Lipid composition and metabolism in oospores and oospheres ofAchlya americana

Oospores and oospheres ofAchlya americana Humphrey were isolated by sonication and filtration through nylon-mesh cloth of progressively diminishing porosity, and their lipid composition was investigated. The average dry weight of an oospore was 3.2 ng. Approximately 37% of the dry weight was composed of lipid. Triacylglycerols represented 88.7% of the total lipid, unesterified fatty acids made up 9.7%, and sterols, sterol esters, phospholipids, and mono- and diacylglycerols each constituted less than 1% of the total. Palmitic, oleic, and linoleic acids were the predominant fatty acids, along with smaller amounts of myristic, palmitoleic, stearic, arachidonic, and eicosapentaenoic acids. The fatty acid composition of the triacylglycerol fraction was similar to that of the total lipid, while that of the phospholipid fraction was higher in oleic acid. The unesterified fatty acid fraction was higher in saturated components than the total lipid, while the sterol ester fraction was higher in unsaturated fatty acids. In both the total lipid and the various lipid classes, unsaturated fatty acids increased during spore development. The sterol fraction consisted of 72% fucosterol, 22% cholesterol, and 7% 24-methylenecholesterol. In both oospheres and oospores, 1-[¹⁴C] acetate was assimilated most readily into phospholipids, triacylglycerols, and unesterified fatty acids, and was incorporated preferentially into palmitic, palmitoleic, and oleic acids. 1-[¹⁴C]-Arachidonic acid was incorporated by isolated oospheres into eicosapentaenoic acid, indicating that arachidonic acid is the immediate precursor of eicosapentaenoic acid.     

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

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

Effect of sub-inhibitory concentration of chlorhexidine on lipid and sterol composition of shape Candida albicans

The effect of a sub-inhibitory concentration of chlorhexidine on lipid and sterol composition of Candida albicans was investigated. The total lipid content of this yeast grown in the presence of chlorhexidine was reduced whilst the total sterol content was increased compared with control-grown cells. Lipids and sterol analyses of this yeast grown in the presence and absence of chlorhexidine are presented. Chlorhexidine-grown yeast had a higher level of phosphatidylethanolamine, phosphatidylcholine and monogalactosyldiacylglycerol. Lower proportions of phosphatidylinositol plus phosphatidylserine, phosphatidic acid and cardiolipin were found in C. albicans grown in the presence of the drug when compared with control-grown yeast. The major fatty acids in control-grown cells were C16 and C18. Drug grown-cells had higher proportions of palmitic acid (16 : 0) and stearic acid (18 : 0), but lower proportions of palmitoleic acid (16 : 1) and oleic acid (18 : 1). Chlorhexidine also decreased the unsaturated-to-saturated fatty acid ratio, while the C16/C18 ratios increased compared to control-grown cells. Differences in the fatty acid composition of major phospholipids and neutral lipids between drug and control-grown yeast were also detected. Sterol analysis of control-grown cells showed that the major sterol present was ergosterol (55.4% wt). A significant increase in ergosterol and obtusifoliol was observed in chlorhexidine-treated cells and a significant decrease in squalene and lanosterol. Our results suggested that chlorhexidine affected the lipid and sterol composition of C. albicans. This revised version was published online in August 2006 with corrections to the Cover Date.     

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%).     

A crystalline lipid phase in a dry biological system: evidence from X-ray diffraction analysis of Typha latifolia pollen

