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GANGAR, Akanksha, Sumana RAYCHAUDHURI, and Ram RAJASEKHARAN. "Alteration in the cytosolic triacylglycerol biosynthetic machinery leads to decreased cell growth and triacylglycerol synthesis in oleaginous yeast." Biochemical Journal 365, no. 3 (August 1, 2002): 577–89. http://dx.doi.org/10.1042/bj20011654.
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Altered nutrient content (levels of glucose) caused a drastic reduction in cell growth and triacylglycerol (TAG) production in the wild-type (WT) Rhodotorula glutinis. This was due to the decreased level of synthesis of TAG biosynthetic enzymes, reflected by a reduction in enzyme activity. A similar observation was made in the case of non-lethal mutants of TAG-deficient oleaginous yeast, namely TAG1 and TAG2, which were generated by ethyl methane sulphonate mutagenesis. Metabolic labelling of TAG-deficient cells with [14C]acetate, [32P]orthophosphate and [14C]mevalonate showed a negligible TAG formation with minimal alterations in phospholipid and sterol compositions. Assays on the activities of cytosolic TAG biosynthetic enzymes revealed that lysophosphatidic acid and diacylglycerol acyltransferases (ATs) were defective in TAG1 and TAG2 respectively. The activity of membrane-bound isoforms of TAG biosynthetic enzymes remains unaltered in the mutants. Analysis of cytosolic TAG biosynthetic enzymes by immunoblotting and immunoprecipitation indicated that the defective ATs were a part of the TAG biosynthetic multienzyme complex. Quantitatively, the cytosolic lysophosphatidic acid-AT was comparable between TAG1 and the WT. However, diacylglycerol-AT was relatively less in TAG2 than the WT. These results demonstrated that either by decreasing the nutrient content or mutating the enzymes of the soluble TAG biosynthetic pathway, TAG production was decreased with concomitant reduction in the cell growth.
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Roche, Helen M. "Dietary carbohydrates and triacylglycerol metabolism." Proceedings of the Nutrition Society 58, no. 1 (February 1999): 201–7. http://dx.doi.org/10.1079/pns19990026.
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There is a growing body of scientific evidence which demonstrates that plasma triacylglycerol (TAG) concentration, especially in the postprandial state, is an important risk factor in relation to the development of CHD. Postprandial hypertriacylglycerolaemia is associated with a number of adverse metabolic risk factors, including the preponderance of small dense LDL, low HDL-cholesterol concentrations and elevated factor VII activity. Traditionally, a low-fat high-carbohydrate diet was used to prevent CHD because it effectively reduces plasma cholesterol concentrations, but this dietary regimen increases plasma TAG concentrations and reduces HDL-cholesterol concentrations. There is substantial epidemiological evidence which demonstrates that high plasma TAG and low plasma HDL concentrations are associated with an increased risk of CHD. Thus, there is reason for concern that the adverse effects of low-fat high-carbohydrate diets on TAG and HDL may counteract or negate the beneficial effect of reducing LDL-cholesterol concentrations. Although there have been no prospective studies to investigate whether reduced fat intake has an adverse effect on CHD, there is strong epidemiological evidence that reducing total fat intake is not protective against CHD. On the other hand, high-fat diets predispose to obesity, and central obesity adversely affects TAG metabolism. There is substantial evidence that in free-living situations low-fat high-carbohydrate diets lead to weight loss, which in turn will correct insulin resistance and plasma TAG metabolism. Clearly there is a need for prospective studies to resolve the issue as to whether low-fat high-carbohydrate diets play an adverse or beneficial role in relation to the development of CHD.
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Zárubová, M., V. Filip, J. Šmidrkal, T. Kůtek, and I. Piska. "The separation of triacylglycerols using unpolar and medium polar capillary columns." Czech Journal of Food Sciences 22, SI - Chem. Reactions in Foods V (January 1, 2004): S123—S126. http://dx.doi.org/10.17221/10633-cjfs.
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Commercial by supplied triacylglycerols and synthesized triacylglycerols were used in this project. Analysed triacylglycerols with the range of carbon number (CN) 24–54 consisted of saturated and unsaturated fatty acids. Two capillary columns were used in the analyses of triacylglycerols, namely non-polar (Optima<sup>®</sup>-1-TG) and medium polar (Optima<sup>®</sup>-17-TG) types. In this study the effectiveness of separation (A) of triacylglycerols with different carbon number values, (B) of triacylglycerols with different unsaturation degree, (C) of positional isomers were determined and further possibilities to separate another lipid compounds were analysed. The column Optima<sup>®</sup>-17-TG separates TAG according to the degree of unsaturation while the column Optima<sup>®</sup>-1-TG separates saturated and unsaturated TAG. High temperature capillary gas chromatography was used to determine changes in triacylglycerol composition during the transesterification of structured fats.
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Whyte, Martin B., Fariba Shojaee-Moradie, Sharaf E. Sharaf, Nicola C. Jackson, Barbara Fielding, Roman Hovorka, Jeewaka Mendis, David Russell-Jones, and A. Margot Umpleby. "Lixisenatide Reduces Chylomicron Triacylglycerol by Increased Clearance." Journal of Clinical Endocrinology & Metabolism 104, no. 2 (September 11, 2018): 359–68. http://dx.doi.org/10.1210/jc.2018-01176.
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Abstract Context Glucagon-like peptide-1 (GLP-1) agonists control postprandial glucose and lipid excursion in type 2 diabetes; however, the mechanisms are unclear. Objective To determine the mechanisms of postprandial lipid and glucose control with lixisenatide (GLP-1 analog) in type 2 diabetes. Design Randomized, double-blind, cross-over study. Setting Centre for Diabetes, Endocrinology, and Research, Royal Surrey County Hospital, Guildford, United Kingdom. Patients Eight obese men with type 2 diabetes [age, 57.3 ± 1.9 years; body mass index, 30.3 ± 1.0 kg/m2; glycosylated hemoglobin, 66.5 ± 2.6 mmol/mol (8.2% ± 0.3%)]. Interventions Two metabolic studies, 4 weeks after lixisenatide or placebo, with cross-over and repetition of studies. Main Outcome Measures Study one: very-low-density lipoprotein (VLDL) and chylomicron (CM) triacylglycerol (TAG) kinetics were measured with an IV bolus of [2H5]glycerol in a 12-hour study, with hourly feeding. Oral [13C]triolein, in a single meal, labeled enterally derived TAG. Study two: glucose kinetics were measured with [U-13C]glucose in a mixed-meal (plus acetaminophen to measure gastric emptying) and variable IV [6,6-2H2]glucose infusion. Results Study one: CM-TAG (but not VLDL-TAG) pool-size was lower with lixisenatide (P = 0.046). Lixisenatide reduced CM [13C]oleate area under the curve (AUC)60–480min concentration (P = 0.048) and increased CM-TAG clearance, with no effect on CM-TAG production rate. Study two: postprandial glucose and insulin AUC0–240min were reduced with lixisenatide (P = 0.0051; P < 0.05). Total glucose production (P = 0.015), rate of glucose appearance from the meal (P = 0.0098), and acetaminophen AUC0–360min (P = 0.006) were lower with lixisenatide than with placebo. Conclusions Lixisenatide reduced [13C]oleate concentrations, derived from a single meal in CM-TAG and glucose rate of appearance from the meal through delayed gastric emptying. However, day-long CM production, measured with repeated meal feeding, was not reduced by lixisenatide and decreased CM-TAG concentration resulted from increased CM-TAG clearance.
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Gibbons, G. F., D. Wiggins, A. M. Brown, and A. M. Hebbachi. "Synthesis and function of hepatic very-low-density lipoprotein." Biochemical Society Transactions 32, no. 1 (February 1, 2004): 59–64. http://dx.doi.org/10.1042/bst0320059.
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Most of the triacylglycerol (TAG) utilized for the assembly of very-low-density lipoprotein (VLDL) in the secretory apparatus of the hepatocyte is mobilized by lipolysis of the cytosolic TAG pool, followed by re-esterification. The lipases involved include arylacetamide deacetylase and/or triacylglycerol hydrolase. Some of the re-esterified products of lipolysis gain access to an apolipoprotein-B-rich VLDL precursor to form mature VLDL. Some, however, are returned to the cytosolic pool in a process that is stimulated by insulin and inhibited by microsomal triacylglycerol transfer protein (MTP). Phospholipids also contribute to VLDL TAG in a process which involves ADP-ribosylation factor-1 (ARF-1)-mediated activation of phospholipase D. The temporary storage of TAG in the liver, followed by its mobilization and secretion as VLDL, form part of a process by which the liver protects vulnerable body tissues from excess lipotoxic non-esterified (‘free’) fatty acids in the plasma.
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Razul, M. Shajahan G., Colin J. MacDougall, Charles B. Hanna, Alejandro G. Marangoni, Fernanda Peyronel, Erzsebet Papp-Szabo, and David A. Pink. "Oil binding capacities of triacylglycerol crystalline nanoplatelets: nanoscale models of tristearin solids in liquid triolein." Food Funct. 5, no. 10 (2014): 2501–8. http://dx.doi.org/10.1039/c3fo60654f.
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Lu, Junhao, Yang Xu, Juli Wang, Stacy D. Singer, and Guanqun Chen. "The Role of Triacylglycerol in Plant Stress Response." Plants 9, no. 4 (April 8, 2020): 472. http://dx.doi.org/10.3390/plants9040472.
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Vegetable oil is mainly composed of triacylglycerol (TAG), a storage lipid that serves as a major commodity for food and industrial purposes, as well as an alternative biofuel source. While TAG is typically not produced at significant levels in vegetative tissues, emerging evidence suggests that its accumulation in such tissues may provide one mechanism by which plants cope with abiotic stress. Different types of abiotic stress induce lipid remodeling through the action of specific lipases, which results in various alterations in membrane lipid composition. This response induces the formation of toxic lipid intermediates that cause membrane damage or cell death. However, increased levels of TAG under stress conditions are believed to function, at least in part, as a means of sequestering these toxic lipid intermediates. Moreover, the lipid droplets (LDs) in which TAG is enclosed also function as a subcellular factory to provide binding sites and substrates for the biosynthesis of bioactive compounds that protect against insects and fungi. Though our knowledge concerning the role of TAG in stress tolerance is expanding, many gaps in our understanding of the mechanisms driving these processes are still evident. In this review, we highlight progress that has been made to decipher the role of TAG in plant stress response, and we discuss possible ways in which this information could be utilized to improve crops in the future.
