Cell wall constituents of Microcystis sp. PCC 7806

Cell walls of Microcystis sp. PCC 7806 were purified from cell homogenates by sucrose density centrifugation and Triton X-100 extraction. The outer membrane contained carotenoids, two major peptidoglycan-associated proteins (Mr 49,000 and 52,000), and lipopolysaccharide (LPS) as indicated by the presence of 3-hydroxy fatty acids (3-OH-14:0, 3-OH-16:0, 3-OH-18:0), 4-oxo-18:0 fatty acid, and GlcN as lipid A components in addition to rare O-methyl sugars (2-O-methyl-6-deoxyhexoses I and II). The peptidoglycan (A1 gamma-type) was found to be covalently linked to a wall polysaccharide composed of GlcN, ManN, Man, Glc, and phosphate.     

Cellular fatty acid composition of Haemophilus species, Pasteurella multocida, Actinobacillus Actinomycetemcomitans and Haemophilus vaginalis (Corynebacterium vaginale)

The fatty acid composition of 35 Haemophilus influenzae strains was found to be grossly similar and characterized by relatively large amounts of 14:0, 3-OH-14:0, 16:1 and 16:0. The three C18 fatty acids 18:2, 18:1 and 18:0 were also present, but in much lower concentrations. This general pattern was also found for most of the other species of Haemophilus examined (H. aegyptius, H. aphrophilus, H. canis, H. gallinarum, H. haemolyticus, and H. parainfluenzae). Small but distinct quantitative discrepancies were detected for H. ducreyi and the haemin-independent species H. paraphrohaemolyticus, H. paraphrophilus and H. suis. Actinobacillus actinomycetemcomitans was found to be indistinguishable from H. influenzae. Pasteurella multocida also exhibited a fatty acid pattern closely related to that of Haemophilus, but could be distinguished by its higher concentration levels of the C18 fatty acids. The fatty acid pattern of H. vaginalis was considerably different from those of the other species examined. This species lacked 3-OH-14:0 and 18:2 and contained small amounts of 14:0 and 16:0, whereas 18:1 and 18:0 were the major constituents.     

Fatty acid composition of Mesorhizobium huakuii lipopolysaccharides. Identification of 27-oxooctacosanoic acid

Lipopolysaccharides of three Mesorhizobium huakuii strains carried a number of amide-linked 3-hydroxylated fatty acids including: 3-OH-12:0, 3-OH-i-13:0, 3-OH-20:0, 3-OH-i-21:0, 3-OH-22:0, 3-OH-23:0 and unsaturated 3-OH-22:1. The first three of the above mentioned acids are the main amide-linked fatty acids in the LPS preparations. The main ester-bound fatty acids comprise 16:0, i-17:0, 18:0, 20:0 and 27-OH-28:0. Among minor constituents of lipid A 25-OH-26:0 and 29-OH-30:0 together with some non-polar fatty acids were found. Additionally, the presence of 4-oxo-20:0, 4-oxo-i-21:0 and 4-oxo-22:0 amide-bound fatty acids as well as the 27-oxo-28:0 ester-linked fatty acid were proved. To our knowledge oxo fatty acids are rare constituents of lipopolysaccharides and 27-oxo-28:0 was found for the first time in the LPS preparations from members of Rhizobiaceae.     

Developmental fatty acid changes in different parts of the rat brain

The proportion of 26 fatty acids (FA) in the lipids of the cerebral cortex, subcortical formations (the thalamus, hypothalamus and basal ganglia) and the medulla oblongata was studied in rats aged 5, 10, 14 and 90 days. Very marked developmental changes in the proportion of the various FA were demonstrated in the different parts of the brain. In the cerebral cortex the proportion of 17:1 rose by 285%, 18:3 n-3 by 1820% and 22:6 n-3 by 80%, while the proportion of 14:0, 16:0 and 16:1 fell significantly. In the tissue of subcortical formations we found an increase in the proportion of FA with 18 carbons (18:0 by 40%, 18:1 by 100%, 18:3 n-3 by over 5000%) and a decrease in the proportion of 14:0, 16:0, 16:1 and 20:4 n-6. The situation in medulla oblongata tissue was similar to the one in subcortical formations. On comparing the proportion of FA in individual parts of the CNS in the same age category, we found the smallest number of statistically significant differences in 5-day-old rats. In adult rats we found significant differences chiefly in the proportion of palmitic acid (16:0), oleic acid (18:1), linolenic acid (18:3 n-3) and acids with 20-22 carbons.     