The temperature limits for germination in Typha latifolia pollen lie within the range 4-40 degrees C. These limits correlate at the low-temperature end with the 'crystallization' of endogenous triacylglycerols and on the high-temperature end with the 'melting' of a gel-like lipid component in intact pollen. X-ray diffraction analysis was used to structurally characterize and to trace the latter gel-like lipid from the intact pollen through a range of pollen lipid fractions. We tentatively identify this component as a fatty acyl sterol ester and present evidence that it resides in the exine of the pollen grain. Its thermotropic behavior is insensitive to pollen hydration. The possibility of interpreting a crystalline lipid phase as being membrane-derived when in fact it originates from contaminating non-membranous neutral lipid is discussed. The total lipid content of T. latifolia pollen is 123 mg/g dry weight, of which 37% is polar lipid. The neutral lipid consists primarily of triacylglycerols and of the aforementioned sterol ester, which represents 0.34% (w/w) of pollen dry weight. The polar lipid fraction has phosphatidylcholine, phosphatidylethanolamine and phosphatidic acid as major components with lesser amounts of phosphatidylglycerol and phosphatidylinositol. Palmitic (16:0) and linoleic (18:2) acids, in a 1:2 molar ratio, constitute the major fatty acids of both polar and neutral lipid fractions with lesser amounts of linolenic (18:3), oleic (18:1) and stearic (18:0) acid in evidence.     

Carbohydrate and lipid components of hyphae and conidia of human pathogenFonsecaea pedrosoi

The carbohydrate and lipid components of mycelium and conidia ofFonsecaea pedrosoi (Brumpt) were analysed by paper, thin-layer and gas-chromatography, mass spectrometry and ultraviolet spectroscopy. Glucose, mannose, galactofuranose, rhamnose and glucosamine were polysaccharide components identified inF. pedrosoi. Significant changes in the carbohydrate pattern occurred during the conversion of mycelium into conidia. Rhamnose was predominant in conidia whereas galactose was prominent in mycelium. Palmitic, stearic, oleic, linoleic, and arachidonic acids were the fatty acids identified in the total lipid fraction. Palmitic and oleic acids were major fatty acids. Marked alterations in the fatty acid constituents were observed between the cell types ofF. pedrosoi. Arachidonic acid was detected only in conidia and linoleic acid was preferentially identified in mycelium. Differences in the sterol composition was also associated with morphogenesis inF. pedrosoi. Two main sterols, ergosterol and another less polar sterol, not fully characterized, were found in mycelium whereas in conidia only the latter sterol was present.     

The lipid composition and permeability to the triazole antifungal antibiotic ICI 153066 of serum-grown mycelial cultures of Candida albicans

The total lipid content of Candida albicans (serotype A: NCPF 3153) exponential-phase mycelial cultures grown in tissue-culture medium 199 (containing 10%, v/v, foetal calf serum) was 29.8 +/- 8 mg (g dry weight)-1 (mean +/- SD). The weight ratios of phospholipid to neutral lipid and phospholipid to non-esterified sterol were 2.6 +/- 0.4 and 24.9 +/- 0.5, respectively. The major phospholipid was phosphatidylcholine with smaller amounts of phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, phosphatidylglycerol and diphosphatidylglycerol; the most abundant fatty acids were palmitic, palmitoleic, oleic and linoleic acids. The major neutral lipids comprised esterified sterol, triacylglycerol and non-esterified fatty acid with a smaller amount of non-esterified sterol. The fatty acid compositions of the three fatty-acid-containing neutral lipids were distinct from each other and the phospholipids. Comparison with previous data on yeast cultures of C. albicans A grown in glucose broth shows that mycelial cultures have a larger lipid content, lower phospholipid to neutral lipid ratio and higher phospholipid to non-esterified sterol ratio. We now show that mycelial cultures were more permeable to a [14C]triazole antifungal antibiotic compared with exponentially growing yeast cultures of several azole-sensitive strains. Taken together these data are consistent with there being a relationship between the phospholipid/non-esterified sterol ratio of a culture and its ability to accumulate a triazole.     

