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Theses/Dissertations

2011

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Full-Text Articles in Life Sciences

Consequences Of Stochastic Mrna Synthesis In A Gene Regulatory Pathway, Khyati Shah Dec 2011

Consequences Of Stochastic Mrna Synthesis In A Gene Regulatory Pathway, Khyati Shah

Dissertations

Gene expression is a stochastic process, with elements of randomness present in both transcription and translation. This stochasticity results in cell-to-cell variation in the amounts of gene products, mRNAs and proteins, and is observed in organisms ranging from bacteria and yeast to higher eukaryotes. Randomness in the activation and inactivation of a gene is the preliminary cause of this variation. At the level of proteins, these variations are buffered compared to levels of mRNA, due to the longer lifespan of proteins. Nevertheless, there is substantial variation observed at the level of proteins, resulting in phenotypic diversity among genetically identical cells ...


The Role Of Adaptive Stress Responses In Hiv Replication And Macrophage-Mediated Neurotoxicity, Stephanie Cross Dec 2011

The Role Of Adaptive Stress Responses In Hiv Replication And Macrophage-Mediated Neurotoxicity, Stephanie Cross

Publicly Accessible Penn Dissertations

Despite antiretroviral therapy (ART), HIV infection promotes cognitive dysfunction and neurodegeneration through persistent inflammation and neurotoxin release from infected and/or activated macrophages. Inflammation and immune activation within both the central nervous system (CNS) and periphery correlate with disease progression and morbidity in ART-treated individuals. Accordingly, drugs targeting these pathological processes are needed for effective, adjunctive therapy. Using our in vitro model of HIV-mediated neurotoxicity, in which HIV infected monocyte-derived macrophages (HIV/MDM) release excitatory neurotoxins, we demonstrate that HIV infection dysregulates adaptive stress responses, including the antioxidant response and the unfolded protein response (UPR). HIV infected macrophages have dramatic ...


Innate Signals In The Macrophage Determine The Severity Of Toxoplasma Gondii Infection, Ryan J. Whitmarsh Dec 2011

Innate Signals In The Macrophage Determine The Severity Of Toxoplasma Gondii Infection, Ryan J. Whitmarsh

Publicly Accessible Penn Dissertations

Toxoplasma gondii is an obligate intracellular pathogen that is a cause of significant morbidity and mortality in humans and animals. The immune response necessary to control this infection requires successful coordination of strong innate and adaptive responses. Recognition of the pathogen by innate accessory cells such as macrophages, neutrophils, and dendritic cells induces the release of IL-12 that activates NK and T cells to produce protective IFN-g, the major mediator of immunity to T. gondii. T. gondii has many mechanisms to limit the activation of innate cells and to reduce the production of IL-12. One of the ways T. gondii ...


Inhaled Oxygen As A Quantitative Intravascular Mri Contrast Agent, David T. Pilkinton Dec 2011

Inhaled Oxygen As A Quantitative Intravascular Mri Contrast Agent, David T. Pilkinton

Publicly Accessible Penn Dissertations

Increasing the fraction of inspired oxygen (FiO2) generates MR contrast by two distinct mechanisms: increased T2 from deoxyhemoglobin dilution in venous compartments (blood oxygenation level-dependent effect or BOLD) and reduced T­1 from paramagnetic molecular oxygen dissolved in blood plasma and tissues. Many research and clinical applications using hyperoxic contrast have recently emerged, including delineating ischemic stroke penumbra, oxygen delivery to tumors, and functional MRI data calibration. However, quantitative measurements using this contrast agent depend on the precise knowledge of its effects on the MR signal – of which there remain many crucial missing pieces.

This thesis aims to ...


Evolution Of Molecular Function In Mammalian Neurons, Chantal Francis Dec 2011

Evolution Of Molecular Function In Mammalian Neurons, Chantal Francis

Publicly Accessible Penn Dissertations

A common question in neuroscience is what forms the neurological basis of the variety of behaviors in mammals. While many studies have compared mammalian anatomy and evolution, few have investigated the physiologic functions of individual neurons in a comparative manner. Neurons’ ability to modify their features in response to stimuli, known as synaptic plasticity, is fundamental for learning and memory. A key feature of synaptic plasticity involves delivering mRNA to distinct domains where they are locally translated. Regulatory coordination of these events is critical for synaptogenesis and synaptic plasticity as defects in these processes can lead to neurological diseases. In ...


