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991.
ABSTRACT Fusarium oxysporum f. sp. canariensis causes Fusarium wilt disease on the Canary Island date palm (Phoenix canariensis). To facilitate disease management, a polymerase chain reaction diagnostic method has been developed to rapidly detect the pathogen. A partial genomic library of F. oxysporum f. sp. canariensis isolate 95-913 was used to identify a DNA sequence diagnostic for a lineage containing all tested isolates of F. oxysporum f. sp. canariensis. Two oligonucleotide primers were designed and used to amplify a 567-bp fragment with F. oxysporum f. sp. canariensis DNAs. DNA from 61 outgroup isolates did not amplify using these primers. Once the primers were shown to amplify a 0.567-kb fragment from DNA of all the F. oxysporum f. sp. canariensis isolates tested, a rapid DNA extraction procedure was developed that led to the correct identification of 98% of the tested F. oxysporum f. sp. canariensis isolates. 相似文献
992.
ABSTRACT In excised dormant stems of peach (Prunus persica), prune (Prunus domestica), and almond (Prunus dulcis), stem diameter, stem hydration, and freezing-thawing influenced the extent of infection caused by Pseudomonas syringae pv. syringae. Bacterial lesion length increased with increasing stem diameter, demonstrating the need to account for the effects of stem diameter when lesion length data are analyzed. Lesion length increased or decreased with stem hydration or dehydration, respectively. However, tissue water content was not a good indicator of tissue susceptibility to infection by P. syringae pv. syringae, as larger diameter stems had larger lesions and lower water content than did smaller diameter stems. After freezing at -5 degrees C for 12 to 24 h, inoculations made during the thawing process produced significantly larger lesions than did inoculations performed before freezing or after thawing. These results support the hypothesis that the increased susceptibility to bacterial canker that is associated with noninjurious freezing is a result of the increased passive spread of bacteria through water redistribution when inoculation is performed during the thawing process. Plant tissue water relationship characteristics that can influence water movement during freezing and thawing may be an important component of bacterial canker development in stone fruit trees. 相似文献
993.
ABSTRACT A generalized two-dimensional Gaussian model is proposed to describe disease foci of head blight of wheat in plots (100 to 2,500 m(2)) originating from small areas (1 to 16 m(2)) inoculated with Gibberella zeae-colonized corn kernels. These anisotropic, asymmetrical foci arose from ascospores produced in perithecia. The model is Z = exp[-(AX(2) + BY(2) + CXY + DX + EY + F)], in which Z = the incidence of seed or spikelet infection at point (X,Y) located in the plot, exp = the exponential function, X = the abscissa or spatial coordinate of the point along a given axis (approximately parallel to the average wind vector during the period of spore release in these experiments), Y = the ordinate or spatial coordinate of the point along the axis perpendicular to the X axis (approximately perpendicular to the wind direction in these experiments), A and B = the quadratic coefficients of the second-order polynomial AX(2) + BY(2) + CXY + DX + EY + F, C = the bilinear coefficient, D and E = the linear coefficients, and exp(-F) = the incidence of seed or spikelet infection at the focus peak in which X = 0 and Y = 0. The generalized two-dimensional Gaussian model was tested on data from a circular or isotropic focus, an elliptical or anisotropic focus with two axes of symmetry, and two anisotropic foci with one and zero axis of symmetry. Its goodness-of-fit (r(2) and adjusted r(2)) was compared with the inverse power, modified inverse power, exponential, and classical Gaussian models. Submodels using only the linear terms, only the quadratic terms, or combinations selected from stepwise regression procedures using various probabilities to enter and to stay and a procedure maximizing the adjusted r (2) were also considered. Spatial analysis of the residuals was performed using Geary's c coefficient at the first distance class. For the circular and elliptical foci, our model provided a fit similar to the modified inverse power and exponential models. However, for anisotropic foci with one or zero axis of symmetry arising from ascospores influenced by wind direction, the generalized two-dimensional Gaussian model provided a better fit. For these anisotropic foci, the linear term X but not the quadratic term X(2) was generally retained in the model, indicating an exponential gradient in the direction parallel to the wind. In all models, the quadratic term Y(2) was retained, along with Y in some cases, indicating that the gradient in the direction roughly perpendicular to the wind was Gaussian or Gaussian-exponential in shape. The bilinear term XY provided an indication of the orientation of the focus in relation to the axes of the sampling grid. This model has the versatility and parameters (quadratic, bilinear, and linear) to better describe the anisotropy of foci from wind-dispersed spores. 相似文献
994.
Herbst LH Jacobson ER Klein PA Balazs GH Moretti R Brown T Sundberg JP 《Veterinary pathology》1999,36(6):551-564
Tumor biopsy samples from 25 Floridian and 15 Hawaiian green turtles (Chelonia mydas) with spontaneous green turtle fibropapillomatosis (GTFP) and from 27 captive-reared green turtles with experimentally induced GTFP were examined microscopically to differentiate the histologic features that result from GTFP pathogenesis and those that result from incidental factors that may vary according to geographic region. Common histologic features for spontaneous and experimentally induced tumors included fibroblast proliferation in the superficial dermis, epidermal acanthosis and hyperkeratosis, epidermal basal cell degeneration with dermal-epidermal cleft formation, spinous layer degeneration with intraepidermal vesicle and pustule formation, and ulceration. Visceral tumors, found in eight of 10 (80%) free-ranging turtles with cutaneous disease that were examined after death, had extensive interstitial fibrous proliferation. The presence of spirorchid trematode eggs and associated foreign body granulomas, common secondary findings within spontaneous tumors, varied by geographic location, and these findings were not observed in experimentally induced tumors. Eosinophilic intranuclear inclusions and intranuclear herpesvirus-associated antigen immunoreactivity were found in 18 of 38 (47%) experimentally induced cutaneous tumors and nine of 119 (7.5%) spontaneous tumors from Floridian but not Hawaiian turtles. The possible involvement of GTFP-associated herpesvirus in the pathogenesis of epidermal degenerative changes and GTFP pathogenesis is discussed. 相似文献
995.
