斑点叉尾鮰病毒焦磷酸测序检测方法的建立

旨在建立一种基于PCR的焦磷酸测序检测方法,用于斑点叉尾鮰病毒病的快速检测和确诊。针对斑点叉尾鮰病毒(CCV)蛋白激酶(PK)基因的保守区域设计扩增引物与测序引物,经PCR扩增后对PCR产物进行焦磷酸测序,借助测序结果比对确定是否为CCV核酸序列。通过对反应条件与体系的优化,成功建立了CCV PK基因焦磷酸测序检测方法。结果表明:建立的斑点叉尾鮰病毒焦磷酸测序检测方法扩增基因片段长度为144 bp,能够特异性检测出目的病毒,最低核酸检测限为5×10-6ng/μL,重复测序3次均能准确测出45 bp核酸序列。本研究建立的斑点叉尾鮰病毒焦磷酸测序检测方法特异性强、灵敏度高、重复性好,适合高通量检测且耗时短仅需4 h,为CCV的快速检测提供了一种可行方法。     

常用鱼药的正确安全使用

1敌百虫:虾蟹、淡水白鲳、鳜禁用;加州鲈、乌鳢、鲶、大口鲶、斑点叉尾鱼回、鳜、虹鳟、海水章鱼、胡子鲶、宝石鲈慎用。2高锰酸钾:斑点叉尾鱼回、大口鲶慎用。阳离子表面活性消毒剂:如果用于软体水生动物,轻者会影响生长,重者会造成死亡。海参不得使用。     

不同蛋白及喷浆玉米皮水平对斑点叉尾鮰生长性能、体色及肠道健康的影响

为精确斑点叉尾鮰蛋白需求量及其饲料中喷浆玉米皮的添加量,试验以初始体重（50.0±0.2）g的斑点叉尾鮰作为试验对象,在基础饲料上添加0%（对照组,CON组）、3%(CG3组)、6%(CG6组)和9%(CG9组)的喷浆玉米皮配制成蛋白含量依次为34%、35%、33%、32%的四种饲料,研究其对斑点叉尾鮰（Ictalurus punctatus）生长、体色及肠道健康的影响,每组5个重复,每个重复50尾,试验持续8周。结果表明：各组间斑点叉尾鮰增重率无显著差异（P>0.05）。与对照组相比,CG3、CG6、CG9组斑点叉尾鮰腹脂率显著降低（P <0.05）,但CG3、CG6、CG9组斑点叉尾鮰背部肌肉b*值均显著提高（P <0.05）;CON、CG3组斑点叉尾鮰肠道肌层厚度显著高于CG6、CG9组（P <0.05）;各组间斑点叉尾鮰肠道优势菌门均为梭杆菌门、拟杆菌门、厚壁菌门和变形菌门,与对照组相比,CG9组使斑点叉尾鮰肠道梭杆菌门、厚壁菌门相对丰度下降,变形菌门相对丰度上升。综上所述,在本试验条件下,饲料中添加喷浆玉米皮低于9%（粗蛋白质水平32%）时不影响班点叉...     

斑点叉尾鮰暴发性死亡征病原菌的分离鉴定及药敏试验

为查明广西田东县平马镇小龙村某养殖户网箱养殖的斑点叉尾鮰暴发性死亡征的病原菌及其耐药性。以常规方法分离细菌,人工感染确定病原菌,API全自动细菌鉴定仪对细菌进行生化鉴定,药敏试验为K-B纸片扩散法。结果,从患暴发性死亡征的斑点叉尾鮰中分离到2株病原菌,对斑点叉尾鮰的致死率为100%,API生化鉴定结果,2株病原菌均为温和气单胞菌。药敏试验结果,2株病原菌对24种试验药物中均高度敏感的有复达欣、多粘菌素B等10种,都不敏感的药物有青霉素G和氨苄青霉素2种。     

三都自治县流水养殖斑点叉尾鮰试验

为了探索斑点叉尾鮰的健康养殖模式,促进三都水族自治县渔业产业化发展,2019—2020年依托都柳江优质水资源,采用叉尾鮰膨化配合饲料进行斑点叉尾鮰流水养殖试验。结果:经过128 d饲养后平均体重从500 g生长到1550 g。2019年总产量203230 kg,饵料系数1.7,获利47万余元。试验结果表明,设计合理的养殖模式,采用优质饲料是实现斑点叉尾鮰健康养殖,获得良好经济效益的关键。     

