鱼类免疫系统的研究进展

介绍了构成鱼类免疫系统的 3大组成部分———免疫组织和器官、免疫细胞、体液免疫因子 ,分析了它们在鱼类行使免疫防御功能时所起的作用     

鱼类脂肪酸β-氧化研究进展

脂肪酸β-氧化是动物脂肪酸分解代谢的主要途径,在动物生理活动的能量供应和代谢内稳态的维持方面具有举足轻重的作用。在哺乳动物中,关于脂肪酸β-氧化的研究已有大量报道,但是在鱼类中,脂肪酸β-氧化研究相对较少。随着水产养殖业对提高饲料脂肪分解供能和降低鱼体脂肪的要求日益迫切,鱼类脂肪酸β-氧化反应及其组成和调控体系越来越受到学界和产业界的关注。为此,本文从鱼类脂肪酸β-氧化体系组成和关键酶系、β-氧化的组织和底物特异性、β-氧化体系调控因子以及鱼类脂肪酸β-氧化的影响因素等几个方面全面综述了鱼类脂肪酸β-氧化的研究进展,并比较了鱼类脂肪酸β-氧化反应及其组成和调控体系在鱼类与哺乳动物之间,乃至不同鱼种之间的异同,以期为人们更深入地理解鱼类脂代谢与调控体系并开展相关应用研究提供有价值的参考资料。     

低氧胁迫对鱼类影响的研究进展

<正>溶解氧作为水环境中重要的环境因子,是鱼类健康生存的基础。适宜的溶解氧水平能够促进鱼类的生长,对鱼类的繁殖、捕食和运动等产生积极的影响^[1]。低氧胁迫不仅严重制约了鱼类的生长发育,而且会引起鱼类产生应激反应,导致代谢紊乱,严重时导致鱼体死亡^[2]。而经长期演化,鱼类已进化出一系列机制来应对低氧。低氧环境中,鱼类可以通过各种生理反应来抵抗溶解氧的不足,如降低机体能量的消耗、增强氧吸收的能力等,从而应对低氧胁迫^[3]。近年来有关低氧胁迫的研究受到广泛关注,笔者总结了低氧胁迫对鱼类影响的研究进展,为鱼类的健康养殖提供基础资料。     

鱼类脂肪酸结合蛋白研究进展

脂肪酸结合蛋白(FABPs)是一类来自共同祖先基因的小分子蛋白质,相对分子质量为14~16 ku,广泛存在于动物肠道、心脏、脑、脂肪和肌肉等多种组织的细胞内,占细胞内可溶性蛋白总量的1%~8%[1]。研究表明,机体内脂肪酸跨膜运输是被动扩散或由膜蛋白介导的过程,脂肪酸结合蛋白主要结合细胞内游离的脂肪酸(FA)和其他疏水性配体,并将其输送到过氧化物酶体、线粒体和细胞核等细胞器,进而调控脂肪酸氧化和甘油三酯及磷脂合成等脂代谢过程[2](图1)。脂肪酸结合蛋白家族成员的命名是根据其首次分离或鉴定出的组织来命名的,例如肠型脂肪酸结合蛋白(I-FABP)、肝型脂肪酸结合蛋白(L-FABP)等。然而,很多组织中往往有多种脂肪酸结合蛋白基因(fabps基因)同时表达,研究者又对不同的脂肪酸结合蛋白基因按阿拉伯数字命名[3],如fabp1基因(肝型)、fabp2基因(肠型)、fabp3基因(心脏型)等。     

免疫刺激剂对养殖鱼类免疫系统的影响

免疫刺激剂是指能够调节动物免疫系统并激活免疫机能，增强机体对细菌和病毒等传染性病原体抵抗力的一类物质。近年来，国内外均开展了将免疫刺激剂用于水产养殖动物传染性疾病预防的研究，其主要目的是为了将其用于预防使用化学药物难于奏效的水产养殖动物的病毒和细菌性疾病。本文针对养殖鱼类的免疫机制。论述了不同免疫刺激剂对养殖鱼类的作用特点。     

