Dienoic Fatty Acids Research Articles

Жирнокислотный состав и активность ацил-липидных десатураз в почках березы повислой в зимне-весенний период в Карелии и Якутии

The dynamics of the fatty acid composition and activity of acyl-lipid desaturases contained in the buds of silver birch Betula pendula Roth have been studied. The places of growth of this tree are located in contrasting natural and climatic conditions: at the same latitude – 62° N, but are separated from each other by more than 5 thousand km in the longitudinal direction – 34° E (the vicinity of Petrozavodsk) and 130° E (the vicinity of Yakutsk). It has been found that, regardless of the place of growth, in the spring-winter period, the total lipids of the buds of silver birch have been characterized by a high content of unsaturated fatty acids. At the same time, significant differences have been revealed in the composition of mono-, di- and trienoic fatty acids, the dynamics of which have largely depended on both the phase of winter-spring plant development and the degree of continentality of the climate. It has been shown that in Karelia, during the exogenous dormancy period (January–March), an increased content of dienoic fatty acids is observed in the lipids of the buds of silver birch, and by the beginning of their breaking (April–May) – trienoic fatty acids, whereas in Yakutia in the winter-spring period monoenoic and dienoic fatty acids steadily prevail. At the same time, a high activity of ω6- and ω3-desaturases (responsible for the synthesis of linoleic С18:2 and С18:3 fatty acids) has been detected in the lipids of the buds of silver birch growing in Karelia, and ω9-desaturase (catalyzing the synthesis of oleic С18:1 fatty acid) in Yakutia. It has been suggested that in permafrost conditions there is a relationship between the expression of genes controlling the formation of ω9-acyl-lipid desaturase and the resistance of the tissues of primordial organs during their intra-bud development to negative temperatures not only of the air, but also of the root-inhabited soil layer. The authors believe that the features identified in the composition of total lipids in the buds of silver birch in Yakutia compared to Karelia can be considered as one of the additional mechanisms that increase the adaptive potential of the species in permafrost conditions and allowing the representatives of the genus Betula L. to expand their area to the northern limit of the distribution of woody vegetation.

Sexual dimorphism in the gonad lipidome of blue mussels (Mytilus sp.): New insights from a global lipidomics approach

Blue mussels (Mytilus sp.) are an economically important species for European aquaculture. Their importance as a food source is expected to increase in the coming net-zero society due to their low environmental footprint; however, their production is affected by anthropogenic stressors and climate change. During reproduction, lipids are key molecules for mussels as they are the main source of energy on which newly hatched embryos depend in the first days of their development. In this work, blue mussels of different origins are analysed, focusing on the differences in lipid composition between the ovary (BMO) and the testis (BMT). The lipidome of blue mussel gonads (BMG) is studied here by combining traditional lipid profiling methods, such as fatty acid and lipid class analysis, with untargeted liquid chromatography-mass spectrometry (LC-MS) lipidomics. The approach used here enabled the identification of 770 lipid molecules from 23 different lipid classes in BMG. BMT, which consists of billions of spermatocytes, had greater amounts of cell membrane and membrane lipid components such as FA18:0, C20 polyunsaturated fatty acids (PUFA), free sterols (ST), ceramide phosphoethanolamines (CerPE), ceramide aminoethylphosphonates (CAEP), cardiolipins (CL), glycerophosphocholines (PC), glycerophosphoethanolamines (PE) and glycerophosphoserines (PS). In BMO, saturated fatty acids (FA14:0 and FA16:0), monounsaturated fatty acids (MUFA) and other storage components such as C18-PUFA accumulated in triradylglycerolipids (TG) and alkyldiacylglycerols (neutral plasmalogens, TG O-), which, together with terpenes, wax esters and cholesterol esters, make up most of oocytes yolk reserves. BMO also had higher levels of ceramides (Cer) and generally alkyl/alkenyl glycerophospholipids (mainly plasmanyl/plasmenyl PC), suggesting a role for these lipids in vitellogenesis. Non-methylene interrupted dienoic fatty acids (NMID FA), typically found in plasmalogens, were the only membrane-forming PUFA predominantly detected in BMO. The results of this study are of great importance for clarifying the lipid composition of BMG and provide an important basis for future studies on the reproductive physiology of these organisms.

