红螯螯虾对温度耐受性的试验

测定了红螯螯虾幼虾和虾苗对温度的耐受性。３８℃时，虾苗仅能存活４ｄ，幼虾仅能存活３ｄ；３５℃１５ｄ后虾苗存活４０％，幼虾存活７０％。２５℃时，虾苗和幼虾的成活率分别为９３．３％和１００％。１５℃时１５ｄ后虾苗存活６３．３％，幼虾存活１００％。１０℃时虾苗８ｄ全部死亡，幼虾１５ｄ后存活９０％。幼虾８℃时，１５ｄ后存活２０％，５℃时４ｄ全部死亡。     

红螯螯虾人工繁殖技术研究：II.红螯螯虾人工繁殖技术的探讨

红螯螯虾在厦门地区可以生长繁殖，其繁殖期为５－１０月份，盛期出现在６－８月份。每年自然水温上升至２６．３－２９．３℃时，受精卵孵化至稚虾需４２－４７天。用塑料编织网作为幼苗隐蔽栖息材料，投喂对虾苗在用１－２号配合饲料育效果理想。平均水温为２８℃时，由离开母体的稚虾（体长８ｍｍ）培育至体长为２－２．５ｃｍ的规格种苗，约需２５天。在正常情况下，每平方米育苗池，可生产出种苗１２３４－１９１０尾。     

澳大利亚红螯螯虾对水中氨氮浓度耐受性的研究

澳大利亚螯螯虾氨氮急性中毒试验的结果表明，在水温２１－２２℃，ｐＨ６．７－７．２时，该虾对水中氨氮浓度的耐受性为：４８小时的ＬＣ５０为１１８．０６ｍｇ／Ｌ，而且ＬＣ５０值随试验时间的延长而降低。     

高温应激对克氏原螯虾免疫酶活性及抗WSSV感染的影响

为探明高温应激对克氏原螯虾(Procambarus clarkia)抗病力的影响,分别采用30℃和35℃水温进行高温应激试验,应激前和应激后3、6、12、24和48 h分别采集血淋巴样本,测定总超氧化物歧化酶(T-SOD)、多酚氧化酶(PPO)、溶菌酶(LYZ)、酸性磷酸酶(ACP)以及碱性磷酸酶(ALP)等免疫相关酶类指标。并在上述高温应激下开展白斑综合征病毒(WSSV)人工感染实验,同时设置25℃为阳性和阴性对照组,于感染后3、6、12、24、48、72 h取鳃组织定量测定WSSV在组织中的载量,同时记录克氏原螯虾的发病和死亡情况,统计累积死亡率。结果显示,克氏原螯虾血淋巴中的T-SOD与LYZ含量在高温应激后都出现了显著性降低,而PPO、ACP和ALP的变化差异不大。在35℃饲养条件下,WSSV在克氏原螯虾体内的增殖受到抑制,实验虾发病慢,累积死亡率相对较低,但在30℃饲养条件下,WSSV在克氏原螯虾体内的增殖较常温(25℃)下更活跃,发病和死亡更快。结果表明,高温应激能导致克氏原螯虾机体非特异性免疫力降低,30℃时能加快克氏原螯虾感染WSSV的发病进程,而35℃时因病毒复制被抑制而导致疾病的发展受阻。     

美洲地区对虾TSV、IHHNV、WSSV和YHV病毒的流行现状、诊断方法及防治对策 (二)

２．托拉综合症病毒（ＴＳＶ） 根据其病毒颗粒结构（无囊膜的二十面体，３０ｎｍ直径，带胞质复制体，一个单链ＲＮＡ基因组），ＴＳＶ被归类为细小核糖核酸病毒 （ｐｉｃｏｒｖｉｒｕｓ）。 ＴＳＶ于１９９２年首次发现于瓜亚基尔（Ｇｕａｙｏｇｕｉｌ）湾托拉河口附近的对虾养殖场，造成池塘养殖的南美白对虾幼虾６０％－９０％死亡的灾难性损失。接着作为一种严重的病害，ＴＳＶ很快在拉美国家和美国的部分养虾地区流行蔓延。流行病学和实验室研究以及从厄瓜多尔向外的传播都表明，ＴＳＶ是一种病毒性病原，而且在美洲的南美白对虾、蓝…     

红螯螯虾室内产卵及其卵的发育

红螯螯虾原产于澳大利亚地区，最佳生长温度为２２～３０℃，年可产卵３～５次，６个月即可长至５０～８０ｇ，达到上市规格。生长快、易驯养是其特点。由于红螯螯虾原产于热带区域，冬季在室外不能存活，因此，成虾和稚虾必须在室内越冬。产卵主要受水温和日照时间的影响...     

