-Hydroxy fatty acids in sphingolipids of Tetrahymena

Hydroxy fatty acids in the surface Earth system

Lipids are ubiquitous and highly abundant in a wide range of organisms and have been found in various types of environmental media. These molecules play a crucial role as organic tracers by providing a chemical perspective on viewing the material world, as well as offering a wealth of information on metabolic activities. Among the diverse lipid compounds, hydroxy fatty acids (HFAs) with one to multiple hydroxyl groups attached to the carbon chain stand out as important biomarkers for different sources of organic matter. HFAs are widespread in nature and are involved in biotransformation and oxidation processes in living organisms. The unique chemical and physical properties attributed to the hydroxyl group make HFAs ideal biomarkers in biomedicine and environmental toxicology, as well as organic geochemistry. The molecular distribution patterns of HFAs can be unique and diagnostic for a given class of organisms, including animals, plants, and microorganisms. Thus, HFAs can act as a valuable proxy for understanding the ecological relationships between different organisms and their environment. Furthermore, HFAs have numerous industrial applications due to their higher reactivity, viscosity, and solvent miscibility. This review paper integrates the latest research on the sources and chemical analyses of HFAs, as well as their applications in industrial/medicinal production and as biomarkers in environmental studies. This review article also provides insights into the biogeochemical cycles of HFAs in the surface Earth system, highlighting the importance of these compounds in understanding the complex interactions between living organisms and the environment.

Detection and identification of Bacteriovorax stolpii UKi2 Sphingophosphonolipid molecular species

Bacteriovorax stolpii is a predator of larger gram-negative bacteria and lives as a parasite in the intraperiplasmic space of the host cell. This bacterium is unusual among prokaryotes in that sphingolipids comprise a large proportion of its lipids. We here report the presence of 18 molecular species of B. stolpii UKi2 sphingophosphonolipids (SPNLs). (31)P NMR spectroscopy and analysis of P(i) released by a differential hydrolysis protocol confirmed the phosphonyl nature of these lipids. The SPNLs were dominated by those with 1-hydroxy-2-aminoethane phosphonate (hydroxy-aminoethylphosphonate) polar head groups; aminoethylphosphonate was also detected in minor SPNL components. The long-chain bases (LCBs) were dominated by C(17) iso-branched phytosphingosine; C(17) iso-branched dihydrosphingosine was also present in some SPNLs. The N-linked fatty acids were predominantly iso-branched and most contained an alpha-hydroxy group (C(15) alpha-hydroxy fatty acid was the major fatty acid). Minor molecular species containing nonhydroxy fatty acids were also detected. The definitive iso-structures of the predominant fatty acids and LCBs present in the B. stolpii SPNLs were established using (13)C and (3)H nuclear magnetic resonance spectroscopy; less than 20% were unbranched. Detection and analyses of intact compounds by MS-MS were performed by a hybrid quadrupole time-of-flight (Q-TOF-II) MS equipped with an electrospray ionization source. Analyses of peracetylated derivatives verified the structural assignments of these lipids.

Sphingophosphonolipids, phospholipids, and fatty acids from Aegean jellyfish Aurelia aurita

