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141.
D. S. Johnson T. J. Samuelson 《The Journal of Horticultural Science and Biotechnology》2013,88(5):489-494
Soil managment in a ‘Bramley’s Seedling’ orchard, established in a system of herbicide treated tree rows and mown grass alleys, was changed to provide three treatments: complete grass cover, overall herbicide and a continuation of the existing system. Differential rates of N fertilizer (nil, 62.5 kg ha-1) were applied to each soil management regime. In comparison with herbicide strips, complete grass was intensely competitive, particularly with nil application of N fertilizer, reducing tree growth and yield and greatly decreasing leaf N. Leaves from trees in complete grass (nil N) plots contained higher concentrations of P, K and B but lower ones of Ca, Mn and Cu. Compared with the change from herbicide strip to complete grass management, effects of changing to overall herbicide were smaller. There were slight increases in leaf N concentration but no increases in tree growth or fruit yield. Leaf Mn concentration was increased in overall herbicide. Although application of N fertilizer to grass plots increased leaf N concentration by 0.4% and the three-year girth increment, yield was less than that of trees in herbicide strips. Nitrogen fertilizer applied to herbicide strips or overall herbicide plots slightly increased leaf N content but there was no effect on yield or girth increase. Applying N fertilizer to complete grass plots reduced the concentration of P, K and B in leaves but increased leaf Ca, Mn and Cu. 相似文献
142.
Six lactating Holstein cows were used to determine whether a serum luteinizing hormone (LH) surge induced by luteinizing hormone-releasing hormone (LHRH) could be detected in milk. A double antibody radioimmunoassay was evaluated for measuring LH in whole milk. Cows (d 10 of the estrous cycle) were injected with saline (time zero), followed by LHRH 12 h later. Blood samples were collected hourly for 12 h via jugular cannula following each injection; milk removal was accomplished every 2 h by a portable milking machine. On d 10 of the next estrous cycle, treatment, order was switched, with the same cows receiving LHRH at time zero and saline 12 h later. Approximately 2 h following LHRH treatment, serum LH levels peaked at 29 ng/ml and remained elevated for 5 h. There was no corresponding change in milk LH detected during the 12-h to 24-h period following the induced serum LH surge. Our conclusion is that the measurement of LH in the milk of cows shows little promise for predicting ovulation time in the cow. 相似文献
143.
Johnson L Gough J Spencer Y Hewinson G Vordermeier M Wangoo A 《Veterinary immunology and immunopathology》2006,111(3-4):219-229
Development of necrotic granulomas in response to Mycobacterium bovis infection in cattle is pathognomonic for bovine tuberculosis. Previously our laboratory reported on M. bovis granuloma classification by stage of lesion advancement within bovine lymph nodes and developed immunohistochemical markers to further characterize these granulomas. In this study of bovine lymph node granulomas we applied this classification system to assess the dynamics of vaccination challenge. Lymph nodes collected from cattle vaccinated with M. bovis bacillus Calmette-Guerin (BCG) and subsequently challenged with virulent M. bovis were compared to lymph nodes from unvaccinated, challenged cattle. Expression of interferon-gamma (IFN-gamma), transforming growth factor-beta (TGF-beta), type I procollagen and cell marker identification of T cells, B cells, macrophages and WC1(+)gammadelta TCR+ cells were assessed. Granulomas formed in vaccinated cattle were greatly reduced in number, area, degree of necrosis and peripheral fibrosis and contained fewer Langhans' giant cells, acid fast bacilli, WC1(+)gammadelta TCR+ cells and less TGF-beta expression in comparison to controls. B cells clustered intensely along the outer granuloma margins within vaccinated calves, with significantly more IFN-gamma producing cells identified in the medullary regions of lymph nodes from BCG-vaccinated animals compared to unvaccinated controls. This may be indicative of immune activation and surveillance in regions not directly associated with ongoing disease. Lymph node evaluation using light microscopy and immunohistochemical markers is useful to assess the immune response and discriminate granulomas to determine vaccine efficacy and disease severity. 相似文献
144.
Zuber MT Smith DE Phillips RJ Solomon SC Neumann GA Hauck SA Peale SJ Barnouin OS Head JW Johnson CL Lemoine FG Mazarico E Sun X Torrence MH Freed AM Klimczak C Margot JL Oberst J Perry ME McNutt RL Balcerski JA Michel N Talpe MJ Yang D 《Science (New York, N.Y.)》2012,336(6078):217-220
Laser altimetry by the MESSENGER spacecraft has yielded a topographic model of the northern hemisphere of Mercury. The dynamic range of elevations is considerably smaller than those of Mars or the Moon. The most prominent feature is an extensive lowland at high northern latitudes that hosts the volcanic northern plains. Within this lowland is a broad topographic rise that experienced uplift after plains emplacement. The interior of the 1500-km-diameter Caloris impact basin has been modified so that part of the basin floor now stands higher than the rim. The elevated portion of the floor of Caloris appears to be part of a quasi-linear rise that extends for approximately half the planetary circumference at mid-latitudes. Collectively, these features imply that long-wavelength changes to Mercury's topography occurred after the earliest phases of the planet's geological history. 相似文献
145.
146.
