斑节对虾Pellino基因的克隆及其在不同胁迫条件下的表达分析

Pellino蛋白家族,是一类高度保守的E3泛素连接酶,在泛素化和先天性免疫中发挥重要作用。该研究通过RACE技术得到斑节对虾(Penaeus monodon)泛素连接酶Pellino基因的c DNA全长。该基因序列全长1 961 bp,编码区序列长1 299 bp,编码432个氨基酸,5’非编码区(UTR)为89 bp,3’UTR为573 bp。通过qRT-PCR技术,研究了PmPellino基因在斑节对虾不同组织中的表达水平,并研究了其在不同浓度氨氮胁迫下和不同微生物刺激下的表达情况。结果显示,PmPellino基因在各组织中均有表达,在鳃组织中表达量最高。急性氮氮胁迫后,PmPellino在肝胰腺中的表达量显著上调(P<0.01),但在鳃中的表达被抑制(P<0.01)。哈维氏弧菌(Vibrio harveyi)可显著激活PmPellino在鳃中的表达,抑制其在肝胰腺中的表达。鳗弧菌(V. anguillarum)可显著抑制PmPellino在肝胰腺中的表达,而对PmPellino在鳃中的表达无显著影响。金黄色葡萄球菌(Staphylococcus aureus)可以显著激活PmPellino在肝胰腺和鳃中的表达。结果表明PmPellino可以激活免疫应答通路,在免疫防御中发挥重要作用。     

中国对虾血蓝蛋白基因cDNA的克隆与序列分析

利用3’和5’RACE技术从中国对虾Fenneropenaeus chinensis肝胰腺中克隆了1个血蓝蛋白基因FCHc,FCHc基因cDNA全长为2161bp。其中,开放阅读2 034bp,编码678个氨基酸,预测分子量为77.59 kDa。FCHc序列与凡纳滨对虾Litopenaeus vannamei血蓝蛋白同源性为82%,与日本囊虾Marsupenaeus japonicas同源性为85%。Real-timePCR实验结果表明,FCHc在肝胰腺中的相对表达量最高,在心脏和表皮中几乎不表达。该基因在鳗弧菌和对虾白斑综合征病毒(WSSV)感染后的对虾肝胰腺中的表达量显著增加,并具有不同的时空表达趋势,提示中国对虾FCHc基因在免疫反应中具有重要作用。     

凡纳滨对虾LvML1基因克隆与表达分析

髓样分化蛋白2相关脂质识别(ML)蛋白是无脊椎动物先天免疫与脂质代谢方面具有重要功能的一类蛋白。克隆凡纳滨对虾1个新的ML基因cDNA全序列，命名为LvML1,包含254 bp的5′非编码区、913 bp的3′非编码区和462 bp的开放阅读框，开放阅读框共编码153个氨基酸。LvML1蛋白具有7个半胱氨酸残基，预测可形成3对二硫键，且具有1个典型ML家族结构域。多重序列对比发现，ML结构域和半胱氨酸残基位置均相对保守。系统进化显示，LvML1蛋白与斑节对虾、日本囊对虾、美洲螯龙虾等甲壳动物的ML蛋白聚为一支。实时荧光定量PCR结果显示，LvML1基因在所有检测组织中均有表达，在心脏中表达量最高。发育表达结果显示，LvML1基因自无节幼体期已有表达，在变态至溞状幼体期、糠虾幼体期及仔虾的每次转换均上调表达，表明其参与了对虾幼体的发育过程。十足目虹彩病毒1人工感染24 h后，LvML1基因在肝胰腺和鳃中表达量下降，差异极显著(P<0.01),说明其参与了对虾抗病毒的先天免疫过程。本试验结果可为了解凡纳滨对虾ML蛋白家族的结构功能及其在对虾先天免疫和幼体发育中的重要作用提供基础资料。     

斑节对虾泛素融合蛋白UbS27基因克隆与表达分析

从构建的斑节对虾(Penaeus monodon)肝胰腺转录组数据中筛选出泛素核糖体融合蛋白Ub S27基因(ubiquitin/ribosomal S27 fusion protein,Pm Ub S27)片段,利用SMART-RACE技术克隆出Pm Ub S27基因c DNA全长,并利用软件对其结构进行分析;利用实时荧光定量技术检测Pm Ub S27基因在斑节对虾不同组织及卵巢不同发育期的表达情况。结果显示,Pm Ub S27基因c DNA全长为514 bp,开放阅读框465 bp,编码154个氨基酸,含有泛素(1~72 aa)和核糖体蛋白(101~147 aa)2个结构域。以DNA为模板克隆得到的基因序列由3个内含子和4个外显子组成。实时荧光定量结果显示,Pm Ub S27基因在斑节对虾各组织中均有表达,但是在卵巢中表达量最高,其次为肝胰腺、血淋巴和精巢。Pm Ub S27在卵巢发育前期(Ⅱ期)和成熟期(Ⅴ期)的表达量显著高于其他各期(P0.05)。结果表明,Pm Ub S27参与斑节对虾卵巢发育的过程并可能在卵巢发育进程中起到重要的调控作用。     

