Fatty Acid Profiles Of Triacylglycerols Research Articles

Effect of starvation and pesticide exposure on neutral lipid composition of the digestive gland of males of the apple snails Pomacea canaliculata

Pollutants as well as starvation usually modify homeostasis of neutral lipids in aquatic organisms. However, studies on the simultaneous effects of both stressors are scarce. The aim of this study was to evaluate the effect of toxicant exposure under starvation conditions on neutral lipids of the freshwater snail Pomacea canaliculata, selected as the model organism. Starved adult male snails were exposed to sublethal concentration of the pesticide cypermethrin (100 µg/L) during 4 and 10 days. Fed snails were sacrificed at the onset of the experiment (T0), along with starved snails exposed to the pesticide vehicle (ethanol) and another group without solvent served as controls. Total lipid content, neutral lipid classes, fatty acid composition, and pesticide accumulation were determined in the digestive gland of snails. The ethanol concentration used was not an additional stressful agent. As expected, starvation caused a decrease in neutral lipid content in the digestive gland of snails with respect to T0 snails. Pesticide exposure caused, on the other hand, an increase in triacylglycerol content compared to ethanol exposure at day 10 of the bioassay. This increment correlated with the bioconcentration of cypermethrin, which was 47% higher by day 10 than by day 4. The fatty acid profile of triacylglycerols in the digestive gland was significantly altered under starvation and pesticide exposure. Stressed male snails showed the ability to preserve polyunsaturated fatty acids, as evidenced by their significant increase with respect to T0 snails. These results suggest that the alteration of lipid homeostasis could be involved in an adaptive mechanism of aquatic organisms to lipophilic and obesogenic pollutants.

Triacyl Glycerols from Yeast-Catalyzed Batch and Fed-Batch Bioconversion of Hydrolyzed Lignocellulose from Cardoon Stalks

The lipogenic ability of the yeast Solicoccozyma terricola DBVPG 5870 grown on hydrolyzed lignocellulose obtained from cardoon stalks was evaluated. Data on cell biomass, lipid production, and fatty acid profiles of triacylglycerols obtained in batch and fed-batch experiments were carried out at the laboratory scale in a 5L fermenter, and at two different temperatures (20 and 25 °C) were reported. The higher production of total intracellular lipids (13.81 g/L) was found in the fed-batch experiments carried out at 20 °C. S. terricola exhibited the ability to produce high amounts of triacylglycerol (TAGs) with a characteristic fatty acids profile close to that of palm oil. The TAGs obtained from S. terricola grown on pre-treated lignocellulose could be proposed as a supplementary source of oleochemicals. Indeed, due to the rising prices of fossil fuels and because of the environmental-related issues linked to their employment, the use of TAGs produced by S. terricola grown on lignocellulose could represent a promising option as a supplementary oleochemical, especially for biodiesel production.

Fatty Acid Profiles of Triacylglycerols and Phospholipids of Sea-Cage Cultured Trachinotus blochii: A Comparative Study of Head, Viscera, Skin, Bone, and Muscle.

Trachinotus blochii (golden pompano) is an economically important cultured marine fish that is rich in polyunsaturated fat. The fatty acid profiles of triacylglycerols and phospholipids of T. blochii tissues were analyzed. Lipid contents in tissues followed the order of viscera (28.27%) > skin (17.25%) ≈ bone (16.18%) ≈ head (15.12%) > muscle (7.38%). In triacylglycerols (TAG), saturated fatty acids (palmitic acid predominated) were preferentially esterified in the sn-2 position, and monounsaturated fatty acids (oleic acid predominated) were mainly distributed in the sn-1, 3 positions. The numbers of n-3 polyunsaturated fatty acids (PUFA) in the sn-2 position were significantly greater than those in positions 1 and 3, while the n-6 PUFA were mainly found in the sn-1, 3 positions. Muscle TAG had a higher content of EPA+DHA (3.90%) than did the other tissues. In phosphatidylethanolamines, EPA+DHA in muscle (6.76%) predominated over that in other tissues. In phosphatidylcholines, EPA+DHA in bone (6.50%) predominated. This study is a guide for the biochemical and nutritional values of the T. blochii species and can be useful for further investigation of industrial applications. PRACTICAL APPLICATION: The high proportion of sn-2-palmitic acid (greater than 50%) is close to that of breast milk and the n-3 PUFA, especially EPA and DHA have the preferential distribution in the sn-2 position of triacylglycerol. Hence, golden pompano is an excellent dietary component for human nutrition and health.

