The effect of low temperature on fatty acid composition and tocopherols of the red microalga, <Emphasis Type="Italic">Porphyridium cruentum</Emphasis>

Porphyridium cruentum was grown in 10 L batch culture at 18°C, pH 8.0 and 28‰ salinity. The cells were harvested in the stationary phase and the fatty acid composition analysed by GC and tocopherol content by HPLC. A total of 14 fatty acids were identified including saturated fatty acids (13:0, 14:0, 14:0 iso, 15:0, 16:0, 16:0iso) and monounsaturated fatty acids (MUFAs; 16:1(n-7), 18:1(n-7), 18:1(n-9). Polyunsaturated fatty acids (PUFAs) were the predominant fatty acids detected, reaching 43.7% of total fatty acids in the stationary phase of culture. Among the PUFAs, eicosapentaenoic acid (EPA, 20:5(n-3)) was dominant (25.4%), followed by 12.8% arachidonic acid (AA, 20:4(n-6)). α-Tocopherol and γ-tocopherol contents were 55.2 μg g⁻¹ dry weight and 51.3 μg g⁻¹ dry weight respectively.     

Effect of Exogenous Fatty Acids on the Cellular Fatty Acid Composition and Neomycin Formation in a Mutant Strain of Streptomyces fradiae

A mutant of Streptomyces fradiae which requires oleic acid for neomycin formation was isolated and the effects of exogenous fatty acids and other additives on the formation of neomycin were studied. Palmitic acid and high concentration of sodium ions could replace oleic acid in neomycin formation. The fatty acid spectrum of the mutant strain ST–5B was quite different from that of the parent strain 3123. The major fatty acid components of the mutant and the parent were anteiso 15:0 and iso 16: 0, respectively. However the fatty acid composition of the mutant was changed from the anteiso 15: 0-type to the parental iso 16: 0-type by the supplement of oleic acid or high concentration of sodium ions in the medium. In the case of palmitic acid, the major fatty acid component of the mutant cells was changed from anteriso 15: 0 to normal 16:0. The role of these additives in neomycin formation by the mutant is discussed.     

Changes in fatty acids composition,hydrogen peroxide generation and lipid peroxidation of salt-stressed corn (<Emphasis Type="Italic">Zea mays</Emphasis> L.) roots

Comparative study about the salt-induced oxidative stress and lipid composition has been realised in primary root tissues for two varieties of maize (Zea mays L.) in order to evaluate their responses to salt stress. The root growth, root water content (WC), hydrogen peroxide (H₂O₂) generation, lipid peroxidation, membrane stability index and the changes in the profile of fatty acids composition were investigated. Salinity impacts in term of root growth, water content, H₂O₂ generation, lipid peroxidation and membrane destabilisation were more pronounced in primary roots of Aristo than in those of Arper indicating more sensitivity of the first variety. It was confirmed by gas chromatography that the composition of fatty acids in roots of both varieties was constituted mainly by 16:0 and 18:0 as major saturated fatty acids and 18:1ω9, 18:2ω6 and 18:3ω3 as major unsaturated fatty acids. Total lipid extracts from the roots of both varieties showed that the lipid saturation level increased under salt stress, notwithstanding the increased proportion of polyunsaturated fatty acids. The changes in lipid saturation being predominantly due to decreases in oleic acid (18:1ω9) and increases in palmitic acid (16:0). However, Arper root extracts contained a lower proportion of saturated lipids than Aristo. The enhanced proportion of highly polyunsaturated fatty acids especially linolenic and eicosapentaenoic acids was considered to be the characteristic of the relatively salt tolerance in Arper roots.     