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Menon, Jesudas E., David J. Stensel, Keith Tolfrey, and Stephen F. Burns. "Increased Meal Frequency With Exercise Mitigates Postprandial Triacylglycerol." Journal of Physical Activity and Health 16, no. 8 (August 1, 2019): 589–94. http://dx.doi.org/10.1123/jpah.2018-0696.
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Purpose: This study examined how manipulating meal frequency, with and without exercise, affects postprandial triacylglycerol (TAG). Methods: Fourteen sedentary men completed four 2-day trials in a noncounterbalanced random cross-over order: (1) consumption of 1 large high-fat milkshake without exercise (1-CON), (2) consumption of 2 smaller high-fat milkshakes without exercise (2-CON), (3) consumption of 1 large high-fat milkshake with exercise (1-EX), and (4) consumption of 2 small high-fat milkshakes with exercise (2-EX)—total energy intake was standardized across trials. On day 1, participants rested (1-CON and 2-CON) or walked briskly for 60 minutes (1-EX and 2-EX). On day 2, participants consumed either a single large high-fat milkshake (75% fat; 1-CON and 1-EX) for breakfast or 2 smaller isoenergetic milkshakes (2-CON and 2-EX) for breakfast and lunch. Plasma TAG were measured fasting and for 7 hours after breakfast. Results: Peak incremental TAG was 30% lower on 2-EX than 1-CON (P = .04, d = 0.38). Postprandial TAG increased more rapidly in the first 4 hours in 1-CON than other trials; but at 6 hours, TAG was exaggerated in 2-CON compared with 1-CON. Conclusions: Increasing meal frequency after exercise, without altering overall fat intake, attenuates postprandial TAG.
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Lee, Ju-Young, Kwang-Hyeon Liu, Yunhi Cho, and Kun-Pyo Kim. "Enhanced Triacylglycerol Content and Gene Expression for Triacylglycerol Metabolism, Acyl-Ceramide Synthesis, and Corneocyte Lipid Formation in the Epidermis of Borage Oil Fed Guinea Pigs." Nutrients 11, no. 11 (November 18, 2019): 2818. http://dx.doi.org/10.3390/nu11112818.
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Triacylglycerol (TAG) metabolism is related to the acyl-ceramide (Cer) synthesis and corneocyte lipid envelope (CLE) formation involved in maintaining the epidermal barrier. Prompted by the recovery of a disrupted epidermal barrier with dietary borage oil (BO: 40.9% linoleic acid (LNA) and 24.0% γ-linolenic acid (GLA)) in essential fatty acid (EFA) deficiency, lipidomic and transcriptome analyses and subsequent quantitative RT-PCR were performed to determine the effects of borage oil (BO) on TAG content and species, and the gene expression related to overall lipid metabolism. Dietary BO for 2 weeks in EFA-deficient guinea pigs increased the total TAG content, including the TAG species esterified LNA, GLA, and their C20 metabolized fatty acids. Moreover, the expression levels of genes in the monoacylglycerol and glycerol-3-phosphate pathways, two major pathways of TAG synthesis, increased, along with those of TAG lipase, acyl-Cer synthesis, and CLE formation. Dietary BO enhanced TAG content, the gene expression of TAG metabolism, acyl-Cer synthesis, and CLE formation.
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Cossignani, L., D. Montesano, M. S. Simonetti, and F. Blasi. "Authentication ofCoffea arabicaaccording to Triacylglycerol Stereospecific Composition." Journal of Analytical Methods in Chemistry 2016 (2016): 1–7. http://dx.doi.org/10.1155/2016/7482620.
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Stereospecific analysis is an important tool for the characterization of lipid fraction of food products. In the present research, an approach to characterizearabicaandrobustavarieties by structural analysis of the triacylglycerol (TAG) fraction is reported. The lipids were Soxhlet extracted from ground roasted coffee beans with petroleum ether, and the fatty acids (FA) were determined as their corresponding methyl esters. The results of a chemical-enzymatic-chromatographic method were elaborated by a chemometric procedure, Linear Discriminant Analysis (LDA). According to the total and intrapositional FA composition of TAG fraction, the obtained results were able to characterize roasted pure coffee samples and coffee mixtures with 10%robustacoffee added toarabicacoffee. Totally correct classified samples were obtained when the TAG stereospecific results of the considered coffee mixture (90 : 10arabica/robusta) were elaborated by LDA procedure.
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Gunawan, Setiyo, and Yi Hsu Ju. "Pemisahan squalene dan fatty acid sterol esters dari soybean oil deodorizer distillate." Jurnal Teknik Kimia Indonesia 7, no. 2 (October 2, 2018): 780. http://dx.doi.org/10.5614/jtki.2008.7.2.3.
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Depending on conditions in the refining process, soybean oil deodorizer distillate (SODD) contains 42-51% free fatty acids (FFA) and 16-25% triacylglycerol (TAG). Bioactive compounds such as tocopherols, free phytosterols, fatty acid steryl esters (FASE) and squalene also make up a significant portion of SODD. The efficient removal of FFA and TAG is a crucial step in the isolation and purification of bioactive compounds from SODD. In this work, a modified soxhlet extraction technique was developed and its optimal operation conditions were determined for the efficient removal of FFA and TAG from SODD. Starting with SODD that contains 3.53% FASE and 1.99% squalene, it was possible to obtain a fraction enriched with FASE (22.0%, recovery 91.3%) and squalene (8.63%, recovery 100%) by this modified soxhlet extraction under the following operation conditions: SODD/(silica gel) = 1/3 (w/w), extraction temperature = -6°C, number of extraction/h = 8.7. FFA remained in this FASE and squalene enriched fraction is 38.7% and there was no detectable TAG. The percentage removal of FFA and TAG for this FASE and squalene enriched fraction are 84.29% and 100%, respectively. The advantages of modified soxhlet extraction over open-column chromatography are that less solvent usage, larger sample size per batch and shorter operation time.Keywords: Fatty acid steryl ester; free fatty acid; modified soxhlet extraction; soybean oil deodorizer distillate; squalene; triacylglycerol AbstrakDalam proses pemurnian minyak kedelai, produk samping dari proses penghilangan bau (soybean oil deodorizer distillate, SODD) mengandung 42-52% free fatty acids (FFA) dan 18-28% triacylglycerols (TAG). Komponen bioaktif seperti tocopherols, free phytosterols, fatty acid steryl esters (FASE) dan squalene juga mempunyai kontribusi yang besar dalam komposisi SODD. Efisiensi penghilangan FFA dan TAG adalah langkah yang sangat penting dalam pemisahan dan pemurnian komponen bioaktif dari SODD. Dalam penelitian ini, modifikasi soxhlet ekstraksi telah ditemukan dan optimisasi kondisi operasi ditentukan berdasarkan efisiensi penghilangan FFA dan TAG dari SODD. Fraksi lemak non polar (nonpolar lipid fraction, NPLF) dengan kandungan FASE (22.0%, recovery 91.3%) dan squalene (8.63%, recovery 100%) telah diperoleh dengan menggunakan modifikasi soxhlet ektraksi dengan kondisi operasi: SODD/(silica gel) = 1/3 (w/w), dan suhu ekstraksi = -6°C. FFA dan TAG yang tersisa di NPLF secara berurutan adalah 38.7% dan 0%. Persentase penghilangan FFA dan TAG di NPLF secara berurutan adalah 84.29% and 100%. Keuntungan menggunakan modifikasi soxhlet ekstraksi dibandingkan dengan silica gel column chromatography adalah sedikitnya pelarut yang digunakan, besarnya sampel per unit batch yang digunakan, dan pendeknya waktu operasi.Kata kunci: Free fatty acid, fatty acid steryl ester, modifikasi soxhlet ekstraksi, soybean oil deodorizer distillate, squalene, triacylglycerols
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Dauk, Melanie, Patricia Lam, and Mark A. Smith. "The role of diacylglycerol acyltransferase-1 and phospholipid:diacylglycerol acyltransferase-1 and -2 in the incorporation of hydroxy fatty acids into triacylglycerol in Arabidopsis thaliana expressing a castor bean oleate 12-hydroxylase geneThis paper is one of a selection of papers published in a Special Issue from the National Research Council of Canada – Plant Biotechnology Institute." Botany 87, no. 6 (June 2009): 552–60. http://dx.doi.org/10.1139/b09-011.
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Expression of oleate 12-hydroxylase genes in Arabidopsis results in the accumulation of hydroxy fatty acids in seed triacylglycerol (TAG). The pathways by which these unusual fatty acids become incorporated into TAG are not well understood. We expressed a fatty acid hydroxylase cDNA in Arabidopsis mutant lines to assess the role of three enzymes implicated in TAG assembly in this species. Plants deficient in the expression of phospholipid:diacylglycerol acyltransferase-1 or -2 accumulated hydroxy fatty acids and showed no differences to equivalent transformed wild-type plants. Plants lacking diacylglylcerol acyltransferase activity were also able to accumulate hydroxy fatty acids in seed neutral lipids. Triacylglycerol species containing one and two hydroxy fatty acids were abundant, and small amounts of trihydroxy-TAG were detected. These results indicate that individually, the three enzymes do not play a major role in the incorporation of hydroxy fatty acids into TAG.
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Arabolaza, Ana, Eduardo Rodriguez, Silvia Altabe, Hector Alvarez, and Hugo Gramajo. "Multiple Pathways for Triacylglycerol Biosynthesis in Streptomyces coelicolor." Applied and Environmental Microbiology 74, no. 9 (February 29, 2008): 2573–82. http://dx.doi.org/10.1128/aem.02638-07.
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ABSTRACT The terminal reaction in triacylglyceride (TAG) biosynthesis is the esterification of diacylglycerol (DAG) with a fatty acid molecule. To study this reaction in Streptomyces coelicolor, we analyzed three candidate genes (sco0958, sco1280, and sco0123) whose products significantly resemble the recently identified wax ester synthase/acyl-coenzyme A (CoA):DAG acyltransferase (DGAT) from Acinetobacter baylyi. The deletion of either sco0123 or sco1280 resulted in no detectable decrease in TAG accumulation. In contrast, the deletion of sco0958 produced a dramatic reduction in neutral lipid production, whereas the overexpression of this gene yielded a significant increase in de novo TAG biosynthesis. In vitro activity assays showed that Sco0958 mediates the esterification of DAG using long-chain acyl-CoAs (C14 to C18) as acyl donors. The Km and V max values of this enzyme for myristoyl-CoA were 45 μM and 822 nmol mg−1 min−1, respectively. Significantly, the triple mutant strain was not completely devoid of storage lipids, indicating the existence of alternative TAG-biosynthetic routes. We present strong evidence demonstrating that the residual production of TAG in this mutant strain is mediated, at least in part, by an acyl-CoA-dependent pathway, since the triple mutant still exhibited DGAT activity. More importantly, there was substantial phospholipid:DGAT (PDAT) activity in the wild type and in the triple mutant. This is the first time that a PDAT activity has been reported for bacteria, highlighting the extreme metabolic diversity of this industrially important soil microorganism.