鱼类重要免疫器官抗菌机制的研究进展

正鱼类是重要的水产养殖动物,因其分布范围广,涉及区域多,极易遭受外源压力的影响,故病原菌对鱼类的危害最大。鱼类病原菌多样,致病原因复杂,广泛存在于环境中并易于传播,严重地威胁鱼类养殖业的健康发展~([1])。近年来,随着集约化养殖规模的扩大,病原菌感染导致鱼类大量死亡,限制了产业的发展~([2-3])。因此,一些研究者聚焦于鱼类抗菌的免疫机制探索~([4-6])。免疫系统的响应机制是鱼类抵抗寄生虫、细菌和病毒威胁的防线~([7]),其中,重要免疫器官的抗菌机制探讨是鱼类免疫学研究的核心。     

鱼类低氧胁迫及营养调控和应对研究进展

溶解氧(dissolved oxygen,DO)是影响鱼类生存和生长的重要环境因子,鱼类具有一定的适应溶解氧波动的能力,但长期的低氧胁迫则会导致鱼类生理状态和器官形态结构变化,给鱼类造成损伤甚至死亡。低氧胁迫已成为鱼类主要的环境胁迫因素之一:养殖水体低氧是影响养殖生产品质安全的重要因素;近海海域水环境的低氧是阻碍水生生态系统稳定的关键因素;此外,鱼类长距离保活运输过程中也经常会面临低氧胁迫。分别从低氧胁迫对鱼类行为、生长、繁育和生理影响以及基因表达调控对低氧胁迫的响应(低氧响应的分子机理)等方面的研究进展进行了概述,并总结了目前应对鱼类低氧胁迫的营养调控方案,以期为鱼类低氧胁迫相关研究和探究有效的应激解决方法提供参考。     

鱼类免疫应答机制研究进展

鱼类免疫应答可以分为固有免疫和适应性免疫,但固有免疫发挥主要作用。固有免疫对病原体的识别是通过模式识别受体PRR与病原相关分子模式PAMP的相互结合实现,这与哺乳类相似。但为适应水生生活,鱼类固有免疫对PAMP的识别范围更广,免疫应答的启动条件更低。固有免疫的效应细胞主要是单核/巨噬细胞、嗜中性粒细胞、自然杀伤细胞等,具有吞噬和杀伤功能,还可分泌多种免疫相关的细胞因子,介导发生炎症反应。适应性免疫中,T淋巴细胞通过抗原提呈细胞分解吸收抗原,由主要组织相容性复合物(MHC)类分子递送到细胞表面才能识别。B淋巴细胞分泌产生以免疫球蛋白Ig M为主的抗体分子,而发挥抗体中和作用及免疫调理作用的Ig G在鱼类中比较少见,说明鱼类抗体的免疫功能还处于较低水平。本文综述了近二十年内鱼类免疫应答机制的相关研究进展,为进一步了解鱼类免疫应答机制提供参考。     

鱼类色素细胞及体色调控

介绍了近年来国内外有关鱼类体色方面的研究成果,阐述了色素细胞的种类与形态、鱼类体色变化的内在生理机制以及外部影响因素(包括类胡萝卜素、维生素、光照等),并从基因水平揭示了鱼类体色的形成机制.     

鱼类适应性免疫系统研究概述

正鱼类免疫系统的研究很早,但长期以来,大多集中于先天性免疫系统的研究,对于适应性免疫系统关注较少。作为较为低等的脊椎动物,鱼类虽不具备高等脊椎动物的一些免疫器官,如哺乳类的脊髓和淋巴结,但同高等脊椎动物一样,其免疫系统也由先天性免疫系统和适应性免疫系统共同组成:     

Effects of dietary blend of fish oil with corn oil on growth and non-specific immune responses of grouper, Epinephelus malabaricus