Alterations in growth temperature range and fatty acid composition of Thermus as a result of plasmid elimination

Elimination of plasmids from Thermus flavus, T. thermophilus and three wild Thermus strains caused alterations in growth temperature range, pigmentation and membrane fatty acids without affecting viability. Following plasmid elimination all Thermus strains lost their ability to grow above 70°C. In addition, the minimum growth temperature was lowered by 5–10°C. Fatty acids were reduced by an average of approximately 35%. In addition, the contribution of iso- and anteisobranched fatty acids were altered in four of the five strains. The iso C_15:0/iso C_17:0 ratio approached 1.0 in all strains, whereas the anteiso C_15:0/anteiso C_17:0 was reduced to 0.2. The iso C_16:0/normal-C_16:0 ratio increased in all strains due to an increase in iso C_16:0 in four strains and a reduction in normal-C_16:0 relative to iso C_16:0 in one strain. However, it was evident that the plasmid-free strains were able to compensate for these alterations in membrane fluidity to a certain extent by reducing the average chain length of isobranched acids. Altered fatty acid metabolism at the level of precursors may have influenced membrane composition and consequently growth temperature range.     

Potential role of antioxidants during ethanol-induced changes in the fatty acid composition and arachidonic acid metabolites in male Wistar rats

Biochemical assessment of liver damage during ethanol-induced stress was done by measuring the activities of serum enzymes, viz., aspartate transaminase (AST) and alkaline phosphatase (ALP), which were significantly elevated in rats fed ethanol. Ethanol administration for a period of 60 days modifies the fatty acid composition, and the analysis of fatty acids showed that there was a significant increase in the concentrations of palmitic acid (16:0), stearic acid (18:0), and oleic acid (18:1) in liver, kidney, and brain, whereas the concentrations of palmitoleic (16:1) and arachidonic acid (20:4) were significantly decreased. The breakdown products of arachidonic acids (20:4), prostaglandins, were elevated. The antioxidants curcumin and N-acetylcysteine (NAC) decreased the activities of serum AST and ALP. Curcumin and NAC decreased the concentrations of fatty acids, viz., palmitic, stearic, and oleic acid, whereas arachidonic acid and palmitoleic acid were elevated. The prostaglandin concentrations were also decreased after curcumin and N-acetylcysteine treatment. Thus the present investigation shows that curcumin and N-acetylcysteine prevent the fatty acid changes produced by ethanol and also reduce the inflammatory response of ethanol by reducing the level of prostaglandins. This revised version was published online in July 2006 with corrections to the Cover Date.     

Roots volatiles and fatty acids of coriander (<Emphasis Type="Italic">Coriandrum sativum</Emphasis> L.) grown in saline medium

An hydroponic culture was conducted to investigate the effect of saline stress on the essential oil and fatty acid composition of Tunisian coriander (Coriandrum sativum L.) roots. Ten days old coriander seedlings were treated during 3 weeks with different NaCl concentrations (0, 25, 50 and 75 mM). Roots volatile components and fatty acids were analyzed. The essential oil yield was 0.06% in the control, on the basis of dry matter weight, and did not changed at low concentration (25 mM), while it increased significantly with increasing NaCl concentrations to reach 0.12 and 0.21% at 50 and 75 mM NaCl, respectively. The major volatile component was (E)-2-dodecenal with 52% of total essential oil constituents, followed by decanal, dodecanal, (E)-2-tridecenal and (E)-2-dodecenal. Further, the amount of these compounds was affected differently by the NaCl level. Total fatty acid amount of coriander roots increased significantly only with 50 and 75 mM NaCl. Three major fatty acids: linoleic (43%), oleic (25.5%) and palmitic (21.6%) were identified. Linoleic acid amount remains unchanged at 25 mM, while it increased with raising NaCl concentrations. However, oleic acid amount decreased only at 25 mM and no effect was observed at 50 and 75 mM. Fatty acid percentages were differently affected by salt. The oleic/linoleic ratio was reduced with raising NaCl concentrations.     

