Artículos de revistas: "Fatty acid elongation"

1

Zank, T. K., U. Zähringer, J. Lerchl y E. Heinz. "Cloning and functional expression of the first plant fatty acid elongase specific for Δ6-polyunsaturated fatty acids". Biochemical Society Transactions 28, n.º 6 (1 de diciembre de 2000): 654–58. http://dx.doi.org/10.1042/bst0280654.

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In order to elucidate the biosynthesis of longchain polyunsaturated fatty acids (PUFAs) in plants we searched for a cDNA encoding a Δ6-specific PUFA elongase from Physcomitrella patens which is known to contain high proportions of arachidonic acid (20:4 Δ5,8,11,14). 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 C18 Δ6-polyunsaturated fatty acids γ-linolenic acid (18:3 Δ6,9,12) and stearidonic acid (18:4 Δ6,9,12,15), which were recovered to 45–51% as their elongation products. In contrast, linoleic and α-linolenic acids were hardly elongated and we could not measure any elongation of saturated and mono-unsaturated fatty acids (including 18:1 Δ6), indicating that the elongase is highly specific for the polyunsaturated nature of the fatty acid acting as substrate.

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2

Das, T., J. M. Thurmond, E. Bobik, A. E. Leonard, J. M. Parker-Barnes, Y. S. Huang y P. Mukerji. "Polyunsaturated fatty acid-specific elongation enzymes". Biochemical Society Transactions 28, n.º 6 (1 de diciembre de 2000): 658–60. http://dx.doi.org/10.1042/bst0280658.

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We have isolated a novel gene (GLELO) from Mortierella alpina and its homologue (CEELO1) from Caenorhabditis elegans and demonstrate the involvement of their encoded proteins in the elongation of C18 polyunsaturated fatty acids.

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3

Torella, J. P., T. J. Ford, S. N. Kim, A. M. Chen, J. C. Way y P. A. Silver. "Tailored fatty acid synthesis via dynamic control of fatty acid elongation". Proceedings of the National Academy of Sciences 110, n.º 28 (24 de junio de 2013): 11290–95. http://dx.doi.org/10.1073/pnas.1307129110.

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4

Christiansen, E. N., T. Rørtveit, K. R. Norum y M. S. Thomassen. "Fatty-acid chain elongation in rat small intestine". Biochemical Journal 237, n.º 1 (1 de julio de 1986): 293–95. http://dx.doi.org/10.1042/bj2370293.

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Microsomal fractions from rat small intestine contain a fatty-acid chain-elongation activity. Cofactor requirements are similar to those of the liver microsomal system, but substrate specificity is different. The polyunsaturated arachidonic and timnodonic acids were elongated at very low rates. These results suggest that the relative contents of specific chain-elongation enzymes are different in liver and small intestine.

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5

Dyer, William E. "Inhibitors of Fatty Acid Synthesis and Elongation". Journal of Natural Resources and Life Sciences Education 37, n.º 1 (2008): 132. http://dx.doi.org/10.2134/jnrlse2008.371132x.

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6

Tehlivets, Oksana, Kim Scheuringer y Sepp D. Kohlwein. "Fatty acid synthesis and elongation in yeast". Biochimica et Biophysica Acta (BBA) - Molecular and Cell Biology of Lipids 1771, n.º 3 (marzo de 2007): 255–70. http://dx.doi.org/10.1016/j.bbalip.2006.07.004.

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7

Matthes, Bernd, Jochen Schmalfuß y Peter Böger. "Chloroacetamide Mode of Action, II: Inhibition of Very Long Chain Fatty Acid Synthesis in Higher Plants". Zeitschrift für Naturforschung C 53, n.º 11-12 (1 de diciembre de 1998): 1004–11. http://dx.doi.org/10.1515/znc-1998-11-1211.

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Abstract In short-term -experiments [14C]-labelled malonic acid, stearic acid and acetate have been incorporated into leaf fatty acids of seedlings of Cucumis sativus, Hordeum vulgare and Zea mays. The pattern of labelled fatty acids changed markedly by treatment with the chloroacetamide herbicides metazachlor, metolachlor or butachlor. During a 2-h incubation time, 1 μᴍ chloroacetamide specifically inhibited up to 100% the formation of the saturated very long chain fatty acids (V LCFAs) with a carbon number of 20, 22 and 24. In cucumber and barley a 50% inhibition of VLCFA formation is achieved with 10 to 100 nM metazachlor representing the most sensitive effect of inhibitors on fatty acid elongation reported as yet. Sensitivity of fatty acid elongation depends on the amide structure present in the com pound and on its stereochemistry. Inhibition of oleic acid incorporation correlates with growth inhibition by chloroacetam ides of the intact cell (comp. Pestic. Sei. 52, 381-387, 1998). The present study extends this correlation to inhibition of VLCFA synthesis in higher plants. Obviously the primary mode of action of chloroacetam ides and related herbicidal substances is involved in the enzymic four-step fatty acid elongation system.

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8

Abulnaja, Khalid O. y John L. Harwood. "Effect of a Safener Towards Thiocarbamates on Plant Lipid Metabolism". Zeitschrift für Naturforschung C 46, n.º 9-10 (1 de octubre de 1991): 931–33. http://dx.doi.org/10.1515/znc-1991-9-1035.

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Abstract It has been found that various thiocarbamate herbicides, known to alter surface wax and cutin synthesis, inhibit the elongation of fatty acids. We have proposed this as a mode of action of such compounds. Because it is believed that the sulphoxide metabolites of thiocarbamates are the active intermediates, we have examined the action of 1-aminobenzotriazole (an inhibitor of sulphoxide formation) on the inhibition of very long-chain fatty acid biosynthesis. In all tissues tested, aminobenzotriazole was able to block the specific inhibitory effect of thiocarbamates on fatty acid elongation. These results add further support to our proposal that fatty acid elongation is a sensitive target site for thiocarbamate herbicides in plants.

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9

Kohlwein, Sepp D., Sandra Eder, Chan-Seok Oh, Charles E. Martin, Ken Gable, Dagmar Bacikova y Teresa Dunn. "Tsc13p Is Required for Fatty Acid Elongation and Localizes to a Novel Structure at the Nuclear-Vacuolar Interface inSaccharomyces cerevisiae". Molecular and Cellular Biology 21, n.º 1 (1 de enero de 2001): 109–25. http://dx.doi.org/10.1128/mcb.21.1.109-125.2001.

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ABSTRACT The TSC13/YDL015c gene was identified in a screen for suppressors of the calcium sensitivity of csg2Δ mutants that are defective in sphingolipid synthesis. The fatty acid moiety of sphingolipids in Saccharomyces cerevisiae is a very long chain fatty acid (VLCFA) that is synthesized by a microsomal enzyme system that lengthens the palmitate produced by cytosolic fatty acid synthase by two carbon units in each cycle of elongation. TheTSC13 gene encodes a protein required for elongation, possibly the enoyl reductase that catalyzes the last step in each cycle of elongation. The tsc13 mutant accumulates high levels of long-chain bases as well as ceramides that harbor fatty acids with chain lengths shorter than 26 carbons. These phenotypes are exacerbated by the deletion of either the ELO2 or ELO3gene, both of which have previously been shown to be required for VLCFA synthesis. Compromising the synthesis of malonyl coenzyme A (malonyl-CoA) by inactivating acetyl-CoA carboxylase in atsc13 mutant is lethal, further supporting a role of Tsc13p in VLCFA synthesis. Tsc13p coimmunoprecipitates with Elo2p and Elo3p, suggesting that the elongating proteins are organized in a complex. Tsc13p localizes to the endoplasmic reticulum and is highly enriched in a novel structure marking nuclear-vacuolar junctions.

