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.     

Proximate composition, fatty acid and lipid class composition of the muscle from deep-sea teleosts and elasmobranchs

Proximate composition of muscle was determined for the following deep-sea fish species: roughhead grenadier (Macrourus berglax), mora/deep-sea cod (Mora moro), Portuguese dogfish (Centroscymnus coelolepis), black dogfish (Centroscyllium fabricii), leafscale gulper shark (Centrophorus squamosus), greater lantern shark (Etmopterus princeps), smalleyed rabbitfish/ghostshark (Hydrolagus affinis), birdbeak dogfish (Deania calcea) and two species of smooth head (Alepocephalus bairdii and Alepocephalus agassizii). The first eight species contained less than 1% fat in the muscle, while the last two contained 3.0% and 3.6% fat, respectively. Fatty acid and lipid class composition was determined for the first five fish species and showed that the dominant class of lipids was phospholipids. The lipids consisted mainly of polyunsaturated fatty acids (PUFA), and docosahexaenoic acid (DHA) was the dominant fatty acid. Roughhead grenadier and mora showed resemblance to cod (Gadus morhua) regarding protein content, fat content and fatty acid composition. However, the muscle from the deep-sea fish species did contain a higher proportion of arachidonic acid (20:4n-6) than cod muscle.     

The distribution of fatty acids including petroselinic and tariric acids in the fruit and seed oils of the Pittosporaceae, Araliaceae, Umbelliferae, Simarubaceae and Rutaceae

The fatty acid composition of the fruit oils or seed oils of Pittosporaceae (eight genera, 10 species), Araliaceae (two species), Simarubaceae (three species), and of one umbelliferous and one rutaceous species were determined by gas chromatography, argentation TLC and ozonolysis. In the Pittosporaceae, in which the major C₁₈ fatty acid of all species was either oleic acid (18:1, 9c) or linoleic acid (18:2, 9c, 12c), large amounts of C₂₀ and C₂₂ fatty acids seem to occur regularly. Petroselinic (18:1, 6c) and tariric (18:1, 6a) acids were absent. However, petroselinic acid was the major fatty acid in the Araliaceae and Umbelliferae. In these two families only small amounts of C₂₀ and C₂₂ acids were detected and tariric acid was absent. The Rutales contained relatively high amounts of trans-octadecenoic acids (18:1, 9t). Tariric acid was the major fatty acid in the two species of Picramnia (Simarubraceae), which also contained small amounts of petroselinic acid. The major fatty acids in Ailanthus glandulosa (Simarubaceae) and Phellodendron amurense (Rutaceae) were linoleic or linolenic acid (18:3, 9c, 12c, 15c); these species contained neither tariric nor petroselinic acid and the levels of C₂₀ and C₂₂ fatty acids were low. The appearance of schizogenous resin canals and polyacetylenes and the absence of iridoids and petroselinic acid allows the Pittosporaceae to be separated from the Rutales and Araliales and to be placed in an independent order, the Pittosporales. Arguments for a rather close relationship of the Pittosporales to the Araliales and Cornales (including the Escalloniaceae) are presented.     

Fatty Acids in the Genus Bacillus I. Iso- and Anteiso-Fatty Acids as Characteristic Constituents of Lipids in 10 Species

Fatty acids produced by 22 strains of 10 species of the genus Bacillus were analyzed on a very efficient and selective gas-liquid chromatographic column. All of the 10 species, alvei, brevis, cereus, circulans, licheniformis, macerans, megaterium, polymyxa, pumilus, and subtilis, produced eight fatty acids, six branched (anteiso-C(15), anteiso-C(17), iso-C(14), iso-C(15), iso-C(16), and iso-C(17)) and two normal (n-C(14) and n-C(16)). In all cases, the six branched-chain fatty acids made up over 60% of the total fatty acids. In addition to the eight fatty acids, B. cereus produced four extra fatty acids, three branched (anteiso-C(13), iso-C(12), and iso-C(13)) and one monoenoic-n-C(16). Furthermore, there were distinct differences in the relative amounts of fatty acids produced between B. cereus and the remaining nine species. B. cereus produced iso-C(15) fatty acid in the largest amount on a glucose-yeast extract medium as well as on Pennassay Broth. On the other hand, for the remaining nine species, anteiso-C(15) fatty acid was the major fatty acid from the glucose-yeast extract medium, whereas the amount of iso-C(15) fatty acid from Penassay Broth became comparable to that of anteiso-C(15) fatty acid. Mechanisms and various factors affecting the fatty acid distribution pattern in the 10 Bacillus species are discussed.     