Dynamic Vertical Climbing: Bioinspiration, Design, And Analysis, Goran Lynch Dec 2011

Dynamic Vertical Climbing: Bioinspiration, Design, And Analysis, Goran Lynch

Publicly Accessible Penn Dissertations

Biologists have proposed a pendulous climbing model, the Full-Goldman (F-G) template, that abstracts remarkable similarities in dynamic wall scaling behavior exhibited by radically different animal species. This thesis presents a progression of work related to dynamic vertical climbing based on that model.

We begin by describing the inspiration, design, implementation of and experimentation with the first dynamical vertical climbing robot. We study numerically a version of the pendulous climbing template dynamically re-scaled for applicability to utilitarian payloads with conventional electronics and actuation, revealing that the incorporation of passive compliance can compensate for an artifact’s poorer power density and scale ...


A Cross-Sectional Study Of Vitamin D, Glycemic Control, And Inflammatory Cytokines In Children And Adolescents With Type 1 Diabetes Mellitus, Sarah Al Sawah Dec 2011

A Cross-Sectional Study Of Vitamin D, Glycemic Control, And Inflammatory Cytokines In Children And Adolescents With Type 1 Diabetes Mellitus, Sarah Al Sawah

Publicly Accessible Penn Dissertations

Background: Vitamin D deficiency is markedly prevalent in children and adolescents with type 1 diabetes mellitus (T1DM). Despite accumulating evidence to support the link between vitamin D deficiency and both impaired glucose metabolism and altered immune responses in vitro and in vivo, it is not known whether vitamin D deficiency is linked to poor glycemic control and/or systemic levels of inflammatory cytokines in children and adolescents with T1DM. Aims: The purpose of this study was to examine the relationship between 25-hydroxyvitamin D (the functional indicator of vitamin D status) and HbA1c (the standardized index of glycemic control); and to ...


The Functional Biology Of Il-25, Steven A. Saenz Dec 2011

The Functional Biology Of Il-25, Steven A. Saenz

Publicly Accessible Penn Dissertations

CD4+ T helper (Th) 2 cells secrete interleukin (IL)-4, IL-5 and IL-13 and promote immunity to gastrointestinal helminth infections and chronic inflammation associated with asthma and allergic disorders. However, the innate immune pathways that promote Th2 cell responses remain poorly characterized. The non-hematopoietic cell-derived cytokines thymic stromal lymphopoietin (TSLP), IL-33 and IL-25 (IL-17E) have been implicated in promoting Th2 cell-dependent inflammation at mucosal sites [1-4], but how these cytokines influence innate immune responses are less well defined. Studies in Chapter 2 and 3 examined the cellular mechanisms through which IL-25 promotes Th2 cell responses and demonstrated that IL-25 promotes ...


Genetic Polymorphisms And Antifolate Drug Treatment Can Alter Folate/Homocysteine Metabolism And Inflammatory Protein Profile, Andrea L. Hammons Dec 2011

Genetic Polymorphisms And Antifolate Drug Treatment Can Alter Folate/Homocysteine Metabolism And Inflammatory Protein Profile, Andrea L. Hammons

Publicly Accessible Penn Dissertations

The folate metabolic pathway is important in several biological processes, including purine and pyrimidine synthesis and the methylation of DNA and proteins. There are several pathologies that are associated with dysregulation of the folate/homocysteine (Hcy) metabolic pathway, including rheumatoid arthritis (RA), cardiovascular disease (CVD), and several cancers. Many of the pathologies associated with altered folate/Hcy metabolism have underlying inflammatory etiology. The distribution of folate derivatives can be influenced by nutrient deficiency or insufficiency and by genetic polymorphisms in important enzymes in the pathway. Additionally, antifolate drugs, such as methotrexate (MTX) and pemetrexed (PMX), modify folate/Hcy metabolism.

The ...


Regional Lysosomal Malfunction Underlies The Selectivity Of Α-Synuclein Neurodegeneration, Kristen A. Malkus Dec 2011

Regional Lysosomal Malfunction Underlies The Selectivity Of Α-Synuclein Neurodegeneration, Kristen A. Malkus

Publicly Accessible Penn Dissertations

Dysfunction of protein homoeostasis has been implicated in the pathogenesis of a diverse array of neurodegenerative disorders. However, each neurodegenerative disease is characterized by the accumulation of particular proteins in select regions of the brain. It remains unclear how dysfunction of a ubiquitous protein degradation pathway results in distinct pathologies. α-Synuclein is a protein whose aggregation and oligomerization has been implicated in several diseases, including Parkinson’s disease (PD). Herein, we investigated regionally selective alterations in α-synuclein degradation to decipher potential mechanisms underlying its role in disease. Chaperone mediated autophagy (CMA), a selective route of direct lysosomal degradation, participates in ...


