Idiopathic granulomatous disease involving the skin in a horse     

S E Heath  R J Bell  E G Clark  D M Haines 《Journal of the American Veterinary Medical Association》1990,197(8):1033-1036

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The role of p38 mitogen-activated kinase (MAPK) in the mechanism regulating cyclooxygenase gene expression in equine leukocytes     

Eckert RE  Neuder LE  Bell JL  Trujillo JC  Jones SL 《Veterinary immunology and immunopathology》2007,118(3-4):294-303

The goal of this study was to define the role for p38 mitogen-activated kinase (MAPK) in the signaling mechanism regulating pro-inflammatory cyclooxygenase (COX) gene expression in lipopolysaccharide (LPS)-activated equine leukocytes for the purposes of identifying novel targets for anti-inflammatory therapy in endotoxemic horses. The p38 MAPK has been shown to positively regulate inflammatory gene expression in human leukocytes and can be activated by a variety of stimuli including LPS, TNF-alpha, and IL-1. Activation-associated phosphorylated p38 MAPK has been implicated in the up-regulation of several inflammatory genes, including COX-2 which ultimately results in the production of prostanoids that are responsible for the pathophysiology associated with endotoxemia. Our hypothesis is that activation of p38 MAPK is essential for LPS-induced COX-2 expression in equine peripheral blood leukocytes. We tested our hypothesis by investigating the effects of the specific p38 MAPK inhibitors SB203580 and SB202190 on LPS-induced COX-2 protein expression and PGE(2) production in equine leukocytes. LPS stimulation activated p38 MAPK and increased COX-2 expression in a dose-dependent manner with maximal activation observed after 30min and 4h, respectively, at a concentration of 10 ng/ml LPS. In contrast, LPS stimulation did not affect COX-1 protein expression. Pretreatment with SB203580 or SB202190 significantly inhibited LPS-induced activation-associated p38 MAPK phosphorylation, COX-2 mRNA and protein levels, and PGE(2) production in equine leukocytes. Maximal inhibition of LPS-induced COX-2 protein expression was achieved at a concentration of 10 microM SB203580. We concluded that p38 MAPK is essential for LPS-induced COX-2 expression suggesting that p38 MAPK is a potential target for anti-inflammatory therapy during equine endotoxemia.  相似文献   

The use of isoenzyme polymorphisms as an aid for cultivar identification in strawberry     

J. A. Bell  D. W. Simpson 《Euphytica》1994,77(1-2):113-117

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水分状况及硼素营养对油菜苗期根系生长及硼营养效率的影响   总被引：7，自引：1，他引：7  

娄运生  杨玉爱  张桃林  徐建民  R.W.Bell 《植物营养与肥料学报》2001,7(1):71-77

采用温室盆栽试验 ,研究了不同土壤水分条件下施硼对油菜苗期根系生长、硼吸收、利用及其移动性的影响。结果表明 ,随土壤含水量、施硼量的下降 ,油菜根长、根体积、根系生长速率、根 /冠比减小 ,根系及地上部干物质积累降低 ,植株地上部硼浓度及含硼量下降。而硼利用效率、硼运移指数则随土壤含水量、施硼量的下降而升高。不同油菜品种的根系形态参数 (包括根长、根体积、根干重、根冠比及根系生长速率 )、硼利用效率及运移指数存在明显差异 ,即在相同条件下 ,V1根系较发达 ,硼利用效率、运移指数均高于V4 。研究认为 ,根系发达程度、硼利用效率及硼移动性大小是不同基因型油菜耐缺硼差异的重要因素。  相似文献   

Soil sorption–desorption of phosphorus from piggery effluent compared with inorganic sources     

M. R. Redding  T. Shatte  & K. Bell 《European Journal of Soil Science》2006,57(2):134-146

The leaching of phosphorus (P) within soils can be a limiting consideration for the sustainable operation of intensive livestock enterprises. Sorption curves are widely used to assist estimation of P retention, though the effect of effluent constituents on their accuracy is not well understood. We conducted a series of P‐sorption–desorption batch experiments with an Oxic Haplustalf (soil 1), Haplusterts (soils 2 and 3), and a Natrustalf (soil 4). Phosphorus sources included effluent, orthophosphate‐P in a matrix replicating the effluent's salt constituents (the reference solution), and an orthophosphate‐P solution. Treated soils were incubated for up to 193 days before sequential desorption extraction. Effluent constituents, probably the organic or particulate components, temporarily increased the vulnerability of sorbed‐P to desorption. The increase in vulnerability was removed by 2–113 days of incubation (25°C). Despite vigorous extraction for 20 consecutive days, some P sorbed as part of the treatments of soils 1 and 2 was not desorbed. The increased vulnerability due to effluent constituents lasted a maximum of about one cropping season and, for all other treatments, adsorption curves overestimated vulnerability to desorption. Therefore, adsorption curves provide a conservative estimate of vulnerability to desorption where effluent is used in continued crop production in these soils.  相似文献   