反向间接血凝法检测对虾肝胰腺细小病毒的方法学研究

用密度梯度离心纯化的对虾肝胰腺细小病毒（ＨＰＶ）颗粒免疫家兔制备特异性抗血清，产建立了一种反向间接血凝法以诊断ＨＰＶ感染。该方法的敏感性可达ｎｇ／ｍｌ病毒蛋白的检测限水平。通过对１０份已固定的患病对虾肝胰腺样品分别取一小部分进行检测，证实反向间接血凝法与组织病理检查的相符性良好，而前者具有方法简便、重复性好、试剂稳定和样品检测可在１．５－２小时内 完成等特点，适合在现场推广使用。     

白斑综合征病毒感染克氏原螯虾后的PCR检测及组织病理学研究

采用投喂感染白斑综合征病毒(White Spot Syndrome Virus,WSSV)对虾肌肉的方式,对养殖克氏原螯虾(Procambarus clarkii)进行人工感染,以确定WSSV对养殖克氏原螯虾的易感性。结果发现,投喂病虾感染组螯虾的死亡率达到90%,而对照组未出现死亡。采用PCR对试验组螯虾的肌肉进行WSSV检测,发现投喂感染组的阳性检出率为100%,对照组的阳性检出率均为0。PCR检测结果发现,濒死螯虾的肝胰腺、中肠、肌肉、鳃、性腺、心脏六种组织的PCR结果均为WSSV阳性,而对照组的各组织检测结果均为阴性。组织切片的光镜观察也证实,濒死螯虾的肝胰腺、中肠、肌肉、鳃、性腺、心脏及血淋巴等组织均发生了不同程度的病变。     

红螯螯虾低温胁迫下应激行为及抗低温措施研究

将体质量（70±2.52）g红螯螯虾（Cherax quadricarinatus，又名澳洲淡水龙虾）饲养在60 cm×50 cm×40cm聚乙烯养殖箱中，通过控制降温缓急和改善饲料成分来设计实验方案。实验初期在21℃～23℃水温中增强体质30 d后，从室温匀速升温至25℃适应8 d，然后进入中温胁迫期和急降组（CJ、GJ）,3 d内降温至18℃，此后20 d维持18℃不变；缓降组（CH、GH）7 d内降温至18℃，此后16 d维持18℃不变；最后为低温胁迫期，急降组3 d内由18℃降温至低温6℃，此后7 d维持温度不变；缓降组7 d内由18℃降温至室外低温6℃，此后3 d维持温度不变。常规急降组、常规缓降组增强期（30 d）内投喂常规饲料；强化急降组、强化缓降组在体制增强期投喂抗低温饲料，研究不同降温方式和投喂不同饲料对红螯螯虾在低温胁迫下的摄食、行为及存活率，以寻求有效措施降低养殖生产中低温或寒灾的危害。结果表明，水温低于10℃时，红螯螯虾断螯、卷曲、侧翻；水温低于7℃僵硬、昏迷，水温降至6℃时大规模死亡，6℃为红螯螯虾临界致死低温。死亡时，身体的头胸甲和腹部连接处脱离、水肿，身体...     

