Arachidonic acid, arachidonic/eicosapentaenoic acid ratio, stearidonic acid and eicosanoids are involved in dietary-induced albinism in Senegal sole (Solea senegalensis)

Senegal sole larvae were fed live prey enriched with different amounts of arachidonic acid (ARA, 20:4n‐6) and eicosapentaenoic acid (EPA, 20:5n‐3) to re‐evaluate the effect of these two fatty acids on flatfish pigmentation. Echium oil, a plant‐derived oil rich in gamma‐linolenic acid (18:3n‐6) and stearidonic acid (18:4n‐3) was also used as a component of one of the enrichment emulsions. Although ARA content did not have any effect on growth there was a clear influence on pigmentation that correlated clearly with prostaglandin production. Inclusion of Echium oil, on the contrary, exerted a positive effect on pigmentation rate even though dietary ARA levels were as high as in the other emulsions. The relationships between dietary ARA levels and dietary ARA/EPA ratio, prostaglandin production and pigmentation are discussed.     

Effects of different dietary arachidonic acid : docosahexaenoic acid ratios on phospholipid fatty acid compositions and prostaglandin production in juvenile turbot (Scophthalmus maximus)

Five purified diets containing AA (20:4n-6) at 0.02–0.78% dry weight and DHA (22:6n-3) at 0.93–0.17% dry weight were fed to duplicate groups of juvenile turbot (Scophthalmus maximus) of initial weight 0.87 g for a period of 11 weeks. The dietary DHA:AA ratio ranged from 62 to 0.2. Incorporation of AA into liver phospholipids increased with increasing dietary AA input. Phospholipids from fish fed diets containing 0.02, 0.06 and 0.11% of dry weight as AA generally contained less AA compared to fish fed fish oil while those fed diets containing 0.35 and 0.78% of dry weight as AA had higher AA levels in their phospholipids. The highest levels of AA were found in PI but the greatest percentage increase in AA incorporation was in PE and PC. Brain phospholipid fatty acid compositions were less altered by dietary treatment than those of liver but DHA content of PC and PE in brain was substantially lower in fish fed 0.93% pure DHA compared to those fed fish oil. This suggests that dietary DHA must exceed 1% of dry weight to satisfy the requirements of the developing neural system in juvenile turbot. In both tissues, (20:5n-3) concentration was inversely related to both dietary and tissue PI AA concentration. Similar dietary induced changes in AA, EPA and DHA concentrations occurred in the phospholipids of heart, gill and kidney. PGE₂ and 6-ketoPGF₁ were measured in homogenates of heart, brain, gill and kidney. In general, fish fed the lowest dietary AA levels had reduced levels of prostaglandins in their tissue homogenates while those fed the highest level of AA had increased prostaglandin levels, compared to fish fed fish oil. In brains, the PGE₂ concentration was only significantly increased in fish fed the highest dietary AA.Abbreviations AA arachidonic acid - DHA docosahexaenoic acid - EFA essential fatty acid - EPA eicosapentaenoic acid - HPTLC high performance thin-layer chromatography - HUFA highly unsaturated fatty acid - PC phosphatidylcholine - PE phosphatidylethanolamine - PGE prostaglandin E - PGE prostaglandin E - PI phosphatidylinositol - PS phosphatidylserine - PUFA polyunsaturated fatty acid - TLC thin-layer chromatography     

