中草药方剂对施氏鲟血浆和肝脏中一氧化氮、丙二醛含量及一氧化氮合酶活性的影响

实验采用灌服的方法研究了11种中草药复方制剂对1+龄施氏鲟(Acipenser schrenckii)生长及免疫指标的影响.实验包括6个复方和5个单方中草药添加组,每组设对照.各方剂按通常添加剂的用量对实验鱼灌服,日灌服量为每100g鱼体重灌服0.3ml药液,每日按鱼体重的2%投喂鱼类基础饲料.结果显示:贯众、方剂四、鱼腥草能显著性增加施氏鲟血浆中NO的含量,方剂五、当归、黄芪、茯苓能显著性降低施氏鲟血浆中NO的含量,鱼腥草、黄芪、甘草能显著性降低施氏鲟肝脏中NO的含量;方剂二能显著性增加施氏鲟血浆和组织样中NOS的含量;除黄芪、甘草、茯苓外其他其它中草药方剂均有降低施氏鲟血浆和组织样中MDA含量的作用.     

黄芪、甘草和茯苓对施氏鲟热应激状态下生长及血液生化指标的影响

给体质量为0.09~0.10 kg的1~+龄施氏鲟Acipenser schrencki分别按照0.3g/kg、0.24g/kg和0.3g/kg体质量的剂量每日口灌黄芪Astragalus mongholicus、甘草Glycyrrhiza uralensis或茯苓Poria cocos水煎剂一次,连续给药21d,对照组鱼口灌蒸馏水。停药24h后每组取15尾施氏鲟放入30℃控温水族箱中热刺激2h,然后与22℃正常水温下饲养的施氏鲟一同尾静脉采血,测定施氏鲟的体质量与血清中碱性磷酸酶等酶的活性及总胆红素、甘油三脂等活性物质的含量,研究单方中草药黄芪、甘草或茯苓对施氏鲟生长性能及血液生化指标的影响。结果表明:施氏鲟血清中谷丙转氨酶活性甘草常温组最高[(133.25±64.36)IU/L],对照高温组最低[(68.25±29.33)IU/L];谷草转氨酶活性对照高温组最高[(1 176.67±245.42)IU/L],黄芪常温组与高温组均显著低于对照高温组(P0.05)。这三种中药单方可促进施氏鲟的生长,甘草和茯苓在促进施氏鲟机体代谢方面有一定作用,热应激状态下黄芪保护了鱼体肝肾免受损伤。黄芪催化血清中的尿酸含量显著升高,显示出保护鱼体心血管的作用。     

复方中药对施氏鲟非特异性免疫功能的影响

以施氏鲟（Acipenser schrencki）为实验对象,探讨自组中药方剂（复方A）水煎剂对鲟鱼体内部分非特异性免疫功能指标的影响。将1＋龄施氏鲟随机分为2组,每组3个重复,每个重复20尾鱼。每日按1.1g·kg-1体质量口灌给药,连续7d。给药结束后,每组取10尾鱼高温30℃热刺激2h后,与常温22℃实验组共同采样,测定鱼血浆中蛋白含量、白细胞吞噬及6种组织中溶菌酶活性。结果表明：连续7d口灌复方A有效提高了施氏鲟血浆中总蛋白和球蛋白含量及6种组织中溶菌酶活性,促进了白细胞吞噬作用;在高温应激条件下能调节机体做出快速应激反应,但在高温条件下对部分组织中溶菌酶活性有一定的抑制作用。     

三种中药方剂对施氏鲟抗氧化能力的影响

在水温22℃下,将平均体质量为0.08±0.10 kg的施氏鲟（Acipenser schrenckii）在室内水族箱（0.90 m×0.50 m×0.45 m）中预饲两周后,每日口灌给药一次中药贯众、方剂一和方剂二水煎剂,剂量分别为9、175和36g.50kg-1体质量,口灌蒸馏水为对照组,连续给药14d。然后,取部分鱼高温30℃热刺激2h后,与常温22℃给药的实验组共同采样,测定血液和肝脏内超氧化物歧化酶（SOD）、一氧化氮合酶（NOS）的活性及丙二醛（MDA）和一氧化氮（NO）含量。结果表明,三种中药方剂均能提高施氏鲟抗氧化能力。贯众能有效提高施氏鲟组织中SOD活性,在热刺激情况下,促进鱼体快速应答,降低鱼体内MDA含量,但可能对肝脏造成一定负担,需慎重给药。方剂一能有效降低鱼体内MDA含量,促进机体对热应激做出快速有效应答反应;方剂二抗氧自由基效果较好,受高温热刺激影响不大。     