斑节对虾天门冬氨酸转氨酶基因的克隆及氨氮胁迫条件下的表达分析

为了探索天门冬氨酸转氨酶(AST)在斑节对虾(Penaeus monodon)氨氮(NH3-N)解毒代谢中的作用,该研究利用RACE技术获得了斑节对虾AST基因(PmAST)的cDNA全长序列,进行了相关生物信息学分析,在此基础上采用荧光定量与氨氮胁迫实验的方法研究了PmAST基因在斑节对虾的不同组织以及不同浓度氨氮胁迫过程中差异表达情况。该序列全长1 957 bp,开放阅读框(ORF)为1 242 bp,3'非编码区(UTR)为584 bp,包括含有30个碱基的poly(A)尾,5'非编码区(UTR)为131 bp。ORF可编码413个氨基酸,预测分子量为45.852 kD,理论等电点为8.85。序列含有1个AAT-like超家族结构域、15个磷酸化位点和2个糖基化位点。PmAST的mRNA在斑节对虾各组织中都有表达,在肝胰腺中表达量最高,其次为鳃组织,在胃和脑组织中的表达量最低。96 h氨氮胁迫后荧光定量PCR分析结果表明,PmAST在肝胰腺和鳃组织中都具有不同程度的表达上调,显著高于对照组(P0.05)。研究结果表明斑节对虾的PmAST基因在氨氮胁迫条件下会出现表达上调,并且氨氮浓度越高其上调幅度也越大,所以PmAST参与了斑节对虾的急性氨氮胁迫应答。     

脊尾白虾热休克蛋白HSP70基因的克隆及其表达分析

克隆了脊尾白虾热休克蛋白基因全长cDNA,并进行了序列分析。该基因由2 250 bp的碱基组成,开放阅读框长1 959 bp,编码由652个氨基酸组成的蛋白,基因两翼分别存在83 bp(5′端)和208 bp(3′端)的非翻译区,将该基因命名为Ec-HSP70。与其它物种HSP70s氨基酸序列进行同源性比较发现,与甲壳动物的同源性都在90%以上,表明该蛋白属于热休克蛋白HSP70家族。聚类分析表明,脊尾白虾热休克蛋白氨基酸序列与中国明对虾和凡纳滨对虾紧密聚为一支,之后聚类顺序依次为斑节对虾、日本囊对虾、刀额新对虾等。通过荧光定量RT-PCR对该基因在肝胰腺、肌肉的表达分析表明,温度、pH和氨氮胁迫都可以引起该基因的高表达,而且肝胰腺中的高表达时间相对肌肉中出现的较早。试验结果表明,温度、pH和氨氮胁迫对脊尾白虾HSP70基因表达有一定的诱导效果,但胁迫的时间过长则抑制其表达,肝胰腺对胁迫比肌肉较敏感。     

凡纳滨对虾黏着斑激酶基因克隆与合并感染条件下的免疫应答

采用RACE技术克隆凡纳滨对虾黏着斑激酶基因,利用相关软件工具拼接、比对其序列,构建进化树,同时利用荧光定量技术分析了该基因的组织分布和合并感染下的免疫应答。试验结果显示,凡纳滨对虾黏着斑激酶基因cDNA序列全长4919bp,ORF片段长3036bp,编码1012个氨基酸。凡纳滨对虾黏着斑激酶基因具有蛋白激酶特征结构域PTK和C端的对虾黏着结构域。荧光定量结果表明,凡纳滨对虾黏着斑激酶基因表达无组织特异性,眼部表达量最高,肌肉中表达量最低,可以被副溶血弧菌与白斑综合症病毒以及二者的合并感染诱导表达,表达量先升再降,整个试验过程中合并感染组斑激酶表达量总是高于白斑综合症病毒单独感染组。酶活测定结果表明,合并感染组酸性磷酸酶活力变化最活跃;试验后期,弧菌单独感染组碱性磷酸酶活力始终高于合并感染组,合并感染组过氧化物酶活力总是高于白斑综合症病毒单独感染组;整个试验过程中,弧菌单独感染组超氧化物歧化酶活力始终高于其他两个感染组。     