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Sauro, Victor S., and Kenneth P. Strickland. "Triacylglycerol synthesis and diacylglycerol acyltransferase activity during skeletal myogenesis." Biochemistry and Cell Biology 68, no. 12 (December 1, 1990): 1393–401. http://dx.doi.org/10.1139/o90-202.
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The role that diacylglycerol acyltransferase (DAGAT) may play in the switch in lipid metabolism from predominantly triacylglycerol- and phospholipid-synthesizing myoblasts to predominantly phospholipid-synthesizing myotubes has been studied during L6 skeletal myogenesis. Fatty acid induced triacylglycerol (TAG) accumulation in vivo was found to be optimal with long-chain, unsaturated fatty acids. The fatty acid induced TAG accumulation was significantly greater in myoblasts than that in myotubes. DAGAT activity in vitro was found to be associated with the particulate (membrane) fraction only. The inhibition by many thiol-specific reagents (N-ethylmaleimide, p-chloromercuribenzoate, iodoacetate, 5,5′-dithiobis(2-nitrobenzoic acid)) suggest that a thiol group is at or near the active site. In general, optimal DAGAT activity in vitro was observed when long-chain unsaturated acyl-CoAs and diacylglycerols (DAGs) containing long acyl chains were used as substrates for in vitro TAG synthesis (although 1,2-didecanoin was also very effective). DAGAT activity (expressed relative to DNA) was shown to decline over twofold during skeletal myogenesis when measured in the absence of exogenous DAG. However, in the presence of exogenous (1 mM) DAG, there was no significant change in DAGAT activity, suggesting that the levels of this enzyme are not altered during skeletal myogenesis. These results indicate that endogenous DAG levels are limiting TAG synthesis in L6 myotubes. However, DAG content of myotubes was significantly greater than that of myoblasts, suggesting that there may be an increased competition for DAG (perhaps owing to enhanced phospholipid synthesis) during skeletal myogenesis. The combined effects of decreased synthesis and increased degradation (reported earlier) of TAG may account for the decrease in endogenous TAG contents observed during skeletal myogenesis.Key words: diacylglycerol acyltransferase, TAG synthesis, skeletal myogenesis.
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Gimenez-Llort, L., J. Vilanova, N. Skottova, G. Bengtsson-Olivecrona, M. Llobera, and M. Q. Robert. "Lipoprotein lipase enables triacylglycerol hydrolysis by perfused newborn rat liver." American Journal of Physiology-Gastrointestinal and Liver Physiology 261, no. 4 (October 1, 1991): G641—G647. http://dx.doi.org/10.1152/ajpgi.1991.261.4.g641.
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Fasted 1-day-old rat liver has high heparin-releasable (endothelial) lipoprotein lipase (LPL) activity, and its hepatocytes synthesize LPL protein. To test the physiological role of this LPL, we perfused the isolated organ with a 0.8 mM triacylglycerol (TAG) (Intralipid + glycerol tri[3H]oleate) 6.3% serum medium. Samples of the recirculated perfusate were taken at different times to determine 3H in TAG, free fatty acid (FFA), and water-soluble (WS) fractions. In the medium [3H]TAG disappeared and [3H]FFA and [3H]WS fractions appeared linearly with time. This TAG hydrolysis was 1) absent when medium was recirculated without liver, 2) not affected by chloroquine addition, 3) inhibited by anti-LPL immunoglobulins, 4) absent when serum was omitted from the medium, and 5) restituted when apolipoprotein CII was added to the medium without serum. Therefore, lysosomal lipase is not involved in this TAG hydrolysis, the features of which are characteristic of LPL, not of the so-called "hepatic endothelial lipase." Thus LPL activity enables the neonatal rat liver to hydrolyze and take up circulating TAG, i.e., has the same function as extrahepatic LPL.
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Perona, Javier S., María P. Portillo, M. Teresa Macarulla, Ana I. Tueros, and Valentina Ruiz-Gutiérrez. "Influence of different dietary fats on triacylglycerol deposition in rat adipose tissue." British Journal of Nutrition 84, no. 5 (November 2000): 756–74. http://dx.doi.org/10.1017/s0007114500002130.
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It has been demonstrated that triacylglycerol (TAG) mobilization from adipose tissue is selective and depends on fatty acid (FA) chain length, unsaturation and positional isomerism. The present study was performed to determine the influence of dietary fat on the composition of TAG stored in rat perirenal and subcutaneous adipose tissues. These results may provide information on the susceptibility of stored TAG to hydrolysis and further mobilization, and may help to establish an interrelationship between dietary composition and the FA efflux from adipose tissue. TAG molecular species and FA composition were determined by HPLC and GLC respectively. No significant differences were found in either FA or TAG composition between perirenal and subcutaneous adipose depots. The major FA in the dietary fats were present in the adipose tissues of the animals; in most cases, in similar proportions. However, differences were found between dietary and adipose tissue content of minor FA, which suggests that dietary FA composition is altered between ingestion and deposition in adipose tissue. The TAG molecular species of rat adipose tissue were enriched with the FA characteristic of each dietary fat. Dietary sunflower oil was responsible for enrichment with the most polar TAG. This finding may suggest easier mobilization of stored TAG. In conclusion, the process of fatty acid and TAG deposition in rat adipose tissue is selective, and depends on the composition of the diet.
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Potts, J. L., S. W. Coppack, R. M. Fisher, S. M. Humphreys, G. F. Gibbons, and K. N. Frayn. "Impaired postprandial clearance of triacylglycerol-rich lipoproteins in adipose tissue in obese subjects." American Journal of Physiology-Endocrinology and Metabolism 268, no. 4 (April 1, 1995): E588—E594. http://dx.doi.org/10.1152/ajpendo.1995.268.4.e588.
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Adipose tissue is an important site of clearance of circulating triacylglycerol (TAG), especially in the postprandial period. Postprandial lipemia is usually increased in obesity. We studied the extraction of TAG from plasma and TAG-rich lipoproteins (TRLs) in subcutaneous adipose tissue in 11 control and 8 obese subjects before and after a mixed meal. Clearance of plasma TAG and very low-density lipoprotein (VLDL)-TAG was decreased in the obese subjects after an overnight fast. After the meal, chylomicron-TAG extraction increased in the control group whereas VLDL-TAG clearance decreased; these changes were not seen in the obese group, in whom the VLDL particles appeared to be better able to compete with the chylomicrons for clearance by lipoprotein lipase. In the control subjects, removal of TAG from the TRL in the postprandial period was accompanied by a shift toward addition of cholesterol to the high-density lipoprotein (HDL) fraction; this was not observed in the obese subjects. We conclude that disturbed TRL-TAG clearance in adipose tissue is related both to the elevated plasma TAG concentrations and the depressed HDL-cholesterol concentrations typical of obesity.
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Bafor, M., L. Jonsson, A. K. Stobart, and S. Stymne. "Regulation of triacylglycerol biosynthesis in embryos and microsomal preparations from the developing seeds of Cuphea lanceolata." Biochemical Journal 272, no. 1 (November 15, 1990): 31–38. http://dx.doi.org/10.1042/bj2720031.
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Embryos of Cuphea lanceolata have more than 80 mol% of decanoic acid (‘capric acid’) in their triacylglycerols, while this fatty acid is virtually absent in phosphatidylcholine (PtdCho). Seed development was complete 25-27 days after pollination, with rapid triacylglycerol deposition occurring between 9 and 24 days. PtdCho amounts increased until day 15 after pollination. Analysis of embryo lipids showed that the diacylglycerol (DAG) pool consisted of mainly long-chain molecular species, with a very small amount of mixed medium-chain/long-chain glycerols. Almost 100% of the fatty acid at position sn-2 in triacylglycerols (TAG) was decanoic acid. When equimolar mixtures of [14C]decanoic and [14C]oleic acid were fed to whole detached embryos, over half of the radioactivity in the DAG resided in [14C]oleate, whereas [14C]decanoic acid accounted for 93% of the label in the TAG. Microsomal preparations from developing embryos at the mid-stage of TAG accumulation catalysed the acylation of [14C]glycerol 3-phosphate with either decanoyl-CoA or oleoyl-CoA, resulting in the formation of phosphatidic acid (PtdOH), DAG and TAG. Very little [14C]glycerol entered PtdCho. In combined incubations, with an equimolar supply of [14C]oleoyl-CoA and [14C]decanoyl-CoA in the presence of glycerol 3-phosphate, the synthesized PtdCho species consisted to 95% of didecanoic and dioleic species. The didecanoyl-glycerols were very selectively utilized over the dioleoylglycerols in the production of TAG. Substantial amounts of [14C]oleate, but not [14C]decanoate, entered PtdCho. The microsomal preparations of developing embryos were used to assess the acyl specificities of the acyl-CoA:sn-glycerol-3-phosphate acyltransferase (GPAT, EC 2.3.1.15) and the acyl-CoA:sn-1-acyl-glycerol-3-phosphate acyltransferase (LPAAT, EC 2.3.1.51) in Cuphea lanceolata embryos. The efficiency of acyl-CoA utilization by the GPAT was in the order decanoyl = dodecanoyl greater than linoleoyl greater than myristoyl = oleoyl greater than palmitoyl. Decanoyl-CoA was the only acyl donor to be utilized to any extent by the LPAAT when sn-decanoylglycerol 3-phosphate was the acyl acceptor. sn-1-Acylglycerol 3-phosphates with acyl groups shorter than 16 carbon atoms did not serve as acyl acceptors for long-chain (greater than or equal to 16 carbon atoms) acyl-CoA species. On the basis of the results obtained, we propose a schematic model for triacylglycerol assembly and PtdCho synthesis in a tissue specialized in the synthesis of high amounts of medium-chain fatty acids.
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Fraser, Angus J. "Triacylglycerol Content as a Condition Index for Fish, Bivalve, and Crustacean Larvae." Canadian Journal of Fisheries and Aquatic Sciences 46, no. 11 (November 1, 1989): 1868–73. http://dx.doi.org/10.1139/f89-235.