A growth trial was conducted to investigate the effects of fish oil and corn oil on the growth and non‐specific immune responses of juvenile grouper, Epinephelus malabaricus. Five semi‐purified diets were supplemented with 40 g kg⁻¹ of either fish oil (F4), corn oil (C4) or blend of fish oil with corn oil at ratio of 3 : 1 (F3C1); 1 : 1 (F2C2) and 1 : 3 (F1C3). Each diet was fed to triplicate groups of grouper (mean initial weight: 10.26 ± 0.14 g) in a recirculating rearing system for 8 weeks. Weight gain and feed efficiency of fish fed the F4, F3C1 and F2C2 diets were the highest (P < 0.05), followed by fish fed the F1C3 diet, and the lowest in fish fed the C4 diet. Fish fed the C4 diet had a lower survival rate than fish on other dietary treatments. Fatty acid composition of liver and muscle in fish generally reflected the composition of the diet. Leukocyte superoxide anion (O⁻₂) production ratio was the highest in fish fed the F3C1 and F2C2 diets, followed by fish fed the F4 and F1C3 diets, and the lowest in fish fed the C4 diet. Fish fed the F3C1 and F2C2 diets had higher plasma lysozyme activities than fish fed the F4 and C4 diets. Plasma alternative complement activity was higher in fish fed the F3C1, F2C2 and F1C3 diets than fish fed the F4 and C4 diets. These results suggest that grouper fed diets with 3 : 1 or 1 : 1 of fish oil to corn oil ratio had similar growth to the fish fed diet with fish oil. Blend of fish oil with corn oil in diet significantly enhanced non‐specific immune responses of grouper when the fed diet contained fish oil as the only lipid source.     

高不饱和脂肪酸（HUFAs）在淡水鱼类中的营养作用研究进展

鱼粉、鱼油资源的短缺促使全球水产养殖业积极寻找其替代原料,而探究鱼粉、鱼油与其替代物之间的差异尤为重要,其中最主要的差异就是高不饱和脂肪酸(highly unsaturated fatty acids,HUFAs)是否存在及其含量多少。HUFAs是一类碳原子数目≥20、双键数≥3的脂肪酸,具有为动物提供能量、构成细胞膜组分、形成高生物活性物质、调控脂质代谢和免疫功能等重要作用,主要存在于鱼油和某些类别的微藻中。淡水鱼类具备自身合成HUFAs的能力,因此,一般认为HUFAs不是淡水鱼类的必需脂肪酸,无需通过饲料提供。但已有研究指出,饲料中添加一定量的HUFAs能够对淡水鱼类产生积极的营养作用,表明淡水鱼类的脂肪酸营养理论尚需进一步完善。本文综述了HUFAs在淡水鱼类生长、脂质代谢、健康免疫、繁殖特性等方面发挥作用的相关研究结果,明确提出淡水鱼类需要摄取一定水平的外源性HUFAs,指出在当前淡水鱼饲料中普遍使用HUFAs相对缺乏的蛋白源和油脂源的背景之下,HUFAs对淡水鱼类的作用应受到关注。最后,本文对今后淡水鱼类HUFAs营养的研究方向,以及新的HUFAs油脂源的开发前景进行了展望。     

海水鱼类亲体必需脂肪酸营养的研究进展

脂肪酸营养特别是其中的必需脂肪酸在海水鱼类生殖调控方面具有重要的生理作用。饲料中二十碳五烯酸(EPA)、二十二碳六烯酸(DHA)以及花生四烯酸(ARA)含量在调控海水鱼类性腺发育、排卵、孵化率及仔鱼质量等方面作用显著。本文主要从必需脂肪酸需求量、对繁殖性能影响、对机体脂肪酸存储影响及对内分泌调控作用4个方面归纳总结了海水鱼类亲体脂肪酸营养的研究概况,并重点分析探讨了在内分泌调控方面的研究进展,同时对后续的研究重点提出了一些建议。     

海鱼早期阶段必需脂肪酸和磷脂的研究现状与展望

近年来，海鱼早期阶段必需脂肪酸和磷脂研究取得重要进展。本文以从必需脂肪酸的竞争，DHA、EPA和AA的必需性，饲料脂类的种类与含量，以及海鱼的极性脂-磷脂等方面论述海鱼早期阶段必需脂肪酸和磷脂的研究现状与今后方向。     

