大黄鱼(Pseudosciaena crocea)内脏白点病的组织病理和超微病理分析

利用组织切片及超薄切片电镜技术对患内脏白点病大黄鱼(Pseudosciaena crocea)的肝脏、脾脏和肾脏3种组织进行病理学分析,探讨该病的致病机理。结果显示,大黄鱼的临床症状为体表无明显病症,脾、肾、肝等内脏有大量白色结节;组织病理显示,肝、肾和脾是感染损伤的主要靶器官,出现组织变性坏死,空泡化严重,炎性细胞浸润;病变组织均出现病理性结节。超微病理显示,病鱼肝、肾、脾细胞超微结构受损严重,尤以线粒体和细胞核损伤明显。线粒体肿胀,嵴断裂消失,空泡化;细胞核核膜破裂,染色质浓缩边集;肾脏和脾脏均发现大量菌聚集成团的病原。研究表明,大黄鱼内脏白点病的组织细胞病理变化特征显示了病原菌的入侵和危害,造成鱼体生理代谢紊乱,免疫力和抵抗力下降,鱼体终因无法维持正常的生命活动而导致死亡。     

高体鰤类结节病的病理组织学观察

实验使用组织病理学、活体压片和电镜技术,运用H.E常规染色法和美兰染色法对患有疑似类结节病的高体(鰤)进行病理组织学诊断和观察.结果显示,患病高体蛳肾脏和脾脏有大量白色小结节,直径大约1 mm;活体压片,观察到脾脏和肾脏中有散在短杆状细菌和大量呈团块状聚集的细菌结节;光学显微镜下,肾脏和脾脏有大量细菌聚集形成的嗜碱性结节,肾间质淤积的血液中也有大量细菌;透射电镜观察到肾脏和脾脏中有些巨噬细胞在吞噬细菌,有些菌体聚结成团形成结节,未见病毒颗粒.从病变组织中分离到两端极染的革兰氏阴性短杆菌,无鞭毛,长0.8～2.6 μm,宽约0.6～1.2μm.患病高体(鰤)器官主要组织病理学变化有肾小管上皮细胞变性坏死,肾间质淋巴细胞增生;脾淤血和淋巴细胞增生;肝细胞肿胀,脂肪变性.依组织病变、病原形态和特性,患病高体师为类结节病.     

尼罗罗非鱼无乳链球菌病的病理学研究

为了解尼罗罗非鱼感染无乳链球菌后各组织的病理变化,运用革兰氏染色和电镜负染技术对一株从自然发病的尼罗罗非鱼上分离的无乳链球菌进行形态观察,采用组织切片和超薄切片电镜技术对患病尼罗罗非鱼的肝脏、脾脏、肾脏、脑、心肌、骨骼肌、肠、鳃等8种组织进行病理学研究,探讨该病的致病机理。结果显示,革兰氏染色呈阳性,负染后透射电镜观察多数细菌呈链状排列;组织病理学变化主要是各内脏器官的广泛充血、水肿、变性和炎性细胞浸润,严重的细胞坏死;超微病理显示,大量球菌侵染脾脏等内脏组织,破坏细胞结构和各种细胞器;细胞界限模糊,细胞核畸形,线粒体肿大,嵴断裂,溶解;粗面内质网肿大、核糖体脱落;细胞质空泡化严重;心肌和骨骼肌纤维断裂、紊乱、肌节长短不一;肠微绒毛排列不整齐、长短不一;眼中有纤维性沉积。研究表明,无乳链球菌能造成尼罗罗非鱼全身性组织器官损害和炎症反应,尤其是肝脏、脾脏、肾脏和脑等重要器官功能障碍和衰竭,最后导致鱼体死亡。     

