花生四烯酸生物活性及其对机体的免疫作用

花生四烯酸(Arachidonic Acid)是一种重要的多不饱和脂肪酸,在动物机体中有着广泛的生理作用,它作为一种极为重要的结构脂类广泛存在于哺乳动物的器官、肌肉和血液组织中,是动物的一种必需脂肪酸,其作为饲料添加剂在动物繁殖,抗病力,增强动物机体免疫中得以广泛开发,有广大的应用前     

脂肪酸的营养功能

膳食脂肪是人体需要的重要营养素之一,脂肪酸是脂肪的重要构成成分。脂肪酸根据碳链长短、饱和程度、营养关系可分为不同的种类,不同的种类具有不同物理化学特性和生理功能。文章分别介绍了不饱和脂肪酸、单不饱和脂肪酸、多不饱和脂肪酸的营养及其功能特性,并为合理摄取脂肪酸提供了一些建议。     

海洋微藻多不饱和脂肪酸研究进展

多不饱和脂肪酸在人和动物的生理活动中具有重要的作用.海洋微藻中富含多不饱和脂肪酸.因此,利用海洋微藻生产多不饱和脂肪酸具有广阔的前景.本文综述了温度、光辐射、培养液的化学组成、通气量、存贮和培养方式等环境影响因子对海洋微藻中多不饱和脂肪酸含量的影响,以及利用光生物反应器培养微藻的现状,为后续的研究奠定了理论基础.     

微藻花生四烯酸的研究进展

微藻蕴量丰富、种类繁多,在地球上大约存在3万余种不同门类的微藻。近年来的研究表明,微藻中存在着丰富的、结构独特的有机化合物,如多不饱和脂肪酸酸(PUFA)、多糖、抗生素、毒素等。尤其是微藻体内含有的多不饱和脂肪酸越来越引起人们的重视,并且日渐成为人们获取PUFA的重     

鱼类出塘应激与体内氧化损伤（下）

细胞膜的流动性是保证动物细胞功能正常的必要条件.由于鱼类是变温动物,为了保证低温时细胞膜的流动性,富含大量多不饱和脂肪酸是鱼类细胞膜相对于陆生恒温动物的典型特征.而这些大量存在的多不饱和脂肪也是导致细胞容易遭受自由基攻击的关键原因.在消除自由基的过程中,各种酶及抗氧化分子协同作用共同维持体内氧化还原状态的平衡,避免自由基对细胞造成进一步的伤害.未能有效清除的自由基将进一步攻击细胞膜上的多不饱和脂肪酸,从而启动不饱和脂肪酸自动氧化的链式反应.     

中华鲟在鱼卵和1~+龄阶段对脂肪酸选择利用的研究

为研究中华鲟对脂肪酸的选择利用,采用国标方法,对野生与人工养殖中华鲟成熟鱼卵和肌肉的脂肪酸组成进行了测定分析。试验结果显示:野生中华鲟卵细胞中C18:1和C22:6(DHA)脂肪酸的含量高于养殖的中华鲟成熟卵细胞;在相同的养殖环境和投饲策略下,野生中华鲟幼鱼合成或富集n-3多不饱和脂肪酸的能力高于养殖的中华鲟幼鱼。研究表明,中华鲟亲鱼在发育过程中对营养素的累积具有差异性,多不饱和脂肪酸,尤其是DHA、EPA和ARA脂肪源,对中华鲟亲鱼性腺发育和幼鱼生长发育具有重要意义。     

裂壶藻及其制品在水产苗种培育中的应用

众所周知，海洋鱼类体内所含有的n－３系列多不饱和脂肪酸（PUFA）系由海洋浮游藻类所合成，经浮游动物、鱼类的食物链转移，最终积累在鱼体和生殖细胞的卵黄内。在胚胎发育过程中，积累在卵黄内的n－３系列多不饱和脂肪酸源源不断地供给发育中的胚胎所需。当积累在卵黄内的必需脂肪酸消耗殆尽时，仔鱼不得不从外界摄取的食物中继续得到自身不能合成的这类多不饱和脂肪酸（PUFA或HUFA），特别是二十碳五烯酸（２０：５n－３；EPA）和二十二碳六烯酸（２２：６n－３；DHA）。由于海水鱼类、虾类自身不能合成这类多不饱和脂肪酸，故将…     

梅奇酵母C14菌株的生化组成分析

通过对梅奇酵母C14菌株的生化组成进行分析,发现梅奇酵母C14菌株具有水产动物饵料生物的营养价值。但是,该菌株缺乏多不饱和脂肪酸EPA和DHA,作为幼体饵料使用时,需要添加富含这两种多不饱和脂肪酸的藻类作为补充。     

外源核苷酸对异育银鲫幼鱼消化酶活性的影响

核苷酸是动物体内一种重要的低分子化合物,对动物体的胃肠道功能、机体免疫系统、机体抗氧化功能以及动物的生产性能等很多方面有着重要影响,已经被认为是一种新型的饲料添加剂.     