中草药复方添加剂对施氏鲟生长及血液生化指标的影响

实验研究了7种复方中草药作为饲料添加剂对1+龄施氏鲟(Acipenser schrenckii)生长及血液生化指标的影响.240尾鱼共分为8组.7个复方中草药组和1个对照组,对照组投喂不含中草药添加剂的饲料.结果显示:实验中所采用的几种中药复方均对施氏鲟血浆中的总蛋白、白蛋白、球蛋白含量具有升高的作用.血清中AKP酶活性,除方六外其余中草药添加组的均较对照组有所升高,其中方四及方五升高明显.反映肝功能的指标中,方五可以显著降低LHD在血清中的含量,方二对ALT有显著降低的作用,方一、方四、方五可以显著降低AST在血清中的水平.大部分所选中药方剂对血清中尿素氮(BUN)、肌酐(SCR)、钙、磷含量的影响不显著,方二和方四能显著升高血糖含量;方二、方六和方七还能提高鲟鱼血清铁的水平.研究结果表明这几种方剂具有促进机体代谢功能的作用.     

间断性投喂三种复方中草药对施氏鲟生长及免疫功能的影响

以刺五加、藿香、党参和五味子组成中草药复方一(添加量0.4g/kg);茵陈、大黄、黄芩等组成复方二(0.75g/kg);贯众、大青叶、板蓝根、紫草根等组成复方三(1.86g/kg),水煎剂拌饲。在水温(15.5±1)℃下,将体质量(115±4)g的施氏鲟Acipenser schrencki Brandt饲养于室内半径为1m的圆形水泥池中2.5个月,饲养试验期间每月前15d投喂上述药饵,后15d投喂基础饲料,对照组全程投喂基础饲料,日投喂量为2%,并于试验第16d、46d和76d测定鱼体质量、血清、肝脏、脾脏及头肾中免疫酶的活性,探讨三个中药复方对施氏鲟生长及免疫功能的影响。结果表明:3组中草药均能促进施氏鲟生长,与对照组相比,复方Ⅱ组促进施氏鲟生长显著(P0.05)。实验第16d,复方Ⅰ和Ⅲ组中草药可显著提高施氏鲟头肾中溶菌酶(LZM)、碱性磷酸酶(AKP)和过氧化氢酶(CAT)的活性(P0.05),复方Ⅱ组和Ⅲ组施氏鲟脾脏中AKP及血清中CAT活性显著提高(P0.05);实验第46d,复方Ⅰ和Ⅲ组施氏鲟脾脏和头肾中LZM、AKP和CAT活性、血清中AKP活性及复方Ⅰ组肝脏中AKP活性显著提高(P0.05);实验第76d,复方Ⅰ和Ⅱ组施氏鲟肝脏中AKP活性和脾脏中LZM活性及复方Ⅱ组施氏鲟脾脏中CAT活性显著提高(P0.05)。综合比较,中草药复方Ⅱ在间断性给药方式下提高施氏鲟生长及免疫能力的效果较好。     

饲料中添加姜黄素对杂交鲟幼鱼代谢酶、抗氧化和肠道结构的影响

为评价饲料中添加不同水平的姜黄素对杂交鲟(Acipenserbaeri♂×Acipenserschrenckii♀)幼鱼生长和形体指标、血清生化、代谢酶活性、抗氧化功能和肠道结构的影响,在基础饲料中分别添加0、0.025 g/kg、0.05 g/kg、0.1 g/kg和0.2 g/kg的姜黄素配制成5种饲料,投喂初始体重(16.24±0.11) g的杂交鲟幼鱼。实验分为5组,每组3个重复,每个重复20尾鱼。结果显示:饲料中添加姜黄素对杂交鲟幼鱼生长没有产生显著影响。血清总胆固醇(TG)含量在姜黄素添加量为0.2 g/kg时显著降低(P<0.05)。肝谷丙转氨酶(ALT)活性在0.05 g/kg姜黄素组明显降低,谷草转氨酶(AST)活性在0.05 g/kg、0.1 g/kg、0.2 g/kg添加量时活性显著降低(P<0.05)。十二指肠蛋白酶和淀粉酶分别在0.05g/kg和0.1g/kg姜黄素组活性显著升高(P<0.05)。血清丙二醛(MDA)含量在0.025g/kg时显著降低(P<0.05),过氧化氢酶(CAT)活性在0.025g/kg时显著高于对照组(P<...     