Acyl-Lipid Δ6-Desaturase May Act as a First FAD in Cyanobacteria.

Fatty acid desaturases (FADs) play important roles in various metabolic and adaptive pathways in all living organisms. They represent a superfamily of oxygenases that introduce double bonds into the acyl chains of fatty acids (FAs). These enzymes are highly specific to the length of the carbon chain, position of double bonds formation, etc. The modes by which FADs "count" the position of the double bond formation may differ. In cyanobacteria, the first double bond is formed between 9th and 10th carbons (position Δ9), counting from the carboxylic end of an FA. Other FADs that produce polyunsaturated FAs may introduce double bonds counting from the carboxyl (Δ) or methyl (ω) terminus, or from a pre-existing double bond towards carboxyl or methyl terminus of an FA chain. Here, we expressed the desD gene for the Δ6-FAD from Synechocystis sp. PCC 6803 in Synechococcus elongatus PCC 7942 (which is capable of synthesizing only monoenoic FAs desaturated mainly at position Δ9) and observed the appearance of unusual monoenoic FAs desaturated at position Δ6, as well as Δ6,9 dienoic FAs. Exogenously added cis-10-heptadecenoic acid (17:1Δ10) was converted into cis-6,10-heptadecadienoic (17:2Δ6,10). These data demonstrate the ability of Δ6-FAD to introduce the first double bond into the unsaturated substrates and suggests that it "counts" from the carboxyl end, irrespective of the absence or presence of a previous double bond in an FA chain.

Enantiomeric separation of triacylglycerols containing fatty acids with a ring (cyclofatty acids)

Triacylglycerols (TAGs) containing cyclofatty acids (cycloFAs) from two oilseeds of Sterculia foetida and Hydnocarpus wightiana were analysed using both reversed-phase (RP18) and chiral phase columns. TAGs were identified using high-resolution electrospray ionization mass spectrometry in the positive ion mode. Fifty-five molecular species of TAGs have been identified in sterculic oil, 27 of which contained at least one cyclopropenyl-FA (e.g., malvalic or sterculic acids). The structures of regioisomers and enantiomers were determined for five major TAGs with cyclopropenyl-FAs.One hundred thirty-six TAGs were identified in chaulmoogra oil, 71 of which contained at least one cyclopentenyl-FA (e.g., gorlic, chaulmoogric, and hydnocarpic acids, etc.). Furthermore, in three molecular species, regioisomers and enantiomers were identified using HPLC on a chiral phase column. Eight molecular species of TAGs were prepared through organic synthesis to facilitate the identification of enantiomers. Retention times of fatty acid-containing triacylglycerols with one ring and one double bond are very similar to triacylglycerols with a dienoic fatty acid, but elution times are shorter. For example, dimalvaloylpalmitate elutes earlier than dilinoleylpalmitate.The order of elution of TAGs on the chiral column differs. In TAGs with 2 degrees of unsaturation (ring and double bond, e.g. PStP-StPP-PPSt), the order of elution is symmetric-asymmetric-asymmetric TAGs. TAGs with 4 degrees of unsaturation (one ring and three double bonds or two rings and two double bonds) present a different pattern. When TAGs contain two rings and two double bonds, the order of elution TAGs is asymmetric-symmetric-asymmetric (StStP-StPSt-PStSt); when TAGs contain a ring and 3 double bonds, the elution order is symmetric-asymmetric-asymmetric TAGs (OStO-StOO-OOSt). In species with a higher degree of unsaturation (e.g., 5), the elution order of the TAGs is asymmetric-asymmetric-symmetric (e.g. CCO-OCC-COC).

Evaluation of Antioxidant Efficiency of Croton tiglium L. Seeds Extracts after Incorporating Silver Nanoparticles