The lipopolysaccharide of the green sulfur bacterium Chlorobium vibrioforme f. thiosulfatophilum

The cell wall lipopolysaccharide of the green sulfur bacterium Chlorobium vibrioforme f. thiosulfatophilum was obtained by the phenol-chloroform-petroleum ether and the hot phenol-water methods, respectively. It contained mannose, glucose, galacturonic acid, glucosamine, glycine, and small amounts of rhamnose, galactose and glucuronic acid. In addition to d-glycero-d-mannoheptose, the corespecific constituents 2-keto-3-deoxyoctonate and l-glycero-d-mannoheptose were found. Polyacrylamide gel-electrophoresis in the presence of sodium deoxycholate gave no indication for the presence of O-specific repeating units. Degradation of the lipopolysaccharide required 10% acetic acid (100° C, 2 h). The lipid A moiety contained the total of glucosamine of the lipopolysaccharide as well as small amounts of 2,3-diamino-2,3-dideoxy-glucose. It was phosphate-free. The fatty acid spectrum comprised 3-OH-14:0, 3-OH-16:0, and iso-3-OH-18:0 besides little 12:0, 14:0 and 16:0. Hydroxylaminolysis and sodium methylate treatment revealed all of the three hydroxy fatty acids to be amidebound.Abbreviations DOC sodium deoxycholate - PAGE polyacrylamide gel-electrophoresis     

Cellular fatty acids as chemical markers for differentiation of Yersinia pestis and Yersinia pseudotuberculosis

Aims:  Gas chromatography (GC) was utilized to investigate the cellular fatty acids (CFAs) composition of 141 Yersinia pestis isolates from different plague foci of China, and 20 Yersinia pseudotuberculosis strains as well.
Methods and Results:  The whole cell fatty acid methyl esters (FAMEs) were obtained by saponification, methylation and extraction followed with analysis using a standardized Microbial Identification System (MIS). Y. pestis and Y. pseudotuberculosis strains are quite similar in major CFA profiles, which include 16:0, 17:0 cyclo, 3-OH-14:0, 16:1ω7c and 18:1ω7c, accounting for more than 80% of the total CFAs.
Conclusions:  Yersinia pestis could be easily differentiated from Y. pseudotuberculosis by plotting the ratios of some CFA pairs, i.e.,14:0/18:0 vs 18:1ω7c/18:0, 3-OH-14:0/18:0 vs 18:1ω7c/18:0, 16:1ω7c/18:0 vs 18:1ω7c/18:0, 12:0/18:0 vs 18:1ω7c/18:0 and 12:0 ALDE/18:0 vs 16:1ω7c/18:0 fatty acids.
Significance and Impact of the Study:  In the present study, the normalized Sherlock MIS and Sherlock standard libraries were used to analyse the fatty acid composition of different strains of Y. pestis and Y. pseudotuberculosis . Meanwhile, ratios of certain CFA components were found to serve as chemical markers for differentiating the two closely related bacteria that are difficult to be differentiated by simply comparing CFA profiles based on other researches.     

Lipopolysaccharides from six strains of Acetobacter diazotrophicus

Abstract Lipopolysaccharides from six nitrogen-fixing strains of Acetobacter diazotrophicus (PR2, PAL3, PAL5, PR4, PR14, PR20), isolated from sugarcane, were purified by phenol-water extraction and ultracentrifugation. The relatively large molecular mass observed by SDS-PAGE indicated that the lipopolysaccharides of each strain possessed an O-side chain. Analysis of each lipopolysaccharide by colorimetric assays and by gas liquid chromatography/mass spectrometry combination showed that the core and lipid A composition was similar for all strains, containing 3-deoxy-d-manno-2-octulosonic acid, glucosamine and fatty acid (16-0, 3-OH-14, 2-OH-16:0, 3-OH-16:0). The neutral sugar composition showed the predominance of 6-deoxy-hexose (rhamnose and fucose) and ribose, in comparison with hexose (glucose, galactose, mannose). The presence of 6-deoxy-hexose and ribose containing O-side chains is discussed as a way of discriminating A. diazotrophicus from other Acetobacter species.     