Lipid changes of goat sperm plasma membrane during epididymal maturation

Highly purified plasma membranes of maturing goat caput-, corpus- and cauda-epididymal spermatozoa were isolated by aqueous two-phase polymer methods and their lipid constituents were analysed. Phospholipid (approx. 75% w/w), neutral lipid (approx. 15% w/w) and glycolipid (approx. 10% w/w) were the major sperm membrane lipids. There was a significant decrease in the total lipids (approx. 25% w/w), phospholipid (approx. 30% w/w) and glycolipid (approx. 80% w/w) contents of sperm membrane during epididymal maturation. On the contrary, the mature cauda-sperm membrane showed greater (approx. 50% w/w) neutral lipid content than that of the immature caput sperm. Phosphatidylcholine (PC), phosphatidylethanolamine (PE) and sphingomyelin were the phospholipids of the sperm membrane, the former two being the major lipids. Both PC and PE fractions consisted of three species--diacyl, alkylacyl and alkenylacyl forms, the last one being the dominant species in both PC and PE. Of all the phospholipids, diacyl PE decreased most strikingly (approx. 65% w/w) during sperm maturation. The neutral lipid fraction contained sterols, wax esters, 1-O-alkyl-2,3-diacylglycerol, triacylglycerol and fatty acids. Sterols represented nearly 75% w/w of the neutral lipids and cholesterol was the major component (approx. 95% w/w) of the sterol fraction. The sperm maturity was associated with marked increase of sterol (approx. 60% w/w) and steryl ester (approx. 200% w/w) and decrease (approx. 50-65% w/w) of the other membrane-bound neutral lipids. The glycolipid was identified as monogalactosyldiacylglycerol. The fatty acid profile of the various membrane lipids underwent marked alteration during the epididymal transit of the male gametes. Cholesterol/phospholipid and saturated/unsaturated fatty acid ratios increased greatly in the maturing sperm membrane. The altered lipid profile of the mature sperm membrane leads to changes in its fluidity that play an important role in determining the structure and functions of the biomembrane.     

Isolation of the plasma membrane of a trypanosomatid flagellate: General characterization and lipid composition

A technique is described for the isolation of a fraction that contains the plasma membrane of the trypanosomatid flagellate Leptomonas collosoma. This fraction has been investigated by electron microscopy and has been shown to be mostly membranes associated with microtubules, a known plasma membrane marker in this organism. The fraction is enriched in Mg²⁺-dependent ATPase but has a decreased specific activity of succinate dehydrogenase. Lipid has been extracted from whole cells and the isolated plasma membrane fraction. A fraction of the total lipid that is eluted from a silicic acid column by acetone is found to be concentrated in the plasma membrane. Also enriched in the plasma membrane fraction is a 5,7-diene sterol identified as ergosterol. The major phospholipids of the whole cell and the plasma membrane are phosphatidylethanolamine and phosphatidylcholine. Approximately 60% of the fatty acids of the cell and plasma membrane have a carbon chain length of eighteen, and half of this is in the form of the mono-unsaturated fatty acid.     

Lipid composition of maturing and elongate liverwort sporophytes

The setae of Lophocolea heterophylla sporophytes undergo rapid cell elongation with no net loss of lipid. Glycerolipids and sterol esters are the predominant lipids present in unelorigate setae. Phospho- and glycolipids increase dramatically with respect to total lipid during elongation and thus reflect membrane increases. Unusual polyunsaturated fatty acids (arachidonic and eicosapentaenoic) are conspicuous constituents of these lipids.     

Seasonal changes in the constituents of Ulva lactuca

The green marine algal species Ulva lactuca, contains appreciable amounts of lipids, but there is no correlation between the lipid content and its unsaponified fraction. The sterol content of this alga depended on the proportion of the unsaponified lipid fraction in total lipids. The presence of cholesterol-like material was demonstrated. The algal material was characterized by a high content of rhamnose (28%) in April and glucuronic acid (15·74%) in February. Variations were also found in the patterns of free amino acids and of those of the isolated algal protein. A milk-clotting factor was detected in the water extract of the algal material.     

