Pirarucu growth under different feeding regimes

In order to assess the most suitable feeding schedule for pirarucu, Arapaima gigas, we placed groups of seven fish in 12 1-m³ cages and investigated various feeding variables in a 2 × 2 factorial design. The feeding variables analyzed were one feeding (OC) or two feedings (TW), feeding daily (1D) or every other day (2D), and their interactions: one feeding once per day (OC/1D), two feedings per day (TW/1D), one feeding every other day (OC/2D) and two feedings every other day (TW/2D). The experiment lasted for 45 days, and the fish were maintained on a commercial extruded diet. The results showed similar final weights between fish maintained on feedings OC and TW, but higher ones in fish fed 1D than 2D. Weight gain was higher when the fish were fed TW and 1D. Apparent feed conversion was not affected in fish fed OC or TW and 1D or 2D. Daily feed consumption was also higher for the feeding schedules of TW and 1D. The combination of feeding schedules produced higher final weights and weight gains for fish fed OC/1D and TW/1D. The apparent feed conversion value was higher only in fish fed TW/1D. Daily feed consumption values were significantly higher in fishes fed TW/1D. The lowest value was recorded for OC/2D.     

Leptin in fish: possible role in sexual maturation in male Atlantic salmon

Leptin plays an important role in energy homeostasis and reproductive function in mammals, while its function in fish is still poorly understood, especially its role in reproduction. In the present study, leptin gene expression and circulating leptin plasma levels were measured during sexual maturation in male Atlantic salmon parr. In maturing male salmon, higher hepatic leptin (lepa1) gene expression levels were observed during mid-spermatogenesis compared to immature fish. An upregulation of leptin during sexual maturation has also been observed in a few other teleost species. The physiological significance of elevated leptin levels during the maturational process in teleosts remains to be explored.     

鳜免疫球蛋白 D 重链基因的克隆与表达分析

用RACE-PCR和RT-PCR方法获得鳜(Siniperca chuatsi)膜结合型免疫球蛋白D(Membrane-bounded IgD,mIgD)重链基因的全长cDNA序列。鳜mIgD的cDNA全长为3358bp,其5l非编码区包含30bp,3l非编码区包含337bp;开放阅读框包含2991bp,编码996个氨基酸,基因结构为VDJ-μ1-δ1-δ2-δ3-δ4-δ5-δ6-δ7-TM。鱼类IgD恒定区氨基酸序列比对结果显示,鳜mIgD存在半胱氨酸和色氨酸保守位点,与其他鱼类IgD的相似性在37%～72%之间。用邻接法(Neighbor Joining)构建的鱼类免疫球蛋白基因的系统发育树表明,鱼类IgD形成独立的一支,鳜mIgD与牙鲆和庸鲽IgD聚为一支。荧光定量PCR结果显示,鳜mIgD的mRNA主要分布于外周血白细胞、胸腺、头肾、中肾和脾脏中。     

Status of the crucian carp, Carassius carassius (L.), in the UK

The crucian carp, Carassius carassius (L.), is a small fish of restricted distribution in the UK, which is probably only native to central and eastern England. The crucian carp is endemic to northern Europe. It has been widely confused with the introduced and congeneric goldfish, Carassius auratus (L.), and forms hybrids with that species and the introduced Cyprinus carpio L. The status of this fish has become confused with the presence of the congener and its hybrids, and it is now thought to be less frequent in occurrence than formerly.     

Ascorbic acid and reproduction in fish: endocrine regulation and gamete quality

High ascorbic acid concentrations have been associated with gonad and brain tissues in teleost fishes. Although a direct dietary effect on gamete quality has been given some attention recently, the mechanism of action of ascorbate along the cascade of reproductive events in the hypothalamus, pituitary and gonads has not been defined. Data relating to gamete production and quality, as well as a possible protective role for ascorbate against cumulative genetic defects during gametogenesis and congenital malformation during gestation (embryonic development) is reviewed. It is suggested that the gonad growth in response to gonadotropin stimulation involves direct interaction between catecholamines and steroid hormones and their receptor sites. This interaction acts as a regulatory mechanism of ascorbate absorption, transfer and metabolism (degradation and/or renewal) in the reproductive system. We conclude that ascorbic acid is a leading nutrient in reproductive tissue functions and further research is needed on: (1) its antioxidant effect on gametes' (sperm and ova) capacity to prevent DNA damage occurring prior to (endogenous) and after spawning (environmental insults); (2) its dietary requirement to optimize survival and physiological recovery in multiple spawners; (3) the integration mechanism of ascorbic acid action as part of the overall endocrine regulation of neurohormonal–hormonal pathway in fish reproduction; and (4) the possible role for ascorbate in regulating fish maturation and/or infertility in the presence of enhanced UV-radiation or conditions of intensive aquaculture (hypoxia, oxygen supersaturation, dietary pro–, and antioxidants).     

