Incorporation and modification of dietary fatty acids in gill polar lipids by two bivalve species Crassostrea gigas and Ruditapes philippinarum

Two bivalve species Crassostrea gigas and Ruditapes philippinarum were fed eight weeks with three mono-specific algae diets: T-Isochrysis galbana, Tetraselmis suecica, Chaetoceros calcitrans, selected on the basis of their polyunsaturated fatty acid (PUFA) composition. The incorporation and the modification of dietary fatty acids in C. gigas and R. philippinarum gill lipids were analysed and compared. Essential PUFA (20:4n-6, 20:5n-3 and 22:6n-3) and non-methylene interrupted PUFAs (known to be synthesised from monounsaturated precursors) contents of gill polar lipid of both species were greatly influenced by the dietary conditioning. Interestingly, oysters and clams responded differentially to the mono-specific diets. Oysters maintained higher 20:5n-3 level and higher 22:2j/22:i and n-7/n-9 ratio in gill polar lipids than clams. To better discriminate dietary and species influences on the fatty acid composition, a Principal Component Analysis followed by a MANOVA on the two most explicative components was performed. These statistical analyses showed that difference in fatty acid compositions attributable to species were just as significant as the diet inputs. The differences of gill fatty acid compositions between oysters and clams are speculated to result of an intrinsic species characteristic and perhaps of a group characteristic: Fillibranch vs. Eulamellibranch.     

Effect of diet on fatty acid compositions in Sciaenops ocellatus

The role of dietary polyunsaturated fatty acids (PUFAs) on the fatty acid composition of juvenile red drum Sciaenops ocellatus was investigated. Individuals (n = 435) were fed three natural diets (Gulf menhaden Brevoortia patronus, brown shrimp Farfantapenaeus aztecus and Atlantic brief squid Lolliguncula brevis) that had significantly different proximate composition, energy density and PUFA compositions for 40 days. Diets were characterized as containing: high lipid, high protein, high energy and low PUFA (fish‐based), low lipid, low protein, low energy, moderate PUFA (shrimp‐based), and low lipid, high protein, moderate energy and high PUFA levels (squid‐based), respectively. Specimens were collected at days 0, 5, 10, 20 and 40 to evaluate rate of dietary fatty acid composition in tissues. Two‐source mixing models were used to calculate dietary fatty acid accumulation in consumer tissues. Results indicated that juvenile red drum incorporated an average of 35% dietary PUFAs after 5 days. Although relative biomass and dietary proximate composition had an effect upon the dietary fatty acid contribution, red drum averaged 91% incorporation of the five most prevalent PUFAs [18 : 2 (n ? 6), 20 : 4 (n ? 6), 20 : 5 (n ? 3), 22 : 5 (n ? 3) and 22 : 6 (n ? 3)] across all diets after 40 days. Growth varied as a function of diet and rates were higher for individuals fed the squid diet than those fed shrimp or fish diets primarily due to increased levels of protein and PUFAs [including 22 : 6 (n ? 3); 25·8%] in the diet. Red drum fed squid exhibited the greatest increase in average dietary fatty acid contribution by day 5, a trend that continued for the duration of the experiment. Since PUFA composition in red drum was significantly influenced by diet in as few as 5 days and almost completely incorporated into body tissues after 40 days, results from this study support the premise that fatty acids (especially PUFAs) are promising dietary indicators and may be useful for future studies examining trophic relationships of estuarine and marine fishes.     

Cloning and functional expression of the first plant fatty acid elongase specific for Delta(6)-polyunsaturated fatty acids

In order to elucidate the biosynthesis of long-chain polyunsaturated fatty acids (PUFAs) in plants we searched for a cDNA encoding a Delta(6)-specific PUFA elongase from Physcomitrella patens, which is known to contain high proportions of arachidonic acid (20:4 Delta(5,8,11,14)). An EST clone from P. patens was identified by its low homology to the yeast gene ELO1, which is required for the elongation of medium-chain fatty acids. We functionally characterized this cDNA by heterologous expression in Saccharomyces cerevisiae grown in the presence of several fatty acids. Analysis of the fatty acid profile of the transgenic yeast revealed that the cDNA encodes a protein that leads to the elongation of the C(18) Delta(6)-polyunsaturated fatty acids gamma-linolenic acid (18:3 Delta(6,9,12)) and stearidonic acid (18:4 Delta(6,9,12,15)), which were recovered to 45-51% as their elongation products. In contrast, linoleic and alpha-linolenic acids were hardly elongated and we could not measure any elongation of saturated and mono-unsaturated fatty acids (including 18:1 Delta(6)), indicating that the elongase is highly specific for the polyunsaturated nature of the fatty acid acting as substrate.     

