大口黑鲈致死性结节病病原的分离、鉴定及组织病理学观察

2018年4月四川邛崃地区某养殖场大口黑鲈感染致死性结节病,死亡率高达80%。为明确病因,通过常规微生物分离、鉴定,从患病鱼皮肤溃疡灶、鱼鳔腔积液和肝脏组织中分离到同一株优势菌,命名为HSY-NS02。经菌体形态观察、革兰氏染色和抗酸染色镜检、生理生化实验、16S rDNA序列扩增及系统发育分析和特异性PCR扩增,确定该菌为诺卡氏菌。进一步对健康大口黑鲈进行分离菌的人工感染实验以确定其致病性,结果显示,人工感染鱼出现与自然发病相似症状,且从人工感染鱼体中再次分离到相同菌。组织病理学观察显示,皮肤溃疡灶、心脏、肝脏、脾脏、肾脏和鳃发生不同程度的慢性炎性肉芽肿病变,其中脾脏病变最为严重。对菌株HSY-NS02进行药物敏感性实验,结果显示,该菌对庆大霉素、新霉素和制霉菌素3种药物敏感,对其他18种药物耐受,呈多重耐药性。     

Experimental susceptibility of different life-stages of the giant freshwater prawn, Macrobrachium rosenbergii (de Man), to white spot syndrome virus (WSSV)

Studies were conducted by injecting/feeding white spot syndrome virus (WSSV) derived from infected shrimp, Penaeus monodon (Fabricius), to different life-stages, namely post-larvae, juveniles, sub-adults and adults of Macrobrachium rosenbergii (de Man). The disease was also induced in brood stock, and the eggs and larvae derived from these animals were subsequently tested for WSSV infection. All the stages except egg used for the experiment were found WSSV positive in histopathology, cross infection bioassay and polymerase chain reaction (PCR) analysis. Experimentally infected post-larvae and juveniles showed a high percentage of mortality and an increased rate of cannibalism. The cumulative mortality in post-larvae was up to 28%; with 28–40% cannibalism resulting in a maximum loss of up to 68%. In juveniles, observed mortality and cannibalism were 10–20% and 6.7–30.0%, respectively, and the maximum loss recorded was 50%. In sub-adults, mortality ranged from 2.8 to 6.7%, cannibalism was up to 20% and the total loss was up to 26.7%. Sub-adults and adults were found to be more tolerant to the infection as evidenced by the mortality pattern. A nested (two-step) PCR resulted in a 570-bp product specific to WSSV in all stages, except the eggs.     

乌鳢诺卡氏菌病的组织病理学

应用病理组织学、活体压片和电镜技术,运用H.E常规染色法和Ziehl-Neelsen抗酸杆菌染色法对患疑似诺卡氏菌病的乌鳢各器官进行观察.结果表明,患病乌鳢的肾脏、肝脏、头肾、脾脏、肌肉、表皮、鳃丝、鳃弓、心脏、肠道、卵巢等器官内部有大量的慢性肉芽肿结节,直径多为1～2 mm.典型结节基本结构可分三层,由内向外依次为:干酪样坏死、类上皮细胞和多核巨细胞、成纤维细胞和纤维细胞包膜,中央干酪样坏死组织中有大量呈长杆状或分枝状的诺卡氏菌.结节活体压片观察到大量的长杆状或分枝状菌体.电镜观察到结节中有大量杆状菌体,未见病毒颗粒;菌体长3.5～6.5 μm,宽0.45～6.8 μm.器官主要组织病理学变化为:肾小管细胞变性和坏死,肾间质淋巴细胞增生;脾淋巴细胞增生和淤血;肝脂肪变性;鳃上皮肿胀,鳃丝棒状化;心肌细胞肿胀,断裂,溶解;肌纤维水泡变性,肿胀,断裂,溶解,坏死;表皮细胞变性,坏死,脱落,有炎性细胞浸润,诺卡氏菌对机体的主要器官造成严重病理损伤.对乌鳢诺卡氏菌病的组织病理变化进行了较为系统的研究,可为临床诊断和相关研究提供参考依据.     

Toxic effects of indoxacarb on gill and kidney histopathology and biochemical indicators in common carp (Cyprinus carpio)

The aim of this study was to determine the biochemical and histopathological effects of indoxacarb on an economic fish species Cyprinus carpio. The fish were divided into four triplicated groups exposed to either of 0% (control), 5% (0.75 mg/L), 10% (1.5 mg/L) or 20% (3 mg/L) of the pesticide LC₅₀. Blood sampling was performed after 7, 14 and 21 days exposure. There were no changes in blood calcium levels at any times. In the indoxacarb‐treated fish, chloride levels decreased at the first and increased at the second sampling compared to the control. In 3 mg/L treatment, phosphorus increased significantly after 7 days compared to the control. Plasma glucose levels decreased significantly at the 7th and 14th days sampling; however, it increased at the 21st day. After 7 days, creatinine level in 3 mg/L treatment was significantly lower than the control; however, the creatinine levels of indoxacarb treatments were higher than the control at the 21st day. The indoxacarb‐treated fish had higher plasma urea levels compared to the control at the 7th day. At the 21st day, plasma urea level at 3 mg/L was significantly lower than the control treatment. Edema, Lamellar curling, hyperplasia, lamellar fusion and hyperaemia were observed in the indoxacarb‐treated fish gill. Tubular necrosis, hematopoietic necrosis, melanomacrophage aggregates, Bowman's capsule edema, glomerulus degeneration and hyperaemia were observed in the indoxacarb‐treated fish kidney. Generally, sublethal concentrations of indoxacarb cause stress, hydromineral imbalance, metabolism alteration and gill and kidney damages in common carp.     