网箱养殖大黄鱼内脏白点病病原菌分离鉴定及致病性研究

为探究宁德市网箱养殖大黄鱼内脏白点病及其病原菌的致病性,通过宏基因组分析及对比,初步判定内脏白点病病原菌为假单胞菌属细菌。将分离纯化后的菌株ND2018对健康大黄鱼进行腹腔注射回归感染试验,证实菌株ND2018为大黄鱼内脏白点病病原菌。结合菌株ND2018的全基因测序结果,最终确定菌株ND2018为变形假单胞菌。试验结果显示,变形假单胞菌ND2018为条件病原菌,菌液密度高于1×10~4 cfu/mL时,大黄鱼内脏出现白色结节症状,变形假单胞菌ND2018致病性得到体现。对白色结节内脏进行组织病理学观察,结果显示,病鱼的肝脏、脾脏和肾脏组织均发生炎性病变,含铁血黄素沉积,变性或坏死组织细胞与菌体形成肉芽肿组织结节,即为肉眼可见的"白点"。该菌株对新霉素、卡那霉素、呋喃唑酮、环丙沙星、复方磺胺以及多黏菌素B敏感,对恩诺沙星、庆大霉素、氟苯尼考等20种抗生素耐药。本试验结果可为该地区网箱大黄鱼健康养殖和内脏白点病防预及治疗工作提供基础理论参考。     

养殖大黄鱼“白鳃病”一种新病毒病原的初步研究

运用组织病理学、电镜观察及PCR扩增等方法对近年来网箱养殖大黄鱼暴发的"白鳃病"进行了研究,以探讨引起养殖大黄鱼"白鳃"关联病毒的致病机理。临床解剖观察显示:患"白鳃病"的鱼表现出极度的贫血症状、鳃丝苍白色、血液稀薄且血细胞数显著减少;内脏组织病理观察结果显示:鱼的肝、脾、肾脏内脏组织发生严重的病理变化,组织内红细胞发生明显的退行性变化,同时鱼体的红细胞数量显著减少;采用针对真鲷虹彩病毒(red sea bream iridoviral virus,RSIV)的引物对病鱼内脏组织核酸样本进行PCR检测,结果显示,患"白鳃病"病鱼样本RSIV核酸呈阴性;组织超薄切片电镜观察结果显示:在患"白鳃病"病鱼脾脏和肾脏组织细胞的胞质中可见直径约40~45 nm的病毒粒子。由此初步判断,浙江地区网箱养殖大黄鱼的"白鳃病"不是由RSIV导致,而与一种直径为45~50 nm的病毒有直接关联,本研究为大黄鱼疾病的诊断与防治提供了参考依据。     

乌鳢出血性败血症病理组织学初步研究

乌鳢出血性败血症是由嗜水气单胞菌及其产生的毒力因子引起的暴发性疾病。患病乌鳢肝实质结构严重受损,细胞索结构模糊,界限不清;肝细胞肿大,细胞核肿胀,空泡化,肝细胞大面积坏死解体,被染成浅色一片。病鱼肾脏结构也受损,肾单位数量显著减少,肾间质所占比例增大,淋巴细胞增多;肾小囊腔扩大;肾小管肿胀,部分肾小管上皮细胞变性,甚至坏死。脾脏淋巴组织松散,淋巴细胞减少,衰老细胞增多。     

美国红鱼肾肿大症的组织病理研究

2005年11月,浙江省象山县西沪港海水网箱养殖的美国红鱼中发生一种以肾肿大为主要特征的流行性疾病,其体表溃疡、肾脏特别肿大,脾脏、肝脏稍肿,严重者脏器上有白色结节.对该病进行了组织病理学研究,结果显示,肾脏、肝脏、脾脏均有充血、脂肪样变、炎性细胞浸润等症状,并有典型的肉芽肿;心肌细胞、鳃上皮细胞萎缩、坏死.分析了该病的病理过程和致病原因,为美国红鱼肾肿大症的防治提供理论依据.     

患诺卡氏菌病的大黄鱼几种主要组织的酶活力变化分析

以酶学分析方法,测定患诺卡氏菌病的大黄鱼几种主要组织的酶活力变化。结果表明,与对照组相比,患病大黄鱼淀粉酶活力在心、脾中无明显变化,在肾、肝和鳃中均有极显著下降(P<0.01);溶菌酶活力在心、肾、肝、鳃中极显著升高(P<0.01),而在脾脏中极显著下降(P<0.01);碱性磷酸酶活力在心、脾、肝、鳃中明显升高,在肾脏中极显著下降(P<0.01);酸性磷酸酶活力在心、脾中较高,肾、肝中偏低,鳃中无明显变化;谷草转氨酶和谷丙转氨酶活力在肾脏中均极显著升高,肝脏中均极显著降低(P<0.01),而在心、脾、鳃组织中均无明显变化(P>0.05);丙二醛在肾脏和肝脏中含量均有升高,在心、脾、鳃中无明显变化;超氧化物歧化酶活力在肝和鳃中极显著下降(P<0.01),在心、脾、肾中无明显变化;过氧化氢酶活力在心和肾中显著降低,在脾脏中极显著升高(P<0.01),而在肝脏和鳃中无明显变化。由此可见,大黄鱼对诺卡氏菌侵染有明显的应激反应,且病原菌对病鱼器官有不同程度的损伤。     

