Pocono mesic till barrens in retreat: topography,fire and forest contagion effects     

Maurice  Keith R.  Welch  Joan M.  Brown  Christopher P.  Latham  Roger Earl 《Landscape Ecology》2004,19(6):603-620

The Pocono mesic till barrens (PMTB) are a unique assemblage of fire-maintained shrub communities that support numerous rare species. Historically these barrens covered a large area in the vicinity of Long Pond, Pennsylvania, USA. However, due largely to regional fire suppression instituted in the early 1960s, over 70% of the area covered by barrens succeeded to fire-intolerant forest that does not support the rare species. We investigated the influence of forest proximity on barrens succession across three geomorphic types during periods of high fire frequency and fire suppression, testing the hypothesis that forest processes such as seed rain, shading, and detrital enrichment of soils enhances barrens succession through a contagion effect. Evidence of a forest contagion effect should be shown by increased rates of barrens succession with increasing proximity to the nearest forest edge. In order to detect a forest contagion effect, barrens persistence and barrens succession were modeled in proximity zones of 0-50 m, 50-100 m, 100-200 m, and greater than 200 m from the nearest forest edge. We used existing GIS data layers for fire, geomorphology, and vegetation distribution in 1938, 1963, and 1992. The layers were modified and overlain using ArcView software to determine persistence and succession rates for each unique combination of layers in each proximity zone from 1938 to 1963 (pre-fire suppression) and 1963 to 1992 (post-fire suppression). ANCOVA results indicate that proximity to the nearest forest edge significantly affected barrens persistence rates in both time periods, but succession rates were significantly affected in 1938 to 1963 only. Twenty-eight percent of the 1938 barrens succeeded to forest by 1963; 56% of the 1963 barrens became forest by 1992. Results support previous findings that barrens persistence is enhanced by increased fire frequency, and that barrens persist longer where they overlie flat glacial till than on other geomorphology types.  相似文献   

Influence of thermal stimulation during the late phase of incubation on hatching results and post-hatch broiler performance under commercial conditions     

A. S. Elmehdawi  M. A. Hall  P. A. Skewes  D. L. Wicker  D. V. Maurice 《British poultry science》2016,57(6):848-854

1. Two experiments, which differed in breeder age, strain and season, were conducted to study the influence of low-intensity, short-duration thermal stimuli during the late phase of incubation on hatchability and performance. The first experiment conducted in April–June used eggs from Cobb × Ross broiler breeders at 35–41 weeks of age and the second experiment performed in February–April used eggs from Hubbard × Cobb broiler breeders at 49–53 weeks of age.

2. Eggs in the test group had the same physical environment as eggs in the control group except that incubation temperature was increased by 1?C for 2 h/d above the control group from 18 to 20 d of incubation (DI).

3. The results demonstrated that thermal stimulation of 1?C for 2 h/d above control incubation temperature during 18–21DI did not have any adverse effects on hatch and post-hatch performance of broilers.

4. In both experiments, treatment did not significantly alter the secondary sex ratio in hatched chickens, but hatch residue showed that the proportion of unhatched male embryos was significantly lower in the test groups than in the control groups.

5. In the first experiment, thermal stimulation improved feed conversion by 1.82% compared with the control.

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Pericardiocentesis and principles of echocardiographic imaging in the patient with cardiac neoplasia     

Gidlewski J  Petrie JP 《Clinical Techniques in Small Animal Practice》2003,18(2):131-134

Ultrasonography is a safe, noninvasive, sensitive, and specific tool for evaluation of the heart and pericardium in patients with cardiac neoplasia. In small animals, the incidence of cardiac neoplasia is low. In dogs, hemangiosarcoma and chemocdectoma are the two most common types of cardiac neoplasia. In cats, lymphosarcoma is the most common form of cardiac neoplasia. Pericardial effusion is a common and potentially life-threatening consequence of cardiac neoplasia. Pericardial effusion leads to a rise in the intrapericardial pressure, resulting in varying degrees of hemodynamic compromise. Cardiac tamponade occurs when the intrapericardial pressure equals or exceeds right ventricular diastolic filling pressures, leading to a decreased cardiac output. Pericardiocentesis is used to stabilize animals with life-threatening cardiac tamponade, and to obtain fluid samples for diagnostic evaluation. The fluid should be quantified and characterized. If the etiology of the effusion is not known, then a sample of the fluid should be submitted for fluid analysis and cytology. Serious complications associated with pericardiocentesis are rare. Complications include cardiac puncture, arrhythmias, and laceration of the tumor or coronary artery, resulting in intrapericardial hemorrhage.  相似文献   

