Stereospecific analysis of triacylglycerol and phospholipid fractions of five wild freshwater fish from Poyang Lake

Improvement in Muscle Fatty Acid Bioavailability and Volatile Flavor in Tilapia by Dietary α-Linolenic Acid Nutrition Strategy

To investigate the modification of muscle quality of farmed tilapia through dietary fatty acid strategies, two diets were formulated. Diet SO, using soybean oil as the lipid source, and diet BO, using blended soybean and linseed oils, each including 0.58% and 1.35% α-linolenic acid (ALA), respectively, were formulated to feed juvenile tilapia for 10 weeks. The muscular nutrition composition, positional distribution of fatty acid in triglycerides (TAGs) and phospholipids (PLs), volatile flavor, lipid mobilization and oxidation were then analyzed. The results showed that there was no distinct difference between the SO and BO groups in terms of the nutrition composition, including crude protein, crude lipid, TAGs, PLs, and amino acid. Although the fatty acid distribution characteristics in ATGs and PLs showed a similar trend in the two groups, a higher level of n-3 PUFA (polyunsaturated fatty acid) and n-3 LC-PUFA (long-chain polyunsaturated fatty acid) bound to the glycerol backbone of TAGs and PLs was detected in the BO group than the SO group, whereas the opposite was true for n-6 PUFA. Additionally, the muscular volatile aldehyde and alcohol levels were higher in the BO group. Moreover, the expression of enzymatic genes and protein activities related to lipid mobilization (LPL, LPCAT, DGAT) and oxidation (LOX and GPX) was higher in the BO group. The results demonstrate that high-ALA diets may improve the fatty acid bioavailability and volatile flavor of tilapia by improving the lipid mobilization and oxidation, which provides new ideas for the improvement of muscle quality in farmed fish.

Lipid-Mediated Mechanisms of Thermal Adaptation and Thermoregulatory Behavior in Animals

Temperature affects a variety of cellular processes because the molecular motion of cellular constituents and the rate of biochemical reactions are sensitive to temperature changes. Thus, the adaptation to temperature is necessary to maintain cellular functions during temperature fluctuation, particularly in poikilothermic organisms. For a wide range of organisms, cellular lipid molecules play a pivotal role during thermal adaptation. Temperature changes affect the physicochemical properties of lipid molecules, resulting in the alteration of cell membrane-related functions and energy metabolism. Since the chemical structures of lipid molecules determine their physicochemical properties and cellular functions, cellular lipids, particularly fatty acid-containing lipid molecules, are remodeled as a thermal adaptation response to compensate for the effects of temperature change. In this chapter, we first introduce the structure and biosynthetic pathway of fatty acid-containing lipid molecules, such as phospholipid and triacylglycerol, followed by a description of the cellular lipid-mediated mechanisms of thermal adaptation and thermoregulatory behavior in animals.

Tilapia nilotica Head Lipids Improved Bone Loss by Regulating Inflammation and Serum Metabolism Through Gut Microbiota in Ovariectomized Rats

Osteoporosis is a global health problem, and it is of great significance to replace the drugs with natural functional factors. In this study, we investigated the antiosteoporotic activity of lipids prepared from Tilapia nilotica fish head lipids (THLs) in the ovariectomized osteoporosis rats. THLs are composed of neutral lipids (NL, 77.84%), phospholipids (PL, 11.86%), and glycolipids (GL, 6.47%). There were apparent differences in the fatty acid composition of disparate components, and PL contains the most abundant Ω-3 polyunsaturated fatty acids. The results proved that THLs could improve bone microstructure, increase bone mineral density, and decrease bone resorption. To illustrate the antiosteoporotic mechanism, we analyzed the changes in gut microbial communities, proinflammation factors, serum metabolites, and metabolic pathways. Further study on gut microbiota showed that THLs significantly decreased the content of Alistipes in the gut and dramatically increased the beneficial bacteria such as Oscillospira, Roseburia, and Dubosiella. Meanwhile, proinflammation factors of serum in OVX rats decreased significantly, and metabolites were changed. Therefore, we speculated that THLs improved bone loss through reducing inflammation and changing the metabolites and metabolic pathways such as arachidonic acid metabolism and primary bile acid metabolism, etc., by altering gut microbiota. The results indicated that THLs could be a functional factor with antiosteoporotic activity.