叶酸对皱纹盘鲍脂肪酸组成的影响

以皱纹盘鲍幼鲍Haliotis discus hannaiIno(平均壳长:13.90±0.01mm;平均体重:482.2±2.2mg)为研究对象,在室内循环水养殖系统中进行112d的摄食生长实验,以海带为对照,探讨饲料中不同叶酸含量(0.06、1.44、2.86、5.88、14.27、35.71mg/kg饲料)对皱纹盘鲍脂肪酸组成的影响。实验结果表明,(1)叶酸缺乏可显著降低皱纹盘鲍C20∶4n-6和C20∶5n-3的含量(P<0.05),却显著提高C18∶3n-3和C22∶6n-3的含量(P<0.05);(2)海带与实验基础饲料中的脂肪酸组成存在显著差异,海带中的C14∶1、C16∶0、C18∶1n-9、C18∶3n-3、C20∶4n-6、C20∶5n-3含量显著高于饲料组(P<0.05),而C18∶0、C18∶1n-7、C18∶2n-6、C20∶0、C22∶6n-3均显著低于饲料组(P<0.05);(3)海带组鲍鱼的C20∶4n-6、C20∶5n-3显著高于饲料组鲍鱼(P<0.05),而C18∶1n-9、C18∶1n-7、C18∶2n-6、C22∶6n-3则显著低于饲料组鲍鱼(P<0.05)。(4)C16∶0、C16∶1、C18∶0在鲍鱼体内的含量比较稳定,不受饲料中叶酸含量和脂肪酸组成的显著影响(P>0.05)。这些结果说明,饲料中叶酸缺乏导致皱纹盘鲍脂肪酸组成发生改变,很可能抑制C18∶2n-6和C18∶3n-3的碳链延长和去饱和作用,从而减少C20∶4n-6和C20∶5n-3的合成。此外,饲料中的脂肪酸组成也是影响皱纹盘鲍体组织脂肪酸组成的一个重要因素。     

Effect of dietary arachidonic acid, eicosapentaenoic acid and docosahexaenoic acid on survival, growth and pigmentation in larvae of common sole (Solea solea L.)

Evidence confirms that polyunsaturated fatty acids (PUFAs), arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid, DHA are involved in growth as well in pigmentation of marine fish larvae.In the present study we examined the performance of common sole larvae reared on Artemia enriched with 10 formulated emulsions, differing in inclusions of ARA, EPA, and DHA. The specific growth rate of the sole larvae until late metamorphosis, 21 days after hatching (dah) was 20 to 27% d^− 1. Even though the relative tissue essential fatty acid (EFA) concentrations significantly reflected dietary composition, neither standard growth nor larval survival were significantly related to the absolute concentrations of ARA, EPA and DHA or their ratios. This suggests low requirements for essential polyunsaturated fatty acids (PUFAs) in common sole. Malpigmentation was significantly related to increased dietary ARA content. However, pigmentation was not affected by inclusion levels of EPA or DHA when ARA was high. This, and no relation between DHA: EPA or ARA: EPA ratios and pigmentation and only a weak relation to ARA: DHA ratio, advocate for that it is the absolute concentration of ARA in larval tissues, that is responsible for malpigmentation rather than the relative concentration to other PUFAs.Within malpigmentation, the trait “albinism” was characterised by an abnormal incomplete eye migration, but this trait is suggested not to be related to dietary ARA. Furthermore, albinism resulted in a lower growth rate, which suggests that visual aberrations affected prey capture.     

