“脊尾白虾肌肉微孢子虫病”的病原和病理分析

江苏启东海水养殖脊尾白虾出现肌肉白化症状,虾腹部、头胸甲、步足、尾扇等部位病变明显,通过活体压片镜检发现肌肉中存在大量球形包囊,利用超显微技术对病原的形态和结构进行分析,确定其为微孢子虫,并对脊尾白虾的病变组织进行了病理分析。结果表明：该微孢子虫具包囊结构,包囊大小为（5.40±0.55） μm,一个包囊内含8个孢子,成熟孢子呈椭圆形,孢子长为（2.30±0.25） μm,孢子宽为（1.50±0.19） μm,孢内极丝一般环绕9~10圈。病理分析显示,脊尾白虾的鳃、胃、肠和肌肉内均发现微孢子虫寄生和不同程度的病变。其中,肌肉组织病变最严重：原肌纤维存在的空间被大量的球形包囊占据,肌纤维断裂,空泡数量增多,线粒体消失;鳃细胞膨大呈空泡状,鳃膜坏死,核质、细胞质和细胞器消失;胃细胞胞浆基质电子密度增大,孢子寄生在结缔组织中脂滴附近;肠外膜上皮细胞核质皱缩,部分肌层消失,孢子寄生在肠粘膜层和肌层之间。     

脊尾白虾养殖研究进展

脊尾白虾在我国黄渤海产量最多,营养丰富,是加工海米的上等原料。作为我国3种常见的经济虾类之一,白虾具有繁殖能力强、病害少、养殖周期短、适应性强和经济效益高等优点。本文综述了脊尾白虾的生物学特性以及在低盐和低温养殖条件下的生理学特征,以期为脊尾白虾高效健康养殖提供技术支撑。     

Comparative study on nutrient composition and quality evaluation in a new variety and wild‐typed ridgetail white prawn (Exopalaemon carinicauda)

Kesuhong No. 1 with high concentration of astaxanthin was a newly approved aquaculture variety of ridgetail white prawn (Exopalaemon carinicauda) in China, and the information on the nutrient composition and quality evaluation of this new variety is insufficient. Thus, the proximate composition, amino acid and fatty acid profiles were analysed and compared between the new variety and the wild‐typed prawn in the present study, for its better application of the new variety. It showed that there were no significant differences (p > 0.05) of the proximate composition, essential amino acid and saturated fatty acid (SFA) of muscle tissue between the wild‐typed prawn and the new variety. However, for the content of some delicious amino acids (Ala and Tyr), it was significantly higher (p < 0.05) than that in the wild‐typed prawn. Similarly, for some ω3 polyunsaturated fatty acids (ω3 PUFA), such as docosahexaenoic acid (DHA) and eicosapntemacnioc acid (EPA), it was also significantly higher (p < 0.05) than that in the wild‐typed prawn. In addition, higher PUFA/SFA ratio and lower ω6/ω3 ratio also improved muscle quality in the new variety. Information obtained in the present study indicates a promising natural source of ω3 PUFA with high nutritional value, and has strong potential application value in this new variety of E. carinicauda.     

Identification of potential general markers of disease resistance in Exopalaemon carinicauda via three‐round challenge selection with an acute hepatopancreatic necrosis disease‐causing strain of Vibrio parahaemolyticus

Sixteen candidate disease‐resistant parameters were selected through which to evaluate the acute hepatopancreatic necrosis disease (AHPND)‐resistant capability of Exopalaemon carinicauda after three generations of selection for AHPND‐causing strain of Vibrio parahaemolyticus (VP_AHPND) resistance in our previous study. However, these parameters required further verification. In this study, another AHPND‐resistant E. carinicauda series was obtained through a short‐term selection procedure, consisting of three virulent challenge rounds of selection (about three‐week interval for each challenge) with VP_AHPND infection. After this selection, the survival rate at 144 hr post infection (hpi) increased from 23.33% to 37.78% and the observed 48‐hr LD₅₀ of VP_AHPND to shrimp increased from 10^5.5 cfu/ml to 10^6.5 cfu/ml. Then, the immune response of this AHPND‐resistant E. carinicauda was studied using the 16 candidate AHPND‐resistant parameters selected for in our previous study. The improved VP_AHPND clearance rate in hpi, increased total haemocyte counts, haemocyanin concentration, alkaline phosphatase activity and expressions of six immune‐related genes (Tollip and ALF in haemocytes and hepatopancreas; lysozyme, crustin and cathepsin B in hepatopancreas; and LGBP in haemocytes) at 24 hpi after the three‐round challenge selection suggest that these immune parameters may be reliable markers for the evaluation of the physiological status and potential AHPND‐resistant phenotypes in E. carinicauda.     