Regio-distribution and double bond locations of unsaturated fatty acids in phospholipids of bovine milk

Hundreds of phospholipid (PL) species with defined fatty acid (FA) composition have been identified previously in bovine milk using liquid chromatography tandem mass spectrometry (LC-MS/MS). Paterno-Buchi photochemical reaction coupled with LC-MS/MS was applied in this study to further unravel the regio-distribution and double bond (DB) locations of FAs. Using SPE-purified PLs and 2-acetylpyridine as the photochemical derivatization reagent, we were able to reveal the non-specific regio-distribution of unsaturated FAs and the widespread occurrence of regioisomers in milk PLs. Although Δ9 and Δ9,12 were found to be the predominant DB location(s) for C18:1 and C18:2 respectively, other DB positional isomers such as C18:1Δ11, C18:1Δ12 and C18:1Δ13 and C18:2Δ9,11 were widely detected in PL structures, implying that the minor isomers of C18:1 and C18:2 equally participate in the synthesis of PLs. Our study provides novel information on the fine structure of milk PLs and further underlines the complexity of milk lipid composition.

Advances in exogenous docosahexaenoic acid-containing phospholipids: Sources, positional isomerism, biological activities, and advantages

In recent years, docosahexaenoic acid-containing phospholipids (DHA-PLs) have attracted much attention because of theirs unique health benefits. Compared with other forms of docosahexaenoic acid (DHA), DHA-PLs possess superior biological effects (e.g., anticancer, lipid metabolism regulation, visual development, and brain and nervous system biochemical reactions), more intricate metabolism mechanisms, and a stronger attraction to consumer. The production of DHA-PLs is hampered by several challenges associated with the limited content of DHA-PLs in natural sources, incomplete utilization of by-products, few microorganisms for DHA-PLs production, high cost, and complex process of artificial preparation of DHA-PLs. In this article, the sources, biological activities, and commercial applications of DHA-PLs were summarized, with intensive discussions on advantages of DHA-PLs over DHA, isomerism of DHA in phospholipids (PLs), and brain health. The excellent biological characteristics of DHA-PLs are primarily concerned with DHA and PLs. The metabolic fate of different DHA-PLs varies from the position of DHA in PLs to polar groups in DHA-PLs. Overall, well understanding of DHA-PLs about their sources and characteristics is critical to accelerate the production of DHA-PLs, economically enhance the value of DHA-PLs, and improve the applicability of DHA-PLs and the acceptance of consumers.

Inflammation and cardiovascular disease: are marine phospholipids the answer?

This review presents the latest research on the cardioprotective effects of n-3 fatty acids (FA) and n-3 FA bound to polar lipids (PL). Overall, n-3 PL may have enhanced bioavailability and potentially bioactivityversusfree FA and ester forms of n-3 FA.

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.

Fatty acid positional distribution in colostrum and mature milk of women living in Inner Mongolia, North Jiangsu and Guangxi of China

In order to investigate the fatty acid composition and distribution in colostrum and mature milk, breast milk samples and 24 h food records were obtained from 65 lactating women across three regions in China (Inner Mongolia, North Jiangsu and Guangxi). Fatty acid methyl esters were prepared by standard methods and separated and identified by gas chromatography. Compared with the Chinese breast milk fatty acid data 10 years ago, SFA and trans fatty acids (TFA) in breast milk decreased, while PUFA increased in the present study. Most SFA (C16:0, C15:0, C14:0), cis-C16:1 and several LC-PUFA (C22:5n-3 and C22:6n-3) were predominantly acylated at the sn-2 position. The cis-C17:1 and C22:6n-3 were distributed equally in three positions of triacylglycerol (TAG). Whereas, TFA, conjugated linoleic acids (CLA), cis-C18:1, C18:2n-6, C18:3n-3 and C20:5n-3 were acylated at the sn-1, 3 positions of TAG in human milk. The composition of fatty acids in breast milk was closely related to the diet of lactating mothers. PUFA in breast milk was negatively correlated with the intake of protein, fat and meat, but positively correlated with the intake of carbohydrates. MUFA of human milk was negatively correlated with the intake of dairy products, eggs, fish and shrimp. SFA in breast milk was positively correlated with the maternal intake of meat. In addition, the present results showed that the composition of total fatty acids and sn-2 fatty acids in breast milk varied with the lactation period and the geographical regions in China; however, the regiospecific fatty acid profile seemed not to be affected by the lactation time and regions, although the quantities at each position could be changed.

