虾蟹蜕皮周期分期鉴定技术研究进展

<正>甲壳动物中的虾蟹类主要营水生生活,其中大部分种类具有较高的经济价值^[1]。蜕壳又称蜕皮^[2],包括旧表皮的蜕去和新表皮的形成^[3]。蜕皮作为甲壳动物生长发育的标志性特征,其在整个生活史中具有周期性的动态变化^[4],从上一次蜕皮结束到下一次蜕皮结束的时间为一个蜕皮周期^[5]。阐明虾蟹类的蜕皮周期及各期的特征^[6]是解决虾蟹类水产养殖过程中蜕皮不同步、蜕皮失败等问题的重要理论基础。其中,蜕皮分期鉴定技术是研究蜕皮周期极为重要的技术工具。     

中国对虾蜕皮与附肢刚毛发生关系的研究

中国对虾（Ｐｅｎａｅｕｓｃｈｉｎｅｎｓｉｓ）的蜕皮周期具有独特的、可预报的变化之特性。利用这一特性可确定中国对虾的蜕皮分为４个阶段：（１）蜕皮后期（阶段Ａ、Ｂ）：刚蜕皮之后；（２）不蜕皮期（阶段Ｃ１－３）：组织生长和食物贮藏期；（３）蜕皮前期（阶段Ｄ０－３）：为下次蜕皮准备有效的形态和生理变化；（４）蜕皮期（阶段Ｅ）：旧表皮脱落期。     

关于新对虾属Metapenaeus幼体发育分期的探讨

新对虾属Ｍｅｔａｐｅｎａｅｕｓ为对虾科Ｐｅｎａｉｄａｅ中的重要类群，随着养虾业的发展，新对虾越来越受到重视。在人工育苗中，虾类幼体发育分期对指导生产有现实意义。国外学者Ｍ．Ｓ．Ｍｕｔｈｕ等（１９７８）对近缘新对虾和道氏新对虾的糠虾（Ｍｙｓｉｓ）阶段分为５期，并在第Ⅴ期糠虾幼体之后增加两个中间期，形成Ｎ－Ｚ－Ｍ－Ｉ的“６－３－５－２”模式。作者在中型新对虾的幼体变态实验观察中注意到，糠虾幼体在一次蜕皮后其体长和附肢形态均有渐微的变化，这种形态上的细微差异不宜作为分期的依据，幼体分期的主要依据以蜕皮为标志。因此新对虾属的幼体发育分期可借鉴中国对虾（Ｐｎｕａｅｕｓｏｒｉｅｎｔａｌｉｓ）幼体分期模式划分，即Ｎ－Ｚ－Ｍ为“６－３－３”。     

甲壳动物蜕皮相关基因的研究进展

<正>世界上甲壳动物的种类多达约2.6万种,其中虾、蟹等甲壳动物营养丰富,味道鲜美,具有很高的经济价值。甲壳动物通过退去旧的外骨骼,长出新的外骨骼来完成自身的生长。甲壳动物的蜕皮由神经、内分泌系统间的协调作用[1],及外源因子的干扰作用等共同决定蜕皮周期的长短,影响生长发育。甲壳动物的蜕皮受Y器官分泌的蜕皮激素和X器官窦腺复合体分泌的蜕皮抑制激素共同作     

虾蟹类的幼体发育

虾、蟹类属节肢动物门甲壳纲十足目,具有重要的经济价值。这里的幼体是指某些动物在形态上与成体不同的自由生活初期的发育阶段,如桡足类(水蚤)有无节幼体与桡足幼体即为一例。由于甲壳动物由较低等的鳃足亚纲(如蚤、丰年虫)向较高等的软甲亚纲(糠虾、虾、蟹)进化,其个体发育的幼体阶段往往由简单向复杂发展,造成了甲壳动物幼体发育的多样性。     