The Use of Neutral Lipid Fatty Acids to Indicate the Physiological Conditions of Soil Fungi

The usefulness of measuring neutral lipid fatty acids (NLFAs) and phospholipid fatty acids (PLFAs) separately in order to interpret perturbation effects on soil and compost microorganisms has been studied. Initially the NLFA/PLFA ratios were studied in different soils. Low ratios were found for fatty acids common in bacteria, especially for cyclopropane fatty acids. Higher ratios were found for fatty acids common in eukaryotic organisms such as fungi (18:1omega9 and 18:2omega6,9) or in saturated fatty acids, common to many types of organisms. Adding glucose to a forest soil increased the amounts of the fungal NLFAs 18:1omega9 and 18:2 omega6,9 up to 60 and 10 times, respectively, after 10 days, followed by a gradual decrease. After 3 months incubation, higher levels of these NLFAs were still found compared with the control samples. Adding glucose together with nitrogen (N) and phosphorus (P) resulted in no increase in NLFAs but a 10-fold increase in the PLFAs 18:1omega9 and 18:2omega6,9. Thus, the NLFA/PLFA ratios for these fatty acids were lower than in the no-addition control when glucose was added together with N and P, but higher when glucose was added alone, even 3 months after the addition. Adding N+P without glucose did not affect the NLFA/PLFA ratio for any fatty acid. Increasing NLFA/PLFA ratios for the fungal fatty acids were also found with time after the thermophilic phase in a compost, indicating increased availability of easily available carbon.     

Temperature affects the limitation of Daphnia magna by eicosapentaenoic acid,and the fatty acid composition of body tissue and eggs

1. Poikilothermic animals incorporate more polyunsaturated fatty acids (PUFAs) into their cellular membranes as temperature declines, suggesting an increased sensitivity to PUFA limitation in cool conditions. To test this we raised Daphnia magna at different temperatures and investigated the effect of varying dietary PUFA on life history parameters (i.e. growth, reproduction) and the PUFA composition of body tissue and eggs. 2. Upon a PUFA‐rich diet (Cryptomonas sp.) females showed higher concentrations of several ω3 PUFAs in their body tissue at 15 °C than at 20 °C and 25 °C, indicating a greater structural requirement for ω3 PUFAs at low temperature. Their eggs had an equal but higher concentration of ω3 PUFAs than their body tissue. 3. In a life history experiment at 15 and 20 °C we supplemented a diet of a PUFA‐free cyanobacterium with the ω3 PUFA eicosapentaenoic acid (EPA). The growth of D. magna was more strongly EPA limited at low temperature. A greater requirement for structural EPA at 15 °C was indicated by a steeper increase in somatic EPA content with dietary EPA compared to 20 °C. 4. At 20 °C the development of eggs to successful hatching was high when EPA was supplied to the mothers. At 15 °C the hatching success was generally poor, despite of a higher maternal provision of EPA to eggs, compared to that at 20 °C, suggesting that EPA alone was insufficient for proper neonatal development at the low temperature. The growth of offspring from mothers raised at 20 °C without EPA supplementation was very low, indicating that the negative effects of EPA deficiency can be carried on to the next generation. 5. The fatty acid composition of Daphnia sp. in published field studies shows increasing proportions of saturated fatty acids with increasing environmental temperature, whereas ω3 PUFAs and EPA show no clear pattern, suggesting that variations in dietary PUFA may mask temperature‐dependent adjustments in ω3 PUFA concentrations of cladocerans in nature.     

Tissue-Specific Fatty Acids Response to Different Diets in Common Carp (Cyprinus carpio L.)