Johnson Stanley Subramanian Chandrasekaran Gnanadhas Preetha Sasthakutty Kuttalam 《Pest management science》2010,66(5):505-510
BACKGROUND: Cardamom, an important spice crop often attacked by many insect pests, is controlled mainly using synthetic insecticides. As honey bees play a vital role in pollination in cardamom, the impact of insecticides on honey bees needs to be explored to assess its safety. RESULTS: Risk assessment based on contact toxicity revealed diafenthiuron to be a non‐selective insecticide to bees with a low selectivity ratio (the ratio between the LD50 for beneficial and pest species). A dose of diafenthiuron that killed 90% of cardamom borer, Conogethes punctiferalis Guenee, was found to kill 100% of Indian bees. Based on the hazard ratio (the ratio between the field‐recommended dose and the LD50 for the beneficial), diafenthiuron was found to be slightly to moderately toxic to bees. Diafenthiuron, even at low concentrations of LC1 (the concentration that killed 1% of bees), was found to affect the foraging and homing behaviour of Indian bees. Of bees fed with 30 µg mL?1 of diafenthiuron, 40% were found missing on the third day after exposure. However, diafenthiuron did not affect bee visits to the cardamom fields. CONCLUSION: Diafenthiuron is more highly toxic to Apis cerana indica F. than to C. punctiferalis by contact, using selectivity ratio and probit substitution methods of risk assessment, but the hazard ratio revealed diafenthiuron to be a slightly to moderately toxic chemical. Diafenthiuron was found to affect the foraging and homing behaviour of bees at sublethal concentrations. Thus, sublethal effects are more relevant in risk assessment than lethal and acute effects. Copyright © 2010 Society of Chemical Industry 相似文献
147.
Dart AJ Little CB Hughes CE Chu O Dowling BA Hodgson DR Rose RJ Johnson KA 《Equine veterinary journal》2003,35(3):302-307
REASONS FOR PERFORMING STUDY: Recombinant equine growth hormone (reGH) has recently been evaluated for effects on body condition and wound healing. It has the potential to influence articular cartilage via stimulation of IGF-1. OBJECTIVES: To investigate effects of administration on synovial joint metabolism. METHODS: Six mature horses were given 20 microg/kg bwt reGH daily for 8 weeks by i.m. injection. Three control horses were injected with sterile water. Serum and synovial fluid samples were collected at 6, 8, 11 and 16 weeks for GH and IGF-1 assays. Articular cartilage harvested at week 16 was evaluated by Western analysis using monoclonal antibodies BC-13, BC-4, 8-A-4 and CH-3. RESULTS: Concentrations of IGF-1 in serum and synovial fluid were significantly elevated (P < 0.05) at 6 and 8 weeks in the reGH group. Glycosaminoglycan concentrations in synovial fluid were significantly less than controls at these time points, suggesting that reGH may modulate proteoglycan metabolism in articular cartilage. In the reGH group, there were not any alterations in synovial fluid content of 3B3(-) epitope or aggrecan metabolite, or in aggrecan or link protein catabolites retained within cartilage, that might be expected with development of osteoarthritis. CONCLUSIONS: Intramuscular administration of reGH may be a more efficient means of delivery of IGF-1 to joints for cartilage resurfacing initiatives. POTENTIAL RELEVANCE: We found no alterations in cartilage metabolism indicative of development of osteoarthritis. 相似文献
148.
149.
OBJECTIVE: To identify factors affecting radial alignment after oblique corrective osteotomy stabilized with a type II external fixator and to evaluate the results of this treatment for antebrachial growth deformities. STUDY DESIGN: Retrospective study SAMPLE POPULATION: Twenty-eight dogs with unilateral antebrachial growth deformities treated with acute corrective osteotomy stabilized with a type II external fixator. METHODS: Medical records and preoperative and postoperative radiographs of the affected and contralateral limb were reviewed. Cause of deformity, age, weight, and gender were recorded. Radial length, varus/valgus angulation, and cranial/caudal angulation were measured from radiographs of the treated and contralateral limbs. Preoperative and postoperative angulation and length discrepancy were compared between affected and contralateral limbs. RESULTS: Correction of varus/valgus angle discrepancy was achieved by using acute corrective osteotomy stabilized with type II external skeletal fixation. No significant change was noted for correction of cranial/caudal angle discrepancy or length discrepancy between the affected and control limb. CLINICAL RELEVANCE: Varus/valgus angle deformities can be treated successfully with type III external fixation after oblique corrective osteotomy. Patients with significant length or cranial/caudal angle discrepancies or both that negatively impact function may require the use of hinged circular fixators or other dynamic techniques to achieve adequate correction. 相似文献
150.
Anderson JD Johnson TV Schubert G Asmar S Jacobson RA Johnston D Lau EL Lewis G Moore WB Taylor A Thomas PC Weinwurm G 《Science (New York, N.Y.)》2005,308(5726):1291-1293
Radio Doppler data from the Galileo spacecraft's encounter with Amalthea, one of Jupiter's small inner moons, on 5 November 2002 yield a mass of (2.08 +/- 0.15) x 10(18) kilograms. Images of Amalthea from two Voyager spacecraft in 1979 and Galileo imaging between November 1996 and June 1997 yield a volume of (2.43 +/- 0.22) x 10(6) cubic kilometers. The satellite thus has a density of 857 +/- 99 kilograms per cubic meter. We suggest that Amalthea is porous and composed of water ice, as well as rocky material, and thus formed in a cold region of the solar system, possibly not at its present location near Jupiter. 相似文献