提高稚鳖孵化率的技术要点

甲鱼人工孵化的技术要点有以下几个方面：１．温度；２．湿度；３．通气条件。 （１）温度：鳖卵孵化能适应的温度范围在２２－３６℃，最适温度范围在３０－３５℃，最佳温度为３２℃，孵化积温为 ３６０００度·时，孵化时间约为５０天。当孵化温度低于３０℃时，孵化积温大于３６０００度·时；当孵化温度高于３０℃时，孵化积温小于３６０００度·时。鳖卵在３６℃以上几小时就会导致胚胎死亡。２５℃以下，会使胚胎发育缓慢，２２℃以下停止发育。而且昼夜温差变化大会延长孵化时间，降低孵化率。 （２）湿度：孵化用沙含水量应保持在…     

中国对虾雄性生殖系统感染WSSV在其垂直传播中的作用

通过人工感染实验,对中国对虾(Fenneropenaeus chinensis)雄性亲虾进行投喂感染。在确定其携带WSSV粒子后,将被WSSV感染的精荚人工移植到健康的雌虾纳精囊内。在无其他病源的情况下,促其产卵繁殖,统计各组子代的受精率、孵化率及无节幼体至溞状幼体的变态率贸?式PCR技术对亲虾及子代进行WSSV检测。结果表明,受WSSV感染的精荚能够把病毒传播给健康雌虾,雌虾能产出携带WSSV的卵子,培育出带毒幼体。各组子代的受精率、孵化率及变态率的统计结果表明,感染组和对照组在受精率上没有明显区别,受WSSV感染的精卵细胞可以正常结合。对照组受精卵的孵化率明显高于感染组,差异显著(P=0.045<0.05)。对照组无节幼体的变态率也高于感染组。说明WSSV的入侵对受精卵及幼体的发育有影响,WSSV感染导致部分受精卵及幼体不能正常发育或死亡。     

60Co辐照对对虾白斑综合征病毒(WSSV)的灭活效果

以超低温保存的感染了白斑综合征病毒(WSSV)的中国对虾制备的病毒粗提液为毒种，注射感染凡纳对虾并收集濒死虾，DNA斑点杂交检测每尾凡纳对虾WSSV感染状况。取DNA斑点杂交呈强阳性的30尾对虾，平均分为3组，病毒粗提液也平均分成3组，3组材料分别通过^60Co辐照，辐照时间分别为12、24和36h，辐照剂量为0．8KGy／h。辐照后的材料经PCR检测证实^60Co辐照不能完全破坏WSSV的DNA组成。以辐照后的感染白斑综合征病毒的对虾个体和白斑综合征病毒粗提液为感染毒种，人工感染健康凡纳对虾，验证^60Co辐照对病毒感染力的破坏作用，证实^60Co辐照可显著降低WSSV病毒粗提液的感染力，^60Co辐照可适当降低WSSV感染对虾的感染力。     

感染白斑综合症病毒中国对虾雄性生殖系统的PCR检测与电镜观察

通过人工投喂携带WSSV的毒饵，对性腺发育成熟的中国对虾（Fenneropenaeus chinensis）雄虾（♂）进行感染实验。采用nest-PCR（巢式PCR）技术，检测感染后的中国对虾雄性生殖系统受WSSV感染情况，同时选取感染严重的虾样进行电镜观察。巢式PCR检测结果表明，感染组中国对虾的精巢、输精管和精囊均被WSSV感染，其中精囊呈阳性的最多，输精管次之，精巢最少。通过电镜进一步观察发现，WSSV粒子只存在于精巢、输精管和精囊的结缔组织中，而在其他组织和生殖细胞中均未发现病毒粒子。其中，精巢中WSSV粒子存在于精巢内两个生精小管之间的结缔组织；输精管中WSSV粒子存在于管壁的结缔组织；精囊中WSSV粒子也只存在于精囊内膜的结缔组织和精荚膜的结缔组织中。PCR检测和电镜观察结果均表明，WSSV粒子能感染中国对虾的雄性生殖系统且对性腺感染存在着一定的组织特异性。     

Experimental infection of European crustaceans with white spot syndrome virus (WSSV)

Eight European marine and freshwater crustaceans were experimentally infected with diluted shrimp haemolymph infected with white spot syndrome virus (WSSV). Clinical signs of infection and mortalities of the animals were routinely recorded. Diagnosis was by direct transmission electron microscopy (TEM), DNA hybridization (dot-blot and in situ hybridization) using WSSV probes and by PCR using WSSV specific primers. High mortality rates were noted between 7 to 21 days post-infection for Liocarcinus depurator , Liocarcinus puber , Cancer pagurus , Astacus leptodactylus , Orconectes limosus , Palaemon adspersus and Scyllarus arctus . Mortality reached 100%, 1 week post-infection in P. adspersus . When infection was successful, direct TEM observation of haemolymph revealed characteristic viral particles of WSSV, some observed as complete virions (enveloped), others as nucleocapsids associated with envelope debris. WSSV probes showed strong positive reactions in dot-blots and by in situ hybridization in sections and specific virus DNA fragments were amplified successfully with WSSV primers. White spot syndrome virus was pathogenic for the majority of the crustaceans tested. This underlines the epizootic potential of this virus in European crustaceans.     