凡纳滨对虾脂肪酸结合蛋白基因全长cDNA的克隆及序列分析

克隆了凡纳滨对虾脂肪酸结合蛋白基因全长cDNA并进行了序列分析。该基因由1042bp的碱基组成,开放阅读框长411bp,编码由136个氨基酸组成的蛋白,基因两翼分别存在113bp(5'端)和518bp(3'段)的非翻译区。聚类分析表明,凡纳滨对虾脂肪酸结合蛋白氨基酸序列与斑节对虾脂肪酸结合蛋白紧密聚为一支,之后聚类顺序依次为刀额新对虾、意大利蜜蜂、斑马鱼、大西洋鲑、鸡、猪和人。通过半定量RT-PCR对该基因在不同组织的表达分析表明,该基因在抗IHHNV对虾肠、胃、肝胰腺和肌肉组织中表达较高,在心肌中表达较低,在眼柄中不表达。比较该基因在抗IHHNV对虾和IHHNV易感对虾心、肝胰腺、肠、胃、眼柄和肌肉组织表达发现,该基因在两种对虾心、肠、胃和肌肉组织中的表达无明显差异,但在肝胰腺中抗IHHNV对虾的表达量明显高于IHHNV易感对虾的表达量,说明该基因参与抗性对虾抑制IHHNV感染的免疫过程。     

中国明对虾酚氧化酶原基因cDNA的克隆与表达特征

利用3′和5′RACE技术从中国明对虾血细胞中克隆了一个酚氧化酶原基因FCproPO,FCproPO基因cDNA全长为2311bp,其中开放阅读框2061bp,编码687个氨基酸,预测分子量为78.71ku。推测的序列与凡纳滨对虾同源性为84%,与日本囊对虾同源性为71%。RT-PCR实验结果表明,FCproPO在血细胞中的相对表达量最高,在心脏和精巢中几乎不表达。序列分析发现FCproPO含有两个保守的铜离子结合位点;进化分析发现FCproPO与斑节对虾、日本囊对虾、凡纳滨对虾等海水虾的酚氧化酶原亲缘关系最近。该基因在被鳗弧菌和对虾白斑病毒(WSSV)感染后的对虾肝胰腺中的表达量显著增加,并具有不同的时空表达趋势,提示中国明对虾FCproPO基因在免疫反应中具有重要作用。     

中国明对虾caspase2基因克隆及其在抗白斑综合征病毒中的表达分析

采用RACE技术克隆获得中国明对虾caspase2基因cDNA序列全长,并对该序列进行分析。结果显示,中国明对虾caspase2基因全长为1517 bp,开放阅读框长924 bp,5'非编码区长78 bp,3'非编码区长515 bp,命名为FcCasp2。推测该基因编码307个氨基酸,预测分子量为34.21 ku,理论等电点为7.62。同源性和系统进化分析发现,FcCasp2基因与凡纳滨对虾caspase2和斑节对虾caspase的相似性分别为88%和80%,与其他节肢动物caspase家族基因聚为一类。荧光定量RT-PCR结果显示,FcCasp2基因在肝胰腺中的相对表达量最高,在肌肉中表达量最低。WSSV感染后该基因在中国明对虾肌肉、肝胰腺和鳃丝中的表达量有不同的时空表达趋势,表明FcCasp2基因可能参与中国明对虾生物胁迫的应答反应。     

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.     

美人鱼发光杆菌对凡纳滨对虾非特异性 免疫功能及抗病力的影响

在基础饲料中分别添加0.1%和1%美人鱼发光杆菌灭活菌、0.1%美人鱼发光杆菌活菌配制成3种免疫实验饲料,以基础饲料为空白对照组饲料,每组设3个平行样。对个体质量为(4.83±0.36)g的凡纳滨对虾进行为期20 d的饲养实验,分别在0、5、10、15和20d进行取样,以血清中的酚氧化酶(PO)、酸性磷酸酶(ACP)、碱性磷酸酶(AKP)、超氧化物歧化酶(SOD)和溶菌酶(UL)活性为免疫指标,探讨了美人鱼发光杆菌作为免疫制剂对凡纳滨对虾非特异性免疫效应的影响;在投喂免疫饲料后的第22天,按0.004 2 kg/kg体重的剂量,直接投喂对虾白斑综合征病毒(WSSV)病料,并记录累积死亡率。结果表明,美人鱼发光杆菌免疫实验组对凡纳滨对虾血清中PO、ACP、AKP、UL和SOD活性影响明显高于对照组,并且在饲料中添加美人鱼发光杆菌后,明显提高了对虾抵御WSSV感染的能力。其中0.1%美人鱼发光杆菌活菌实验组的抗病毒感染能力最强,WSSV感染14d内累计死亡率为63.3%±5.8%;而对照组为96.7%±3.3%。研究表明,美人鱼发光杆菌添加在对虾饲料中能提高凡纳滨对虾非特异性免疫水平,增强抵抗疾病的能力,将其作为对虾免疫增强剂具有良好的应用前景。     