Full textAbstract:
The lipid biochemistry of environmentally stressed larval fish, bivalves and crustaceans is presented to illustrate the utility of a larval condition index based on lipid composition. Larvae under environmental stress are often unable to obtain sufficient energy from exogenous sources and, as a result, endogenous energy reserves are catabolised to maintain basal metabolism. The storage lipid triacylglycerol (TAG) is of particular importance in this respect, TAG content consequently correlating with the physiological condition of a larva. However, absolute TAG content cannot be directly correlated with larval condition because of its dependency on larval size. It is proposed that TAG content can be correlated with larval condition when expressed in the form of a TAG-sterol ratio that accounts for the size dependency of TAG content. This proposition is supported by data that illustrate a highly positive correlation between sterol content and dry weight for larval herring and larval American lobster. Examples of TAG-sterol ratios are calculated from a survey of studies relating to the lipid class composition of nutritionally and pollutant stressed larvae of some marine fish and crustaceans.
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SWANTON, M. S. Eleithyia, and E. David SAGGERSON. "Effects of adrenaline on triacylglycerol synthesis and turnover in ventricular myocytes from adult rats." Biochemical Journal 328, no. 3 (December 15, 1997): 913–22. http://dx.doi.org/10.1042/bj3280913.
Full textAbstract:
Ca2+-tolerant myocytes were isolated with endogenous triacylglycerol (TAG) stores prelabelled with [3H]palmitate and subsequently incubated for a 1 h chase period with [14C]palmitate, 2% albumin and 5 mM glucose. Measurements were then made of [14C]palmitate conversion into TAG and phospholipids, of loss of [3H]TAG, of glycerol release and of change in the total TAG content. Rates of de novo synthesis of TAG were calculated by a balance method. With 0.5 mM palmitate present, 5 μM adrenaline increased de novo synthesis of TAG by 81% and incorporation of [14C]palmitate into phospholipids by 59%. Significant increases in these processes with adrenaline were also seen with 0.08, 0.14 and 0.26 mM palmitate. The β-agonist isoprenaline had little effect on de novo synthesis of TAG and had no effect on [14C]palmitate conversion into phospholipids. The α1-agonist phenylephrine mimicked adrenaline in increasing [14C]palmitate conversion into phospholipids but had no effect on de novo synthesis of TAG. Adrenaline did not significantly alter the myocyte glycerol 3-phosphate content but caused a persistent 40% increase in the activity of the form of glycerolphosphate acyltransferase found predominantly in the sarcoplasmic reticulum. With 0.5 mM palmitate present, the value [14C]TAG formed -decrease in [3H]TAG consistently exceeded the enzymically measured change in cell TAG content. From this it was suggested that the specific radioactivity of [3H]TAG pool(s) mobilized during the chase period was lower than that of the overall cell TAG. In the basal state, complete mobilization of TAG measured as glycerol release was low, but cycling of TAG to diacylglycerol or monoacylglycerol and back to TAG appeared to be high. With adrenaline present, glycerol release was increased 5-6-fold but recycling of lower acylglycerols to TAG was abolished. Glycerol release was inhibited by increasing extracellular palmitate from 0.08 to 0.5 mM. Adrenaline partially over-rode this effect.
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Sun, Feifei, Mike Stolinski, Fariba Shojaee-Moradie, Shaoying Lou, Yuying Ma, Roman Hovorka, and A. Margot Umpleby. "A novel method for measuring intestinal and hepatic triacylglycerol kinetics." American Journal of Physiology-Endocrinology and Metabolism 305, no. 8 (October 15, 2013): E1041—E1047. http://dx.doi.org/10.1152/ajpendo.00105.2013.
Full textAbstract:
This study aimed to 1) develop a method that completely separated hepatic (VLDL1, VLDL2) and intestinal [chylomicron (CM)] lipoproteins and 2) use the method to measure triacylglycerol (TAG) kinetics in these lipoproteins in the fed and fasting state in healthy subjects, using intravenous [2H5]glycerol as the tracer. An immunoaffinity method that completely separated hepatic and intestinal particles using sequential binding to three antibodies to apolipoprotein B-100 (apoB-100) was established and validated. Six healthy volunteers were studied in a fasted and continuous feeding study ( study 1). Five additional healthy volunteers were studied in a continuous feeding study that included an oral [13C3]glycerol tripalmitin tracer ( study 2). In both studies, an intravenous bolus of [2H5]glycerol was administered to label TAG in hepatic and intestinal lipoproteins. In both feeding studies there was sufficient incorporation of the [2H5]glycerol tracer into the exogenous lipoproteins to enable isotopic enrichment to be measured. In study 2, the oral tracer enrichment in VLDL1 was <5% of CM enrichment 150 min after tracer administration, demonstrating negligible contamination of VLDL1 with apoB-48. Western blotting showed no detectable apoB-100 in CMs. VLDL1 and VLDL2 TAG fractional catabolic rate (FCR) did not differ between feeding and fasting ( study 1). There was no difference between CM and VLDL1 TAG FCR in both fed studies. In fed study 2, 47% of the total TAG production rate (CM + VLDL1) was from CM. This methodology may be a useful tool for understanding the abnormalities in postprandial TAG kinetics in metabolic syndrome and type 2 diabetes.
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HEBBACHI, Abdel-Malek, Marilia C. L. SEELAENDER, Paul W. BAKER, and Geoffrey F. GIBBONS. "Decreased secretion of very-low-density lipoprotein triacylglycerol and apolipoprotein B is associated with decreased intracellular triacylglycerol lipolysis in hepatocytes derived from rats fed orotic acid or n–3 fatty acids." Biochemical Journal 325, no. 3 (August 1, 1997): 711–19. http://dx.doi.org/10.1042/bj3250711.
Full textAbstract:
Hepatocytes from rats fed a chow (control) diet or from rats fed a chow diet supplemented with either orotic acid (OA; 1%, w/w) or fish oil (FO; 20%, v/w) were maintained in culture for periods up to 48 h. During the first 24 h period, the low rates of output of very-low-density lipoprotein (VLDL)-associated triacylglycerol (TAG) and apolipoprotein B (apoB) in hepatocytes from the FO- and OA-fed animals were associated with significantly lower rates of intracellular TAG lipolysis and re-esterification. Most of the VLDL TAG secreted was mobilized via lipolysis of the intracellular TAG pool, but the proportion of VLDL TAG secreted via this route in cells from the FO-fed and OA-fed animals was decreased compared with that in the control-fed animals' cells. In the presence of exogenous oleate the inhibitory effect of OA feeding on VLDL apoB and TAG secretion persisted in the derived hepatocytes for up to 48 h following isolation. However, when oleate was absent no inhibitory effect on the secretion of TAG and apoB was observed between 24 and 48 h. Under these conditions the rate of intracellular TAG turnover returned to normal. The initial inhibitory effect of FO feeding on VLDL TAG and apoB secretion did not persist in the derived hepatocytes between 24 h and 48 h of culture in the presence of exogenous oleate. Although intracellular TAG lipolysis and VLDL TAG and apoB secretion rates appear to be positively correlated, a causal relationship has not been conclusively established.
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Li, Xiaobo, Christoph Benning, and Min-Hao Kuo. "Rapid Triacylglycerol Turnover in Chlamydomonas reinhardtii Requires a Lipase with Broad Substrate Specificity." Eukaryotic Cell 11, no. 12 (October 5, 2012): 1451–62. http://dx.doi.org/10.1128/ec.00268-12.
Full textAbstract:
ABSTRACT When deprived of nitrogen (N), the photosynthetic microalga Chlamydomonas reinhardtii accumulates large quantities of triacylglycerols (TAGs), making it a promising source of biofuel. Prominent transcriptional changes associated with the conditions leading to TAG accumulation have been found, suggesting that the key enzymes for TAG metabolism might be among those that fluctuate in their expression during TAG synthesis and breakdown. Using a Saccharomyces cerevisiae lipase null mutant strain for functional complementation, we identified the CrLIP1 gene from Chlamydomonas based on its ability to suppress the lipase deficiency-related phenotypes of the yeast mutant. In Chlamydomonas , an inverse correlation was found between the CrLIP1 transcript level and TAG abundance when Chlamydomonas cultures were reversibly deprived of N. The CrLIP1 protein expressed and purified from Escherichia coli exhibited lipolytic activity against diacylglycerol (DAG) and polar lipids. The lipase domain of CrLIP1 is most similar to two human DAG lipases, DAGLα and DAGLβ. The involvement of CrLIP1 in Chlamydomonas TAG hydrolysis was corroborated by reducing the abundance of the CrLIP1 transcript with an artificial micro-RNA, which resulted in an apparent delay in TAG lipolysis when N was resupplied. Together, these data suggest that CrLIP1 facilitates TAG turnover in Chlamydomonas primarily by degrading the DAG presumably generated from TAG hydrolysis.
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Iizuka, Katsumi, Ken Takao, Takehiro Kato, Yukio Horikawa, and Jun Takeda. "ChREBP Reciprocally Regulates Liver and Plasma Triacylglycerol Levels in Different Manners." Nutrients 10, no. 11 (November 7, 2018): 1699. http://dx.doi.org/10.3390/nu10111699.
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Carbohydrate response element-binding protein (ChREBP) has an important role in the carbohydrate-mediated regulation of hepatic de novo lipogenesis, but the mechanism for how it regulates plasma triacylglycerol (TAG) levels has not been established. This study aimed to clarify the role of ChREBP in regulation of plasma TAG levels. We analyzed the metabolic changes in mice infected with an adenovirus expressing ChREBP Δ196 (Ad-ChREBP). Compared with adenovirus harboring green fluorescent protein infected mice, Ad-ChREBP-infected mice had higher plasma free fatty acid levels and paradoxically lower plasma 3-hydroxybutyrate levels through decreased fatty acid oxidation, rather than ketogenesis. Consistent with their hepatomegaly and increased lipogenic gene expression, the liver TAG contents were much higher. Regarding lipid composition, C16:0 was much lower and C18:1n-9 was much higher, compatible with increased stearoyl CoA desaturase-1 and ELOVL fatty acid elongase 6 expression. Furthermore, Ad-ChREBP-infected mice had decreased plasma TAG and very low density lipoprotein (VLDL)-TAG levels, consistent with decreased Angiopoietin-like protein 3 (Angptl3) and increased fibroblast growth factor (Fgf21) mRNA and protein levels. Finally, Ad-ChREBP infection increased white adipose tissue Ucp1 mRNA levels with increased plasma Fgf21 levels. Because Fgf21 and Angptl3 are known to activate and suppress lipolysis in adipose tissues and oxidative tissues, ChREBP appears to regulate plasma TAG levels by modulating Fgf21 and Angptl3 levels. Thus, ChREBP overexpression led to dissociation of hepatic steatosis from hyperlipidemia.