Effects of Chinese Dietary Pattern of Fat Content, n-6/n-3 Polyunsaturated Fatty Acid Ratio, and Cholesterol Content on Lipid Profile in Rats

This study aims to investigate the effect of Chinese diet pattern of fat content (30% or 36.06%), n-6/n-3 polyunsaturated fatty acid (PUFA) ratio (5 : 1 or 9 : 1), and cholesterol content (0.04 or 0.057 g/kg total diet) on lipid profile using a rat model. Results showed that rats' body weights (BWs) were controlled by the simultaneous intakes of cholesterol level of 0.04 g/kg total diet and n-6/n-3 ratio of 5 : 1. In addition, under high-fat diet, increased cholesterol feeding led to increased total cholesterol (TC) and low density lipoprotein cholesterol (LDL-C) levels and decreased triacylglycerols (TG) in rats' plasma. However, high density lipoprotein cholesterol (HDL-C) level and the ratios of HDL-C/LDL-C and HDL-C/TC in rats' plasma increased in response to simultaneous intakes of low n-6/n-3 ratio (5 : 1) and cholesterol (0.04 g/kg total diet) even under high-fat diet. Moreover, as the n-6/n-3 PUFA ratio in the diet decreased, the proportion of n-3 PUFAs increased in plasma, liver, and muscle and resulted in the decrease of n-6/n-3 PUFA ratio.

Regiospecific Analysis of Fatty Acids and Calculation of Triglyceride Molecular Species in Marine Fish Oils

The regiospecific distribution of fatty acids (FAs) and composition of triglyceride (TAG) molecular species of fishes were analyzed and calculated by pancreatic lipase (PL) hydrolysis and Visual Basic (VB) program. DHA was preferentially located at sn-2 position in TAG molecule, whereas EPA was almost equally distributed in each position of glycerol backbone. DOP, DPP, EPP, PoPP, PPO, and PPP were the predominant TAG species. MPP in anchovy, DDP, DOP, DPP in tuna, and EOO and OOO in salmon were the characteristic TAG molecules, which were meaningful to differentiate marine fish oils. Furthermore, the data management, according to TCN and ECN, was firstly applied to classify the TAG molecular species. The ECN42, ECN46, and ECN48 groups were rich in TAGs. The lower ECN values, compared to the higher TCN values, indicated that the most abundant TAGs exhibited a higher unsaturated degree. Therefore, our study not only offered a simple and feasible approach for the analysis of TAG composition but also firstly summarized the information by data management within ECN and TCN.

Triolein and trilinolein ameliorate oxidized low-density lipoprotein-induced oxidative stress in endothelial cells

Uptake of oxidized low-density lipoprotein by endothelial cells is a critical step for the initiation of atherosclerosis. Triacylglycerol uptake in these cells is understood to be a part of the process. The present investigation, comparison among the effects of simple acylglycerol, including tristearin, triolein, and trilinolein, upon oxidized low-density lipoprotein -induced oxidative stress was undertaken. Results indicated that trilinolein (78 % ± 0.02) and triolein (90 % ± 0.01) increased cell viability of endothelial cells exposed to oxidized low-density lipoprotein, whereas tristearin decreased the cell viability (55 % ± 0.03) (P < 0.05). Oxidized low-density lipoprotein treatment significantly increased apoptosis (23 %), compared to cells simultaneously exposed to trilinolein (19 %) or triolein (16 %), where apoptosis was reduced (P < 0.05). On the other hand, exposure to tristearin further increased oxidized low-density lipoprotein -induced cell apoptosis (34 %). Treatment with trilinolein or triolein on oxidized low-density lipoprotein -stimulated endothelial cells inhibited the expression of ICAM-1 and E-selectin mRNA. Moreover, both trilinolein and triolein demonstrated a strong antioxidant response to oxidative stress caused by oxidized low-density lipoprotein. Taken together, the results indicate trilinolein and triolein possess anti-inflammatory properties, which are mediated via the antioxidant defense system.