3种淡水鱼肌肉脂质的组成及营养评价

以拉萨河拉萨裸裂尻鱼(Schizopygopsis younghusbandi)、拉萨裂腹鱼(Schizothorax waltoni)、双须叶须鱼Ptychobarbus dipogon)为材料,研究了其肌肉中脂质的组成和含量。结果显示:10种含量最丰富的脂肪酸分别是饱和脂肪酸16∶0和18∶0;单不饱和和脂肪酸16∶1n-9、18∶1n-9和18∶1n-7;n-3型多不饱和脂肪酸20∶5n-3,22∶5n-3和22∶6n-3和n-6型多不饱和脂肪酸18∶2n-6和20∶4n-6。结果表明拉萨河鱼类的脂肪酸模型跟深海鱼类相似,而且n-3型多不饱和脂肪酸的含量相对较高。     

The fatty acid compositions of established fish cell lines after long-term culture in mammalian sera

The effect of long-term culture of fish cells in mammalian serum on the phospholipid fatty acid composition was investigated. All the cell lines studied had much lower levels of polyunsaturated fatty acids (PUFA) than those found in intact fish tissues. In particular (n-3) PUFA were considerably depleted in the cultured cell lines, leading to very low (n-3)/(n-6) ratios in all the phospholipid classes. In general the cells were rich in 18:1, 16:0, 18:0 and 16:1 with 20:4(n-6) and 22:6(n-3) as the major PUFA. The fatty acid composition reflected the composition of the fetal calf serum added to the media rather than their fish tissue origins. The results were discussed in relation to the roles of PUFA in general cell metabolism and more specifically the role of (n-3) PUFA in fish cells.     

Does dietary tocopherol level affect fatty acid metabolism in fish?

Fish are a rich source of the n-3 polyunsaturated fatty acids (PUFA), particularly the highly unsaturated fatty acids (HUFA) eicosapentaenoic (EPA; 20:5n-3) and docosahexaenoic (DHA; 22:6n-3) acids, which are vital constituents for cell membrane structure and function, but which are also highly susceptible to attack by oxygen and other organic radicals. Resultant damage to PUFA in membrane phospholipids can have serious consequences for cell membrane structure and function, with potential pathological effects on cells and tissues. Physiological antioxidant protection involves both endogenous components, such as free-radical-scavenging enzymes, and exogenous dietary micronutrients including tocopherols and tocotrienols, the vitamin E-type compounds widely regarded as the primary lipid-soluble antioxidants. The antioxidant activities of tocopherols are imparted by their ability to donate their phenolic hydrogen atoms to lipid (fatty acid) free radicals, resulting in the stabilization of the latter and the termination of the lipid peroxidation chain reaction. However, tocopherols can also prevent PUFA peroxidation by acting as quenchers of singlet oxygen. Recent studies on marine fish have shown correlations between dietary and tissue PUFA/tocopherol ratios and incidence of lipid peroxidation, as indicated by the levels of thiobarbituric-acid reactive substances (TBARS) and isoprostanes. These studies also showed that feeding diets containing oxidized oil significantly affected the activities of liver antioxidant defence enzymes and that dietary tocopherol partially attenuated these effects. However, there is evidence that dietary tocopherols can affect fatty acid metabolism in other ways. An increase in membrane PUFA was observed in rats deficient in vitamin E. This was suggested to be due to overproduction of PUFA arising from increased activity of the desaturation/elongation mechanisms responsible for the synthesis of PUFA. Consistent with this, increased desaturation of 18:3n-3 and 20:5n-3 in hepatocytes from salmon fed diets deficient in tocopherol and/or astaxanthin has been observed. Although the mechanism is unclear, tocopherols may influence the biosynthesis of n-3PUFA through alteration of cellular oxidation potential or peroxide tone.     

