Fatty acid and lipid compositions of Conidiobolus

The fatty acid composition of the total lipids from two Conidiobolus species was studied by gas—liquid chromatography. The major fatty acids of C. lamprauges were palmitic acid (C_16:0), oleic acid (C_18:1), linolenic acid (C_18:3), and arachidonic acid (C_20:4). For C. eurymitus , myristic acid (C_14:0), C_16:0, and linoleic acid (C_18:2) were the most abundant acids. The fatty acid composition of C. eurymitus was quite different from that of the Conidiobolus species as mentioned in other reports. The lipid composition of the total lipids of C. lamprauges and C. eurymitus was also studied by thinchrography on quartz rods. Triglycerides and phospholipids were the major components in the two Conidiobolus species.     

Effect of short-chain fatty acids on the ethylene pathway in embryonic axes of Cicer arietinum during germination

The effect of short-chain saturated fatty acids (C₅–C₁₀) on the biosynthesis of ethylene in embryonic axes of chick-pea ( Cicer arietinum L.) seeds was investigated. The emergence of radicle and fresh weight of embryonic axes diminished with increasing number of carbons. The inhibition of germination caused by lower concentrations (1 m M ) of fatty acids (C₅–C₁₀) was partially reversed by exogenous 1-aminocyclopropane-1-carboxylic acid (ACC), whereas exogenous ethylene was able to overcome the inhibitory effect provoked by all concentrations (1–5 m M ) of applied fatty acids (C₅–C₁₀). Ethylene production rates, and enzyme activities of ACC synthase and ACC oxidase decreased concomitantly with the molecular mass and increasing concentration of fatty acids. The inhibitory effect of these acids on ethylene production seems to result not only from a decreased ACC synthesis, but also from an enhancement of 1-malonylamino)cyclopropane-1-carboxylic acid (MACC) synthesis.     

Cellular fatty acid composition in moderately halophilic Gram-negative rods

The fatty acid compositions for 40 strains of moderately halophilic Gram-negative rods were determined by gas-liquid chromatography. The strains studied were included in the genera: Vibrio, Deleya, Alteromonas, Chromobacterium, Flavobac-terium and Pseudomonas. Although there were quantitative differences all strains showed more or less similar spectra of fatty acids ranging from C₁₂ to C₂₀ chain. The major fatty acid species were C_16:0, C_16:1 and C_18:1. Most striking was the predominance of the C_18:1 component, the major fatty acid in extracts of 29 of the 40 strains.     

Arabidopsis CER8 encodes LONG-CHAIN ACYL-COA SYNTHETASE 1 (LACS1) that has overlapping functions with LACS2 in plant wax and cutin synthesis

Plant cuticle is an extracellular lipid-based matrix of cutin and waxes, which covers aerial organs and protects them from many forms of environmental stress. We report here the characterization of CER8 / LACS1 , one of nine Arabidopsis long-chain acyl-CoA synthetases thought to activate acyl chains. Mutations in LACS1 reduced the amount of wax in all chemical classes on the stem and leaf, except in the very long-chain fatty acid (VLCFA) class wherein acids longer than 24 carbons (C₂₄) were elevated more than 155%. The C₁₆ cutin monomers on lacs1 were reduced by 37% and 22%, whereas the C₁₈ monomers were increased by 28% and 20% on stem and leaf, respectively. Amounts of wax and cutin on a lacs1-1 lacs2-3 double mutant were much lower than on either parent, and lacs1-1 lacs2-3 had much higher cuticular permeability than either parent. These additive effects indicate that LACS1 and LACS2 have overlapping functions in both wax and cutin synthesis. We demonstrated that LACS1 has synthetase activity for VLCFAs C₂₀–C₃₀, with highest activity for C₃₀ acids. LACS1 thus appears to function as a very long-chain acyl-CoA synthetase in wax metabolism. Since C₁₆ but not C₁₈ cutin monomers are reduced in lacs1 , and C₁₆ acids are the next most preferred acid (behind C₃₀) by LACS1 in our assays, LACS1 also appears to be important for the incorporation of C₁₆ monomers into cutin polyester. As such, LACS1 defines a functionally novel acyl-CoA synthetase that preferentially modifies both VLCFAs for wax synthesis and long-chain (C₁₆) fatty acids for cutin synthesis.     