This study aimed to enhance efficiency of the different Croton tiglium (C. tiglium) seeds extracts by incorporation of silver nanoparticles (Ag-NPs) through raised up cytotoxicity against growth of human colon cancer cells. C. tiglium seeds contain various phytoconstituents e.g., carbohydrates (glycosides), flavonoids, sterols (triterpenes), alkaloids and proteins. The protein was hydrolyzed in the dried aqueous seeds extract into free amino acids, the essential amino acids (20.71%) & nonessential amino acids (79.29%). Furthermore, the mucilage in the dried aqueous seeds extract and the total identified sugars represent ~81.21 % of the total mucilage hydrolyzate. The lipoidal contents in the saponifiable matter of the petroleum ether extract, the total saturated fatty acids (13.68%), total monoenoic fatty acids (34.49%), total dienoic fatty acids (45.76%) and total identified fatty acids (93.93%). The unsaponifiable matter was represented by saturated hydrocarbons (40.73%), unsaturated hydrocarbons (18.93%), fatty alcohols (10.08%), sterols (10.61%) and total identified compounds (80.35%). In addition, there were four compounds (β sitosterol, α-amyrin, Oleanolic acid and 3-O-β-D-glucopyranosyl-β-sitosterol (daucosterol)) isolated from the petroleum ether extract. Additionally, incorporation of Ag-NPs into the extract caused no toxicity on the experimental animals when administrated orally. It was found that the median lethal dose (LD50) of the ethanolic, petroleum ether and aqueous seeds extract-Ag nanocomposites was about 7.95, 5.2 and 65 ml/Kg, respectively.

Diverse Odd-Chain Monoenoic Fatty Acids and Novel Non-Methylene-Interrupted Heptadecadienoic Acids in Ovaries of the Limpet Cellana toreuma.

Highly diverse dienoic fatty acids (FA), especially non-methylene-interrupted (NMI) FA, have been recognized in triacylglycerols (TAG) and polar lipids of ovaries of the limpet Cellana toreuma. To gain additional insights into the structural diversity of FA in ovaries, this study aimed to clarify previously undescribed minor monoenoic FA isomers and unidentified minor NMI FA by combined argentation thin-layer chromatography (TLC) and gas chromatography-mass spectrometry (GC-MS) of their 3-pyridylcarbinol derivatives. A total 66 monoenoic FA from C14 to C22, including 12 branched-chain FA, were identified. A surprising finding was a series of 13 heptadecenoic acids with double bonds at either Δ5, Δ6, Δ7, Δ8, Δ9, Δ10, Δ11, Δ12, Δ13, Δ15, or Δ16 positions. Besides previously identified NMI FA, 7,18-nonadecadienoic (19:2Δ7,18), 9,18-nonadecadienoic (19:2Δ9,18), 11,18-nonadecadienoic (19:2Δ11,18), 7,20-heneicosadienoic (21:2Δ7,20), and 11,20-heneicosadienoic (21:2Δ11,20) acids, two novel related NMI FA, 5,16-heptadecadienoic (17:2Δ5,16) and 7,16-heptadecadienoic (17:2Δ7,16) acids, were found in TAG. These findings could provide new insights into clarifying the biological characteristics of marine NMI FA.

Membrane Lipid Composition upon Normal and Patterned Wood Formation in Betula Pendula Roth

A comparative study of two forms of Betula pendula Roth differing in wood structure (B. pendula var. pendula with common straight-grained wood and B. pendula var. carelica with abnormal patterned wood) has demonstrated that the level of phospholipids reflects the content of parenchyma cells in the wood and can be regarded as an indicator of the abnormality degree in the tissue structure. The content of glycolipids testifies to the dynamics of the plastid apparatus condition and correlates with the activity of the storage function in the wood parenchyma cells. It is shown that two directions in the differentiation of cambial derivatives, namely by the pathway of cell death (vessels and fibrous elements) and the preservation of a live protoplast (parenchyma cells), correlate with different fatty acid compositions of membrane lipids. In the first case, the share of saturated fatty acids in the composition of phospholipids and glycolipids increases, indicating a deterioration of the functional characteristics of cell membranes. In the latter case, the share of unsaturated, mainly dienoic fatty acids, increases, which reflects a rise in the activity of cell membranes. During periods with the highest rate of metabolism, the content of polyunsaturated, mainly trienoic fatty acids increase in membrane lipids.

The FAD2 Gene in Plants: Occurrence, Regulation, and Role.