Chemical studies on the lipopolysaccharide of Rhizobium meliloti 10406 and its lipid A region

The structure of the lipopolysaccharide from Rhizobium meliloti 10406, a derivative of the wild-type strain MVII-1, was examined. The compositional analysis of its polysaccharide moiety demonstrated lack of heptose(s), but high contents in glucose, galacturonic acid and 2-keto-3-deoxy-octonate (dOclA) as characteristic features. The lipid A moiety consisted of a -1,6 linked glucosamine disaccharide carrying ester (at C-4) and glycosidically (at C-1) linked phosphate residues, both present exclusively as monoester phosphates but not as phosphodiesters. Ester- and amidelinked 3-hydroxy fatty acids were mostly present as non-3-O-acylated residues. Laser desorption mass spectrometry (LD-MS) revealed heterogeneity in the fatty acid substitution, as was also indicated by the non-stoichiometric ratios obtained by quantitative fatty acid analysis. The predominating lipid A structure contained at the reducing glucosamine residue ester-linked 3-hydroxy-tetradecanoic acid (3-OH-14:0) and amide-linked 3-OH-18:0, or 3-OH-18:1, respectively. The distal (non-reducing) glucosamine carried ester-bound the recently discovered 27-hydroxyoctacosanoic acid and 3-OH-14:0 and, as amide-linked fatty acid, mostly 3-hydroxy-stearic acid (3-OH-18:0).The isolated lipopolysaccharide exhibited a high extent of lethal toxicity in galactosamine-treated mice, comparable to that of enterobacterial lipopolysaccharide. The structural relationship of LPS and lipid A of Rhizobium meliloti to other rhizobial lipopolysaccharides and lipid A's with respect to questions of taxonomy and of phylogenetic relationships will be discussed.Abbreviations LPS lipopolysaccharide - dOclA 3-deoxy-D-mannooctulosonic acid (KDO) - GalA galacturonic acid - DOC sodium deoxycholate - PAGE polyacrylamide gel electrophoresis - LD-MS laser desorption-mass spectrometry     

Incorporation of newly synthesized fatty acids into cytosolic glycerolipids in pea leaves occurs via acyl editing

In expanding pea leaves, over 95% of fatty acids (FA) synthesized in the plastid are exported for assembly of eukaryotic glycerolipids. It is often assumed that the major products of plastid FA synthesis (18:1 and 16:0) are first incorporated into 16:0/18:1 and 18:1/18:1 molecular species of phosphatidic acid (PA), which are then converted to phosphatidylcholine (PC), the major eukaryotic phospholipid and site of acyl desaturation. However, by labeling lipids of pea leaves with [(14)C]acetate, [(14)C]glycerol, and [(14)C]carbon dioxide, we demonstrate that acyl editing is an integral component of eukaryotic glycerolipid synthesis. First, no precursor-product relationship between PA and PC [(14)C]acyl chains was observed at very early time points. Second, analysis of PC molecular species at these early time points showed that >90% of newly synthesized [(14)C]18:1 and [(14)C]16:0 acyl groups were incorporated into PC alongside a previously synthesized unlabeled acyl group (18:2, 18:3, or 16:0). And third, [(14)C]glycerol labeling produced PC molecular species highly enriched with 18:2, 18:3, and 16:0 FA, and not 18:1, the major product of plastid fatty acid synthesis. In conclusion, we propose that most newly synthesized acyl groups are not immediately utilized for PA synthesis, but instead are incorporated directly into PC through an acyl editing mechanism that operates at both sn-1 and sn-2 positions. Additionally, the acyl groups removed by acyl editing are largely used for the net synthesis of PC through glycerol 3-phosphate acylation.     