斑节对虾Chitinase-2基因的克隆及其在蜕皮和幼体发育过程中的表达分析

研究以斑节对虾(Penaeus monodon)转录组获得的几丁质酶基因(Pm Chi)片段,运用RACE技术克隆了PmChi基因c DNA全长,命名为PmChi-2。PmChi-2基因c DNA全长2 050 bp,其中5'-非编码区(5'-UTR)144 bp、3'-UTR 319 bp和开放阅读框(ORF)1 587 bp,编码528个氨基酸。生物信息学分析显示,PmChi-2与其他甲壳动物Chi-2的相似性为78%~97%。实时荧光定量PCR结果显示,PmChi-2在蜕皮前期(D期)表皮中表达水平最高,在胃、鳃、腹神经节和眼柄中表达水平依次降低,在其他组织(肝胰腺、肠、肌肉、心脏)中几乎不表达。不同蜕皮阶段,PmChi-2在鳃、胃和表皮3种组织中的表达变化模式基本一致,均在蜕皮期(E期)表达量最低,而最高表达量在鳃中出现在蜕皮后期(A期),在胃和表皮中为D期。幼体不同发育阶段分析揭示PmChi-2 mRNA在幼体发育阶段的无节幼体到糠虾幼体第二期表达量维持在一个低水平,在糠虾幼体第三期PmChi-2 mRNA表达水平显著升高,在仔虾期又显著下降,推测PmChi-2 mRNA可能与斑节对虾幼体发育密切相关。研究结果表明PmChi-2基因可能在斑节对虾蜕皮以及幼体的变态发育中发挥重要作用,为深入研究斑节对虾几丁质酶发育调控提供了重要信息。     

人工繁殖蟹苗淡化方法的初步研究

人工繁殖蟹苗淡化方法的初步研究陆开宏，徐如卫，江锦坡（浙江水产学院养殖系，宁波３１５０１０）河蟹（Ｅｒｉｏｃｈｅｉｒｓｉｎｅｎｓｉｓ）系海水繁殖、淡水生长的洄游性甲壳动物，人工繁殖的蟹苗（大眼幼体）由于自身调节渗透压的需要，一般均需淡化后才移入淡水放...     

甲壳动物幼体消化酶研究进展

通过研究近年来国内外学者关于甲壳动物幼体消化酶方面的研究现状,发现目前已测定出甲壳动物幼体消化酶的种类主要有：蛋白酶、胰蛋白酶、羧肽酶A、羧肽酶B、氨肽酶、胶原酶、弹性蛋白酶、胃蛋白酶、糜蛋白酶、酯酶、脂肪酶、淀粉酶、纤维素酶、几丁质酶、麦芽糖酶、蔗糖酶、昆布多糖酶等种类,初步归纳了甲壳动物幼体主要消化酶的分子量、最适pH和最适温度;分析了幼体发育过程中消化酶活力变化模式以及与食性的关系,并采用淀粉酶/蛋白酶活力（A/P）比值或淀粉酶/类胰蛋白酶（A/T）比值作为甲壳动物幼体的食性指标;观察了幼体消化器官的发育,阐明幼体消化酶的合成与分泌不仅由遗传控制、中肠腺发育程度等因子决定,而且还与饲料的营养水平有关,提出采用幼体消化酶对饲料组成的适应性研究幼体营养需求的新途径.[中国水产科学,2006,13（3）：492-501]     

黑斑口虾蛄消化酶的初步研究

虾蟹等经济类甲壳动物的消化酶研究是甲壳动物消化生理研究的重要组成部分 ,也是人工育苗和养殖过程中投饵的理论依据。Ｋａｍａｒｕｄｉｎ等分别对斑节对虾和罗氏沼虾幼体消化酶进行过研究[1,2 ] ,Ｒｏｄｒｉｇｕｅｚ ,刘玉梅等 ,魏华等分别报道过日本对虾、中国对虾、罗氏沼虾幼体的消化酶的研究结果[3～ 5] 。黑斑口虾蛄 (Ｏｒａｔｏｓｑｕｉｌｌａｋｅｍｐｉ)是浙江沿海常见的具有较高经济价值的虾蛄种类 ,其养殖和人工育苗已有研究 ① ,但关于其消化酶的研究尚未见报道。为此 ,本文对黑斑口虾蛄幼体及成体的消化酶进行研究 ,旨在为其养…     

中华绒螫蟹幼体日粮和生长效率的初步研究

目前国内对物质和能量的主要研究对象是鱼类、对虾类和龟鳖类[1～ 7] 。何林岗[8,9] 曾测定了河蟹和青虾各期幼体的摄食量 ;周鑫[4 ] 研究了河蟹Ⅰ期蚤状幼体对钝顶螺旋藻的摄食和消化率。周名江[10 ] 对单胞藻 -卤虫的能量流动进行了研究。至今未见中华绒螯蟹 (Ｅｒｉｏｓｈｅｉｒｓｉｎｅｎｓｉｓ)幼体物质和能量转换效率方面的报道。研究物质和能量的转换效率不仅在生态学上具有重要意义 ,而且能指导蟹类的养殖生长及科学管理1　材料与方法1 .1　实验场地和用水实验于 1 997年在海南万宁市万州罗氏沼虾孵化场进行 ,海水为天然海水 (盐度 …     

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.