Specificity of fatty acid composition of highly migratory fish. A comparison of docosahexaenoic acid content in total lipids extracted in various organs of bonito (Euthynnus pelamis)

Fatty acid composition of lipids in various organs of the bonito (Euthynnus pelamis), a typical species within the tuna species, caught in the sea off the Pacific coast of Japan, was determined by gas-liquid chromatography. The major fatty acids of all organs examined were palmitic acid (16:0), palmitoleic acid (16:1), oleic acid (18:1), icosapentaenoic acid (20:5), and docosahexaenoic acid (22:6). 22:6 (DHA) was the dominant fatty acid accounting for 25% or more of the total fatty acids in all organs of the bonito, caught in the sea off the Japanese coast.     

Amino acids in seeds and seedlings of the genus Lens

The amino acid content of seeds and 4-day-old seedlings were studied in five species of lentil: Lens culinaris, L. orientalis, L. ervoides, L. nigricans and L. odemensis. Free amino acid and also total protein amino acid content after HCl hydrolysis were determined by HPLC. The nonprotein UV-absorbing amino acids were determined by capillary zone electrophoresis (CZE). The content of free protein amino acids in seeds varied among species and increased dramatically after germination. Asparagine is quantitatively most important in both seed and seedling. The content of free nonprotein amino acids is variable in seeds and seedlings. gamma-Hydroxyarginine, gamma-hydroxyornithine, alpha-aminobutyric acid and taurine were found in both seeds and seedlings. Homoarginine was found in four species but not in L. orientalis while gamma-aminobutyric acid (GABA), alpha-aminoadipic acid (alpha-aaa) and three isoxazolinone derivatives: beta-(isoxazolin-5-on-2-yl)-alanine (BIA), gamma-glutamyl-BIA (gamma-glu-BIA) and 2-carboxymethyl-isoxazolin-5-one (CMI) were found exclusively in the seedlings. CMI was identified for the first time in lentil species. Lathyrine, beta-(2-amino-pyrimidine-4-yl)-alanine, which was reported to be in the seeds of some Lathyrus species was confirmed to be present also in the seedling of L. culinaris (trace amount), L. nigricans and L. odemensis. Trigonelline (N-methyl-nicotinic acid), a plant hormone, is present both in seeds and seedlings in different concentrations except in L. ervoides. The different combination of nonprotein amino acids among the species gives indication of their genetic relationship and might partly explain the varying compatibility for interspecies crossing.     

Differential effects of n-3 fatty acid deficiency on phospholipid molecular species composition in the rat hippocampus

