lipids, glyceroglycolipids (GL) and phospholipids (PL), comprised a great part of total lipids in spring months and June, whereas neutral lipids, in July. GL predominated in polar lipids in spring and summer. The highest content of GL was observed in May and PL in April. Storage lipids comprised a great part of lipids in July. The content of sterols was the highest in April and May. In summer months, the content of sterols decreased and remained on unchanged level until thallus degradation. Polyunsaturated FAs (PUFAs) comprised the most part of FAs. Their highest content was observed in April. The main part of PUFAs were those of ω-3 series. In July, the level of these PUFA decreased substantially. The levels of ω-6 PUFAs were approximately similar in spring and summer months. The lowest content of monounsaturated FAs was detected in April; in May and July; the relative content of these FAs increased sharply. We also detected seasonal changes in the content of pigments and the ratios between them.     

Lipid Composition of Tomato Leaves as Related to Plant Cold Tolerance

We studied the effects of a low nonlethal temperature (6°C) on the content and composition of polar lipids and their fatty acids in tomato (Lycopersicon esculentum Mill., cv. Sibirskie skorospelye) leaves. We demonstrated that chilling resulted in a decrease in the content of total polar lipids per 1 mg protein. The content of lipids in chloroplast membranes (monogalactosyldiacylglycerols, digalactosyldiacylglycerols, sulfoquinovosyldiacylglycerols, and phosphatidylglycerols) changed less substantially than the content of phospholipids in other cell organelles and in the cytoplasm. Neutral lipids comprised only 1% of total lipids, and their content also decreased after chilling. The relative amounts of unsaturated and saturated fatty acids in polar lipids were practically unchanged. The conclusion was drawn that the maintenance of a high level of chloroplast membrane lipids under low temperatures could play an important role in the survival of cold-tolerant plants.     

Indentification and Localization of the Fatty Acids in Haemophilus parainfluenzae

Haemophilus parainfluenzae was capable of synthesizing 22 fatty acids. These fatty acids were equivalent to 4% of the bacterial dry weight. These fatty acids were localized in the membrane-wall complex, which contained the respiratory pigments, the quinone, and the phospholipids. The fatty acids which could be extracted with organic solvents comprised 86% of the total fatty acids of the cell. These fatty acids were distributed as 98% in the phospholipids and 1.9% in the neutral lipids, of which 0.5% were free fatty acids. Palmitic, palmitoleic, oleic, and vaccenic acids comprised 72% of the total fatty acids and were found almost exclusively in the phospholipids. The phospholipids also contained the cyclopropane fatty acids. The neutral lipids contained significant proportions of the odd-numbered branched and straight-chain fatty acids. The principal free fatty acids were n-dodecanoic and pentadecenoic acids. The nonextractable wall complex contained 14% of the total fatty acids. These wall fatty acids were rendered soluble only after saponification. The wall fraction contained all of the beta-hydroxymyristic acid and most of the myristoleic and pentadecenoic acids. The significance of the distribution of fatty acids between nonesterified, neutral lipid, phospholipid, and nonextractible wall remains to be determined.     

Production of algae-based biodiesel using the continuous catalytic Mcgyan® process

This study demonstrates the production of algal biodiesel from Dunaliella tertiolecta, Nannochloropsis oculata, wild freshwater microalgae, and macroalgae lipids using a highly efficient continuous catalytic process. The heterogeneous catalytic process uses supercritical methanol and porous titania microspheres in a fixed bed reactor to catalyze the simultaneous transesterification and esterification of triacylglycerides and free fatty acids, respectively, to fatty acid methyl esters (biodiesel). Triacylglycerides and free fatty acids were converted to alkyl esters with up to 85% efficiency as measured by 300 MHz ¹H NMR spectroscopy. The lipid composition of the different algae was studied gravimetrically and by gas chromatography. The analysis showed that even though total lipids comprised upwards of 19% of algal dry weight the saponifiable lipids, and resulting biodiesel, comprised only 1% of dry weight. Thus highlighting the need to determine the triacylglyceride and free fatty acid content when considering microalgae for biodiesel production.     

Lipid Composition and Localization of 10-Methyl Branched-chain Fatty Acids in Corynebacterium simplex Grown on n-Alkanes

1. Corynebacterium simplex ATCC 6946 grown on a n-alkane mixture (C₁₄-C₁₆) contained 13% of total lipids, which composed of approximately equal quantities of neutral lipids and compound lipids. Phospholipids, corresponding to about 60% of compound lipids, comprised phosphatidylinositol mannoside and cardiolipin as the major components, and phosphatidylglycerol and phosphatidylethanolamine as the minor components.