刀额新对虾原代淋巴细胞培养及其感染白斑综合征病毒（WSSV）的病理特征

为深入了解对虾白斑综合征病毒(WSSV)的致病机理和体外培养的对虾细胞对WSSV的敏感性,实验以1.5×L-15培养基培养刀额新对虾原代淋巴细胞,待细胞形成单层后接种WSSV,通过倒置显微镜、荧光显微镜、透射电子显微镜观察接种病毒后细胞的病理变化。结果显示,使用1.5×L-15培养基培养对虾淋巴组织,3 h后可观察到有细胞迁出,并能迅速形成单层,36 h后细胞的迁出汇合率可达80%,且能存活20 d以上。接种WSSV 24 h后,出现病变的细胞变圆、漂浮,细胞之间的网状结构消失,最后细胞破碎、溶解;接种WSSV 48 h后Hoechst 33342染色结果显示,感染的细胞核深染,且变形、膨大;电镜下,细胞核内含大量成簇分布的杆状病毒,细胞器被挤向细胞边缘,细胞膜轮廓模糊。研究表明,纯化的病毒粒子接种体外培养的淋巴细胞,能够使其产生明显病理变化,证明了WSSV对体外培养的淋巴细胞具有感染力,并且可在淋巴细胞中增殖。     

WSSV＋斑节对虾的血清免疫相关酶对人工感染WSSV粗提液的反应

用含3×103拷贝·g^-1、6×1062拷贝·g^-1和2×10^2拷贝·g^-1的对虾白斑综合征病毒（white spot syndrome virus,WSSV）粗提液和PBS液（对照）注射感染病毒携带量约1×10^5拷贝·g^-1的斑节对虾（Penaeusmonodon）,分别于第15分钟、第30分钟、第1小时、第3小时、第6小时、第12小时、第24小时、第48小时、第72小时取样,研究了WSSV感染对斑节对虾血清内酸性磷酸酶（acidphosphatase,ACP）、碱性磷酸酶（alkalinephospha—tase,AKP）、酚氧化酶（phenoloxidase,PO）、过氧化物酶（peroxidase,POD）和超氧化物歧化酶（superoxide dismutase,SOD）活性的影响。结果表明,在3种感染浓度下ACP、AKP、SOD活性总体呈现先上升后下降随后上升的趋势,其中SOD活性后期水平显著高于初期;PO、POD活性总体呈现先下降后上升随后下降最后上升的趋势,但PO后期活性水平与初期相当,而POD后期活性水平显著高于初期。各免疫相关酶的反应强度与WSSV的感染浓度存在一定关系,除ACP外其余4种酶的活性变化均以6×10^2拷贝·mL^-1浓度组最为敏感。PBS组5种免疫酶活性变化幅度均显著小于3种WSSV浓度感染组。     

Studies on the rotifer (Brachionus urceus Linnaeus, 1758) as a vector in white spot syndrome virus (WSSV) transmission

The rotifer Brachionus urceus (Linnaeus, 1758) was experimentally infected with the white spot syndrome virus (WSSV) by the virus-phytoplankton adhesion route in order to assess the possibility of rotifer acting as a vector of WSSV to infect the shrimp Fenneropenaeus chinensis (Osbeck, 1765) larvae at zoea stage III. The nested-PCR test revealed WSSV-positive results in the rotifers exposed to WSSV by the virus-phytoplankton adhesion route. Among 10 replicates in the infection treatment, 40% of F. chinensis larvae became WSSV-positive when fed with WSSV-positive rotifers, whereas all were WSSV-negative for F. chinensis when fed with WSSV-free rotifers. Though the mortality of shrimp larvae in the infection treatment (39.47 ± 15.44%) was higher than that in the control treatment (34.67 ± 15.11%), there was no significant difference in the mortality between them (P > 0.05). These results indicated that the rotifer could serve as a vector in WSSV transmission when ingested.     