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Chamli, D., M. A. Bootello, I. Bouali, S. Jouhri, S. Boukhchina, and E. Martínez-Force. "Chemical characterization and thermal properties of kernel oils from Tunisian peach and nectarine varieties of Prunus persica." Grasas y Aceites 68, no. 3 (September 8, 2017): 211. http://dx.doi.org/10.3989/gya.0111171.
Full textAbstract:
A comparative study was conducted to determine the fatty acids, triacylglycerol compositions and thermal properties of Tunisian kernel oils from the Prunus persica varieties, peach and nectarine, grown in two areas of Tunisia, Gabes and Morneg. Qualitatively, the fatty acids composition and triacylglycerol species were identical for all samples. Oleic acid (67.7-75.0%) was the main fatty acid, followed by linoleic (15.7-22.1%) and palmitic (5.6-6.3%) acids. The major triacylglycerol species were triolein, OOO (38.4-50.5%), followed by OOL (18.2-23.2%), POO (8.3-9.7%) and OLL (6.3-10.1%). The thermal profiles were highly influenced by the high content of triolein due to the importance of oleic acid in these oils. Moreover, the fatty acids distribution in TAG external positions was determined as corresponding to an α asymmetry coefficient that was between 0.10 and 0.12, indicating a high asymmetry in the distribution of saturated fatty acids in the position sn-1 and sn-3 in the TAG species of all samples.
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Quinalha, Flávia Santina Pelissari, Luciana Pelissari Manin, Marina Masetto Antunes, Guilherme Godoy, Marília Bellanda Galuch, Eloize Silva Alves, Omar Cléo Neves Pereira, et al. "Influence of fatty acids composition in different tissue of mice feeds with fish oils." Research, Society and Development 10, no. 16 (December 13, 2021): e338101623706. http://dx.doi.org/10.33448/rsd-v10i16.23706.
Full textAbstract:
Omega-3 long-chain polyunsaturated fatty acids (n-3 LC-PUFA), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) play an important role in human health. Fish oils enriched with EPA and DHA have commercialized in triacylglycerol (TAG) and ethyl ester forms (EE). In this study, we compared the impact of diets containing fish oil in ethyl ester and triacylglycerol forms as a lipid source in five different tissues as liver, skeleteral muscle, brain, and epididymal white adipose tissue (WAT). The DHA levels were higher in the WAT and skeletal muscle of TAG and EE groups in comparison with the SB group. The body weight and brain, liver, epididymal WAT, and gastrocnemius muscle weights, and serum glucose, TG, cholesterol were not different between the groups. Thus, we conclude that EPA and DHA in the form of EE or TAG influence the fatty acids composition of different tissues.
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Sun, F., M. Stolinski, F. Shojaee-Moradie, and A. M. Umpleby. "Measurement of endogenous and exogenous triacylglycerol kinetics in the fed and fasted states." Biochemical Society Transactions 35, no. 3 (May 22, 2007): 482–83. http://dx.doi.org/10.1042/bst0350482.
Full textAbstract:
Emerging evidence has shown that an abnormal postprandial accumulation of dietary fat is atherogenic. However, there is a lack of data describing the mechanisms for accumulation of triacylglycerol (TAG) in the postprandial period. There is therefore a need to establish a specific measure of the kinetics of endogenous and exogenous TAG in the postprandial period.
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DOLINSKY, Vernon W., Donna N. DOUGLAS, Richard LEHNER, and Dennis E. VANCE. "Regulation of the enzymes of hepatic microsomal triacylglycerol lipolysis and re-esterification by the glucocorticoid dexamethasone." Biochemical Journal 378, no. 3 (March 15, 2004): 967–74. http://dx.doi.org/10.1042/bj20031320.
Full textAbstract:
Hepatic VLDL (very-low-density lipoprotein) assembly is a complex process that is largely regulated by the provision of lipid for apolipoprotein B assembly. Intracellular stored TAG (triacylglycerol) undergoes an initial lipolysis followed by re-esterification of the lipolytic products to form TAG prior to their incorporation into a VLDL particle. TGH (TAG hydrolase) is a lipase that hydrolyses intracellular TAG within the hepatocyte. We have utilized both dexamethasone-injected mouse and primary hepatocyte models to address whether stimulation of TAG biosynthesis by the synthetic glucocorticoid, dexamethasone, altered hepatic lipolysis and re-esterification and the provision of stored TAG for lipoprotein secretion. Dexamethasone treatment resulted in decreased TGH expression, primarily due to a dexamethasone-induced decrease in TGH mRNA stability. The expression and activities of diacylglycerol acyltransferases 1 and 2 were stimulated by dexamethasone. The combination of reduced intracellular TAG lipolysis and increased TAG biosynthesis contributed to the accumulation of TAG within the livers of dexamethasone-injected mice. The rate of hepatic TAG secretion in dexamethasonetreated mice was maintained at similar levels as in control mice. Our data demonstrate that stimulation of de novo TAG synthesis by dexamethasone increased the proportion of secreted TAG that was derived from de novo sources, while the utilization of stored TAG for secretion was reduced. The results show that, during markedly increased TAG synthesis, some TAGs are diverted from the cytosolic storage pool and are utilized directly for VLDL assembly within the endoplasmic reticulum lumen.
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Blasi, Francesca, Germana Lombardi, Pietro Damiani, Maria Stella Simonetti, Laura Giua, and Lina Cossignani. "Triacylglycerol stereospecific analysis and linear discriminant analysis for milk speciation." Journal of Dairy Research 80, no. 2 (November 28, 2012): 144–51. http://dx.doi.org/10.1017/s0022029912000635.
Full textAbstract:
Product authenticity is an important topic in dairy sector. Dairy products sold for public consumption must be accurately labelled in accordance with the contained milk species. Linear discriminant analysis (LDA), a common chemometric procedure, has been applied to fatty acid% composition to classify pure milk samples (cow, ewe, buffalo, donkey, goat). All original grouped cases were correctly classified, while 90% of cross-validated grouped cases were correctly classified. Another objective of this research was the characterisation of cow-ewe milk mixtures in order to reveal a common fraud in dairy field, that is the addition of cow to ewe milk. Stereospecific analysis of triacylglycerols (TAG), a method based on chemical–enzymatic procedures coupled with chromatographic techniques, has been carried out to detect fraudulent milk additions, in particular 1, 3, 5% cow milk added to ewe milk. When only TAG composition data were used for the elaboration, 75% of original grouped cases were correctly classified, while totally correct classified samples were obtained when both total and intrapositional TAG data were used. Also the results of cross validation were better when TAG stereospecific analysis data were considered as LDA variables. In particular, 100% of cross-validated grouped cases were obtained when 5% cow milk mixtures were considered.
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Steenson, Simon, Fariba Shojaee-Moradie, Martin B. Whyte, Kim G. Jackson, Julie A. Lovegrove, Barbara A. Fielding, and A. Margot Umpleby. "The Effect of Fructose Feeding on Intestinal Triacylglycerol Production and De Novo Fatty Acid Synthesis in Humans." Nutrients 12, no. 6 (June 15, 2020): 1781. http://dx.doi.org/10.3390/nu12061781.
Full textAbstract:
A high fructose intake exacerbates postprandial plasma triacylglycerol (TAG) concentration, an independent risk factor for cardiovascular disease, although it is unclear whether this is due to increased production or impaired clearance of triacylglycerol (TAG)-rich lipoproteins. We determined the in vivo acute effect of fructose on postprandial intestinal and hepatic lipoprotein TAG kinetics and de novo lipogenesis (DNL). Five overweight men were studied twice, 4 weeks apart. They consumed hourly mixed-nutrient drinks that were high-fructose (30% energy) or low-fructose (<2% energy) for 11 h. Oral 2H2O was administered to measure fasting and postprandial DNL. Postprandial chylomicron (CM)-TAG and very low-density lipoprotein (VLDL)-TAG kinetics were measured with an intravenous bolus of [2H5]-glycerol. CM and VLDL were separated by their apolipoprotein B content using antibodies. Plasma TAG (p < 0.005) and VLDL-TAG (p = 0.003) were greater, and CM-TAG production rate (PR, p = 0.046) and CM-TAG fractional catabolic rate (FCR, p = 0.073) lower when high-fructose was consumed, with no differences in VLDL-TAG kinetics. Insulin was lower (p = 0.005) and apoB48 (p = 0.039), apoB100 (p = 0.013) and non-esterified fatty acids (NEFA) (p = 0.013) were higher after high-fructose. Postprandial hepatic fractional DNL was higher than intestinal fractional DNL with high-fructose (p = 0.043) and low-fructose (p = 0.043). Fructose consumption had no effect on the rate of intestinal or hepatic DNL. We provide the first measurement of the rate of intestinal DNL in humans. Lower CM-TAG PR and CM-TAG FCR with high-fructose consumption suggests lower clearance of CM, rather than elevated production, may contribute to elevated plasma TAG, possibly due to lower insulin-mediated stimulation of lipoprotein lipase.
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Kaçar, S., M. Başhan, and S. A. Oymak. "Effect of season on the fatty acid profile of total lipids, phospholipids and triacylglycerols in Mastacembelus mastacembelus (Atatürk Dam Lake, Turkey)." Grasas y Aceites 69, no. 1 (March 22, 2018): 242. http://dx.doi.org/10.3989/gya.1108172.
Full textAbstract:
The present study investigated the lipid content and FA profiles of total lipids, phospholipids (PL) and triacylglycerols (TAG) of Mastacembelus mastacembelus from the Atatürk Dam Lake (Turkey). The results showed that the total lipid content of the dorsal muscle varied seasonally from 0.50% to 3.59%. Wide ranges of saturated fatty acids (SFAs) (36.21 to 50.52%) and polyunsaturated fatty acids (PUFAs) (25.22 to 42.02%) were found in the PL fraction. However, higher monounsaturated fatty acids (MUFAs) (37.63 to 45.07%) and SFA (34.71 to 38.82%) were found in TAG (triacylglycerol). The ratios of ω-3 to ω-6 PUFA ranged from 0.65 to 1.32 and 1.07 to 3.48 in PL (phospholipid) and TAG fraction, respectively.
The results also showed that the major components were palmitic acid (C16:0), stearic acid (C18:0), oleic acid (C18:1ω-9), palmitoleic acid (C16:1ω-7), docosahexaenoic acid (DHA, C22:6ω-3), arachidonic acid (AA, C20:4ω-6) and docosapentaenoic acid (C22:5ω-3) in total lipid, C16:0, C18:1ω-9, AA and DHA in PL, C16:0, C16:1ω-7, C18:1ω-9, linoleic acid (LA, C18:2ω-6), and DHA in TAG extracted from the muscle of M. mastacembelus in all seasons.