Vegetable oils rich in oleic acid are more desirable than oils rich in polyunsaturated and saturated fatty acids. The biological switch of oleic acid to linoleic acid is facilitated by fatty acid desaturase 2 enzyme that is further classified into FAD2-1, FAD2-2, FAD2-3, and FAD2-4. The genes coding these enzymes have high sequence similarity, but differ mostly in their expression patterns. The seed-type FAD2 genes had evolved independently after segregation by duplication from constitutively expressed FAD2 genes. Temperature, light and wounding effectively regulate FAD2 expression in plants. FAD2 genes are expressed differently in different tissues of the plant, and the over-expression of FAD2 modifies physiological and vegetative characteristics. The activity of FAD2 leads to an increase in the content of dienoic fatty acids, and hence increases the resistance toward cold and salt stress. The thorough study of the FAD2 gene is important for understanding the expression, regulation and mechanism that will help in improving the quality of oil and stress resistance in plants.

Effect of dietary flax seed and oil on milk yield, gross composition, and fatty acid profile in dairy cows: A meta-analysis and meta-regression

Several experiments were conducted over the past few years to evaluate the feeding value of flax seed and oil in dairy cow diets. The current meta-analysis and meta-regression was undertaken to assess the overall effect of different forms of flax, as a source of trienoic (cis-9,cis-12,cis-15 18:3) fatty acids (FA), on lactation performance and on transfer efficiency of its constituent n-3 FA from diet to milk fat. Comparisons were first conducted with nonsupplemented controls or with diets containing either saturated (mainly 16:0 or 18:0 or both), monoenoic (mainly cis-9 18:1), or dienoic (mainly cis-9,cis-12 18:2) FA. Results indicate that supplementing flax seed and oil decreased dry matter intake, as well as actual and energy-corrected milk yield without affecting the efficiency of utilization of dietary dry matter or energy as compared with nonsupplemented iso-energetic controls. When compared with the other 3 types of dietary fat evaluated, flax rich in trienoic FA supported a yield of energy-corrected milk similar to supplements rich in saturated, monoenoic, or dienoic FA. Greater milk fat concentration and feed efficiency were observed with saturated supplements. However, milk fat concentration and yield were lower with dienoic FA than with flax supplements. Further analyses were conducted to compare the effect of different forms of flax oil, seed, or fractions of seed. Among the 6 categories evaluated, mechanically processed whole seed (rolled or ground) allowed the greatest yield of energy-corrected milk and the best feed efficiency when compared with free oil, intact or extruded whole seed, protected flax, and flax hulls. Feeding protected flax and flax hulls allowed the greatest milk fat concentration of cis-9,cis-12,cis-15 18:3. Moreover, the greatest transfer efficiencies of this fatty acid from diet to milk were recorded with the same 2 treatments, plus the mechanically processed whole seed. These results make this last category the most suitable treatment, among the 6 flax forms evaluated, to combine optimum lactation performance and protection of flax constituent cis-9,cis-12,cis-15 18:3.

Anti‐mutagenic Properties of Mono‐ and Dienoic Acid Biohydrogenation Products from Beef Fat

Unsaturated fatty acid biohydrogenation products from beef fat and pure fatty acids were subjected to the Ames Salmonella mutagenicity testing, including monounsaturated fatty acids [MUFA: oleic acid, vaccenic acid, elaidic acid; beef fatty acid fractions rich in trans (t)11/t13-t14-18:1 (t11,13,14-Frac), t10-18:1 (t10-Frac)] and dienoic fatty acids [linoleic acid, conjugated linoleic isomers cis (c)9,t11-18:2 and t10,c12-18:2, and a mixed beef dienoic fatty acid fraction high in c9,t13-/t8,c12/t11c15-18:2 (MD)]. Significantly higher anti-mutagenic effects of oleic acid, vaccenic acid, t11, 13, 14-Frac, and t10-Frac against daunomycin were observed at 2.5mg. All dienoic acids except MD significantly reduced daunomycin mutagenicity at ≥0.25mg. Anti-mutagenicity of oleic and vaccenic acids against 2-aminoanthracene was found at 2.5 and 0.25mg, respectively. All dienoic acids significantly reduced 2-aminoanthracene mutagenicity at ≥0.25mg. Findings of this study show that unsaturated fatty acids, including trans-fatty acids commonly found in beef, can act as strong anti-mutagens.

Effect of cadmium exposure on essential omega-3 fatty acids in the edible bivalve Donax trunculus.