Growth hormone (GH) and reproduction: a review

Interaction between growth and reproduction occurs in many vertebrates and is particularly obvious at certain stages of the life cycle in fish. Endocrine interactions between the gonadotropic axis and the somatotropic axis are described, the potential role of GH being emphasised. A comparative analysis of these phenomena in mammals, amphibians and fish, suggests a specific role of GH in the physiology of puberty, gametogenesis and fertility. It also shows the original contribution made by studies on the fish model in this field of investigations.     

Effects of Spirulina platensis as a feed additive on growth and coloration of blue dolphin cichlids (Cyrtocara moorii Boulunger, 1902)

This study was carried out to investigate the effects of replacing fish meal with dietary Spirulina as a feed supplement on the growth performance and coloration of blue dolphin cichlids (Cyrtocara moorii). Five isonitrogenous (47% crude protein) and isocaloric (17.36 kJ/g digestible energy) diets were for formulated to replace FM with 0, 5, 10, 15 and 20% Spirulina (designated as Control, SP5, SP10, SP15 and SP20 respectively) and fed to the fish (initial body weight, 3.15 ± 0.01 g). Fish were randomly distributed into fifteen 120 L aquariums (26.5 ± 1.00°C), 15 fish per aquarium. The diets were tested in triplicate for 12 weeks. Experimental groups were fed twice daily (09:00 and 17:00) by hand to satiation. At the end of the feeding trial, significantly (p < 0.05) higher weight gain (WG), specific growth rate (SGR), protein efficiency ratio (PER) and lower feed conversion ratio (FCR) were observed in fish fed the SP10 diet when compared to the SP20 diet. There was no significant difference in these parameters between the other groups. The skin coloration of blue dolphin cichlid fed a diet containing Spirulina meal was enhanced. The best coloration was observed in the SP15 group. These impressions were objectively validated by chemical determinations of carotenoids extracted from fish skins and passed statistical tests of significance. The study findings show that Spirulina meal does not diminish growth rates except at very high levels.     

A Minchinia mercenariae‐like parasite infects cockles Cerastoderma edule in Galicia (NW Spain)

The cockle Cerastoderma edule fishery has traditionally been the most important shellfish species in terms of biomass in Galicia (NW Spain). In the course of a survey of the histopathological conditions affecting this species in the Ria of Arousa, a haplosporidan parasite that had not been observed in Galicia was detected in one of the most productive cockle beds of Galicia. Uni‐ and binucleate cells and multinucleate plasmodia were observed in the connective tissue mainly in the digestive area, gills and gonad. The parasite showed low prevalence, and it was not associated with abnormal cockle mortality. Molecular identification showed that this parasite was closely related to the haplosporidan Minchinia mercenariae that had been reported infecting hard clams Mercenaria mercenaria from the Atlantic coast of the United States. The molecular characterization of its SSU rDNA region allowed obtaining a fragment of 1,796 bp showing 98% homology with M. mercenariae parasite. Phylogenetic analysis supported this identification as this parasite was clustered in the same clade as M. mercenariae from the United States and other M. mercenariae‐like sequences from the UK, with bootstrap value of 99%. The occurrence of M. mercenariae‐like parasites infecting molluscs outside the United States is confirmed.     

Sea bream culture in Egypt; status, constraints and potential

Marine fish farming in Egypt began in 1976 with the culture of gilthead sea bream, (Sparus aurata) as this fish was notably adaptable to brackish and marine pond conditions. Today, marine fish and shrimp farms amount to about 19,000 ha, out of which 42% is already in production while the rest, i.e., 58% is still under construction. In 1997, cultured gilthead sea bream production of 2,250 tons made up 3% of the 75,000 tons total aquaculture catch. In polyculture, usually with the grey mullet and sea bass, gilthead sea bream contributed 440 kg ha^–1 to the total yield of 1,700 kg ha^–1 (26%) over a period of 16 months. For the same period, the yield of monoculture ponds averaged 100 kg ha^–1, while in marine cages, yields ranged from 4–10 kg m³. In 1996–1997, fry of 0.25–1 g and fingerlings 1–10 g with a total of 3 million, were collected from the wild and 1 million fry were produced in the three marine hatcheries out of the four existing ones. The development of sea bream culture in Egypt is now severely inhibited by the shortage of seeds and adequate feeds. Exports of both sea bream and sea bass, during 1994–1996 averaged 1,300 tons per year.     