大黄鱼幼鱼虹彩病毒感染的电镜研究

目的:探索大黄鱼幼鱼夏季高温病流行的病毒性病原体。方法:应用电子显微镜观察大黄鱼幼鱼内脏组织超薄切片。结果:发现大黄鱼幼鱼脾脏细胞肿胀,细胞内存在大量虹彩病毒颗粒。病毒颗粒直径约120nm,呈六角形,有一层蛋白质外壳,核心为核酸。病毒感染主要位于细胞质内。结论:大黄鱼幼鱼脾细胞感染的病毒是虹彩病毒,虹彩病毒感染及环境因素可能是导致大黄鱼幼鱼夏季高温病暴发流行并致死的主要原因。     

南方鲇幼鱼细菌性败血症病原与组织病理

从天然患病南方鲇(Silurus meridionalis Chen)幼鱼的肝脏中分离获得1株优势菌,命名为SCL1.用该菌株人工感染健康南方鲇幼鱼,发现菌株SCL1的感染致死率高,且患病症状与自然发病症状一致.再从人工感染的患病鱼肝脏中分离病原菌,再次感染健康南方鲇幼鱼,其症状与自然发病症状一致,确认分离菌株为南方鲇"败血症"的致病菌.该菌株形态学、生理生化特征和16S rDNA基因序列显示其为嗜水气单胞菌(Aeromonas hydrophila).药敏试验结果表明,该菌对土霉素、链霉素、氧氟沙星、氟哌酸、卡那霉素和庆大霉素高度敏感,而对青霉素钠、麦迪霉素、罗红霉素、甲氧苄啶、乙酞螺旋霉素不敏感.组织病理研究显示患病南方贴肝组织严重坏死,肝细胞排列紊乱,部分肝细胞核肿胀、崩解;脾脏细胞间界限不清,细胞核膨大,核内染色质疏松;肾小管上皮细胞肿胀,肾小囊腔间隙增大,可见该菌主要损伤南方鲇幼鱼肝、肾和脾.本研究旨在为南方站细菌性败血症的诊断与防治提供科学依据.     

海水网箱养殖大黄鱼弧菌病的流行病学研究

2000年5月～2003年11月,采用实地调查、取样及从各县水产技术推广站获取流行病学资料等方法,跟踪调查了浙江省沿海12个海水网箱养殖场大黄鱼弧菌病的发病情况,并对患病濒死大黄鱼进行了病原菌的分离及病理学观察。研究结果表明:该病发病率高、发病范围广,流行时间为6～10月份,7～8月份为高峰期,一般死亡率为30%～40%,最高可达80%以上。主要病原为溶藻弧菌(Vibrioalginolyticus)和哈氏弧菌(V harveyi),可引起大黄鱼肝、肾、脾等组织严重病变。发病原因主要是由于养殖密度过高、养殖环境条件恶化,夏季高温使得弧菌大量繁殖,在鱼体由于各种原因造成损伤时,诱发了疾病的爆发。     

大黄鱼致病嗜水气单胞菌的分离鉴定及其多克隆抗体制备

为探究引起网箱养殖大黄鱼肠炎病的病原及其特性,自患病大黄鱼肝脏组织分离到1株优势菌NDLc-P,经回归感染试验确认该菌为大黄鱼致病菌.人工感染7 d后,该菌对体质量(46.4±3.5)g的健康大黄鱼的半数致死密度为3.98×107 cf u/m L,表明该菌株对大黄鱼有一定的致病性.利用梅里埃微量多项鉴定系统对病原菌N...     