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WIGGINS, David, and Geoffrey F. GIBBONS. "Origin of hepatic very-low-density lipoprotein triacylglycerol: the contribution of cellular phospholipid." Biochemical Journal 320, no. 2 (December 1, 1996): 673–79. http://dx.doi.org/10.1042/bj3200673.
Full textAbstract:
When rat hepatocytes were cultured for 24 h in the absence of exogenous fatty acid, the amount of very-low-density lipoprotein (VLDL) triacylglycerol (TAG) secreted (114±14 µg/mg of cell protein) could not be accounted for by the mass of TAG lost from the cells (29±6.1 µg/mg of cell protein) during this period (n = 12). Of the balance (85±14 µg/mg; 94±15 nmol/mg), a maximum of only 37 nmol/mg of cell protein of TAG could be accounted for by fatty acids synthesized de novo. When labelled exogenous oleate (initial concentration, 0.75 mM) was present in the culture medium, the net gain in cellular plus VLDL TAG (253±38 µg/mg of cell protein per 24 h) was greater than that contributed by the exogenous fatty acid (155±18.2 µg/mg of cell protein, n = 5). Again, the balance (98.8±18.2 µg/mg of cell protein per 24 h) was too great to be accounted for by fatty acid synthesis de novo. In experiments in which cellular glycerolipids were prelabelled with [9,10(n)-3H]oleic acid, following removal of the labelled fatty acid, there was a net increase in labelled cellular plus VLDL TAG over the next 24 h. That cellular phospholipids are the source of a substantial part of the excess TAG synthesized is supported by the following evidence. (1) The loss of prelabelled cellular phospholipid during culture was greater than could be accounted for by secretion into the medium. (2) During culture of cells prelabelled with 1,2-di-[1-14C]palmitoyl phosphatidylcholine, a substantial amount of label was secreted as VLDL TAG. (3) In pulse–chase experiments, the kinetics of labelled phospholipid turnover were consistent with conversion into a non-phospholipid pool. The enzymology involved in the transfer of phospholipid fatty acids into TAG is probably complex, but the present results suggest that this pathway may represent an important route by which extracellular fatty acids are channelled into VLDL TAG.
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Shi, Yuguang, and Dong Cheng. "Beyond triglyceride synthesis: the dynamic functional roles of MGAT and DGAT enzymes in energy metabolism." American Journal of Physiology-Endocrinology and Metabolism 297, no. 1 (July 2009): E10—E18. http://dx.doi.org/10.1152/ajpendo.90949.2008.
Full textAbstract:
Monoacyglycerol acyltransferases (MGATs) and diacylglycerol acyltransferases (DGATs) catalyze two consecutive steps of enzyme reactions in the synthesis of triacylglycerols (TAGs). The metabolic complexity of TAG synthesis is reflected by the presence of multiple isoforms of MGAT and DGAT enzymes that differ in catalytic properties, subcellular localization, tissue distribution, and physiological functions. MGAT and DGAT enzymes play fundamental roles in the metabolism of monoacylglycerol (MAG), diacylglycerol (DAG), and triacylglycerol (TAG) that are involved in many aspects of physiological functions, such as intestinal fat absorption, lipoprotein assembly, adipose tissue formation, signal transduction, satiety, and lactation. The recent progress in the phenotypic characterization of mice deficient in MGAT and DGAT enzymes and the development of chemical inhibitors have revealed important roles of these enzymes in the regulation of energy homeostasis and insulin sensitivity. Consequently, selective inhibition of MGAT or DGAT enzymes by synthetic compounds may provide novel treatment for obesity and its related metabolic complications.
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Watt, Matthew J., and Gregory R. Steinberg. "Regulation and function of triacylglycerol lipases in cellular metabolism." Biochemical Journal 414, no. 3 (August 27, 2008): 313–25. http://dx.doi.org/10.1042/bj20080305.
Full textAbstract:
The ability to store energy in the form of energy-dense TAG (triacylglycerol) and to mobilize these stores rapidly during times of low carbohydrate availability (fasting or famine) or during heightened metabolic demand (exercise or cold-stress) is a highly conserved process essential for survival. Today, in the presence of nutrient excess and sedentary lifestyles, the regulation of this pathway is viewed as an important therapeutic target for disease prevention, as elevated circulating fatty acids in obesity contribute to many aspects of the metabolic syndrome including hepatic steatosis, atherosclerosis and insulin resistance. In the present review, we discuss the metabolic regulation and function of TAG lipases with a focus on HSL (hormone-sensitive lipase), ATGL (adipose triacylglycerol lipase) and newly identified members of the lipolytic proteome.
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Ren, Cuirong, Jun Jin, Thom Huppertz, Yanbing Zhang, Qingzhe Jin, and Xingguo Wang. "Evaluation of Fatty Acid Distributions and Triacylglycerol Species in Sow Milk and Commercial Piglet Formulas: A Comparative Study Based on Fat Sources and Lactation Stages." Animals 13, no. 1 (December 28, 2022): 124. http://dx.doi.org/10.3390/ani13010124.
Full textAbstract:
Total fatty acid and sn-2 fatty acid compositions, and triacylglycerol (TAG) species in 130 sow colostrum, 100 sow milk, and 22 piglet formula samples were analyzed in the present study. Significant differences were found in concentrations of medium chain-saturated fatty acids (MC-SFAs) and distributions of palmitic acid (P) and oleic (O)/linoleic (L) acid. The levels of MC-SFAs in sow colostrum and sow milk fats (2.4–3.1%) were significantly lower than those in piglet formulas (7.9–27.2%). Approximately 63% of palmitic acid was located at the sn-2 position in both sow colostrum and milk fats, which was significantly higher than in piglet formula fats (21.1–39.1%). Correspondingly, only 17.8–28.3% of oleic and linoleic acids were at the sn-2 position in sow milk fats, contributing to their typical triacylglycerol structure in sow colostrum and milk, whose palmitic acid connected to the sn-2 position and unsaturated fatty acids located at the sn-1,3 positions. Sow colostrum, milk, and piglet formulas were notably distinguished into three groups based on their fatty acids and TAGs, among which triacylglycerols were the most differentiated index. A total of 51 TAG species (including their isomers) differed significantly between sow colostrum and milk and piglet formulas. OPL and OPO were the most important differentiating TAGs. The large amount of sn-2 esterified palmitic acid plays a key role in improving the absorption of fat and calcium. The results provide suggestions for design of sow milk fat equivalents.
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Wong, Annette T. Y., Dick C. Chan, Esther M. M. Ooi, Theodore W. K. Ng, Gerald F. Watts, and P. Hugh R. Barrett. "Omega-3 fatty acid ethyl ester supplementation decreases very-low-density lipoprotein triacylglycerol secretion in obese men." Clinical Science 125, no. 1 (March 13, 2013): 45–51. http://dx.doi.org/10.1042/cs20120587.
Full textAbstract:
Dysregulated VLDL-TAG (very-low-density lipoprotein triacylglycerol) metabolism in obesity may account for hypertriacylglycerolaemia and increased cardiovascular disease. ω-3 FAEEs (omega-3 fatty acid ethyl esters) decrease plasma TAG and VLDL concentrations, but the mechanisms are not fully understood. In the present study, we carried out a 6-week randomized, placebo-controlled study to examine the effect of high-dose ω-3 FAEE supplementation (3.2 g/day) on the metabolism of VLDL-TAG in obese men using intravenous administration of d5-glycerol. We also explored the relationship of VLDL-TAG kinetics with the metabolism of VLDL-apo (apolipoprotein) B-100 and HDL (high-density lipoprotein)-apoA-I. VLDL-TAG isotopic enrichment was measured using gas chromatography-mass spectrometry. Kinetic parameters were derived using a multicompartmental model. Compared with placebo, ω-3 FAEE supplementation significantly lowered plasma concentrations of total (−14%, P<0.05) and VLDL-TAG (−32%, P<0.05), as well as hepatic secretion of VLDL-TAG (−32%, P<0.03). The FCR (fractional catabolic rate) of VLDL-TAG was not altered by ω-3 FAEEs. There was a significant association between the change in secretion rates of VLDL-TAG and VLDL-apoB-100 (r=0.706, P<0.05). However, the change in VLDL-TAG secretion rate was not associated with change in HDL-apoA-I FCR (r=0.139, P>0.05). Our results suggest that the TAG-lowering effect of ω-3 FAEEs is associated with the decreased VLDL-TAG secretion rate and hence lower plasma VLDL-TAG concentration in obesity. The changes in VLDL-TAG and apoB-100 kinetics are closely coupled.
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Berry, Sarah E. E., and Thomas A. B. Sanders. "Influence of triacylglycerol structure of stearic acid-rich fats on postprandial lipaemia." Proceedings of the Nutrition Society 64, no. 2 (May 2005): 205–12. http://dx.doi.org/10.1079/pns2005422.
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Exaggerated postprandial lipaemia may increase the risk of CHD by contributing to both thrombotic and atherogenic processes. Previous research has focused on the quantity and composition of dietary fat, whereas the effect of triacylglycerol (TAG) structure on postprandial lipaemia and clotting factor VII activity has received little attention. TAG with similar fatty acid composition may have different biochemical and physical properties that are dependent on their TAG structure, and these differences may affect lipid metabolism. Recent findings suggest that differences in the physical properties of stearic acid-rich fats are associated with differences in postprandial lipaemia, and may play an important role in determining their rates of digestion and absorption.
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Kim, Yeongho, Ee Leng Terng, Wayne R. Riekhof, Edgar B. Cahoon, and Heriberto Cerutti. "Endoplasmic reticulum acyltransferase with prokaryotic substrate preference contributes to triacylglycerol assembly in Chlamydomonas." Proceedings of the National Academy of Sciences 115, no. 7 (January 30, 2018): 1652–57. http://dx.doi.org/10.1073/pnas.1715922115.
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Understanding the unique features of triacylglycerol (TAG) metabolism in microalgae may be necessary to realize the full potential of these organisms for biofuel and biomaterial production. In the unicellular green alga Chlamydomonas reinhardtii a chloroplastic (prokaryotic) pathway has been proposed to play a major role in TAG precursor biosynthesis. However, as reported here, C. reinhardtii contains a chlorophyte-specific lysophosphatidic acid acyltransferase, CrLPAAT2, that localizes to endoplasmic reticulum (ER) membranes. Unlike canonical, ER-located LPAATs, CrLPAAT2 prefers palmitoyl-CoA over oleoyl-CoA as the acyl donor substrate. RNA-mediated suppression of CrLPAAT2 indicated that the enzyme is required for TAG accumulation under nitrogen deprivation. Our findings suggest that Chlamydomonas has a distinct glycerolipid assembly pathway that relies on CrLPAAT2 to generate prokaryotic-like TAG precursors in the ER.