不同胆碱水平对斑点叉尾鮰幼鱼生产性能的影响

以酪蛋白为蛋白源,鱼油和花生油(1∶1)为脂肪源,糊精做糖源,统糠做填充物,α-淀粉为粘合剂,氯化胆碱为胆碱源,加入适量的鱼用维生素和微量矿物质,配制成胆碱含量分别为0.00%、0.20%、0.40%和0.60%的4种饲料,饲喂平均体重6.86±0.11g的斑点叉尾鮰幼鱼。经49d的试验,结果表明,胆碱对斑点叉尾鮰幼鱼生产性能有显著的影响。其中以饲料的胆碱含量为0.20%时饲养效果最好,斑点叉尾鮰幼鱼的增重率和生长比率最高,饵料系数最低。     

一株虾源蜡样芽胞杆菌D7作为潜在益生菌的毒理学研究

为评价一株虾源潜在益生菌蜡样芽胞杆菌D7的毒理安全性,分别从溶血试验、抗菌药物敏感试验、斑点叉尾鮰急性毒性试验、凡纳滨对虾急性毒性试验、破损皮肤刺激性试验、急性眼刺激试验和急性腹腔注射试验等7个指标进行了测试。采用血琼脂平板法测定溶血性,纸片扩散法测试药物的敏感性。采用浸浴和注射两种方式在斑点叉尾鮰上进行急性毒性试验,采用注射方式在凡纳滨对虾进行急性毒性试验。破损皮肤刺激性试验、急性眼刺激试验用家兔,急性腹腔注射性试验用小鼠。结果表明,D7菌株具有明显溶血性,对13种抗菌药物中的9种敏感,104CFU/mL～108CFU/mL浓度下浸浴斑点叉尾鮰,96h内未出现不良症状及死亡,96hLC50108 CFU/mL。以1×109CFU/mL注射斑点叉尾鮰,24h后出现感染死亡,14d内部分试验组出现感染症状,死亡9尾,肝脏是该菌株感染的靶器官。以1×106CFU/mL注射凡纳滨对虾,96h累积死亡率同对照组差异不显著(P0.05)。对家兔急性眼刺激中,该菌株属于无刺激性级别,皮肤刺激试验中,该菌株属于轻刺激性级别,急性腹腔注射,发现该菌株属于强致病性级别。说明虾源蜡样芽胞杆菌D7对养殖鱼类具有一定的毒性,对凡纳滨对虾较为安全。     

植酸酶对斑点叉尾鮰生长性能、营养物质表观消化率及氮、磷排泄的影响

本试验旨在研究植酸酶对斑点叉尾鮰生长性能、营养物质表观消化率及氮、磷排泄的影响,以确定植酸酶在斑点叉尾鮰饲料中的适宜添加量.选取初始均重为(1.74±0.02)g的斑点叉尾鮰幼鱼540尾,随机分成6个组,每组3个重复,每个重复放养30尾鱼.对照组饲喂基础饲料,试验组分别饲喂在基础饲料中添加300、500、1 000、l...     

国产鱼粉替代进口鱼粉对斑点叉尾(鮰)生长的影响

以国产鱼粉替代进口鱼粉,设计2种等蛋白且等能量的配合饲料,投喂斑点叉尾(鮰)进行饲养对比试验,经过55 d的饲养,试验组和对照组(分别投喂A料和B料)的尾相对增重率分别为150.4％和148.5％,尾平均日增质量分别为3.12和3.07 g,饲料系数分别为1.52和1.51,斑点叉尾(鮰)增质量1kg所需饲料成本分别为4.79和5.21元.试验组和对照组斑点叉尾(鮰)肌肉粗蛋白和粗脂肪含量差异不显著,丰满度和内脏比差异也不显著.通过配方调整,国产鱼粉可替代进口鱼粉而不影响斑点叉尾(鮰)的生长速度、饲料效率和肉质.     

