The pathology of Johne''s disease in sheep   总被引：4，自引：0，他引：4  

MJ CARRIGAN  JT SEAMAN 《Australian veterinary journal》1990,67(2):47-50

The clinical, gross and histopathological findings in 50 sheep affected with Johne's disease are described. Clinically 90% were emaciated and 20% showed severe diarrhoea. On necropsy there was thickening of the walls of the intestines, particularly of the ileum, caecum and less frequently the jejunum, but in 36% of sheep the changes were only mild. Histologically there was a granulomatous enteritis, typhlitis and colitis, with the most severe changes in the terminal ileum. High numbers of acid-fast organisms were present in the terminal ileum in over 70% of sheep. Mycobacterium paratuberculosis was cultured from only 8% of the sheep examined.  相似文献   

Haemorrhagic septicaemia in pigs     

JT MACKIE 《Australian veterinary journal》1996,74(5):399-400

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Stability of bacterial leaf spot resistance in peach regenerants under in vitro,greenhouse and field conditions     

F. A. Hammerschlag  D. J. Werner  D. F. Ritchie 《Euphytica》1994,76(1-2):101-106

Summary Phenotypic stability of bacterial leaf spot resistance in peach (Prunus persica (L.) Batsch) regenerants, either selected at the cellular level for insensitivity to a toxic culture filtrate of Xanthomonas campestris pv. pruni or screened at the whole plant level for resistance to X. campestris pv. pruni, was investigated. A detached-leaf bioassay was used to evaluate the original regenerants again after three years in the greenhouse and also after a two to three year cycle of tissue culture propagation. Peach trees derived through micropropagation from the original regenerants were also evaluated after one to three years growth in the field. Although leaf spot resistance was retained in some regenerants over time in the greenhouse, following in vitro propagation, and under field conditions, resistance was either lost or not expressed in others. Regenerants # 19-1 and #156-6, derived from embryo callus of bacterial spot susceptible Sunhigh, were significantly more resistant than Sunhigh. High levels of resistance were exhibited in greenhouse plants and field-grown trees of regenerant #122-1, derived from embryo callus of moderately resistant Redhaven. This research provides additional evidence that selecting or screening for somaclonal variants with disease resistance is a feasible approach to obtaining peach trees with increased levels of bacterial spot resistance.Abbreviations TC Tissue-Cultured - TF Toxic culture Filtrate  相似文献   

Evolution. Feathers, females, and fathers     

Ritchie MG 《Science (New York, N.Y.)》2007,318(5847):54-55

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Self-Assembled Smectic Phases in Rod-Coil Block Copolymers   总被引：1，自引：0，他引：1  

JT Chen  EL Thomas  CK Ober  G Mao 《Science (New York, N.Y.)》1996,273(5273):343-346

Rod-coil block copolymers are self-assembling polymers that combine the physics of orientational ordering of rodlike polymers and the microphase separation of coil-coil block copolymers. Several new solid-state morphologies were observed in a series of anionically synthesized model poly(hexyl isocyanate-b-styrene) rod-coil diblock copolymers examined by transmission electron microscopy and selected-area electron diffraction. The rod-coils formed smectic C-like and O-like morphologies with domain sizes ranging from tens of nanometers to almost 1 micrometer. Both structural and orientational changes were found for increasing rod volume fractions. In addition, some morphologies exhibited spontaneous long-range orientational order over many tens of micrometers.  相似文献   

The quest for stronger, tougher materials     

Ritchie RO 《Science (New York, N.Y.)》2008,320(5875):448; author reply 448

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CCROP—Simulation model for container-grown nursery plant production     

J.B. Million  J.T. Ritchie  T.H. Yeager  C.A. Larsen  C.D. Warner  J.P. Albano 《Scientia Horticulturae》2011

Container Crop Resource Optimization Program (CCROP) is an integrative model which simulates the growth and water and nutrient requirements of a woody ornamental shrub grown in small (2.8–11.4 L) containers in a field environment with overhead sprinkler irrigation. The model was developed for producers, producer advisers and researchers to support best management practice decision-making in container nursery production. We describe the primary processes simulated by CCROP particularly how they differ from traditional crops grown in-ground and assess the ability of CCROP to simulate measured values for a range of irrigation and fertilizer trials and transplanting dates. Results of model testing with 11 trials indicate that CCROP provided reasonable outcomes for biomass and leaf area growth as well as evapotranspiration, runoff (container drainage plus un-intercepted irrigation and rainfall) and nitrogen loss.  相似文献   

Extracutaneous viral inclusions in psittacine beak and feather disease   总被引：1，自引：0，他引：1  

K S Latimer  P M Rakich  I M Kircher  B W Ritchie  F D Niagro  W L Steffens  P D Lukert 《Journal of veterinary diagnostic investigation》1990,2(3):204-207

Thirty-five birds that died with naturally acquired psittacine beak and feather disease (PBFD) were necropsied to identify extracutaneous viral inclusions. Inclusions were found in various tissue sections from 34 of 35 birds. By immunoperoxidase staining, intranuclear and intracytoplasmic inclusion bodies were shown to contain PBFD viral antigen. Inclusion-bearing lesions were widely disseminated but often closely associated with the alimentary tract. Lesions within the palate, esophagus, crop, intestine, bursa of Fabricius, and liver probably serve as sources for viral shedding into the feces.  相似文献   

Congenital hypotrichosis in Poll Dorset sheep     

JT MACKIE  B McINTYRE 《Australian veterinary journal》1992,69(6):146-147

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Production and characterization of monoclonal antibodies to psittacine beak and feather disease virus.     

B W Ritchie  F D Niagro  K S Latimer  W L Steffens  D Pesti  L Aron  P D Lukert 《Journal of veterinary diagnostic investigation》1992,4(1):13-18

Monoclonal antibodies specific for the virus that causes psittacine beak and feather disease (PBFD) were produced by fusing spleen cells from mice immunized with purified concentrated PBFD virus with mouse myeloma cell line Sp2/0. The resulting hybridomas were tested for reactivity against whole purified virus by an enzyme-linked immunosorbent assay (ELISA) system. Four clones, designated 15H8, 8E3, 11G12, and 2C3, were subcloned by limiting dilution. Isotyping indicated that clone 15H8 was secreting IgG, whereas the remaining clones secreted IgM. The secreted immunoglobulins were characterized by reactivity against purified PBFD virus using immunoblotting procedures, by immunohistochemical staining of virus-induced lesions in infected tissues, and by inhibition of PBFD virus agglutination of cockatoo erythrocytes. Antibodies secreted by clones 15H8 and 8E3 had the strongest activity against purified whole virus. Only immunoglobulin secreted by the clone 15H8 could be used to detect viral antigen in infected tissues. None of the monoclonal antibodies had hemagglutination-inhibition activity.  相似文献