2. When this bacterium was cultivated on n-octadecane in the presence of cobaltous ion, a large amount of tuberculostearic acid (10-methylstearic acid) was synthesized, which was exclusively localized in phosphatidylinositol mannoside and was not detected in neutral lipids.     

Lipid profile of the halophilic alga,Dunaliella salina

The lipid composition comprised more than 50% of the cellular organic material. Greater than 30% of the total lipid composition consisted of hydrocarbons. The aliphatic hydrocarbons consisted of C-17 and C-19 saturated and unsaturated ones, some of them with an internal methyl branch. The remaining lipids consisted of a large quantity of pigmented hydrocarbons together with at least six sterol derivatives, six phospholipids, two glycolipids, one sulfolipid and numerous other components that were not fully identified. This wall-less alga is an immensely rich source of a wide variety of lipids.     

News & Notes: The Effect of Ethanol and Oxygen on the Growth of Zymomonas mobilis and the Levels of Hopanoids and Other Membrane Lipids

Zymomonas mobilis (ATCC 29191) was grown either aerobically or anaerobically in the presence of 2% (wt/vol) glucose and 0, 3, or 6% (vol/vol) ethanol. The rates of growth and the composition of hopanoids, cellular fatty acids, and other lipids in the bacterial membranes were quantitatively analyzed. The bacterium grew in the presence of 3% and 6% ethanol and was more ethanol tolerant when grown anaerobically. In the absence of ethanol, hopanoids comprised about 30% (by mass) of the total cellular lipids. Addition of ethanol to the media caused complex changes in the levels of hopanoids and other lipids. However, there was not a significant increase in any of the hopanoid lipid classes as ethanol concentration was increased. As previously reported, vaccenic acid was the most abundant fatty acid in the lipids of Z. mobilis, and its high constitutive levels were unaffected by the variations in ethanol and oxygen concentrations. A cyclopropane fatty acid accounted for 2.6–6.4 wt % of the total fatty acids in all treatments. Received: 12 November 1996 / Accepted: 25 February 1997     

Thermal behavior and lipid composition of cauliflower plasma membranes in relation to ATPase activity and chilling sensitivity

A plasma-membrane fraction rich in ion-stimulated ATPase activity was isolated from cauliflower (Brassica oleracea L.) buds. The activity of the ATPase was dependent on Mg(2+) and stimulated 4-fold by K(+). The lipids of the membrane fraction contained 57% by weight of phospholipid, 16% glycolipid including sterol glycosides, and 27% neutral lipids. Sterols and sterol esters comprised 9% by weight of the total lipid fraction, and the m ratio of total sterol to phospholipid was 0.5. Fatty acid unsaturation of the membrane lipids was 75%. Arrhenius plots of the Mg(2+) and Mg(2+) + K(+) stimulated ATPase activity were biphasic with an increase in activation energy occurring below about 12 degrees C, a response typical of some membrane-associated enzymes of chilling-sensitive plants. No thermal transitions were detected in the membranes or membrane lipids between 0 and 30 degrees C using differential scanning calorimetry and electron spin resonance spectroscopy. This type of thermal behavior is typical of membranes of chilling-resistant plants. It was concluded that the low temperature increase in activation energy of the ion-stimulated, membrane-associated ATPase is an intrinsic property of the enzyme system and not the result of a transition in the bulk membrane lipid.     

Human stratum corneum lipids: characterization and regional variations

The lipids of mammalian stratum corneum are known to be important regulators of skin permeability. Since the human stratum corneum displays remarkable regional variations in skin permeability, we assessed the total lipid concentration, the distribution of all major lipid species, and the fatty acid composition in Bligh-Dyer extracts from four skin sites (abdomen, leg, face, and sole) that are known to display widely disparate permeability. Statistically significant differences in lipid weight were found at the four sites that were inversely proportional to their known permeability. In all four sites, among the polar lipids, the stratum corneum contained negligible phospholipids, but substantially more cholesterol sulfate (1-7%) than previously appreciated. As in the stratum corneum from other mammals, the bulk of the lipids consisted of neutral (60-80%) and sphingolipids (15-35%). Of the neutral lipids, free sterols (4- to 5-times greater than esterified sterols), free fatty acids, triglycerides, and highly nonpolar species (n-alkanes and squalene) predominated. n-Alkanes, which were present in greater quantities than previously appreciated, comprised a homologous series of odd- and even-chained compounds ranging from C19 to C34. The sphingolipids comprised over 80% ceramides vs. lesser quantities of glycosphingolipids. In all four sites, the sphingolipids were the major repository of long-chain, saturated fatty acids. The neutral lipid:sphingolipid ratio generally was proportional to the known permeability of each site: higher neutral lipids and lower sphingolipids generally were associated with superior barrier properties. These studies provide: 1) the first detailed, quantitative analysis of human stratum corneum lipids and 2) information about the variability in lipid composition at four skin sites with known differences in permeability. The latter results suggest that variations in neutral lipids, rather than sphingolipids, may underlie local variations in skin permeability.     