Differential effects of low-fat and high-fat diets on fed-state hepatic triacylglycerol secretion, hepatic fatty acid profiles, and DGAT-1 protein expression in obese-prone Sprague–Dawley rats

The purpose of this study was to compare the effects of short-term low-fat (LF) and high-fat (HF) diets on fed-state hepatic triacylglycerol (TAG) secretion, the content of proteins involved in TAG assembly and secretion, fatty acid oxidation (FAO), and the fatty acid profile of stored TAG. Using selectively bred obese-prone Sprague-Dawley rats, we directly measured fed-state hepatic TAG secretion, using Tyloxapol (a lipoprotein lipase inhibitor) and a standardized oral mixed meal (45% carbohydrate, 40% fat, 15% protein) bolus in animals fed a HF or LF diet for 2 weeks, after which the rats were maintained on their respective diet for 1 week (washout) prior to the liver being excised to measure protein content, FAO, and TAG fatty acid profiles. Hepatic DGAT-1 protein expression was ∼27% lower in HF- than in LF-fed animals (p < 0.05); the protein expression of all other molecules was similar in the 2 diets. The fed-state hepatic TAG secretion rate was ∼39% lower (p < 0.05) in HF- (4.62 ± 0.18 mmol·h(-1)) than in LF- (7.60 ± 0.57 mmol·h(-1)) fed animals. Hepatic TAG content was ∼2-fold higher (p < 0.05) in HF- (1.07 ± 0.15 nmol·g(-1) tissue) than in LF- (0.50 ± 0.16 nmol·g(-1) tissue) fed animals. In addition, the fatty acid profile of liver TAG in HF-fed animals closely resembled the diet, whereas in LF-fed animals, the fatty acid profile consisted of mostly de novo synthesized fatty acids. FAO was not altered by diet. LF and HF diets differentially alter fed-state hepatic TAG secretion, hepatic fatty acid profiles, and DGAT-1 protein expression.

Expression of a type 2 diacylglycerol acyltransferase from Thalassiosira pseudonana in yeast leads to incorporation of docosahexaenoic acid β‐oxidation intermediates into triacylglycerol

Glycerolipids of the marine diatom Thalassiosira pseudonana are enriched particularly with eicosapentaenoic acid (EPA), and also with an appreciable level of docosahexaenoic acid (DHA). The present study describes the functional characterization of a type 2 diacylglycerol acyltransferase (DGAT2, EC 2.3.1.20) from T. pseudonana, designated TpDGAT2, which catalyzes the final step of triacylglycerol (TAG) synthesis. Heterologous expression of this gene restored TAG formation in a yeast mutant devoid of TAG biosynthesis. TpDGAT2 was also shown to exert a large impact on the fatty acid profile of TAG. Its expression caused a 10-12% increase of 18:1 and a concomitant decrease of 16:0 relative to that of AtDGAT1(Arabidopsis thaliana). Furthermore, in the presence of the very-long-chain polyunsaturated fatty acids (VLCPUFA) EPA and DHA, TAG formed by TpDGAT2 displayed three- to six-fold increases in the percentage of VLCPUFA relative to that of AtDGAT1 even though TpDGAT2 conferred much lower TAG-synthetic activities than Arabidopsis DGAT1. Strikingly, when fed DHA, the yeast mutant expressing TpDGAT2 incorporated high levels of EPA and DHA isomers derived from DHA β-oxidation. In contrast, no such phenomenon occurred in the cells expressing AtDGAT1. These results suggested that, in addition to the role in breaking down storage lipids, yeast peroxisomes also contribute to lipid synthesis by recycling acyl-CoAs when a fatty acyl assembly system is available to capture and utilize the fatty acyl pools generated via β-oxidation. Our study hence illustrated a case where the efficiency and substrate preference of an acyltransferase can elicit far reaching metabolic adjustments that affect TAG composition.

Embryo-specific expression of soybean oleosin altered oil body morphogenesis and increased lipid content in transgenic rice seeds

Oleosin is the most abundant protein in the oil bodies of plant seeds, playing an important role in regulating oil body formation and lipid accumulation. To investigate whether lipid accumulation in transgenic rice seeds depends on the expression level of oleosin, we introduced two soybean oleosin genes encoding 24kDa proteins into rice under the control of an embryo-specific rice promoter REG-2. Overexpression of soybean oleosin in transgenic rice leads to an increase of seed lipid content up to 36.93 and 46.06% higher than that of the non-transgenic control, respectively, while the overall fatty acid profiles of triacylglycerols remained unchanged. The overexpression of soybean oleosin in transgenic rice seeds resulted in more numerous and smaller oil bodies compared with wild type, suggesting that an inverse relationship exists between oil body size and the total oleosin level. The increase in lipid content is accompanied by a reduction in the accumulation of total seed protein. Our results suggest that it is possible to increase rice seed oil content for food use and for use as a low-cost feedstock for biodiesel by overexpressing oleosin in rice seeds.

