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511.
Summary. Tracer feeding studies with radioactively labeled pyrrolizidine alkaloids (PAs) were performed to attain experimental information about the specificity and mechanisms of uptake, metabolism and storage of PAs in the alkaloid sequestering ithomiine butterfly Mechanitis polymnia. Adult butterflies easily ingest the tracers offered dissolved in a saturated sugar solution. Feeding of [14C]rinderine (free base) confirmed that M. polymnia is well adapted to sequester and maintain PAs of the lycopsamine type. Approximately 80% of the ingested radioactivity can be recovered in methanol extracts of the butterflies over a period of at least 6 hours. Labeled rinderine is efficiently N-oxidized and transformed into a metabolite of still unknown structure. These two metabolites are formed in almost equal amounts and account for more than 90% of total radioactivity. After four hours the toxic free base is only detectable in traces. Radioactively labeled senecioylretronecine (free base), a PA that often accompanies PAs of the lycopsamine type in plants, is metabolized in a different manner. The toxic free base disappeared as fast as the tertiary rinderine, but the final products which accumulated in a stable ratio after 12 hours were mainly two polar metabolites of unknown structure; senecioylretronecine N-oxide accounts for less than 10% of total PAs. Labeled senecionine a macrocyclic PA, which never has been found in wild caught M. polymnia is only slowly N-oxidized. In females ca 50% of the ingested senecionine is still present as free base after 24 hours, whereas under the same conditions in males this percentage is only ca 20%. This difference in N-oxidation was the only significant sex-specific difference observed in various experiments. Larvae of M. polymnia which feed on Solanum tabacifolium, a plant that does not contain PAs, are able to sequester and partly N-oxidize labeled senecioylretronecine and senecionine. However, the storage is not very efficient; with the two tracers less than 5% of radioactivity remained in the bodies after 24 hours. Received 19 October 1999; accepted 24 November 1999  相似文献   
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This paper identifies three models of person-situation interaction in an effort to conceptually clarify and integrate previous research. Statistical criteria for each model are then developed and tested within one organizational setting. Results indicate partial support for each of the three interaction models, and suggest various improvements for person-situation interaction research.  相似文献   
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Temporal and spatial variability in wetland water-quality variables were examined for twenty-one wetlands in the Minneapolis/St. Paul metropolitan area and eighteen wetlands in adjacent Wright County. Wetland water quality was significantly affected by contact with the sediment (surface water vs. groundwater), season, degree of hydrologic isolation, wetland class, and predominant land-use in the surrounding watershed (p<0.05). Between years, only nitrate and particulate nitrogen concentrations varied significantly in Wright County wetland surface waters. For eight water-quality variables, the power of a paired before-and-after comparison design was greater than the power of a completely randomized design. The reverse was true for four other water-quality variables. The power of statistical tests for different classes of water-quality variables could be ranked according to the predominant factors influencing these: climate factors>edaphic factors>detritivory>land-use factors>biotic-redox or other multiple factors.For two wetlands sampled intensively, soluble reactive phosphate and total dissolved phosphorus were the most spatially variable (c.v.=76–249%), while temperature, color, dissolved organic carbon, and DO were least variable (c.v.=6–43%). Geostatistical analyses demonstrated that the average distance across which water-quality variables were spatially correlated (variogram range) was 61–112% of the mean radius of each wetland. Within the shallower of the two wetlands, nitrogen speciation was explained as a function of dissolved oxygen, while deeper marsh water-quality variables were explained as a function of water depth or distance from the wetland edge. Compositing water-quality samples produced unbiased estimates of individual sample means for all water quality variables examined except for ammonium.  相似文献   
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This article discusses a methodology for assessing and rankinga predefined universe of objects to assist in the selectionof suitable areas for the construction of sanitary landfills.The methodology is, in principle, for universal application. Its development was initially based on the `Value Analysis' methodology and then on the `Fuzzy Eigenvector Method', or `Fuzzy Logic' as it is sometimes referred to. The focus of thestudy herein is on the comparative appraisal of a group ofelements which are part of the guidelines to be adopted whendetermining the choice of the most suitable site for a sanitarylandfill. This set of guidelines includes technical, economical,environmental, social and political aspects. As an example of themethodology proposed, four different areas were chosen. They werestudied to determine which is the most appropriate site for thedevelopment of a new solid waste fill site. The results for thesefour areas, together with the functions chosen and functionweights, are presented here.  相似文献   
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Environment, Development and Sustainability - This paper evaluates compliance with environmental laws in the municipality of Sorriso and the impact of changing legislation on vegetation. To verify...  相似文献   
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The main goal of this paper was to explore the relationship between living in industrial areas and individual’s level of psychological health. Using a quasi-experimental design main findings suggest that, regardless of the type of industry that is operating, there was a significant association between living in industrialized areas and decreased levels of well being, optimism and use of active coping strategies. However, results on anxiety and depression were especially high in areas associated with air pollution. Moreover, there was also a significant association between more subjective meanings of place and psychological health. According to a reality-orientation criterion, evidences showed that when individuals live in industrial areas perceptions of their places as industrial are associated with lower depression, anxiety and psychiatric symptoms.  相似文献   
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