立克次体脂肪酸图谱及其相似性判别

用气相色谱-质谱法分析了7株立克次体浓盐乙醚纯化物的脂肪酸成分,即R．ProwazekiE株、R. conorii Simkoo株、R.rickettsii R株、R sibirica Barbash株和246株、R．Si—nkiangensis Jinghe。株以及R.heilugkiangensis 54株。所得脂肪酸色谱图中有近50个色谱峰,初步确认有以下1 6种： C11:10、2OH—C10:1、C12:0、2OH—C12:0、C13:0、C14:0、C15:0、3OH-C14:0,C16:1、C16:0、C17:0、C18:1、C18:1、C18:0、C19:0和C22:0。其中主要成分是直链饱和脂肪酸C16:0、C18:0及C14:0与不饱和脂肪酸C18:1、C18:2及C16:1。实验菌株脂肪酸图谱经改进的Kulik—Vincent相似系数法处理后,精河株和246株的相似系数为9 7.09%,54株和其他菌株的相似系数在81．6--94．6％之间。     

Sheath and outer membrane components from the cyanobacterium Fischerella sp. PCC 7414

A purified sheath fraction and an outer membrane fraction were obtained from the cyanobacterium Fischerella sp. PCC 7414. The sheath had a fine structure with osmiophilic fibers running in parallel to the cell surface in two distinct layers. The sheath fraction contained mainly neutral sugars (Glc, Man, Gal, Xyl, Fuc, 2-O-methylhexose), GlcN, uronic acids, and minor components such as amino acids, sulfate, phosphate, and fatty acids. The protein moiety was removable from the sheath fraction by treatment with boiling sodium dodecyl sulfate. The presence of three different 3-hydroxy fatty acids (3-OH-14:0, 3-OH-16:0, 3-OH-18:0) in addition to GlcN indicated the presence of lipopolysaccharide in the outer membrane. One major (M_r 50,000) and two minor (M_r 54,000 and 65,000) proteins were detected as constituents of the outer membrane.Abbreviations A₂pm diaminopimelic acid - GLC gas-liquid chromatography - GlcN glucosamine - Ino inositol - MurN muramic acid - PAGE polyacrylamide gel electrophoresis - SDS sodium dodecyl sulfate     

Lipopolysaccharide in the outer membrane of the filamentous prochlorophyte Prochlorothrix hollandica

Abstract A lipopolysaccharide (LPS) fraction was isolated from Prochlorothrix hollandica by hot phenol/water extraction. Negatively stained preparations of an aqueous LPS dispersion showed the triple-layered appearance of the LPS aggregates. Glucose (main sugar), rhamnose, fucose, galactose, mannose, xylose, and 3- O -methyl-xylose were found as the constituents of the polysaccharide moiety. Glucosamine and the 3-hydroxy fatty acids, 3-OH-16:0, 3-OH-14:0, and the rarely detected iso-3-OH-15:0, constitute the lipid A of the LPS. l -glycero- d -manno-heptose and 3-deoxy- d -manno-2-octulosonic acid (dOclA), typical components of inner core oligosaccharides from enterobacterial LPS, were lacking in the isolated LPS fraction from Prochlorothrix hollandica .     

Cell wall and sheath constituents of the cyanobacterium Gloeobacter violaceus

Sheaths isolated from Gloeobacter violaceus were found to be composed of a major polysaccharide moiety (glucose, galactose, rhamnose, mannose, arabinose), a protein moiety, and negatively charged components (glucuronic acids, phosphate, sulfate). Outer membrane polypeptide patterns were dominated by two major peptidoglycan-associated proteins (M_r 62,000 and 53,000). Lipopolysaccharide constituents were glucosamine, 3-hydroxy fatty acids (3-OH-14:0, anteiso-3-OH-15:0, 3-OH-16:0, 3-OH-18:0), carbohydrates, and phosphate. A1-type peptidoglycan and non-peptidoglycan components (mannosamine, glucose, mannose, and glucosamine) indicated the presence of a peptidoglycan-polysaccharide complex in the cell walls of Gloeobacter violaceus.Abbreviations A₂pm diaminopimelic acid - ATCC American Type Culture Collection - CE cell envelope - CM cytoplasmic membrane - CW cell wall - dOcla 3-deoxy-d-manno-2-octulosonic acid - GalN galactosamine - GlcN glucosamine - GlcUA glucuronic acid - HF hydrofluoric acid - LPS lipopolysaccharide - ManN mannosamine - M relative molecular mass - MurN muramic acid - MurN-6-P muramic acid-6-phosphate - OMe O-methyl - PAGE polyacrylamide gel electrophoresis - PCC Pasteur Culture Collection - SDS sodium dodecyl sulfate - SH sheath     