Mapping QTL controlling fatty acid composition in a doubled haploid rapeseed population segregating for oil content

Increasing oil content and improving the fatty acid composition in the seed oil are important breeding goals for rapeseed (Brassica napus L.). The objective of the study was to investigate a possible relationship between fatty acid composition and oil content in an oilseed rape doubled haploid (DH) population. The DH population was derived from a cross between the German cultivar Sollux and the Chinese cultivar Gaoyou, both having a high erucic acid and a very high oil content. In total, 282 DH lines were evaluated in replicated field experiments in four environments, two each in Germany and in China. Fatty acid composition of the seed oil was analyzed by gas liquid chromatography and oil content was determined by NIRS. Quantitative trait loci (QTL) for fatty acid contents were mapped and their additive main effects were determined by a mixed model approach using the program QTLMapper. For all fatty acids large and highly significant genetic variations among the genotypes were observed. High heritabilities were determined for oil content and for all fatty acids (h ² = 0.82 to 0.94), except for stearic acid content (h ²= 0.38). Significant correlations were found between the contents of all individual fatty acids and oil content. Closest genetic correlations were found between oil content and the sum of polyunsaturated fatty acids (18:2 + 18:3; r _G = −0.46), the sum of monounsaturated fatty acids (18:1 + 20:1 + 22:1; r _G = 0.46) and palmitic acid (16:0; r _G = −0.34), respectively. Between one and eight QTL for the contents of the different fatty acids were detected. Together, their additive main effects explained between 28% and 65% of the genetic variance for the individual fatty acids. Ten QTL for fatty acid contents mapped within a distance of 0 to 10 cM to QTL for oil content, which were previously identified in this DH population. QTL mapped within this distance to each other are likely to be identical. The results indicate a close interrelationship between fatty acid composition and oil content, which should be considered when breeding for increased oil content or improved oil composition in rapeseed.     

Effects of constant light on circadian rhythmicity in mice lacking functional <Emphasis Type="Italic">cry</Emphasis> genes: dissimilar from <Emphasis Type="Italic">per</Emphasis> mutants

Mutations in each of the genes mPer1, mPer2, mCry1 and mCry2 separately cause deviations from the wild type circadian system. Differences between these mutant strains have inspired the hypothesis that the duality of circadian genes (two mPer and two mCry genes involved) is related to the existence of two components in the circadian oscillator (Daan et al., J Biol Rhythms 16:105–116, 2001). We tested the predictions from this theory that the circadian period (τ) lengthens under constant illumination (LL) in mCry1 and mPer1 mutant mice, while it shortens in mCry2 and mPer2 mutants. mCry1 ^−/− and mCry2 ^−/− knockout mice both consistently increased τ with increasing light intensity, as did wild type mice. With increasing illumination, rhythmicity is reduced in mCry1, mCry2 and mPer1, but not in mPer2 deficient mice. Results for mPer mutant mice are in agreement with data reported on these strains earlier by Steinlechner et al. (J Biol Rhythms 17:202–209, 2002), and also with the predictions from the model. The increase in cycle length of the circadian system by light in the mCry2 deficient mice violates the predictions. The model is thereby rejected: the mCry genes do not play a differential role, although the opposite responses of mPer mutants to light remain consistent with a functional Evening–Morning differentiation.     

Effect of growth temperature on the fatty acid composition of Mycobacterium phlei

In Mycobacterium phlei, fatty acid unsaturation increased with decreasing temperature. The 10-hexadecenoic acid content increased as the temperature was reduced from 35°C to 26–20°C. At lower temperatures tuberculostearic acid decreased while oleic and linoleic acids increased, the latter being found in M. phlei for the first time. Concomitantly palmitic acid content decreased, and the 6- and 9-hexadecenoic acids increased slightly on reducing the temperature from 35 to 10°C. Thus, down to 26–20°C palmitic acid was mainly replaced by 10-hexadecenoic acid. From this range down to 10°C, palmitic and tuberculostearic acids were replaced by oleic and linoleic acids. Consequently, fatty acid branching decreased and mean chain length increased, as the temperature was reduced. These observations support the view that regulation of membrane fatty acid composition is part of microbial temperature adaptation, and that themechanism behind the responses might be more complex than generally believed.Abbreviations ACP acyl carrier protein - FAS I (Type I) fatty acid synthetase I - FAS II (Type II) fatty acid synthetase II - MGLP methylglucose containing lipopolysaccharide - MMP methylmannose containning polysaccharide     

Polar lipid fatty acids,LPS-hydroxy fatty acids,and respiratory quinones of three <Emphasis Type="Italic">Geobacter</Emphasis> strains,and variation with electron acceptor

