养殖对虾弧菌病致病菌——非01群霍乱弧菌的生物学性状与致病性

本文对养殖对虾所患的一种弧菌病作了研究报道。这种病的病原是非01群霍乱弧菌。这是一种菌体短的无芽孢杆菌，弧状，单个，有时联成S状。以一根单极毛运动，鞭毛有外鞘。草兰氏染色阴性。生化反应和已知的01霍乱弧菌基本相同，但不被01霍乱弧菌多价血清凝集。这种病的症状是行动呆滞，时而浮头或在水面上翻滚；眼球肿胀，由黑变暗以至溃烂仅留眼柄，随着病情加重全身肌肉发白。一般在一周内死亡。     

Procurement decisions regarding shrimp supplies for Thai shrimp processors

Shrimps of all sizes are obtained by direct purchasing from independent farms then sorted and sold by size. Shrimp that has not been sold is kept in cold storage, a heavy burden for shrimp processors. In this paper, a mathematical model and a heuristic model based on the dynamic programming are developed to facilitate harvesting decisions for shrimp processors. The objective function of the proposed model is to minimize the cost related to by-size inventory. The effectiveness of the heuristic model is evaluated under a combination of scenarios with various parameters. The results demonstrate that the heuristic model is quite effective and practical in solving the problem.     

Oxygen consumption and ingestion rate of Penaeus setiferus larvae fed Chaetoceros ceratosporum, Tetraselmis chuii and Artemia nauplii

The effects of the density and type of food on oxygen consumption and ingestion rate of larvae of the white shrimp Penaeus setiferus fed diatoms Chaetoceros ceratosporum, flagellates Tetraselmis chuii and Artemia franciscana nauplii were analysed. Diatoms, flagellates and Artemia nauplii were fed at five densities from 10 to 5 × 10³ cells mL^?1, 0 to 4 × 10³ cells mL^?1, and 0.1, 0.5, 1.0, 1.5 and 2 nauplii mL^?1, respectively. In three experiments, two of three types of food were maintained constant at concentrations of 30-40 × 10³ cells mL^?1 (diatoms), 2 × 10³ cells mL^?1 (flagellates) and 1 Artemia nauplii mL^?1. The oxygen consumption in three experiments increased with larval stage, reaching maximum values in Mill except at lower feed concentrations. A maximum ingestion peak in MI was recorded in larvae fed diatoms, whereas that peak was observed in Mil in larvae fed flagellates. The maximum ingestion rate of Artemia nauplii was observed in Mill. Feed concentrations that produced an optimum metabolic rate as a consequence of equilibrium between ingested food and larval stages were obtained with 20 and 30 × 10³ cells mL^?1 of C. ceratosporum, 2 and 3 × 10³ cells mL^?1 of T. chuii, and 1.0 Artemia nauplii mL^?1. These concentrations would be the most suitable for producing P. setiferus postlarvae.     

Influence of sediment characteristics on shrimp physiology: pH as principal effect

Penaeid shrimp reared in earthen ponds are exposed to sediment, which can, in some instances, induce a stress. In seawater, the osmoregulatory capacity (hyporegulation) is a useful tool to compare the physiological condition of shrimp exposed to various stressors. By keeping some shrimp in cages at different locations of a single pond heterogeneous in terms of sediment quality, it was possible, using osmotic pressure (OP), to identify some locations where the stress was maximum and some others where it was minimum. Simultaneously, sediment samples were taken and analysed in order to evaluate some physico-chemical parameters that could be related to the stress observed in the shrimps kept in the cages. This approach allowed to show a significant positive correlation between the pH of the sediment surface and the shrimp osmotic pressure. This result was confirmed in a study carried out in experimental 70-l tanks, where osmotic pressure decreased significantly as water pH decreased from 7.0 to 6.5. The methodology developed in this study may be useful to evaluate the stress caused by sediment in shrimp farms.     

Economic returns of disease-affected extensive shrimp farming in southwest Bangladesh

One hundred and two brackish water shrimp farms in Shyamnagar Upazila of Satkhira District, Bangladesh, were surveyed to study their costs and returns. Key data were collected, using a questionnaire survey from January to August 2002. Profitability of operations was affected by fluctuating yields and prices due to diseases, and generated economic risk. The average total cost of production per hectare was 63,437.57 Bangladeshi taka (tk) (US$1,084.40/ha). The farmers achieved a variable yield of black tiger shrimp (Penaeus monodon), ranging from 7.48 kg/ha to 455.03 kg/ha, with a mean yield of 146.39 kg/ha, through multi-stock and multi-harvest methods. The gross and net incomes per hectare were tk49,999.87 (US$854.69) and tk40,307.04 (US$689.01), respectively. Of the total biomass, 44% came from P. monodon, while the rest (23% and 33%) came from other shrimp and finfish respectively. The return to total cost of P. monodon was a negative profit (tk0.78).     