Muscle fatty acid composition and oxidative stress indices of Arctic charr, Salvelinus alpinus (L.), in relation to dietary polyunsaturated fatty acid levels and temperature

The influence of feeding high levels of polyunsaturated fatty acids (PUFA) on muscle fatty acid composition and indices of oxidative damage was examined in Arctic charr, Salvelinus alpinus (L.). All diets contained 100 g kg^?1 lipid of dry weight. Two diets contained marine fish oils giving a PUFA level of 250 g kg^?1 and 500 g kg^?1 of lipid. The remaining two diets contained vegetable oils high in either 18:2n-6 or 18:3n-3, giving a PUFA level of more than 500 g kg^?1 of dietary lipid. The charr were maintained at 8°C until their weight doubled, and were then transferred to 0.8°C for 30 days. Growth was similar in all groups. The fatty acid compositions of muscle were influenced by dietary PUFA but were less diverse than those of the diets. The overall pattern of fatty acid compositions indicated preferential desaturation and elongation of n-3 PUFA coupled with selective oxidation of 18:2n-6. Total n-3 PUFA content in TAG was always lowered compared with the diet, suggesting a specific mechanism for the removal of these fatty acids. Subjecting the fish to low temperature increased PUFA content in muscle of charr fed the 250 g kg^?1 marine n-3 PUFA diet, but had no effect on the other treatments. For fish at 8°C, no significant differences were found between groups in terms of haematocrit, plasma alanine aminotransferase (ALAT), and plasma and muscle thiobarbituric acid reactive substances (TBARS), although there was a tendency towards increased levels of TBARS in the group receiving 500 g kg^?1 marine n-3 PUFA of lipid. Subjecting the muscle to forced oxidative conditions resulted in increases in TBARS in all groups, particularly those fed 500 g kg^?1 marine n-3 PUFA. Lowering the environmental temperature corresponded with a further increase in the plasma ALAT and muscle TBARS in this group. It is concluded that feeding diets containing high levels of long-chain n-3 PUFA may be detrimental to the fish's health and flesh quality, particularly at low environmental temperatures.     

Dietary lipid sources affect the performance of Nile tilapia at optimal and cold,suboptimal temperatures

Five sources of dietary fatty acids (fish, linseed, sunflower, olive and coconut oils) were evaluated in juvenile Nile tilapia in two trials: at optimal (28°C) and suboptimal (22°C) temperatures lasting 9 and 12 weeks, respectively. At 28°C, there was no clear effect of dietary source on fish growth, but at 22°C, the highest daily weight gain occurred in fish fed sunflower, linseed and fish oil. Feed efficiency and apparent net protein utilization increased as the amount of unsaturated fatty acids, especially n‐3 polyunsaturated fatty acids (PUFA), in the diet increased. Coconut oil, which is rich in saturated fatty acids (SFA), led to the worst growth results, especially at 22°C, with the lowest weight gain, feed intake and feed utilization by tilapia. The body fatty acid profile, in % of total fatty acids, was dependent on diet composition. However, for all treatments, PUFA body content increased with the decrease in temperature, but SFA and monounsaturated fatty acids remained the primary contributors to the body profile. Either fish oil or vegetable oil may be used as sources of dietary fatty acids for Nile tilapia, but at suboptimal temperatures, a dietary source containing more PUFA and less SFA improves performance.     

Aurantiochytrium sp. meal as DHA source in Nile tilapia diet,part II: Body fatty acid retention and muscle fatty acid profile