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10

Schneiter, Roger, Verena Tatzer, Gabriela Gogg, Erich Leitner y Sepp Dieter Kohlwein. "Elo1p-Dependent Carboxy-Terminal Elongation of C14:1Δ9 to C16:1Δ11 Fatty Acids inSaccharomyces cerevisiae". Journal of Bacteriology 182, n.º 13 (1 de julio de 2000): 3655–60. http://dx.doi.org/10.1128/jb.182.13.3655-3660.2000.

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ABSTRACT Saccharomyces cerevisiae medium-chain acyl elongase (ELO1) mutants have previously been isolated in screens for fatty acid synthetase (FAS) mutants that fail to grow on myristic acid (C14:0)-supplemented media. Here we report that wild-type cells cultivated in myristoleic acid (C14:1Δ9)-supplemented media synthesized a novel unsaturated fatty acid that was identified as C16:1Δ11 fatty acid by gas chromatography-mass spectroscopy. Synthesis of C16:1Δ11 was dependent on a functional ELO1 gene, indicating that Elo1p catalyzes carboxy-terminal elongation of unsaturated fatty acids (α-elongation). In wild-type cells, the C16:1Δ11elongation product accounted for approximately 12% of the total fatty acids. This increased to 18% in cells that lacked a functional acyl chain desaturase (ole1Δ mutants) and hence were fully dependent on uptake and elongation of C14:1. The observation thatole1Δ mutant cells grew almost like wild type on medium supplemented with C14:1 indicated that uptake and elongation of unsaturated fatty acids were efficient. Interestingly, wild-type cells supplemented with either C14:1 or C16:1 fatty acids displayed dramatic alterations in their phospholipid composition, suggesting that the availability of acyl chains is a dominant determinant of the phospholipid class composition of cellular membranes. In particular, the relative content of the two major phospholipid classes, phosphatidylethanolamine and phosphatidylcholine, was strongly dependent on the chain length of the supplemented fatty acid. Moreover, analysis of the acyl chain composition of individual phospholipid classes in cells supplemented with C14:1 revealed that the relative degree of acyl chain saturation characteristic for each phospholipid class appeared to be conserved, despite the gross alteration in the cellular acyl chain pool. Comparison of the distribution of fatty acids that were taken up and elongated (C16:1Δ11) to those that were endogenously synthesized by fatty acid synthetase and then desaturated by Ole1p (C16:1Δ9) in individual phospholipid classes finally suggested the presence of two different pools of diacylglycerol species. These results will be discussed in terms of biosynthesis of different phospholipid classes via either the de novo or the Kennedy pathway.

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11

Gong, Yi y Xiaoling Miao. "Short Chain Fatty Acid Biosynthesis in Microalgae Synechococcus sp. PCC 7942". Marine Drugs 17, n.º 5 (28 de abril de 2019): 255. http://dx.doi.org/10.3390/md17050255.

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Short chain fatty acids (SCFAs) are valued as a functional material in cosmetics. Cyanobacteria can accumulate SCFAs under some conditions, the related mechanism is unclear. Two potential genes Synpcc7942_0537 (fabB/F) and Synpcc7942_1455 (fabH) in Synechococcus sp. PCC 7942 have homology with fabB/F and fabH encoding β-ketoacyl ACP synthases (I/II/III) in plants. Therefore, effects of culture time and cerulenin on SCFAs accumulation, expression levels and functions of these two potential genes were studied. The results showed Synechococcus sp. PCC 7942 accumulated high SCFAs (C12 + C14) in early growth stage (day 4) and at 7.5g/L cerulenin concentration, reaching to 2.44% and 2.84% of the total fatty acids respectively, where fabB/F expression was down-regulated. Fatty acid composition analysis showed C14 increased by 65.19% and 130% respectively, when fabB/F and fabH were antisense expressed. C14 increased by 10.79% (fab(B/F)−) and 6.47% (fabH−) under mutation conditions, while C8 increased by six times in fab(B/F)− mutant strain. These results suggested fabB/F is involved in fatty acid elongation (C <18) and the elongation of cis-16:1 to cis-18:1 fatty acid in Synechococcus sp. PCC 7942, while fabH was involved in elongation of fatty acid synthesis, which were further confirmed in complementary experiments of E. coli. The research could provide the scientific basis for the breeding of SCFA-rich microalgae species.

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12

Tvrdik, Petr, Rolf Westerberg, Sandra Silve, Abolfazl Asadi, Andreas Jakobsson, Barbara Cannon, Gerard Loison y Anders Jacobsson. "Role of a New Mammalian Gene Family in the Biosynthesis of Very Long Chain Fatty Acids and Sphingolipids". Journal of Cell Biology 149, n.º 3 (1 de mayo de 2000): 707–18. http://dx.doi.org/10.1083/jcb.149.3.707.

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Whereas the physiological significance of microsomal fatty acid elongation is generally appreciated, its molecular nature is poorly understood. Here, we describe tissue-specific regulation of a novel mouse gene family encoding components implicated in the synthesis of very long chain fatty acids. The Ssc1 gene appears to be ubiquitously expressed, whereas Ssc2 and Cig30 show a restricted expression pattern. Their translation products are all integral membrane proteins with five putative transmembrane domains. By complementing the homologous yeast mutants, we found that Ssc1 could rescue normal sphingolipid synthesis in the sur4/elo3 mutant lacking the ability to synthesize cerotic acid (C26:0). Similarly, Cig30 reverted the phenotype of the fen1/elo2 mutant that has reduced levels of fatty acids in the C20–C24 range. Further, we show that Ssc1 mRNA levels were markedly decreased in the brains of myelin-deficient mouse mutants known to have very low fatty acid chain elongation activity. Conversely, the dramatic induction of Cig30 expression during brown fat recruitment coincided with elevated elongation activity. Our results strongly implicate this new mammalian gene family in tissue-specific synthesis of very long chain fatty acids and sphingolipids.

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13

Morais, Sofia, Miguel Torres, Francisco Hontoria, Óscar Monroig, Inma Varó, María José Agulleiro y Juan Carlos Navarro. "Molecular and Functional Characterization of Elovl4 Genes in Sparus aurata and Solea senegalensis Pointing to a Critical Role in Very Long-Chain (>C24) Fatty Acid Synthesis during Early Neural Development of Fish". International Journal of Molecular Sciences 21, n.º 10 (15 de mayo de 2020): 3514. http://dx.doi.org/10.3390/ijms21103514.

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Very long-chain fatty acids (VLC-FA) play critical roles in neural tissues during the early development of vertebrates. However, studies on VLC-FA in fish are scarce. The biosynthesis of VLC-FA is mediated by elongation of very long-chain fatty acid 4 (Elovl4) proteins and, consequently, the complement and activity of these enzymes determines the capacity that a given species has for satisfying its physiological demands, in particular for the correct development of neurophysiological functions. The present study aimed to characterize and localize the expression of elovl4 genes from Sparus aurata and Solea senegalensis, as well as to determine the function of their encoded proteins. The results confirmed that both fish possess two distinct elovl4 genes, named elovl4a and elovl4b. Functional assays demonstrated that both Elovl4 isoforms had the capability to elongate long-chain (C20–24), both saturated (SFA) and polyunsaturated (PUFA), fatty acid precursors to VLC-FA. In spite of their overlapping activity, Elovl4a was more active in VLC-SFA elongation, while Elovl4b had a preponderant elongation activity towards n-3 PUFA substrates, particularly in S. aurata, being additionally the only isoform that is capable of elongating docosahexaenoic acid (DHA). A preferential expression of elovl4 genes was measured in neural tissues, being elovl4a and elovl4b mRNAs mostly found in brain and eyes, respectively.