Effect of non-target cells on the sensitivity of the PCR for Escherichia coli O157 : H7

The fatty acid composition from mycelia of Streptomyces hygroscopicus strains was studied. A significant proportion of C_{18 : 2} was found in cultures. High levels of C_{16 : 0}, iso-C_{16 : 0} and C_{18 : 1} were also detected in all S. hygroscopicus strains. The different representatives of S. hygroscopicus had almost the same proportion of unsaturated fatty acids. Certain shifts in the amount of iso, anteiso and straight-chain fatty acids in some cultures were revealed. This might be explained by the adaptation capability of strains belonging to one species to form a variety of available fatty acids determined by particular cell membrane composition favouring certain antibiotic biosynthesis.     

Myelin Gangliosides: An Unusual Pattern in the Avian Central Nervous System

Abstract: Gangliosides were isolated from purified myelin obtained from brain and spinal cord of mature chickens and pigeons. Total concentrations were approximately two- to fivefold greater than for previously reported mammalian species, and their patterns also differed in containing significantly more sialosylgalactosylceramide (G_M4). The latter comprised one-third to one-fourth of total myelin ganglioside, approximately equivalent to G_M1 (II³NeuNAc-GgOse₄Cer). As in mammals, G_M4 of avian CNS appeared to be localized in myelin. Fatty acids of this ganglioside included both the hydroxy- and unsubstituted types. and, long-chain bases were almost entirely C₁₈. Ganglioside G_M1 split into two closely migrating bands on TLC, the slower of which resembled mammalian G_M1 in having stearate as the main fatty acid with a measurable amount (10%) of C₂₀-sphingosine; the faster band had predominantly longer-chain fatty acids and very little C₂₀-sphingosine.     

Phototrophic growth on n-fatty acids by species of the genus Rhodocyclus sensu Imhoff et al.

Abstract Type strains of Rhodocyclus purpureus, R. gelatinosus and R. tenuis along with three local isolates of R. gelatinosus were tested for growth in the light on n -fatty acids ranging in chain length from C₅ (valerate) to C₂₂ (docosanoate).
R. purpureus , the type species of the genus, was anomalous in its limited ability to grow on n -fatty acids; no fatty acids of chain length greater than C₉ (nonanoate) were utilized. R. gelatinosus and R. tenuis , on the other hand, utilized all fatty acids in the range C₅ to C₁₈ inclusive. R. gelatinosus showed some restricted ability to use C₂₀ (eicosanoate) and C₂₂ (docosanoate) fatty acids.     

GANGLIOSIDES OF HUMAN MYELIN: SIALOSYLGALACTOSYLCERAMIDE (G7) AS A MAJOR COMPONENT

Abstract— Gangliosides were isolated from purified human myelin in a yield of 62 μg of lipid-bound sialic acid per 100 mg of dry myelin. Sialosylgalactosyl ceramide (G₇) was found to be a major component of the ganglioside fraction, amounting to 15 per cent of the total sialic acid. It accounted for 10 per cent of lipid-bound sialic acid in adult human white matter, making it the third most abundant ganglioside on a molar basis. These results were obtained with an improved method for isolating total gangliosides in high yield, by employing DEAE-Sephadex column chromatography. Myelin from other mammalian species had considerably less G₇, and there were also indications of maturational changes. Both 2-hydroxy and unsubstituted fatty acids were components of the ceramide unit, in a ratio of 3:2, respectively. The overall fatty acid pattern was very similar to that for myelin cerebroside and sulphatide. Long-chain bases included only C₁₈ species, with sphingosine predominating (>90 per cent). These observations suggest a metabolic relationship between G₇ and either cerebroside or sulphatide.     

PELIZAEUS-MERZBACHER DISEASE: BRAIN LIPID AND FATTY ACID COMPOSITION

Abstract— Biochemical analysis of the leukodystrophy brain from a case of Pelizaeus-Merzbacher disease, classical type, was performed. A decrease in the amount of solid material present was found. The lyophilized brain weight was reduced to 76% of normal with a slightly greater decrease in the amount of extractable lipid. Total myelin was diminished to 7% of normal. Among specific lipids plasmalogens were present in slightly lowered amounts. Cerebrosides and sulphatides were drastically reduced to 8% of normal, whereas sphingomyelin was less severely affected. Fatty acids from phospholipids were close to normal, only enols being slightly diminished. Analysis of pure cerebrosides and sulphatides revealed that the a-hydroxylated compounds as well as very long chain fatty acids (over C₁₈, especially C₂₃ to C₂₆) were greatly reduced. For chain lengths over C₁₈, the ratio of leukodystrophy fatty acid to normal fatty acid was close to 10%. The defect in very long chain fatty acids is estimated at 99.2% in total brain.
Thus, we have found a marked decrease in the amount of very long chain fatty acids and a less marked decrease in sphingolipids. The reduced amount of these acids appears to be partially offset by an increase in the amount of medium-chain fatty acids in sphingolipids. We conclude that one aspect of Pelizaeus-Merzbacher disease may be a defect in the synthesis of myelin very long chain fatty acids (as these acids are far much reduced than any other myelin molecule).     