The polar lipid fatty acids, lipopolysaccharide hydroxy-fatty acids, and respiratory quinones of Geobacter metallireducens str. GS-15, Geobacter sulfurreducens str. PCA, and Geobacter bemidjiensis str. Bem are reported. Also, the lipids of G. metallireducens were compared when grown with Fe³⁺ or nitrate as electron acceptors and G. sulfurreducens with Fe³⁺ or fumarate. In all experiments, the most abundant polar lipid fatty acids were 14:0, i15:0, 16:1ω7c, 16:1ω5c, and 16:0; lipopolysaccharide hydroxy-fatty acids were dominated by 3oh16:0, 3oh14:0, 9oh16:0, and 10oh16:0; and menaquinone-8 was the most abundant respiratory quinone. Some variation in lipid profiles with strain were observed, but not with electron acceptor. D. C. White: Deceased.     

Isolation of biochemical mutants using haploid mesophyll protosplasts of Hyoscyamus muticus

The question of whether membrane expansion, which is caused by anesthetics in animal systems, alters the lipid composition of plant cell membranes was investigated. We have measured the effects of several anesthetics on the relative amounts of the principal fatty acids from the polar lipids of barley (Hordeum vulgare L.) root membranes. Procaine, dibucaine, tetracaine, chloroform and, to a lesser degree, methanol increased the proportions of palmitic, stearic and oleic acids and decreased the proportions of linoleic and linolenic acids. Ethanol had no significant effect. Total amounts of the fatty acids from the polar lipids of roots in procaine solution decreased markedly so that all of the acids decreased in amount. The anesthetic was effective as soon as the roots were introduced to the solution and the changes progressed at constant rates for 6 h. Only the polar membrane lipids were altered; other lipids were not affected. Increased hydrostatic pressure of about 1.0 MPa largely prevented the anesthetic effects, including the decrease in the total amounts of the fatty acids. Hydrostatic pressure as high as 2 MPa had no effect per se on the membrane lipid composition. These results indicate that anesthetics cause expansion of the root membranes which results in the lipid changes. That a compositional change in the membrane lipids involves a conformational change such as expansion is an indication of the nature of the link between changes in the membrane lipids and changes in function of areas where hydrophilic ions permeate.Abbreviations 16:0 palmitic acid - 18:0 stearic acid - 18:1 oleic acid - 18:2 linoleic acid - 18:3 linolenic acid     

Co-expression of the borage Δ6 desaturase and the Arabidopsis Δ15 desaturase results in high accumulation of stearidonic acid in the seeds of transgenic soybean

Two relatively rare fatty acids, γ-linolenic acid (GLA) and stearidonic acid (STA), have attracted much interest due to their nutraceutical and pharmaceutical potential. STA, in particular, has been considered a valuable alternative source for omega-3 fatty acids due to its enhanced conversion efficiency in animals to eicosapentaenoic acid when compared with the more widely consumed omega-3 fatty acid, α-linolenic acid (ALA), present in most vegetable oils. Exploiting the wealth of information currently available on in planta oil biosynthesis and coupling this information with the tool of genetic engineering it is now feasible to deliberately perturb fatty acid pools to generate unique oils in commodity crops. In an attempt to maximize the STA content of soybean oil, a borage Δ⁶ desaturase and an Arabidopsis Δ¹⁵ desaturase were pyramided by either sexual crossing of transgenic events, re-transformation of a Δ⁶ desaturase event with the Δ¹⁵ desaturase or co-transformation of both desaturases. Expression of both desaturases in this study was under the control of the seed-specific soybean β-conglycinin promoter. Soybean events that carried only the Δ¹⁵ desaturase possessed a significant elevation of ALA content, while events with both desaturases displayed a relative STA abundance greater than 29%, creating a soybean with omega-3 fatty acids representing over 60% of the fatty acid profile. Analyses of the membrane lipids in a subset of the transgenic events suggest that soybean seeds compensate for enhanced production of polyunsaturated fatty acids by increasing the relative content of palmitic acid in phosphatidylcholine and other phospholipids.     