The goal of this study is to elucidate and identify several sphingophosphonolipids from Aurelia aurita, an abundant but harmless Aegean jellyfish, in which they have not previously been described. Total lipids of A. aurita were 0.031-0.036% of fresh tissue, and the lipid phosphorus content was 1.3-1.7% of total lipids. Phosphonolipids were 21.7% of phospholipids and consisted of a major ceramide aminoethylphosphonate (CAEP-I; 18.3%), as well as three minor CAEP (II, III, IV) methyl analogs at 1.3, 1.1, and 1.0%, respectively. The remaining phospholipid composition was: phosphatidylcholine, 44.5%, including 36.2% glycerylethers; phosphatidylethanolamine, 18.6%, including 4.5% glycerylethers; cardiolipin, 5.6%; phosphatidylinositol, 2.6%; and lysophosphatidylcholine, 5.0%. In CAEP-I, saturated fatty acids of 14-18 carbon chain length were 70.8% and were combined with 57.3% dihydroxy bases and 23.4% trihydroxy bases. The suite of the three minor CAEP methyl analogs were of the same lipid class based on the head group, but they separated into three different components because of their polarity as follows: CAEP-II and CAEP-III differentiation from the major CAEP-I was mainly due to the increased fatty acid unsaturation and not to a different long-chain base, but the CAEP-IV differentiation from CAEP-I, apart from fatty acid unsaturation, was due to the increased content of hydroxyl groups originated from both hydroxy fatty acids and trihydroxy long-chain bases. Saturated fatty acids were predominant in total (76.7%), polar (83.0%), and neutral lipids (67.6%) of A. aurita. The major phospholipid components of A. aurita were comparable to those previously found in a related organism (Pelagia noctiluca), which can injure humans.

A novel sphingophosphonolipid head group 1-hydroxy-2-aminoethyl phosphonate in Bdellovibrio stolpii

Members of the bacterial genus Bdellovibrio include strains that are free-living, whereas others are known to invade and parasitize larger Gram-negative bacteria. The bacterium can synthesize several sphingophospholipid compounds including those with phosphoryl bonds as well as phosphonyl bonds. In the present study, the dominant sphingophosphonolipid component was isolated by column chromatography, and the long-chain bases, fatty acids, and polar head groups were identified by thin-layer and gas-liquid chromatographic procedures. The definitive structural identity of the sphingolipid was established by nuclear magnetic resonance and mass spectrometry of hydrolysis products and the intact compound. The compound was identified as N-2'-hydroxypentadecanoyl-2-amino-3,4-dihydroxyheptadecan-1-phosphono-(1-hydroxy-2-aminoethane).

Phospholipid biosynthesis in protozoa

Because of the diverse nature of the organisms which are all classed as 'protozoa' (and because of the lack of detailed information on phospholipid metabolism about most of them), it will probably never be possible to generalize phospholipid metabolism to the degree that it has been possible to characterize a mammalian metabolism. Nonetheless, patterns have begun to emerge (i.e. the similarities among the ciliates Entodinium, Paramecium and Tetrahymena) and will not doubt be expanded upon in the future.

Metabolism of odd-numbered, normal fatty acids in Tetrahymena pyriformis W

Tetrahymena pyriformis W cells were grown with short- and long-chain, odd and even normal fatty acid supplements. Tris acetate addition had no effect on the fatty acyl composition of the glycerophospholipids or sphingolipids, while Tris propionate supplementation led to a marked increase in odd normal fatty acids at the expense of even normal acids in both classes of complex lipids. This enhancement of odd normal acids permitted the identification of 17:1 delta 9(n), 17:2 delta 6,9(n), 17:2 delta 9,12(n), 17:3 delta 6,9,12(n), 19:1 delta 9(n), 19:2 delta 9,12(n) and 19:3 delta 6,9,12(n) by oxidation with periodate-permanganate and examination of the short-chain fragments. Supplementation with pentadecanoic acid (15:0(n)) led to an increase in the proportions of normal C15, C17 and C19 acids. The increase in C15 acids primarily reflected a rise in 15:0(n), whereas the rise in the levels of C17 and C19 acids was accounted for by an elevation of unsaturated acids. Growth with heptadecanoic acid (17:0(n)) resulted in substantial increases in unsaturated normal C17 and C19 fatty acids, while nonadecanoic acid (19:0(n)) addition led only to an increase in the proportion of unsaturated C19 acids. Retroconversion of these saturated, odd normal long chain fatty acid supplements was limited. Supplementation with arachidic acid (20:0(n)) resulted in only a marginal increase (1.4%) in normal C20 fatty acids of both the glycerophospholipids and the mild alkali labile neutral lipids and provided no evidence that desaturation occurred. The release of 14CO2 from [1-14C]arachidic acid when incubated with the ciliates indicated that this long-chain saturate is accumulated, activated and degraded. Normal C16-C19 saturated fatty acids are substrates for the delta 9 desaturase. The delta 11 isomers arise by chain elongation. Normal C16-C19 delta 9 monoenoic acids are substrates for the delta 12 desaturase. Normal C16-C18 delta 9 monoenes, normal C16-C19 delta 9,12 dienes and 18:1 delta 11(n) are desaturated at the C-6,7 position.