Effect of growth temperature and salt concentration on the fatty acid composition of Flavobacterium halmephilum CCM2831

Abstract In this study the fatty acid composition of Flavobacterium halmephilum CCM2831 grown at different temperatures and salt concentrations is reported. At elevated growth temperatures the amount of cellular saturated long-chain acids (C_18:0 and C_20:0) and the branched-chain acid br-C_17:0 increased, and the concentrations of both cyclic acids and the branched chain acid br-C_15:0 decreased. Increasing the salt concentration in the medium resulted in a gradual increase in cellular cyclopropanoic acids and a concomitant decrease in the monounsaturated fatty acid content.     

LIPID CLASS DISTRIBUTION OF HIGHLY UNSATURATED LONG CHAIN FATTY ACIDS IN MARINE DINOFLAGELLATES

The very long chain highly unsaturated C₂₈ fatty acids, octacosaheptaenoic [28:7(n-6)] and octacosaoctaenoic acid [28:8(n-3)], were found to be associated with phospholipids, obtained by fractionation of total lipid extracts into distinct lipid classes, in 4 and 6, respectively, of 16 examined dinoflagellates. An interfraction comparison of fatty acids associated with phospholipids and glycolipids has also shown that the phospholipid fractions contained the majority (over 75% in 12 of 16 strains) of docosahexaenoic acid [22:6(n-3)] and traces of tetracosanoic acid (24:0). By contrast, the highly unsaturated C₁₈ fatty acids octadecatetraenoic [18:4(n-3)] and octadecapentaenoic acid [18:5(n-3)] were primarily recovered from a chloroplast-associated glycolipid fraction comprised of monogalactosyldiacylglycerol, digalactosyldiacylglycerol, and sulfoquinovosyldiacylglycerol. In 12 of 16 strains, an interfraction comparison showed that over 90% of 18:5(n-3) was found to be associated with glycolipids. These findings indicate that the C₂₈ fatty acids are located and probably synthesized in the cytoplasm or in an organelle other than the chloroplast, possibly with 22:6(n-3) and 24:0 as precursors, whereas the C₁₈ fatty acids 18:4(n-3) and 18:5(n-3) are glycolipid constituents apparently synthesized within the chloroplast. The function(s) of these C₂₈ fatty acids as components of phospholipids in cellular membranes is currently unknown.     

Uptake and utilization of n-octacosane and n-nonacosane by Arthrobacter nicotianae KCC B35

Arthrobacter nicotianae KCC B35 isolated from blue-green mats densely covering oil sediments along the Arabian Gulf coast grew well on C₁₀ to C₄₀ n -alkanes as sole sources of carbon and energy. Growth on C₂₀ to C₄₀ alkanes was even better than on C₁₀ to C₁₈ alkanes. Biomass samples incubated for 6 h with n -octacosane (C₂₈) or n -nonacosane (C₂₉) accumulated these compounds as the predominant constituent alkanes of the cell hydrocarbon fractions. The even chain hexadecane C₁₆ and the odd chain pentadecane C₁₅ were the second dominant constituent alkanes in C₂₈ and C₂₉ incubated cells, respectively. n -Hexadecane-incubated cells accumulated in their lipids higher proportions of C₁₆-fatty acids than control cells not incubated with hydrocarbons. On the other hand, C₂₈ and C₂₉-incubated cells did not contain any fatty acids with the equivalent chain lengths, but the fatty acid patterns of the cell lipids suggest that there should have been mid-chain oxidation of these very long chain alkanes. This activity qualifies A. nicotianae KCC B35 to be used in cocktails for bioremediating environments polluted with heavy oil sediments.     