不同生长时期红螯螯虾肌肉和肝胰腺内氨基酸和脂肪酸变化分析

为了研究不同生长时期红螯螯虾(Cherax quadricarinatus)肌肉和肝胰腺内脂肪酸和氨基酸的动态变化,选取90 d (第二性征未发育)、140 d (第二性征发育成熟)和180 d (性腺发育成熟)的红螯螯虾,分别测定其肌肉和肝胰腺内氨基酸和脂肪酸的含量。结果显示,90 d红螯螯虾肌肉中的必需氨基酸总量显著高于其他2个时期(P<0.05);而红螯螯虾肝胰腺内必需氨基酸总量和非必需氨基酸总量均随着日龄增加而逐渐下降。比较不同生长时期肌肉中脂肪酸含量发现,随着日龄增长,饱和脂肪酸(SFA)含量呈下降趋势;而单不饱和脂肪酸(MUFA)含量呈先上升后下降的变化趋势,140 d含量最高[(25.69±0.42)%];多不饱和脂肪酸(PUFA)含量呈上升的变化趋势。肝胰腺中SFA含量在 3个生长时期内无显著性差异(P>0.05),MUFA含量呈先上升后下降的变化趋势,140 d含量最高[(37.44±0.59)%],而PUFA含量变化与MUFA正好相反。营养价值评估结果显示,180 d (可上市销售)的红螯螯虾肌肉内必需氨基酸指数(49.96%)高于联合国粮农组织/世界卫生组织(FAO/WHO)评分模式(31.50%)和全鸡蛋蛋白质模式(43.10%),是较为理想的优质食物蛋白源。由上可知,在不同生长时期,肌肉和肝胰腺中的氨基酸、脂肪酸的主要消耗不同,研究结果对了解不同生长时期红螯螯虾营养需求、开发红螯螯虾配合饲料提供了参考依据。     

Effect of soy oil containing stearidonic acid on growth performance and fillet fatty acid composition of Atlantic salmon

The effects of stearidonic acid (SDA; 18:4n‐3) derived from SDA‐enhanced, genetically modified soybeans (Monsanto Company, St Louis, MO, USA) on growth performance and fatty acid (FA) composition of large Atlantic salmon (Salmo salar; 2.1 kg initial weight) were evaluated. There was a stepwise decrease in feed intake and subsequent weight gain of immature Atlantic salmon with increased replacement of fish oil by SDA soy oil from 0%, 50% to 100% added oil. SDA increased and n‐3 highly unsaturated FA (n‐3 HUFA; eicosapentaenoic acid + docosahexaenoic acid) decreased in the diet and corresponding fillet with increased SDA oil inclusion. Salmon with the same weight gain fed SDA oil compared with rapeseed oil at 50% fish oil replacement had similar n‐3 HUFA fillet levels indicating little or no increased synthesis of n‐3 HUFA from SDA for deposition in the fillet. However, elongation of dietary SDA to 20:4n‐3 for deposition in the fillet of SDA oil fed fish was indicated. The increased SDA and 20:4n‐3 in the fillet of Atlantic salmon fed SDA oil compared with rapeseed oil at 50% fish oil replacement may be more effective as precursors for EPA in humans than 18:3n‐3 which was in the fillet at similar levels.     

Fatty acid composition,osmolality, Na+, K+‐ATPase activity,cortisol content and antioxidant status of rainbow trout (Oncorhynchus mykiss) in response to various dietary levels of eicosapentaenoic acid and docosahexaenoic acid

This study was conducted to evaluate the effect of dietary eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) levels on the fatty acid composition, salinity tolerance and antioxidant status of rainbow trout (Oncorhynchus mykiss). Four diets were formulated with total EPA and DHA contents of 5.41, 9.55, 13.97 and 17.88 g/kg (abbreviated as ED‐5.41, ED‐9.55, ED‐13.97 and ED‐17.88 respectively). Rainbow trout (initial weight of 90.61 ± 9.25 g) were fed the experimental diets for 8 weeks to accumulate significant differences in fatty acid composition and subsequently underwent salinity acclimation. Our results indicated that high dietary EPA and DHA significantly improved the EPA and DHA content in fish tissues. The serum osmolality of fish returned to their freshwater values in the ED‐9.55, ED‐13.97 and ED‐17.88 groups. The Na⁺, K⁺‐ATPase (NKA) activity of fish in the ED‐13.97 group changed dramatically to adapt the fish to the hypertonic environment. Moreover, there was no significant difference in the serum cortisol concentration and liver catalase (CAT) activity of fish in the ED‐13.97 group during salinity acclimation. The liver superoxide dismutase (SOD) activity in the ED‐13.97 group was significantly higher than that in ED‐5.41 and ED‐9.55 groups at the end of salinity acclimation. The muscle malondialdehyde (MDA) content in the ED‐13.97 group was significantly lower than that in the ED‐17.88 group before salinity acclimation and significantly lower than the ED‐5.41 and ED‐17.88 groups on day 7 of acclimation. The results of this study indicate that the rainbow trout in the ED‐13.97 group exhibited optimal salinity acclimation performance.     

