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Articles 1471 - 1500 of 1904

Full-Text Articles in Life Sciences

Mda-7/Il-24; A Promising Cancer Therapeutic Agent, Hossein Hamed Jun 2012

Mda-7/Il-24; A Promising Cancer Therapeutic Agent, Hossein Hamed

Theses and Dissertations

Glioblastoma multiforme (GBM) is an aggressive cancer that affects millions of patients per year. Conventional therapies combining chemotherapeutic agents with radiation can only extend survival by a few months; therefore, there is a dire need for an effective means of treating this deadly disease. Melanoma differentiation-associated gene-7/interleukin-24 (mda-7/IL-24), currently in the early stages of FDA pre-IND drug trials, has proven to be an effective cancer specific cytokine, able to trigger the onset of mitochondrial dysfunction and/or autophagy. GBM’s have mutations that often result in the activation of cytoprotective cell signaling pathways, preventing cancer therapeutics and even MDA-7/IL-24 treatments from being …

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The Effect Of Various Chemical Factors On Angiogenesis In The Chick Chorio-Allantoic Membrane, Heather Hammond Jun 2012

The Effect Of Various Chemical Factors On Angiogenesis In The Chick Chorio-Allantoic Membrane, Heather Hammond

Theses and Dissertations

The chick chorio-allantoic membrane (CAM) contains a complex vascular network commonly used to study angiogenesis. The application of chemical factors and oxygen barrier films onto this tissue can easily influence the process of angiogenesis. In this study, oxygen barrier film patches (Krehalon, polyvinylidene chloride, 12 μm thick, O2 transmission rate = 2.19 cm3•ml/100 in2•day•atm) were applied to areas of the CAM. Holes were made in the film and alginate beads incubated in various chemical factors were placed in the holes. After 24 and 48 hours of exposure to the alginate beads, images were taken of the tissue using a stereomicroscope …

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N-Terminal Processing Of Ribosomal Protein L27 In Staphylococcus Aureus, J. Harry Caufield May 2012

N-Terminal Processing Of Ribosomal Protein L27 In Staphylococcus Aureus, J. Harry Caufield

Theses and Dissertations

The bacterial ribosome is essential to cell growth yet little is known about how its proteins attain their mature structures. Recent studies indicate that certain Staphlyococcus aureus bacteriophage protein sequences contain specific sites that may be cleaved by a non-bacteriophage enzyme (Poliakov et al. 2008). The phage cleavage site was found to bear sequence similarity to the N-terminus of S. aureus ribosomal protein L27. Previous studies in E. coli (Wower et al.1998; Maguire et al. 2005) found that L27 is situated adjacent to the ribosomal peptidyl transferase site, where it likely aids in new peptide formation. The predicted S. aureus …

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Impacts Of Rdx Soil Contamination Across An Age Gradient For The Native Shrub Morella Cerifera., Stephen Via May 2012

Impacts Of Rdx Soil Contamination Across An Age Gradient For The Native Shrub Morella Cerifera., Stephen Via

Theses and Dissertations

Understanding the impacts of explosive contamination on vegetation is key to understanding explosives behavior in the environment. I quantified shrub growth responses to 1,3,5-trinitroperhydro-1,35-triazine (RDX) soil contamination across three life stages and I hypothesized that RDX would have the greatest impact on seed germination. Morella cerifera seeds were germinated on soils amended with RDX up to 1500 mg RDX kg-1 dry soil. Juvenile and adult individuals were exposed for 6 weeks to soil amended with RDX up to 750 and 1500 mg RDX kg-1 dry soil, respectively. Morphological responses were quantified for juveniles while physiological measurements were quantified for adults. …

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Expression Of Foreign Genes In The Pseudomonas Bacteriophage Pf3, Krystin Weathers May 2012

Expression Of Foreign Genes In The Pseudomonas Bacteriophage Pf3, Krystin Weathers

Theses and Dissertations

Filamentous bacteriophages were engineered to express foreign genes with the ultimate purpose of displaying transmission control anti-malarial peptides as in phage display. It was hypothesized that expression of foreign genes would be possible using the phage’s promoters. This hypothesis was tested by assuming that promoters for the phage major coat protein (MCP) gene would also promote the expression of any foreign gene inserted downstream of the MCP gene. As proof of principle, the bacteriophages Pf3, Pf1, and M13 were engineered in this way to successfully synthesize Enhanced Green Fluorescent Protein (EGFP). Type 88 phage display on the EGFP recombinant Pf3 …

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Functional And Biochemical Consequences Of Single Nucleotide Polymorphisms In The Human Vesicular Monoamine Transporter 1 Gene (Slc18a1) By Sally Gamal Shukry, B.S., Sally Gamal Shukry May 2012