Nile tilapia juveniles (8.35 ± 0.80 g) were fed on four levels (0.0%; 0.5%; 1.0%; 2.0%, 4.0%) of Aurantiochytrium sp. meal (ALL‐G‐RICH?), a source of docosahexaenoic acid (DHA). The 1% Aurantiochytrium sp. meal diet was compared to a control diet, which contained the same amount of DHA as cod liver oil (CLO) at 1.7% diet. Groups of 25 fish were stocked in 100 L tanks and fed twice daily until apparent satiation, for 57 days, at 28°C. Increasing dietary Aurantiochytrium sp. meal reduced the body retention of DHA and n‐3 polyunsaturated fatty acids (n‐3 PUFA) but increased the body retention of alpha‐linolenic (α‐LNA), linoleic (LOA) and n‐6 polyunsaturated fatty acids (n‐6 PUFA). Fatty acid profile in tilapia muscle was affected by increasing dietary inclusions of Aurantiochytrium sp. meal, with an increase in DHA, α‐LNA, n‐3 PUFA and n‐3 long chain‐polyunsaturated fatty acids (n‐3 LC‐PUFA) but a decrease in monounsaturated fatty acids (MUFA), n‐6 PUFA and n‐6 long‐chain polyunsaturated fatty acids (n‐6 LC‐PUFA). There was a larger body retention of DHA, α‐LNA, LOA, n‐3 PUFA and n‐6 PUFA fatty acids and a higher percentage of DHA, n‐3 PUFA and n‐3 LC‐PUFA in muscle fatty acid profile in fish fed on CLO diets than in those fed on 1% Aurantiochytrium sp. Therefore, Aurantiochytrium sp. meal is an alternative source of DHA for Nile tilapia diets.     

Complete repertoire of long‐chain polyunsaturated fatty acids biosynthesis enzymes in a cyprinid,silver barb (Barbonymus gonionotus): Cloning,functional characterization and dietary regulation of Elovl2 and Elovl4

The silver barb (Barbonymus gonionotus) is a valuable cyprinid with good deposition of long‐chain polyunsaturated fatty acids (LC‐PUFA) such as docosahexaenoic acid (DHA). We have previously isolated a fatty acyl desaturase (Fads2) and elongase (Elovl5), which fulfils the production of eicosapentaenoic acid (EPA) and arachidonic acid (ARA) from C18 polyunsaturated fatty acid (PUFA) substrates. The isolation, functional characterization and dietary regulation of two elongases, Elovl2 and Elovl4, are reported here. The Elovl2 displayed the capacity to elongate C20 and C22 PUFA substrates, while the showed low activities towards saturated fatty acids and C22 PUFA substrates. This discovery validates the existence of a complete set of enzymes of LC‐PUFA in silver barb. The elovl2 showed higher expression in liver, in limited dietary LC‐PUFA intake conditions. As for Elovl4, tissue expression showed prominence in eye tissue. We also showed that the expression of both genes was upregulated when fish was fed with diets devoid of LC‐PUFA. Fatty acid composition analysis indicates the utilization of C18 polyunsaturated fatty acids for LC‐PUFA biosynthesis.     

Biochemical changes during vitellogenesis in the red claw crayfish,Cherax quadricarinatus (von Martens)

Redclaw crayfish (Cherax quadricarinatus) females at different stages of vitellogenesis were sampled to investigate variations in soluble protein, lipid and water content and in the amino acid and fatty acid composition of the hepatopancreas and ovaries. During vitellogenesis, the changes in the content of soluble proteins and lipids in the hepatopancreas and ovaries were dependent on both diet and the reserves from the hepatopancreas. However, in comparison to the ovary, the fluctuation of the amino acid composition in the hepatopancreas suggested that the protein resources mobilized from this organ was compensating for those gained from feeding. Changes in the fatty acid composition of the hepatopancreas showed limited compensatory function as for the quick accumulation of lipids in the ovaries. The proportional amounts of saturated fatty acids/mono‐unsaturated fatty acids/poly‐unsaturated fatty acids (PUFA) and the predominant fatty acids in both tissues indicated that the mobilization and utilization of fatty acids in freshwater species are different from that in marine species. Based on the redclaw's feeding habits, the commercial pellets used in this study may not be optimal, and a diet with less PUFA may suffice for its vitellogenesis and reduce the feeding costs.     

Variations in fatty acids composition of pikeperch (Sander lucioperca) liver with respect to gonad maturation

Abstract –  We examined seasonal variations in liver condition factor, total lipid and fatty acid composition of maturing pikeperch ( Sander lucioperca) from Lake Eğirdir, Turkey. The spawning of pikeperch in Eğirdir Lake started in March, continued very fast during May and gradually ended in July as determined by measuring the gonadosomatic index. The total lipid content of male and female liver reached its highest level in September and November (the end of dense feeding period during which temperature decreased sharply), but declined to the lowest level in May (just after spawning). The highest level of liver condition factor was observed in January and March during which gonads mature rapidly. Palmitic acid was the predominant saturated fatty acid (SFA) in female and male liver. The ratio of monounsaturated fatty acids (MUFA) was higher than that of polyunsaturated fatty acids (PUFA) in both sexes. Docosahexaenoic acid (22:6 n -3), eicosopentaenoic acid (20:5 n -3) and arachidonic acid (20:4 n -6) were the predominant PUFA. Seasonal variations in PUFA were more evident than that in other fatty acids. PUFA, especially the n -3 fatty acids ratio, increased to the maximum level during the sharp decreases in temperature (in November). However, the amount of PUFA decreased to the lowest level in reproductive period. The results suggest that the ratio of pikeperch liver fatty acids is influenced by gonad maturation and temperature variations and that pikeperch requires a large amount of PUFA and the n -3 fatty acids for the development of gonads.     

