杂色鲍的血细胞

通过光镜、电镜技术,比较了正常状态和受到细菌刺激后杂色鲍血细胞的变化.结果显示,正常状态下的杂色鲍血细胞分为三种类型:颗粒细胞、透明细胞和小细胞;杂色鲍血细胞具有很强的免疫功能,对外界刺激敏感;受到细菌刺激后杂色鲍的血细胞在结构和形态上均发生显著的变化.并推测,颗粒细胞的颗粒中含有大量的水解酶类和抗菌肽等免疫因子,发挥主要的免疫作用.     

皱纹盘鲍血细胞的亚显微结构及分类研究

通过对皱纹盘鲍血细胞的超微结构的观察，将其血细胞分成5种类型：大颗粒细胞、小颗粒细胞、特殊颗粒细胞、透明细胞和淋巴样细胞。根据胞核的形态和胞质中细胞器的结构特征，研究认为大、小颗粒细胞是同一类细胞的不同发育阶段，而特殊细胞则是大、小颗粒细胞的原始细胞；透明细胞和淋巴样细胞是两类完全分化了的细胞。     

几种免疫促进剂对中国对虾血细胞数量、形态结构以及酚氧化酶产量和活性的影响

为了弄清免疫促进剂增强对虾自身免疫力的作用机理，利用脂多糖(LPS)、β-葡聚糖(β-1，3-glucan)、灭活哈维氏弧菌和灭活鳗弧菌对中国对虾血细胞的数量、形态结构以及酚氧化酶(phenoloxidase，PO)的产量与活性在刺激前后的变化进行了研究。研究结果表明，经β-葡聚糖、脂多糖、灭活哈维氏弧菌和灭活鳗弧菌刺激后，中国对虾总血细胞的数量分别增多了83．4％、52．0％、73．4％和111．3％，其中，小颗粒细胞的数量分别增多了100．4％、67．3％、57．2％和102．9％，大颗粒细胞的数量分别增多了47％、10％、127％、和173％；同时，PO的产量分别提高了81．3％、104．7％、29．2％和40．4％，但PO的单位酶活性在刺激前后没有显著变化。透射电镜(TEM)观察结果显示，中国对虾血细胞的超微结构在免疫刺激前后发生了不同程度的变化。在β-葡聚糖和脂多糖刺激下，小颗粒细胞和大颗粒细胞内糙面内质网(RER)和游离核糖体数量明显增多，线粒体数量增加，细胞内分泌颗粒的数量大幅度减少；而透明细胞的超微结构在多糖刺激前后除RER及线粒体数量略有增加、核孔复合体数量明显增加外没有显著差异。经灭活哈维氏弧菌刺激后，对虾大颗粒细胞中RER增生显著并发生泡状化，核质比明显降低；小颗粒细胞中的RER也发生增生且呈泡状化，核质比略有降低；透明细胞中RER数量明显增加，线粒体数量显著增加，核质比明显下降；在灭活鳗弧菌刺激下，对虾透明细胞中游离核糖体和线粒体的数量明显增加，核质比下降；小颗粒细胞内RER的数量明显增多、潴泡体积扩大，细胞质中分泌颗粒的数量比对照组略有减少，核质比明显下降；大颗粒细胞的超微结构除游离核糖体数量有所增加外，变化并不显著。β-葡聚糖和脂多糖主要用于小颗粒细胞和大颗粒细胞；而灭活鳗弧菌和哈维氏弧菌对大颗粒细胞、小颗粒细胞和透明细胞均有作用。     

凡纳滨对虾不同类型血细胞的活性氧水平和酯酶活性

应用流式细胞术(FCM)测定凡纳滨对虾(Litopenaeus vannamei)不同类型血细胞(透明细胞、小颗粒细胞和大颗粒细胞)的非诱导性和诱导性活性氧(ROS)含量以及非特异性酯酶活性,探讨不同类型血细胞的免疫功能.结果显示,透明细胞的非诱导性ROS含量最低,显著低于小颗粒细胞和大颗粒细胞(P＜0.05),大颗粒细胞的非诱导性ROS含量最高;经脂多糖(LPS)刺激后,透明细胞的ROS含量没有显著变化(P＞0.05),小颗粒细胞和大颗粒细胞的ROS含量显著提高(P＜0.05);大颗粒细胞的酯酶活性显著高于小颗粒细胞和透明细胞(P＜0.05).研究表明,3类血细胞在活性氧含量和酯酶活性的功能上存在差异,两类颗粒细胞的活性氧水平较高,大颗粒细胞的酯酶活性较强.     