Mastitis and somatic cell counts     

Allen WM  Cheacker C 《The Veterinary record》2003,152(1):28

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Change of porcine circovirus 2 target cells in pigs during development from fetal to early postnatal life   总被引：13，自引：0，他引：13  

Sanchez RE  Meerts P  Nauwynck HJ  Pensaert MB 《Veterinary microbiology》2003,95(1-2):15-25

Change of porcine circovirus 2 (PCV2) target cells during development from fetal to postnatal life in pigs was examined. PCV2 inoculation was performed in fetuses in utero at either 57, 75 or 92 gestational days and in piglets at 1 day of age. Twenty-one days after virus inoculation, PCV2-infected cells in the heart, lungs, liver, spleen and inguinal lymph nodes were localized and immuno-phenotyped by double-immunofluorescence labeling using different cell markers and PCV2-antibodies. During fetal life, viral antigens were detected in cardiomyocytes, hepatocytes and macrophages and infected cell numbers decreased with increasing fetal age at inoculation. The heart contained the highest number of infected cells and cardiomyocytes were the main target cell. Postnatally, macrophages were the only target cell type in different organs and infected cell numbers were similar to those of fetuses inoculated at 92 days of gestation. One piglet showed exceptionally high number of infected cells in different organs with values 13-513-fold higher compared to littermates. In this piglet, the majority of infected cells in lymphoid tissues could not be typed. This study reveals that PCV2 target cells change from cardiomyocytes, hepatocytes and macrophages during fetal life to only macrophages postnatally.  相似文献   

Antibody-induced internalization of viral glycoproteins in pseudorabies virus-infected monocytes and role of the cytoskeleton: a confocal study     

Van de Walle GR  Favoreel HW  Nauwynck HJ  Van Oostveldt P  Pensaert MB 《Veterinary microbiology》2002,86(1-2):51-57

Addition of pseudorabies virus (PrV)-specific polyclonal immunoglobulins to PrV-infected monocytes induces internalization of plasma membrane anchored viral glycoproteins. This process may interfere with antibody-dependent cell lysis and resembles the well-studied physiological endocytosis process. A confocal study was designed to investigate whether the major cellular components, involved in physiological endocytosis (clathrin, actin, dynein and microtubules), play a role in this virological internalization process. In order to visualize the interaction of endosomes, which contain the internalized viral glycoproteins, with clathrin, actin, dynein and microtubules, a double labeling of viral glycoproteins and different cellular proteins was performed. Porcine monocytes were inoculated with the PrV-strain 89V87 at a multiplicity of infection of 50 for 13h. After the addition of FITC-labeled porcine polyclonal PrV-specific antibodies, cells were fixed with para-formaldehyde at different time points and afterwards permeabilized. The different cellular components were visualized with monoclonal antibodies and a Texas Red-conjugate, with the exception of actin, which was stained with phalloidin-Texas Red. The cells were analyzed by confocal microscopy. A clear co-localization was observed between the viral glycoproteins and clathrin and dynein during the internalization process. The microtubules were in close contact with the internalized vesicles. For actin no co-localization could be observed. It can be stated that clathrin, dynein and microtubules, important components during physiological endocytosis, are also of importance during the antibody-induced internalization of viral glycoproteins.  相似文献   

Effectiveness of capillary electrophoresis fluoroimmunoassay of blood PrpSc for evaluation of scrapie pathogenesis in sheep.     