南海8种低值小杂鱼脂肪含量和脂肪酸组成分析

采用氯仿-甲醇法提取南海盛产的8种低值小杂鱼肌肉、鱼头、内脏中的粗脂肪,利用气相色谱分析其脂肪酸的组成。结果表明,低值小杂鱼头部粗脂肪含量为2.7%～9.7%,内脏粗脂肪含量为2.9%～6.2%,肌肉部分粗脂肪含量为2.0%～8.5%;不同低值小杂鱼的脂肪酸组成基本相同,但其含量有所差异,饱和脂肪酸含量最高,都在40%以上,内脏粗脂肪中的饱和脂肪酸含量较头部和肌肉中的含量高;多不饱和脂肪酸含量差异较大,粗脂肪含量较高的鱼中多不饱和脂肪酸的含量较低;不同鱼种不同部位的粗脂肪中EPA、DHA含量有所差异。蓝圆鲹的头部粗脂肪中DHA和EPA最高,含量达到28.4%,而双带海鲱鲤内脏粗脂肪中的EPA和DHA含量仅为7.26%。     

冬夏两季五种经济鱼类组织脂肪酸含量及组成分析

为了解不同季节不同鱼类不同组织中的不同脂肪酸含量,科学地指导鱼类膳食消费,本实验研究了冬夏两季,采集自上海市场常见的5种经济鱼类:大黄鱼(海洋肉食性),银鲳(海洋杂食性),日本鳗鲡(淡水肉食性),莫桑比克罗非鱼(淡水杂食性),草鱼(淡水草食性),分别检测鱼背部肌肉、腹部肌肉、尾部肌肉、肝脏和腹腔脂肪组织的脂肪含量和脂肪酸绝对含量。结果显示,5种鱼肌肉脂肪酸谱存在显著差异,并与各自的生活环境及食性均有关系;在鱼的腹腔脂肪或肝脏中,饱和脂肪酸(SFAs)和单不饱和脂肪酸(MUFAs)含量较高,且与组织脂肪含量密切相关;而多不饱和脂肪酸(PUFAs)、n-3系多不饱和脂肪酸(n-3 PUFAs)和n-6系多不饱和脂肪酸(n-6 PUFAs)含量较低,且与组织脂肪含量关系不大;大黄鱼和银鲳各肌肉组织中的n-3 PUFAs、二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)含量以及n-3/n-6值高于莫桑比克罗非鱼和草鱼,并与组织脂肪含量呈正相关;冬季草鱼腹部肌肉、莫桑比克罗非鱼尾部肌肉以及日本鳗鲡和银鲳的肝脏中的n-3 PUFAs含量较夏季高。研究表明,脂肪酸组成与物种、食性、水域环境以及季节温度和组织部位均有关系。从补充n-3 PUFAs摄入的角度分析,日本鳗鲡、大黄鱼和银鲳营养价值高于莫桑比克罗非鱼和草鱼,冬季鱼类的营养价值高于夏季。     

Essential fatty acids in Atlantic salmon: time course of changes in fatty acid composition of liver, blood and carcass induced by a diet deficient in n-3 and n-6 fatty acids

Atlantic salmon fry (4 g) were fed a semi-synthetic diet devoid of n-3 and n-6 polyunsaturated fatty acids (PUFA) for 4 months. External signs of nutritional imbalance during the period were slow growth rate and increased mortality. Some symptoms of essential fatty acid deficiency appeared in the fatty acid composition of the blood and liver during the fourth month. At that time, the percentages of n-3 and n-6 PUFA of triacylglycerols (TAG) were nearly exhausted, and the percentages of 22:6 n-3 and of 20:5 n-3 in phospholipids (PL) showed a marked decrease. This decrease in the PUFA level of the PL was paralleled by the appearance of 20:3 n-9, whereas in the TAG an increase in the percentage of 18:1 n-9 was observed. After 4 months the monounsaturated fatty acid 18:1 n-9 constituted nearly 50% of the fatty acids in the TAG fraction of the liver. The time course of the changes in fatty acid composition of liver and blood lipids was quite similar, whereas the carcass lipid composition appeared to respond slowly to a diet devoid of essential fatty acids.     

