Alternative Sources of n-3 Long-Chain Polyunsaturated Fatty Acids in Marine Microalgae

The main source of n-3 long-chain polyunsaturated fatty acids (LC-PUFA) in human nutrition is currently seafood, especially oily fish. Nonetheless, due to cultural or individual preferences, convenience, geographic location, or awareness of risks associated to fatty fish consumption, the intake of fatty fish is far from supplying the recommended dietary levels. The end result observed in most western countries is not only a low supply of n-3 LC-PUFA, but also an unbalance towards the intake of n-6 fatty acids, resulting mostly from the consumption of vegetable oils. Awareness of the benefits of LC-PUFA in human health has led to the use of fish oils as food supplements. However, there is a need to explore alternatives sources of LC-PUFA, especially those of microbial origin. Microalgae species with potential to accumulate lipids in high amounts and to present elevated levels of n-3 LC-PUFA are known in marine phytoplankton. This review focuses on sources of n-3 LC-PUFA, namely eicosapentaenoic and docosahexaenoic acids, in marine microalgae, as alternatives to fish oils. Based on current literature, examples of marketed products and potentially new species for commercial exploitation are presented.     

Application of salicylic acid induces antioxidant defense responses in the phloem of Picea abies and inhibits colonization by Ips typographus

The adaptive plasticity of Norway spruce (Picea abies) against attack by Ips typographus depends on systemic acquired resistance which involves salicylic acid (SA), and an antioxidant system both recognized as valuable stress markers in ecophysiological studies. In the presented field experiment, 100 mM SA was applied to the bark sections of Norway spruce prior to being attacked by bark beetles, in order to study interactions with antioxidants and its significance for mediating stress-tolerance under natural conditions. SA-treatments significantly elevated the total SA levels over the whole sampling period. Total glutathione (tGSH) and total cysteine (tCys) increased by 167% and 80%, respectively, two weeks after treatment, in comparison with controls. In contrast, SA-treatment caused an initial deterioration in total ascorbic acid (tASC) and enhanced the percentage of dehydroascorbic acid (DHA), but activated tASC levels over later sampling dates. The initial bark beetle attack was characterized by a significant decline in total SA levels, which was accompanied by a transient degradation and oxidation of their ascorbate-glutathione system. This initial reaction was significantly alleviated by SA-application and characterized by 175% higher tGSH contents, when compared to moderately-affected untreated trees. One month after pheromone dispensers were placed on trees, an intensification of ascorbate-glutathione system occurred within moderately-affected bark, but to a greater extent after SA-treatment. Total SA levels within SA-treated moderately-affected trees remained at the control level until June. In contrast, strong attack was characterized by a successive increase in total SA up to 252% following SA-treatment in June, whereas a 110% increase of SA was determined within severely affected control-bark. A strong attack was further characterized by a degradation of tGSH and total phenolics (tPH), a moderate increase in tASC and an oxidation of the ascorbate-glutathione pool within untreated bark. In the SA-treated trees the redox state was unaffected by severe colonization and the degradation of antioxidants was significantly alleviated. In addition, SA-treated bark had significantly less entrance holes and exhibited fewer and shorter maternal galleries than control-bark. From this perspective, exogenous SA was successfully implicated as an activator of systemic acquired resistance in Norway spruce, providing tolerance against the complex interactive effects of bark beetle attack and environmental factors.     

n-3脂肪酸的代谢和日粮α-亚麻酸强化鸡蛋的研究

在产蛋鸡日粮中添加０,２％,５％和８％胡麻油,对蛋黄和鸡肝脏的脂肪酸组成有显著影响：蛋黄中的α－亚麻酸直线增加,ＤＨＡ含量也呈增加趋势。肝脏中的ＤＨＡ含量显著提高。在日粮胡麻油添至５％时达最高。试验１４ｄ后蛋黄中ＤＨＡ和ＥＰＡ的转化达到稳定,随胡麻油添加量增加蛋黄中ＤＨＡ达到稳定的时间越长。试验表明：α－亚麻酸在鸡肝脏中进行碳链延长和脱氢过程;产蛋鸡可以将α－亚麻酸优先转化成ＤＨＡ沉积于蛋黄中;日     