In this study, we have examined the effects of n-3 fatty acid deficient diets on the phospholipids (PL) molecular species composition in the hippocampus. Female rats were raised for two generations on diets containing linoleic acid (18:2n-6), with or without supplementation of alpha-linolenic acid (18:3n-3) or 18:3n-3 plus docosahexaenoic acid (22:6n-3). At 84 days of age, the hippocampal phospholipids were analyzed by reversed phase HPLC-electrospray ionization mass spectrometry. Depleting n-3 fatty acids from the diet led to a reduction of 22:6n-3 molecular species in phosphatidylcholine (PC), phosphatidylethanolamine (PE), PE-plasmalogens (PLE), and phosphatidylserine (PS) by 70-80%. In general, 22:6n-3 was replaced with 22:5n-6 but the replacement at the molecular species level did not always occur in a reciprocal manner, especially in PC and PLE. In PC, the 16:0,22:6n-3 species was replaced by 16:0,22:5n-6 and 18:0,22:5n-6. In PLE, substantial increases of both 22:5n-6 and 22:4n-6 species compensated for the decreases in 22:6n-3 species in n-3 fatty acid deficient groups. While the total PL content was not affected by n-3 deficiency, the relative distribution of PS decreased by 28% with a concomitant increase in PC.The observed decrease of 22:6n-3 species along with PS reduction may represent key biochemical changes underlying losses in brain-hippocampal function associated with n-3 deficiency.     

The distribution of pyrophosphatidic acid in nature.

The occurrence of a novel phospholipid, pyrophosphatidic acid, in the lipid extracts of yeasts (23 species), bacteria (E. coli), algae (chlorella), mammalia (human, rabbit, guinea pig, and mouse), insect (cockroach), fish (carp), mollusc (clam), and spermatophyta (spinach) was investigated. Pyrophosphatidic acid was found exclusively in the lipid extracts of several kinds of yeast species, but not in other normal living species (animals, plants, and microorganisms) so far investigated. All of the yeast species containing this lipid belong to the asporogenous yeasts (Cryptococcus neoformans CBS-132, Cryptococcus laurentii Z 6-5, Rhodotorula glutinis H 3-9-1, Rhodotorula rubra AY-2, Kloeckera apiculata KK-3, and Trichosporon cutaneum KC 4-3), and ballistosporogenous yeast (Sporobolomyces salmonicolor WF 174). In contrast, no detectable amount of pyrophosphatidic acid was found in the cellular lipids of ascosporogenous yeasts.     

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.     

New defensive chemical data for ground beetles (Goleoptera: Carabidae): interpretations in a phylogenetic framework

First reports of major defensive chemicals for ground beetles representing four tribes include: Morionini (formic acid), Dercylini (methacrylic and tiglic acids), Catapieseini (formic acid and decyl acetate) and Perigonini (formic acid and dccyl acetate). Multiple species from Loxandrini were sampled and, shown to contain formic acid, not salicylaldehyde as previously reported. Several hexenoic acid compounds were found in the clivinine genus Schizogenius representing a third class of chemicals for that tribe. Salicylaldehyde was found for the first time in a species of Oodini. Additional species from Pterostichini, Patrobini and Odacanthini were sampled and the results were found to be consistent with previously published reports. The taxonomic distribution of defensive secretions is reviewed for tribes across the family Carabidae. The simultaneous occurrence of hydrocarbons and formic acid is noted in phylogenetically more derived carabids. By mapping chemical classes onto a phylogenetic hypothesis, it is shown that formic acid or other relatively strong irritants are correlated with tribes having a high species diversity in tropical regions, whereas tribes exhibiting higher diversity in temperate regions use milder saturated/unsaturatcd earboxylic acids. Based on this phylogenetic interpretation, the evolution and maintenance of formic acid is interpreted as the result of predation pressures and possibly the evolution of chemical mimicry.     

Fatty acid contents and profiles of 16 macroalgae collected from the Irish Coast at two seasons