斜带石斑鱼IgM、IgZ和IgD重链基因的克隆

应用RACE方法获得斜带石斑鱼膜结合型免疫球蛋白M(membrane-bound immu-noglobulin M,mIgM),膜结合型免疫球蛋白D(mIgD),分泌型免疫球蛋白Z(secretory immu-noglobulin Z,sIgZ)的重链基因。斜带石斑鱼膜结合型IgM重链恒定区包含3个恒定区结构域(μ1,μ2,μ3)以及两个跨膜外显子(TM1,TM2),TM1外显子与μ3结构域末端相连接。氨基酸序列相似性分析结果显示,斜带石斑鱼mIgM各恒定区与牙鲆mIgM恒定区相似性最高,为53%~78%。mIgD的cDNA全长为3 375 bp,开放阅读框包含3 006 bp,其恒定区由1个μ1外显子,7个δ外显子以及跨膜区组成。斜带石斑鱼IgD恒定区与鳜IgD各恒定区氨基酸序列相似性最高,δ1~δ7的相似性分别为75.5%、75.8%、65.4%、76.6%、88.1%、90.6%、82.8%,TM结构域为82.7%。sIgZ的基因结构与其他硬骨鱼类sIgZ的结构相似,包括4个外显子和3个内含子,内含子长度分别为222、129和458 bp。利用半定量PCR分别检测了这3种基因在斜带石斑鱼各器官/组织中的表达,发现mIgM在头肾、肾脏、脑、脾脏、肠、鳃、心脏和胸腺中均有表达;mIgD的mRNA在头肾、肾脏以及胸腺中有较高的表达,在肠中表达量较低;sIgZ mRNA主要分布于淋巴组织如头肾、肾及脾脏中,而在鳃、心脏和胸腺中的丰度较低。     

Nucleotide‐binding and oligomerization domain (NOD)‐like receptors in teleost fish: Current knowledge and future perspectives

Nucleotide‐binding and oligomerization domain (NOD)‐like receptors (NLRs) are a group of intracellular pathogen recognition receptors (PRRs) that play key roles in pathogen recognition and subsequent activation of innate immune signalling pathways. Expressions of several NLR subfamily members, including NOD1, NOD2, NLR‐C3, NLR‐C5 and NLR‐X1 have been reported in many different teleost fish species. These receptors are activated by a variety of ligands, including lipopolysaccharides (LPS), peptidoglycans (PGN) and polyinosinic‐polycytidylic acid [Poly(I:C)]. Synthetic dsRNA and bacterial or viral infections are known to stimulate these receptors both in vitro and in vivo. In this review, we focus on the identification, expression and function of teleost NLRs in response to bacterial or viral pathogens. Additionally, NLR ligand specificity and signalling pathways involved in the recognition of bacterial or viral stimuli are also summarized. This review focuses on current knowledge in this area and provides future perspectives regarding topics in need of additional investigation. Understanding the response of innate immune system to bacterial or viral infections in diverse species could inform the development of more effective therapies and vaccines.     

硬骨鱼免疫相关microRNA研究进展

MicroRNA (miRNA)是一类长度为18～25 nt的非编码RNA,在硬骨鱼免疫应答中起重要作用。近年来,借助高通量测序与荧光定量PCR (RT-PCR)技术,筛选到大量免疫相关的差异表达miRNA (DE miRNA)。通过比较多种硬骨鱼在不同病毒/细菌感染条件的miRNA表达谱,筛选出相同DE miRNA,并认为筛选出的DE miRNA是潜在参与调节宿主免疫应答的进化上保守的候选DE miRNA。据此,我们在病毒感染表达谱中筛选到10个进化保守的DE miRNA,细菌感染表达谱中筛选到8个保守的DE miRNA。此外,miRNA的功能研究也取得较大进展,宿主miRNA不仅可直接抑制病毒的复制,同时参与调控干扰素反应、炎症、细胞凋亡等过程。本文简述了硬骨鱼免疫相关miRNA的研究进展,以期为硬骨鱼疾病预防与治疗提供新思路。     

Partial characterization of the gene encoding myoadenylate deaminase from the teleost fish <Emphasis Type="Italic">Platichthys flesus</Emphasis>