Arachidonic and other long-chain polyunsaturated fatty acids in spermatophores and spermathecae of Teleogryllus commodus: Significance in prostaglandin-mediated reproductive behaviour

Estimates of weights of fatty acids, especially arachidonic acid, in spermathecae from virgin and mated T. commodus indicate substantial elevation in all fatty acids and particularly arachidonic acid following mating. Analysis of spermatophore lipids suggests that this can be in part accounted for by the contents of one or several spermatophores. Fractionation of total lipids from spermatophores showed that arachidonic acid comprised 24% of phosphotidylcholine and 4% of phosphotidylethanolamine, but was not detected in neutral lipids whereas it was approximately equally distributed over phosphotidylcholine and phosphotidylethanolamine in lipids from spermathecae. These data indicate that in addition to prostaglandin synthetase, the spermatophore contains a physiologically significant quantity of prostaglandin precursor, arachidonic acid, esterified to phospholipid and presumably unavailable for enzymatic action during mating transfer. We also note that proportions of arachidonic acid in the phosphotidylcholine of spermatophores are the highest recorded for this fatty acid in the insect literature, which in conjunction with recent work emphasizes the likely physiological significance of long-chain polyunsaturated fatty acids in insects generally.     

Lipid composition of a plasma membrane enriched fraction of maize roots

The lipid composition of a plasma membrane enriched fraction isolated from corn (Zea mays) roots was examined. On a wt basis, the lipid: protein ratio was 1.11. Phospholipids comprised 60% of total lipids with the major phospholipids being phosphatidylcholine (62%) and phosphatidylethanolamine (21%). Free sterol was the major neutral lipid. The sterol:phospholipid molar ratio was 0.31. The fatty acid composition of the membrane was predominantly linoleic (60%) and palmitic (30%).     

Growth-coupled lipid synthesis in Mortierella alpina LPM 301, a producer of arachidonic acid

Mortierella alpina LPM 301, a producer of arachidonic acid (ARA), was found to possess a unique property of intense lipid synthesis in the period of active mycelium growth. Under batch cultivation of this strain in glucose-containing media with potassium nitrate or urea, the bulk of lipids (28-35% of dry biomass) was produced at the end of the exponential growth phase and remained almost unaltered in the stationary phase. The ARA content of lipids comprised 42-50% at the beginning of the stationary phase and increased continuously after glucose depletion in the medium due to the turnover of intracellular fatty acids; by the end of fermentation (189-210 h), the amount of ARA reached 46-60% of the total fatty acids (16-19% of dry mycelium). Plausible regulatory mechanisms of the growth-coupled lipid synthesis in microorganisms are discussed.     

Skin reaction to lipids from avirulent strain Shibaura of Leptospira interrogans serovar copenhageni

Sonically disrupted cells from avirulent strain Shibaura of Leptospira interrogans serovar copenhageni induced a skin reaction characterized by infiltration of polymorphonuclear leukocytes (PMN) associated with some edema in guinea pigs. To determine the substance inducing infiltration of PMN, lipids of avirulent strain Shibaura were extracted with chloroform--methanol--water after washing with acetone. The lipids comprised 28% of the dry weight of the cell. When the lipids were further separated into water--methanol and chloroform fractions, the most severe PMN infiltration of all samples was seen in the skin inoculated with extract recovered from the chloroform fraction. Neutral and polar lipids were detected after thin-layer chromatography of the chloroform extract. Neutral lipids were detected as free fatty acids (FFA). Fatty acids contained in polar lipids were mainly palmitic acid and palmitoleic acid, whereas FFA comprised 66.5% oleic acid. Skin reactions consisting of marked edema with mild infiltration of PMN were elicited by FFA. There was no obvious difference between a commercially available FFA mixture and the FFA from avirulent strain Shibaura. These observations suggest that FFA may play some role in the pathogenesis of leptospirosis.     

The lipids of Agaricus bisporus.