Due to the established health benefits of omega-3 long-chain polyunsaturated fatty acids (LC-PUFA), there is a globally increasing demand for alternative natural resources with appropriate fatty acid profiles. To assess the suitability of macroalgae as a source, 16 species (nine Phaeophyceae, five Rhodophyta and two Chlorophyta) were collected at two seasons (June and November) from the Irish west Coast, and total fatty acid contents and specific profiles were determined. Total fatty acid contents, expressed per percentage of dry weight, ranged from 6.4 %?±?0.3 (Pelvetia canaliculata, Phaeophyceae) to 0.8 %?±?0.2 (Porphyra dioica, Rhodophyta). Most common fatty acids were palmitic (16:0), oleic (OLE, 18:1 n-9), α-linolenic (ALA, 18:3 n-3), arachidonic (ARA, 20:4 n-6) and eicosapentaenoic (EPA, 20:5 n-3) acids. Fatty acid profiles were highly variable between and within algal groups; red and brown seaweeds were generally richer in LC-PUFA (e.g. 20:4 n-6 and 20:5 n-3), while high levels of saturated fatty acids such as palmitic acid (16:0) were observed in green species. Most omega-3 PUFA-rich species investigated had a omega-6/omega-3 fatty acid ratio close to 1, which is favourable for human health. The two seasonal sampling times revealed significant differences in total fatty acid and 20:5 n-3 (EPA) contents, with changes depending on species, thus implying varying suitability as potential target species for EPA production. At both times of the year, Palmaria palmata was identified as most promising species as a source of 20:5 n-3 (EPA) amongst all species investigated, with levels ranging from 0.44 to 0.58 % of dry weight in June and November, respectively.     

Electrospray/tandem mass spectrometry for quantitative analysis of lipid remodeling in essential fatty acid deficient mice

A method utilizing electrospray ionization coupled with tandem mass spectrometry was developed as a facile and rapid method to identify and quantify lipid remodeling in vivo. Electrospray/tandem mass spectrometric analyses were performed on lipids isolated from liver tissue and resident peritoneal cells from essential fatty acid sufficient and deficient mice. Essential fatty acid deficiency was chosen as the paradigm to evaluate the methodology because it epitomizes the most extreme dietary means of altering fatty acid composition of virtually all cellular lipid species. Qualitative and quantitative changes were measured in the phospholipid and cholesterol ester species directly in the chloroform/methanol lipid extract without any prior chromatographic separation. Lipid remodeling in liver and peritoneal cells from essential fatty acid deficient mice was qualitatively similar in cholesterol ester, phosphatidylcholine, and phosphatidylethanolamine. The monoenoic fatty acids palmitoleic acid (16:1 n-7) and oleic acid (18:1 n-9) were increased markedly, whereas all n-6 and n-3 polyunsaturated fatty acids were nearly depleted in phospholipid and cholesterol ester species. The n-9 polyunsaturated fatty acid surrogate, Mead acid (20:3 n-9), substituted for arachidonic acid (20:4 n-6) and docosahexaenoic acid (22:6 n-3) in phospholipid, but not in cholesterol ester, species. Another notable difference was that adrenic acid (22:4 n-6) and docosapentaenoic acid (22:5 n-6), both metabolites of arachidonic acid, accumulated in phospholipid and cholesterol ester species of peritoneal cells, but not in liver cells, of essential fatty acid sufficient mice. The overall body of data presented illustrates the implementation of electrospray/tandem mass spectrometry as a method for facile and direct quantification of changes in lipid species during lipid metabolic studies.     

Utilization of tartaric acid and related compounds by yeasts: taxonomic implications.

A survey of yeasts capable of growing on L(+)-tartaric acid as the sole source of carbon and energy showed that this organic acid is assimilated by a significant number of species of basidiomycetous affinity and is seldom utilized by ascomycetous yeasts. This conclusion was further supported by the fact that among approximately 100 isolates from various natural substrates, using selective media with L(+)-tartaric acid, only one strain of ascomycetous affinity was obtained. In a more comprehensive survey 442 yeast strains belonging to 138 species, mostly of basidiomycetous affinity, were also screened for the assimilation of different aldaric acids: D(-)-tartaric acid, meso-tartaric acid, L(-)-malic acid, D(+)-glucaric acid (saccharic acid), and galactaric acid (mucic acid). L(+)-Tartrate was the most frequently utilized tartaric acid isomer (55% of the total number of strains of basidiomycetous affinity belonging to either the Tremellales/Filobasidiales or the Ustilaginales) when compared with the D(-) and meso forms, which were assimilated by 12 and 18% of the total number of strains, respectively (mainly of tremellaceous species). Saccharic acid was utilized by about 75% of the total number of species of Tremellales affinity and by less than 20% of the ustilaginaceous species. Assimilation of mucic acid occurred in more than 50% of the tremellaceous species and only in 5% of the species related to the Ustilaginales. These tests, not used in standard yeast identification sets, appear to contribute to distinguishing taxa at or above the species level.     