Two-dimensional ³¹P,¹H NMR spectroscopic profiling of phospholipids in cheese and fish

Phospholipids (PLs) comprise an important lipid class in food because of their technological use as emulsifiers and their nutritional value. This study used one-dimensional (31)P NMR and two-dimensional (2D) (31)P,(1)H COSY NMR spectroscopy for the determination of the PL composition of cheese and fish after liquid-liquid enrichment. This extraction step enabled the identification of 10 PLs in cheese and 9 PLs in fish by 2D (31)P,(1)H NMR. Variations in the (31)P shifts indicated differences in the fatty acids attached to the individual PLs. The total PL content in cheese fat and fish oil ranged from 0.3 to 0.4% and from 5 to 12%, respectively. Phosphatidylcholine was the most prominent PL in both matrices (up to 65%). Minor PLs (limit of detection = 4 nmol, i.e. 500 μL of an 8 μM solution) were identified in forms of phosphatidic acid, lysophosphatidic acid, and phosphatidylglycerol. Specific cross couplings and (1)H fine structures in the 2D (31)P,(1)H NMR spectra proved to be valuable for the assignment and verification of known and uncommon PLs in the samples.

Complete mitochondrial genome of the Xiangjiang barbel chub Squaliobarbus curriculus: comparative analysis of the genetic variation associated with geographical population

The barbel chub (Squaliobarbus curriculus), a kind of small commercial fish, is widespread in China. In this study, we sequenced the mitochondrial genome of the barbel chub from the Xiangjiang River. The total length of the mitochondrial genome is 16,619 bp, with the base composition of 31.19% A, 25.01% T, 27.68% C, and 16.12% G. The organization and arrangement of these genes are the same as that found in the teleosts, including 2 ribosomal RNA genes, 13 protein-coding genes, 22 transfer RNA genes, and a major noncoding control region (D-loop region). Compared with the S. curriculus collected from Jiangsu province, there were 29 mutation sites in the mitogenome sequence of Xiangjiang S. curriculus. All the mutation sites were transitions and mainly occurred in protein-coding genes (21/29), two mutation sites occurred in transfer RNA, two occurred in ribosomal RNA, and four occurred in D-loop region. Among the 21 mutation sites in protein-coding genes, 6 mutation sites resulted in amino acid mutation in ND2, ATPase6, COX3, ND4, and Cytb genes, while the others were synonymous substitutions. These results indicated that there was genetic variation in different geographical populations of S. curriculus.

Characterization of phospholipid molecular species in the edible parts of bony fish and shellfish

The phospholipid molecular species of freshwater (pangasius, Nile perch, trout), marine fish fillets (horse mackerel, European hake, common sole, European anchovy, European pilchard, Atlantic mackerel) and the edible muscle foot of bivalves (clam, mussel, oyster) commonly available in the Italian market during spring and summer were characterized by means of normal-phase high performance liquid chromatography coupled online with positive electrospray ionization ion-trap tandem mass spectrometry. From principal component analysis (PCA), it was observed that the total fatty acid profile was not suitable to differentiate among the shellfish genera. The fatty acid molecular combinations of phosphatidylcholine, the main phospholipid class, as well as phosphatidylinositol and phosphatidylethanolamine allowed for the differentiation of shellfish from the bony fishes. Phosphatidylserine and phosphatidylethanolamine plasmalogen profile allowed for the discrimination of each bony fish or shellfish genus since PS and pPE classes included a large number of fatty acid combinations that were specific for a fish genus or group.