皱纹盘鲍蛋白酶的研究

利用分光光度计比色法测定了２－３ｃｍ的皱纹盘鲍的蛋白消化酶的最适温度、最适ＰＨ以及１１种金属离子对其的影响。结果表明：在最适温度５０℃下的活化能为４．８９×１０×４Ｊ／ｍｏｌ；最适ＰＨ为２．６０和５．００。对其最适ＰＨ值的分析表明：皱纹盘鲍存在有胃蛋白酶，且活性颇高。     

皱纹盘鲍内脏酶的酶学性质及褐藻胶裂解酶的分离纯化

采用(NH4)2SO4分段盐析、透析、阴离子(DEAE-52)交换柱层析、SephadexG-200凝胶柱层析等分离纯化技术，通过SDS-PAGE电泳分析了皱纹盘鲍内脏酶的组成，结果表明鲍内脏酶主要含有两种褐藻胶裂解酶Ⅰ, Ⅱ，一种纤维素酶，一种琼脂酶。对酶的酶学性质分析结果表明两种褐藻胶裂解酶Ⅰ, Ⅱ的最适pH分别为8.6, 7.2，最适温度为35 ℃，分子量分别为35.2 ku, 67 ku；两种褐藻胶裂解酶的热稳定性比较差，且易受金属离子影响；纤维素酶的最适pH为5.0，最适温度为40 ℃。并确定了皱纹盘鲍内脏酶分离纯化的方法及参数，为进一步研究鲍内脏复合酶的性能提供了基础参数。图14表3参12 关键词：皱纹盘鲍； 褐藻胶裂解酶； 纤维素酶； 纯化 E-mail：wqk320@dlfu.edu.cn     

Cd2+、Hg2+、Pb2+抑制罗非鱼EOG反应的研究

将不同浓度Ｃｄ２＋、Ｈｇ２＋、Ｐｂ２＋液分别灌注罗非鱼嗅觉器官,研究其对ＥＯＧ反应的影响。结果表明,这３种离子对ＥＯＧ反应均呈抑制效应,抑制作用的大小与金属离子的种类及浓度有关,Ｃｄ２＋、Ｈｇ２＋、Ｐｂ２＋有效ＩＣ５０分别为３３．９１、６７．７３、１９１．４４μｇ／Ｌ;毒性顺序为：Ｃｄ２＋＞Ｈｇ２＋＞Ｐｂ２＋。     

皱纹盘鲍消化酶的研究

本文对人工养殖的、不同生长时期的正常鲍和病鲍的消化酶活力进行了研究。酶学分析表明，在皱纹盘鲍消化器官中存在着胃蛋白酶（酸性蛋白酶），最适ＰＨ２．８～３．５；类胰蛋白酶（碱性蛋白酶），最适ＰＨ７．８～１０；淀粉酶和纤维素酶。蛋白酶及纤维素酶随着鲍鱼的生长发育活性逐渐增强，淀粉酶逐渐减弱。肝中的酶活性高于其它器官，正常个体酶活性远高于患病个体。我们还做了酯酶的聚丙烯酰胺电泳研究。     

皱纹盘鲍养殖中几个问题的探讨

皱纹盘鲍养殖中几个问题的探讨刘亚军（辽宁省海洋渔业开发中心大连１ｌ６０１３）关键词：皱纹盘鲍，养殖，饵料皱纹盘鲍（Ｈ．ｄｉｓｃｕｓｈａｎｎａｉＺｎｏ）是一种经济价值很高的海产贝类。国内从育苗到养成已形成一定规模，网笼养鲍法正在推广，产量有逐年上升的趋...     

关于玛瑙鲍的探索与研究

选择皱纹盘鲍（Ｈａｌｉｏｔｉｓ ｄｉｓｃｕｓ ｈａｎｎａｉ）的变异个体－－贝壳为红色的玛瑙鲍（Ａｇａｔｅ Ａｂａｌｏｎｅ）作亲体,进行人工繁殖的培育。发现在性产物排放诱导率、孵化率、幼虫附着率和稚鲍生长等方面,玛瑙鲍与皱纹盘鲍大致相同。但稚鲍对不良环境（如赤潮）的抗性,玛瑙鲍明显强于皱纹盘鲍,３２ｄ存活率,前者为６３．１％,后者为３４．３％。ＬＤＨ电泳图谱显示,玛瑙鲍内脏组织中ＬＤＨ活性较高,而被     