不同生物饵料组合对脊尾白虾幼体变态发育的影响

本研究以脊尾白虾(Exopalaemon carinicauda)幼体为研究对象,研究了牟氏角毛藻(Chaeroeeros moelleri)、褶皱臂尾轮虫(Brachionus plicatilis)和卤虫(Artemia salina)无节幼体搭配投喂对脊尾白虾幼体的存活率(SR)、变态发育和消化酶的影响。结果显示,单一卤虫组的幼体变态发育速度最快,14 d内全部变态为仔虾,其他3组则需要15 d;单一卤虫组、牟氏角毛藻+卤虫组和轮虫+卤虫组的幼体变态为仔虾时的SR分别为84.33%、84.67%和83.00%,各组间差异不显著(P>0.05);投喂牟氏角毛藻+轮虫+卤虫混合饵料组的幼体在Z5~P阶段大量死亡,变态为仔虾时的SR为35.67%。单一卤虫组投喂的脊尾白虾幼体的胃蛋白酶(1.94 U/mg prot)、脂肪酶(2.35 U/mg prot)和α-淀粉酶(0.13 U/mg prot)活力在4个组中最高,牟氏角毛藻+轮虫+卤虫组的胃蛋白酶(0.08 U/mg prot)、脂肪酶(0.91 U/mg prot)和α-淀粉酶(0.08 U/mg prot)活力在4个组中最低;牟氏角毛藻+卤虫组和轮虫+卤虫组的α-淀粉酶活力均为0.12 U/mg prot,而轮虫+卤虫组幼体的脂肪酶(1.78 U/mg prot)和胃蛋白酶(0.39 U/mg prot)比牟氏角毛藻+卤虫组分别高0.35和0.04 U/mg prot。研究表明,在脊尾白虾育苗过程中,投喂卤虫无节幼体(3~5 ind./mL),能提高幼体SR和加快变态发育速度,同时,在养殖过程中加入一定的牟氏角毛藻可减缓养殖水体恶化的速度。     

脊尾白虾早期胚胎发育以及温、盐度与其孵化的关系

本文对脊尾白虾的早期胚胎发育进行了详细地描述,并对温、盐度及其孵化的关系进行了研究。结果表明:在水温22.8—27.5℃、盐度31.60—31.70‰的条件下,脊尾白虾的早期胚胎发育可划分为12个发育期,整个发育过程约需10-11天;在实验温、盐度内,孵化时数与温度成负相关,与盐度成正相关。     

虾肝肠胞虫感染对脊尾白虾肠道菌群的影响

为探究虾肝肠胞虫(Enterocytozoon hepatopenaei, EHP)感染对脊尾白虾(Exopalaemon carinicauda)肠道菌群的影响,本研究基于16S rRNA基因的测序结果,对感染EHP的脊尾白虾肠道菌群进行了分析。结果显示,感染虾与健康虾肠道菌群差异较大,且其肠道菌群结构多样性显著低于健康虾。研究发现,病虾中归属于变形菌门(Proteobacteria)的脱硫弧菌科(Desulfovibrionaceae)、弧菌科(Vibrionaceae)、未分类蓝细菌科(unidentified Cyanobacteria)、支原体科(Mycoplasmataceae)和未分类α变形菌科(unidentified Alphaproteobacteria)为优势菌,而归属于厚壁菌门(Firmicutes)的乳杆菌科(Lactobacillaceae)、双歧杆菌科(Bifidobacteriaceae)、芽孢杆菌科(Bacillaceae)及噬几丁质杆菌科(Chitinophagaceae)细菌在健康虾中占据优势地位。EHP侵蚀导致感染虾肠道内潜在致病菌显著增加(P<0.05),增加了其他疾病的易感性。此外,通过Tax4Fun功能预测,发现感染虾肠道菌群主要用于新陈代谢,从而抵抗EHP侵染,维持机体正常功能;健康虾肠道菌群则多用于个体生长与环境信息处理,进而保证生长与存活。本研究从虾肠道菌群结构方面入手,进一步探究了EHP感染对脊尾白虾肠道菌群的影响,以期为EHP的防治提供帮助。     