不同脂肪源对真鲷幼鱼生长、存活及体内脂肪酸组成的影响

真鲷幼鱼摄食缺乏多不饱和脂肪酸(PUFA)饵料时,其生长增重率和存活率比摄食富含PUFA配合饵料或玉筋鱼鱼糜的明显下降。幼鱼摄食含有不同脂肪酸饵料时,其肌肉和肝脏组极性或非极性脂中脂肪酸组成都有变化。肌肉和肝脏极性脂中的PUFA比非极性脂中PUFA含量高,并且当饵料中不能提供足够的PUFA时,非极性脂中的PUFA下降明显,而极性脂中的PUFA变化较小,被优先贮存。真鲷幼鱼肌肉和肝脏组织缺乏n-9、n-6和n-3相互转化的能力。因此,为提高幼鱼的生长增重率和存活率,必须保证饵料中含有足够的PUFA。     

Effects of salinity on the fatty acid compositions of total lipid and individual glycerophospholipid classes of Atlantic salmon (Salmo salar) and turbot (Scophthalmus maximus) cells in culture

Cells from a relatively stenohaline marine species, turbot (Scophthalmus maximus) (TF) and an anadromous species, Atlantic salmon (AS) were cultured in media supplemented with NaCl to produce OPs varying from 300 to 500 mOsm kg^–1 and the direct effects of OP (salinity) on the fatty acid compositions of the main glycerophospholipid classes were determined. The most dramatic effects of salinity on total lipid fatty acids were observed in polyunsaturated fatty acids (PUFA) in TF cells. There was a graded decrease in the percentage of 18:2n-9, and consequently total n-9 PUFA, and concomitantly increased percentages of both total n-3 and n-6 PUFA with increasing salinity. The increased n-3 and n-6 PUFA was due to significantly increased percentages of the major fatty acids in each of these groups, namely 22:6n-3 and 20:4n-6, respectively. The reciprocal changes in n-9 PUFA and n-3/n-6 PUFA in TF cell total lipid resulted in the percentage of total PUFA not being significantly affected by changes in salinity. The graded decrease in 18:2n-9 with increasing salinity in TF cells was observed in all the major glycerophospholipids but especially PE, PI and PS. Increasing salinity resulted in graded increases in the percentages of 22:6n-3 in PE and PS in TF cells. The quantitatively greatest increase in the percentage of n-6 PUFA in TF cells occurred with 20:4n-6 in PC, PE and PL. There were less significant changes in the fatty acid compositions of glycerophospholipids in AS cells. However, the proportion of total n-3 + n-6 PUFA in PE varied reciprocally with the proportion of dimethylacetals in response to salinity. Similar reciprocal changes between fatty acids in response to salinity were also evident in the quantitatively more minor glycerophospholipids PS and Pl. In PS, the percentage of 22:6n-3 was significantly lower at 400 mOsm kg^–1 whereas the proportion of total monoenes was significantly higher at that salinity. A similar inverse relationship between total monoenes and 20:4n-6 (and, to a lesser extent total saturates) in response to salinity was noted in PI. The results show that environmental salinity, without whole-body physiological stimuli, has direct effects on the fatty acid composition of major glycerophospholipid classes in fish cells and that these effects differ in cells from different fish speciesAbbreviations ANOVA analysis of variance - BHT butylated hydroxytoluene - BSA bovine serum albumin - DMA dimethylacetals - EMEM Eagle's minimal essential medium - FCS fetal calf serum - GC gas chromatography - HBSS Hank's balanced salt solution (without Ca²⁺ and Mg²⁺) - OP osmotic pressure - PC phosphatidylcholine - PE phosphatidylethanolamine - PI phosphatidylinositol - PS phosphatidylserine - PUFA polyunsaturated fatty acid - TLC thin-layer chromatography