Regulation of glucose and lipid metabolism in health and disease

Glucose and fatty acids are the major sources of energy for human body. Cholesterol, the most abundant sterol in mammals, is a key component of cell membranes although it does not generate ATP. The metabolisms of glucose, fatty acids and cholesterol are often intertwined and regulated. For example, glucose can be converted to fatty acids and cholesterol through de novo lipid biosynthesis pathways. Excessive lipids are secreted in lipoproteins or stored in lipid droplets. The metabolites of glucose and lipids are dynamically transported intercellularly and intracellularly, and then converted to other molecules in specific compartments. The disorders of glucose and lipid metabolism result in severe diseases including cardiovascular disease, diabetes and fatty liver. This review summarizes the major metabolic aspects of glucose and lipid, and their regulations in the context of physiology and diseases.     

Lipid composition of plasma membranes from barley leaves and roots, spinach leaves and cauliflower inflorescences

Highly purified plasma membranes (PM) were obtained from barley (Hordeum vulgare L. cv. Kristina) leaves and roots, spinach (Spinacia oleracea L. cv. Viking II) leaves, and cauliflower (Brassica oleracea) inflorescences by partitioning in an aqueous polymer two-phase system. The sterol and polar lipid composition of the PM, including the fatty acid composition of the glycerolipids, was determined. Dominating lipids were free sterols, glucocerebroside, phosphatidylcholine (PC) and phosphatidylethanolamine (PE), although large variations in content were observed between the PM of the different species and organs. Thus, the spinach leaf PM contained only 7% (mol %) free sterol compared to over 30% free sterol in the other PM analysed, with the barley root PM as the other extreme (57% free sterol). On the other hand, sterol derivatives were more abundant in the spinach leaf PM, containing 13% acylated sterol glycosides. Cerebroside constituted 16% of the lipids in the barley leaf PM but only 3% in cauliflower. The phospholipids PC and PE ranged from 25 and 24%, respectively, in the spinach leaf PM to 8 and 7%, respectively, in the barley root PM. As a result of the large variations in sterol and phospholipid content, the ratio of free sterol to phospholipid varied from 2.2 in the barley root PM to only 0.1 in the spinach leaf PM. Sitosterol, campesterol and stigmasterol were the completely dominating sterols in the barley and cauliflower PM, whereas the unique sterol composition of spinach was dominated by spinasterol. Palmitic (16:0), linoleic (18:2) and linolenic (18:3) acid were the major glycerolipid fatty acids. The fatty acid composition of the barley root PM was the most saturated (44% 16:0, 13% 18:3), whereas that of the cauliflower PM was the most unsaturated (21% 16:0,42% 18:3). Thus, very large variations were observed in both total lipid and fatty acid composition of the PM investigated, which represent both mono— and dicotyledons, as well as both photosynthetic and non-photosynthetic tissue. The consequences of this large diversity in composition of the lipid bilayer for the function of integral PM proteins are discussed.     

Seasonal variations in sterol composition of Delesseria sanguinea (Ceramiales,Rhodophyta)

On Normandy coasts, the red alga Delesseria sanguinea perennates by its stipe; fronds grow in January and disappear in June. Seasonal variations in sterol composition in relation to the biology of D. sanguinea are reported. Sterols in cellular membranes are free or conjugated by esterification with fatty acids, heterosides or lipid complexes like phospholipids. Both kinds of sterols were analyzed by GC-MS. The major sterol (80%) found in fronds was cholesterol whereas in stipes, cholesterol was also the major sterol in spring, but in September, an important reduction in cholesterol yield was noted with proportional increase in sitosterol content. It appears that cholesterol is synthesized in fronds in spring, then transferred to the stipe, which loses an important amount of cholesterol with loss of the blades.     

The lipids of phosphorescent Vibrio albensis bacteria]

The lipid composition of fluorescent vibrios, V. eltor and nonagglutinating vibrios has been studied. In the fraction of polar lipids phosphatidylethanolamine, phosphatidylinositol and cardiolipin and in the fraction of neutral lipids monoglycerides, free fatty acids, diglycerides, triglycerides, sterol esters have been identified. The fatty acid composition of some classes of neutral lipids have been determined. Both similarity and differences between the strains under study in their lipid and fatty acid composition have been established.     