Fish depend on dietary fatty acids (FA) to support their physiological condition and health. Exploring the FA distribution in common carp (Cyprinus carpio), one of the world''s most consumed freshwater fish, is important to understand how and where FA of different sources are allocated. We investigated diet effects on the composition of polar and neutral lipid fatty acids (PLFA and NLFA, respectively) in eight different tissues (dorsal and ventral muscle, heart, kidney, intestine, eyes, liver and adipose tissue) of common carp. Two-year old carp were exposed to three diet sources (i.e., zooplankton, zooplankton plus supplementary feeds containing vegetable, VO, or fish oil, FO) with different FA composition. The PLFA and NLFA response was clearly tissue-specific after 210 days of feeding on different diets. PLFA were generally rich in omega-3 polyunsaturated FA and only marginally influenced by dietary FA, whereas the NLFA composition strongly reflected dietary FA profiles. However, the NLFA composition in carp tissues varied considerably at low NLFA mass ratios, suggesting that carp is able to regulate the NLFA composition and thus FA quality in its tissues when NLFA contents are low. Finally, this study shows that FO were 3X more retained than VO as NLFA particularly in muscle tissues, indicating that higher nutritional quality feeds are selectively allocated into tissues and thus available for human consumption.     

Effect of dietary fatty acids on the body tissues of larval and juvenile cobia and their prey

Polyunsaturated fatty acids (PUFAs) have been used as biomarkers in pelagic ecosystems although previous studies have failed to quantify the timing of conservation of dietary PUFAs in pelagic fishes and invertebrates. Here we investigated the influence of diet upon the timing of conservation of PUFAs throughout multiple trophic exchanges in larval and juvenile cobia (Rachycentron canadum) and their prey. Cobia, rotifers (Brachionus plicatilis), and Artemia (A. franciscana) were fed laboratory processed or natural diets resembling prey and dietary modification of fatty acid signatures was quantified using two-source mixing models. Specimens were collected throughout the experiment to track dietary influences over time. Cobia larvae underwent significant dietary modification of PUFAs after 24 h and conserved > 90% of dietary PUFAs after an average of 6 days. Similar results were identified in juvenile cobia as significant dietary modification of PUFAs took place after 3 days and > 90% were conserved after an average of 12 days. In addition, no significant ontogenetic changes in PUFA signatures were identified in juvenile cobia throughout the 30-day experiment. PUFA signatures in prey items (rotifers and Artemia) underwent significant dietary modification in 24 h, with over 90% incorporation after 5-7 days. Results from this study support the premise that fatty acids are promising dietary indicators and may be useful for future studies examining trophic relationships in marine ecosystems and habitat use of marine fishes.     

Contrasting effects of membrane enrichment with polyunsaturated fatty acids on phospholipid composition and cholesterol efflux from cholesterol-loaded J774 mouse or primary human macrophages

A high consumption of polyunsaturated fatty acids (PUFAs), particularly n-3 PUFAs, is atheroprotective. PUFAs incorporation into membrane phospholipids alters the functionality of membrane proteins. We studied the consequences of the in vitro supplementation of several PUFAs on the FA profiles and on ABCA1-dependent cholesterol efflux capacities from cholesterol-loaded macrophages. Arachidonic acid (AA, C20:4 n-6) and, to a lesser extent, eicosapentaenoic acid (EPA, C20:5 n-3), dose-dependently impaired cholesterol efflux from cholesterol-loaded J774 mouse macrophages without alterations in ABCA1 expression, whereas docosahexaenoic acid (DHA, C22:6 n-3) had no impact. AA cells exhibited higher proportions of arachidonic acid and adrenic acid (C22:4 n-6), its elongation product. EPA cells exhibited slightly higher proportions of EPA associated with much higher proportions of docosapentaenoic acid (C22:5 n-3), its elongation product and with lower proportions of AA. Conversely, both EPA and DHA and, to a lesser extent, AA decreased cholesterol efflux from cholesterol-loaded primary human macrophages (HMDM). The differences observed in FA profiles after PUFA supplementations were different from those observed for the J774 cells. In conclusion, we are the first to report that AA and EPA, but not DHA, have deleterious effects on the cardioprotective ABCA1 cholesterol efflux pathway from J774 foam cells. Moreover, the membrane incorporation of PUFAs does not have the same impact on cholesterol efflux from murine (J774) or human (HMDM) cholesterol-loaded macrophages. This finding emphasizes the key role of the cellular model in cholesterol efflux studies and may partly explain the heterogeneous literature data on the impact of PUFAs on cholesterol efflux.     