土壤中单宁和植酸降解菌的筛选、鉴定及液态发酵研究

为从土壤中筛选能够同时降解单宁和植酸的微生物,本实验利用富集培养技术,分离、筛选、鉴定土壤中的单宁和植酸降解菌,并研究其在液态发酵下的产酶能力。结果显示,从土壤中共获得109株纯菌落,包括39株细菌、46株酵母菌以及24株霉菌。分别用单宁筛选性培养基和植酸筛选性培养基筛选上述菌株,获得27株植酸降解菌和14株单宁降解菌,其中霉菌M-6、M-3和M-1可以同时分解单宁和植酸,且霉菌M-6的水解圈直径大于M-3和M-1。在液态发酵条件下,随着发酵温度的升高(20~35°C),霉菌M-6产单宁酶和植酸酶的活力呈现先升高而后降低的趋势,在发酵温度为30°C时达到最高值(P0.05)。随着发酵p H的升高(p H 4~7),霉菌M-6产单宁酶和植酸酶的活力呈先升高后降低的趋势(P0.05);其中单宁酶活力在发酵p H值为5时达到最高值,显著高于其他处理组(P0.05);而植酸酶活力在发酵p H值为5时达到最高值,显著高于发酵p H 4和7处理组(P0.05),但与发酵p H 6处理组差异不显著(P0.05)。通过菌落和菌株形态学以及分子测序方法,鉴定M-6为黑曲霉。因此,本研究从土壤中分离筛选出3株(M-6、M-3和M-1)能够同时水解单宁和植酸的降解菌,在液态发酵条件下,黑曲霉M-6产单宁酶和植酸酶的最佳发酵温度为30°C,最佳发酵p H值为5。     

Cloning and characterization of fatty acid transport proteins in Japanese seabass Lateolabrax japonicus,and their gene expressions in response to dietary arachidonic acid

In this study, putative cDNA of three fatty acid transport protein (FATP) isoforms, that is FATP1, FATP4 and FATP6, was cloned and characterized from the liver of Japanese seabass (Lateolabrax japonicus), and their expression in response to diets with different arachidonic acid (ARA) levels (0.05%, 0.22%, 0.37%, 0.60%, 1.38% and 2.32% of dry matter) was investigated through a feeding trial. Two subtypes of FATP1, that is FATP1a and FATP1b, were cloned for the first time. The Japanese seabass FATPs showed high identity to their orthologs in other fish species and mammals, but Japanese seabass FATP6 showed low identity to Japanese seabass FATP1 and FATP4. FATP1a gene was highly expressed in brain, liver and eye, whereas FATP1b had the highest gene expression in gill, followed by kidney, skin, eye, muscle and heart. FATP4 gene was primarily expressed in intestine, brain and eye. However, FATP6 had very low gene expression levels in almost all tissues. High levels of dietary ARA (0.60%~2.32%) enhanced the gene expressions of FATP1a and FATP4 in the intestine and the gene expression of FATP1a in the muscle, whereas the dietary ARA supplementation reduced the FATP1b mRNA expression in the liver. The gene expression of FATP1a, FATP4 and FATP6 in the liver, as well as the FATP4 gene expression in the muscle, was not significantly affected by dietary ARA levels. To our knowledge, this is the first study investigating the regulation of FATP gene expressions by dietary ARA.     