3种肉食性鱼类的捕食及脊尾白虾防御行为比较

通过对黑鲷、漠斑牙鲆及暗纹东方鲀3种肉食性鱼类捕食脊尾白虾的行为观察。结果发现,3种肉食性鱼捕食脊尾白虾的强度排列依次为黑鲷暗纹东方鲀漠斑牙鲆。脊尾白虾最主要的防御方式为尾扇拨水向后弹开。     

不同温度对脊尾白虾胚胎发育与幼体变态存活的影响

选用实验室内人工控制交尾的脊尾白虾,研究了不同温度对脊尾白虾胚胎发育及幼体变态、存活的影响.结果表明,在盐度为31的条件下,脊尾白虾胚胎发育的生物学零度为12.18℃,有效积温为3828.27℃·h.在15.3-28.1℃范围内,胚胎发育时间随着温度升高而呈双曲线性缩短,而胚胎发育速度随着温度的升高而呈直线性加快,但当温度超过30℃时,胚胎无法正常完成发育.脊尾白虾幼体变态发育速度随着温度的升高而加快,18、20、22、24、26、28℃各实验组开始出现仔虾的时间依次为17、14、11、9、8和8d,各组90％以上幼体变态为仔虾的时间依次为21、18、15、14、11和11d.各实验组在幼体变态过程中存活率都呈明显的阶梯式下降趋势,且28℃组的存活率下降最快,但当存活幼体全部变为仔虾时,各实验组间的存活率并无显著性差异(P＞0.05).18℃组仔虾干质量明显高于其它各组(P＜0.05),28℃组仔虾干质量最低,但与20、22、24、26℃组无显著性差异(P＞0.05).因此在脊尾白虾育苗中,幼体孵化温度不应低于12℃,最高不超过28℃为宜;幼体培育温度,建议控制在22-26℃为最佳.     

饲料蛋白水平对池塘养殖脊尾白虾生长、生理指标和体组成的影响

【目的】探究池塘养殖脊尾白虾的饲料适宜蛋白水平。【方法】在12个长14 m×宽12 m×深1.2 m的水泥池中各放入1 kg规格接近（平均2.5 g/尾）的脊尾白虾（Exopalaemon carinicauda）亲本，数量400尾，雌雄各半，每3个水泥池作为一个处理，分别投喂蛋白水平为30%、34%、38%和42%的配合饲料（1#~4#饲料组）。养殖周期为4个月，测定各饲料组脊尾白虾的体质量、肝胰腺指数（HSI）、出肉率和生理生化指标。【结果】（1）各饲料组之间脊尾白虾的体质量、肝胰腺和出肉率均无显著性差异，其中2#饲料组的体质量和HSI略高于其他组。（2）各饲料组肝胰腺中谷草转氨酶（GOT）和超氧化物歧化酶（SOD）的活力差异显著，其中3#饲料组GOT活力最低，而2#饲料组SOD活力最高；（3）饲料中的蛋白水平对肝胰腺中灰分含量影响显著，3#饲料组显著高于1#、2#饲料组；（4）饲料蛋白水平对肌肉中粗脂肪和灰分含量存在显著影响，随着饲料中蛋白水平的增加，肌肉中粗脂肪含量呈显著下降趋势，而1#~3#饲料组肌肉中的灰分含量显著上升，其中1#饲料组的粗脂肪、3#饲料组的灰分含量最高。【结论】池塘养殖条件下脊尾白虾饲料最适蛋白水平为34%左右。