Donax trunculus is the most consumed bivalve by the local population of the Northeast Algeria for its nutritional value. Therefore, the aim of the current study was to determine the effects of cadmium (Cd), a known toxic metal, on the alterations in main essential omega-3 fatty acids, i.e., eicosapentaenoic acid (EPA; C20:5n-3) and docosahexaenoic acid (DHA; C22:6n-3), in male and female gonads of D. trunculus during the reproduction period at spring (before spawning). Additionally, this work seeks to describe the relation between EPA and DHA with non-methylene-interrupted dienoic (NMID) fatty acids, and explores their possible contribution of to protect against Cd stress. The samples were collected at El Battah, a relatively clean sea shore, and reared in the laboratory. Physico-chemical parameters such as temperature, pH, salinity, and dissolved oxygen were measured. Cd was added to the rearing water at two sublethal concentrations (LC10 and LC25-96h, as determined previously). A two-way ANOVA analysis indicated significant effects of concentrations and genders for both fatty acids. Our results showed a significant reduction in EPA and DHA concentrations in the both genders, with a strong effect in females. There was also a negative correlation between NMID fatty acids and the two essential omega-3 fatty acids for each gender.

Differentiation between Yeast Species, and Strains within a Species, by Cellular Fatty Acid Analysis. 2. Saccharomyces cerevisiae

Fatty acid extracts of 50 Saccharomyces cerevisiae strains, grown under rigidly standardised conditions, were subjected to capillary gas chromatographic analysis on a polar column. Strains contained saturated, mono-unsaturated and trace amounts of dienoic fatty acids. The mean relative percentages of 10 fatty acids were used to differentiate between the strains studied. Forty-six strains could be differentiated from all others in the group, based on the criterion that when comparing two strains the CFAP's were considered unique if the MRP's of at least one fatty acid differed at the 1 % level. Holman's Index of Relationship proved to be a useful tool for indicating degree of similarity between fatty acid proftles. Efforts to distinguish between the species Sacch. cerevisiae and Sacch. bayanus were not successful. More analyses on authentic strains (determined by DNA homology) are necessary to confirm whether such a separation is possible or not. Oenologically important changes that occurred in a commercial dried yeast during production were reflected in the fatty acid proftles of the dried products. Index of Relationship between the fatty acid profiles of five other dried yeast products, and the mother cultures from which they were produced, was very high indicating no change during the commercial production phase. Changes, or lack of change, were confirmed by fermentation studies.

Novel Odd-Chain Fatty Acids with a Terminal Double Bond in Ovaries of the Limpet Cellana toreuma.

Our previous study characterized highly diverse dienoic fatty acids (FA), in particular an uncommon non-methylene-interrupted (NMI) FA, in the ovaries of the Japanese limpet Cellana toreuma belonging to the archaeogastropods, but many minor chemically unidentified FA remain. In this study, among previously unidentified FA (less than 0.1% of total FA), four novel NMI FA with a terminal double bond [7,18-nonadecadienoic (19:2Δ7,18), 11,18-nonadecadienoic (19:2Δ11,18), 7,20-heneicosadienoic (21:2Δ7,20), and 11,20-heneicosadienoic (21:2Δ11,20) acids] were found, along with known 14-pentadecenoic (15:1Δ14), 16-heptadecenoic (17:1Δ16), and 9,18-nonadecadienoic (19:2Δ9,18) acids, based on capillary GC-MS of their methyl esters, 3-pyridylcarbinol derivatives, and argentation thin-layer chromatography. From our findings, possible biosynthetic pathways for the novel FA are discussed.

An alternative analytical method based on ultrasound micro bath hydrolysis and GC-MS analysis for the characterization of organic biomarkers in archaeological ceramics.

The analysis of organic biomarkers in ancient and valuable archaeological remains provides a worthwhile source of information regarding their management. This work was focused on the development of an analytical procedure to characterize organic residues that have remained in archaeological ceramic samples. A novel analytical approach based on an alkaline hydrolysis by means of an ultrasound micro bath followed by liquid extraction was proposed to isolate saturated and unsaturated fatty acids, degradation products such as dihydroxy acids or dienoic fatty acids, isoprenoid fatty acids, and many other biomarkers from archaeological remains. This main goal has been achieved after the optimization of the main parameters affecting the hydrolysis step, the extraction procedure, and the derivatization step prior to the gas chromatography-mass spectrometry analysis. In this work, archaeological ceramic remains suspected to have been used by Basque Whalers to store whale oil in the period from the sixteenth to the seventeenth century were studied. Nevertheless, the proposed method is useful to determine the organic remains preserved in many other archaeological ceramic remains. Moreover, this methodology can be used to determine organic remains in any porous ceramic, archaeological or not. The preliminary results of the analysis of ceramic vessels led to the determination of some interesting unsaturated compounds such as 11-eicosenoic acid, an important biomarker of marine commodities, and several saturated fatty acids, which could be indicative of having used the vessels to store whale oil. Graphical abstract ᅟ.