饲料中添加维生素E和二十二碳六烯酸对鲤鱼生长和抗病力的影响

以建鲤鱼种为研究对象,采用3×3双因子试验设计,在基础饲料中分中分别添加0、62.5、185.5 mg·kg-1维生素E(VE),每种维生素E水平分别添加0%、0.5%、1.5%二十二碳六烯酸(DHA)共制成9种试验饲料,探讨饲料中添加不同水平维生素E和DHA对建鲤生产性能、饲料利用和抗病力的影响.结果表明,维生素E的添加对各组特定生长率没有显著影响(p＞0.05).DHA的添加显著影响鲤鱼的特定生长率(P＜005),随DHA的添加,鲤鱼特定生长率显著高于对照组fPDHA的添加亦显著影响鲤鱼的攻毒存活率(p＜0.05).随DHA的添加,鲤鱼攻毒存活率逐渐提高,当添加量达到1.5%时,鲤鱼攻毒存活率显著高于对照组(p<0.05).维生紊E和DHA相互作用对鲤鱼的攻毒存活率的影响达到显著(p<0.05),其中维生素E187.5 mg·kg-1和DHA 1.5%添加的相互作用显著高于对照组和其他各组(p＜0.05).在本试验条件下,鲤鱼饲料中添加DHA对其生长有正面效应,维生素E和DHA对鲤鱼的抗病能力具有明显的协同保护作用.维生素E的添加能增强抗病能力,但对生长的影响不明显,过量的添加亦没有促进鱼体的生长.     

Effects of varying dietary docosahexaenoic acid levels on growth,proximate composition and tissue fatty acid profile of juvenile silver pomfrets,Pampus argenteus (Euphrasen, 1788)

This study investigated the effects of varying dietary levels of decosahexaenoic acid (DHA) on growth performance, proximate composition and whole body fatty acid profiles of juvenile silver pomfret, Pampus argenteus. Triplicate groups of fish (30.55 ± 0.08 g) were fed diets containing 5.2%, 9.31% and 13.38% DHA (% of total fatty acids) or 0.85%, 1.52% and 2.18% DHA on dry diet weight for diets 1, 2 and 3 respectively. Survival was not affected by dietary DHA levels. The growth performance and feed utilization parameters of fish fed diets 2 and 3 were significantly (P < 0.05) higher than those fed diet 1, although these parameters in diets 2 and 3 did not differ significantly (P > 0.05). Whole body lipid and fatty acid profiles were influenced by dietary DHA levels. Significantly higher n‐3 fatty acids particularly DHA, DHA:EPA(eicosapentaenoic acid) ratios and n‐3:n‐6 ratios were observed in fish fed diets 2 and 3 compared to those fed diet 1. Better growth performance and higher whole body DHA:EPA (2.31, 2.29) ratios and n‐3:n‐6 ratios (2.17, 2.12) observed in fish fed diets 2 and 3, respectively, suggests that silver pomfret juveniles have a higher requirement for n‐3 fatty acids, notably DHA for optimum growth and survival.     

化学催化制备鱼油三甘酯

[目的]用化学催化方法制备鱼油三甘酯。[方法]采用酯交换反应,以鱼油乙酯和醋酸三甘酯为原料,制备三甘酯型鱼油,同时研究催化剂种类及用量(基于醋酸三甘酯的质量)、反应温度、物料比(油乙酯和醋酸三甘酯的摩尔比)、反应时间对鱼油三甘酯制备的影响,并通过液相色谱对鱼油三甘酯产物的成分进行定量分析。[结果]制备鱼油三甘酯的最佳条件为:催化剂为甲醇钠,用量为三甘酯质量的3.0%,反应温度为100℃,物料比为鱼油乙酯过量5%(相对于醋酸三甘酯),反应时间为2 h。在此最佳条件下制备产物三甘酯含量大于80%。[结论]通过此方法可实现鱼油乙酯向鱼油三甘酯的转化,成本较低,扩大了鱼油类产品在医药和保健品中的应用。     

Chemical Composition of Fresh and Salted Lumpfish (Cyclopterus lumpus) Roe

The original "Eskimo" cardiovascular health benefit of omega-3 fatty acids was ascribed to EPA (eicosapentaenoic acid). The two readily available fish body oils (from U.S. menhaden and Japanese sardines) have approximately 180 mg of EPA/gram, accompanied by much less (120 mg) DHA (docosahexaenoic acid). The EPA was recognized as the source of a prostaglandin (PGI₃) acting as an agent to keep the vascular walls soft and flexible, thus hindering atherosclerosis and vascular constriction, but DHA presented a problem as no such role for it was known. Australian researchers identified DHA as preventing cardiac arrhythmia because they used tuna body oil (DHA ~5 x EPA) in their research. Generally our analyses of salmon muscle triglycerides seem to show DHA > EPA. Total salmon muscle lipids in fillets obtain extra DHA from phospholipids. In the United Kingdom an official medical body now recommends eating fish twice a week and "oily" fish once a week. Examination of DHA for a legitimate health claim in the cardiovascular system, and in infant neural developments and nutrition, and maternal nutrition, offers an alternative market exploiting the most recent developments. These matters should be investigated by the salmon aquaculture industry.     