四种石磺的脂质及脂肪酸组成分析

为比较分析紫色疣石磺、瘤背石磺、里氏拟石磺和平疣桑椹石磺4种石磺科贝类的脂质和脂肪酸组成,实验采用气相色谱/质谱法对4种石磺的脂肪酸组成进行分析研究。结果显示:1 4种石磺科贝类肌肉组织总脂(TL)主要由磷脂(PL)、游离脂肪酸(FFA)、胆固醇(Cho)和甘油三酯(TG)组成;紫色疣石磺肌肉组织中的PL/TL高达73.12%,显著高于其他3种石磺(P0.05);瘤背石磺肌肉组织中的TG/TL达2.75%,显著高于其他3种石磺(P0.05);紫色疣石磺肌肉组织中的FFA/TL高达19.16%,显著高于其他3种石磺(P0.05);2 4种石磺肌肉组织中的脂肪酸组成较为平衡;瘤背石磺和紫色疣石磺肌肉组织中的总饱和脂肪酸(ΣSFA)含量均达35%以上;总单不饱和脂肪酸(ΣMUFA)含量从大到小的顺序依次是瘤背石磺(20.63%)、紫色疣石磺(20.49%)、里氏拟石磺(19.61%)、平疣桑椹石磺(19.42%);平疣桑椹石磺肌肉组织中的总多不饱和脂肪酸含量(ΣPUFA)达34.25%,显著高于其他3种石磺(P0.05)。4种石磺中的C20∶5n3(EPA)含量均大于C22∶6n3(DHA)的含量。研究表明,4种石磺的脂质和脂肪酸组成存在较大差异,可能与其生存环境以及生活习性的差异有关,4种石磺的肌肉组织具有较高的脂类营养价值。其中,紫色疣石磺和瘤背石磺含有丰富的人体必需脂肪酸,且营养均衡,适宜食用;里氏拟石磺具有特殊生理活性的脂肪酸成分含量较高。     

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.     

Essential fatty acids in Atlantic salmon: effects of increasing dietary doses of n-6 and n-3 fatty acids on growth, survival and fatty acid composition of liver, blood and carcass

Atlantic salmon fry (4 g) were fed for 4 months on semi-synthetic diets containing fatty acid methyl esters of either 18:2 n-6, 18:3 n-3 or a mixture of equal amounts of 20:5 n-3 and 22:6 n-3. The different amounts of polyunsaturated fatty acids added were 0, 0.1, 0.2, 0.5, 1 and 2% (by dry weight). Increasing levels of dietary n-3 fatty acids up to 1% gave faster growth rates in salmon fry, and fish fed the mixture of 20:5 n-3 and 22:6 n-3 seemed to grow faster than fish fed only 18:3 n-3. No significant effect on growth rate was seen when the dietary level of 18:2 n-6 was increased. Dietary inclusions of n-3 fatty acids reduced the mortality of salmon, while dietary 18:2 n-6 had no such beneficial effects.
The dietary treatments caused substantial changes in the fatty acid composition of blood and liver phospholipids (PL), whereas the total lipid fraction of the carcass was less affected. Increasing doses of 18:2 n-6 in the diet resulted in an increased percentage of 20:4 n-6 in liver and blood PLs, while the percentage of 20:3 n-9 decreased. The percentage of 18:2 n-6 also increased in liver, blood and carcass. Dietary 18:3 n-3 resulted in increased percentages of 18:3 n-3 and 20:5 n-3 in liver PLs, while the percentage of 20:3 n-9 decreased. There was, however, no significant increase in the percentage of 22:6 n-3. Dietary 18:3 n-3 produced no significant changes in the composition of blood fatty acids, but increased the percentage of 18:3 n-3 in the carcass. The dietary combination of the n-3 fatty acids 20:5 and 22:6 resulted in an increased percentage of 22:6 n-3 in blood and liver lipids and a decreased percentage of 20:3 n-9, but there were no changes in the percentage of 20:5 n-3.