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Grober-Dunsmore Rikki Frazer Thomas K. Beets James P. Lindberg William J. Zwick Paul Funicelli Nicholas A. 《Landscape Ecology》2007,23(1):37-53
Management of tropical marine environments calls for interdisciplinary studies and innovative methodologies that consider processes occurring over broad spatial scales. We investigated relationships between landscape structure and reef fish assemblage structure in the US Virgin Islands. Measures of landscape structure were transformed into a reduced set of composite indices using principal component analyses (PCA) to synthesize data on the spatial patterning of the landscape structure of the study reefs. However, composite indices (e.g., habitat diversity) were not particularly informative for predicting reef fish assemblage structure. Rather, relationships were interpreted more easily when functional groups of fishes were related to individual habitat features. In particular, multiple reef fish parameters were strongly associated with reef context. Fishes responded to benthic habitat structure at multiple spatial scales, with various groups of fishes each correlated to a unique suite of variables. Accordingly, future experiments should be designed to test functional relationships based on the ecology of the organisms of interest. Our study demonstrates that landscape-scale habitat features influence reef fish communities, illustrating promise in applying a landscape ecology approach to better understand factors that structure coral reef ecosystems. Furthermore, our findings may prove useful in design of spatially-based conservation approaches such as marine protected areas (MPAs), because landscape-scale metrics may serve as proxies for areas with high species diversity and abundance within the coral reef landscape.
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Paratuberculosis in a mandrill (Papio sphinx). 总被引：3，自引：0，他引：3
Laura S Zwick Timothy F Walsh Robyn Barbiers Michael T Collins Michael J Kinsel Robert D Murnane 《Journal of veterinary diagnostic investigation》2002,14(4):326-328
A 2.5-year-old captive female mandrill (Papio sphinx) died following a protracted course of intermittent abdominal bloat, diarrhea, and severe weight loss. Necropsy revealed emaciation and marked gastrointestinal distention with gas and ingesta. Histologic evaluation revealed severe diffuse granulomatous enterocolitis and mesenteric lymphadenitis with massive numbers of 1-2-microm acid-fast bacilli within macrophages. Additionally, there was moderate to severe multifocal myocardial and vascular amyloidosis, moderate multifocal pyogranulomatous interstitial pneumonia with no acid-fast bacteria, and moderate multifocal glossal candidiasis. Samples of feces, ileum, and colon were positive for Mycobacterium avium subsp. paratuberculosis by radiometric culture and a polymerase chain reaction-amplified DNA probe specific for the insertion sequence IS900 of this organism. 相似文献
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R. G. Lehmann C. L. Frye D. A. Tolle T. C. Zwick 《Water, air, and soil pollution》1996,87(1-4):231-243
Our previous publications showed that silicone (polydimethylsiloxane, or PDMS) polymers degrade to monomeric silanols and eventually to C02 in laboratory soil incubations. In this study, 200 cs14C-PDMS was added to soil microcosms (Tuscola sandy loam and Fargo silty clay) in anaerobically digested sludge. Soybeans followed by wheat were grown for 7 months during which microcosms were subjected to 3 leaching events. Recoveries of14C in the microcosms ranged from 47 to 90%. The recovered14C was almost completely in the soils, with trace amounts in leachate and ≤ 2% of the total in plant shoots. Extraction of soils coupled with HPLC-GPC showed that the majority of soill4C was still polymeric, but with lower molecular weight than the original PDMS. From 1 to 5% of the remaining14C was probably small silanols. Results thus confirm laboratory studies and show that PDMS degradation occurs under conditions similar to the field. 相似文献
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Voit J Perfetti L Zwick F Berger H Margaritondo G Grüner G Höchst H Grioni M 《Science (New York, N.Y.)》2000,290(5491):501-503
When electrons are subject to a potential with two incommensurate periods, translational invariance is lost, and no periodic band structure is expected. However, model calculations based on nearly free one-dimensional electrons and experimental results from high-resolution photoemission spectroscopy on a quasi-one-dimensional material do show dispersing band states with signatures of both periodicities. Apparent band structures are generated by the nonuniform distribution of electronic spectral weight over the complex eigenvalue spectrum. 相似文献
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Saphire EO Parren PW Pantophlet R Zwick MB Morris GM Rudd PM Dwek RA Stanfield RL Burton DR Wilson IA 《Science (New York, N.Y.)》2001,293(5532):1155-1159
We present the crystal structure at 2.7 angstrom resolution of the human antibody IgG1 b12. Antibody b12 recognizes the CD4-binding site of human immunodeficiency virus-1 (HIV-1) gp120 and is one of only two known antibodies against gp120 capable of broad and potent neutralization of primary HIV-1 isolates. A key feature of the antibody-combining site is the protruding, finger-like long CDR H3 that can penetrate the recessed CD4-binding site of gp120. A docking model of b12 and gp120 reveals severe structural constraints that explain the extraordinary challenge in eliciting effective neutralizing antibodies similar to b12. The structure, together with mutagenesis studies, provides a rationale for the extensive cross-reactivity of b12 and a valuable framework for the design of HIV-1 vaccines capable of eliciting b12-like activity. 相似文献
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L S Zwick M B Briggs S S Tunev C A Lichtensteiger R D Murnane 《Journal of zoo and wildlife medicine》2000,31(2):211-214
Two captive California sea lions (Zalophus californianus) from different facilities were diagnosed with disseminated blastomycosis. The first, a 12-yr-old male, died after a 3-wk history of progressive anorexia and lethargy. Gross examination revealed acute jejunitis with focal perforation and associated peritonitis, along with severe purulent bronchopneumonia. The second, a 15-yr-old female, was euthanized after a 2-wk history of severe cutaneous ulceration and declining clinical condition. Gross examination revealed severe pyogranulomatous bronchopneumonia and ulcerative dermatitis. Histopathologic examination in both individuals revealed severe multifocal subacute to chronic pyogranulomatous pneumonia associated with massive numbers of fungal organisms morphologically compatible with Blastomyces sp. Fungal organisms were 8-20-microm-diameter broad-based budding yeasts with thick, refractile, double-contoured walls. The male sea lion had multifocal transmural Blastomyces-induced enteritis with subsequent rupture and peritonitis. The organism was also present in the liver, with minimal associated inflammation. The female had severe multifocal pyogranulomatous ulcerative dermatitis associated with large numbers of intralesional fungal organisms. Dissemination to the spleen had occurred in both animals. A serologic immunodiffusion test for Blastomyces dermatitidis was positive in the male. The presumptive primary pathogen in both cases was Blastomyces dermatitidis. 相似文献
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M. F. Arthur T. C. Zwick D. A. Tolle P. Van Voris 《Water, air, and soil pollution》1984,22(2):209-211
Unweathered, acidic fly ash from a coal-fired power plant was applied to alfalfa meal-amended agricultural soil at levels equivalent to 0, 100, 400, and 700 tonne ha?1. Amended soils were placed in respirometer jars and monitored for C02-C evolution over a 37-day period. Fly ash applications of 400 and 700 tonne ha?1 reduced C02-C production significantly compared to 0 and 100 tonne ha?1 treatments. Carbon dioxide-carbon from all treatments was considerably greater than that from soil treated with 1000 ppm CdCl2. The results suggest that soil heterotrophic microbial activity may be impacted minimally by relatively low levels of fly ash application, but may be inhibited by higher levels of fly ash. Several metals were present at potentially toxic levels in the fly ash employed and may have accounted for the inhibition of CO2 C evolution. The availability of some of these metals was indicated in companion plant uptake experiments. 相似文献