AMP-deaminase (AMPD, EC 3.5.4.6), which catalyzes the irreversible hydrolytic deamination of AMP to IMP and ammonia, is an important energy-related enzyme. The partial genomic sequence of the gene encoding myoadenylate deaminase (AMPD1) from the teleost fish Platichthys flesus was determined. The amino acid sequence of P. flesus AMPD1 shows 82% homology with that of the teleost fish Danio rerio. Comparison of genomic sequences of P. flesus and Rattus norvegicus reveals a high degree of conservation of both sequence and structural organization. A phylogenetic analysis of AMPD sequences shows that bony fish and mammalian AMPD1s arise by duplication of a common primordial gene.     

Responses of circulating arginine vasotocin, isotocin, and melatonin to osmotic and disturbance stress in rainbow trout (Oncorhynchus mykiss)

In teleost fish exposed to stressors AVT has been implicated in activation of the hypothalamo-pituitary-interrenal axis. Mel has been shown to counteract several behavioural and endocrine consequences of stress in mammals. These studies were undertaken to investigate the effects of either disturbance or osmotic stress, applied either separately or simultaneously, on plasma AVT, IT and melatonin in rainbow trout (Oncorhynchus mykiss). Hormones were determined in plasma by high-performance liquid chromatography preceded by solid-phase extraction. The results showed that both forms of stress caused significant increase in plasma AVT concentration, although more pronounced elevation was observed in physically disturbed fish. Conversely, neither osmotic nor disturbance stress affected plasma IT concentration. The apparent difference in response to stress by the two close related neurohypophysial nonapeptides suggests independent mechanisms controlling their synthesis and/or release and supports the idea that only AVT plays a role in physiological response to stress. Plasma Mel level was depressed in fish subjected to disturbance stress and to both stresses applied simultaneously, an effect possibly associated with the elevation of plasma AVT concentration. Results are discussed in relation to physiological interactions between hormones.     

Development of a system for measuring calcitonin in the stingray Dasyatis akajei (a cartilaginous fish): the possible involvement of stingray calcitonin in gonadal development

To elucidate the physiological role of calcitonin (CT) in stingrays (cartilaginous fish), an enzyme-linked immunosorbent assay (ELISA) system using a specific antibody against stingray CT has been developed. Synthetic stingray CT was subcutaneously injected into mice four times—once every 2 weeks—together with an adjuvant. We purified the IgG antibody fraction using the protein A affinity chromatography from collected antiserum. Evaluating the antibody titer, we found the antibody’s optimum dilution ratio to be 600 times. Competitive ELISA has been developed using the antibody diluted 600 times. Our antibody did not cross-react with teleost CTs and muscle extraction, but cross-reacted with stingray plasma and the extract of the ultimobranchial gland, the secretary organ of stingray CT. Using this ELISA, we measured the plasma CT level in stingrays and examined its correlation with several mineral concentrations. Plasma CT did not show significant correlation to calcium, magnesium, inorganic phosphorus, sodium, chlorine, or urea, although there was a correlation among the factors involved in osmoregulation, such as sodium, chlorine, and urea. On the other hand, plasma CT was significantly correlated to body weight and length. Furthermore, there was a significant correlation between plasma CT and gonad weight. Since plasma CT was correlated with the weight of liver, which is involved in the synthesis of egg yolk protein, we examined the influence of 17β-estradiol (E2) on CT secretion. After E2 injection, the plasma CT level increased significantly. This is the first study to demonstrate that E2 induced plasma CT secretion in cartilaginous fish.     

Cloning and characterization of <Emphasis Type="Italic">Bax1</Emphasis> and <Emphasis Type="Italic">Bax2</Emphasis> genes of <Emphasis Type="Italic">Ctenopharyngodon idellus</Emphasis> and evaluation of transcript expression in response to grass carp reovirus infection