The growth of external AM fungal mycelium in sand dunes and in experimental systems

We estimated the biomass and growth of arbuscular mycorrhizal (AM) mycelium in sand dunes using signature fatty acids. Mesh bags and tubes, containing initially mycelium-free sand, were buried in the field near the roots of the dune grass Ammophila arenaria L. AM fungal mycelia were detected at a distance of about 8.5 cm from the roots after 68 days of growth by use of neutral lipid fatty acid (NLFA) 16:1ω5. The average rate of mycelium extension during September and October was estimated as 1.2 mm day⁻¹. The lipid and fatty acid compositions of AM fungal mycelia of isolates and from sand dunes were analysed and showed all to be of a similar composition. Phospholipid fatty acids (PLFAs) can be used as indicators of microbial biomass. The mycelium of G. intraradices growing in glass beads contained 8.3 nmol PLFAs per mg dry biomass, and about 15% of the PLFAs in G. intraradices, G. claroideum and AM fungal mycelium extracted from sand dunes, consisted of the signature PLFA 16:1ω5. We thus suggest a conversion factor of 1.2 nmol PLFA 16:1ω5 per mg dry biomass. Calculations using this conversion factor indicated up to 34 μg dry AM fungal biomass per g sand in the sand dunes, which was less than one tenth of that found in an experimental system with Glomus spp. growing with cucumber as plant associate in agricultural soil. The PLFA results from different systems indicated that the biomass of the AM fungi constitutes a considerable part of the total soil microbial biomass. Calculations based on ATP of AM fungi in an experimental growth system indicated that the biomass of the AM fungi constituted approximately 30% of the total microbial biomass. This revised version was published online in June 2006 with corrections to the Cover Date.     

Effect of culture media and conditions on polyunsaturated fatty acids production by Mortierella alpina

To improve the polyunsaturated fatty acid (PUFA) production by Mortierella, culture media and conditions were investigated. M. alpina ATCC 32222 had the highest yield of arachidonic acid, gamma-linolenic acid and linoleic acid among 11 test microbes. Soluble starch at 10% and the mixture of KNO3 and yeast extract at 2:1 (w/w) was the best carbon and nitrogen sources for arachidonic acid and total PUFAs production, respectively. The optimal C/N ratio ranged from 5.1 to 9.0. Each gram of carbon produced 17.4 mg of linoleic acid, 17.0 mg of gamma-linolenic acid, 103.0 mg of arachidonic acid and 194.2 mg of total PUFAs at 20 degrees C, while it yielded 21.4 mg of linoleic acid, 25.6 mg of gamma-linolenic acid, 2.6 mg of gamma-linolenic acid, 110.3 mg of arachidonic acid, 4.3 mg of eicosapentaenoic acid and 218.4 mg of total PUFAs at 12 degrees C. A high degree of unsaturation was found at low temperature incubation. Linseed oil supplementation (1%, w/v) increased the PUFAs production and each gram of carbon produced 403.4 mg of alpha-linolenic acid, 123.1 mg of arachidonic acid, 33.6 mg of eicosapentaenoic acid, 1.68 mg of docosahexaenoic acid and 943.2 mg of total PUFAs. From the optimization of culture media and conditions, PUFAs production increased from 30% to 5 times that was optimal for practical use.     