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Romano, Adele, Marzia Friuli, Laura Del Coco, Serena Longo, Daniele Vergara, Piero Del Boccio, Silvia Valentinuzzi, et al. "Chronic Oleoylethanolamide Treatment Decreases Hepatic Triacylglycerol Level in Rat Liver by a PPARγ/SREBP-Mediated Suppression of Fatty Acid and Triacylglycerol Synthesis." Nutrients 13, no. 2 (January 27, 2021): 394. http://dx.doi.org/10.3390/nu13020394.
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Oleoylethanolamide (OEA) is a naturally occurring bioactive lipid belonging to the family of N-acylethanolamides. A variety of beneficial effects have been attributed to OEA, although the greater interest is due to its potential role in the treatment of obesity, fatty liver, and eating-related disorders. To better clarify the mechanism of the antiadipogenic effect of OEA in the liver, using a lipidomic study performed by 1H-NMR, LC-MS/MS and thin-layer chromatography analyses we evaluated the whole lipid composition of rat liver, following a two-week daily treatment of OEA (10 mg kg−1 i.p.). We found that OEA induced a significant reduction in hepatic triacylglycerol (TAG) content and significant changes in sphingolipid composition and ceramidase activity. We associated the antiadipogenic effect of OEA to decreased activity and expression of key enzymes involved in fatty acid and TAG syntheses, such as acetyl-CoA carboxylase, fatty acid synthase, diacylglycerol acyltransferase, and stearoyl-CoA desaturase 1. Moreover, we found that both SREBP-1 and PPARγ protein expression were significantly reduced in the liver of OEA-treated rats. Our findings add significant and important insights into the molecular mechanism of OEA on hepatic adipogenesis, and suggest a possible link between the OEA-induced changes in sphingolipid metabolism and suppression of hepatic TAG level.
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MacEachran, Daniel P., M. E. Prophete, and A. J. Sinskey. "The Rhodococcus opacus PD630 Heparin-Binding Hemagglutinin Homolog TadA Mediates Lipid Body Formation." Applied and Environmental Microbiology 76, no. 21 (September 17, 2010): 7217–25. http://dx.doi.org/10.1128/aem.00985-10.
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ABSTRACT Generally, prokaryotes store carbon as polyhydroxyalkanoate, starch, or glycogen. The Gram-positive actinomycete Rhodococcus opacus strain PD630 is noteworthy in that it stores carbon in the form of triacylglycerol (TAG). Several studies have demonstrated that R. opacus PD630 can accumulate up to 76% of its cell dry weight as TAG when grown under nitrogen-limiting conditions. While this process is well studied, the underlying molecular and biochemical mechanisms leading to TAG biosynthesis and subsequent storage are poorly understood. We designed a high-throughput genetic screening to identify genes and their products required for TAG biosynthesis and storage in R. opacus PD630. We identified a gene predicted to encode a putative heparin-binding hemagglutinin homolog, which we have termed tadA (triacylglycerol accumulation deficient), as being important for TAG accumulation. Kinetic studies of TAG accumulation in both the wild-type (WT) and mutant strains demonstrated that the tadA mutant accumulates 30 to 40% less TAG than the parental strain (WT). We observed that lipid bodies formed by the mutant strain were of a different size and shape than those of the WT. Characterization of TadA demonstrated that the protein is capable of binding heparin and of agglutinating purified lipid bodies. Finally, we observed that the TadA protein localizes to lipid bodies in R. opacus PD630 both in vivo and in vitro. Based on these data, we hypothesize that the TadA protein acts to aggregate small lipid bodies, found in cells during early stages of lipid storage, into larger lipid bodies and thus plays a key role in lipid body maturation in R. opacus PD630.
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Deeba, Farha, Ruchir Priyadarshi, Vikas Pruthi, and Yuvraj Singh Negi. "Activating de novo triacylglycerol synthesis in oleaginous yeast for improved bio-diesel quality." WEENTECH Proceedings in Energy 4, no. 2 (November 16, 2018): 16–24. http://dx.doi.org/10.32438/wpe.8218.
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The economic production of yeast biofuels requires several strategies, such as multiomics techniques to gain insights into lipid biosynthesis pathway. Hence, metabolomic studies for amelioration of triacylglycerol (TAG) accumulation in oleaginous yeast strain to reveal potential targets in fatty acid synthesis pathway should be explored. The aim of this research experiment was to boost TAG agglomeration in novel isolated oleaginous yeast Cryptococcus psychrotolerans IITRFD using sodium bicarbonate as supplement for biodiesel production. Enhanced biomass productivity (83.5 ± 0.32 mg/L/h) and lipid productivity (56.8 ± 0.34 mg/L/h) have been estimated as compared to yeast nitrogen base media (YNB) used as control. Also, the bicarbonate supplementation (25 mM) leads to decrease in phospholipids (23.6 %) while increase in TAG amount (75.4 %) signifying that it redirects the phospholipids synthesis pathway in the direction of de novo TAG pathway. The fatty acid profile obtained revealed rise in monounsaturated fatty acid content and decrease in polyunsaturated fatty acid content demonstrating better oxidative stability (19 h) and cold flow behaviour (- 12 °C) of biodiesel produced. This novel strategy of utilizing bicarbonate as a triggering system may possibly revamp the commercial use of C. psychrotolerans IITRFD for high quality biodiesel production. This is the first study to augment TAG accumulation in this oleaginous yeast using sodium bicarbonate with improved fuel properties.
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Zhou, Jun, Yee-Ying Lee, Yilin Mao, Yong Wang, and Zhen Zhang. "Future of Structured Lipids: Enzymatic Synthesis and Their New Applications in Food Systems." Foods 11, no. 16 (August 10, 2022): 2400. http://dx.doi.org/10.3390/foods11162400.
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Structured lipids (SLs) refer to a new type of functional lipid obtained by modifying natural triacylglycerol (TAG) through the restructuring of fatty acids, thereby altering the composition, structure, and distribution of fatty acids attached to the glycerol backbones. Due to the unique functional characteristics of SLs (easy to absorb, low in calories, reduced serum TAG, etc.), there is increasing interest in the research and application of SLs. SLs were initially prepared using chemical methods. With the wide application of enzymes in industries and the advantages of enzymatic synthesis (mild reaction conditions, high catalytic efficiency, environmental friendliness, etc.), synthesis of SLs using lipase has aroused great interest. This review summarizes the reaction system of SL production and introduces the enzymatic synthesis and application of some of the latest SLs discussed/developed in recent years, including medium- to long-chain triacylglycerol (MLCT), diacylglycerol (DAG), EPA- and DHA-enriched TAG, human milk fat substitutes, and esterified propoxylated glycerol (EPG). Lastly, several new ways of applying SLs (powdered oil, DAG plastic fat, inert gas spray oil, and emulsion) in the future food industry are also highlighted.
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O’Donnell, J. Michael, Manuela Zampino, Nathaniel M. Alpert, Matthew J. Fasano, David L. Geenen, and E. Douglas Lewandowski. "Accelerated triacylglycerol turnover kinetics in hearts of diabetic rats include evidence for compartmented lipid storage." American Journal of Physiology-Endocrinology and Metabolism 290, no. 3 (March 2006): E448—E455. http://dx.doi.org/10.1152/ajpendo.00139.2005.
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Triacylglycerol (TAG) storage and turnover rates in the intact, beating rat heart were determined for the first time using dynamic mode 13C- NMR spectroscopy to elucidate profound differences between hearts from diabetic rats (DR, streptozotocin treatment) and normal rats (NR). The incorporation of [2,4,6,8,10,12,14,16-13C8]palmitate into the TAG pool was monitored in isolated hearts perfused with physiological (0.5 mM palmitate, 5 mM glucose) and elevated substrate levels (1.2 mM palmitate, 11 mM glucose) characteristic of the diabetic condition. Surprisingly, although the normal hearts were enriched at a near-linear profile for ≥2 h before exponential characterization, exponential enrichment of TAG in diabetic hearts reached steady state after only 45 min. Consequently, TAG turnover rate was determined by fitting an exponential model to enrichment data rather than conventional two-point linear analysis. In the high-substrate group, both turnover rate (DR 820 ± 330, NR 190 ± 150 nmol·min−1·g−1 dry wt; P < 0.001) and [TAG] content (DR 78 ± 10, NR 32 ± 4 μmol/g dry wt; P < 0.001) were greater in the diabetic group. At lower substrate concentrations, turnover was greater in diabetics (DR 530 ± 300, NR 160 ± 30; P < 0.05). However, this could not be explained by simple mass action, because [TAG] content was similar between groups [DR 34 ± 7, NR 39 ± 9 μmol/g dry wt; not significant (NS)]. Consistent with exponential enrichment data, 13C fractional enrichment of TAG was lower in diabetics (low- substrate groups: DR 4 ± 1%, NR 10 ± 4%, P < 0.05; high-substrate groups: DR 8 ± 3%, NR 14 ± 9%, NS), thereby supporting earlier speculation that TAG is compartmentalized in the diabetic heart.
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Picklo, Matthew, Michael Bukowski, Bastien Vallée Marcotte, Frédéric Guénard, and Marie-Claude Vohl. "Lipidomic Assessment of Triacylglycerol and Cholesterol Ester Species After n-3 Polyunsaturated Fatty Acid Suppementation in Humans: Comparison of Response Phenotypes." Current Developments in Nutrition 4, Supplement_2 (May 29, 2020): 450. http://dx.doi.org/10.1093/cdn/nzaa045_083.