Biochemical studies of the excitable membrane of Paramecium tetraurelia. II. Phospholipids of ciliary and other membranes

The phospholipids of cilia and deciliated bodies of Paramecium tetraurelia were isolated and characterized. 1-alkyl-2-acyl-sn-glycero-3-(2'-aminoethyl) phosphonate (GAEPL), phosphatidylethanolamine, and 1-alkyl-2-acyl-sn-glycero-3-phosphorylcholine (GPC) were the major lipids of Paramecium, and the minor lipids included phosphatidylinositol, cardiolipin, ceramide-(2-aminoethyl) phosphonate (CAEP), ceramide phosphorylethanolamine (COPE) and four sphingolipids whose identity was not established. The deciliated bodies contained 4% cardiolipin, 15% GAEPL, 41% phosphatidylethanolamine, 30% GPC and 3% each of CAEP and phosphatidylinositol; the cilia contained no cardiolipin, 24% GAEPL, 37% phosphatidylethanolamine, 15% GPC, 15% CAEP, 3% phosphatidylinositol, 2% COPE and small amounts (approx. 1%) of the four uncharacterized sphingolipids. No alteration in phospholipid composition was found among cells harvested in the various stages of growth. The phospholipids of six Paramecium mutants of three distinct phenotypes (pawn, paranoiac and fast) were also examined. Only one significant difference was found on comparison of the whole cell, deciliated body and cilia fraction of the mutants with the analogous fractions from wild type cells: the fast mutant, fA 97, had two extra, minor phospholipids (approx. 2%) in the deciliated body fraction that were tentatively identified as 1,2-diacyl-sn-glycero-3-(2'-aminoethyl) phosphonate (AEPL) and 1-alkyl-2-acyl-sn-glycero-3-phosphorylethanolamine (GPE).

The effects of isovalerate supplementation on growth and fatty acid composition of Tetrahymena pyriformis W

Cultures of Tetrahymena pyriformis W respond to isovalerate supplementation by an increase in odd-numbered saturated, unsaturated and alpha-hydroxy iso-fatty acids and by a decrease in even-numbered normal fatty acids in the glycerolipids and sphingolipids. Supplementation, however, did not alter the relative amount of unsaturated fatty acids found in the polar lipids. The unsaturated acids 17 : 1(i) and 19 : 1(i) were isolated from cells grown with [1-14C]isovalerate and found to have a higher specific activity than the monoenes of the normal series. Isotopic and gas-chromatographic analyses also indicated the presence of dienoic and trienoic acids of the iso-acid series. The iso-fatty acid content was elevated with isovalerate levels up to 5.0 mM and an inhibition of growth was noted. At higher concentrations of the short chain precursor, no further increase in total cellular iso-acids was detected although growth inhibition was more pronounced. The alpha-hydroxy iso-fatty acids of the sphingolipids, however, were elevated in a fashion that paralleled the external concentration of isovalerate; thus, the amount of alpha-hydroxy iso-acids and the degree of growth inhibition show a direct relationship. The increase in alpha-hydroxy iso-acid content of the sphingolipids was at the expense of the saturated normal and iso-acid components. The impact on the physiology of the cells can be envisaged as the result of changes in membrane fluidity due to the presence of high levels of iso-fatty acids without an accompanying reduction in unsaturated acids.