Dystrophic epidermolysis bullosa was diagnosed in a cat with juvenile-onset epithelial sloughing of the oral mucosa, footpads, and haired skin. Dermoepidermal separation occurred in the absence of inflammation or cytolysis of basal epidermal cells. Collagen IV-specific immunostaining corroborated the fact that clefting took place below the epidermal basement membrane. Ultrastructural examination revealed that the proband's anchoring fibrils exhibited a filamentous morphology and were decreased in number compared with those in a normal cat. Finally, the attenuated immunoreactivity for collagen VII in our patient led us to suspect that its encoding gene, COL7A1, could be mutated in this case of feline dystrophic epidermolysis bullosa. 相似文献
996.
Liver pathology and immune response in experimental Fasciola hepatica infections of goats 总被引:1,自引:0,他引:1
Martínez-Moreno A Jiménez-Luque V Moreno T Redondo ES de las Mulas JM Pérez J 《Veterinary parasitology》1999,82(1):19-33
The relationship between the immune response and the pathogenesis of the disease was studied in different primary and secondary experimental Fasciola hepatica infections of goats. The establishment of the infection, measured as percentage of recovered flukes at the necropsy, was similar in primarily and secondarily infected animals (between 19.7% and 24.3%), but the hepatic damage was much more severe in secondarily infected goats, as revealed by the levels of serum hepatic enzymes GGT and LDH. Primary infection evolves to chronic fasciolosis that did not induce the development of resistance, since goats were highly susceptible to secondary infection, showing severe acute and chronic hepatic lesions that led to the death of some animals in each group. The immune response to the infection was proved by the production of specific IgG antibodies to ESP of F. hepatica and the involvement of CD3+ T lymphocytes and lambda IgG+ plasma cells in the hepatic infiltrate. Secondary infection did not induce any difference in either IgG response or in the cellular composition of the infiltrate of hepatic lesions, although this was much more extended. However, neither antibodies nor cell-mediated response were protective: there was no correlation between IgG levels and fluke burden and there was no evidence of cell-mediated killing of the parasite. This suggests the existence of some immune evasion mechanisms in goat infection with F. hepatica. The parasite may depress the local inflammatory and immune response, as suggested by the scarcity of CD3+ T cells in the infiltrate surrounding acute migratory tunnels. Moreover, in secondary infected goats can be suspected an immunological damage of the liver, since a very severe infiltrate of immune cells replaced wide areas of hepatic parenchyma and an immune-mediated damage of hepatocytes could occur. 相似文献
997.
Tsuji N Ohta M Kawazu S Kamio T Isobe T Shimura K Fujisaki K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(12):1331-1333
DNA polymorphism in twelve starains of Eimeria tenella isolated from various places in Japan was examined using 1.l kb small subunits ribosomal RNA amplified by PCR. Genetic variation was evaluated by random amplification of polymorphic DNA (RAPD) analysis. DNA fingerprint patterns were grouped into two, indicating that at least two DNA polymorphisms exist in Japanese E. tenella strains. 相似文献
998.
Tsujimura K Mizutani T Kariwa H Yoshimatsu K Ogino M Morii Y Inagaki H Arikawa J Takashima I 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(2):113-117
For a serological diagnostic test for Borna disease (BD), we developed a capture ELISA with specificity and sensitivity based on detection of antibodies against BD virus (BDV) p40 protein. Using our capture ELISA system, the antibody response of rats inoculated intracerebrally with BDV at 4 weeks after birth showed a sharp increase from 1 to 4 weeks postinoculation (p.i.) and a steady level after 5 weeks p.i. To investigate prevalence of BDV infection among wild rats, we examined sera of Rattus norvegicus in Kami-iso town, Oshima district, Hokkaido, suggesting that rats in this area had not been infected by BDV. 相似文献
999.
Effects of maternal acetazolamide treatment on body weights and incisor development of the fetal rat
Kojima N Naya M Makita T 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(2):143-147
The incisor development of fetal rats on gestation day 19 was well correlated with their fetal weights. The number of odontoblasts in the mandibular incisors, an index of incisor development, increased more than that of the maxillary incisors with increase in fetal body weights. Maternal acetazolamide treatments were observed to suppress the mean fetal weight and to retard incisor development. A smaller incisor size, a thinner predentin layer, and fewer odontoblasts were characteristic of the acetazolamide group. There was also a good correlation between the fetal weights and the number of odontoblasts in the acetazolamide group. From these results, we postulated that the retarded incisor development of the fetal rats caused by the maternal acetazolamide treatment was related to their suppressed fetal weights. However, the regression coefficient of the fetal weights and the number of odontoblasts in the acetazolamide group was smaller than that of the vehicle control group. It may indicate that retarded incisor development in response to maternal acetazolamide treatment is to some extent independent of suppressed fetal weight. 相似文献
1000.
Kawakami E Arai T Oishi I 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》1999,61(2):183-184
Hyaluronidase, acrosin and N-acetylhexosaminidase activities were examined in sperm collected from 12 beagle dogs and in culture medium after 0.5 hr and 7 hr of sperm incubation. The activities of the three enzymes were significantly higher at 7 hr than at 0.5 hr (P < 0.05, 0.01), and the increases were associated with sperm capacitation. It was considered that the three enzymes in the dog sperm are related to fertilization by reason of the findings of the release of these enzymes from the sperm into the medium after 7 hr of incubation. 相似文献