Functional And Biochemical Consequences Of Single Nucleotide Polymorphisms In The Human Vesicular Monoamine Transporter 1 Gene (Slc18a1) By Sally Gamal Shukry, B.S., Sally Gamal Shukry

Theses and Dissertations

Abstract FUNCTIONAL AND BIOCHEMICAL CONSEQUENCES OF SINGLE NUCLEOTIDE POLYMORPHISMS IN THE HUMAN VESICULAR MONOAMINE TRANSPORTER 1 GENE (SLC18A1) By Sally Gamal Shukry, B.S. A thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology at Virginia Commonwealth University. Virginia Commonwealth University, 2012 Major Advisor: Jennifer K. Stewart Associate Professor and Graduate Director, Department of Biology Single nucleotide polymorphisms (SNP) in the human VMAT1 gene (SLC18A1) have been associated with schizophrenia in three different populations: Han Chinese, Western European and Japanese. Effects of these mutations on transport function of the hVMAT1 protein have not …

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A Multifaceted Approach Identifies Erbb2 And Erbb3 Proteins And Microrna-125b As Key Contributors To Prostate Cancer Progression, Danielle Weaver Apr 2012

A Multifaceted Approach Identifies Erbb2 And Erbb3 Proteins And Microrna-125b As Key Contributors To Prostate Cancer Progression, Danielle Weaver

Theses and Dissertations

Prostate cancer is the most common cancer affecting men today. Therefore, there is a strong need for accurate biomarkers and successful therapeutic treatments. A novel approach combining a computationally built protein-protein interaction network of proven microRNA protein targets with high throughput proteomics identified ErbB2 and ErbB3 as key proteins in prostate cancer. These results coupled with microRNA array screening of an androgen-independent prostate cancer progression model, substantiated by single microRNA analysis, suggested miR125b as a key tumor suppressor contributing to prostate cancer progression. miR125b expression was shown to be substantially increased in the non-tumorigenic P69 cell line compared to its …

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Assessing The Genotoxicity Of Triclosan In Tadpoles Of The American Bullfrog, Lithobates Catesbeianus., David Emery Apr 2012

Assessing The Genotoxicity Of Triclosan In Tadpoles Of The American Bullfrog, Lithobates Catesbeianus., David Emery

Theses and Dissertations

Amphibians are particularly sensitive to environmental degradation and, therefore, serve as effective environmental quality indicators. Research has suggested that amphibian declines are exacerbated by manmade environmental toxicants, especially those found in high concentrations in urban areas. The NIH has pinpointed genotoxicity as a major route of cancer causation, and has since developed stringent testing procedures for potentially hazardous chemicals. One such method, recognized for its simplicity and economy, is the micronucleus assay. A study was conducted assessing the genotoxicity of the widely used antimicrobial agent Triclosan to American Bullfrog tadpoles. Lithobates catesbeianus tadpoles were reared in glass aquaria containing ultra-high …

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Spatial Distribution And Modulation Of Nitric Oxide Synthase In A Hypertensive Rat Model, Andrew Yannaccone Feb 2012

Spatial Distribution And Modulation Of Nitric Oxide Synthase In A Hypertensive Rat Model, Andrew Yannaccone

Theses and Dissertations

There are gaps in the fundamental understanding of the expression of nitric oxide synthases (NOS) in the microvasculature. We examined co-localization of NOS1 (nNOS), NOS2 (iNOS) and NOS3 (eNOS) in the spinotrapezius muscle of young adult male Wistar-Kyoto (WKY) and Spontaneously Hypertensive (SHR) rats according to fiber type using immunohistochemistry and brightfield microscopy. Data regarding fiber distribution, population and morphology data were collected. Alkaline phosphatase staining was used to determine capillary density and average number of capillaries around a fiber. Gel electrophoresis and Western blot techniques were used to compare myosin heavy chain (MHC) protein expression with fiber type population …

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Epigenetic Regulation Of Genes Involved In Vascular Dysfunction In Preeclamptic Women, Ahmad Mousa Jan 2012

Epigenetic Regulation Of Genes Involved In Vascular Dysfunction In Preeclamptic Women, Ahmad Mousa