Amino acid profiles and amino acid utilization in larval African catfish (Clarias gariepinus): effects of ontogeny and temperature

The present study investigated the qualitative amino acid (AA) requirements of larval African catfish Clarias gariepinus. Yolk-sac larval AA profiles were measured at different temperatures and also in animals reared at 28 °C fed Artemia nauplii or an experimental dry diet. The AA profile of C. gariepinus larvae changed during ontogeny, especially before the start of exogenous feeding. The AA profiles of the food items (yolk, Artemia and the dry diet) differed considerably from that of the larvae. No selective absorption of yolk AA was detected. Higher temperatures led to increased absorption and depletion rates of AA, and also to a higher retention efficiency of yolk nutrients. However, changes in temperature did not induce preferential absorption or depletion of individual AA, and caused only small variations in the AA profile. Depletion rates of individual AAs varied, possibly due to differences between larval and yolk AA profiles, and also to changes in the larval AA profile during ontogeny. There was little regulation of catabolism of individual AA in yolk-sac and starved larvae, and no sparing of essential AA.     

Essential fatty acid requirements of cultured marine fish larvae

Feeding of marine fish larvae is, in most cases, limited to the administration of two species of live prey. This reduction in the range of food available for the cultured larvae may occasionally lead to nutritional imbalances or deficiencies. A large amount of research has been recently devoted to the study of the essential fatty acid requirements of marine fish larvae. Studies on the biochemical composition of developing eggs and larvae, as well as the comparison of the patterns of loss and conservation during starvation, pointed out the importance of n-3 HUFA and arachidonic acid as essential fatty acids for larvae of marine fish. The biochemical composition of marine fish larvae, in terms of lipid content and fatty acid composition of total and polar lipids, is modified by dietary levels of essential fatty acids. Larval growth, survival and activity have also been reported to be affected by dietary levels of essential fatty acids. In addition, some pathological signs, such as hydrops or abnormal pigmentation, have been related to essential fatty acid deficiency in these fish. Based on these effects, the essential fatty acid requirements of marine larval fish have been reported to range between 0.3 and 55 g kg^?1 n-3 HUFA on a dry weight basis, suggesting that quantitative requirements of fish larvae may differ from those of juveniles or adults. But quantitative requirements for larvae of the same species reported by various authors are often contradictory. These differences are discussed in relation to the dietary lipid content, ratio 20:5n-3/22:6n-3 and culture conditions used.     

噁喹酸和氟甲喹在鳗鱼体内的药代动力学研究

研究了单次血管注射喹酸(Oxolinicacid)和氟甲喹(Flumequine)后,在鳗鱼(Muraenesoxcinereus)体内的代谢规律及残留情况。采用高效液相色谱-质谱联用(HPLC-MS)法进行喹酸和氟甲喹的检测,检测低限(LOD)1ng/ml;定量限(LOQ)5ng/ml。喹酸和氟甲喹的代谢过程均可以用一级代谢二室模型来描述,喹酸的分布半衰期:0·18h,消除半衰期:14·84h,总体清除率0·07L/kg·h;氟甲喹的分布半衰期:0·19h,消除半衰期:9·38h,总体清除率0·07L/kg·h。两种药物在鳗鱼体内都有很强的“首过效应”,易在胆汁中积累;给药72h后,喹酸和氟甲喹在可食用组织肌肉中的残留量分别为36·1ng/g和21·8ng/g,低于目前国外要求的最高残留量50ng/g和75ng/g。     

共轭亚油酸及其在动物营养中的应用研究进展

共轭亚油酸(CLA)是亚油酸同分异构体的混合物,CLA多见于反刍动物畜产品中。CLA与人及动物的健康密切相关,CLA在畜产品中的富集对人的许多疑难病症具有深远意义,本文综述了CLA调节动物脂肪代谢和免疫机能,提高生产性能,改善畜产品品质等生物学功能。     