FATTY ACID COMPOSITION OF CEREBROSIDES, SULPHATIDES AND CERAMIDES IN MURINE LEUCODYSTROPHY: THE QUAKING MUTANT

Abstract— The fatty acid composition of cerebrosides, sulphatides and ceramides has been determined at 20 days postpartum in the brains of Quaking mutant mice and of littermate controls. There was a significant deficit in the proportion of long-chain fatty acids (C₂₂-C₂₄) affecting both normal and a-hydroxy fatty acids of the cerebrosides. The proportion of normal but not the a-hydroxy long-chain fatty acids of the sulphatides was also decreased. Striking and disproportionate deficits of the C_24:1 and C_{24 h:1} fatty acids of cerebrosides, sulphatides and ceramides characterized the brain of the Quaking mutant, and an increased proportion of C_{23 h:O} fatty acid was found in the cerebrosides and sulphatides of the brain of this mutant. We compared these data with findings on the Jimpy mutant which has been examined by the same techniques. The deficiency of long-chain fatty acids which was found in the cerebrosides and sulphatides of both mutants was less extensive but more selective in the Quaking mutant.     

Carbon isotope-labelling experiments indicate that ladderane lipids of anammox bacteria are synthesized by a previously undescribed, novel pathway

Ladderane lipids are unusual membrane lipids of bacteria that anaerobically oxidize ammonium to dinitrogen gas (anammox). Ladderane lipids contain linearly concatenated cyclobutane rings for which the pathway of biosynthesis is currently unknown. To investigate the possible biosynthetic routes of these lipids, 2-¹³C-labelled acetate was added to a culture of the anammox bacterium Candidatus Brocadia fulgida. Labelling patterns obtained by high-field ¹³C nuclear magnetic resonance spectroscopy of isolated lipids indicated that C . Brocadia fulgida synthesizes C_16:0 and iso C_16:0 fatty acids according to the known pathway of type II fatty acid biosynthesis. The ¹³C-labelling pattern of the C₈ alkyl chain of the C₂₀ [3] ladderane monoether also indicated the use of this route. However, carbon atoms in the cyclobutane rings and the cyclohexane ring were nonspecifically labelled and did not correspond to known patterns of fatty acid synthesis. Taken together, our results indicate that it is unlikely that ladderane lipids are formed from the cyclization of polyunsaturated fatty acids as hypothesized previously and suggest an alternative, although as yet unknown, pathway of biosynthesis.     

Polar lipid ester-linked fatty acid composition of Lake Vechten seston: an ecological application of lipid analysis

Abstract In order to relate the benthic lipid composition to possible sources in the water column, the sestonic communities of a monomictic lake were profiled using their saponifiable polar lipid fatty acids, which were identified by capillary gas chromatography-mass spectrometry (GC-MS). The epilimnion, dominated by the dinoflagellate alga Ceratium hirundella , was characterized by C_20:5 and C_22:6 polyunsaturated fatty acids. The photic anoxic metalimnion supported a radically different community, dominated by photosynthetic sulfur-oxidizing bacteria ( Chromatium and Chloronema spp.) and a Synechococcus -like cyanobacterium, and was characterized by high concentrations of C₁₆ and C₁₈ monounsaturated fatty acids. The fatty acid compositions of the hypolimnetic seston and the sediment were qualitatively similar to that of the metalimnion. Methyl-branched acids, commonly found in eubacteria, increased with depth in the water column. The concentrations of several unusual fatty acids found in Desulfovibrio spp. Desulfobacter spp. and Desulfotomaculum spp. were inversely related to sulfate concentration in the metalimnion. After the water column mixed in the winter, steep gradients of respiratory terminal electron acceptors developed in the surface sediment and were reflected in the polar lipid fatty acid compositions. The results show that fatty acids derived from the membranes of epilimnetic phytoplankton were efficiently metabolized in the oxic portion of the water column. The fatty acids synthesized by prokaryotic microorganisms at and below the oxycline dominated the sediment. The polar lipid fatty acid composition of the sediment showed seasonal changes which can be associated with concentrations of terminal electron acceptors of microbial respiration, and thus with physiologically distinct bacterial groups.     

Temperature-dependent changes in phospholipid and fatty acid composition and membrane lipid fluidity of Yersinia enterocolitica

Temperature-dependent compositional changes of phospholipids and their fatty acids were analysed in Yersinia enterocolitica grown at 5°, 25° and 37°C. The relative amounts of the four phospholipids, phosphatidylethanolamine (75–78%), phosphatidylglycerol (10–11%), cardiolipin (<7%) and lysophosphatidylethanolamine (<5%), were essentially the same at all growth temperatures. The degree of fatty acid unsaturation of the four phospholipids increased with decrease in growth temperature, mainly due to an increase of C_16:1 and C_18:1 and a corresponding decrease of C_16;0, C_18:0 and cyclo C_17:0. An electron spin resonance spectroscopic study of the membrane lipids showed that membrane lipid fluidity was enhanced by decreasing the growth temperatures. The changes in fatty acid composition of phospholipids in response to varied temperatures were consistent with the temperature-dependent changes in the membrane lipid fluidity of Y. enterocolitica , and were similar to those reported for other bacteria.     