BILIARY BILE ACID COMPOSITION OF THE PHYSETERIDAE (SPERM WHALES)

Abstract: The bile acid composition of bile obtained from the hepatopancreatic ducts of three species of sperm whales (Cetacea: Physeteridae) was investigated. Bile acids were isolated by adsorption chromatography and analyzed by sequential HPLC, SIMS, and GLC-MS. In each species the dominant bile acids were deoxycholic acid (a secondary bile acid formed by bacterial 7α-dehydroxylation of cholic acid), and chenodeoxycholic acid (a primary bile acid) which together composed more than 86% of biliary bile acids in all three species. In Physeter catodon (sperm whale) deoxycholic acid constituted 79%, and in Kogia breviceps (pygmy sperm whale) it was 61% of biliary bile acids. The sperm whale, which differs from other whales in having a remnant of a large intestine, is the second mammal identified to date in which deoxycholic acid is the predominant bile acid. The high proportion of deoxycholic acid indicates that in the Physeteridae, anaerobic fermentation occurs in its cecum, and that bile acids undergo enterohepatic cycling. Also found were minor proportions of cholic acid, as well as bacterial derivatives of chenodeoxycholic acid (ursodeoxycholic acid, lithocholic acid, and the 12β-epimer of allo-deoxycholic acid). Bile acids were conjugated with taurine in all species; however, in the sperm whale ( Physeter ) glycine conjugates were present in trace proportions. The bile acid hydroxylation pattern (12α- but not 6α-hydroxylation), lack of primary 5α- (allo) bile acids, and presence of glycine conjugated bile acids suggests the possibility that sperm whales originated from ancient artiodactyls.     

Characterization of Armillaria spp. from peach orchards in the southeastern United States using fatty acid methyl ester profiling

Limited information is available regarding the composition of cellular fatty acids in Armillaria and the extent to which fatty acid profiles can be used to characterize species in this genus. Fatty acid methyl ester (FAME) profiles generated from cultures of A. tabescens, A. mellea, and A. gallica consisted of 16–18 fatty acids ranging from 12–24 carbons in length, although some of these were present only in trace amounts. Across the three species, 9-cis,12-cis-octadecadienoic acid (9,12-C18:2), hexadecanoic acid (16:0), heneicosanoic acid (21:0), 9-cis-octadecenoic acid (9-C18:1), and 2-hydroxy-docosanoic acid (OH-22:0) were the most abundant fatty acids. FAME profiles from different thallus morphologies (mycelium, sclerotial crust, or rhizomorphs) displayed by cultures of A. gallica showed that thallus type had no significant effect on cellular fatty acid composition (P > 0.05), suggesting that FAME profiling is sufficiently robust for species differentiation despite potential differences in thallus morphology within and among species. The three Armillaria species included in this study could be distinguished from other lignicolous basidiomycete species commonly occurring on peach (Schizophyllum commune, Ganoderma lucidum, Stereum hirsutum, and Trametes versicolor) on the basis of FAME profiles using stepwise discriminant analysis (average squared canonical correlation = 0.953), whereby 9-C18:1, 9,12-C18:2, and 10-cis-hexadecenoic acid (10-C16:1) were the three strongest contributors. In a separate stepwise discriminant analysis, A. tabescens, A. mellea, and A. gallica were separated from one another based on their fatty acid profiles (average squared canonical correlation = 0.924), with 11-cis-octadecenoic acid (11-C18:1), 9-C18:1, and 2-hydroxy-hexadecanoic acid (OH-16:0) being most important for species separation. When fatty acids were extracted directly from mycelium dissected from naturally infected host tissue, the FAME-based discriminant functions developed in the preceding experiments classified all samples (n = 16) as A. tabescens; when applied to cultures derived from the same naturally infected samples, all unknowns were similarly classified as A. tabescens. Thus, FAME species classification of Armillaria unknowns directly from infected tissues may be feasible. Species designation of unknown Armillaria cultures by FAME analysis was identical to that indicated by IGS-RFLP classification with AluI.     