Development Of Natural Killer Cells Regulated By T-Box Transcription Factors, Scott M. Gordon Dec 2011

Development Of Natural Killer Cells Regulated By T-Box Transcription Factors, Scott M. Gordon

Publicly Accessible Penn Dissertations

Natural killer (NK) cells play critical roles in host defense against tumors and intracellular pathogens. Various transcription factors have been reported to alter NK cell development, but the definitive transcriptional program governing this process is not well understood. Our laboratory has shown previously that the T-box transcription factors T-bet and Eomesodermin (Eomes) direct fate and function in cytotoxic T lymphocytes. We thus endeavored to define the roles of T-bet and Eomes in the differentiation of NK cells. We find that NK progenitor cells give rise to immature-phenotype NK cells, which express the death ligand TRAIL and the transcription factor T-bet ...


Interleukin-22 Regulates Immunity, Inflammation And Tissue Homeostasis At Mucosal Sites, Gregory Field Sonnenberg Dec 2011

Interleukin-22 Regulates Immunity, Inflammation And Tissue Homeostasis At Mucosal Sites, Gregory Field Sonnenberg

Publicly Accessible Penn Dissertations

At mucosal sites, a single layer of epithelial cells separates the connective tissues of the mammalian body from the external environment. The gastrointestinal tract is the largest mucosal surface exposed to the environment and is colonized with an estimated 300 trillion beneficial commensal bacteria. These properties of mucosal sites help facilitate critical biological processes, including nutrient absorption, gas exchange and excretion of wastes, yet also renders mucosal sites particularly vulnerable to infection and inflammation. In order to maintain a state of health, complex immunoregulatory networks have evolved at mucosal sites to promote immunity, limit inflammation and maintain tissue homeostasis. Interleukin ...


A Notch Above Bowl: Specification Of Niche Cells In The Drosophila Testis, Tishina C. Okegbe Dec 2011

A Notch Above Bowl: Specification Of Niche Cells In The Drosophila Testis, Tishina C. Okegbe

Publicly Accessible Penn Dissertations

Niche cells exercise elaborate control over the behavior of many tissue-specific stem cells. However, in no system do we fully understand how niche cells are specified, develop and then begin producing the signals necessary to properly regulate stem cells. Here, we take advantage of the paradigmatic stem cell-niche system of the Drosophila testis to address these fundamental questions. We first find that the Notch signaling pathway is necessary for niche cell specification and that its activity in precursor cells prevents those cells from adopting the alternative somatic cyst cell fate. We also discover that the Notch-activating ligand, Delta, is presented ...


The Cytoskeletal Mechanisms Of Cell-Cell Junction Formation In Endothelial Cells, Matthew K. Hoelzle Dec 2011

The Cytoskeletal Mechanisms Of Cell-Cell Junction Formation In Endothelial Cells, Matthew K. Hoelzle

Publicly Accessible Penn Dissertations

Intercellular adhesions are essential for compartmentalization and integrity of tissues in an organism, cell-cell communication, and morphogenesis. The actin cytoskeleton and associated proteins play a vital role in establishing and maintaining cell-cell adhesion. However, the procedure by which cells establish adherens junctions remains largely unclear.

We investigated the dynamics of cell-cell junction formation and the corresponding architecture of the underlying cytoskeleton in cultured human umbilical vein endothelial cells (HUVECs). We show that the initial interaction between cells is mediated by protruding lamellipodia. Upon their retraction, cells maintain contact through thin bridges formed by filopodia-like protrusions connected by VE-cadherin-rich junctions.

Bridges ...


Intestine Homeostasis And The Role Of Tumor Suppressor Gene 101 In Drosophila Melanogaster: A Dissertation, Madhurima Chatterjee Dec 2011

Intestine Homeostasis And The Role Of Tumor Suppressor Gene 101 In Drosophila Melanogaster: A Dissertation, Madhurima Chatterjee

GSBS Dissertations and Theses

Tissue homeostasis in the adult Drosophila melanogaster intestine is maintained by controlling the proper balance of stem cell self-renewal and differentiation. In the adult fly midgut, intestinal stem cells (ISCs) are the only dividing cells and their identity maintenance is crucial to the proper functioning of the fly gut. Various pathways such as Notch, JAK-STAT and Wingless are known to regulate ISC division and differentiation.