饲粮胆碱和裂殖壶菌油联合添加促进二十二碳六烯酸在鸡蛋卵黄中的富集

本试验旨在研究饲粮添加胆碱与裂殖壶菌油(Schizochytrium oil,SO)对鸡蛋卵黄脂质及二十二碳六烯酸(DHA)富集的影响。选取26周龄京红蛋鸡288只,分4组(每组6个重复,每重复12只鸡)。采用2×2因子试验设计,饲粮添加胆碱(500和1 000 mg/kg)和SO(0和0.5%)为2个主效应,共配制4种等氮等能饲粮。预试期1周,正试期8周。结果表明:1)试验期内,各组生产性能和蛋品质均无显著差异(P0.05)。2)各组卵黄中干物质、粗脂肪、胆固醇及甘油三酯含量均无显著差异(P0.05)。1 000 mg/kg胆碱组卵黄总磷脂含量显著高于500 mg/kg胆碱组(P0.05)。胆碱和SO对卵黄总磷脂含量有显著交互作用(P=0.04),1 000 mg/kg胆碱+0.5%SO组卵黄总磷脂含量最高。3)0.5%SO显著提高卵黄n-3多不饱和脂肪酸(PUFA)和DHA含量(P0.05),显著降低n-6 PUFA含量及n-6 PUFA/n-3 PUFA值(P0.05)。胆碱和SO对卵黄中n-3 PUFA(P0.001)、n-6 PUFA(P=0.01)及DHA(P0.001)含量和n-6 PUFA/n-3 PUFA值(P=0.01)有显著交互作用,1 000 mg/kg胆碱+0.5%SO组卵黄中n-3PUFA和DHA含量显著高于其他组(P0.05),且n-6 PUFA含量及n-6 PUFA/n-3 PUFA值显著低于其他组(P0.05)。综上,本试验条件下,饲粮中1 000 mg/kg胆碱和0.5%SO联合添加可促进卵黄DHA富集,且对蛋鸡生产性能和蛋品质无显著影响。     

Docosahexaenoic Acid-Acylated Astaxanthin Esters Exhibit Superior Renal Protective Effect to Recombination of Astaxanthin with DHA via Alleviating Oxidative Stress Coupled with Apoptosis in Vancomycin-Treated Mice with Nephrotoxicity

Prevention of acute kidney injury caused by drugs is still a clinical problem to be solved urgently. Astaxanthin (AST) and docosahexaenoic acid (DHA) are important marine-derived active ingredients, and they are reported to exhibit renal protective activity. It is noteworthy that the existing forms of AST in nature are mainly fatty acid-acylated AST monoesters and diesters, as well as unesterified AST, in which DHA is an esterified fatty acid. However, no reports focus on the different bioactivities of unesterified AST, monoesters and diesters, as well as the recombination of DHA and unesterified AST on nephrotoxicity. In the present study, vancomycin-treated mice were used to evaluate the effects of DHA-acylated AST monoesters, DHA-acylated AST diesters, unesterified AST, and the recombination of AST and DHA in alleviating nephrotoxicity by determining serum biochemical index, histopathological changes, and the enzyme activity related to oxidative stress. Results found that the intervention of DHA-acylated AST diesters significantly ameliorated kidney dysfunction by decreasing the levels of urea nitrogen and creatinine, alleviating pathological damage and oxidative stress compared to AST monoester, unesterified AST, and the recombination of AST and DHA. Further studies revealed that dietary DHA-acylated AST esters could inhibit the activation of the caspase cascade and MAPKs signaling pathway, and reduce the levels of pro-inflammatory cytokines. These findings indicated that the administration of DHA-acylated AST esters could alleviate vancomycin-induced nephrotoxicity, which represented a potentially novel candidate or therapeutic adjuvant for alleviating acute kidney injury.     

Influence of Metabolic Status and Diet on Early Pregnant Equine Histotroph Proteome: Preliminary Findings

Insulin resistance (IR) is characterized by an increase in biomarkers of systemic inflammation and susceptibility to laminitis in horses. Impacts on reproduction include a lengthened interovulatory period in horses. Dietary omega-3 (docosahexaenoic acid [DHA]) promotes anti-inflammatory processes, has been implicated in health benefits, and can reduce cytokine secretion. This preliminary study investigated the impact of IR as well as the influence of dietary supplementation (DHA) on the uterine fluid proteome in early pregnant horses. Mares were artificially inseminated; uterine fluid and embryos were collected on d 12.5 after ovulation. Uterine fluid was pooled for metabolic and diet categories (n = 8; n = 2 per metabolic and dietary status) and concentrated, and the proteome was analyzed using tandem mass spectrometry (iTRAQ). Five proteins met differential abundance criteria (±1.5-fold change, P < .05) in all comparisons (Control C, IS vs. C, IR; C, IS vs. DHA, IS; C, IR vs. DHA, IR). Serum amyloid A, afamin, and serotransferrin were upregulated in C, IR mares but downregulated in DHA, IR mares when compared to C, IS and C, IR, respectively. Quantitative PCR supported mass spectrometry results. The presence of serum amyloid A and serotransferrin in histotroph of IR mares potentially indicates an inflammatory response not seen in IS counterparts. These preliminary findings provide novel evidence on the potential impact of insulin resistance and DHA supplementation on the secreted equine uterine proteome during early pregnancy.