渤海西小磨虾池氮、磷营养盐研究

西小磨1996年和1997年7－8月期间248个调查数据显示，NO2－N浓度范围和平均值沿岸分别是1．3－22．2μg/L和5．7μg/L，虾池分别是1．1－13．5μg/L和6．6μg/L，NO3－N范围和平均值沿岸分别是1．3－214．2μg/L5和70．7μg/L，虾池是2．3－159．7μg/L和36．1μg/L。NH4－N范围和平均值沿岸分别是未检出－37．9μg/L和6．7μg/L，虾池是未检出－106．8μg/L和10．8μg/L。PO4－P范围和平均值沿岸分别间1．6－11．0μg/L和4．9μg/L，虾池是0．74－18．8μg/L和4．0μg/L。虾池中氮、磷的特点是浓度上限值和平均值远较非养殖的远岸外海区高，氮、磷的变化趋势并不总是一致，降雨能导致虾池NO3－N和NO2－N的大幅度提高，但不能影响PO4－P和NH4－N。     

中国对虾风味物质的产生机理

运用气谱－质谱联用仪对中国对虾肌肉水溶性提取物蒸煮后产生的挥发性化合物进行研究，发现了一些对特征性虾风味有影响的化合物如烷基吡嗪类，噻唑，吡啶吲哚，二噻嗪，三噻茂烷等。提取物中添加Ｇｌｙ、Ａｌａ、Ａｒｇ、ＩＭＰ组成不同的模拟体系，加热后其主要挥发性成分与体系有关。海虾虾与养殖虾肌肉的风味成分之间略有不同，试验结果表明，产生特征性虾风味的主要前体物质有游离氨基酸，Ｇｌｙ、Ａｌａ、Ａｒｇ、Ｇｙｓ，糖类     

应用PCR和RT-PCR技术对4种对虾病毒的检测

探讨了应用PCR和RT－PCR技术对4种主要的对虾病毒进行检测的方法。同时使用该方法检测了对虾天然饵料－－卤虫中的4种对虾病毒。结果显示，含病毒核酸的阳性对照样品分别扩增出了大小为824bp,705bp,260bp和216bp的预期产物，但未能从卤虫样品中检测到此4种病毒的存在。本文报道的病毒检测方法具有快速、灵敏、准确的特点，可以用于进出口贸易中对活体或冰冻对虾，虾苗，对虾饵料等进行相关对虾病毒的检疫，也为制定我国对虾病毒检疫检验规范提供了技术参考。     

对虾白斑综合征病毒可视化环介导等温扩增(LAMP)检测技术的建立与应用

针对当前对虾(Penacus orientalis)养殖业亟需研究开发一种简便快速、敏感特异的检测技术来实现对对虾白斑综合征病毒(White spot syndrome virus,WSSV)进行检测监控的现状,本研究根据WSSV基因组ORF120保守区序列,设计合成6条环介导等温扩增(loop mediated isothermal amplification,LAMP)特异性引物,分别为外引物F3/B3、内引物FIP/BIP和环引物LF/LB。利用钙黄绿素/氯化锰作为检测指示剂,通过对反应条件优化,建立了可视化WSSV-LAMP检测方法。在检测中未发生扩增反应时,钙黄绿素被氯化锰螯合,呈淬灭状态。当样品中有WSSV靶基因存在时,大量DNA被合成,并产生同样大量的焦磷酸根离子,此时焦磷酸根离子竞争性与Mn2+结合,形成稳定的不溶性焦磷酸盐沉淀,钙黄绿素被释放而发出肉眼可见的黄绿色荧光。该扩增一次性反应约60min即可完成对待检样品的检测。经测定,本方法能特异性地检测出阳性样品中的WSSV目的基因,并能通过扩增产物所产生的黄绿色变化与阴性样品区别;本技术对目的基因的最低检测量为1fg。在临床检测试验中,WSSV-LAMP与世界动物卫生组织(OIE)推荐的WSSV-PCR检测方法均能从250份对虾样品中,同时检测到15份编号相同的阳性样品,符合率达100%。除此之外,WSSV-LAMP还能从另外3份PCR检测为阴性的样品中检测到目的基因。比较这两种方法的阳性检出率,WSSV-LAMP为7.2%(18/250),WSSV-PCR为6.0%(15/250),WSSV-LAMP对自然感染的临床样品阳性检出率要比WSSV-PCR高。说明WSSV-LAMP在病毒含量较低的临床样品检测中比OIE推荐的PCR方法具有更高的技术优势,能在对虾养殖生产上的临床诊断、育种及口岸检疫,甚至海洋生态监测中对WSSV进行现场检疫。