Here I used a pathogen feeding model to study conditions that accelerate ISC division and guide intestinal cell differentiation favoring enterocyte development. I also examined the role of Tumor Suppressor Gene 101 (TSG101) in ISC ...


Design And Synthesis Of Cationic Steroid Antimicrobial Compounds, Synthesis Of Glycolipids Recognized By Natural Killer T Cells And Development Of Tlr-1, Tlr-6 Heterodimer Binders And Studies Of Their Immunology Activities, Yanshu Feng Dec 2011

Design And Synthesis Of Cationic Steroid Antimicrobial Compounds, Synthesis Of Glycolipids Recognized By Natural Killer T Cells And Development Of Tlr-1, Tlr-6 Heterodimer Binders And Studies Of Their Immunology Activities, Yanshu Feng

Theses and Dissertations

Cationic steroid antimicrobial agents (CSAs) are a family of bile acid derivatives. These compounds are amphiphilic and mimic endogenous antimicrobial peptides. The antimicrobial activities of CSA-13 have been investigated and due to portent bactericidal activities and low toxicity, a large amount of CSA-13 is demanded for clinic trails and other antimicrobial applications. During our studies, we optimized the synthetic route of CSA-13, so that it can be prepared at the kilogram, even in tons scale. We investigated three routes and one of them is suitable for industry, because only recrystallization is needed in the synthesis. Natural killer T cells (NKT ...


Septotemporal Variation In Theta Rhythm Dynamics: Effects Of Speed And Habituation, James Hinman Dec 2011

Septotemporal Variation In Theta Rhythm Dynamics: Effects Of Speed And Habituation, James Hinman

Master's Theses

Theta (6-12 Hz) field potentials and the synchronization (coherence) of these potentials present neural network indices of hippocampal physiology. Theta signals within the hippocampal formation may reflect alterations in sensorimotor integration, the flow of sensory input and/or distinct cognitive operations. While the power and coherence of theta signals vary across lamina within the septal hippocampus, limited information is available about variation in these indices across the septotemporal (long) or areal axis. The present study examined the relationship of locomotor speed to theta indices at CA1 and DG sites across the septotemporal axis as well as in the entorhinal cortex ...


Design Of A Tetracycline Operon Inducible System For The Control Of Vaccinia Virus Replication: Implications For Vaccine Development, Caitlin J. Hagen Dec 2011

Design Of A Tetracycline Operon Inducible System For The Control Of Vaccinia Virus Replication: Implications For Vaccine Development, Caitlin J. Hagen

Master's Theses

The use of vaccinia virus (VACV) as a vaccine resulted in the eradication of smallpox in 1979. Characteristics that contribute to the effectiveness of VACV as a vaccine and viral vector include its ability to elicit strong, long-lived humoral and cell-mediated immune responses as a live-replicating virus and to accept large inserts of DNA into its genome. However, adverse events associated with its use as the smallpox vaccine have constrained it from being more widely utilized in vaccines and therapies. We propose to improve the safety of VACV as a live-replicating vector by using elements of the tet operon to ...


Psychometric Evaluation Of The Timeline Followback For Exercise Among Young Adults, Gregory A. Panza Dec 2011

Psychometric Evaluation Of The Timeline Followback For Exercise Among Young Adults, Gregory A. Panza

Master's Theses

Objectives: Two separate studies assessed psychometric properties of a retrospective behavioral measure adapted for exercise called the Timeline Followback for Exercise (TLFB-E). Study one examined criterion, convergent, and predictive validity. Study two examined test-retest reliability. Methods: Study one participants (N = 66) were college students 20.0 ± 1.4yr. Validity of frequency, intensity, time, and type of exercise as assessed on the TLFB-E was examined using Pearson r correlations with accelerometers, weekly exercise contracts between participants and researchers, College Alumni Questionnaire, and a health-related physical fitness battery. Study two participants were a separate sample (N = 40) of college students 18.63 ...