斑点叉尾鮰中一种病原菌的分离与鉴定

目的未知病菌对江苏地区斑点叉尾鮰的养殖业造成了巨大的危害,本文对该地区某养殖场病鱼中分离的细菌进行了鉴定及微生物学特性研究。方法采用VIA培养基分离优势菌株;采用回归感染实验确认病原菌;采用形态学观察、生理生化特征测定、细菌特异性引物PCR扩增检测及细菌基因测序分析鉴定细菌;采用药敏实验测定它对部分抗生素的敏感性。结果从病鱼症状及菌株的培养特性、形态特征与嗜麦芽寡养单胞菌感染斑点叉尾鮰症状十分相似,病鱼有典型的肠套叠和肝脏变性现象。分离菌株为革兰氏阴性杆菌,氧化酶阴性、硝酸还原阴性,不发酵糖类,无动力。最初判为嗜麦芽寡养单胞菌,而经过VITEK2生化及16S rRNA基因系统发育进化显示,与不动杆菌16S rRNA核苷酸同源性最高,为98.7%～99.8%,该菌株为约翰逊不动杆菌。结论分离出的约翰逊不动杆菌grp2580083能导致斑点叉尾鮰患病,症状与嗜麦芽寡养单胞菌感染具有类似性,对渔业养殖造成影响。     

Detection of salmonellae from fish in a natural river system

Sediment, water, and fish gut samples taken at three sites near the headwaters of the San Marcos River, Texas, were analyzed for salmonellae Salmonella spp. by culture and molecular techniques. While enrichment cultures from sediment and water samples from the two uppermost sites were negative for salmonellae in polymerase chain reaction analyses, both sediment and water samples were positive at the downstream site. At all sites, salmonellae were present in the guts of different fishes (e.g., largemouth bass Micropterus salmoides, channel catfish Ictalurus punctatus, common carp Cyprinus carpio, and suckermouth catfish Hypostomus plecostomus). The highest percentage of detection (33% of analyzed fish) occurred at the downstream site, whereas detection percentages at the upper two sites were 18% and 17%. Detection of salmonellae was usually limited to one segment of the gut (i.e., upper or lower part). Serovars were highly variable among individuals and differed between the upper and lower gut in the only individual (a common carp) that had salmonellae in both gut segments. In situ hybridization demonstrated that salmonellae were normally associated with particulate material in the gut and occurred in highly variable numbers ranging from an occasional organism to a majority of the gut microbe population. These results demonstrate the presence of different serovars of potentially human pathogenic salmonellae among four ecologically distinct fishes within natural environments. They also suggest that salmonellae are not components of the indigenous microbial community in fish intestines but rather are ingested with particulate material.     

Enhanced susceptibility of channel catfish to the bacterium Edwardsiella ictaluri after parasitism by Ichthyophthirius multifiliis

Bacterium Edwardsiella ictaluri and parasite Ichthyophthirius multifiliis (Ich) are two common pathogens of cultured fish. The objective of this study was to evaluate the susceptibility of channel catfish Ictalurus punctatus to E. ictaluri and determine bacterial loads in different fish organs after parasitism by Ich. Fish received the following treatments: (1) infected by I. multifiliis at 5000 theronts/fish and exposed to E. ictaluri; (2) infected by I. multifiliis alone; (3) exposed to E. ictaluri alone; and (4) non-infected control. E. ictaluri in fish organs were quantified by quantitative real-time polymerase chain reaction and reported as genome equivalents per mg of tissue (GEs/mg). The results demonstrated that the Ich-parasitized catfish showed significantly (P<0.05) higher mortality (91.7%) when exposed to E. ictaluri than non-parasitized fish (10%). The bacterial loads in fish infected by 5000 theronts/fish ranged from 6497 to 163,898 GEs/mg which was between 40 and 2000 fold higher than non-parasitized fish (49-141 GEs/mg). Ich infection enhanced the susceptibility of channel catfish to bacterial invasion and increased fish mortality.     

Trout mortalities as a result of Streptococcus infection.