诺氟沙星在西伯利亚鲟体内蓄积规律及其对组织的病理损伤

为了确定诺氟沙星在鲟养殖中的科学使用方法,对不同剂量、不同给药次数情况下诺氟沙星在西伯利亚鲟(Acipenser baerii)体内蓄积规律及毒性进行了研究。分别以0、30 mg/kg、50 mg/kg、100 mg/kg的剂量对西伯利亚鲟连续口灌诺氟沙星3~5 d,每天1次,并于停药后24 h及240 h采集实验鱼血、肝、肾及软骨组织,对4种组织中药物蓄积量进行测定,并对肝、肾和软骨组织进行切片观察。实验结果表明:随着给药剂量增加、给药次数增多,实验鱼4种组织中诺氟沙星浓度逐渐升高,浓度由高到低依次为为:肾、软骨、肝、血清,且血清中药物浓度远远低于另外3种组织。相同给药剂量、不同给药次数时血清中药物浓度无显著差异;而肝、肾和软骨中均差异显著,停药240 h后,显著性消失。切片结果表明,50 mg/kg剂量连续给药5 d后,实验鲟肝、肾组织开始结构损伤变化,100 mg/kg剂量连续给药3~5 d后,损伤情况持续加重,停药240 h后,肝组织损伤情况有逐渐恢复趋势,而肾组织未见明显恢复趋势;而100 mg/kg连续给药3~5 d后,软骨组织出现软骨膜内层细胞减少;停药240 h后有恢复趋势。研究结果表明,诺氟沙星在鲟中使用剂量应小于50 mg/kg,连续给药次数低于5次,以避免对鲟肝组织造成损伤,引起肾不可逆损伤及影响软骨细胞发育和再生,对软骨组织造成潜在影响。     

盐酸氯苯胍在眼斑拟石首鱼体内的药代动力学和残留消除规律研究

在水温(28±2)℃、盐度28条件下,采用30mg/kg的剂量口灌法,用HPLC-MS/MS检测研究了盐酸氯苯胍在体质量为(350.15±5.18)g的眼斑拟石首鱼体内的药代动力学和残留消除规律。结果显示,单剂量口灌给药后,眼斑拟石首鱼血浆中盐酸氯苯胍的药时数据符合一级吸收二室模型,药物在血浆中的达峰时间、血药质量浓度峰值、药时曲线下面积和消除半衰期分别为2.39h、958.78μg/L、33 247.57μg/(L·h)和19.24h;盐酸氯苯胍在肌肉、肝脏和肾脏的血药含量峰值分别为156.72、227.68μg/kg和553.44μg/kg,达峰时间分别为2.0、1.5、2.0h;药时曲线下面积分别4664.04、4897.74、17 228.19μg/(kg·h);消除半衰期分别为19.68、24.33、22.81h。按30mg/kg剂量连续5d口灌给药后,鱼血浆、肌肉、肝脏、肾脏中的药物消除半衰期(t1/2)分别为24.46、35.39、39.60、33.94h。若以10μg/kg为最高残留限量,肌肉作为食用靶组织,在本试验条件下,建议休药期不少于7d。     

饲料中甲基睾酮含量对阿里雌鱼生长及体色的影响

为探明甲基睾酮对阿里雌鱼生长及体色的影响,在水温22～24℃下,将初始体质量(5.78±1.05)g的阿里雌鱼450尾随机分为5组,每组3个平行,每个平行30尾,饲养于75 cm×60 cm×28 cm水族缸中,分别投喂含甲基睾酮0、4、8、12、16 mg/kg 5个梯度的饲料,观察8周增色时间和4周停药期鱼的生长及...     

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.     

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.     

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.