The prostaglandin synthesis in marine fish thrombocyte

1. Prostaglandin (PG) syntheses from labelled highly unsaturated fatty acids were investigated in washed thrombocyte suspensions of four species of marine fish, flounder (Paralichthys olivaceus), black seabream (Acanthopagrus schlegeli), black rockfish (Sebastes schlegeli), and red seabream (Pagrus major). 2. Synthesized PGs were analyzed by thin-layer radiochromatogram scanner and high-performance liquid chromatography. 3. When [1-(14)C]arachidonic acid (AA) was incubated with washer thrombocyte suspension, AA was mainly converted to PGF(2alpha), PGE2, and PGD2 in all species. 4. It was suggested that [1-(14)C]eicosapentaenoic acid was mainly converted in PGs only in black rockfish thrombocytes, and the metabolites were mainly PGE3 and PGD3. 5 However, [1-(14)C]docosahexaenoic acid was not cyclized into PGs in all the species.     

不同物候时期华西雨屏区四个树种新鲜凋落物可提取腐殖质碳动态

凋落物的可提取腐殖质碳可随着植物生长节律及物候时期的变化而变化,并进而影响物质循环的过程,为深入了解以凋落物为载体的生态系统物质循环特征,该研究以华西雨屏区麻栎(Quercus acutissima)、楠木(Phoebe zhennan)、柳杉(Cryptomeria fortune)和喜树(Camptotheca acuminate)为对象,通过定点动态收集萌芽期、展叶期、盛叶期和落叶期的不同类型凋落物,分析其可提取腐殖质碳(extractable humus carbon,HC)、胡敏酸碳(humic acid carbon,HAC)、富里酸碳(fulvic acid carbon,FAC)以及胡敏酸碳/富里酸碳(humic acid carbon/fulvic acid carbon,HAC/FAC)的差异。结果表明:相对于其他凋落器官,在同一物候时期凋落叶中的HC和HAC含量都最高,大致都表现为凋落叶>凋落枝>凋落果,且在落叶树种中更为显著;相对于其他时期,展叶期四个树种凋落叶均表现出较高的FAC含量,但不同物候期凋落枝和凋落果的HAC含量以及FAC含量受物种的影响较大。尽管HAC/FAC在各器官间差异并不显著,但落叶树种相同器官的HAC/FAC低于常绿树种,表明落叶树种凋落物富里酸相对含量较高,形成速度相对较快,难降解程度也相对较大。统计分析表明关键时期、物种类型、器官类型及其相互作用对凋落物中HC、HAC、FAC含量和HAC/FAC均具有不同程度的影响,这为进一步深入认识区域生态系统以凋落物为载体的物质循环过程提供了理论依据及新的思路。     

Metabolic characterization of sciadonic acid (5c,11c,14c-eicosatrienoic acid) as an effective substitute for arachidonate of phosphatidylinositol.

