海洋鱼类和甲壳类抗菌肽的研究进展与应用前景

抗菌肽的发现与研究已有几十年的历史,抗菌肽是一类生物体中普遍存在并具有广谱抗微生物活性的小分子多肽,被科学家誉为"天然抗生素"。海洋动物抗菌肽是鱼、虾、蟹、贝等海洋动物的非特异性免疫防御系统的重要组成部分,在海洋环境中对于防御外源病原菌的入侵起到重要作用。海洋抗菌肽的研发与应用,不仅具有重要的医学开发价值,也是减少抗生素污染、实现海水健康养殖的重要保障。本文主要以鱼类抗菌肽和甲壳类抗菌肽为例,从抗菌肽的来源与分类、结构特点以及生物学活性等方面,简要概述近年来海洋鱼类和甲壳类抗菌肽的一些研究进展及其开发利用前景。     

抗菌肽在生猪防治上的应用

抗菌肽指由动物体产生的一类具有抗菌活性的碱性多肽物质,很多细菌的代谢产物中也含有抗菌肽。它的主要作用是广谱抗菌,不产生耐药性,调节和修复动物机体的免疫系统,提高动物的免疫力和抵抗力。抗茵肽作为抗生素替代品被应用在养殖业,特别是养猪业上,抗菌肽可以提高保育仔猪的抗病力,调节仔猪肠道微生态平衡、促进营养物质消化吸收、提高饲料利用率等作用。     

水产动物抗菌肽研究进展

抗菌肽是一类广泛存在于自然界生物体内的小分子多肽物质,为机体固有免疫系统的重要组成部分,对革兰氏阴性菌、革兰氏阳性菌、真菌、病毒和寄生虫等均具有较好的抑制或杀伤作用。抗菌肽具有无污染、无残留、广谱抗菌及不易产生耐药性等特点,有望代替抗生素用于水产动物病原性疾病的防控。近年来,抗菌肽已在水生甲壳动物、水产软体动物、鱼类和两栖类等水产动物中得到报道,但其分类和作用机制有待深入研究。本文对不同水产动物中的抗菌肽进行了分类,对各类抗菌肽的结构特征和功能进行了分析,并从直接杀伤作用、非膜靶向作用和免疫调节作用等三个方面对抗菌肽的免疫作用机制进行了分析,期望能够为今后在水产动物中开展抗菌肽的相关研究和应用提供一定的理论支持。     

抗菌肽及其在水生动物中的研究现状

面对滥用抗生素所带来的诸多负面影响,抗菌肽以其独特的抗菌机制、广谱、高效的抗菌活性以及靶菌株难以产生抗性等优点而有望成为抗生素的替代品。水产动物抗菌肽是其自身先天免疫的重要组成部分,对抗菌肽的深入研究有望通过充分调动开发动物自身的防御潜力达到抗病的目的,是实现养殖业可持续发展的重要方向。综述了水生动物抗菌肽的类型、结构及抗菌机制,分析了抗菌肽研究中存在问题,并展望其应用前景。     

传统抗生素替代物抗菌肽在水产养殖中的应用前景

抗菌肽(antibacterial peptides)是具有抗菌活性基因编码的一类短肽,目前发现抗菌肽或类似抗菌肽的小分子肽类广泛存在于昆虫、两栖类、水产动物及哺乳动物中,这种内源性抗菌肽经诱导而合成,在机体抵抗病原的入侵方面起着重要的作用,更被认为是缺乏特异性免疫功能生物的重要防御成分.该文系统介绍了抗菌肽的定义、结构、作用机理、与传统抗生素的差异以及在水产养殖中的应用前景,以期为抗菌肽进一步深入研究提供参考.     

动物抗菌肽饲料添加剂的应用与展望

动物抗菌肽是动物机体内一种小分子肽,具有较好的广谱抗菌作用,并兼具抗病毒、抗肿瘤等生物活性,同时作为一种高效安全的绿色添加剂,对畜禽的生长性能有促进作用,有望成为抗生素的替代品。     

抗菌肽与鱼类肠道健康研究进展

我国是水产养殖大国,随着高密度、集约化养殖模式的发展,养殖中各种病害频繁发生,大量甚至提前使用抗生素进行病害预防相当普遍,抗生素的残留及耐药性对我国水产养殖业造成了严重影响。在纷纷寻求抗生素替代物的背景下,抗菌肽具有广谱抗菌性,较抗生素而言具有独特的抗菌机理,养殖过程中使用抗菌肽不易产生耐药性菌株,又具有提高鱼类等水生动物的生产性能及非特异性免疫功能等作用,正逐渐成为替代抗生素的新型抗菌药物而用于水产养殖中。目前有关抗菌肽在水产养殖上的应用研究主要集中在鱼类等水生动物自身产生的抗菌肽以及作为饲料添加剂的外源性抗菌肽。外源抗菌肽经摄食途径进入肠道,改善鱼类肠道的肠绒毛、肠皱襞高度及肌层厚层等组织形态结构,促进消化吸收功能;调节肠道菌群结构,在杀灭肠道有害微生物的同时增加益生菌含量,改善肠道微环境;在提高肠道消化酶活性和抗氧化能力等方面保障鱼类的肠道健康,同时提高鱼类生产性能、改善其品质、增强鱼体抗氧化和免疫功能[1-3]。笔者着重从水产养殖中抗菌肽饲料添加剂的来源及其与肠道菌群、肠道组织结构、肠道消化功能等相关研究进行总结分析,探讨存在的问题和对策,为抗菌肽在水产养殖中的应用,特别是保护鱼类肠道健康提供参考。     

再谈抗菌肽及其在水产养殖上的应用(上)

正随着我国水产养殖业快速发展,各种疾病频频发生,抗生素大量使用甚至滥用的情况也日趋严重,寻找抗生素的替代物已迫在眉睫。而抗菌肽作为一种新型的高效抗菌药物,由于其具有分子量小、水溶性好、抗菌谱广且作用机制特别、不易产生耐药性等优点,成为新型抗生素开发的良好候选资源。鱼类抗菌肽的研究不仅加深了人     

张超峰:我们都在宣传健康养殖的理念

抗菌肽作为替代抗生素的“新秀”．近年来在动物养殖、饲料加工、疾病防控等领域成了高频词。深圳市圣西马生物技术有限公司是国内专业生产抗菌肽的高新技术企业．也是全球最早将抗菌肽技术应用于畜牧养殖业的企业．近期也在致力于从事水产动物专用抗菌肽方面的研究及产品开发。近日。圣西马高级工程师、市场部经理张超峰先生在接受本刊专访时。诠释了圣西马健康养殖的理念。     

中草药对弧菌病治疗效果的初步研究

<正>弧菌病是水产养殖动物,特别是水产鱼类的常见疾病,严重影响了水产养殖业的发展。目前,控制水产动物弧菌病的主要方式是应用抗生素,然而抗生素能够产生药物残留,其耐药性对生态环境造成污染并能影响食用者的身体健康,已逐步表现出了阻碍水产养殖业可持续发展的作用。中草药因其不易产生耐药性、天然环保、无残留等优点,日益被作为"绿色药品"广泛应用于水产动物养殖。本研究选取11种中     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.