Flexible Approach to (5Z,9Z)‐Dienoic Fatty Acids Relevant to the Synthesis of Demospongic Acids and Related Natural Products

A flexible and efficient synthesis of the potent human topoisomerase inhibitor (5Z,9Z)‐eicosa‐5,9‐dienoic acid was explored; the presented method represents a generally applicable approach towards demospongic acids and related natural products. Key steps of the synthesis involve chemoselective hydroboration, Corey–Fuchs alkynylation, Z‐selective Lindlar reduction, tetrapropylammonium perruthenate catalyzed direct oxidation of a primary alcohol to the corresponding acid, and Arndt–Eistert homologation. Thus, the total synthesis of (5Z,9Z)‐eicosa‐5,9‐dienoic acid was achieved in 10 steps in an overall yield of 20 %.

The role of defensin fragment in the regulation of fatty acid composition of membrane phospholipids in epithelial-like cells

It is shown that a tetrapeptide fragment of defensin does not alter the phospholipid composition in the membranes of CHO-K1 cells but regulates the fatty acid composition of phosphatidylcholine, phosphatidylethanolamine (PEA), phosphatidylserine (PS), and phosphatidylinositol (PI). Incubation of the cells in the presence of this tetrapeptide resulted in modification of unsaturated fatty acid composition in the studied phospholipids. The content of monoenoic (mainly C18 : 1ω9) and/or dienoic (C18 : 2ω6) fatty acids increased, while the level of polyenoic fatty acids decreased. It was found that in the polyenoic fatty acid group of the PEA, PS and PI molecules, the ω3-/ω6-acid ratio decreased mainly due to the lower content of long-chain ω3-acids with 20 and/or 22 carbonic atoms. The possible role of this peptide in inhibition of the activity of Δ6- and Δ5-desaturases involved in the synthesis of long-chain polyenoic fatty acids, the quantitative alteration of which in phospholipids influences physicochemical parameters in cell membranes, is discussed.

An Unprecedented Occurrence of Δ5,9- and Δ9,15-Dienoic Fatty Acids in Ovaries of the Archaeogastropod Limpet Cellana toreuma.

A detailed structural diversity of dienoic fatty acids (FA), including non-methylene-interrupted dienoic FA, of triacylglycerols and polar lipids in ovaries of Cellana toreuma was clarified for the first time by using capillary gas chromatography-mass spectrometry of their 3-pyridylcarbinol esters and argentation thin-layer chromatography. Interestingly, in addition to 5,9-octadecadienoic (18:2Δ5,9), 5,9-eicosadienoic (20:2Δ5,9), 5,9-heneicosadienoic (21:2Δ5,9), 5,9-docosadienoic (22:2Δ5,9), 5,9-tricosadienoic (23:2Δ5,9), and 5,9-tetracosadienoic (24:2Δ5,9) acids, previously identified in ovaries of C. grata, rare FA 5,9-hexadecadienoic (16:2Δ5,9), 5,9-nonadecadienoic (19:2Δ5,9), and 21-methyl-5,9-docosadienoic (iso 23:2Δ5,9) were newly recognized in ovaries of C. toreuma. Detectable amounts of four Δ9,15-dienoic FA were present in the ovary lipids. The FA identified were one novel 9,15-heneicosadienoic (21:2Δ9,15) acid and known 9,15-docosadienoic (22:2Δ9,15), 9,15-tricosadienoic (23:2Δ9,15), and 9,15-tetracosadienoic (24:2Δ9,15) acids. The findings help to explain the broad evidence of the structural diversity in marine gastropods and suggest biomarkers to evaluate marine food web relations.

Threonine 286 of fatty acid desaturase 7 is essential for ω-3 fatty acid desaturation in the green microalga Chlamydomonas reinhardtii.