Growth regulators influence the fatty acid profiles of in vitro induced jojoba somatic embryos

Inducing somatic embryogensis from jojoba [Simmondsia chinensis (Link) Schneider] explants to produce artificial seeds in the laboratory (in vitro) may prove highly profitable, as the seeds contain a characteristic liquid wax of economic importance in industry, nutrition and medicine. Thus, there is a need to examine the effect of the factors involved in the in vitro process on the quality and quantity of the synthesized fatty acids in comparison with those naturally produced in vivo. Immature zygotic embryos and mature leaf explants were cultured on Murashige and Skoog basal medium (MS) supplemented with various levels of 2,4-D, BA and sucrose. Embryogenic calluses developed from the zygotic embryos and leaf explants over a period of 2–4 weeks with the highest response at 0.4 μM 2,4-D, 2.2/4.4 μM BA and 117 mM sucrose (4%). Following induction, the zygotic embryo derived somatic embryos developed to the globular, heart, torpedo, and cotyledon stages. Direct somatic embryogenesis was observed with some of the zygotic embryo explants. Leaf-derived embryogenic calluses did not mature on any of the maturation/germination media examined up to 4 weeks of culture. Analysis of fatty acids indicated that the mature seeds are characterized with long chain saturated fatty acids C22:0 behenic Acid. The zygotic embryo-derived somatic embryos (SE-Z) and leaf-derived somatic embryos (SE-L) are characterized with the induction of the essential polyunsaturated fatty acid C18:2 (omega-6) linoleic acid, (omega-3) alpha-linolenic acid (ALA), with higher values of long chain saturated fatty acids C16:0 palmitic acid and monounsaturated fatty acid C18:1 oleic acid. These results indicate that manipulating the growth regulators in the induction media influenced the fatty acids synthesis and hence the fatty acids profile in jojoba somatic embryos.     

Analysis of whole cellular fatty acids and anastomosis relationships of binucleate Rhizoctonia spp. associated with Ceratobasidium cornigerum

Previous research has demonstrated that whole cellular fatty acids analysis is a useful tool for identifying and establishing taxonomic relationships between anastomosis groups (AGs) and related Rhizoctonia isolates. In this experiment, the composition of fatty acid of 28 isolates of teleomorph genus Ceratobasidium cornigerum, consisting of binucleate Rhizoctonia, AG-A, AG-B(o), AG-C, AG-P, and AG-Q, was evaluated using gas chromatography. Eleven fatty acids identified, i.e., myristic, pentadecanoic, palmitic, 2-hydroxypalmitic, palmitoleic, heptadecanoic, 9-heptadecenoic, stearic, oleic, linoleic, and linolenic acids, were present in isolates of AG-A, AG-B(o), AG-C, AG-P, and AG-Q. The major fatty acids, palmitic, oleic, and linoleic acids, were common in all isolates, constituting 87.1% to 94.7% of the whole cellular fatty acids identified. Isolates within the same AG were closely clustered, whereas isolates from different AGs were clearly and distinctly clustered based on average linkage cluster analysis of whole cellular fatty acids. Principal-component analysis generated from all fatty acids also confirmed the divergent separation of the 5 AGs of binucleate Rhizoctonia.     