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14

Robinson, B. S., D. W. Johnson y A. Poulos. "Metabolism of hexacosatetraenoic acid (C26:4,n-6) in immature rat brain". Biochemical Journal 267, n.º 2 (15 de abril de 1990): 561–64. http://dx.doi.org/10.1042/bj2670561.

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Rat brain was recently found to contain polyenoic very-long-chain fatty acids (VLCFA) belonging to the n-3 and n-6 series with four, five and six double bonds and even-carbon chain lengths from 24 to 38 [Robinson, Johnson & Poulos (1990) Biochem. J. 265, 763-767]. In the present paper, the metabolism in vivo of hexacosatetraenoic acid (C26:4,n-6) was studied in neonatal rat brain. Rats were injected intracerebrally with [1-14C]C26:4,n-6 and the labelled metabolites were examined after 4 h. Radioactivity was detected mainly in non-esterified fatty acids, with smaller amounts in other neutral lipids and phospholipids. Radiolabelled fatty acid products included C28-36 tetraenoic and C26-28 pentaenoic VLCFA formed by elongation and desaturation of the substrate, and C14-24 saturated, C16-24 monoenoic, C18-24 dienoic, C18-22 trienoic and C20-24 tetraenoic fatty acids formed from released [1-14C]acetate either by synthesis de novo or by elongation of endogenous fatty acids. The data suggest that polyenoic VLCFA are synthesized in brain from shorter-chain precursor fatty acids and undergo beta-oxidation.

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Becker, Klaus, James Dick, Douglas Tocher y Christian Schlechtriem. "Incorporation and metabolism of fatty acids by desaturation and elongation in the nematode, Panagrellus redivivus". Nematology 6, n.º 6 (2004): 783–95. http://dx.doi.org/10.1163/1568541044038560.

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AbstractThe free-living nematode Panagrellus redivivus can be mass produced in monoxenic solid culture on Saccharomyces cerevisiae and therefore could be useful as a live food for marine fish or crustacean larvae in the rapidly expanding aquaculture industry. However, this will depend on their lipid and fatty acid composition and so this was investigated in mass produced P. redivivus grown on S. cerevisiae in three different media. Live nematodes were also incubated with [1-14C]-labelled fatty acids and the desaturation and elongation of the fatty acids were determined. The combined results from the growth trials on different media and the metabolic studies with labelled fatty acids indicated the presence of Δ9, Δ12, Δ6 and Δ5 fatty acid desaturase activities, and elongase activities active towards C18, C16 and shorter chain fatty acids. The presence of Δ15, and therefore the ability to produce n-3 polyunsaturated fatty acids, was suggested by the compositional data, but could not be conclusively established from metabolic studies.

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Subrahmanyam, Satyanarayana y John E. Cronan. "Overproduction of a Functional Fatty Acid Biosynthetic Enzyme Blocks Fatty Acid Synthesis inEscherichia coli". Journal of Bacteriology 180, n.º 17 (1 de septiembre de 1998): 4596–602. http://dx.doi.org/10.1128/jb.180.17.4596-4602.1998.

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ABSTRACT β-Ketoacyl-acyl carrier protein (ACP) synthetase II (KAS II) is one of three Escherichia coli isozymes that catalyze the elongation of growing fatty acid chains by condensation of acyl-ACP with malonyl-ACP. Overexpression of this enzyme has been found to be extremely toxic to E. coli, much more so than overproduction of either of the other KAS isozymes, KAS I or KAS III. The immediate effect of KAS II overproduction is the cessation of phospholipid synthesis, and this inhibition is specifically due to the blockage of fatty acid synthesis. To determine the cause of this inhibition, we examined the intracellular pools of ACP, coenzyme A (CoA), and their acyl thioesters. Although no significant changes were detected in the acyl-ACP pools, the CoA pools were dramatically altered by KAS II overproduction. Malonyl-CoA increased to about 40% of the total cellular CoA pool upon KAS II overproduction from a steady-state level of around 0.5% in the absence of KAS II overproduction. This finding indicated that the conversion of malonyl-CoA to fatty acids had been blocked and could be explained if either the conversion of malonyl-CoA to malonyl-ACP and/or the elongation reactions of fatty acid synthesis had been blocked. Overproduction of malonyl-CoA:ACP transacylase, the enzyme catalyzing the conversion of malonyl-CoA to malonyl-ACP, partially relieved the toxicity of KAS II overproduction, consistent with a model in which high levels of KAS II blocks access of the other KAS isozymes to malonyl-CoA:ACP transacylase.

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17

Wang, Zhen, Dong Hao Wang, Hui Gyu Park, Yuanyuan Yan, Yuliya Goykhman, Peter Lawrence, Kumar S. D. Kothapalli y J. Thomas Brenna. "Identification of genes mediating branched chain fatty acid elongation". FEBS Letters 593, n.º 14 (30 de mayo de 2019): 1807–17. http://dx.doi.org/10.1002/1873-3468.13451.

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18

Muci, Maria R., Gino Vonghia y Gabriele V. Gnoni. "Fatty acid chain elongation synthesis in eel-liver Microsomes". Comparative Biochemistry and Physiology Part B: Comparative Biochemistry 101, n.º 1-2 (enero de 1992): 29–33. http://dx.doi.org/10.1016/0305-0491(92)90154-j.

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19

Lee, Hong Gil, Bo-Yeon Park, Hyun Uk Kim y Pil Joon Seo. "MYB96 stimulates C18 fatty acid elongation in Arabidopsis seeds". Plant Biotechnology Reports 9, n.º 3 (28 de abril de 2015): 161–66. http://dx.doi.org/10.1007/s11816-015-0352-9.

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20

Koike, Ryoko, Shoji Tsuji, Tsukasa Ohno, Yasuyuki Suzuki, Tadao Orii y Tadashi Miyatake. "Physiological significance of fatty acid elongation system in adrenoleukodystrophy". Journal of the Neurological Sciences 103, n.º 2 (junio de 1991): 188–94. http://dx.doi.org/10.1016/0022-510x(91)90163-2.

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21

Shi, Wang, Luo, Liu, Loor y Liu. "Fatty Acid Elongase 7 (ELOVL7) Plays a Role in the Synthesis of Long-Chain Unsaturated Fatty Acids in Goat Mammary Epithelial Cells". Animals 9, n.º 6 (25 de junio de 2019): 389. http://dx.doi.org/10.3390/ani9060389.