Dietary omega-3 and omega-6 polyunsaturated fatty acids modulate hepatic pathology

Recent evidence has suggested that dietary polyunsaturated fatty acids (PUFAs) modulate inflammation; however, few studies have focused on the pathobiology of PUFA using isocaloric and isolipidic diets and it is unclear if the associated pathologies are due to dietary PUFA composition, lipid metabolism or obesity, as most studies compare diets fed ad libitum. Our studies used isocaloric and isolipidic liquid diets (35% of calories from fat), with differing compositions of omega (ω)-6 or long chain (Lc) ω-3 PUFA that were pair-fed and assessed hepatic pathology, inflammation and lipid metabolism. Consistent with an isocaloric, pair-fed model we observed no significant difference in diet consumption between the groups. In contrast, the body and liver weight, total lipid level and abdominal fat deposits were significantly higher in mice fed an ω-6 diet. An analysis of the fatty acid profile in plasma and liver showed that mice on the ω-6 diet had significantly more arachidonic acid (AA) in the plasma and liver, whereas, in these mice ω-3 fatty acids such as eicosapentaenoic acid (EPA) were not detected and docosahexaenoic acid (DHA) was significantly lower. Histopathologic analyses documented that mice on the ω-6 diet had a significant increase in macrovesicular steatosis, extramedullary myelopoiesis (EMM), apoptotic hepatocytes and decreased glycogen storage in lobular hepatocytes, and hepatocyte proliferation relative to mice fed the Lc ω-3 diet. Together, these results support PUFA dietary regulation of hepatic pathology and inflammation with implications for enteral feeding regulation of steatosis and other hepatic lesions.     

A modified <Emphasis Type="Italic">n</Emphasis>–3 fatty acid desaturase gene from <Emphasis Type="Italic">Caenorhabditis briggsae</Emphasis> produced high proportion of DHA and DPA in transgenic mice

The functions of polyunsaturated fatty acids (PUFAs) have been widely investigated. In mammals, levels of n-3 PUFAs are relatively low compared to those of n-6 PUFAs. Either a lack of n-3 PUFAs or an excess of n-6 PUFAs could potentially cause health problems in humans. Hence, methods to increase the amount of n-3 PUFAs in diet have been intensely sought. In this study, we demonstrated that the n-3 fatty acid desaturase gene (sFat-1) synthesized from revised and optimized codons based on roundworm Caenorhabditis briggsae genomic gene for enhanced expression in mammals was successfully expressed in Chinese hamster ovary (CHO) cells and significantly elevated cellular n-3 PUFA contents. We generated sFat-1 transgenic mice by introducing mammal expression vector DNAs containing the sFat-1 gene into regular mice through the method of microinjection. Fatty acid compositions were then altered and the levels of docosahexaenoic acid (DHA, 22:6n-3) and docosapentaenoic acid (DPA, 22:5n-3) were greatly increased in these transgenic mice. Various types of tissues in the transgenic mice produced many types of n-3 PUFAs, such as alpha-linolenic acid (ALA; 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), DPA, and DHA, for example, muscle tissues of the transgenic mice contained 12.2% DHA, 2.0% DPA, and 23.1% total n-3 PUFAs. These research results demonstrated that the synthesized sFat-1 gene with modified and optimized codons from C. briggsae possess functional activity and greater capability of producing n-3 PUFAs, especially DHA and DPA, in transgenic mice.     

Effects of dietary polyunsaturated fatty acid deficiencies on mortality, growth and gill structure in the turbot, Scophthalmus maximus

The preparation of fish oil concentrates containing only ( n -3) polyunsaturated fatty acids (PUFA) with different ratios of 20:5 ( n -3)/22:6 ( n -3) is described. Three groups of turbot were maintained on different diets containing: 1, 10% of the dry weight of the diet as natural fish oil, equivalent to 2.5% ( n -3) PUFA and 0–23% ( n -6) PUFA; 2, 10% of the dry weight of the diet as palmitic acid, i.e. no PUFA; 3, 8–7% palmitic acid and 1–3% of the dry weight as ( n -3 PUFA and negligible ( n -6) PUFA. Only the fish on the diet containing natural fish oil showed significant growth over a 15-week period. In addition there were high mortalities on the two experimental diets (2 and 3). Changing the ratio of 20:5 ( n -3)/22:6 ( n -3) from 13–8 to 2–2 in the diet containing 1 3% (n-3) PUFA and negligible ( n -6) PUFA markedly decreased the mortalities. Fish fed the two experimental diets (2 and 3) developed gross changes in gill structure involving the disappearance of chloride cells, a 'sloughing off' of the epithelium along the primary and secondary filaments and an accumulation of cellular material in the inter-lamellar spaces. The tissue ultimately disintegrated to leave a skeleton of connective tissue and a mass of cellular material in the inter-lamellar spaces. It is concluded that 22:6 (n-3) is an essential fatty acid for turbot and that the gill epithelium is a sensitive indicator of this deficiency in this species.     