Multidomain proapoptotic Bcl-2-associated X (Bax) protein is an essential effector responsible for mitochondrial outer membrane permeabilization, resulting in cell death via apoptosis. In this study, two Bax genes of grass carp (Ctenopharyngodon idellus), designated as CiBax1 and CiBax2, were isolated and analyzed. The obtained CiBax1 cDNA is 2058 bp long, with a 579 bp open reading frame (ORF) coding a protein of 192 amino acid residues. The full-length cDNA of CiBax2 is 1161 bp, with a 618 bp ORF coding 205 amino acids. Both CiBax1 and CiBax2 are typical members of Bcl-2 family containing conserved Bcl and C-terminal domains, and they share conserved synteny with zebrafish Bax genes despite the grass carp Bax mapping to different linkage groups. Phylogenetic analysis showed that CiBax1 was clustered with Bax from most teleost fish, and CiBax2 was close to Bax2 from teleost fish but far separated from that of Salmo salar. Quantitative real-time PCR analysis revealed broad expression of CiBax1 and CiBax2 in tissues from healthy grass carp, but the relative expression level differed. The mRNA expression of CiBax1 and CiBax2 was both upregulated significantly and peaked in all examined tissues at days 5 or 6 post-infection with grass carp reovirus. Subcellular localization indicated that CiBax1 protein was localized in both nucleus and cytosol, while CiBax2 protein only in cytosol. Moreover, CiBax2, but not CiBax1 was colocalized with mitochondrion under normal condition. Taken together, the findings would be helpful for further understanding of the function of Bax in teleost fish.     

卵形鲳鲹TLR13基因的克隆、表达分析和亚细胞定位研究

Toll样受体(Toll-like receptor,TLR)是一种古老的先天性免疫受体,参与病原体相关分子模式识别,对维持免疫稳态和预防感染至关重要。本研究克隆和鉴定了卵形鲳鲹(Trachinotus ovatus)TLR13基因(命名为ToTLR13),其开放阅读框(ORF)为1 269 bp,编码422个氨基酸,等电点为8.13。保守结构域分析显示,ToTLR13含有跨膜结构域(TM)、LRR结构域和TIR结构域,符合TLR家族的典型特征。通过建立TLR13保守域三级结构发现,ToTLR13与小鼠(Mus musculus)和大黄鱼(Larimichthys crocea) TLR13功能结构域的蛋白三级结构具有较高重叠性。多序列比对显示,ToTLR13与其他硬骨鱼TLR13具有较高的相似性,与其他纲物种的序列相似性较低。系统进化树结果显示,To TLR13与硬骨鱼TLR13聚在一起,其中与鞍带石斑鱼(Epinephelus lanceolatus)最为接近,与哺乳动物、两栖类和贝类相分离。实时荧光定量PCR (Real-time fluorescence quantitativ...     

Kisspeptin对鱼类生殖轴的调控机制研究

Kisspeptin(简称Kiss或者Kp)是由KISS1/Kiss1基因编码的一种下丘脑神经肽,通过其受体KissR(也称作GPR54)的介导参与了多种生理过程,如抑制肿瘤转移和参与生殖调控。目前,尽管在鲤形目(Cypriniformes)、鲈形目(Perciforms)、鲽形目(Pleuronectiforms)、鲀形目(Tetraodontiforms)、颌针目(Beloniforms)、鲉形目(Scorpaeniformes)、鲑形目(Salmoniformes)及鳕形目(Gadiformes)等多种鱼类中均鉴定出了kiss/kissr基因,但Kiss/KissR系统在鱼类生殖调控中的精确作用及其分子机制尚未完全阐明。尤其是在鱼类中存在2种kiss及3种kissr基因,Kiss/KissR系统对鱼类生殖调控的作用方式更加复杂。本文简要总结鱼类Kiss及其受体的研究进展,并对Kiss的生理学功能、信号转导机制以及kiss/kissr表达调控研究进行概括讨论,旨在加深对鱼类Kiss/KissR系统的认识和了解,为后续研究指明方向。     

鱼类生殖细胞移植的研究进展及应用前景

生殖细胞移植是指将供体的生殖细胞移植到同种或异种受体体内,供体生殖细胞嵌合到受体性腺,经过增殖、分化并最终发育为功能性配子的过程。作为辅助生殖技术,它不仅为珍稀濒危动物的繁育和保护提供了新途径,同时也为生殖干细胞的功能研究提供了有效手段。鱼类生殖细胞移植研究首先在模式鱼类斑马鱼中开展,经过十多年的发展,取得了一系列突破性的进展:主要包括先后建立了以胚胎、仔鱼和成鱼为受体的生殖细胞移植体系,精原和卵原干细胞的发现拓宽了供体生殖细胞的选择,受体的选择与制备方法的完善。该技术在缩短鱼类性成熟周期、性控育种、珍稀濒危鱼类保护等方面具有巨大的应用前景,已成功在多种淡水和海水鱼类中开展了研究和应用。本文结合作者的研究实践和经验,系统地梳理和总结了鱼类生殖细胞移植的研究进展,指出了该技术实践应用的关键问题,并探讨了其应用前景。     

Evidence for synergism of the antimicrobial peptide piscidin 2 with antiparasitic and antioomycete drugs