鲍内脏酶的研究及其应用前景

皱纹盘鲍是我国北方海珍品的主要养殖种类，其特殊的生长习性、营养及药用价值说明它的消化能力强，体内具有活性强的酶。近年来，鲍内脏酶的研究越来越为人们所重视，特别是鲍内脏中的褐藻酸酶、纤维素酶、琼脂酶的研究和应用。本文主要研讨鲍内脏酶的组成、制备法及其应用前景。     

皱纹盘鲍幼鲍溃烂病病原菌的研究

从患有溃烂病的皱纹盘鲍幼鲍体上，分离到一种致病性细菌。经人工感染试验，证实该菌为皱纹盘鲍幼鲍溃烂病的病原菌。显微镜观察该细菌为革兰氏阴性，极生１～３根鞭毛，能运动的杆菌，大小为０．７～０．８×２．３～２．８ｕｍ。经细菌分类试验鉴定，该菌生长最适温度为２０～３０℃，最适ｐＨ值５．５～８．５。该菌在培养基Ｂ上产生蓝色的荧光素。能利用葡萄糖产酸不产气，果糖、Ｄ－半乳糖、甘露糖、木糖、阿拉伯糖、海藻糖发酵反应阳性，不能发酵乳糖、麦芽糖、鼠李糖、蔗糖，可分解山梨醇、肌醇、肌苷。过氧化氢酶、脲酶、氧化酶、及明胶液化反应阳性；能利用柠檬酸，不还原亚硝酸盐，不产生吲哚和硫化氢，ＭＲ和Ｖ．Ｐ．试验阴性。初步鉴定该病原菌为荧光假单胞杆菌。还进行了病原菌药敏试验，该菌对卡那霉素、呋喃唑酮、恶喹酸敏感，这些药物可作为防治该病的首选药。     

几种金属离子对鲢肝胰脏淀粉酶的影响

以鲢的肝胰脏为材料,取组织匀浆上清液作为酶液进行研究.结果表明:鲢肝胰脏淀粉酶的最适pH为6.8,最适温度为35℃,最适底物浓度为0.03%.进一步研究1、2价金属离子和重金属离子对鲢肝胰脏淀粉酶活力的影响,结果表明:1价金属离子K+、Na+对酶活力没有影响,2价金属离子Ba2+、Ca2+对酶活力具有抑制作用,重金属离子Cd2+、Hg2+对酶活力具有显著的抑制作用.     

用流式细胞仪检测活体鲍倍性

分别取皱纹盘鲍（Ｈａｌｉｏｔｉｓ ｄｉｓｃｕｓ ｈａｎｎａｉ）足肌和血液制样，经ＤＡＰＩ染色后，用ＰａｒｔｅｃＰＡＳ－Ⅲ型流式细胞仪测定其倍性，试验证明三倍体鲍的ＤＮＡ相对含量是二保体的１．５倍，切足法和抽取血液法两种制样方法均得到满意结果，用流式细胞仪法检测鲍倍性适应鲍多倍体产业化的需要。     

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.     

Production of diatom–bacteria biofilm isolated from Seriola lalandi cultures for aquaculture application

Controlled incorporation of selected microalgae and bacteria in aquaculture systems can be beneficial because they can act as microbiological control. That is why the characteristics of biofilm generated naturally in Seriola lalandi culture cages were analysed, their potential benefit to the growth of larvae was studied, and their controlled use for improving the larval viability and as a vector to improve incorporation of previously studied probiotic bacteria was tested. According to biodiversity results, these biofilms are composed of a diatom–bacteria mix showing a decrease in biodiversity in laboratory culture conditions being dominated by Navicula phyllepta and bacteria of the family Rhodobacteraceae. This can be produced on mesh substrates incorporated in bioreactors with rapid growth rate and adhesiveness. Preliminary results from the addition of substrates with this specific biofilm in larvae culture systems showed that it is consumed by the larvae without negative effects, while positive effects on the viability of larvae in combination with probiotics were observed. Considering preliminary results, the addition of these specific substrates with diatom–bacteria biofilms could be a good improvement for aquaculture systems and together with the use of probiotics can contribute to maintaining a stable and controlled system improving the viability of the larval fish culture in its early stages.