The lipopolysaccharides of Rhodospirillum rubrum,Rhodospirillum molischianum,and Rhodopila globiformis

The cell wall lipopolysaccharides from three phototrophic species of the alpha₁-group of Proteobacteria, Rhodospirillum rubrum, Rhodospirillum molischianum, and Rhodopila globiformis were isolated and chemically characterized. Sodium deoxycholate polyacrylamide gel electrophoresis patterns revealed that the lipopolysaccharides of all three species possess O-chains. They are composed of repeating units only in R. molischianum and R. globiformis. The presence of l-glycero-d-mannoheptose and 2-keto-3-deoxyoctonate indicated core structures in all three lipopolysaccharides. Glucosamine was found as backbone amino sugar in lipid A of R. molischianum and R. rubrum, while R. globiformis has 2,3-diaminoglucose as backbone amino sugar. The latter species also differed from the two former ones in its content of hydroxy fatty acids (3-OH-14:0, 3-OH-16:0 in R. rubrum and R. molischianum and 3-OH-14:0, 3-OH-18:0 and 3-OH-19:0 (possibly iso- or anteisobranched) in R. globiformis).Abbreviations DOC-PAGE sodium deoxycholate polyacrylamide gel electrophoresis - GC/MS combined gas-liquid chromatography/mass spectrometry - KDO 2-keto-3-deoxyoctonate     

Effects of supplementation of maize silage diets with extruded linseed, vitamin E and plant extracts rich in polyphenols, and morning v. evening milking on milk fatty acid profiles in Holstein and Montbéliarde cows

The aim of this study was to evaluate the effects on dairy performance and milk fatty acid (FA) composition of (i) supplementation with extruded linseed (EL), (ii) supplementation with synthetic or natural antioxidants, namely vitamin E and plant extracts rich in polyphenols (PERP), (iii) cow breed (Holstein v. Montbéliarde) and (iv) time of milking (morning v. evening). After a 3-week pre-experimental period 24 lactating cows (12 Holstein and 12 Montbéliarde) were divided up into four groups of six cows: the first group received a daily control diet (diet C) based on maize silage. The second group received the same diet supplemented with EL (diet EL, fat level approximately 5% of dietary dry matter (DM)). The third group received the EL diet plus 375 IU/kg diet DM of vitamin E (diet ELE). The fourth group received the ELE diet plus 10 g/kg diet DM of a PERP mixture (diet ELEP). Compared with the diet C, feeding EL-rich diets led to lower concentrations of total saturated FA (SFA) and higher concentrations of stearic and oleic acids, each trans and cis isomer of 18:1 (except c12-18:1), non-conjugated isomers of 18:2, some isomers (c9t11-, c9c11- and t11t13-) of conjugated linoleic acid (CLA), and 18:3n-3. The vitamin E supplementation had no effect on milk yield, milk fat or protein percentage and only moderate effects on milk concentrations of FA (increase in 16:0, decreases in 18:0 and t6/7/8-18:1). The addition of PERP to vitamin E did not modify milk yield or composition and slightly altered milk FA composition (decrease in total saturated FA (SFA) and increase in monounsaturated FA (MUFA)). The minor effects of vitamin E may be partly linked to the fact that no milk fat depression occurred with the EL diet. During both periods the Holstein cows had higher milk production, milk fat and protein yields, and milk percentages of 4:0 and 18:3n-3, and lower percentages of odd-branched chain FA (OBCFA) than the Montbéliarde cows. During the experimental period the Holstein cows had lower percentages of total cis 18:1, and c9,c11-CLA, and higher percentages of 6:0, 8:0, t12-, t16/c14- and t13/14-18:1, and 18:2n-6 than Montbéliarde cows because of several significant interactions between breed and diet. Also, the total SFA percentage was higher for morning than for evening milkings, whereas those of MUFA, total cis 18:1, OBCFA and 18:2n-6 were lower. Extruded linseed supplementation had higher effect on milk FA composition than antioxidants, breed or time of milking.     