无锡市河埒口高产鱼池水质研究 Ⅰ.水化学和初级生产力

本文总结了1977年5—8月对无锡河埒口高产池塘水化学研究的成果。该地区高产池主要离子含量适中,pH稳定。有效氮含量平均1.38毫克/升,其中铵氮占61％,亚硝酸氮占14％,硝酸氮占 25％。溶解活性磷(P_2O_5)平均为 0.028毫克/升。N/P 为 61—139。COD_(Mn)为 13.3毫克/升。磷是初级生产力的限制因素。 经初步分析表明:池水中溶解有机物与悬浮有机物约各占一半,而有机碎屑占有机悬浮物的 2/3到 4/5。平均补偿深度 77—80厘米,为平均透明度的 2.4倍。5—8月间平均水柱日初级毛生产量为9.41—10.09克氧/米~2·日。池水氧气的消耗,池鱼约占20％,“水呼吸”约占70％,底质约占 10％。氧气来源约 60％靠光合作用,40％靠空气溶解。     

大黄鱼感染哈维氏弧菌后血液生化指标的变化及组织病理学观察

从患病大黄鱼病灶中分离出病原哈维氏弧菌,并人工回接感染大黄鱼,病鱼出现典型的皮肤溃疡症。测定大黄鱼血液各项指标发现,病鱼单核细胞、嗜中性粒细胞、血栓细胞百分率明显下降,而淋巴细胞百分率增加,均呈极显著差异(P<0.01)。患病大黄鱼总蛋白为(12.8±3.95)g/L,对照组鱼为(19.4±4.33)g/L,病鱼球蛋白、甘油三脂、血糖含量也明显低于对照组(P<0.01)。然而病鱼谷丙转氨酶为(37±5.11)IU/L,对照组为(28±5.54)IU/L;病鱼谷草转氨酶为(164±47.19)IU/L,对照组为(117±21.84)IU/L,均呈极显著差异(P<0.01)。研究结果说明,病鱼肝脏和肾脏组织受损。对患病大黄鱼进行病理组织学观察,结果发现病鱼病变组织头肾、肝出现不同程度的变性以及坏死。细胞超微病变观察发现,头肾肾小管上皮细胞变性、坏死。肝细胞胞浆内脂滴积累多。血清指标的测定可以作为大黄鱼哈维氏弧菌病细菌感染的指标。     

Effect of using Spirulina and Chlorella as feed additives for elevating immunity status of Nile tilapia experimentally infected with Aeromonas hydrophila

The present trial was performed to evaluate the effect of dietary incorporation of dried Spirulina, Chlorella and their mixture on the immune status of Nile tilapia (Oreochromis niloticus) before and after artificial infection with pathogenic bacterium Aeromonas hydrophila (A. hydrophila). Two hundred and forty fish were divided into four groups: (a) a control group fed on a basal diet only, (b) a second group fed on a diet containing Spirulina 15%, (c) a third group fed on a diet containing Chlorella 15%, and (d) a fourth group fed on a diet containing a mixture of both Spirulina 15% and Chlorella 15%. At the end of the experiment (9 weeks), the four groups were experimentally infected with A. hydrophila for 7 days. Antioxidant enzymes, lysozyme and bactericidal activities and histopathological changes were determined just before the challenge test and 7 days post‐challenge. Significant (p ≤ 0.05) increases in fish body protein% before the challenge test and increases in serum antioxidant enzymes, lysozyme and bactericidal activity in the Chlorella and algal mixture groups before and after the challenge test were observed. Spirulina, Chlorella and their mixture groups significantly decreased serum malondialdehyde compared to the control group before and after the challenge test. Using Spirulina, Chlorella and their mixture mitigated the necrotic and degenerative changes induced by A. hydrophila and revealed well‐developed and multiple melanomacrophage centres. Thus, dietary Spirulina, Chlorella and their mixture inclusion in Nile tilapia fish proved to have a protective effect against A. hydrophila infection.     

Pancreas disease (PD) in sea‐reared Atlantic salmon,Salmo salar L., in Norway; a prospective,longitudinal study of disease development and agreement between diagnostic test results

A prospective longitudinal study was performed on three cages at each of three Norwegian Atlantic salmon seawater sites that experienced outbreaks of pancreas disease (PD). Once salmonid alphavirus (SAV) ribonucleic acid (RNA) was detected by real‐time RT‐PCR (Rt RT‐PCR) at a site, it became detected in all studied cages and was persistently found until the end of the study period up to 19 months after first detection. SAV‐specific antibodies were detected at all sites until the end of the study period and were also found at a high prevalence in broodfish at the time of stripping. No evidence of increased viral activity was detected in these broodfish. One site tested negative over several months prior to the first detection of SAV by Rt RT‐PCR and SAV‐specific antibody, which occurred 1 month prior to clinical manifestations of PD. Moribund fish or thin fish/runts that were sampled after the first PD diagnosis had almost twice the risk of testing positive by one or more diagnostic tests compared to that of randomly selected apparently healthy individuals. This paper describes the first detailed investigation of the disease development of PD at site and cage level in Norway, as well as an assessment of the performance and agreement of the commonly used diagnostic tests.