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In humans, fatty acid elongase 7 (ELOVL7) plays a role in synthesis of long-chain saturated fatty acids. Whether ELOVL7 protein plays a role in ruminants is unclear. The transcript abundance of ELOVL7 in goat mammary tissue was assessed at three stages of lactation. Results showed that ELOVL7 had the highest expression in the dry period compared with peak and late lactation period. Results revealed that ELOVL7 overexpression was correlated with lower expression in diacylglycerol O-acyltransferase 2 (DGAT2) and stearoyl-CoA desaturase 1 (SCD1), and had no significant effect on triacylglycerol concentration. Overexpression of ELOVL7 significantly decreased the concentration of palmitoleic (C16:1n7) and oleic (C18:1n9) acid, and increased the concentration of vaccenic (C18:1n7) and linoleic (C18:2) acid. Overexpression of ELOVL7 significantly upregulated the elongation index of C16:1 in goat epithelial mammary cells (GMEC), but had a minor effect on that of palmitate (C16:0). Knockdown of ELOVL7 decreased mRNA expression of fatty acid binding protein 3 (FABP3) and fatty acid desaturase 2 (FADS2) and had a minor effect on triacylglycerol concentration; however, it increased concentration of C18:1n9 in GMEC. The elongation indices of C16:0 and C16:1 did not differ due to knockdown of ELOVL7. The minor change for the C16:0 and stearate (C18:0) was observed after activation of ELOVL7, suggesting the two fatty acids are not the preferential substrates of ELOVL7 in cultured GMEC. However, changes in C18:1n9 and C18:2 after overexpression or knockdown of ELOVL7 indicated a biological functional role of ELOVL7. Collectively, our data highlighted a role of ELOVL7 in long-chain unsaturated fatty acid elongation in goat mammary epithelial cells.

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Street, J. M., D. W. Johnson, H. Singh y A. Poulos. "Metabolism of saturated and polyunsaturated fatty acids by normal and Zellweger syndrome skin fibroblasts". Biochemical Journal 260, n.º 3 (15 de junio de 1989): 647–55. http://dx.doi.org/10.1042/bj2600647.

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The metabolism of 1-11C-labelled derivatives of palmitic (C16:0), arachidonic (C20:4,n-6) lignoceric (C21:0) and tetracosatetraenoic (C24:4,n-6) acids was studied in normal skin fibroblast cultures and in cultures of fibroblasts from peroxisome-deficient (Zellweger's syndrome) patients. Radiolabelled products of the fatty acids included carbon dioxide. C14-24 saturated and mono-unsaturated fatty acids formed from released acetate either by synthesis de novo or by elongation of endogenous fatty acids, fatty acids formed by 2-6-carbon elongation of added substrates, and a number of water-soluble compounds, some of which were tentatively identified as the amino acids glutamine, glutamic acid and asparagine. The labelled amino acids were found predominantly in the culture medium. Zellweger's syndrome fibroblasts showed a marked decrease in radiolabelled carbon dioxide and water-soluble-product formation from (I-14C)-labelled arachidonic, tetracosatetraenoic and lignoceric acids but not from [I-14C]palmitic acid, and the production of radiolabelled C14-18 fatty acids was also diminished. However, the elongation of individual fatty acids was either normal or above normal. Our data support the view that the oxidation of 20:4, 24:4 and 24:0 fatty acids in cultured skin fibroblasts takes place largely in peroxisomes, and further that the acetyl-CoA released by the beta-oxidation process is available for the synthesis of fatty acids and amino acids. We speculate that the generation of C2 units used for synthesis is a major peroxisomal function and that this function is absent or greatly impaired in Zellweger's syndrome cells.

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Tomčala, Aleš, Jan Michálek, Ivana Schneedorferová, Zoltán Füssy, Ansgar Gruber, Marie Vancová y Miroslav Oborník. "Fatty Acid Biosynthesis in Chromerids". Biomolecules 10, n.º 8 (24 de julio de 2020): 1102. http://dx.doi.org/10.3390/biom10081102.

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Fatty acids are essential components of biological membranes, important for the maintenance of cellular structures, especially in organisms with complex life cycles like protozoan parasites. Apicomplexans are obligate parasites responsible for various deadly diseases of humans and livestock. We analyzed the fatty acids produced by the closest phototrophic relatives of parasitic apicomplexans, the chromerids Chromera velia and Vitrella brassicaformis, and investigated the genes coding for enzymes involved in fatty acids biosynthesis in chromerids, in comparison to their parasitic relatives. Based on evidence from genomic and metabolomic data, we propose a model of fatty acid synthesis in chromerids: the plastid-localized FAS-II pathway is responsible for the de novo synthesis of fatty acids reaching the maximum length of 18 carbon units. Short saturated fatty acids (C14:0–C18:0) originate from the plastid are then elongated and desaturated in the cytosol and the endoplasmic reticulum. We identified giant FAS I-like multi-modular enzymes in both chromerids, which seem to be involved in polyketide synthesis and fatty acid elongation. This full-scale description of the biosynthesis of fatty acids and their derivatives provides important insights into the reductive evolutionary transition of a phototropic algal ancestor to obligate parasites.

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24

Baldwin, A., D. Francis, H. J. Rogers y J. L. Harwood. "The inhibition of fatty acid elongation by pebulate can be effectively counteracted by the safener dichlormid". Biochemical Society Transactions 28, n.º 6 (1 de diciembre de 2000): 650–51. http://dx.doi.org/10.1042/bst0280650.

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The thiocarbamate herbicide pebulate inhibits fatty acid elongation, which is necessary for surface lipid biosynthesis. As both barley and wild oats are susceptible to pebulate, the safener dichlormid was used to study the reversal of its herbicidal effect. Fatty acid elongation was restored by a dichlormid pretreatment in barley, but not in pebulate-expressed oats.

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CUNNANE, STEPHEN C., SUJATA GANGULI, JULIA K. ARMSTRONG y PAUL A. STITT. "RAISED OMEGA-3 FATTY ACID LEVELS IN PIGS FED FLAX". Canadian Journal of Animal Science 70, n.º 1 (1 de marzo de 1990): 251–54. http://dx.doi.org/10.4141/cjas90-029.

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Young growing pigs fed a creep feed containing 5% flax for 8 wk had significantly higher amounts of omega-3 fatty acids in liver, kidney, heart, skin, subcutaneous adipose tissue, and muscle than pigs fed the same diet containing no flax. Increased amounts of desaturation-elongation products of alpha-linolenic acid were observed in liver, heart, kidney and brain. Key words: Flax, alpha-linolenic acid, eicosapentaenoic acid, linoleic acid, arachidonic acid

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Ajie, H. O., M. J. Connor, W. N. Lee, S. Bassilian, E. A. Bergner y L. O. Byerley. "In vivo study of the biosynthesis of long-chain fatty acids using deuterated water". American Journal of Physiology-Endocrinology and Metabolism 269, n.º 2 (1 de agosto de 1995): E247—E252. http://dx.doi.org/10.1152/ajpendo.1995.269.2.e247.

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To determine the contributions of preexisting fatty acid, de novo synthesis, and chain elongation in long-chain fatty acid (LCFA) synthesis, the synthesis of LCFAs, palmitate (16:0), stearate (18:0), arachidate (20:0), behenate (22:0), and lignocerate (24:0), in the epidermis, liver, and spinal cord was determined using deuterated water and mass isotopomer distribution analysis in hairless mice and Sprague-Dawley rats. Animals were given 4% deuterated water for 5 days or 8 wk in their drinking water. Blood was withdrawn at the end of these times for the determination of deuterium enrichment, and the animals were killed to isolate the various tissues for lipid extraction for the determination of the mass isotopomer distributions. The mass isotopomer distributions in LCFA were incompatible with synthesis from a single pool of primer. The synthesis of palmitate, stearate, arachidate, behenate, and lignocerate followed the expected biochemical pathways for the synthesis of LCFAs. On average, three deuterium atoms were incorporated for every addition of an acetyl unit. The isotopomer distribution resulting from chain elongation and de novo synthesis can be described by the linear combination of two binomial distributions. The proportions of preexisting, chain elongation, and de novo-synthesized fatty acids as a percentage of the total fatty acids were determined using multiple linear regression analysis. Fractional synthesis was found to vary, depending on the tissue type and the fatty acid, from 47 to 87%. A substantial fraction (24-40%) of the newly synthesized molecules was derived from chain elongation of unlabeled (recycled) palmitate.

