Transmission from Seed to Seedling and Secondary Spread of Xanthomonas campestris pv. Campestris in Brassica Transplants: Effects of Dose and Watering Regime     

S.J. Roberts  L.H. Hiltunen  P.J. Hunter  J. Brough 《European journal of plant pathology / European Foundation for Plant Pathology》1999,105(9):879-889

The effects of inoculum load and watering regime on the transmission of Xanthomonas campestris pv. campestris from seed to seedlings of cauliflower were investigated. Seed, inoculated with different concentrations of bacteria, was sown in commercial module trays and subjected to four different watering regimes: high frequency overhead spray, low frequency overhead spray, high frequency capillary and low frequency capillary. Visible symptoms were recorded and leaf washings were carried out to detect the pathogen on symptomless plants. The effects of treatments on symptoms and on the proportion of contaminated but symptomless plants was similar. Initially, they were influenced only by the dose of bacteria with little difference between the watering regimes, but later the proportion of plants with symptoms was greater for plants subjected to overhead watering, due to spread and secondary infection. Generalised linear models were fitted to the data relating the proportion of symptomless contaminated plants or the proportion of plants with symptoms, p, to the mean dose of bacteria per seed, d, and the number of overhead waterings, noh. The equations were: p=1–exp(–0.014·d ^0.32·noh ^0.045) for symptomless contaminated/infected plants and p=1–exp(–0.0056·d ^0.44·noh ^0.014) for plants with symptoms. These models indicated that the one-hit probability for transmission of the pathogen (i.e. with/without visible symptoms) was 0.014 and for infection (i.e. with visible symptoms) was 0.0056.  相似文献   

Experimental reproduction of viral chorioretinitis in kangaroos     

L REDDACLIFF  P KIRKLAND  A PHILBEY  R DAVIS  L VOGELNEST  F HULST  D BLYDE  A DEYKIN  J SMITH  P HOOPER  A GOULD  A HYATT 《Australian veterinary journal》1999,77(8):522-528

OBJECTIVE: To investigate whether preparations containing Wallal and/or Warrego viruses could cause disease when inoculated subcutaneously into captive kangaroos. DESIGN AND PROCEDURE: Four groups of two kangaroos, seronegative to both Wallal and Warrego virus, were each inoculated with wild Wallal virus, cultured Wallal virus, wild Warrego virus, or wild Warrego virus followed by wild Wallal virus after 3 weeks. A single uninoculated animal served as a control. Animals were monitored weekly under anaesthesia, examined ophthalmoscopically (including fundic photography), and samples collected for haematological and serum biochemical analysis, virus isolation, PCR and serological examination for antibodies against Wallal and Warrego viruses. Animals inoculated with cultured Wallal virus were killed at week 10, and remaining kangaroos were reinoculated with cultured Wallal virus at week 12. RESULTS: Virus was isolated from the blood of two kangaroos 2 weeks after inoculation with Wallal virus preparations, and from a third kangaroo 2 weeks after reinoculation. By 3 weeks after inoculation, all kangaroos given Wallal virus preparations had seroconverted to Wallal virus and one had seroconverted to Warrego virus. Fundic changes were detected in the three viraemic kangaroos 4 or more weeks after inoculation, and lesions were present in the eye and brain typical of those seen in field cases of chorioretinitis. No other kangaroos had lesions. Wallal virus was identified by PCR and immunohistochemical analysis in the retina of one affected animal and orbivirus-like particles were seen by electron microscopy in the remains of retinal cells. CONCLUSION: The condition of chorioretinitis was reproduced in three of eight kangaroos by inoculation with preparations containing Wallal virus.  相似文献   

Equine Nasal and Paranasal Sinus Tumours. Part 1: Review of the Literature and Tumour Classification     

K. W. HEAD  P. M. DIXON 《Veterinary journal (London, England : 1997)》1999,157(3):261-278

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中华鳖穿孔病病理变化   总被引：10，自引：0，他引：10  

蔡完其  赵金良 《中国水产科学》1998,5(4):17-22

本文报道由嗜水气单胞菌、普通变形菌等多种细菌引起的中华鳖穿孔病的病理变化。病鳖各脏器发生变质性病变,充血、出血,呈败血症;脏器局部坏死组织中聚有大量脓细胞,呈化脓灶。同健康鳖相比,病鳖１２项血清生化成分有８项发生显著变化：Ｋ＋、Ｃａ２＋、谷草转氨酶和乳酸脱氢酶量增多;Ｎａ＋、Ｃｌ－、胆固醇和碱性磷酸酶量减少;肌肉中酯酶和肝脏中超氧化物歧化酶活性降低。  相似文献   

