海萝凝集素的分离纯化及性质

海萝(Gloiopeltis furcata)经PBS缓冲液抽提、硫酸铵分级、DEAE-52纤维素离子交换层析和SephadexG-200分子筛层析，从中纯化出海萝凝集素(GFL)，在PAGE和等电聚焦电泳上各显示单一蛋白染色带，其等电点为9．0。用SephadexG-200分子筛层析测得其相对分子质量为8318。海萝凝集素除对人血型红细胞无凝集活性外，对单胞藻及兔、鲤、鲫的红细胞均表现出一定程度的凝集活性，对兔红细胞的凝集活性最强，且不被已测试的D-果糖、D-半乳糖、葡萄糖、蔗糖、乳糖所抑制，而被D-甘露糖、牛甲状腺球蛋白、鸡卵白蛋白、γ-球蛋抑制。该凝集素在pH4．0～10．2均有活性，而在pH6．5～9．1时活性较高。该凝集素在90℃加热1h，活力并未减弱，说明这种凝集素具有很强的耐热性。     

日本沼虾血清凝集素特性研究

取日本沼虾血淋巴液,利用血凝实验和糖抑制实验测定其血清凝集素的凝血活性和糖专一性,对血清凝集素热稳定性、pH值、盐度、重金属离子、EDTA-Na2、有机磷农药、黄酮和多糖类物质对其活性的影响进行了探讨。结果显示:日本沼虾血清凝集素可以对兔、鸡、小鼠、蟾蜍和鲢鱼5种动物血红细胞产生凝集反应,以对小鼠和鸡血红细胞的凝集效价较高。能够专一性结合D-葡萄糖,D-果糖而产生抑制效果。在50~60℃范围内凝集活性最强,80℃及以上凝集素发生变性,无凝集活性。该凝集素pH值作用范围广泛,在pH值2～12都可以使鸡红细胞发生凝集,pH值3～7范围内凝集效果较好。盐度为13～15时,凝集活性最强。凝集素活性能被浓度高于16mmol/L(含16mmol/L)的EDTA-Na2完全抑制,对重金属离子Cu2+和Zn2+敏感性强,其活性被完全抑制。乙酰甲胺磷和敌百虫对日本沼虾血清凝集素活性有一定的影响,黄酮和多糖类物质可显著增强虾血清凝集素的凝集作用。     

4种软体动物凝集素粗提物的凝集活性初探

用人的A、B、O、AB型血和兔、鸡、蛙的共7种血细胞检测4种软体动物凝集素粗制品的凝集活性。结果表明,除缢蛏对人AB型血红细胞,毛蚶对人B型血红细胞不表现凝集活性之外,不同来源的凝集素粗提物对供试血红细胞均有良好的凝集性能。兔血红细胞对各类凝集素最敏感。大多凝集素的pH适应性较广泛。不同凝集素热稳定性不同,缢蛏、毛蚶耐热性较好,80℃处理10min仍能凝集兔血红细胞。不同的糖、金属离子对凝集活性的影响不同,0·02mol/LEDTA可抑制全部凝集素的生物活性。     

绒线藻凝集素的分离纯化及生物活性

将海洋红藻－绒线藻（Dasya villosa）经磷酸盐缓冲液抽提，20%～75%硫酸铵分级沉淀， Sephadex G－200分子筛层析，得到绒线藻凝集素（DVL）。用Sephadex G－200分子筛层析测得其分子量为547 ku。该凝集素凝集兔红细胞的作用不被D-果糖、D-半乳糖、葡萄糖、蔗糖、甘露聚糖、γ-球蛋白所抑制，仅被牛甲状腺球蛋白所抑制，最小抑制浓度为96.88 mg•L-1。2价金属离子Ca2+、Mg2+及EDTA对该凝集素凝集活性没有影响。其凝集活性在25～80 ℃保持不变为28，90～100 ℃加热30 min，活力为27，仍保留50%的活性,说明其具有较强的耐热性。经t检验，注射腹水型肝癌H22肿瘤细胞小鼠在DVL为低（65 mg• kg-1）、中（130 mg•kg-1）高（260 mg•kg-1）剂量时：肝指数、脾指数与生理盐水对照组的均无显著差异；抑瘤率分别为21%、27%、40%，DVL的低、中剂量下抑瘤率与生理盐水对照组的均无显著差异；在高剂量下DVL具有显著的抑制肿瘤细胞生长的作用（P<0.05）。图2表5参21     

军山湖中华绒螯蟹血清凝集素特性分析

从军山湖中华绒螯蟹(Eriocheir sinensis)获得血清,用人A、B、AB、O型红细胞、鸡红细胞及部分细菌菌体检测了血清的凝集活力,同时进行了糖抑制、热稳定性及pH影响试验。结果显示血清能凝集人四种血型红细胞和鸡红细胞,其中对人A型红细胞凝集活力最高;能够和大肠杆菌发生凝集反应,但不能和枯草芽孢杆菌、金黄色葡萄球菌发生凝集反应;凝集条件为pH5.0~5.8、温度4~37℃;1.0%的D-葡萄糖、D-果糖、蔗糖、乳糖、麦芽糖均能不同程度地抑制血清与人A型红细胞的凝集作用。     