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27

Street, J. M., H. Singh y A. Poulos. "Metabolism of saturated and polyunsaturated very-long-chain fatty acids in fibroblasts from patients with defects in peroxisomal β-oxidation". Biochemical Journal 269, n.º 3 (1 de agosto de 1990): 671–77. http://dx.doi.org/10.1042/bj2690671.

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The metabolism of [1-14C]lignoceric acid (C24:0) and [1-14C]tetracosatetraenoic acid (C24:4, n-6) was studied in normal skin fibroblast cultures and in cultures from patients with defects in peroxisomal β-oxidation (but normal peroxisomal numbers). Cells from X-linked adrenoleukodystrophy (ALD) patients with a presumed defect in a peroxisomal acyl-CoA synthetase, specific for fatty acids of carbon chain lengths greater than 22 (very-long-chain fatty acids; VLCFA), showed a relatively normal production of radiolabelled CO2 and water-soluble metabolites from [1-14C]C24:0. However, the products of synthesis from acetate de novo (released by β-oxidation), i.e. C16 and C18 fatty acids, were decreased, and carbon chain elongation of the fatty acid was increased. In contrast, cell lines from two patients with an unidentified lesion in peroxisomal β-oxidation (peroxisomal disease, PD) showed a marked deficiency in CO2 and water-soluble metabolite production, a decreased synthesis of C16 and C18 fatty acids and an increase in carbon chain elongation. The relatively normal β-oxidation activity of ALD cells appears to be related to low uptake of substrate, as a defect in β-oxidation is apparent when measurements are performed on cell suspensions under high uptake conditions. Oxidation of [1-14C]C24:4 was relatively normal in ALD cells and in the cells from one PD patient but abnormal in those from the other. Our data suggest that, despite the deficiency in VLCFA CoA synthetase, ALD cells retain a near normal ability to oxidize both saturated and polyunsaturated VLCFA under some culture conditions. However, acetate released by β-oxidation of the saturated VLCFA and, to a much lesser degree, the polyunsaturated VLCFA, appears to be used preferentially for the production of CO2 and water-soluble products, and acetate availability for fatty acid synthesis in other subcellular compartments is markedly decreased. It is likely that the increased carbon chain elongation of the saturated VLCFA which is also observed reflects the increased availability of substrate (C24:0) and/or an increase in microsomal elongation activity in ALD cells.

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28

Sharp, P., A. Poulos, A. Fellenberg y D. Johnson. "Structure and lipid distribution of polyenoic very-long-chain fatty acids in the brain of peroxisome-deficient patients (Zellweger syndrome)". Biochemical Journal 248, n.º 1 (15 de noviembre de 1987): 61–67. http://dx.doi.org/10.1042/bj2480061.

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The polyenoic fatty acids with carbon chain lengths from 26 to 38 (very-long-chain fatty acids, VLCFA) previously detected in abnormal amounts in Zellweger syndrome brain have been shown to be n-6 derivatives and therefore probably derived by chain elongation of shorter-chain n-6 fatty acids such as linoleic acid and arachidonic acid. Polyenoic VLCFA are also present in Zellweger syndrome liver, but this tissue differs significantly from brain in that the saturated and mono-unsaturated derivatives are the major VLCFA. Zellweger syndrome brain polyenoic VLCFA are present in the neutral lipids predominantly in cholesterol esters, with smaller amounts in the non-esterified fatty acid and triacylglycerol fractions. These fatty acids are barely detectable in any of the major phospholipids, but are present in significant amounts in an unidentified minor phospholipid. The polyenoic VLCFA composition of this lipid differs markedly from that observed for all other lipids, as it contains high proportions of pentaenoic and hexaenoic fatty acids with 34, 36 and 38 carbon atoms. A polar lipid with the chromatographic properties in normal brain contains similar fatty acids. It is postulated that the polyenoic VLCFA may play an important role in normal brain and accumulate in Zellweger syndrome brain because of a deficiency in the peroxisomal beta-oxidation pathway, although a possible peroxisomal role in the control of carbon-chain elongation cannot be discounted.

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29

Hodson, Leanne, Siobhán E. McQuaid, Sandy M. Humphreys, Ross Milne, Barbara A. Fielding, Keith N. Frayn y Fredrik Karpe. "Greater dietary fat oxidation in obese compared with lean men: an adaptive mechanism to prevent liver fat accumulation?" American Journal of Physiology-Endocrinology and Metabolism 299, n.º 4 (octubre de 2010): E584—E592. http://dx.doi.org/10.1152/ajpendo.00272.2010.

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Liver fat represents a balance between input, secretion, and oxidation of fatty acids. As humans spend the majority of a 24-h period in a postprandial state, dietary fatty acids make an important contribution to liver fat metabolism. We compared hepatic fatty acid partitioning in healthy lean ( n = 9) and abdominally obese ( n = 10) males over 24 h. Volunteers received three mixed meals adjusted for basal metabolic rate. U-13C-labeled fatty acids were incorporated into the meals, and [2H2]palmitate was infused intravenously to distinguish between sources of fatty acids incorporated into VLDL-TG. Immunoaffinity chromatography was used to isolate VLDL-TG of hepatic origin. Liver and whole body fatty acid oxidation was assessed by isotopic enrichment of 3-hydoxybutyrate and breath CO2.We found a similar contribution of dietary fatty acids to VLDL-TG in the two groups over 24 h. The contribution of fatty acids from splanchnic sources was higher ( P < 0.05) in the abdominally obese group. Ketogenesis occurred to a significantly greater extent in abdominally obese compared with lean males, largely due to lessened downregulation of postprandial ketogenesis ( P < 0.001). The appearance of13C in breath CO2was also greater ( P < 0.001) in abdominally obese compared with lean men. Hepatic elongation and desaturation of palmitic acid were higher ( P < 0.05) in abdominally obese than in lean males. Oxidation of dietary fatty acids and hepatic desaturation and elongation of palmitic acid occurred to a greater extent in abdominally obese men. These alterations may represent further pathways for redirection of fatty acids into export from the liver or oxidation to prevent liver fat accumulation.

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30

Zimhony, Oren, Catherine Vilchèze y William R. Jacobs. "Characterization of Mycobacterium smegmatis Expressing the Mycobacterium tuberculosis Fatty Acid Synthase I (fas1) Gene". Journal of Bacteriology 186, n.º 13 (1 de julio de 2004): 4051–55. http://dx.doi.org/10.1128/jb.186.13.4051-4055.2004.