Detailed monitoring of white spot syndrome virus (WSSV) in shrimp commercial ponds in Sinaloa, Mexico by nested PCR

WSSV has caused great losses to the global shrimp industry in recent years. This virus can infect shrimps asymptomatically. However, once the clinical signs are developed, mortalities can reach 100% in 3-10 days. PCR has been extensively used to detect WSSV in a specific and sensitive manner. Nested PCR is even more sensitive than single-step PCR and had been used for the detection of WSSV in asymptomatic populations. In this work, a detailed monitoring of WSSV by nested PCR in shrimp commercial ponds in Guasave County, State of Sinaloa, Mexico, is presented. Five ponds from two different farms were monitored for growth and presence of WSSV. At the beginning of the culture, ponds from both farms showed no or very slight WSSV presence. A 3-day period of rain occurred at both farms 10 and 14 weeks of culture for farms 1 and 2, respectively. At this time, WSSV was widely distributed in the shrimp populations of farm 1 according to nested-PCR data, although no visual symptoms were observed. In ponds of farm 2, WSSV was present at low level. However, the number of PCR-positive groups was drastically increased in both farms by nested and single-step PCR. Abrupt fluctuations in temperature and salinity were documented in farm 2 after the rain, which may have contributed to the increasing of viral load in the pond's shrimp populations. Twelve days after the rain period, estimated mortalities of 80% occurred in farm 1. Nevertheless, the study ponds at farm 2 culture continued normally for three more weeks and were harvested successfully (52% and 67% of survival for ponds 1 and 2, respectively). The removal of 40% and 50% of shrimp population 2-4 days after the raining period may have contributed to the thriving of the cultures. Analyses of the presence of WSSV in individuals of both sexes indicated that there is no preference for this virus to infect male or female shrimp. Also, no differences in weight were found between WSSV infected and non-infected individual shrimps, as well as nested-PCR positive against single-step PCR positive organisms. Nested PCR is more useful to monitor shrimp cultures than single-step PCR since it allows knowing how widely distributed the virus is in asymptomatically populations.     

Studies on pathogenicity and prevalence of white spot syndrome virus in mud crab, Scylla serrata (Forskal), in Zhejiang Province, China

Mud crab, Scylla serrata (Forskal), is the most commercially important marine crab species in China. In recent years, serious diseases have occurred in major mud crab culture regions in SE China. PCR detection of white spot syndrome virus (WSSV) in diseased mud crabs collected from Zhejiang Province during 2006–2008 showed a prevalence of 34.82%. To study the pathogenicity of WSSV to mud crab, healthy mud crabs were injected intramuscularly with serial 10‐fold dilutions of a WSSV inoculum. The cumulative mortalities in groups challenged with 10^?1, 10^?2, 10^?3 and 10^?4 dilutions were 100%, 100%, 66.7% and 38.9% at 10 days post‐injection, respectively. All moribund and dead mud crabs except the control group were positive for WSSV by PCR. Based on the viral load of the WSSV inoculum by quantitative real‐time PCR, the median lethal dose (LD50) of WSSV in S. serrata was calculated as 1.10 × 10⁶ virus copies/crab, or 7.34 × 10³ virus copies g^?1 crab weight. The phenoloxidase, peroxidase and superoxide dismutase activities in haemolymph of WSSV‐infected moribund crabs, were significantly lower than the control group, whereas alkaline phosphatase, glutamate‐pyruvate transaminase and glutamic‐oxaloacetic transaminase were higher than in the control group. WSSV was mainly distributed in gills, subcuticular epithelia, heart, intestine and stomach as shown by immunohistochemical analysis with Mabs against WSSV. The epithelial cells of infected gill showed hypertrophied nuclei with basophilic inclusions. Numerous bacilliform virus particles were observed in nuclei of infected gill cells by transmission electron microscopy. It is concluded that WSSV is a major pathogen of mud crab with high pathogenicity.