A comparison of the lipid composition of the vegetative and reproductive stages of Agaricus bisporus revealed no major qualitative differences, although quantitative divergence exist. The glycolipids consisted of acylglucoses, acylmannitol, acyltrehalose and a glucosyloxyfatty acid. Two of the acylglucoses corresponded to a tetra-acylglucose and to either a di- or a triacylglucose. The phospholipids were distinctive in that phosphatidylcholine could not be detected. Phosphatidylethanolamine and phosphatidylserine were the major phosphoglycerides. Examination of the neutral lipids revealed the expected array of acylglycerols, free and esterified sterols, and free fatty acids. A substantial amount (26 to 33%) of the fatty acids of the neutral lipids from both sporophore and mycelium were apparently of chain length greater than C18. Linoleic acid was a minor component of the total neutral-lipid fatty acids but comprised about one-half of the total free fatty acids.     

Comparative analysis of fatty acids in pollen and seed of rapeseed

Lipids accounted for 31.7% of the dry wt of mature, viable pollen of rapeseed (Brassica napus). External lipids of the pollen coat, specified by the diploid parental genome, and internal cytoplasmic lipids, presumably specified by the haploid pollen genome, were separated by differential extraction. External lipids and paraffins represented 9.8 % of pollen dry wt, and contained predominantly linolenic (18:3) with significant amounts of palmitic (16:0), stearic (18:0) and myristic (14:0) acids, as well as paraffins. Internal lipids accounted for 21.9% of pollen dry wt and comprised predominantly 18:3 and 16:0. Mature seeds of B. napus comprised 45.0 % lipid, with a fatty acid composition different from that of either pollen fraction. Decanoic (10:0), lauric (12:0) and hexadecatrienoic (16:3) acids were detected in pollen but not in seeds. These data are discussed in relation to pollen biochemistry and the potential for pollen selection in rapeseed breeding.     

Structural analysis of glycolipids from Borrelia burgdorferi

In this study the lipids of Borrelia burgdorferi, the causative agent of Lyme disease, were analyzed. Lipids comprise about 25-30% of the cell dry weight. The lipid fraction could be separated by HPTLC into 11 components. Staining of these components revealed two glycolipids and two phospholipids. The glycolipids represented about 50% of the total lipids and comprised only galactose as monosaccharide constituents. By means of mass spectrometric and gas chromatographic analysis both glycolipids could be identified as alpha-galactosyl-diacylglycerolipids with different fatty acid compositions. The phospholipids were identified as phosphatidylcholine and phosphatidylglycerol. Immunoassays with sera from patients with Lyme disease showed antibody reactivity only to the glycolipids, which was present in all stages of the disease. Other lipid components seemed to be non-immunogenic in Lyme disease. The glycolipids of B. burgdorferi may be, thus, considered promising candidates for diagnosis and possibly also for vaccination.     

Lipid transfer particle in locust hemolymph: purification and characterization

A lipid transfer particle (LTP) from the hemolymph of adult male locusts, Locusta migratoria, was isolated and purified. The locust LTP exhibited its capacity to catalyze the exchange of diacylglycerol between low density lipophorin (LDLp) and high density lipophorin (HDLp). Contrary to the LTP reported for the tobacco hornworm, M. sexta, the locust LTP appeared to lack the capacity to promote net transfer of diacylglycerol to form an intermediate density lipophorin, although it seems premature to conclude the complete lack of such a capacity in locust LTP. The original concentration of LTP in hemolymph is assumed to be extremely low compared to that of lipophorin; only a catalytic amount of LTP may be present in the hemolymph (e.g., only 160 micrograms of LTP was obtained from the original hemolymph containing 400 mg protein). The molecular weight of intact LTP was estimated to be about 600,000 and the LTP was comprised of three glycosylated apoproteins, apoLTP-I (mol wt 310K), apoLTP-II (mol wt 89K), and apoLTP-III (mol wt 68K). The locust LTP contained significant amounts of lipids; the total lipid content amounted to 14.4% and the lipids were comprised of 17% hydrocarbons, 44% diacylglycerol, 8% cholesterol, 13% free fatty acid, and 18% phospholipids. The above molecular properties of locust LTP are essentially similar to those reported for M. sexta LTP.     