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ABSTRACT Unlike most other bacteria, mycobacteria make fatty acids with the multidomain enzyme eukaryote-like fatty acid synthase I (FASI). Previous studies have demonstrated that the tuberculosis drug pyrazinamide and 5-chloro-pyrazinamide target FASI activity. Biochemical studies have revealed that in addition to C16:0, Mycobacterium tuberculosis FASI synthesizes C26:0 fatty acid, while the Mycobacterium smegmatis enzyme makes C24:0 fatty acid. In order to express M. tuberculosis FASI in a rapidly growing Mycobacterium and to characterize the M. tuberculosis FASI in vivo, we constructed an M. smegmatis Δfas1 strain which contained the M. tuberculosis fas1 homologue. The M. smegmatis Δfas1 (attB::M. tuberculosis fas1) strain grew more slowly than the parental M. smegmatis strain and was more susceptible to 5-chloro-pyrazinamide. Surprisingly, while the M. smegmatis Δfas1 (attB::M. tuberculosis fas1) strain produced C26:0, it predominantly produced C24:0. These results suggest that the fatty acid elongation that produces C24:0 or C26:0 in vivo is due to a complex interaction among FASI, FabH, and FASII and possibly other systems and is not solely due to FASI elongation, as previously suggested by in vitro studies.

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31

Sun, Shouxiang, Yumei Wang, Pei-Tian Goh, Mónica Lopes-Marques, L. Filipe C. Castro, Óscar Monroig, Meng-Kiat Kuah, Xiaojuan Cao, Alexander Chong Shu-Chien y Jian Gao. "Evolution and Functional Characteristics of the Novel elovl8 That Play Pivotal Roles in Fatty Acid Biosynthesis". Genes 12, n.º 8 (23 de agosto de 2021): 1287. http://dx.doi.org/10.3390/genes12081287.

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Elongation of very long-chain fatty acid (Elovl) proteins are key enzymes that catalyze the rate-limiting step in the fatty acid elongation pathway. The most recently discovered member of the Elovl family, Elovl8, has been proposed to be a fish-specific elongase with two gene paralogs described in teleosts. However, the biological functions of Elovl8 are still to be elucidated. In this study, we showed that in contrast to previous findings, elovl8 is not unique to teleosts, but displays a rather unique and ample phylogenetic distribution. For functional determination, we generated elovl8a (elovl8a−/−) and elovl8b (elovl8b−/−) zebrafish using CRISPR/Cas9 technology. Fatty acid composition in vivo and zebrafish liver cell experiments suggest that the substrate preference of Elovl8 overlapped with other existing Elovl enzymes. Zebrafish Elovl8a could elongate the polyunsaturated fatty acids (PUFAs) C18:2n-6 and C18:3n-3 to C20:2n-6 and C20:3n-3, respectively. Along with PUFA, zebrafish Elovl8b also showed the capacity to elongate C18:0 and C20:1. Gene expression quantification suggests that Elovl8a and Elovl8b may play a potentially important role in fatty acid biosynthesis. Overall, our results provide novel insights into the function of Elovl8a and Elovl8b, representing additional fatty acid elongases not previously described in chordates.

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32

Fritzler, Jason M., Jason J. Millership y Guan Zhu. "Cryptosporidium parvum Long-Chain Fatty Acid Elongase". Eukaryotic Cell 6, n.º 11 (7 de septiembre de 2007): 2018–28. http://dx.doi.org/10.1128/ec.00210-07.

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ABSTRACT We report the presence of a new fatty acyl coenzyme A (acyl-CoA) elongation system in Cryptosporidium and the functional characterization of the key enzyme, a single long-chain fatty acid elongase (LCE), in this parasite. This enzyme contains conserved motifs and predicted transmembrane domains characteristic to the elongase family and is placed within the ELO6 family specific for saturated substrates. CpLCE1 gene transcripts are present at all life cycle stages, but the levels are highest in free sporozoites and in stages at 36 h and 60 h postinfection that typically contain free merozoites. Immunostaining revealed localization to the outer surface of sporozoites and to the parasitophorous vacuolar membrane. Recombinant CpLCE1 displayed allosteric kinetics towards malonyl-CoA and palmitoyl-CoA and Michaelis-Menten kinetics towards NADPH. Myristoyl-CoA (C14:0) and palmitoyl-CoA (C16:0) display the highest activity when used as substrates, and only one round of elongation occurs. CpLCE1 is fairly resistant to cerulenin, an inhibitor for both type I and II fatty acid synthases (i.e., maximum inhibitions of 20.5% and 32.7% were observed when C16:0 and C14:0 were used as substrates, respectively). These observations ultimately validate the function of CpLCE1.

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33

Roke, Kaitlin, Sebastian Jannas-Vela, Lawrence L. Spriet y David M. Mutch. "FADS2 genotype influences whole-body resting fat oxidation in young adult men". Applied Physiology, Nutrition, and Metabolism 41, n.º 7 (julio de 2016): 791–94. http://dx.doi.org/10.1139/apnm-2016-0043.

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Considerable evidence supports an association between fatty acid desaturase 2 (FADS2) polymorphisms and the efficiency of converting alpha-linolenic acid (ALA) into eicosapentaenoic acid (EPA) via the desaturation–elongation pathway. However, ALA conversion into EPA represents only 1 of the metabolic fates for this essential fatty acid, as ALA is also highly oxidized. This study demonstrates for the first time that genetic variation in FADS2 (rs174576) is not only associated with the activity of the desaturation–elongation pathway, but also whole-body fat oxidation.

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34

Kessler, Sonja, Yvette Simon, Katja Gemperlein, Kathrin Gianmoena, Cristina Cadenas, Vincent Zimmer, Juliane Pokorny et al. "Fatty Acid Elongation in Non-Alcoholic Steatohepatitis and Hepatocellular Carcinoma". International Journal of Molecular Sciences 15, n.º 4 (4 de abril de 2014): 5762–73. http://dx.doi.org/10.3390/ijms15045762.

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35

Barrett, Philippa B. y John L. Harwood. "Naphthalic anhydride prevents inhibition of fatty acid elongation by thiocarbamates". Phytochemistry 49, n.º 7 (diciembre de 1998): 1897–903. http://dx.doi.org/10.1016/s0031-9422(98)00377-x.

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36

Haslam, Tegan M. y Ljerka Kunst. "Extending the story of very-long-chain fatty acid elongation". Plant Science 210 (septiembre de 2013): 93–107. http://dx.doi.org/10.1016/j.plantsci.2013.05.008.

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37

Oosterveer, Maaike H., Theo H. van Dijk, Uwe J. F. Tietge, Theo Boer, Rick Havinga, Frans Stellaard, Albert K. Groen, Folkert Kuipers y Dirk-Jan Reijngoud. "High Fat Feeding Induces Hepatic Fatty Acid Elongation in Mice". PLoS ONE 4, n.º 6 (26 de junio de 2009): e6066. http://dx.doi.org/10.1371/journal.pone.0006066.

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38

Kerner, Janos, Paul E. Minkler, Edward J. Lesnefsky y Charles L. Hoppel. "Fatty Acid Chain Elongation in Palmitate-perfused Working Rat Heart". Journal of Biological Chemistry 289, n.º 14 (20 de febrero de 2014): 10223–34. http://dx.doi.org/10.1074/jbc.m113.524314.

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39

Cinti, Dominick L., Lynda Cook, Mahmod N. Nagi y Sanoj K. Suneja. "The fatty acid chain elongation system of mammalian endoplasmic reticulum". Progress in Lipid Research 31, n.º 1 (enero de 1992): 1–51. http://dx.doi.org/10.1016/0163-7827(92)90014-a.

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40

Kugi, Mari, Satoshi Yoshida y Masazumi Takeshita. "Characterization of fatty acid elongation system in porcine neutrophil microsomes". Biochimica et Biophysica Acta (BBA) - Lipids and Lipid Metabolism 1043, n.º 1 (marzo de 1990): 83–90. http://dx.doi.org/10.1016/0005-2760(90)90113-c.