An Assessment Of Moose (Alces Alces Americana) And Moose Management In Connecticut, Andrew M. Labonte Dec 2011

An Assessment Of Moose (Alces Alces Americana) And Moose Management In Connecticut, Andrew M. Labonte

Master's Theses

Eastern moose (Alces alces americana) populations have been increasing in New England over the past decade. Moose populations have the potential to generate human conflict due to their size, speed, nocturnal behavior, and seasonal mobility. As problems associated with increasing moose populations become more common, the need to develop management strategies that are both effective and acceptable to stakeholders becomes increasingly important. The potential for moose to continue to expand in southern New England and the long-term impacts they may have on Connecticut residents, is unclear. The overall purpose of this study was to assess how suitable Connecticut is for ...


Effects Of 4-Hydroxy-2-Nonenal On Mutant Sperm Whale Myoglobins, Nantawat Tatiyaborworntham Dec 2011

Effects Of 4-Hydroxy-2-Nonenal On Mutant Sperm Whale Myoglobins, Nantawat Tatiyaborworntham

Master's Theses

No abstract provided.


Role Of Pseudomonas Produced Hydrogen Cyanide In Biological Control Of Plant-Parasitic Nematodes, Haytham Aly Dec 2011

Role Of Pseudomonas Produced Hydrogen Cyanide In Biological Control Of Plant-Parasitic Nematodes, Haytham Aly

Dissertations

Plant-parasitic nematodes are among the most devastating pests world-wide, causing extensive damage to important agriculture crops. The management of nematodes is challenging. Current methods used for nematode control rely mostly on using chemical nematicides and naturally resistant plants. Because of serious health and environmental problems associated with chemical control and over use of resistant plants resulting in resistant breaking strains of nematodes, alternative nematode-control methods are needed. Several potential nematode-biocontrol agents, including bacteria and fungi, have been studied for their antagonistic effect toward plant-parasitic nematodes. However, a concise picture about the biological agent’s mechanisms used to antagonize nematodes remains ...


Pedometers Accelerometers And Observational Methods: A Comparison Of Measurements Of Physical Activity In Fourth-Grade Students., Amanda E. Greene Dec 2011

Pedometers Accelerometers And Observational Methods: A Comparison Of Measurements Of Physical Activity In Fourth-Grade Students., Amanda E. Greene

Electronic Theses and Dissertations

In recent years physical inactivity among students has become a matter of great concern. Nearly 65% of students do not meet the daily recommended level of physical activity, which is 60 minutes or more of moderate to vigorous physical activity each day, with 50% of that time being spent in moderate to vigorous levels of activity (CDC, 2010b). As a result, the 21st century has shown to be a time of many health problems such as, obesity, diabetes, and heart disease. In fact, nearly one third of all children are considered obese or overweight (Slawta & DeNeui, 2009). Researchers ...


The Role Of The Nascent Polypeptide-Associated Complex In Caenorhabditis Elegans, Paul T. Arsenovic Dec 2011

The Role Of The Nascent Polypeptide-Associated Complex In Caenorhabditis Elegans, Paul T. Arsenovic

Masters Theses

The nascent polypeptide-associated complex (NAC) is a highly conserved protein complex known to play an important role in the development of metazoan organisms, but its molecular function is not well understood. Recent evidence from experiments using Saccharomyces cerevisiae as model supported the hypothesis that the NAC is either a chaperone or a component of the cytosolic chaperone network that interacts with nascent peptides emerging from the ribosome. We tested this model in C. elegans and found that the homologues of the NAC , icd-1 and icd-2, behave like chaperones in the worm. Lack of icd-1 or icd-2 altered the worms stress ...


A Case Study In Wetlands Conservation: Identifying Best Management Practices For Landowner Stewardship, Allison M. Bredbenner Dec 2011

A Case Study In Wetlands Conservation: Identifying Best Management Practices For Landowner Stewardship, Allison M. Bredbenner

Masters Theses

This research explores wetlands conservation techniques employed by private landowners owning 1,000 or more acres who were recipients of an Environmental Law Institute National Wetlands Award. Study of private landowner stewardship is timely and important because in the United States, 75 percent of all wetlands are under private ownership. Given that wetlands provide a suite of valuable ecosystem services such as water filtration, flood abatement, and carbon storage, their conservation is critical to a healthy environment and productive economy. To accomplish this research, landowner files were processed into a digital archive and sub-categorized for research purposes. Telephone interviews were ...