Piscidins are potent, broad‐spectrum, host‐produced antimicrobial peptides (AMPs) that appear to constitute the most common AMP family in teleost fish. Here, we show that piscidin 2 has potent activity against the water mould Saprolegnia, one of the most important pathogens of freshwater fish. The minimum oomyceticidal concentration (MOC₁₀₀) of piscidin 2 against zoospores of three pathogenic isolates of Saprolegnia ranged from 12.5 to 25.0 μg mL^?1. This piscidin concentration is well within levels that have been estimated to be present in at least some fish (1–32.5 μg mL^?1). In the presence of either copper or malachite green, two drugs commonly used to treat water moulds, there was evidence for partial synergism (PSYN) with piscidin 2. There was also evidence for PSYN after exposure of the ciliate parasite Tetrahymena pyriformis to piscidin 2 plus copper. Our data provide further evidence that piscidins may be an important host defence against skin and gill pathogens and that the piscidin levels in host tissue might influence the success of drug treatments.     

The nutritional management of barramundi, Lates calcarifer– a review

Barramundi nutrition research has been undertaken since the 1980s. From that time to the present, the requirements for most nutrients, energy demand, ingredient utilization and the effects of nutrition on flesh quality aspects have all been examined to varying extents. Optimal protein content of diets has been shown to vary with diet energy density and also the size of fish that are being fed. Most studies have suggested a protein requirement from 450 to 550 g kg^?1. For small fish, a protein to energy ratio of 25 to 30 g MJ^?1 is suggested. Limited work has been carried out on fish larger than 500 g. The 10 essential amino acids for other fish are also considered to be required by barramundi. Proportional requirements have been identified for methionine, lysine and arginine. Protein utilization efficiency by barramundi has been estimated at 46% efficiency. Iteratively determined protein and amino acid requirements suggest that the requirement for protein and amino acids will decrease with increasing fish size and are largely consistent with empirically determined requirements. Lipid requirements for energy and essential fatty acids (EFAs) show that smaller fish performed the best with a dietary lipid level of 140–160 g kg^?1, while growth of larger fish continued to improve with lipid levels up to 190 g kg^?1, although no higher levels were examined. EFA requirements have been identified for long‐chain n‐3 fatty acids and minimum levels of 10 g kg^?1 have been indicated. An optimal ratio of n‐3 to n‐6 fatty acids of 1.5 to 1.8:1 was also suggested. Barramundi have shown limited capacity to utilize dietary carbohydrates for energy, with starch digestibilities below 30% at even low inclusion levels. Barramundi also exhibit limited glycaemic control, being unable to rapidly reduce blood glucose levels. Requirements have been demonstrated for several key vitamins and quantitative requirements determined for varying forms of ascorbic acid (vitamin C). Quantitative requirements have also been established for pyridoxine and pantothenic acid but only qualitative assessments for other key vitamins. Few mineral requirements have been identified. Phosphorus is the only mineral to be studied and a requirement between 5.5 and 6.5 g kg^?1 is suggested. Energy demands of barramundi have been shown to be largely driven by thermodynamic demands on metabolic requirements and the demand for somatic energy deposition. Energy utilization by barramundi has been estimated as 68% efficient. Energy demands for maintenance are shown to be related to liveweight by an exponent of about 0.8. Variations in temperature are shown to vary the maintenance energy requirement but do not affect the efficiency of energy utilization. Feed management through feed specification selection has been shown to be possible through selection of feed protein and energy content based on the fish's change in somatic energy density. Typically, this leads to the use of lower protein and higher energy density feeds with larger fish. Ration allocation based on changes in fish size and temperatures has been studied from both iterative and empirical perspectives, and tables were developed based on these findings. Several key feed ingredients have been evaluated for their digestibility, palatability and energy and nutrient utilization. Among those ingredients were meat meals, lupin kernel meals, soybean meals and some plant oils. Limited effects of feed ingredients on flesh quality have been noted, although some effects of diet nutrient and energy specifications have been noted.     

酸化剂对草鱼生长和非特异性免疫能力的影响

为考察不同类型酸化剂对草鱼生长及生理机能的影响,在基础饲料(对照组)中分别添加0.21％磷酸、柠檬酸、乳酸和复合酸,饲养初始体重为(10.33±0.03)g草鱼(Ctenopharyngodon idellus)8周.结果表明:(1)与对照组相比,饲料中添加0.21％柠檬酸、乳酸和复合酸均显著提高草鱼的增重率、特定生长...