Sciadonic acid (20:3 Delta-5,11,14) is an n-6 series trienoic acid that lacks the Delta8 double bond of arachidonic acid. This fatty acid is not converted to arachidonic acid in higher animals. In this study, we characterized the metabolic behavior of sciadonic acid in the process of acylation to phospholipid of HepG2 cells. One of the characteristics of fatty acid compositions of phospholipids in sciadonic acid-supplemented cells is a higher proportion of sciadonic acid in phosphatidylinositol (PtdIns) (27.4%) than in phosphatidylethanolamine (PtdEtn) (23.2%), phosphatidylcholine (PtdCho) (17.3%) and phosphatidylserine (PtdSer) (20.1%). Similarly, the proportion of arachidonic acid was higher in PtdIns (35.8%) than in PtdEtn (29.1%), PtdSer (18.2%) and PtdCho (20.2%) in arachidonic-acid-supplemented cells. The extensive accumulation of sciadonic acid in PtdIns resulted in the enrichment of newly formed 1-stearoyl-2-sciadonoyl molecular species (38%) in PtdIns and caused the reduction in the level of pre-existing arachidonic-acid-containing molecular species. The kinetics of incorporation of sciadonic acid to PtdEtn, PtdSer and PtdIns of cells were similar to those of arachidonic acid. In contrast to sciadonic acid, neither eicosapentaenoic acid (20:5 Delta-5,8,11,14,17) nor juniperonic acid (20:4 Delta-5,11,14,17) accumulated in the PtdIns fraction. Rather, these n-3 series polyunsaturated fatty acids, once incorporated into PtdIns, tended to be excluded from PtdIns. In addition, the level of arachidonic-acid-containing PtdIns molecular species remained unchanged by eicosapentaenoic-acid-supplementation. These results suggest that sciadonic acid or sciadonic-acid-containing glycerides are metabolized in a similar manner to arachidonic acid or arachidonic-acid-containing glyceride in the biosynthesis of PtdIns and that sciadonic acid can effectively modify the molecular species composition of PtdIns in HepG2 cells. In this regard, sciadonic acid will be an interesting experimental tool to clarify the significance of arachidonic acid-residue of PtdIns-origin bioactive lipids.     

Biosynthesis of triacylglycerol molecular species in an oleaginous fungus,Mortierella ramanniana var. angulispora

The incorporation of radiolabeled lipid precursors into triacylglycerol (TG) molecular species in Mortierella ramanniana var. angulispora, an oleaginous fungus, was studied to determine the biosynthetic pathways for TG molecular species. Radiolabeled TG molecular species were separated and quantified by reverse-phase high performance liquid chromatography with a radioisotope detector. The major TG molecular species labeled by [1-(14)C]oleic acid at 30 degrees C were OOP, OOO, and OPP (TG molecular species designations represent three constituent acyl groups. G, gamma-linolenic acid; L, linoleic acid; O, oleic acid; S, stearic acid; P, palmitic acid), which were abundant TG molecular species in this fungus. The incorporation of [1-(14)C]oleic acid at 15 degrees C into these molecular species was the same, while that into most other species was decreased, suggesting that biosynthesis of major molecular species such as OOP, OOO, and OPP differs from that of other TG molecular species. [1-(14)C]Linoleic acid incorporation indicated that the major labeled molecular species were LOP and LOO, which may be due to acylation of oleoyl, palmitoyl-glycerol, or dioleoyl-glycerol by exogenous linoleic acid. This is basically the same mechanism as for OOP and OOO biosynthesis from exogenous oleic acid. [(14)C(U)]Glycerol incorporation suggested that TG molecular species containing palmitic acid such as OPP were more readily synthesized through the de novo pathway. Further experiments involving inhibitors such as sodium azide and cerulenin suggested that OOO biosynthesis included a mechanism differing from that in the cases of OOP and OPP. Trifluoperazine, which inhibits the conversion from phosphatidic acid to TG, decreased [1-(14)C]oleic acid incorporation into all molecular species, suggesting that the incorporation into all molecular species included the de novo TG biosynthetic pathway via phosphatidic acid. These results revealed that the biosynthetic pathways for TG molecular species can be classified into several groups, which exhibit different sensitivities to low temperature and inhibitors of lipid metabolism. This implies that the composition of TG molecular species is regulated through different biosynthetic pathways responsible for specific TG molecular species, providing a new insight into the biosynthesis of TG molecular species.