Excessive mortalities were experienced in the bigger rainbow trout (Salmo gairdneri) at an efficiently managed trout farm. All tests for known toxins in the feed and water proved to be negative. A faecal Streptococcus which belongs to the Lancefield group D but which could not be identified as belonging to any of the recognized species within this group, was isolated from the spleens, livers and kidneys of affected fish. Pathogenicity studies with this organism proved it to be highly fatal to trout but not to Mozambique bream (Sarotherodon mossambicus), banded bream (Tilapia sparrmenii), carp (Cyprinus carpio) or largemouth bass (Micropterus salmoides). The isolation and biochemical characteristics of the organism are described. The symptoms, gross- and histopathology of this disease are described and discussed. The disease resembles a haemorrhagic septicaemia and appears to be associated with intensification and conditions of stress.     

Differences between the European carp (Cyprinus carpio carpio) and the coloured carp (Cyprinus carpio haematopterus) in susceptibility to Thelohanellus nikolskii (Myxosporea) infection

Thelohanellus nikolskii infection of the common carp (Cyprinus carpio L.) has been a common parasitosis in the Central European fish farms since the first detection of the parasite about 20 years ago. This parasite, introduced from the Far East, causes intensive infection on the fins of fingerlings of the carp subspecies cultured in Europe (European carp, Cyprinus carpio carpio). This infection of the common carp occurs in the Hungarian fish farms every year. Until the present study, this parasite had not been recorded from the fins of koi or coloured carp (Cyprinus carpio haematopterus), a carp of Far Eastern origin, which is cultured in Hungary as an ornamental fish. A recent survey conducted in common carp, koi and goldfish stocks demonstrated that T. nikolskii infection of low prevalence and intensity occurs also in koi populations, but its prevalence and intensity are markedly lower than in common carp kept in the same ponds. It is suggested that the observed differences are due to disparities in the susceptibility of the two carp subspecies to T. nikolskii, and that the koi is less susceptible to this infection. Other signs of susceptibility can also be observed in the European subspecies, since in 15% of the fish plasmodium development was arrested at an early stage. Thelohanellus nikolskii infection could not be demonstrated on goldfish (Carassius auratus).     

The Lethal Dose of Largemouth Bass Virus in Juvenile Largemouth Bass and the Comparative Susceptibility of Striped Bass

Abstract

Largemouth bass virus (LMBV) is an iridovirus that was isolated from wild adult largemouth bass Micropterus salmoides in the southeastern United States in 1994. Although originally isolated from moribund wild fish, its virulence to juvenile largemouth bass is uncertain. To help clarify this point, two LMBV titrations were made in juvenile largemouth bass. Titers of LMBV in fathead minnow cells were 10^4.8 and 10^5.8 tissue culture infectious doses—50% cytopathic endpoint (TCID50) per milliliter, respectively. Tenfold serial dilutions of LMBV employed in each cell culture titration, injected intraperitoneally (0.1 mL/fish) into largemouth bass produced calculated lethal dose—50% mortality endpoints (LD50s) of 282 (10^2.45) and 288 (10^2.46) infectious doses in two consecutive infectivity trials. Virus yield of assayed infected fish averaged 10^8.5 TCID50/g and 10^7.7 TCID50/g in viscera of moribund and dead fish in the two trials and 10^6.5 TCID50/g in surviving exposed fish 14 d after infection. In a second experiment, largemouth bass had 100% mortality 5 d after injection while virus immersed fish had a significantly (P ≤ 0.005) lower mortality of 17% at 14 d. Similarly treated juvenile striped bass Morone saxatilis suffered 63% mortality after injection and significantly (P ≤ 0.005) lower mortality of 10% after immersion. In a third study of 25 d, 100% of injected largemouth bass died by 5 d after injection, and all of them were virus-positive. Injected striped bass had a significantly (P ≤ 0.005) lower mortality of 24%; all three fish were virus-positive initially, two fish were virus-positive at 18 d, and none were positive at 25 d. Juvenile largemouth bass were highly susceptible to LMBV injection and striped bass were moderately susceptible, but both species were only mildly susceptible when exposed by immersion.     