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41

McKeon, Thomas A., Marta Goodrich-Tanrikulu, Jiann-Tsyh Lin y Allan Stafford. "Pathways for fatty acid elongation and desaturation in Neurospora crassa". Lipids 32, n.º 1 (enero de 1997): 1–5. http://dx.doi.org/10.1007/s11745-997-0001-8.

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42

Balzano, Sergio, Laura Villanueva, Marijke de Bar, Diana X. Sahonero Canavesi, Caglar Yildiz, Julia C. Engelmann, Eric Marechal, Josselin Lupette, Jaap S. Sinninghe Damstï¿½ y Stefan Schouten. "Biosynthesis of Long Chain Alkyl Diols and Long Chain Alkenols in Nannochloropsis spp. (Eustigmatophyceae)". Plant and Cell Physiology 60, n.º 8 (6 de mayo de 2019): 1666–82. http://dx.doi.org/10.1093/pcp/pcz078.

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AbstractWe investigated potential biosynthetic pathways of long chain alkenols (LCAs), long chain alkyl diols (LCDs), and long chain hydroxy fatty acids (LCHFAs) in Nannochloropsis oceanica and Nannochloropsis gaditana, by combining culturing experiments with genomic and transcriptomic analyses. Incubation of Nannochloropsis spp. in the dark for 1 week led to significant increases in the cellular concentrations of LCAs and LCDs in both species. Consistently, 13C-labelled substrate experiments confirmed that both LCA and LCD were actively produced in the dark from C14–18 fatty acids by either condensation or elongation/hydroxylation, although no enzymatic evidence was found for the former pathway. Nannochloropsis spp. did, however, contain (i) multiple polyketide synthases (PKSs) including one type (PKS-Clade II) that might catalyze incomplete fatty acid elongations leading to the formation of 3-OH-fatty acids, (ii) 3-hydroxyacyl dehydratases (HADs), which can possibly form Δ2/Δ3 monounsaturated fatty acids, and (iii) fatty acid elongases (FAEs) that could elongate 3-OH-fatty acids and Δ2/Δ3 monounsaturated fatty acids to longer products. The enzymes responsible for reduction of the long chain fatty acids to LCDs and LCAs are, however, unclear. A putative wax ester synthase/acyl coenzyme A (acyl-CoA): diacylglycerol acyltransferase is likely to be involved in the esterification of LCAs and LCDs in the cell wall. Our data thus provide useful insights in predicting the biosynthetic pathways of LCAs and LCDs in phytoplankton suggesting a key role of FAE and PKS enzymes.

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43

March, B. E. "Essential fatty acids in fish physiology". Canadian Journal of Physiology and Pharmacology 71, n.º 9 (1 de septiembre de 1993): 684–89. http://dx.doi.org/10.1139/y93-102.

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This paper emphasizes those aspects of fatty acid research in fish that have relevance to the investigation of the functions of essential fatty acids in other species. Lipid requirements of fish came under investigation only in the 1960s. The most significant finding has been the requirement for n − 3 fatty acids. The dietary ratio of (n − 3):(n − 6) is critical if the essential requirement is met by C18 fatty acids because of competition between fatty acids for the enzymes involved in elongation and desaturation to produce the physiologically essential long-chain fatty acids. The fatty acid composition of fish lipids varies according to the fatty acid profile of the dietary lipid. The fatty acid composition of fish also responds to temperature changes in an adaptive mechanism for maintenance of membrane homeoviscosity and physiological function over a range of temperatures. The dietary intake of essential fatty acids by brood stock must be adequate for ova formation and for embryonic development, with the latter requirement being more critical for reproductive success. Absolute requirements of fish for essential fatty acids are difficult to define and may vary depending upon the dietary ratio of (n − 3) to (n − 6) fatty acids.Key words: essential fatty acids, nutritive requirements, fish.

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44

Ferreri, Carla, Anna Sansone, Sandra Buratta, Lorena Urbanelli, Eva Costanzi, Carla Emiliani y Chryssostomos Chatgilialoglu. "The n-10 Fatty Acids Family in the Lipidome of Human Prostatic Adenocarcinoma Cell Membranes and Extracellular Vesicles". Cancers 12, n.º 4 (7 de abril de 2020): 900. http://dx.doi.org/10.3390/cancers12040900.

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A new pathway leading to the n-10 fatty acid series has been recently evidenced, starting from sapienic acid, a monounsaturated fatty acid (MUFA) resulting from the transformation of palmitic acid by delta-6 desaturase. Sapienic acid has attracted attention as a novel marker of cancer cell plasticity. Here, we analyzed fatty acids, including the n-10 fatty acid contents, and for the first time, compared cell membranes and the corresponding extracellular vesicles (EV) of two human prostatic adenocarcinoma cell lines of different aggressiveness (PC3 and LNCaP). The n-10 components were 9–13% of the total fatty acids in both cancer cell lines and EVs, with total MUFA levels significantly higher in EVs of the most aggressive cell type (PC3). High sapienic/palmitoleic ratios indicated the preference for delta-6 versus delta-9 desaturase enzymatic activity in these cell lines. The expressions analysis of enzymes involved in desaturation and elongation by qRT-PCR showed a higher desaturase activity in PC3 and a higher elongase activity toward polyunsaturated fatty acids than toward saturated fatty acids, compared to LNCaP cells. Our results improve the present knowledge in cancer fatty acid metabolism and lipid phenotypes, highlighting EV lipidomics to monitor positional fatty acid isomer profiles and MUFA levels in cancer.

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45

PEREIRA, Suzette L., Amanda E. LEONARD, Yung-Sheng HUANG, Lu-Te CHUANG y Pradip MUKERJI. "Identification of two novel microalgal enzymes involved in the conversion of the ω3-fatty acid, eicosapentaenoic acid, into docosahexaenoic acid". Biochemical Journal 384, n.º 2 (23 de noviembre de 2004): 357–66. http://dx.doi.org/10.1042/bj20040970.

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Marine microalgae such as Pavlova and Isochrysis produce abundant amounts of the ω3-PUFAs (polyunsaturated fatty acids), EPA (eicosapentaenoic acid, 20:5n–3) and DHA (docosahexaenoic acid, 22:6n–3). The pathway leading to the conversion of EPA into DHA in these lower eukaryotes is not well established although it is predicted to involve an elongation step, catalysed by an elongating enzyme complex, leading to the conversion of EPA into ω3-DPA (ω–3-docosapentaenoic acid, 22:5n–3); followed by a desaturation step, catalysed by a Δ4-desaturase, which results in the conversion of DPA into DHA. To date, the enzymes involved in the elongation of EPA have not been identified from any lower eukaryote. In the present study, we describe the identification of microalgal genes involved in the two-step conversion of EPA into DHA. By expressed sequence tag analysis, a gene (pavELO) encoding a novel elongase was identified from Pavlova, which catalysed the conversion of EPA into ω3-DPA in yeast. Unlike any previously identified elongase from higher or lower eukaryotes, this enzyme displayed unique substrate specificity for both n–6 and n–3 C20-PUFA substrates, with no activity towards any C18- or C22-PUFA substrates. In addition, a novel Δ4-desaturase gene (IgD4) was isolated from Isochrysis, which was capable of converting ω3-DPA into DHA, as well as adrenic acid (22:4n–6) into ω6-DPA. Yeast co-expression studies, with pavELO and IgD4, revealed that these genes were capable of functioning together to carry out the two-step conversion of EPA into DHA.