Visceral granulomas in farmed large yellow croaker,Larimichthys crocea (Richardson), caused by a bacterial pathogen,Pseudomonas plecoglossicida

An enzootic disease characterized by granulomas in internal organs occurred in cage‐farmed large yellow croaker, Larimichthys crocea (Richardson), in April and November 2010, in Ningbo, Zhejiang Province. One bacterial strain, named XSDHY‐P, was isolated from the diseased fish and identified by biochemical characterization, fatty acid methyl ester (FAME) analysis and multilocus sequence analysis (MLSA). According to the results obtained from the biochemical tests, FAME analysis and phylogenetic analysis derived from 16S ribosomal RNA, gyrB, oprF, oprI, oprL and rpoD gene sequencing, the bacterial isolate, XSDHY‐P, was identified as Pseudomonas plecoglossicida. Moreover, lethal dose, 50% trials were carried out to demonstrate the virulence of XSDHY‐P in large yellow croaker when administered at 2.13 × 10⁵ colony‐forming units per fish. Visceral granulomas were found in the experimentally infected fish as well as in the naturally infected fish, indicating that P. plecoglossicida is another bacterial pathogen that causes granulomatosis in L. crocea.     

网箱养殖大黄鱼诺卡氏菌病的初步研究

首次报道了大黄鱼诺卡氏菌病的发生情况。病鱼以体表和心、脾、肾等内脏出现白色结节为主要症状，平均死亡率15％。对病鱼进行细菌分离培养和光镜、电镜检查，均发现长或短的丝状分枝状杆菌。用分离菌株作回归感染，证实为该大黄鱼结节病的病原菌。对病原菌的基本生物学特性进行了研究，确定病原为诺卡氏菌。     

An outbreak of visceral white nodules disease caused by Pseudomonas plecoglossicida at a water temperature of 12°C in cultured large yellow croaker (Larimichthys crocea) in China

Visceral white nodules disease (VWND) caused by Pseudomonas plecoglossicida is a common disease in cage-farmed large yellow croaker (Larimichthys crocea) in China. VWND usually occurred at water temperature of 16–19℃, resulting in high mortality in farmed large yellow croaker. Now, P. plecoglossicida as its pathogen has been considered nonpathogenic at 7–12℃. During February 2019, an infectious disease outbreak was observed in cage-farmed large yellow croaker at a water temperature of 12℃ in Ningde, China. This disease is characterized by white granulomatous lesions in internal organs of the diseased fish, which was similar with the symptoms of the VWND in large yellow croaker. Then, we isolated a bacterial strain named PQLYC4 from visceral lesions of the diseased fish. The experimental infection studies demonstrated that the strain PQLYC4 was the pathogen of the disease, which was further identified as P. plecoglossicida by the analysis of morphology, 16s rRNA gene homology and average nucleotide identity based on the whole genome sequence. Our results revealed that P. plecoglossicida strain PQLYC4 could cause the outbreak of the VWND at 12℃, a water temperature lower than that reported previously, thus providing new knowledges of prevalence and prevention of the VWND in large yellow croaker.     

Jaundice disease in the farmed catfish hybrid, Clarias macrocephalus (Gunther) ×C. gariepinus (Burchell), in Thailand

Abstract. In recent years, jaundice disease in farmed hybrid catfish in Thailand has caused high levels of mortalities. Affected fish are lethargic and anorexic and show yellow pigmentation of the skin and gills. Internally, the spleen, kidney and gall bladder are enlarged, and the spleen, kidney, liver and body fat are a pale yellow colour. Most fish contain a yellow ascitic fluid in their abdomen. Histological examination of tissues from diseased fish revealed heavy deposits of haemosiderin and ceroid in the spleen, kidney and liver. Haematological measurements showed that haematocrit values, RBC count, haemoglobin concentration, MCH and MCHC were significantly decreased in affected fish while MCV, total bilirubin and direct reacting bilirubin were significantly increased. The results indicate that the fish are suffering from a haemolytic anaemia associated with lipoid liver degeneration. The disease is thought to be due to the feeding of rancid chicken viscera.     