Two pathways of sphingolipid biosynthesis are separated in the yeast Pichia pastoris

Although the yeast Saccharomyces cerevisiae has only one sphingolipid class with a head group based on phosphoinositol, the yeast Pichia pastoris as well as many other fungi have a second class, glucosylceramide, which has a glucose head group. These two sphingolipid classes are in addition distinguished by a characteristic structure of their ceramide backbones. Here, we investigate the mechanisms controlling substrate entry into the glucosylceramide branch of the pathway. By a combination of enzymatic in vitro studies and lipid analysis of genetically engineered yeast strains, we show that the ceramide synthase Bar1p occupies a key branching point in sphingolipid biosynthesis in P. pastoris. By preferring dihydroxy sphingoid bases and C(16)/C(18) acyl-coenzyme A as substrates, Bar1p produces a structurally well defined group of ceramide species, which is the exclusive precursor for glucosylceramide biosynthesis. Correlating with the absence of glucosylceramide in this yeast, a gene encoding Bar1p is missing in S. cerevisiae. We could not successfully investigate the second ceramide synthase in P. pastoris that is orthologous to S. cerevisiae Lag1p/Lac1p. By analyzing the ceramide and glucosylceramide species in a collection of P. pastoris knock-out strains in which individual genes encoding enzymes involved in glucosylceramide biosynthesis were systematically deleted, we show that the ceramide species produced by Bar1p have to be modified by two additional enzymes, sphingolipid Δ4-desaturase and fatty acid α-hydroxylase, before the final addition of the glucose head group by the glucosylceramide synthase. Together, this set of four enzymes specifically defines the pathway leading to glucosylceramide biosynthesis.     

Lipid and pigment composition of a chlorophyll b-deficient mutant of Chlamydomonas reinhardii

Lipids and pigments of the chlorophyll b -deficient mutant pg-113 and the parent strain (ps) of Chlamydomonas were analysed and compared. Monogalactosyldiglyceride, digalactosyldiglyceride, diacylglyceryl(N, N, N-trimethyl)homoserine, sulfoquinovosyldiglyceride, phosphatidylglycerol, phosphatidylethanolamine, phosphatidylinositol were found as major lipid components. While the lipid patterns were qualitatively and quantitatively almost the same in the two strains, the C₁₆/C₁₈ fatty acid ratios were different, 0.85 in the mutant and 1.11 in the parent strain. Furthermore, the relative amounts of C₁₆- and C₁₈-monoene fatty acids were slightly enhanced and the C₁₈-trienes slightly reduced in the mutant. In the parent strain, chlorophylls a and b , α- and β-carotene, lutein, violaxanthin, neoxanthin and loroxanthin were detected by HPLC. In the mutant, similar pigments were found, except that only traces of chlorophyll b and a reduced amount of neoxanthin were present. Since no chlorophyll-protein complex CP II could be detected in the mutant by electrophoresis, the possible interrelationships between pigment deficiency and alteration of chlorophyllprotein complexes are discussed.     

Lipid Investigation of Central and Peripheral Nervous System in Connatal Pelizaeus-Merzbacher's Disease

Abstract: Brain grey and white matter of a case of Pelizaeus-Merzbacher disease (connatal type Seitelberger) of a 19-month-old boy were analysed with respect to lipids. Cerebrosides and sulfatides were totally absent in the pathological brain. In comparison to control, differences in gangliosides could be detected in grey and white manner. C_18:1, fatty acids were markedly reduced in the main glycerophospholipids of white matter. In sphingomyelin of cortex and white matter 90% of fatty acids were C_18:0; longer chains were absent. In contrast: PNS (nervus fernoralis) lipids contained the main galactolipids. However, these a s well as all other lipid classes showed a 20% reduction compared with values obtained from nervus femoralis of an infant of the same age. The fatty acid patterns of all lipid classes were determined. The only marked deviations from normal were observed in the C₂₄-chains of cere-brosides and sulfatides. The formalin-fixed brain of an older brother (same disease) was analysed only with respect to glycolipids: neither cerebrosides nor sulfatides could be detected.