中华绒螯蟹血清中外源凝集素的凝集作用及影响因素

中华绒螯蟹血清中的凝集素可凝集人、兔、豚鼠、小白鼠、鹌鹑、鸡、蟾蜍、鳝鱼等动物血细胞,但不凝集鲫鱼血细胞;此外,该凝集素亦可凝集双球菌、蕈状芽孢杆菌、蜡样芽孢杆菌、枯草杆菌等细菌。该凝集素凝集活性可被L-山梨糖、D-果糖、D-半乳糖轻微抑制,并表现出对pH和温度的广泛适应性,在pH为2－12,温度为8℃－64℃范围内均具凝集活性。中华绒螯蟹血清中的凝集素对上述几种动物血细胞的凝集效价高于罗氏沼虾和克螯虾。     

锯缘青蟹血清凝集素的特性和盐析提取研究

对锯缘青蟹(Scylla serrate)血清凝集素的凝集特性进行了研究。结果显示:锯缘青蟹血清凝集素对人、兔、鼠、鸽子、中华鳖、鲫红细胞均有凝集作用,其中对小鼠红细胞凝集活性最强,血凝活性可达29;凝集素活性最适pH 6.0~7.4;盐度对凝集活力有较大影响,NaC l浓度在0.4~0.5 mol/L时基本失活;未纯化血清凝集素对Ca2+、Mg2+未表现出依赖性;凝集素活性能被N-乙酰葡萄糖胺特异性抑制。对青蟹血清凝集素进行硫酸铵分级沉淀分离后,发现凝集素活性主要分布在25%饱和度硫酸铵沉淀区,该组分凝集比活比血清高27.44倍,SDS-PAGE结果表明主要蛋白带型为79 ku、75 ku、72 ku。     

3种海洋贝类凝集素的初步研究

通过用7种红细胞对3种海洋贝类褶牡蛎（Crassostrea plicatula）、缢蛏（Sinonova culaconstricta）和紫贻贝（Mytilus edulis）的凝集素进行凝血活性检测。结果表明：3种贝类凝集素对7种红细胞都有凝集活性，其中紫贻贝的凝集活性最高，家兔红细胞较为敏感。3种贝类凝集素对兔血细胞的凝集活性都可被10种糖不同程度地抑制，亦可被EDTA抑制。3种贝类凝集素在pH=4、pH=5的条件下仍然对兔血细胞显示出较高的凝集活性。缢蛏和紫贻贝的凝集素在80、90℃下处理10分钟，对兔血细胞反而表现出更高的凝集活性，而褶牡蛎的凝集素则在40℃时即丧失活性。     

褶纹冠蚌血清和肌肉凝集素的活性研究

通过血凝试验及糖抑制试验,测定褶纹冠蚌的血清及肌肉提取液的凝血活性及糖抑制专一性,同时进行热稳定性、pH及Ca2+影响试验.结果表明,血清和肌肉凝集素都可以凝集多种脊椎动物的红细胞,其中对鸡红细胞的凝集效价均为最高,分别为25和21;血清和肌肉凝集素都不能凝集大肠杆菌,均能凝集嗜水气单胞菌、枯草杆菌、变形杆菌和保加利亚乳杆菌.血清和肌肉凝集素都有一定的热稳定性,血清凝集素60℃处理10 min丧失凝集活性,而肌肉凝集素50℃处理10 min凝集活性丧失.血清凝集素具有较广泛的pH适应性,在pH 6～10内对鸡红细胞均有凝集活力,而肌肉提取液凝集素在pH＜7或pH＞9时凝集活性消失.血清凝集素能被乳糖和麦芽糖所抑制,肌肉凝集素不能被受试的7种糖所抑制.血清凝集素凝集活性明显地依赖于Ca2+等2价离子,而肌肉凝集素对Ca2+等2价离子没有依赖性.因此,认为褶纹冠蚌血清和肌肉提取液所含凝集素类型不同.用嗜水气单胞菌对褶纹冠蚌进行免疫刺激后,血清和肌肉凝集素对鸡红细胞的凝集效价并没有发生明显变化.     

褶纹冠蚌血清和肌肉凝集素的活性研究

通过血凝试验及糖抑制试验, 测定褶纹冠蚌的血清及肌肉提取液的凝血活性及糖抑制专一性, 同时进行热稳定性、pH 及Ca2+ 影响试验。结果表明, 血清和肌肉凝集素都可以凝集多种脊椎动物的红细胞, 其中对鸡红细胞的凝集效价均为最高, 分别为25和21; 血清和肌肉凝集素都不能凝集大肠杆菌, 均能凝集嗜水气单胞菌、枯草杆菌、变形杆菌和保加利亚乳杆菌。血清和肌肉凝集素都有一定的热稳定性, 血清凝集素60e 处理10 m in丧失凝集活性, 而肌肉凝集素50度处理10min凝集活性丧失。血清凝集素具有较广泛的pH 适应性, 在pH 6~ 10内对鸡红细胞均有凝集力, 而肌肉提取液凝集素在pH < 7或pH > 9 时凝集活性消失。血清凝集素能被乳糖和麦芽糖所抑制, 肌肉凝集素不能被受试的7 种糖所抑制。血清凝集素凝集活性明显地依赖于Ca2+ 等2 价离子, 而肌肉凝集素对C a2+ 等2 价离子没有依赖性。因此, 认为褶纹冠蚌血清和肌肉提取液所含凝集素类型不同。用嗜水气单胞菌对褶纹冠蚌进行免疫刺激后, 血清和肌肉凝集素对鸡红细胞的凝集效价并没有发生明显变化。     

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.