大黄鱼感染致病弧菌的检测及其病害的预测预警

为预防与控制大黄鱼溃疡病的发生,本研究利用特异多重PCR技术,对象山县养殖大黄鱼的3种致病弧菌感染情况进行了流行病学调查。每月在各定点网箱组随机采集大黄鱼肝、肾、脾、肌肉等组织进行感染情况的检测。结果显示,3种致病弧菌对大黄鱼的感染率存在一定的差异性。溶藻弧菌、哈维弧菌对大黄鱼的感染率整体高于副溶血弧菌;从感染组织分析,与肝脏、肾脏相比3种致病弧菌更易感染肌肉、脾脏;3种致病弧菌对不同鱼龄的大黄鱼感染率各不相同。研究还表明,3种致病弧菌在各个采样时间点均有感染,其中7—9月为弧菌感染高峰期,而台风后的感染率较台风前都有一定提高。另外,根据大黄鱼溃疡病发生与3种致病弧菌感染率关系的研究可知,在大黄鱼溃疡病暴发前几天,弧菌的感染率都会显示出较高数值。因此,可以通过3种致病弧菌对大黄鱼感染的分子流行病学调查与分析来预测预警病害的发生和流行。     

Nocardiosis in large yellow croaker, Larimichthys crocea (Richardson)

An epizootic in seawater-cage reared large yellow croaker, Larimichthys crocea, in China was caused by a Nocardia sp. from August to October 2003. The cumulative mortality rate was 15% and the diseased fish were 16 months old with individual length varying from 25 to 30 cm. Multiple, white nodules, 0.1-0.2 cm in diameter, were scattered on the heart, spleen and kidney. The morphology of isolated bacteria from Lowenstein-Jensen medium and tryptic soy agar was bead-like or long, slender, filamentous rods. Experimental infection indicated that the isolated bacterium was the pathogen responsible for the mortalities. A partial sequence of the 16S rRNA gene of the organism and the type strain of Nocardia seriolae JCM 3360T (Z36925) formed a monophyletic clade with a high sequence similarity of 99.9%. Based on the morphological, physiological, biological properties and the phylogenetic analysis, the pathogenic organism was identified as N. seriolae. This is the first report on N. seriolae-infected large yellow croaker in aquaculture.     

Oral bovine serum albumin immune‐stimulating complexes improve the immune responses and resistance of large yellow croaker (Pseudosciaena crocea,Richardson, 1846) against Vibrio alginolyticus

This study aimed to investigate effects of bovine serum albumin immune‐stimulating complexes (BSA ISCOMs) on immune‐related genes expression, serum nonspecific immunity and disease resistance of large yellow croaker (Pseudosciaena crocea). Fish were fed diets containing 3.5 ml of BSA ISCOMs per kg feed (experimental group) or 3.5 ml of phosphate‐buffered saline per kg feed (control group) for 1 week. The liver, spleen, head‐kidney tissues were sampled for determining gene expression of myxovirus‐resistant protein (Mx), major histocompatibility complex class II alpha chain (MHC II α), tumour necrosis factor‐alpha (TNF‐α) and interleukin‐10 (IL‐10) 30 and 90 days after feeding. Also, blood samples were collected for determining activities of serum superoxide dismutase (SOD), interferon alpha (IFN‐α), TNF‐α and alkaline phosphatase (ALP). TNF‐α and MHCⅡα gene expression in the liver, spleen, head‐kidney, as well as IFN‐α, TNF‐α and ALP activities in the serum, of experimental fish were significantly higher 30 days after feeding; while only TNF‐α and MHC II gene expression in the head‐kidney remained upregulated 90 days after feeding. The cumulative mortality of the experimental fish was significantly lower than control. This study indicated that BSA ISCOMs improved the immune response and induced protective immunity in large yellow croaker.     

The disease status of Australian salmonids: bacteria and bacterial diseases

Abstract. Eleven freshwater salmonid hatcheries in southern Australia were surveyed for bacterial pathogens and diseases between 1981 and 1985, Twenty-five populations of fish were examined in the study, representing a total of 2755 fish, from which kidney, liver, spleen, and in some cases peritoneum, blood and faeces were cultured. Bacteria of pathogenic significance isolated included Aeromonas hvdrophila, Streptococcus sp., Lactobacillus piscicola, Yersinia ruckeri, Mycobacterium fortuitum, M. chelonei and a filamentous acid-fast organism of uncertain taxonomic position. Lacto-bacillus piscicola and Streptococcus sp. were associated with clinical and subclinical peritonitis. Mycobacterium chelonei was isolated from visceral granulomas in an externally normal fish. Aeromonas salmonicida, Renibacterium salmoninarum and Edwardsiella tarda were not isolated, indicating that the diseases furunculosis, bacterial kidney disease and edwardsiellosis are exotic to Australian salmonids. Similarly, while Y. ruckeri was isolated, enteric redmouth disease had not been recorded and is considered an exotic disease.