Fatty acid changes during development of zygotic and microspore-derived embryos of Brassica napus

Cultured microspores of Brassica napus L. cvs Topas and Reston initiated cell divisions within 3 to 4 days, and globular, heart and torpedo shaped embryos were prevalent after approximately 6, 8, and 10 days, respectively. Embryos with rudimentary cotyledons were evident within 2 weeks, but those that reached this stage of development represented only 1–5% of the original microspore population. The fresh weight of microspore-derived embryos at all stages of development was significantly greater than that for zygotic embryos, but the pattern of change in fresh weight and fatty acid accumulation was similar in developing zygotic and microspore embryos. In freshly isolated microspores of both Topas (low erucic acid) and Reston (high erucic acid), the predominant fatty acid was 18:3, while 18:1 comprised less than 15% of total fatty acids. During development in both zygotic and microspore embryos, the level of 18:3 declined markedly while 18:1 rapidly increased. Erucic acid (22:1) was not detected in the early stages of embryogenesis in Reston. However, small amounts of 22:1 appeared by early cotyledonary stage and the level gradually increased in both zygotic and microspore embryos through the later stages of development. The fatty acid compositions of mature embryos was nearly identical to that of dry seed, except the level of 22:1 in Reston embryos was consistently less than in the seed. Triacylglycerols comprised only 15% of total lipids in freshly isolated microspores, but increased to more than 90% by 4 weeks. The fatty acid composition of the triacylglycerol fraction was generally similar to that of total lipids at all stages of development of microspore-derived embryos.     

Interaction of the lipid and protein components of pulmonary surfactant Role of phosphatidylglycerol and calcium

We investigated the interaction of a major apolipoprotein of pulmonary surfactant with mixtures of lipids analogous to those found in natural surfactant. The apolipoprotein was extracted from canine surfactant and was purified to about 90% homogeneity. The apolipoprotein was mixed with liposomes of lipids in buffers containing 0.1 M sodium chloride and 3 mM calcium chloride at 22°C for 2 h or 37°C for 30 min. Two fractions were separated by centrifugation in sucrose density gradients at 15 000 rev./min. One was comprised of an aggregated, relatively high density recombinant lipoprotein which sedimented to a position toward the bottom of the centrifuge tube; the other remained at the top of the centrifuge tube and was mainly comprised of unbound lipid. The amount of lipid recovered as a sedimenting lipoprotein was dependent upon its composition. Those mixtures of lipids which contained dipalmitoyl phosphatidylglycerol formed sedimenting complexes which comprised 14% to 53% of the recovered lipid; those without phosphatidylglycerol formed such aggregates with less than 13% of the available lipid. Moreover, the lipid-to-protein stoichiometry of the recombinant was also dependent upon phosphatidylglycerol, and lipids containing this phospholipid displayed enhanced binding at a critical concentration of lipid which varied with temperature and composition. Calcium was required to form the sedimenting complex at 37°C. These results suggest that phosphatidylglycerol may be involved in the formation of a micelle-like complex, the stoichiometry of which is regulated over a narrow range of lipid concentration, and the structure of which involves calcium. The physiological advantage of forming this complex has not been determined. We found, however, that lipids containing phosphatidylglycerol absorbed more rapidly to an air/liquid interface than did those without. This rate of adsorption was further increased after interaction with the apolipoprotein.     

Lipid Composition of Plasma Membranes and Tonoplasts Isolated from Etiolated Seedlings of Mung Bean (Vigna radiata L.)

The lipid composition of plasma membranes and tonoplasts from etiolated mung bean hypocotyls was examined in detail. Phospholipids, sterols, and ceramide monohexoside(s) were the major lipid classes in both membranes. The content of phospholipids on a protein basis was higher in the tonoplast, but the content of total sterols was similar in both membranes. Accordingly, the sterol to phospholipid molar ratio in the plasma membrane was higher than that of the tonoplast. Phosphatidylethanolamine and phosphatidylcholine comprised the major phospholipids in both membranes. Phosphatidylinositol, phosphatidylserine, and phosphatidylglycerol were identified as minor phospholipid components. The content of phosphatidylinositol and phosphatidylglycerol was relatively high in the tonoplast, comprising 11 and 5% of the total phospholipids, respectively. Although special care was taken against the degradative action of phospholipase D and phosphatidic acid phosphatase during the isolation of these membranes, by adding EDTA, EGTA, KF, choline, and ethanolamine to the homogenizing medium, significant amounts of phosphatidic acid, about 15% of the total phospholipids, were detected in the plasma membrane. On the other hand, the content of phosphatidic acid in tonoplasts and other membrane fractions was very low. This fact may indicate that high levels of phosphatidic acid occur naturally in plasma membranes. Phosphatidylglycerol in both membranes and phosphatidylinositol in the tonoplast contained high levels of palmitic acid, which comprised more than 50% of the total fatty acids. Significant differences were observed in the sterol compositions of plasma membranes and tonoplasts. More than 90% of the sterols in the plasma membrane were unesterified, while the tonoplast was enriched in glycosylated sterols, especially acylated sterylglycosides. Ceramide monohexoside was found to be specifically located in these membranes, in particular, in the tonoplast, in which it comprised nearly 17% of the total lipids.