9 cis,11 trans conjugated linoleic acid (CLA) is synthesised and desaturated into conjugated 18:3 in bovine adipose tissues

Although endogenous synthesis of conjugated linoleic acid (CLA) in the mammary gland of lactating cows has been already well documented, no study has determined so far as to which tissue and/or organ is involved in CLA synthesis in the growing ruminant except one study showing that CLA synthesis does not occur in ruminant liver. In this context, adipose tissue appears to be a good candidate for endogenous synthesis of CLA in the growing ruminant. The aim of this study was to compare the respective metabolisms of 11trans 18:1 (vaccenic acid, VA) and 9cis,11trans 18:2 (rumenic acid) to that of stearic acid (the preferential substrate of Δ9 desaturase) in adipose tissues (subcutaneous, SC and intermuscular, IM) of six Charolais steers by using the in vitromethod of incubated tissue slices. Samples of SC and IM adipose tissues were incubated at 37°C for 16 h under an atmosphere of 95% O2/5% CO2 in a medium supplemented with 0.75 mM of fatty acid (FA) mixture (representative of circulating non-esterified FA) and 186 μM [1-14C]-18:0 or 58.6 μM [1-14C]-VA or 56 μM [1-14C]-9cis,11trans CLA. Viability of explants was verified by measuring metabolic functions (glucose uptake and glucose-6-phosphate dehydrogenase activity). After 16 h of incubation, FA uptake was similar for all FA (18:0, VA and 9cis,11trans 18:2) in both SC and IM adipose tissues (around 40%). Once in adipose tissue, all FA were preferentially esterified (>80% of cell FA) favouring neutral lipid synthesis (around 90% of esterified FA). Stearic acid was highly (27%) desaturated into oleic acid in SC adipose tissue whereas this desaturation was much lower (6.8%) in IM adipose tissue (P < 0.0001). VA was desaturated into 9cis,11trans CLA at a low extent of about 2.5% to 4.4% in both adipose tissues probably because of a limited affinity of Δ9 desaturase for VA. 9cis,11trans CLA was itself converted by desaturation into 6cis, 9cis,11trans 18:3 at the intensity of 10.8% and 14.5% of cell 9cis,11trans CLA in SC and IM adipose tissues, respectively. In conclusion, bovine adipose tissues of the growing ruminant were especially involved in the endogenous synthesis of CLA from VA and in its desaturation into conjugated derivative, mainly 6cis, 9cis,11trans 18:3, of which biological properties need to be elucidated.     

Effect of pH on complex formation between debranched waxy rice starch and fatty acids

Complex formations between debranched waxy rice starch (DBS) and fatty acids (FA) of different hydrocarbon chain lengths (8:0, 10:0, 12:0, 14:0, 16:0, and 18:0) were studied in an aqueous solution by measuring the blue colour stained with iodine. The objective of this study was to understand the effects of the solubility and hydrophobicity of guest molecules (FA) on the complex formation with DBS. Lauric acid (12:0) displayed the greatest complex forming ability with DBS by showing the least blue colour developed with iodine. The effect of pH (3-7) on the DBS/FA complex formation was evaluated by measuring the iodine-scanning spectra of the mixture. Short-chain FA (8:0) displayed less complex formation at pH>or=5, above the pK(a) of fatty acid (approximately 4.8), which suggested that the charge formation of the short-chain FA caused a lower partitioning of the FA into the hydrophobic cavity of the DBS single helix. On the contrary, FA of 10:0-18:0 displayed an increased complex formation at pH>5, which could be attributed to increased solubility of these longer-chain FA at a dissociated and ionized form. The hydrocarbon chain length of the FA had an important impact on the extent of the complex formation. A FA that had a shorter hydrocarbon chain was more soluble in an aqueous solution and more readily formed a complex with DBS. At pH 6 and 7 (above the pK(a)), 10:0 formed less inclusion complexes with DBS than did 12:0. Iodine-scanning spectra showed that the absorbances of all iodine-stained DBS/FA solutions at higher wavelength were substantially lower than that of the iodine-stained DBS alone, suggesting that FA preferentially formed inclusion complexes with DBS of longer chains.     