David J Everest  Susan Waterhouse  Tina Kelly  Elena Velo-Rego  Maurice J Sauer 《Journal of veterinary diagnostic investigation》2007,19(5):552-557

Management of prion diseases in livestock would benefit greatly from availability of a validated blood test. A promising immunocapillary electrophoresis technique (also known as capillary electrophoresis fluoroimmunoassay) to detect abnormal prion protein in blood from live sheep is evaluated here. Capillary electrophoresis fluoroimmunoassay was applied to analysis of extracted blood from scrapie-exposed sheep (n = 87; 347 samples) at various stages of incubation, and to control sheep (n = 194; 489 samples). Overall, test values for the control and test populations were not significantly different, and a similar proportion of control (7%) and test (10%) sheep were classified as positive. Over 2-3 month intervals from birth until clinical disease, test specificity and sensitivity ranged from 66.7% to 100% and 0% to 66.7%, respectively, indicating poor diagnostic performance at all stages of pathogenesis. In routine application, in its present form, the capillary electrophoresis fluoroimmunoassay procedure proved to be insufficiently robust for use as a blood test for scrapie diagnosis.  相似文献   

Molecular characterization of the incitant of cowpea bacterial blight and pustule, Xanthomonas campestris pv. vignicola     

Valérie Verdier  Komi Assigbétsé  Gopal Khatri-Chhetri  Kerstin Wydra  Klaus Rudolph  Jean-Paul Geiger 《European journal of plant pathology / European Foundation for Plant Pathology》1998,104(6):595-602

Strains of Xanthomonas campestris pv. vignicola (Xcv), isolated from cowpea leaves with blight or minute pustules and collected from various geographic areas, were selected on the basis of pathological and physiological features. All strains were analyzed for genotypic markers by two methods: ribotyping with EcoRI endonuclease, and RFLP analysis with a plasmid probe (pthB) containing a gene required for pathogenicity from Xanthomonas campestris pv. manihotis. Ribotyping revealed a unique pattern for all the strains that corresponded to the previously described ribotype rRNA7. Based on polymorphism detected by pthB among Xcv strains, nine haplotypes were defined. The observed genetic variation was independent of the geographic origin of the strains and of pathogenic variation. Some haplotypes were widely distributed, whereas others were localized. In some cases, we could differentiate strains isolated from blight symptoms and pustules according to haplotypic composition. However, in most cases, no significant differences were observed. Our results and the previous pathogenic and biochemical characterizations suggest that the strains isolated from leaves with blight symptoms or minute pustules belong to the same pathovar. We provide information on pathogen diversity that can be used to identify and characterize resistant germplasm.  相似文献   

Mediterranean type ecosystems: The role of nutrients: F.J. Kruger,D.T. Mitchell and J.V.M. Jarvis (Editors). Ecological Studies 43, Springer Verlag,Berlin, 1983. 552 pp., DM 98.00, US$ 40.50. ISBN 3-540-12158-7     

Maurice Rapp 《Forest Ecology and Management》1985,11(4):298

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Growth and carcass composition of female turkeys implanted with anabolic agents and fed high-protein and low-protein diets     

D J Castaldo  J E Jones  D V Maurice 《Archives of Animal Nutrition》1990,40(8):703-712

This laboratory investigated the anabolic effect of the synthetic steroid trienbolone acetate (TA) and found it effective in male and female meat turkeys without any apparent gross abnormalities (Poultry Sci., 61: 1386, 1982). The present study was undertaken to characterize the response of female turkeys, fed equicaloric diets varying in dietary protein density to anabolic agents implanted at 13 wks. TA and zeranol (Z) were tested singly and in combination (TAZ). Body weight gain and feed conversion at 16 wks of age were improved (P less than 0.01) with TA and TAZ. The response to TA was enhanced as dietary protein density increased. Carcass fat, protein, ash, energy, potassium, and calcium were not altered by implant treatment. A trend existed toward increased carcass fat with zeranol implantation. Carcass moisture (P less than 0.01) and sodium (P less than 0.05) were increased in the TA treatment. Blood plasma electrolytes were not affected by implant treatments but plasma calcium was decreased (P less than 0.05) by TAZ. No synergism was noted between TA and Z with respect to growth, feed conversion, carcass composition, plasma electrolytes with the exception of plasma calcium. No interaction was observed between dietary protein density and implant treatment. Performance variables increased and carcass fat decreased with increasing dietary protein density. These results confirm our earlier finding with respect to TA and provide additional evidence that dietary protein density influences the response of meat turkeys to TA. The data show that zeranol lacks an anabolic effect in turkeys.  相似文献