中华绒螯蟹的血细胞组成、分类及免疫学功能

为了解中华绒螯蟹血细胞组成、分类及其在免疫应答过程中起到的重要作用,本研究通过细胞化学和细胞酶学分析,并结合细胞形态观察,对中华绒螯蟹血细胞的组成、分类进行了研究。同时,通过人工感染嗜水气单胞菌后血液的总血细胞数(THC)和不同类型血细胞数(DHC)的变化,研究不同类型血细胞在免疫应答过程中所发挥的作用。结果显示,依据本实验分类方法,中华绒螯蟹血细胞可以分为4类:大颗粒细胞(G)、中间型颗粒细胞(IG)、小颗粒细胞(SG)和透明细胞(H)。其中小颗粒细胞数量最多,约占33.54%±0.98%,中间型颗粒细胞最少,仅占15.31%±2.01%。4种类型细胞中均含有多糖成分而不含脂质,只有大颗粒细胞在酸性磷酸酶、碱性磷酸酶、β-葡萄糖醛酸酶以及酚氧化酶染色中发现阳性反应。此外,嗜水气单胞菌感染后中华绒螯蟹总血细胞数在3 h后明显升高,在6 h达到峰值,约9.57×106个/m L,并显著高于未处理组和生理组;在感染过程中,大颗粒细胞数量明显下降而透明细胞数量明显上升,这种现象在6 h时达到顶峰并随着时间延长而逐渐恢复至正常水平。研究表明,在中华绒螯蟹非特异性免疫应答过程中,透明细胞主要通过大量增殖执行吞噬功能来参与免疫应答,而大颗粒细胞主要通过裂解释放胞质中所含免疫相关酶参与免疫反应。其中,各类型细胞之间可能存在相互转化作用,而中间型颗粒细胞为这种转化中的过渡类型。     

杂色鲍血细胞中一氧化氮合酶活性的鉴别

一氧化氮合酶(Nitric oxide synthase,NOS)是催化L-精氨酸与O_2产生一氧化氮(Nitric ox- ide,NO)的一种合成酶,它广泛存在于生物体的各个器官和组织中,其活力大小可通过测定NO合成量的多少来决定。NO作为一种新型生物信使分子、效应分子和免疫调节分子,参与机体多种重要的生理病理活动,可以通过非特异性地杀伤细菌、真菌、寄生虫及病毒等。增强机体的非特异性免疫。本文采用生物化学法,以副溶血弧菌和脂多糖为刺激因子.并采用硝酸盐还原酶法测定了NO的水平,对杂色鲍血细胞中的NOS活性进行了初步鉴别。结果表明,加入副溶血弧菌组或LPS组NO水平显著高于对照组(P<0.05),孵育4h后分别为对照组的1.84和1.92倍,孵育8h后分别为对照组的2.38和3.05倍,而且这一反应能被NOS抑制剂L-NAME所阻断,说明杂色鲍血细胞中存在NOS活性。     

锯缘青蟹血细胞的形态及分类

对锯缘青蟹（Scylla serrata）血细胞染色的抗凝剂、染色方法进行筛选。蟹样品体质量约250g。采用亚甲基蓝、瑞氏法染色后，在Olympus油镜下观察、记数、测量，再结合电镜超薄切片观察结果对锯缘青蟹血细胞进行分类。根据血细胞质中颗粒的有无、大小、折光性、染色特性及细胞的大小、核质比等，将锯缘青蟹血细胞分为4种：（1）无颗粒细胞，细胞质中无颗粒；（2）小颗粒细胞，细胞质中有深蓝色小颗粒；（3）中间型细胞，细胞质中既有深蓝色小颗粒，又有折光性红色大颗粒；（4）大颗粒细胞，细胞质中充满了具有折光性的红色大颗粒。4种血细胞的大小顺序从小到大依次为无颗粒细胞、小颗粒细胞、中间型颗粒细胞、大颗粒细胞；核质比则相反，分别为54．01％、37．13％、25．37％、17．49％；其数量百分比分别占20．92％、40．30％、19．39％、19．39％。根据伪足的多少。对4种血细胞在机体的免疫防御机制中所起的不同作用进行了简单探讨。     

杂色鲍与九孔鲍消化酶活力的比较

对人工养殖的、不同体长的杂色鲍与九孔鲍消化酶活力大小进行了研究。酶学分析表明，无论是杂色鲍还是九孔鲍，其纤维素酶随着鲍的体长的增大活性逐渐增强；淀粉酶随着其体长的增大活性逐渐减弱；脂肪酶活性均很小；九孔鲍的纤维素酶活力和淀粉酶活力均大于相同体长的杂色鲍。     

复方中草药对杂色鲍幼鲍血淋巴中几种酶活力的影响

将12种中草药按其不同的药理作用和药效进行配伍，形成5组复方中草药，分别编号为中草药1～5号。将以上中草药添加到杂色鲍幼鲍的人工配合饲料中，连续喂饲幼鲍，饲养47d后，测定幼鲍无细胞血淋巴中超氧化物歧化酶(SOD)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、溶茵酶(LSZ)活力。结果显示，所有添加中草药的sOD活力均比对照组降低，中草药1、5号可提高幼鲍血淋巴的ACP和LSZ活力，而对AKP则起到降低的作用；中草药3、4号可提高幼鲍血淋巴的LSZ活力，却降低幼鲍血淋巴的ACP和AKP活力，中草药2号对ACP、AKP和LSZ活力均有提高作用，具有较突出的促进杂色鲍幼鲍免疫酶活力的功能。     

杂色鲍自然海区人工放养的初步试验

本文报道了杂色鲍标志放养和人工造礁试验的方法和结果．试验表明，杂色鲍的最适放养壳长为2．5—3．0厘米；2龄的杂色鲍，平均壳长为4．8厘米，这一龄段的鲍生长最快，3龄的杂色鲍平均壳长为6．3厘米，最大的个体可达7．0厘米；4龄以后，其生长明显减慢。据此，似可将3—4龄，壳长超过6．0厘米的杂色鲍定为上市规格。此外，本文还对杂色鲍对自然环境的适应、生长、移动，以及人工造礁的方法和效果作了介绍。     

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.