Bile formation and hepatic plasma membrane composition in guinea-pigs and rats

We compared bile formation, and biliary and liver plasma membrane composition in guinea-pigs and rats in an attempt to explain the observation that the bile flow rate and the bile acid independent fraction of bile flow (BAIF) in guinea-pigs is about five to seven times higher than in rats. Analysis of electrolytes in bile showed that bicarbonate was significantly [acid] higher in guinea-pigs while Cl⁻, phosphate and Ca²⁺ were markedly lower than in rats. High bile independent secretion in guinea-pigs was associated with a significantly lower concentration of total bile acid, phospholipid and cholesterol than in rats. Bile acid distribution studies showed that glycine conjugated chenodeoxycholate and ketolithocholate were the main bile acids in guinea-pigs, while taurine conjugated cholate and muricholate were the predominant bile acids in rats. Total fatty acid analysis of bile indicated that in rats the major fatty acids were palmitic acid (C16:0) and linoleic acid (C18:2, n-6). In guinea-pigs, the contribution of these fatty acids was lower than in rats and compensated with a significantly higher percentage of oleic acid (C18:1, n-9). Concentrations of anionic polypeptide fraction (APF), an acidic calcium binding apoprotein closely associated with biliary phospholipid and cholesterol secretion was also significantly lower in guinea-pigs. Canalicular plasma membrane analysis showed that as compared with rats, specific activities of Na⁺,K⁺ ATPase, and cholesterol and phospholipid content were markedly lower in guinea-pigs. Total fatty acid analysis of the membrane revealed that palmitic acid (C16:0), stearic acid (C18:0) and linoleic acid (C18:2, n-6) were the predominant fatty acids in guinea-pigs, while palmitic acid (C16:0), stearic acid (C18:0) and arachidonic acid (C20:4, n-6) were the most important in rats. Thus, high bile flow rate and BAIF in the guinea-pig may be attributed to the low bile acid concentration (below the critical micellar concentration), secretion of hypercholeretic bile acids (e.g. ketolithocholate) and high bicarbonate output.     

Halimodendrin I, a new acylated triterpene glycoside from Halimodendron halodendron (Fabaceae)

Halimodendrin I, a new acylated triterpene glycoside (1), was isolated and chemically characterized as 3β-O-palmitoyl-28-[3′-palmitoyl-β-d-glucopyranosyl]-olean-12-en-28-oic acid from the aerial part of Halimodendron halodendron (Fabaceae) by IR, 1D and 2D NMR, HR-ESI-MS and LR-ESI-MS experiments. In addition, seven known compounds were isolated and identified as: palmitic acid, glycerol-2-linoleneate, glycerol-1,3-dilinoleneate, ferulic acid, 3-O-methylquercetin, β-sitosterol, and β-sitosterol-3-O-β-d-glucopyranoside. Nine fatty acids were identified and quantified in the saponifiable matter of the hexane extract. These fatty acids are: myristic, n-pentadecanoic, palmitoleic, palmitic, linoleic, oleic, stearic, arachidic, and behenic acids. The volatile oil was isolated by hydrodistillation (0.013%, w/w) with unpleasant smell. Twenty-seven components were identified in the oil by GC/MS.     

Characterization of a novel lipopolysaccharide biosurfactant fromKlebsiella oxitoca

The chemical, physical, and emulsifying properties of BSF-1, which is an extracellular lipopolysaccharide biosurfactant produced byKlebsiella oxytoca strain BSF-1, were studied. BSF-1 was found to be composed mainly of carbohydrate and fatty acids. The average molecular weight was 1,700–2,000 kDa. The polysaccharide fraction containedl-rhamnose,d-galactose,d-glucose, andd-glucuronic acid at a molar ratio of 3∶1∶1∶1. The fatty acid content was 1.1% (w/w) and consisted mainly of palmitic acid (C16∶0), 3-hydroxylauric acid (3-OH-C12∶0), and lauric acid (C12∶0). In terms of thermal properties, BSF-1 was revealed to have inter- and intra-molecular hydrogen bonds. The hydrodynamic volume (intrinsic viscosity) of BSF-1 was 22.8 dL/g. BSF-1 could be maintained as a stable emulsion for 48 h through a low-level reduction in surface tension. The optimal emulsification temperature was 30°C. Emulsification by BSF-1 was efficient at both acidic and neutral pH values.     

Antioxidant activity of <Emphasis Type="Italic">Haematococcus pluvialis</Emphasis> cells grown in continuous culture as a function of their carotenoid and fatty acid content