Cold acclimation and lipid composition in the earthworm Dendrobaena octaedra

We have investigated the lipid chemistry during cold acclimation in the freeze tolerant earthworm Dendrobaena octaedra. The dominant phospholipid fatty acids (PLFA) of D. octaedra were 20:4, 20:5 and 20:1 (50% of total PLFA) followed by 18:0, 18:1 and 18:2omega6,9 (25% of total PLFA). The ability to tolerate freezing in this species was acquired after acclimation at low temperature for 2-4 weeks. During this period one particular membrane PLFA, 18:2omega6,9, increased significantly and there was a good correlation between the proportion of this PLFA and the survival of freezing. The composition of neutral lipid fatty acids (NLFA), most likely representing storage lipids (triacylglycerides), also changed during cold acclimation so that the overall degree of unsaturation increased. Using a common-garden experiment approach, we compared lipid composition of three genetically different populations (Denmark, Finland and Greenland) that differed in their freeze tolerance. Inter-populational differences and differences due to cold acclimation in overall fatty acid composition were evident in both PLFAs and NLFAs. Specifically, the PLFAs, 20:4 and 20:5, were considerably more represented in worms from Greenland, and this contributed to a higher UI of PLFAs in this population.     

Brain anticonvulsant protection of mice given chronic carbamazepine under various fatty acid and magnesium diet conditions

The anticonvulsant and mood stabilizer drug carbamazepine (CBZ) was evaluated for anti-seizure activity after drug pretreatment of young weaning mice given various oil-based diets. These diets had various mono-(MUFA) and poly-(PUFA) unsaturated fatty acid contents, were associated or not with magnesium deprivation, and were given over the entire experimental period (34 days). The diets included a commercial and three purified synthetic diets (n-6 PUFA, n-3 PUFA and MUFA-based chows containing 5% corn/sunflower oils 1:3, 5% rapeseed oil and 5% high oleic acid sunflower oil/sunflower oil 7:3, respectively). A 10-days CBZ treatment (50mg/kg/day fragmented in two daily intraperitoneal injections of 25mg/kg) was given 20 days after initiating diet administration and evaluations of mice was performed 4 days after arrest of CBZ in various seizure tests. In these conditions, CBZ pretreatment still exhibited anticonvulsant protection especially in magnesium-deficient animals. Ethosuximide (ESM)-like profiles under MUFA and n-3 PUFA diets and unusual GABA(A)ergic profile under n-6 PUFA diet in magnesium-deficiency dependent audiogenic seizures (MDDAS) test as well as protection against NMDA-induced seizures in all lipid (n-3 PUFA>MUFA and n-6 PUFA) diet conditions were observed in CBZ-pretreated mice. By highlighting ESM-like and anti-NMDA mechanisms previously induced by an n-3 PUFA diet, present CBZ anticonvulsant properties suggest brain protective targets common to CBZ and n-3 PUFAs.     

Small amounts of isotope-reinforced polyunsaturated fatty acids suppress lipid autoxidation

Polyunsaturated fatty acids (PUFAs) undergo autoxidation and generate reactive carbonyl compounds that are toxic to cells and associated with apoptotic cell death, age-related neurodegenerative diseases, and atherosclerosis. PUFA autoxidation is initiated by the abstraction of bis-allylic hydrogen atoms. Replacement of the bis-allylic hydrogen atoms with deuterium atoms (termed site-specific isotope-reinforcement) arrests PUFA autoxidation due to the isotope effect. Kinetic competition experiments show that the kinetic isotope effect for the propagation rate constant of Lin autoxidation compared to that of 11,11-D(2)-Lin is 12.8 ± 0.6. We investigate the effects of different isotope-reinforced PUFAs and natural PUFAs on the viability of coenzyme Q-deficient Saccharomyces cerevisiae coq mutants and wild-type yeast subjected to copper stress. Cells treated with a C11-BODIPY fluorescent probe to monitor lipid oxidation products show that lipid peroxidation precedes the loss of viability due to H-PUFA toxicity. We show that replacement of just one bis-allylic hydrogen atom with deuterium is sufficient to arrest lipid autoxidation. In contrast, PUFAs reinforced with two deuterium atoms at mono-allylic sites remain susceptible to autoxidation. Surprisingly, yeast treated with a mixture of approximately 20%:80% isotope-reinforced D-PUFA:natural H-PUFA are protected from lipid autoxidation-mediated cell killing. The findings reported here show that inclusion of only a small fraction of PUFAs deuterated at the bis-allylic sites is sufficient to profoundly inhibit the chain reaction of nondeuterated PUFAs in yeast.     