A Technology Assessment Of On-Farm Renewable Energy Carbon Mitigation Strategies, Laura Kossey Dec 2011

A Technology Assessment Of On-Farm Renewable Energy Carbon Mitigation Strategies, Laura Kossey

Masters Theses

This project explores whether the Shenandoah Valley can achieve its 25x.25 (25% from renewable energies by 2025) goals on farms in the agricultural sector. Solar photovoltaic electric power production was assessed to be the most feasible renewable energy technology for such farms. After a review of the barriers to the adoption of renewable energy by agricultural operations, estimations of the potential rates of adoption and energy output using US data from the US Census of Agriculture were calculated. Multiple scenarios were explored, including the ¡°maximum theoretical¡± contribution of renewable energy to the agricultural sector as well as scenarios of ...


Synthesis Of Resveratrol Esters And Aliphatic Acids., Stanley Mofor Jing Dec 2011

Synthesis Of Resveratrol Esters And Aliphatic Acids., Stanley Mofor Jing

Electronic Theses and Dissertations

Resveratrol (RV) is a naturally occurring phytoalexin of the stilbenoid family produced by some plant species, and present in grape skin, peanuts, and red wine. It has been found to exhibit anti-cancer, anti-inflammatory, anti-viral, anti-aging, cardio protective, and anti-oxidant properties. Bioavailability is a huge setback that limits the potentials of RV. As a result, efforts have been made to design and synthesize RV esters and aliphatic acids in an attempt to increase its bioavailability, solubility in water, and possibly improving its biological activities. Resveratrol esters, 3,5,4'-triacetyloxystilbene (2) and Methyl 1,1',1''- (3,4',5-stilbenyl)-1,6-hexanedioate ...


Isolation Of A Rhodococcus Soil Bacterium That Produces A Strong Antibacterial Compound., Ralitsa Bogomilova Borisova Dec 2011

Isolation Of A Rhodococcus Soil Bacterium That Produces A Strong Antibacterial Compound., Ralitsa Bogomilova Borisova

Electronic Theses and Dissertations

Rhodococci are notable for their ability to degrade a variety of natural and xenobiotic compounds. Recently, interest in Rhodococcus has increased due to the discovery of a large number of genes for secondary metabolism. Only a few secondary metabolites have been characterized from the rhodococci (including 3 recently described antibiotics). Twenty-four new Rhodococcus strains were isolated from soils in East Tennessee using acetonitrile enrichment culturing and identified using 16S rRNA analysis. Forty-seven Rhodococcus strains were screened for antibiotic production using a growth inhibition assay. One strain, MTM3W5.2, had 90% similarity to the Rhodococcus opacus 16S rRNA gene sequence and ...


Multivariate Models And Algorithms For Systems Biology, Lipi Rani Acharya Dec 2011

Multivariate Models And Algorithms For Systems Biology, Lipi Rani Acharya

University of New Orleans Theses and Dissertations

Rapid advances in high-throughput data acquisition technologies, such as microarraysand next-generation sequencing, have enabled the scientists to interrogate the expression levels of tens of thousands of genes simultaneously. However, challenges remain in developingeffective computational methods for analyzing data generated from such platforms. In thisdissertation, we address some of these challenges. We divide our work into two parts. Inthe first part, we present a suite of multivariate approaches for a reliable discovery of geneclusters, often interpreted as pathway components, from molecular profiling data with replicated measurements. We translate our goal into learning an optimal correlation structure from replicated complete and incomplete ...


Habitat Characteristics Affecting Site Occupation In Wintering Henslow’S Sparrows At Mississippi Sandhill Crane National Wildlife Refuge, Mary E. Nicholson Dec 2011

Habitat Characteristics Affecting Site Occupation In Wintering Henslow’S Sparrows At Mississippi Sandhill Crane National Wildlife Refuge, Mary E. Nicholson

University of New Orleans Theses and Dissertations

Henslow’s sparrow (Ammodramus henslowii) winters in recently burned sites in pine savannas of the Southeastern United States. Previous studies have suggested that factors such as seed abundance and litter depth are important to wintering Henslow’s sparrows. My study asked how habitat variables including vegetation structure, seed abundance, and arthropod abundance predict Henslow’s sparrow site occupancy at Mississippi Sandhill Crane National Wildlife Refuge. In this study, Henslow’s sparrow more often occupied sites burned one growing season earlier than sites burned two growing seasons earlier, and did not occupy sites burned three or more growing seasons earlier. Data ...