Dietary thiamin and pyridoxine requirements of fingerling Indian major carp,Cirrhinus mrigala (Hamilton)

Two experiments were conducted to quantify the dietary thiamin (experiment I) and pyridoxine (experiment II) requirements of fingerling Cirrhinus mrigala for 16 weeks. In experiment I, dietary thiamin requirement was determined by feeding seven casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) with graded levels of thiamin (0, 0.5, 1, 2, 4, 8 and 16 mg kg^?1 diet) to triplicate groups of fish (6.15 ± 0.37 cm; 1.89 ± 0.12 g). Fish fed diet with 2 mg kg^?1 thiamin had highest specific growth rate (SGR), protein retention (PR), RNA/DNA ratio, haemoglobin (Hb), haematocrit (Hct), RBCs and best feed conversion ratio (FCR). However, highest liver thiamin concentration was recorded in fish fed 4 mg thiamin kg^?1 diet. Broken‐line analysis of SGR, PR and liver thiamin concentrations exhibited the thiamin requirement in the range of 1.79–3.34 mg kg^?1 diet (0.096–0.179 μg thiamin kJ^?1 gross energy). In experiment II, six casein–gelatin‐based diets (400 g kg^?1 CP; 18.69 kJ g^?1 GE) containing graded levels of pyridoxine (0, 2, 4, 6, 8 and 10 mg kg^?1 diet) were fed to triplicate groups of fish (6.35 ± 0.37 cm; 1.97 ± 0.12 g). Fish fed diet containing 6 mg kg^?1 pyridoxine showed best SGR, FCR, PR, RNA/DNA ratio, Hb, Hct and RBCs, whereas maximum liver pyridoxine concentration was recorded in fish fed 8 mg kg^?1 dietary pyridoxine. Broken‐line analysis of SGR, PR and liver pyridoxine concentrations reflected the pyridoxine requirement from 5.63 to 8.61 mg kg^?1 diet. Data generated during this study would be useful in formulating thiamin‐ and pyridoxine‐balanced feeds for the intensive culture of this fish.     

Nitrogenous waste excretion and accumulation of urea and ammonia inChalcalburnus tarichi (Cyprinidae), endemic to the extremely alkaline Lake Van (Eastern Turkey)

The endemic, anadromous cyprinidChalcalburnus tarichi is the only fish species known to occur in alkaline Lake Van (Eastern Anatolia, Turkey). EightC. tarichi were maintained individually in Lake Van water (17 – 19°C; pH 9.8; 153 mEq·I^–1 total alkalinity; 22 total salinity) and tank water samples analyzed for 24 h in 2 to 4 h intervals. At zero time, < 1µM ammonia was present and urea was undetectable in the tank water; at 24 h, total ammonia and urea made up 114±32 and 35±25µM, respectively. Over the experimental period, ammonia-N and urea-N excretion averaged 1041±494 and 607±169moles·kg^–1 fish·h^–1, respectively. The extent of urea excretion was highly variable between specimens. Uric acid excretion was not detectable.Urea was present at high concentrations in all tissues and plasma (25 – 35moles·g^–1·ml^–1) of freshly caughtC. tarichi; total ammonia content of the tissues was by a factor of 1.9 (liver) to 3.0 (brain) lower. High arginase activity (2.4±0.2 U·min^–1·g^–1) was detected in the liver ofC. tarichi but ornithine carbamoylphosphate transferase, a key enzyme of the ornithine-urea-cycle, was absent. Ureagenesis is likely through degradation of arginine and/or uricolysis. High glutamine synthetase activity (11±0.6 U·min^–1·g^–1) and low ammonia content in brain suggest that, like other teleosts,C. tarichi has an efficient ammonia detoxification in the brain, but in no other tissue.Nitrogenous waste excretion at alkaline pH is discussed. The ability ofC. tarichi to excrete high levels of ammonia at extremely alkaline pH is unique among teleosts studied so far. The mechanism of ammonia excretion under Lake Van conditions remains to be elucidated.