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46

Schindler, Maria, Dirk Dannenberger, Gerd Nuernberg, Mareike Pendzialek, Katarzyna Grybel, Tom Seeling y Anne Navarrete Santos. "Embryonic fatty acid metabolism in diabetic pregnancy: the difference between embryoblasts and trophoblasts". Molecular Human Reproduction 26, n.º 11 (26 de septiembre de 2020): 837–49. http://dx.doi.org/10.1093/molehr/gaaa063.

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Abstract During the first days of development the preimplantation embryo is supplied with nutrients from the surrounding milieu. Maternal diabetes mellitus affects the uterine microenvironment, leading to a metabolic adaptation processes in the embryo. We analysed embryonic fatty acid (FA) profiles and expression of processing genes in rabbit blastocysts, separately in embryoblasts (EBs) and trophoblasts (TBs), to determine the potential consequences of maternal diabetes mellitus on intracellular FA metabolism. Insulin-dependent diabetes was induced by alloxan in female rabbits. On Day 6 post coitum, FA profiles in blastocysts (EB, TB and blastocoel fluid) and maternal blood were analysed by gas chromatography. The expression levels of molecules involved in FA elongation (fatty acid elongases, ELOVLs) and desaturation (fatty acid desaturases, FADSs) were measured in EB and TB. Maternal diabetes mellitus influenced the FA profile in maternal plasma and blastocysts. Independent from metabolic changes, rabbit blastocysts contained a higher level of saturated fatty acids (SFAs) and a lower level of polyunsaturated fatty acids (PUFAs) compared to the FA profile of the maternal plasma. Furthermore, the FA profile was altered in the EB and TB, differently. While SFAs (palmitic and stearic acid) were elevated in EB of diabetic rabbits, PUFAs, such as docosahexaenoic acid, were decreased. In contrast, in the TB, lower levels of SFAs and higher levels of oleic acid were observed. EB and TB specific alterations in gene expression were found for ELOVLs and FADSs, key enzymes for FA elongation and desaturation. In conclusion, maternal diabetes mellitus alters embryonic FA metabolism differently in EB and TB, indicating a lineage-specific metabolic adaptive response.

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47

Walker, K. A. y J. L. Harwood. "Evidence for separate elongation enzymes for very-long-chain-fatty-acid synthesis in potato (Solanum tuberosum)". Biochemical Journal 237, n.º 1 (1 de julio de 1986): 41–46. http://dx.doi.org/10.1042/bj2370041.

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Aging potato (Solanum tuberosum) tuber discs in a Ca2+-containing medium resulted in increased rates of fatty acid labelling from [1-14C]acetate with time. Maximal labelling rates were seen after 6-8 h aging in a number of varieties. Saturated very-long-chain fatty acids (C20 and particularly C22 and C24) were very poorly labelled in freshly cut tissue. They were synthesized in increasing amounts and in a homologous sequence with progressive aging times. Use of increasing induction times and cycloheximide or puromycin as protein-synthesis inhibitors indicated that the sequence of fatty acid elongation was dependent on protein synthesis de novo and was controlled by three separate specific elongase enzymes.

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48

Rakotomanga, M., M. Saint-Pierre-Chazalet y P. M. Loiseau. "Alteration of Fatty Acid and Sterol Metabolism in Miltefosine-Resistant Leishmania donovani Promastigotes and Consequences for Drug-Membrane Interactions". Antimicrobial Agents and Chemotherapy 49, n.º 7 (julio de 2005): 2677–86. http://dx.doi.org/10.1128/aac.49.7.2677-2686.2005.

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ABSTRACT Miltefosine (hexadecylphosphocholine [HePC]) is the first orally active drug approved for the treatment of visceral leishmaniasis. In order to investigate the biochemical modifications occurring in HePC-resistant (HePC-R) Leishmania donovani promastigotes, taking into account the lipid nature of HePC, we investigated their fatty acid and sterol metabolisms. We found that the content of unsaturated phospholipid alkyl chains was lower in HePC-R parasite plasma membranes than in those of the wild type, suggesting a lower fluidity of HePC-R parasite membranes. We also demonstrated that HePC insertion within an external monolayer was more difficult when the proportion of unsaturated phospholipids decreased, rendering the HePC interaction with the external monolayer of HePC-R parasites more difficult. Furthermore, HePC-R parasite membranes displayed a higher content of short alkyl chain fatty acids, suggesting a partial inactivation of the fatty acid elongation enzyme system in HePC-R parasites. Sterol biosynthesis was found to be modified in HePC-R parasites, since the 24-alkylated sterol content was halved in HePC-R parasites; however, this modification was not related to HePC sensitivity. In conclusion, HePC resistance affects three lipid biochemical pathways: fatty acid elongation, the desaturase system responsible for fatty acid alkyl chain unsaturation, and the C-24-alkylation of sterols.

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49

ROTSTEIN, N. P., G. L. PENNACCHIOTTI, H. SPRECHER y M. I. AVELDAÑO. "Active synthesis of C24:5, n-3 fatty acid in retina". Biochemical Journal 316, n.º 3 (15 de junio de 1996): 859–64. http://dx.doi.org/10.1042/bj3160859.

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The formation of 14C-labelled long-chain and very-long-chain (n-3) pentaenoic and hexaenoic fatty acids was studied in bovine retina by following the metabolism of [14C]docosapentaenoate [C22:5, n-3 fatty acid (22:5 n-3)], [14C]docosahexaenoate (22:6 n-3), and [14C]acetate. With similar amounts of 22:5 n-3 and 22:6 n-3 as substrates, the former was actively transformed into 24:5 n-3, whereas the latter was virtually unmodified. Labelled 24:5, 26:5, 24:6 and 22:6 were formed from [1-14C]22:5 n-3, showing that pentaenoic fatty acids including 24:5 n-3 can be elongated and desaturated within the retina. When retinal microsomes were incubated with [1-14C]22:5 n-3, 24:5 n-3 was the only fatty acid formed. In retinas incubated with [14C]acetate, 24:5 n-3 was the most highly labelled fatty acid among the polyenes synthesized, 24:6 n-3 being a minor product. Such selectivity in the elongation of two fatty acids identical in length, 22:5 n-3 and 22:6 n-3, despite the fact that 22:5 is a minor and 22:6 a major fatty acid constituent of retina, suggests that the active formation of 24:5 n-3 plays a key role in n-3 polyunsaturated fatty acid (PUFA) metabolism. This compound might give rise to even longer pentaenes via elongation, and to the major PUFAs of retina, 22:6 n-3, by 6-desaturation and chain shortening. Of all retinal lipids, a minor component, triacylglycerol (TG), incorporated the largest amounts of [14C]22:5 and 22:6. TG also concentrated most of the [14C]24:5 formed in retina, whether from [14C]22:5 n-3 or from [14C]acetate, suggesting an important role for this lipid in supporting PUFA metabolism and the synthesis of 22:6 n-3.

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Engelen, Marc, Martin J. A. Schackmann, Rob Ofman, Robert-Jan Sanders, Inge M. E. Dijkstra, Sander M. Houten, Stéphane Fourcade et al. "Bezafibrate lowers very long-chain fatty acids in X-linked adrenoleukodystrophy fibroblasts by inhibiting fatty acid elongation". Journal of Inherited Metabolic Disease 35, n.º 6 (24 de marzo de 2012): 1137–45. http://dx.doi.org/10.1007/s10545-012-9471-4.

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