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101.
Georg Jentschke Eberhard Fritz Petra Marschner Christine Rapp Volkmar Wolters Douglas L. Godbold 《植物养料与土壤学杂志》1997,160(2):317-321
Non-inoculated spruce seedlings (Picea abies Karst.) and spruce seedlings colonized with Lactarius rufus Fr., Pisolithus tinctorius Coker & Couch or Paxillus involutus Fr. were grown for 35 or 37 weeks in a microcosm system on two types of natural forest humus differing in Pb content. Using X-ray microanalysis, the distribution and content of Pb in the tissues of mycorrhizal and non-mycorrhizal root tips were compared. No significant difference in the Pb contents of root cortex cell walls of non-mycorrhizal and seedlings colonized by Lactarius rufus, Pisolithus tinctorius, or indigenous mycorrhizal fungi (mainly Tylospora sp.) was found. However, in root tips of seedlings colonized by Paxillus involutus, due to a higher binding capacity for cations, the Pb content in cell walls of the root cortex were higher than in non-mycorrhizal roots. Pb contents in cell walls of the cortex of mycorrhizal and non-mycorrhizal roots were 3 times higher in plants growing in humus with a high Pb content than in plants growing in humus with a low Pb content. It is concluded that increasing contents of Pb in the organic matter may lead to an increased loading of the apoplast with Pb. The mycobionts tested in this investigation did not exclude Pb from root tissues. 相似文献
102.
Maria Durban Christine A. Hackett James W. McNicol Adrian C. Newton William T. B. Thomas Iain D. Currie 《Journal of Agricultural, Biological & Environmental Statistics》2003,8(1):48-66
This article examines the practical use of semiparametric models in the analysis of field trials—that is, models with parameterized treatment effects and additive terms derived by a data-driven approach using a locally weighted running line smoother (loess). We discuss graphical methods to identify spatial structure in the data and model selection procedures to choose the degree of smoothing. Once the spatial part of the model has been chosen, hypotheses about the treatment effects may be tested. Semiparametric models are used to analyze two barley field trials exhibiting spatial trends. The first has a single experimental treatment and a row-column design. The second has a split-plot design, and we use a semiparametric model which accounts for the randomization at the different strata of this design. We compare the semiparametric analyses with classical analyses of variance and with alternative spatial models. We find that semiparametric models give a good insight into spatial variation in the field and can improve the precision of parameter estimates. 相似文献
103.
Christine Alewell 《Water, air, and soil pollution》2001,130(1-4):1271-1276
Because of the deleterious effects of acid rain and the need to predict reversibility of acidification, various scientific tools such as modeling, stable isotopes and flux/budget calculations have been used in biogeochemical sulfur (S) research. The aim of this study was to evaluate consistencies and discrepancies between these different tools. While modeling has been seemingly successful in predicting S dynamics in soil solution and stream water by considering inorganic sulfate sorption and desorption only, stable S isotopes indicate that biological S turnover plays a crucial role for the sulfate released to soil solution and stream water. A comparison of budget calculations with soil S pools reveals that inorganic sulfate sorption and desorption are the controlling processes as long as deposition is high (> 15 kg S ha?1yr?1) and soils have a high sulfate sorption capacity. This explains the successful model predictions of the last two decades. However, for soils with low sulfate sorption capacity and under low sulfate deposition, organic S seems to be a significant source for stream water sulfate and has to be considered in future modeling. 相似文献
104.
105.
The interactive effects of UV-B and insecticide exposure on tadpole survival, growth and development
Because declines within amphibian populations can seldom be attributed to a single cause, it is important to focus on multiple stressors, both natural and anthropogenic. Variables such as UV-B radiation and chemical contamination can interact with one another in ways that might not be predicted from single-factor studies. We exposed southern leopard frog (Rana sphenocephala) tadpoles to the insecticide carbaryl and varying intensities of UV-B radiation in artificial ponds and examined their effects on survival, size at metamorphosis, and the duration of the larval period. Tadpole survival to metamorphosis was positively influenced by UV-B intensity. Tadpoles in ponds exposed to carbaryl contained over three times more algae and yielded larger metamorphs than control ponds. Although previous laboratory studies have indicated carbaryl becomes more toxic in the presence of UV-B, we did not find such an effect, perhaps because of the protection afforded by dissolved organic carbon within the ponds. Our research emphasizes the importance of conducting field studies to more accurately predict what occurs under a natural setting. 相似文献
106.
G. J. Baker R. G. Breeze Christine O. Dawson 《The Journal of small animal practice》1972,13(11):649-653
An oral lesion in a cat caused by the actinomycete Dermatophilus con-golensis is described. Multiple granulomata were present in biopsy material taken from a tongue lesion. After surgical excision and daily penicillin therapy the condition regressed.