乳酸菌在青贮中的应用及研究进展

青贮饲料是一个复杂的微生物共生体系,主要包括乳酸菌、酵母菌、芽孢杆菌、乙酸菌、梭状芽饱杆菌等,其中以乳酸菌的数量和种类最多,也是在青贮饲料发酵中起主要作用的微生物。着重介绍了乳酸菌微生物青贮剂的种类、选作微生物青贮剂的乳酸菌需符合的条件,阐述了乳酸菌微生物青贮剂的作用机制、添加效果以及影响因素,并对乳酸菌微生物青贮剂近年的研究进展和应用现状进行了总结,指出了乳酸菌微生物青贮剂的未来发展趋势将由单一型向复合型方向发展,同时需将现代基因工程、遗传工程技术引入乳酸菌微生物青贮剂,以开发新型制剂。     

A determination of the quantitative requirements for docosahexaenoic acid for juvenile barramundi (Lates calcarifer)

A series of diets with varying docosahexaenoic acid (DHA; 22:6n‐3) inclusion levels (1 g kg^?1 3 g kg^?1, 6 g kg^?1, 10 g kg^?1, 15 g kg^?1 and 18 g kg^?1) were fed to juvenile barramundi (Lates calcarifer) for 6 weeks. Two additional diets examined the addition of arachidonic acid (ARA; 20:4n‐6) or eicosapentaenoic acid (EPA; 20:5n‐3) to the diets at 10 g kg^?1 when DHA was also included at 10 g kg^?1. Fish were fed the diets on a pair‐fed feeding regime to eliminate feed intake variability. Fish were weighed, and blood and tissue samples were collected after 6 weeks. Behavioural parameters were also assessed. Improvement in growth was seen with increasing inclusion of DHA up to a maximum at 10 g kg^?1 inclusion, albeit the response was minor. However, the addition of ARA to the diet reduced the growth response, while the addition of EPA improved the growth response. An improvement in feeding behaviour was also seen with increasing DHA up to a peak at 10 g kg^?1, while those animals fed diets low in DHA showed increasingly cryptic behaviour. With the increasing inclusion of DHA, a range of pathologies were observed, but the addition of an EPA component to the diet limited these pathologies, while the addition of ARA made little improvement and in some cases exacerbated the pathologies.     

Conjugated linoleic acid affects growth performance,hepatic fatty acid profile and lipid metabolism in juvenile Synechogobius hasta

This study was conducted to determine the effect of dietary CLA (Conjugated linoleic acid) levels on growth performance, fatty acid profiles and lipid metabolism of liver in Synechogobius hasta. Fish were fed six diets with fish oil replaced by 0 (control), 5, 10, 15, 20 and 25 g kg^?1 CLA for 8 weeks. Weight gain, WG, and SGR (specific growth rate) tended to increase when dietary CLA levels increased from 0 to 10 g kg^?1 and then decline with further increasing dietary CLA levels to 25 g kg^?1. FCR (feed conversion ratio) showed contrary trend with WG and SGR. The reduced VSI (vicero somatic index) and increased HSI (hepatosomatic index) were observed in fish fed increasing dietary CLA levels. Whole‐body lipid content declined, but hepatic lipid content increased with increasing dietary CLA levels. Dietary CLA modified total percentages of the main groups of fatty acids in liver. Hepatic 6PGD, ME and ICDH activities increased with increasing dietary CLA levels. FAS and G6PD were very variable and not related to dietary treatments. CPT I activities showed no significant differences among the treatments. Based on second‐order polynomial regression analysis of WG and FCR against dietary CLA level, 8.7–10.1 g kg^?1 was indicated to be the optimal dietary CLA range for maximum growth and feed utilization for S. hasta.     

核酸疫苗的研究进展

传统疫苗是基于抗原刺激机体产生特异性抗体的原理，它们大多数激发机体的体液免疫，很难启动细胞免疫。而核酸疫苗是将外源基因与真核质粒重组后直接导入细胞内，使外源基因在宿主细胞内表达合成保护性抗原蛋白。这是模拟病毒自然感染提呈过程，这既能产生细胞免疫，又能产生体液免疫。本文就核酸疫苗的构成、特点、影响免疫效果的因素、研究进展及其存在的问题和展望作一综述。