Omega-3 fatty acid desaturases catalyze the conversion of dienoic fatty acids (C18:2 and C16:2) into trienoic fatty acids (C18:3 and C16:3), accounting for more than 50% of the total fatty acids in higher plants and the green microalga Chlamydomonas reinhardtii. Here, we describe a Thr residue located in the fourth transmembrane domain of fatty acid desaturase 7 (FAD7) that is essential for the biosynthesis of ω-3 fatty acids in C. reinhardtii. The ω-3 fatty acid deficiency in strain CC-620, which contains a putative missense mutation at Thr286 of CrFAD7, was recovered by the overexpression of CC-125 CrFAD7. A Ser substitution in position 286 was able to partially complement the phenotype of the ω-3 fatty acid deficiency, but other substitution variants, such as Tyr, His, Cys, and Gly, failed to do so. Prediction of the phosphorylation target site revealed that Thr286 may be phosphorylated. Analysis of the structural conformation of CC-620 CrFAD7 via topology prediction (and bends in the helix) shows that this missense mutation may collapse the catalytic structure of CrFAD7. Taken together, this study suggests that Thr286 is essential for the maintaining the catalytic structure of CrFAD7.

Long-chain PUFA enrichment in microalgae and metabolic dynamics inTapes philippinarumlarvae

The possibility of increasing n-3 and n-6 long-chain polyunsaturated fatty acids (PUFA) content in microalgal mixtures used to feed Tapes philippinarum larvae was explored by lowering culture temperature from 26 to 14 °C. Although fatty acid composition of different microalgal species has a genetic basis, the algal cultures grown at 14 °C significantly increased the content of long-chain n-3 PUFA in Isocrysis galbana and in Thalassiosira pseudonana, while in Tetraselmis tetrathelo, the PUFA increase only involved shorter chain PUFA, namely 16:4n-3 and 18:4n-3. However, larvae fed on the PUFA enriched microalgal mixture did not show improvements in growth and survival performances with respect to the control group fed the microalgal mixture grown at 26 °C. From a biochemical perspective, two key aspects emerged from the results: (i) clam larvae have adequate biotransformation and selection skills to adjust fatty acid profile to their requirements as they can even modulate the incorporation of essential long-chain PUFA as 20:5n-3 and 22:6n-3 when the dietary supply exceeds the physiological requirements; (ii) bivalve can biosynthesize non-methylene-interrupted dienoic (NMID) fatty acids as confirmed by the constancy of relative proportion with larvae growth in spite of the NMID fatty acid absence in the diet.

Effects of microalgal diet on growth, survival, biochemical and fatty acid composition of Ruditapes decussatus larvae

Successful bivalve larval growth and survival depend on stored reserves provided by diet. The aim of this study was to evaluate the effects of microalgal diet on growth, survival, together with biochemical and fatty acid composition during larval development in grooved carpet shell (Ruditapes decussatus). Four mono- and multi-species diets were tested: (1) Isochrysis galbana, Pavlova lutheri and Chaetoceros muelleri (1:1:1, IPC); (2) I. galbana, P. lutheri and C. muelleri (1:1:2, IP2C); (3) I. galbana and P. lutheri (1:1, IP); (4) C. muelleri (C). Our results showed that feeding regime greatly influenced larval growth and survival, as well as biochemical and fatty acid composition. Higher growth and survival rates were observed in the IPC, IP2C and C diets, which all include C. muelleri. Despite the fact that the larvae fed with IP exhibited the lowest length at settlement and survival, they stored more total lipids than any of the diets including C. muelleri. The IP and IPC diets exhibited a higher percentage of total lipids, whereas IP2C and C showed a higher proportion of proteins. Lipid and carbohydrate concentrations in these diets negatively affected growth and growth and survival of the larvae, respectively. Protein content of the larvae was however positively related to larval survival, whereas lipid content of the larvae negatively affected growth. Fatty acid (FA) profile of neutral lipids (NL) and polar lipids (PL) of 22-day-old larvae clearly reflected the FA proportion of each diet. Dietary DHA and DHA in NL of the larvae were negatively related to larvae growth. DHA incorporation into PL in larvae fed with DHA-deficient diets was compensated by an enrichment in EPA, 18:0dma, 22:5(n-3) and 22:2 non-methylene-interrupted dienoic FA. According to these results, the presence of C. muelleri in the diet seems to promote better growth and survival of R. decussatus larvae.