Presence and synthesis of cholesterol in stable staphylococcal L-forms.

The sterol which was present in two strains of a stable staphylococcal L-form was analyzed by gas-liquid chromatography and combined gas-liquid chromatography-mass spectrometry. The retention time of the sterol on gas-liquid chromatography was the same as that of authentic cholesterol. Analysis of the sterol by mass spectrometry showed a molecular ion at an m/e of 386 and the same patterns of major ions above an m/e of 145 as those of authentic cholesterol. As a result, the sterol in staphylococcal L-form was identified as cholesterol. A parent strain and its L-forms were cultured in medium containing [14C]acetate, and the synthesis of cholesterol was examined. In the L-forms, 0.52% of the total lipid radioactivity was found in cholesterol fraction, whereas no significant radioactivity was detected in the cholesterol fraction of the parent strain, indicating that staphylococcal L-forms have acquired the capacity to synthesize cholesterol.     

Effects of the hypocholesteremic agent trifluperidol on the sterol, steryl ester, and fatty acid metabolism of Saccharomyces cerevisiae.

Trifluperidol (TFP), at a concentration of 100 muM, inhibited the 24-h growth of Saccharomyces cerevisiae by about 30%. Effects on lipid metabolism were investigated by monitoring the incorporation of [1-14C]sodium acetate into various lipid fractions after 4 and 24 h of growth in the presence of several concentrations of TFP. Although little effect was noted on the amount of free sterols, 24-h incorporation of label into steryl esters was increased two- to fourfold by 100 muM TFP. Major sterol components of the steryl ester fraction isolated from an untreated culture were zymosterol (48%) and ergosterol (24%), whereas from the TFP-treated culture delta8,24(28)-ergostadienol (66.6%) and delta8-ergostenol (14.7%) were most abundant. Free sterols present in the highest concentration in the untreated culture were ergosterol (78.2%) and lanosterol (13%); whereas delta8,22-ergostadienol (38.5%), delta8-ergostenol (35.4%), and delta8,24(28)-ergostadienol (25.4%) were the most abundant free sterols obtained from the TFP-treated culture. Thus, the major block in the sterol biosynthetic pathway in yeast appears to be delta8 leads to delta7 isomerization. In these same cultures the relative amounts of C12 and C14 acids isolated from both steryl ester and miscellaneous lipid fractions were increased more than threefold over controls.     

Changes in lipid composition of Blumeria graminis f.sp. tritici conidia produced on wheat leaves treated with heptanoyl salicylic acid

Treatment of wheat leaves with heptanoyl salicylic acid (HS) and trehalose at concentrations of 0.1 and 15 g l(-1), prior to fungal inoculation, resulted in 40% and 60% protection, respectively, against powdery mildew. The total lipid composition of Blumeria graminis f.sp. tritici (Bgt) conidia, the causal agent of wheat powdery mildew, was compared when produced on wheat leaves, respectively, untreated and treated with the two elicitors, HS and trehalose. An obvious effect was observed on lipid composition (sterol and fatty acid (FA)) of Bgt conidia produced on wheat leaves treated with HS. A total of 16 FA (C12-C24 saturated and unsaturated) as well as unusual methoxylated Fatty Acids (mFA) (3-methoxydocosanoic and 3-methoxytetracosanoic acids) were detected in the conidia. Medium chain FA were predominant in HS treated conidia (64.65%) while long chain fatty acids constituted the major compounds in untreated conidia (62%). The long chain/medium chain FA ratio decreased from 1.8 in the conidia produced on untreated leaves to 0.5 in the conidia obtained from HS treated leaves. When comparing the sterol composition of Bgt conidia produced on leaves treated with HS versus conidia obtained from untreated ones, very important changes within the two major classes can be seen. In particular, 24-methylsterols, e.g., 24-methylenecholesterol and 24-methylcholesta-7,24-dien were reduced by about 82% whereas 24-ethylsterols, e.g., 24-ethylcholesterol and 24-ethylcholesta-5,22-dienol were increased by about 85%. The 24-methylsterols/24-ethylsterols ratio was reduced by ninefold in the conidia produced from HS treated leaves.     