斑点叉尾鮰源致病性维氏气单胞菌的分离与生物学特性鉴定

为鉴定一起致斑点叉尾鮰突然发病死亡的病原，本研究从发病斑点叉尾鮰中分离到1株致病菌GZTL2017，通过临床解剖观察、细菌分离培养、革兰氏染色镜检、动物回归试验、生化试验、16S rDNA序列分析、部分毒力基因检测和药敏试验进行鉴定。临床解剖观察结果显示，患病斑点叉尾鮰呈现体表溃疡、鳍根部出血、烂腮、肠管充血等症状；分离菌在培养基中呈现表面湿润凸起、边缘光滑半透明、形态均一的乳白色菌落；革兰氏染色镜检显示，分离菌为单个或成双存在、两端钝圆的短直阴性杆菌；动物回归试验显示，该分离菌有较强的致病性；生化试验结果显示，分离菌具有运动性，且氧化酶、V-P、赖氨酸脱氢酶等反应阳性，精氨酸双水解酶、硫化氢等反应阴性；16S rDNA基因序列系统进化树显示，该菌与维氏气单胞菌聚为一支，同源性均>99%；毒力基因检测结果显示，该菌能检出气溶素基因（Aer）、黏附素基因（Aha）、外膜蛋白基因（OmpA）3种毒力基因；药敏试验结果显示，该菌对氟苯尼考、强力霉素、氧氟沙星等14种药物敏感；对诺氟沙星、新霉素、万古霉素等7种药物中度敏感；对麦迪霉素、苯唑西林、头孢拉定等8种药物耐药，且对氟苯尼考、强力霉素的药物最小抑菌浓度分别为1和2 μg/mL。本试验成功分离到1株维氏气单胞菌，为斑点叉尾鮰维氏气单胞菌病防治提供参考依据。     

Preliminary Studies of a Newly Developed Subunit Vaccine for Channel Catfish Virus Disease

Abstract

The soluble channel catfish virus (CCV) envelope was harvested and used as a vaccine for channel catfish virus disease. Three- to four-day-old eggs of channel catfish Ictalurus punctatus and 1-week-old fry were vaccinated by immersion. A booster was given to subgroups of fry 2 weeks after vaccination. Vaccinated and nonvaccinated control groups were challenged with viable CCV 8 weeks after vaccination. All challenged nonvaccinated control fry died during the first experiment, and 56% died in the second experiment. Survival offish vaccinated as eggs or fry was 31 and 82%, respectively; survival of groups given a booster dose was 81 and 89%, respectively.     

羊角拗苷不同剂型灭螺活性观察

为了解羊角拗的灭螺活性,用有机溶剂提取、硅胶柱层析分离羊角拗苷化合物,以同一剂量将其制成溶液、颗粒、粉剂,并用浸泡、投喂、喷粉等方法对比处理钉螺。结果显示,羊角拗苷杀螺效果极显著(P<0.01),在室温(25±1)℃、水温(23±1)℃条件下,72 h内3种方法处理的钉螺死亡率均达到90%以上,其中颗粒剂灭螺活性最强,喷粉灭螺优于浸泡灭螺。     

南方大口鲶微卫星标记在怀头鲶群体中适用性研究

本研究分析了31对南方大口鲶（Silurus meriaionalis）微卫星标记引物在怀头鲶（Silurus soldatovi）群体中的适用性。结果表明,南方大口鲶微卫星标记引物在怀头群体中具有较高的适用性,共筛选出可以稳定扩增的微卫星标记15对,每个位点等位基因数为1～5个不等;不同重复拷贝类别的位点以富含AC重复单元的等位基因数较多,多态性比较丰富。借用已有的遗传标记资源,增加同目鱼类遗传连锁图谱上遗传标记的密度,将对今后开展怀头鲶种质资源保护及分子育种奠定坚实基础。     

Ecological studies of helminth parasites of the largemouth bass, Micropterus salmoides, from Lake Naivasha and the Oloidien Bay, Kenya.

The parasites of 541 largemouth bass, Micropterus salmoides, were studied over a period of 12 months. The results showed that the bass from Lake Naivasha are paratenic hosts of Contracaecum sp. larva and final hosts for the acanthocephalan Polyacanthorhynchus kenyensis. The nematode occurred in large numbers in fish caught in the more saline Oloidien Bay but only in small numbers in those in the main lake. Bass in the main lake, however, were more heavily infected with acanthocephalans than those in Oloidien Bay. One of the major pathological effects of the acanthocephalan was perforation of the liver by the spiny proboscis. Seasonal variation was not apparent for either of the parasites. The intensity of infection by Contracaecum sp. larva increased with the size of the host and female fish were more heavily infected than males.