Influence of an increase in diet structure on milk conjugated linoleic acid content of cows fed extruded linseed

This experiment studied the effect of a modest difference in diet structure value (SV) on milk conjugated linoleic acid (CLA) contents of cows fed diets supplemented with extruded linseed, in situations where the diets provided enough SV and therefore did not induce milk fat depression. Six lactating Holstein cows were used in a crossover design with two treatments ('SV 1.50' and 'SV 1.73') and two periods of 21 days. The 'SV 1.50' diet contained 59% maize silage, 13% soya bean meal, 13% sugar beet pulp and 14% Nutex Compact (containing 56% extruded linseed) (dry matter (DM) basis) and was offered as a restricted total mixed ration. For the 'SV 1.73' diet, 8% wheat straw (DM basis) was added to the 'SV 1.50' diet as an additional structure source. The two diets had a forage-to-concentrate ratio of 59 : 41 and 62 : 38. The inclusion of straw in the diet resulted in an additional intake of NDF (+1110 g/day), which accounted for 90% of the additional intake of OM, whereas additional intakes of the other nutrients were minor. Milk yield and composition did not differ among treatments. The inclusion of straw in the diet did not affect the milk levels of t10-18:1, 18:2n-6, c9-16:1, c9-18:1, c11-18:1, 6:0, 8:0, 20:4 and 20:5. It decreased the milk levels of c9,t11-CLA (2.13% v. 3.03% of fatty acids (FA) reported, P < 0.001), t11-18:1 (4.99% v. 7.10% of FA reported, P < 0.001), 18:3n-3, t9-16:1 and t9-18:1, while it increased the milk levels of 6:0-14:0 (20.90% v. 19.69% of FA reported, P < 0.01), 16:0 (26.55% v. 25.25% of FA reported, P < 0.01), 18:0 (13.54% v. 12.59% of FA reported, P < 0.001), 17:0, 20:0 and 22:5. Regarding the ratio between FA, the inclusion of straw increased the 18:0/total C18 FA ratio (37.74% v. 32.07%, P < 0.001), whereas it decreased the total trans-C18 FA/total C18 FA ratio (15.46% v. 20.34%, P < 0.001), the t11-18:1/total C18 FA ratio (13.70% v. 17.95%, P < 0.01) and the c9,t11-CLA/total C18 FA ratio (5.82% v. 7.64%, P < 0.001). We conclude from this experiment that even a modest increase in SV to a diet supplemented with extruded linseed, yet already providing enough SV, alters the rumen lipid metabolism and, hence, CLA levels in milk fat.     

Characterization of Aspergillus species based on fatty acid profiles

Cellular fatty acid (FA) composition was utilized as a taxonomic tool to discriminate between different Aspergillus species. Several of the tested species had the same FA composition and different relative FA concentrations. The most important FAs were palmitic acid (C16:0), estearic acid (C18:0), oleic acid (C18:1) and linoleic acid (C18:2), which represented 95% of Aspergillus FAs. Multivariate data analysis demonstrated that FA analysis is a useful tool for differentiating species belonging to genus Aspergillus. All the species analyzed showed significantly FA acid profiles (p < 0.001). Furthermore, it will be possible to distinguish among Aspergillus spp. in the Flavi Section. FA composition can serve as a useful tool for the identification of filamentous fungi.     

Inter-and intraspecific differences in fatty acid composition of freshwater crustacean zooplankton

1. The composition of fatty acids (FA) from C14 to C18 was measured for edible seston and for individual Daphnia galeata , Diaphanosoma brachyurum and Eodiaptomus japonicus from Lake Biwa using a pyrolysis–gas chromatography (Py–GC) method. Based on the relative abundance of the FA, inter-and intraspecific differences in composition were examined.
2. Among the FA, C16 : 0 was the most abundant, both in the three zooplankton species and in edible seston smaller than 20 μm, suggesting that the composition of the zooplankton was roughly reflected by their diet. However, the abundance of C18 : 1 relative to C16 : 1 and C18 : 0 was much higher in each zooplankton species than in the diet.
3. Comparison of the relative abundance of FA among the three zooplankton species revealed that intraspecific differences in FA composition are greater than interspecific differences. These results indicate that variability in FA composition is not necessarily species-specific, and can be obscured by variation in composition between individuals.