The influence of culture conditions on the quality of Haematococcus pluvialis biomass is assessed. Continuously grown cells have been characterised with respect to their astaxanthin, fatty acid content, and antioxidant activity and compared with those of non-growing haematocysts. Moderate limitation of nitrate availability (1.7 mM) under continuous growth conditions favoured the production of reddish palmelloid cells whose extracts possessed antioxidant activity equivalent to that of haematocyst extracts, despite the lower astaxanthin content (0.6%d.wt.), which is compensated by a higher fatty acid level (7.6%d.wt.). Green cells produced under nitrate saturation conditions (>4.7 mM) exhibit only 40% antioxidant activity than palmelloid. In addition, the major fatty acid present in palmelloid cells was oleic acid (40%f.a.), whereas, in both green cells and haematocysts, the main fatty acids were myristic, palmitic, and oleic acid (20–30%f.a. each). Biomass extracts were fractionated and analysed. The antioxidant capacity was a function of both the carotenoid and the fatty acid profiles, the antioxidant capacity of astaxanthin diesters fraction being 60% higher than astaxanthin monoesters fraction and twice than free astaxanthin. In such a way, the evaluation of the quality of H. pluvialis biomass must take into account both variables. When considering the production of H. pluvialis biomass for human consumption, special attention should be paid to the one-step continuous system approach for the generation of cells rich in both astaxanthin and fatty acids, as they have high antioxidant activity but without thick hard cell wall.     

The budding bacteria,Pirellula and Planctomyces,with atypical 16S rRNA and absence of peptidoglycan,show eubacterial phospholipids and uniquely high proportions of long chain beta-hydroxy fatty acids in the lipopolysaccharide lipid A

Fatty acids of twelve strains of budding bacteria (Planctomyces and Pirellula spp.), which have atypical 16S rRNA and do not contain peptidoglycan cell walls, were shown to contain typical diacyl polar lipids with no indication of isoprenoid ether lipids suggestive of a relationship with the archaebacteria. The major ester-linked fatty acids of the phospholipids were palmitic, palmitoleic and oleic acids, which are more typical of microeukaryotes than of eubacteria. Lipopolysaccharide lipid A (LPS) was detected; it contained major proportions of long chain normal 3-OH fatty acids (3-OH eicosanoic at 23% and 17% of the total in two strains of Planctomyces, and 3-OH octadecanoic at 18%, and 3-OH palmitic at 11% of the total in one strain of Pirellula). Major portions of long chain 3-OH fatty acids in the LPS are extremely unusual and provide another atypical property of these organisms. Each strain investigated showed a specific total fatty acid composition, reflecting the diversity in 16S rRNA nucleotide catalogues.     

Incorporation of [214C]malonyl CoA into fatty acids by a cell-free extract of Catharanthus roseus suspension culture cells

A cell-free extract containing the enzymes for de-novo synthesis, elongation and desaturation of fatty acids was prepared from cultured cells of Catharanthus roseus G. Don. ¹⁴C-Fatty acids synthesized by the extract from [2-¹⁴C]malonyl CoA substrate were palmitic (16:0), stearic (18:0) and oleic (18:1). Dialyzed extract was active and stable at room temperature and at 4° C, but was inactivated on boiling. There was an absolute requirement for NADPH for incorporation of [2-¹⁴C]malonyl CoA into total fatty acids. Escherichia coli acyl carrier protein stimulated total fatty-acid synthesis without affecting the relative ratio of individual fatty acids. Total fatty-acid synthesis at a rate of 45 nmol·mg^-1 protein·h^-1 occurred at a substrate level of 73 M malonyl CoA, cofactor levels of 500 M NADPH, 30 g·ml^-1 E. coli ACP, and 1.0 mg·ml^-1 extract protein. Total fatty acid synthesis was also sensitive to cerulenin and CoA levels. Variations in the relative abundance of individual ¹⁴C-fatty acids were regulated by concentrations of [¹⁴C]malonyl CoA. NADPH and ferredoxin, as well as by pH, temperature and length of incubation. Fatty-acid synthetase enzymes responsible for [¹⁴C]palmitic acid were rapidly saturated at a low substrate level (0.3 M malonyl CoA). Increasing the level of [2-¹⁴C]malonyl CoA permitted further synthesis of [¹⁴C]stearate and [¹⁴C]oleate. Desaturation of [¹⁴C]stearate to [¹⁴C]oleate was stimulated by increasing the levels of NADPH and ferredoxin. The desaturase and elongase enzymes were sensitive to acidic pH. The desaturase was also unstable at 41° C, although fatty acid synthetase and elongase were unaffected by this temperature.Abbreviation ACP Acyl carrier protein