锯缘青蟹死亡的组织病理学初步观察     

李丹  宋振荣  张志祥 《福建水产》2009,(3):7-10

对2008年8月福建省泉州市某海水场养殖锯缘青蟹中发生的死亡现象,开展锯缘青蟹的组织病理学研究。解剖可见肌肉明显坏死、溶解;头胸甲储积大量暗黄色体液,经福尔马林固定成固态物质;光镜下发现病蟹的中肠腺上皮细胞坏死、细胞质中出现大型的包涵体;电镜下发现病蟹的细胞质中有长约为500hm、宽约为200hm杆状结构的疑似杆状病毒存在。  相似文献   

Outbreaks of viral nervous necrosis in juvenile and adult farmed Atlantic cod, Gadus morhua L., in Norway     

H Hellberg  A Kvellestad  B Dannevig  G Bornø  I Modahl  R N Haldorsen  F Vik-Mo  K Ottesen  E M Sætre  H Sindre 《Journal of fish diseases》2010,33(1):75-81

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Liver involvement in post‐smolt Atlantic salmon,Salmo salar L., infected with infectious pancreatic necrosis virus (IPNV): a retrospective histopathological study     

P A Noguera  D W Bruno 《Journal of fish diseases》2010,33(10):819-832

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Methacarn preserves mucus integrity and improves visualization of amoebae in gills of Atlantic salmon (Salmo salar L.)     

Carolina Fernandez  Dario Mascolo  Sean J. Monaghan  Johanna L. Baily  Lynn Chalmers  Giuseppe Paladini  Alexandra Adams  James E. Bron  Sophie Fridman 《Journal of fish diseases》2019,42(6):883-894

Two aqueous fixation methods (modified Davidson's solution and modified Davidson's solution with 2% (w/v) Alcian blue) were compared against two non‐aqueous fixation methods (methacarn solution and methacarn solution with 2% (w/v) Alcian blue) along with the standard buffered formalin fixation method to (a) improve preservation of the mucous coat on Atlantic salmon, Salmo salar L., gills and (b) to examine the interaction between the amoebae and mucus on the gill during an infection with amoebic gill disease. Aqueous fixatives demonstrated excellent cytological preservation but failed to deliver the preservation of the mucus when compared to the non‐aqueous‐based fixatives; qualitative and semi‐quantitative analysis revealed a greater preservation of the gill mucus using the non‐aqueous methacarn solution. A combination of this fixation method and an Alcian blue/Periodic acid–Schiff staining was tested in gills of Atlantic salmon infected with amoebic gill disease; lectin labelling was also used to confirm the mucus preservation in the methacarn‐fixed tissue. Amoebae were observed closely associated with the mucus demonstrating that the techniques employed for preservation of the mucous coat can indeed avoid the loss of potential mucus‐embedded parasites, thus providing a better understanding of the relationship between the mucus and parasite.  相似文献   

《动物病理》课程思政课堂教学案例     

李桂珍  黄爱芳  张欣  张媚玉  丁雪瑶  王少杰 《畜牧兽医杂志》2024,43(1):68-70

《动物病理》作为一门重要的专业基础课在畜牧兽医专业开出,在对学生的专业知识和技能进行培养的同时,融入思政元素,培养学生“懂农业,爱农村,爱农民”的从农素养,更好地为国家乡村振兴发展培养专业人才。本文从课程教学案例出发探究课程思政的实施方法与初步成效。  相似文献   

MAPKs and acetyl-CoA are associated with Curvularia lunata pathogenicity and toxin production in maize     

Xuan NI  Jin-xin GAO  Chuan-jin YU  Meng WANG  Jia-nan SUN  Ya-qian LI  Jie CHEN 《农业科学学报》2018,17(1):139-148

Mitogen-activated protein kinase (MAPK) cascades play an important role in extracellular signal transduction and are involved in the pathogenicity of fungal pathogens to host plants. In Curvularia lunata, the roles of two MAPK genes, Clk1 and Clm1, have already been studied. Clk1 is involved in conidia formation and pathogenicity, and Clm1 is closely related to pathogen cell wall formation and pathogenicity to maize leaves. In this study, a third C. lunata MAPK gene, Clh1, which is homologous to hog1, was successfully cloned. We found that a Clh1 deletion mutant had lower intracellular glycerol accumulation than the wild-type stain and was unable to grow normally under osmotic stress conditions. Furthermore, the deletion mutants of three C. lunata MAPK genes (Clk1, Clm1 and Clh1) had lower levels of acetyl-CoA, which is an important intermediate product in the synthesis of melanin and furan toxin, and down-regulated expression of pathogenicity-associated genes. Furthermore, pathogenicity and the ability to produce toxin were restored after adding acetyl-CoA to the culture medium, suggesting that acetyl-CoA is closely involved in the pathogen MAPK signaling pathway.  相似文献