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Abstract Objectives Assess the differences in triacylglycerol (TAG) and cholesterol ester (CE) species in the plasma of individuals displaying heterogeneous lipid responses following long chain n-3 (LCn-3) polyunsaturated fatty acid supplementation. Methods We performed a targeted, mass spectrometry (MS), infusion-based lipidomic analysis on plasma samples obtained from a clinical study in which participants were supplemented with 3 g/day of LCn-3 in the form of fish oil capsules over a 6-week period. Triacylglycerol (TAG) species and cholesteryl esters (CE) were quantified for 130 participants pre- and post-supplementation. Results Based on the change of total TAG concentrations following supplementation, participants were segregated into three response phenotypes: (1) positive responders (R+; TAG decrease < 10%), (2) non-responders (NR; TAG changes +/− 10%), and (3) negative responders (R−; TAG increase > 10%) representing 87/130 (67%), 24/130 (18%), and 19/130 (15%) of the study samples, respectively. There were no phenotypic differences for age, sex, body-mass index, glycemia, or ApoB concentrations. Sparse partial least squares discriminant analysis separated the three phenotypes with component 1 attributed to changes in TAG 50–53: X with 0–3 desaturations with R + having reductions in these TAG. Separation along component 2 identified lower mass TAG 46–48: X with 1–3 desaturations likely containing 14:0. This latter effect impacted mostly NR and R- phenotypes. Analysis of individual TAG species per response phenotype revealed TAG species that did not align with the overall TAG response phenotype. Using the TAG response phenotype for grouping, we performed SPLDA analysis for CE responses. We observed that distinction of the TAG response phenotypes qualitatively applies to CE in which separation along component 1 (65% of variance) was due to differences in CE 18:0, 18:1, and 14:0. CE 20:5 was elevated equally (>300%) between all phenotypes indicating LCn-3 intake. However, CE 22:6 was elevated R− (86%) to a greater extent vs. Res+ (55%) and NR (49%) phenotypes. Conclusions Our data identify lipidomic signatures (TAG and CE) associated with LCn-3 response phenotypes in humans and provide insight into the variability of lipid metabolism in humans. Funding Sources USDA-NIFA, USDA-ARS and CIHR MOP-229,488.
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Adler-Wailes, Diane C., Evan L. Guiney, Nathan E. Wolins, and Jack A. Yanovski. "Long-Term Ritonavir Exposure Increases Fatty Acid and Glycerol Recycling in 3T3-L1 Adipocytes as Compensatory Mechanisms for Increased Triacylglycerol Hydrolysis." Endocrinology 151, no. 5 (March 12, 2010): 2097–105. http://dx.doi.org/10.1210/en.2009-1364.
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Lipodystrophy with high nonesterified fatty acid (FA) efflux is reported in humans receiving highly active antiretroviral therapy (HAART) to treat HIV infection. Ritonavir, a common component of HAART, alters adipocyte FA efflux, but the mechanism for this effect is not established. To investigate ritonavir-induced changes in FA flux and recycling through acylglycerols, we exposed differentiated murine 3T3-L1 adipocytes to ritonavir for 14 d. FA efflux, uptake, and incorporation into acylglycerols were measured. To identify a mediator of FA efflux, we measured adipocyte triacylglycerol lipase (ATGL) transcript and protein. To determine whether ritonavir-treated adipocytes increased glycerol backbone synthesis for FA reesterification, we measured labeled glycerol and pyruvate incorporation into triacylglycerol (TAG). Ritonavir-treated cells had increased FA efflux, uptake, and incorporation into TAG (all P < 0.01). Ritonavir increased FA efflux without consistently increasing glycerol release or changing TAG mass, suggesting increased partial TAG hydrolysis. Ritonavir-treated adipocytes expressed significantly more ATGL mRNA (P < 0.05) and protein (P < 0.05). Ritonavir increased glycerol (P < 0.01) but not pyruvate (P = 0.41), utilization for TAG backbone synthesis. Consistent with this substrate utilization, glycerol kinase transcript (required for glycerol incorporation into TAG backbone) was up-regulated (P < 0.01), whereas phosphoenolpyruvate carboxykinase transcript (required for pyruvate utilization) was down-regulated (P < 0.001). In 3T3-L1 adipocytes, long-term ritonavir exposure perturbs FA metabolism by increasing ATGL-mediated partial TAG hydrolysis, thus increasing FA efflux, and leads to compensatory increases in FA reesterification with glycerol and acylglycerols. These changes in FA metabolism may, in part, explain the increased FA efflux observed in ritonavir-associated lipodystrophy.
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Yang, Tzu-Ling, Cheng-Liang Huang, and Chu-Ping Lee. "Utilizing AgNPt-SALDI to Classify Edible Oils by Multivariate Statistics of Triacylglycerol Profile." Molecules 26, no. 19 (September 28, 2021): 5880. http://dx.doi.org/10.3390/molecules26195880.
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Edible oils are valuable sources of nutrients, and their classification is necessary to ensure high quality, which is essential to food safety. This study reports the establishment of a rapid and straightforward SALDI-TOF MS platform used to detect triacylglycerol (TAG) in various edible oils. Silver nanoplates (AgNPts) were used to optimize the SALDI samples for high sensitivity and reproducibility of TAG signals. TAG fingerprints were combined with multivariate statistics to identify the critical features of edible oil discrimination. Eleven various edible oils were discriminated using principal component analysis (PCA). The results suggested the creation of a robust platform that can examine food adulteration and food fraud, potentially ensuring high-quality foods and agricultural products.
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Calligaris, Guilherme, Ana Paula Ribeiro, Adenilson dos Santos, and Lisandro Cardoso. "Rietveld Method Applied for Triacylglycerol Polymorphism Analysis." Acta Crystallographica Section A Foundations and Advances 70, a1 (August 5, 2014): C1764. http://dx.doi.org/10.1107/s2053273314082357.
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The characterization of the fat components becomes very useful in the formulation of shortening, margarines and fatty products due to their unique properties of plasticity, texture, solubility and aeration. The qualitative analysis obtained by X-ray diffraction (XRD) can be further improved in order to fulfill the lack of information on the triacylglycerol (TAG) in the hardfat systems aiming a complete polymorph characterization. In this work, as an attempt to quantify the distinct β and β' TAG polymorphs, XRD was combined with Rietveld refinement method and applied to two types of samples: mixtures (M) and blended hardfats (B) samples involving fully hydrogenated of soybean (FHSO) and palm (FHPO) oils. M-samples were prepared with linear concentrations of FHSO (β) and FHPO (β') and their Rietveld analysis have provided the expected content trend through the involved polymorphic phases with a very good agreement (~5%). This result validates the Rietveld method applicability on this kind of materials. The Rietveld method applied for B-samples has shown that β' polymorphic form prevails over the β-form, even for samples originally prepared with FHSO (β)/FHPO (β') = 60/40 ratio (see figure). This result indicates the influence of the seeding process (earlier crystallization of β' phase). This first quantitative approach for blended samples represents a very useful contribution towards the full characterization of fats.
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Brejchova, Kristyna, Franz Peter Walter Radner, Laurence Balas, Veronika Paluchova, Tomas Cajka, Hana Chodounska, Eva Kudova, et al. "Distinct roles of adipose triglyceride lipase and hormone-sensitive lipase in the catabolism of triacylglycerol estolides." Proceedings of the National Academy of Sciences 118, no. 2 (December 28, 2020): e2020999118. http://dx.doi.org/10.1073/pnas.2020999118.
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Branched esters of palmitic acid and hydroxy stearic acid are antiinflammatory and antidiabetic lipokines that belong to a family of fatty acid (FA) esters of hydroxy fatty acids (HFAs) called FAHFAs. FAHFAs themselves belong to oligomeric FA esters, known as estolides. Glycerol-bound FAHFAs in triacylglycerols (TAGs), named TAG estolides, serve as metabolite reservoir of FAHFAs mobilized by lipases upon demand. Here, we characterized the involvement of two major metabolic lipases, adipose triglyceride lipase (ATGL) and hormone-sensitive lipase (HSL), in TAG estolide and FAHFA degradation. We synthesized a library of 20 TAG estolide isomers with FAHFAs varying in branching position, chain length, saturation grade, and position on the glycerol backbone and developed an in silico mass spectra library of all predicted catabolic intermediates. We found that ATGL alone or coactivated by comparative gene identification-58 efficiently liberated FAHFAs from TAG estolides with a preference for more compact substrates where the estolide branching point is located near the glycerol ester bond. ATGL was further involved in transesterification and remodeling reactions leading to the formation of TAG estolides with alternative acyl compositions. HSL represented a much more potent estolide bond hydrolase for both TAG estolides and free FAHFAs. FAHFA and TAG estolide accumulation in white adipose tissue of mice lacking HSL argued for a functional role of HSL in estolide catabolism in vivo. Our data show that ATGL and HSL participate in the metabolism of estolides and TAG estolides in distinct manners and are likely to affect the lipokine function of FAHFAs.
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Lee, Hong Gil, Mid-Eum Park, Bo Yeon Park, Hyun Uk Kim, and Pil Joon Seo. "The Arabidopsis MYB96 Transcription Factor Mediates ABA-Dependent Triacylglycerol Accumulation in Vegetative Tissues under Drought Stress Conditions." Plants 8, no. 9 (August 22, 2019): 296. http://dx.doi.org/10.3390/plants8090296.
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Triacylglycerols (TAGs), a major lipid form of energy storage, are involved in a variety of plant developmental processes. While carbon reserves mainly accumulate in seeds, significant amounts of TAG have also been observed in vegetative tissues. Notably, the accumulation of leaf TAGs is influenced by environmental stresses such as drought stress, although underlying molecular networks remain to be fully elucidated. In this study, we demonstrate that the R2R3-type MYB96 transcription factor promotes TAG biosynthesis in Arabidopsis thaliana seedlings. Core TAG biosynthetic genes were up-regulated in myb96-ox seedlings, but down-regulated in myb96-deficient seedlings. In particular, ABA stimulates TAG accumulation in the vegetative tissues, and MYB96 plays a fundamental role in this process. Considering that TAG accumulation contributes to plant tolerance to drought stress, MYB96-dependent TAG biosynthesis not only triggers plant adaptive responses but also optimizes energy metabolism to ensure plant fitness under unfavorable environmental conditions.
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Takeguchi, Seiya, Arisa Sato, Hironori Hondoh, Mio Aoki, Hidetaka Uehara, and Satoru Ueno. "Multiple β Forms of Saturated Monoacid Triacylglycerol Crystals." Molecules 25, no. 21 (November 2, 2020): 5086. http://dx.doi.org/10.3390/molecules25215086.
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We have investigated the polymorphism of triacylglycerol (TAG) crystals as they affect the qualities such as shelf life, mouth feel, and texture of chocolate and other products. Saturated monoacid TAGs, like trilaurin, are considered as models for TAG crystallization; however, there is still debate about the number of their polymorphs that exist. In this study, we characterized a set of novel polymorphs, β forms of saturated monoacid TAGs, which were obtained via different pathways depending on the crystallization history, by polarized light microscopy, X-ray diffraction, and differential scanning calorimetry. Saturated monoacid TAGs were crystallized as the unstable polymorphs, the α or β’ forms first, and then they were transformed into β forms by solid–solid transformations. The β form that had transformed from β’ changed its morphology by a polymorphic transformation, while the β form made from the α form kept its spherulite morphology. The β forms obtained showed different melting points. Additional heat treatment promoted further polymorphic transformation. Four novel β forms were found for each of the saturated monoacid TAGs, trilaurin, trimyristin, tripalmitin, and tristearin. They showed similar polymorphism with the same subcell packing.