Ecological correlates of paternal investment of urates in a tropical cockroach     

Schal C  Bell WJ 《Science (New York, N.Y.)》1982,218(4568):170-173

Females of the tropical cockroach Xestoblatta hamata feed on urates offered by the male after copulation. Females on nitrogen-deficient diets ingest and transfer to their maturing oocytes more male-derived uric acid than do females on high-protein diets. In isolated females, the greatest uptake of uric acid by the ovaries occurs during the mating stage in the reproductive cycle. Uric acid from males contributes significantly to the female's nitrogen pool and may help shorten the time between mating and oviposition. In both field and laboratory experiments males choose high-protein foods and dietary uric acid.  相似文献   

Early Man Site Found in Highland Ecuador     

Mayer-Oakes WJ  Bell RE 《Science (New York, N.Y.)》1960,131(3416):1805-1806

Field investigations in Ecuador have produced archeological evidence for the occupation of the northern Andes by early nomadic hunters. Surface collections and test excavations have demonstrated a complex of stone tools with typological relationships to level I at Fell's Cave in southern Chile, and technological relationships to the late Pleistocene "fluted point" complexes of North America. The date of these materials is estimated at 7000 to 8000 B.C.  相似文献   

Water in Earth's Mantle: The Role of Nominally Anhydrous Minerals   总被引：8，自引：0，他引：8  

Bell DR  Rossman GR 《Science (New York, N.Y.)》1992,255(5050):1391-1397

Most minerals of Earth's upper mantle contain small amounts of hydrogen, structurally bound as hydroxyl (OH). The OH concentration in each mineral species is variable, in some cases reflecting the geological environment of mineral formation. Of the major mantle minerals, pyroxenes are the most hydrous, typically containing approximately 200 to 500 parts per million H(2)O by weight, and probably dominate the water budget and hydrogen geochemistry of mantle rocks that do not contain a hydrous phase. Garnets and olivines commonly contain approximately 1 to 50 parts per million. Nominally anhydrous minerals constitute a significant reservoir for mantle hydrogen, possibly accommodating all water in the depleted mantle and providing a possible mechanism to recycle water from Earth's surface into the deep mantle.  相似文献   

Conservation of brain amyloid proteins in aged mammals and humans with Alzheimer's disease   总被引：37，自引：0，他引：37  

D J Selkoe  D S Bell  M B Podlisny  D L Price  L C Cork 《Science (New York, N.Y.)》1987,235(4791):873-877

The formation of clusters of altered axons and dendrites surrounding extracellular deposits of amyloid filaments (neuritic plaques) is a major feature of the human brain in both aging and Alzheimer's disease. A panel of antibodies against amyloid filaments and their constituent proteins from humans with Alzheimer's disease cross-reacted with neuritic plaque and cerebrovascular amyloid deposits in five other species of aged mammals, including monkey, orangutan, polar bear, and dog. Antibodies to a 28-amino acid peptide representing the partial protein sequence of the human amyloid filaments recognized the cortical and microvascular amyloid of all of the aged mammals examined. Plaque amyloid, plaque neurites, and neuronal cell bodies in the aged animals showed no reaction with antibodies to human paired helical filaments. Thus, with age, the amyloid proteins associated with progressive cortical degeneration in Alzheimer's disease are also deposited in the brains of other mammals. Aged primates can provide biochemically relevant models for principal features of Alzheimer's disease: cerebrovascular amyloidosis and neuritic plaque formation.  相似文献   

Replacements of Pro86 in phage T4 lysozyme extend an alpha-helix but do not alter protein stability   总被引：10，自引：0，他引：10  

T Alber  J A Bell  D P Sun  H Nicholson  J A Wozniak  S Cook  B W Matthews 《Science (New York, N.Y.)》1988,239(4840):631-635

To investigate the relation between protein stability and the predicted stabilities of individual secondary structural elements, residue Pro86 in an alpha-helix in phage T4 lysozyme was replaced by ten different amino acids. The x-ray crystal structures of seven of the mutant lysozymes were determined at high resolution. In each case, replacement of the proline resulted in the formation of an extended alpha-helix. This involves a large conformational change in residues 81 to 83 and smaller shifts that extend 20 angstroms across the protein surface. Unexpectedly, all ten amino acid substitutions marginally reduce protein thermostability. This insensitivity of stability to the amino acid at position 86 is not simply explained by statistical and thermodynamic criteria for helical propensity. The observed conformational changes illustrate a general mechanism by which proteins can tolerate mutations.  相似文献