Evidence for a Composite State of an F′his,gnd Element and a Cryptic Plasmid in a Derivative of Salmonella typhimurium LT2

The zoospores of Blastocladiella emersonii, when derived from cultures grown on solid media, contain about 11% total lipid. This lipid was separated chromatographically on silicic acid into neutral lipid (46.6%), glycolipid (15.8%), and phospholipid (37.6%). Each class was fractionated further on columns of silicic acid, Florisil, or diethylaminoethyl-cellulose, and monitored by thin-layer chromatography. Triglycerides were the major neutral lipids, mono- and diglycosyldiglycerides were the major glycolipids, and phosphatidylcholine and phosphatidylethanolamine were the major phospholipids. Other neutral lipids and phospholipids detected were: hydrocarbons, free fatty acids, free sterols, sterol esters, diglycerides, monoglycerides, lysophosphatidylcholine, lysophosphatidylethanolamine, phosphatidic acid, phosphatidylserine, and phosphatidylinositol. Palmitic, palmitoleic, stearic, oleic, gamma-linolenic, and arachidonic acids were the most frequently occurring fatty acids. When B. emersonii was grown in (14)C-labeled liquid media, lipid again accounted for 11% of both mature plants and zoospores released from them. The composition of the lipid extracted from such plants and spores was also the same; however, it differed markedly from that of the lipid in spores harvested from solid media, consisting of 28.3% neutral lipid, 12.0% glycolipid, and 59.7% phospholipid. The major lipids were again triglycerides for neutral lipids, mono- and diglycosyldiglycerides for glycolipids, and phosphatidyl choline and phosphatidylethanolamine for phospholipids.     

LIPID COMPOSITION OF CHLORARACHNIOPHYTES (CHLORARACHNIOPHYCEAE) FROM THE GENERA BIGELOWIELLA,GYMNOCHLORA, AND LOTHARELLA1

The Chlorarachniophyceae are unicellular eukaryotic algae characterized by an amoeboid morphology that may be the result of secondary endosymbiosis of a green alga by a nonphotosynthetic amoeba or amoeboflagellate. Whereas much is known about the phylogeny of chlorarachniophytes, little is known about their physiology, particularly that of their lipids. In an initial effort to characterize the lipids of this algal class, four organisms from three genera were examined for their fatty acid and sterol composition. Fatty acids from lipid fractions containing chloroplast‐associated glycolipids, storage triglycerides, and cytoplasmic membrane‐associated polar lipids were characterized. Glycolipid‐associated fatty acids were of limited composition, principally eicosapentaenoic acid [20:5(n‐3)] and hexadecanoic acid (16:0). Triglyceride‐associated fatty acids, although minor, were found to be similar in composition. The polar lipid fraction was dominated by lipids that did not contain phosphorus and had a more variable fatty acid composition with 16:0 and docosapentaenoic acid [22:5(n‐3)] dominant along with a number of minor C₁₈ and C₂₀ fatty acids. Crinosterol and one of the epimeric pair poriferasterol/stigmasterol were the sole sterols. Several genes required for synthesis of these sterols were computationally identified in Bigelowiella natans Moestrup. One sterol biosynthesis gene showed the greatest similarity to SMT1 of the green alga, Chlamydomonas reinhardtii. However, homologues to other species, mostly green plant species, were also found. Further, the method used for identification suggested that the sequences were transferred to a genetic compartment other than the likely original location, the nucleomorph nucleus.