Seasonality and elevational migration in an Andean bird community

Title from PDF of title page (University of Missouri--Columbia, viewed on June 4, 2010).The entire thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file; a non-technical public abstract appears in the public.pdf file.Dissertation advisor: Dr. John Faaborg.Vita.Ph. D. University of Missouri--Columbia 2010.Life history strategies of many birds in the Neotropics remain poorly known. In particular, details on the seasonal movements of individuals and populations within the Neotropics remain largely unknown, including short-distance movements along elevational gradients, known as altitudinal or elevational migration. Here I provide the first community-level assessment of avian elevational migration in South America. I used point counts, mist netting, focal observations of a mid-elevation mixed species flock to document the phenology and elevational movements of birds along a 2.7 km elevational gradient in Manu National Park, southeastern Peru. Breeding for most species started with the onset of the rainy season in September and peaked in November, while molt peaked in February. The timing of elevational migration varied. Using multiple field methods and analyses, I classified 55 species as elevational migrants and 169 as residents. Insectivores were more likely to be resident, while other foraging guilds were more likely to be migratory. Migrants molted more quickly than residents. The most abundant species during the dry season in the mid-elevation mixed-species flock were elevational migrants, suggesting a possible relationship between elevational migration and mixed-species flocking. The percentage of elevational migrants along the entire elevational gradient was higher than at Central American sites of similar latitude in the northern hemisphere, affirming a north-south geographic pattern of an increasing percentage of elevational migrants in bird communities. My results fill in an information gap on bird migration in the South America and provide a method of quantifying distributions along environmental gradients that can be applied to other taxa and gradients. Effective conservation of Andean ecosystems should include protection of complete elevational gradients, particularly given the uncertainties associated with future climate change.Includes bibliographical references

Influence of daily oral prophylactic selenium treatment on the dibutyltin dichloride (DBTC)-induced pancreatitis in rats

Dibutyltin dichloride (DBTC) is an organotin compound used as model for acute and chronic pancreatitis. Oxidative stress is one of the mechanisms of propagation of acinar cell injury in acute pancreatitis. Selenium is an essential cofactor in the antioxidant glutathione peroxidase pathway. Selenium levels are described to be subnormal in patients with acute and chronic pancreatitis. The aim of our studies was to determine the prophylactic effect of Na-selenite [5 mg kg-1 body weight (b.w.) per os (p.o.) 7 days] on the pathogenesis and course of DBTCinduced pancreatitis. Male inbred rats (LEW-1W Charles River) of 150 g body weight were used in this study. Experimental pancreatitis was induced by intravenous administration of 6 mg kg-1 b.w. DBTC in rats. Na-selenite was administered as daily oral dose of 5 mg kg-1 b.w. 7 days before induction of DBTC-pancreatitis. Malondialdehyde (MDA) was measured for monitoring levels of oxidative stress. Elimination of DBTC was reflected as tin concentration in bile and urine. Organ changes were indicated by serum parameters as well as histology. A prophylactic Na-selenite application significantly diminished MDA- and bilirubin concentration in serum, activities of lipase and transaminases as well as organ injuries compared to DBTC- treated rats in the absence of Naselenite. The prophylactic oral treatment with Na-selenite in the scope of DBTC-induced pancreatitis points to a reduced oxidative stress characterized by diminished MDA serum levels and a milder course of pancreatitis suggesting prophylactic substitution with Na-selenite to probably elicit beneficial effect on the clinical outcome in patients with endoscopic retrograde cholangiopancreatography (ERCP)

Dibutyltin Disrupts Glucocorticoid Receptor Function and Impairs Glucocorticoid-Induced Suppression of Cytokine Production

BACKGROUND: Organotins are highly toxic and widely distributed environmental chemicals. Dibutyltin (DBT) is used as stabilizer in the production of polyvinyl chloride plastics, and it is also the major metabolite formed from tributyltin (TBT) in vivo. DBT is immunotoxic, however, the responsible targets remain to be defined. Due to the importance of glucocorticoids in immune-modulation, we investigated whether DBT could interfere with glucocorticoid receptor (GR) function. METHODOLOGY: We used HEK-293 cells transiently transfected with human GR as well as rat H4IIE hepatoma cells and native human macrophages and human THP-1 macrophages expressing endogenous receptor to study organotin effects on GR function. Docking of organotins was used to investigate the binding mechanism. PRINCIPAL FINDINGS: We found that nanomolar concentrations of DBT, but not other organotins tested, inhibit ligand binding to GR and its transcriptional activity. Docking analysis indicated that DBT inhibits GR activation allosterically by inserting into a site close to the steroid-binding pocket, which disrupts a key interaction between the A-ring of the glucocorticoid and the GR. DBT inhibited glucocorticoid-induced expression of phosphoenolpyruvate carboxykinase (PEPCK) and tyrosine-aminotransferase (TAT) and abolished the glucocorticoid-mediated transrepression of TNF-alpha-induced NF-kappaB activity. Moreover, DBT abrogated the glucocorticoid-mediated suppression of interleukin-6 (IL-6) and TNF-alpha production in lipopolysaccharide (LPS)-stimulated native human macrophages and human THP-1 macrophages. CONCLUSIONS: DBT inhibits ligand binding to GR and subsequent activation of the receptor. By blocking GR activation, DBT may disturb metabolic functions and modulation of the immune system, providing an explanation for some of the toxic effects of this organotin

Integrating Malaria Surveillance with Climate Data for Outbreak Detection and Forecasting: the EPIDEMIA System

Background: Early indication of an emerging malaria epidemic can provide an opportunity for proactive interventions. Challenges to the identification of nascent malaria epidemics include obtaining recent epidemiological surveillance data, spatially and temporally harmonizing this information with timely data on environmental precursors, applying models for early detection and early warning, and communicating results to public health officials. Automated web-based informatics systems can provide a solution to these problems, but their implementation in real-world settings has been limited. Methods: The Epidemic Prognosis Incorporating Disease and Environmental Monitoring for Integrated Assessment (EPIDEMIA) computer system was designed and implemented to integrate disease surveillance with environmental monitoring in support of operational malaria forecasting in the Amhara region of Ethiopia. A co-design workshop was held with computer scientists, epidemiological modelers, and public health partners to develop an initial list of system requirements. Subsequent updates to the system were based on feedback obtained from system evaluation workshops and assessments conducted by a steering committee of users in the public health sector.Results: The system integrated epidemiological data uploaded weekly by the Amhara Regional Health Bureau with remotely-sensed environmental data freely available from online archives. Environmental data were acquired and processed automatically by the EASTWeb software program. Additional software was developed to implement a public health interface for data upload and download, harmonize the epidemiological and environmental data into a unified database, automatically update time series forecasting models, and generate formatted reports. Reporting features included district-level control charts and maps summarizing epidemiological indicators of emerging malaria outbreaks, environmental risk factors, and forecasts of future malaria risk. Conclusions: Successful implementation and use of EPIDEMIA is an important step forward in the use of epidemiological and environmental informatics systems for malaria surveillance. Developing software to automate the workflow steps while remaining robust to continual changes in the input data streams was a key technical challenge. Continual stakeholder involvement throughout design, implementation, and operation has created a strong enabling environment that will facilitate the ongoing development, application, and testing of the system