Unusual medium-chain polyunsaturated fatty acids from the snow alga Chloromonas brevispina

The gas chromatography-mass spectrometry (GC-MS) method was used to identify unusual medium-chain polyunsaturated fatty acids (PUFAs) in the snow alga Chloromonas brevispina collected in 2006 from surface layers of a snow field with conspicuous green patches in Bohemian Forest (Czech Republic). PUFAs formed more than 75% total fatty acids. Among them, mass spectroscopy of picolinyl esters showed sizable proportions of medium-chain PUFA, e.g., 5,8,11-tetradecatrienoic and 6,9,12-pentadecatrienoic acids. The high relative content of PUFA indicates that PUFA are an important element ensuring cell survival. Our report appears to be the first to describe the presence of short- and medium-chain PUFAs in green psychrophilic algae of the genus Chloromonas.     

Specific polyunsaturated fatty acids drive TRPV-dependent sensory signaling in vivo

A variety of lipid and lipid-derived molecules can modulate TRP cation channel activity, but the identity of the lipids that affect TRP channel function in vivo is unknown. Here, we use genetic and behavioral analysis in the nematode C. elegans to implicate a subset of 20-carbon polyunsaturated fatty acids (PUFAs) in TRPV channel-dependent olfactory and nociceptive behaviors. Olfactory and nociceptive TRPV signaling are sustained by overlapping but nonidentical sets of 20-carbon PUFAs including eicosapentaenoic acid (EPA) and arachidonic acid (AA). PUFAs act upstream of TRPV family channels in sensory transduction. Short-term dietary supplementation with PUFAs can rescue PUFA biosynthetic mutants, and exogenous PUFAs elicit rapid TRPV-dependent calcium transients in sensory neurons, bypassing the normal requirement for PUFA synthesis. These results suggest that a subset of PUFAs with omega-3 and omega-6 acyl groups act as endogenous modulators of TRPV signal transduction.     

Fatty acid composition of the cold-water-inhabiting freshwater red alga Sirodotia Kylin

Four samples of freshwater alga Sirodotia (class Rhodophyceae) collected from two distinct streams in the Mahabaleshwar, Satara district (1,732 m a.s.l.) of the Western Ghats of Maharashtra (India) were analysed for their fatty acid content. The presence of 32 fatty acids was revealed, of which 13 were saturated (SFA), 8 were monounsaturated (MUFA) and 11 were polyunsaturated (PUFA) fatty acids. The major finding was the presence of three pharmaceutically and neutraceutically important PUFAs: arachidonic acid (AA), eicosapentanoeic acid (EPA), and docosahexanoiec acid (DHA). The major fatty acids identified were palmitic (16:0), cis-11,14 icodienoic (20:2), behenic (22:0), cis-8,11,14 eicosatrienoic(20:3n6), cis-4,7,10,13,16,19 docosahexanoeic (22:6n3), cis-13,16 docosadienoic (22:2), erucic (22:1n9), -5,8,11,14,17 eicosapentaenoic (20:5n3), trichosonoic (23:0), nervonic (24:0), arachidonic (20:4n6), cis-10 pentadecanoic (15:1), cis-11,14,17 eicosatrienoic (20:3n3), and myristic acid (14:0). The total PUFA contents ranged from 31.45 to 40.37%. The fatty acids were characterised by the relatively high abundance of PUFAs, while C20 unsaturated acids were appreciably more abundant than C18 unsaturated acids. This is the first report on fatty acid profiles of the genus Sirodotia.