Effect of exercise training on the fatty acid composition of lipid classes in rat liver, skeletal muscle, and adipose tissue

The aim of the present study was to examine the effects of 8 weeks of exercise training on the fatty acid composition of phospholipids (PL) and triacylglycerols (TG) in rat liver, skeletal muscle (gastrocnemius medialis), and adipose tissue (epididymal and subcutaneous fat). For this purpose, the relevant tissues of 11 trained rats were compared to those of 14 untrained ones. Training caused several significant differences of large effect size in the concentrations and percentages of individual fatty acids in the aforementioned lipid classes. The fatty acid composition of liver PL, in terms of both concentrations and percentages, changed with training. The TG content of muscle and subcutaneous adipose tissue decreased significantly with training. In contrast to the liver, where no significant differences in the fatty acid profile of TG were found, muscle underwent more significant differences in TG than PL, and adipose tissue only in TG. Most differences were in the same direction in muscle and adipose tissue TG, suggesting a common underlying mechanism. Estimated fatty acid elongase activity was significantly higher, whereas Delta(9)-desaturase activity was significantly lower in muscle and adipose tissue of the trained rats. In conclusion, exercise training modified the fatty acid composition of liver PL, muscle PL and TG, as well as adipose tissue TG. These findings may aid in delineating the effects of exercise on biological functions such as membrane properties, cell signaling, and gene expression.

Effect of chronic wheel running on the fatty acid composition of phospholipids and triacylglycerols in rat serum, skeletal muscle and heart.

The purpose of this study was to examine the effects of long-term wheel running on the fatty acid composition of phospholipids (PL) and triacylglycerols (TG) in rat serum, skeletal muscle (soleus and extensor digitorum longus) and heart. To this end, the relevant tissues of 11 trained male Wistar rats were compared with those of 14 untrained ones. There were several significant differences between the two groups regarding the concentrations and percentages of individual fatty acids in serum PL and TG, with most differences appearing in the fatty acid distribution of PL. Monounsaturated fatty acids of muscle PL were significantly lower in the trained rats. Estimated elongase activity was significantly higher, whereas Delta(9)-desaturase activity was significantly lower in the trained muscles. Monounsaturated fatty acids of PL were also significantly lower in the trained hearts. The fatty acid composition of PL in the skeletal muscles and the heart adapted to training in a comparable manner, whereas most of the changes in the fatty acid profile of TG were tissue-dependent. Judging from the magnitude of the effect sizes and the percentage differences between trained and untrained animals, there were many large effects of chronic exercise on the fatty acid composition of the tissues examined. Long-term wheel running modified the fatty acid profile of PL and TG in rat serum, skeletal muscle and heart, and could thus be considered as a modulator of tissue fatty acid composition.

Variation in the content of tocopherols and distribution of fatty acids within soya bean seeds ( Glycine max L.)

Regional distribution of tocopherols and fatty acids within three soya beans was investigated by high-performance liquid chromatography and gas–liquid chromatography, respectively. Tocopherols were predominantly detected in axis, followed by cotyledons and seed coat. Dominant components were γ- and δ-tocopherols, with much smaller amounts of α- and β-tocopherols. However, α-tocopherol was higher ( P<0.05) in axis than other tissues. Triacylglycerols (TAGs) were the major component of total lipids, representing 92.0% in cotyledons and 70.0% in axis or coat. A small difference ( P<0.05) occurred in fatty acid profile of TAGs when comparing seed coat to the axis. The fatty acid composition of phosphatidyl inositol differed ( P<0.05) from phosphatidyl ethanolamine and phosphatidyl choline in each tissue. These results indicate that the differences in soya bean cultivars would be appreciable, based on the distribution of tocopherols and fatty acids in each component part within soya bean seeds.

Effects of Harvesting Time on Triacylglycerols and Glycerophospholipids of Sea Buckthorn (Hippophaë rhamnoides L.) Berries of Different Origins

Sea buckthorn (Hippophaë rhamnoides L.) berries of four cultivars of subsp.rhamnoides and two origins of wild subsp. sinensis were collected and analyzed in four consecutive years. The annual variations in fatty acid composition of seeds and berries within the origins were small. None of the four years showed any significant effect on either the absolute contents or the fatty acid profiles of triacylglycerols in seeds and whole berries, whereas significant differences were found among the different origins. From the end of August to the end of November, 1998, the contents of triacylglycerols and glycerophospholipids in berries of the two subsp. sinensis origins reached a maximum around the end of September. During this harvesting period, the fatty acid composition in seeds was constant, whereas that in the whole berries varied to a greater extent. The results suggested that compared with harvesting years, the time of the berry picking within a single year and the origins in question had more pronounced effects on the content and composition of triacylglycerols in berries of sea buckthorn. For the two origins (Wenshui and Xixian) of subsp. sinensis, the end of September seems to be the best harvesting time for a high yield of triacylglycerols and glycerophospholipids from the whole berries.