Résumé. Une lésion oralle dans un chat, causée par l'actinomycète Dermatophilus congolensis est décrit. Des granulomes multiples étaient présentes dans la substance de la biopsie, prise de la lésion de la langue. Après l'excision chirurgicale et la thérapie journalière de pénicilline, la condition décroissait.
Zusammenfassung. Man beschreibt eine orale Verletzung in einer Katze, die durch den Strahlenpilz Dermatophilus congolensis , verursachet wird. Die multipelen Granulomata waren im Stoff von der Biopsie, Welches von der Verletzung der Zunge, genommen wird. Der Zustand klang ab, nach der chirurgischen Exicision und nach der täglichen Heilung von Penizillin. 相似文献
Résumé. Une lésion oralle dans un chat, causée par l'actinomycète Dermatophilus congolensis est décrit. Des granulomes multiples étaient présentes dans la substance de la biopsie, prise de la lésion de la langue. Après l'excision chirurgicale et la thérapie journalière de pénicilline, la condition décroissait.
Zusammenfassung. Man beschreibt eine orale Verletzung in einer Katze, die durch den Strahlenpilz Dermatophilus congolensis , verursachet wird. Die multipelen Granulomata waren im Stoff von der Biopsie, Welches von der Verletzung der Zunge, genommen wird. Der Zustand klang ab, nach der chirurgischen Exicision und nach der täglichen Heilung von Penizillin. 相似文献
107.
Phorate residues in peat blocks and lettuce were determined following incorporation of the insecticide into different block and ‘Speedling’ cell sizes. Between-block variability was influenced little by block size. Phorate oxidation was most extensive in the largest blocks containing the smallest dose. Total residue concentrations in the lettuce declined from the time of planting to harvest, although accumulation of insecticide continued and was related more to dose than to block or cell size. Residues in the lettuce at harvest exceeded the proposed maximum limit of 0.2 mg kg?1 in some treatments. Residues at planting comprised mainly the parent sulphoxide and sulphone, but by harvest, the oxygen analogue sulphoxide and sulphone predominated. Lettuce weight was not influenced by dose but was related directly to block size. Carbofuran and chlorfenvinphos residues were determined in calabrese sown into two sizes of blocks. At planting time, carbofuran residue concentrations were 100 times greater than those of chlorfenvinphos but residues of both insecticides in the mature heads were < 0.01 mg kg?1. Seedling weights in both sowings declined with increasing concentrations of the insecticides. It was concluded that manipulations of block size and the dose of insecticide need to be evaluated for individual insecticide/crop combinations to exploit the technique fully. 相似文献
108.
Following experimental and commercial applications to soil of a granular formulalation of phorate (O,O-diethyl S-ethylthiomethyl phosphorodithioate), residues in the soil and in lettuce were determined by gas-liquid chromatography. When applied by the bow-wave method as a continuous logarithmically-changing dose ranging from approximately 0.9 to 16.0 kg a.i. ha?1, the proportional rate of oxidation in soil of phorate sulphoxide to phorate sulphone was inversely related to dose. Ten weeks after application, total phorate residues in the soil had declined by about 35% at all dose levels. Residues in mature lettuce, from the 1-5 kg ha?1 dose-range, comprised the parent and oxygen analogue sulphoxides and sulphones; the relative proportions of the individual metabolites were independent of dose. Over this dose-range, total residue concentrations in the crop became proportionally slightly greater with increasing dose. When single doses of 1.1, 2.0 or 2.2 kg a.i. ha?1 were applied at drilling, the total residue concentrations in the lettuce declined from 5 mg kg?1 in seedlings from some treatments to <0.05 mg kg?1 at harvest. In plants raised in peat blocks containing 10 or 20 mg a.i. per block, however, residues in seedlings totalled 45-47 mg kg?1 and declined to only 0.7 mg kg?1 at harvest. It was concluded that bowwave applications of phorate when field-sowing lettuce were unlikely to lead to unacceptable residues in the harvested crop, but that residues in lettuce raised in phorate-treated peat blocks may be unacceptably high. 相似文献
109.
The case histories of thirty-five dogs with cervical spondylopathy are described with particular emphasis on diagnosis and surgical treatment, with follow-up records of both treated and untreated cases. Some evidence is presented to show that the syndrome is an inherited defect. 相似文献
110.
Stephanie C. Essman DVM John P. Hoover MS DVM Robert J. Bahr DVM Jerry W. Ritchey DVM PhD Christine Watson DVM 《Veterinary radiology & ultrasound》2002,43(3):255-259
A 7-year-old, neutered male Labrador Retriever presented for a persistent, productive cough and regurgitation. Radiography, ultrasonography, and computed tomography confirmed a large, smoothly marginated intrathoracic mass causing tracheal compression. The mass was removed via a thoracotomy, and a malignant peripheral nerve sheath tumor, most likely originating from the ventral spinal nerve roots, was confirmed using immunohistochemistry. 相似文献