Theses and Dissertations

DNA methylation is the most recognizable epigenetic mechanism. In general, DNA hypomethylation is associated with increased gene expression whereas DNA hypermethylation is associated with decreased gene expression. To date, little is known about the role of DNA methylation in the pathophysiology of preeclampsia. In this study, we examined the differences in DNA methylation in omental arteries of normal pregnant and preeclamptic women using the high throughput Illumina HumanMethylation27 BeadChip assay. We found 1,685 genes with a significant difference in DNA methylation at a false discovery rate of < 10% with many inflammatory genes having reduced methylation. The thromboxane synthase gene was the most hypomethylated gene in preeclamptic women as compared to normal pregnant women. When we examined the expression of thromboxane synthase in omental arteries of normal pregnant and preeclamptic women we found it to be significantly increased in preeclamptic women. The increased expression was observed in vascular smooth muscle cells, endothelial cells and infiltrating neutrophils. Experimentally induced DNA hypomethylation increased the expression of thromboxane synthase in the neutrophil-like HL-60 cell line, whereas tumor necrosis factor α (TNFα), a neutrophil product, increased its expression in cultured human vascular smooth muscle cells (VSMC). These finding suggest that DNA methylation and release of TNFα by infiltrating neutrophils could contribute to the increased expression of thromboxane synthase in systemic blood vessels of preeclamptic women, contributing to the hypertension and coagulation abnormalities. We also explored the possible contribution of DNA methylation to the altered expression of genes involved in collagen metabolism in preeclampsia. Several matrix metalloproteinase (MMP) genes, including MMP1 and MMP8, were significantly less methylated in preeclamptic women, whereas TIMP and COL genes were either significantly more methylated or had no significant change in their DNA methylation status. Experimentally induced DNA hypomethylation increased the expression of MMP-1, but not TIMP-1 or COL1A1, in cultured VSMCs and increased the expression of MMP-1 and MMP-8 in HL-60 cells. These findings suggest that DNA methylation contributes to the imbalance in genes involved in collagen metabolism in blood vessels of preeclamptic women.

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Optimizing Read Mapping To Reference Genomes To Determine Composition And Species Prevalence In Microbial Communities, John Martin, Sean Sykes, Sarah Young, Karthik Kota, Riva Sanka, Nihar U. Sheth, Joshua Orvis, Erica Sodergren, Zhengyuan Wang, George M. Weinstock, Makedonka Mitreva Jan 2012

Optimizing Read Mapping To Reference Genomes To Determine Composition And Species Prevalence In Microbial Communities, John Martin, Sean Sykes, Sarah Young, Karthik Kota, Riva Sanka, Nihar U. Sheth, Joshua Orvis, Erica Sodergren, Zhengyuan Wang, George M. Weinstock, Makedonka Mitreva

Study of Biological Complexity Publications

The Human Microbiome Project (HMP) aims to characterize the microbial communities of 18 body sites from healthy individuals. To accomplish this, the HMP generated two types of shotgun data: reference shotgun sequences isolated from different anatomical sites on the human body and shotgun metagenomic sequences from the microbial communities of each site. The alignment strategy for characterizing these metagenomic communities using available reference sequence is important to the success of HMP data analysis. Six next-generation aligners were used to align a community of known composition against a database comprising reference organisms known to be present in that community. All aligners …

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Shared Resistance To Aging And Als In Neuromuscular Junctions Of Specific Muscles, Gregorio Valdez, Juan C. Tapia, Jeff W. Lichtman, Michael A. Fox, Joshua R. Sanes Jan 2012

Shared Resistance To Aging And Als In Neuromuscular Junctions Of Specific Muscles, Gregorio Valdez, Juan C. Tapia, Jeff W. Lichtman, Michael A. Fox, Joshua R. Sanes

Anatomy and Neurobiology Publications

Normal aging and neurodegenerative diseases both lead to structural and functional alterations in synapses. Comparison of synapses that are generally similar but respond differently to insults could provide the basis for discovering mechanisms that underlie susceptibility or resistance to damage. Here, we analyzed skeletal neuromuscular junctions (NMJs) in 16 mouse muscles to seek such differences. We find that muscles respond in one of three ways to aging. In some, including most limb and trunk muscles, age-related alterations to NMJs are progressive and extensive during the second postnatal year. NMJs in other muscles, such as extraocular muscles, are strikingly resistant to …

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Optogenetic Stimulation Of The Corticothalamic Pathway Affects Relay Cells And Gabaergic Neurons Differently In The Mouse Visual Thalamus, Chris W. D. Jurgens, Karen A. Bell, A. Rory Mcquiston, William Guido Jan 2012

Optogenetic Stimulation Of The Corticothalamic Pathway Affects Relay Cells And Gabaergic Neurons Differently In The Mouse Visual Thalamus, Chris W. D. Jurgens, Karen A. Bell, A. Rory Mcquiston, William Guido

Anatomy and Neurobiology Publications

The dorsal lateral geniculate nucleus (dLGN) serves as the primary conduit of retinal information to visual cortex. In addition to retinal input, dLGN receives a large feedback projection from layer VI of visual cortex. Such input modulates thalamic signal transmission in different ways that range from gain control to synchronizing network activity in a stimulus-specific manner. However, the mechanisms underlying such modulation have been difficult to study, in part because of the complex circuitry and diverse cell types this pathway innervates. To address this and overcome some of the technical limitations inherent in studying the corticothalamic (CT) pathway, we adopted …

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Prey Responses To Predator Chemical Cues: Disentangling The Importance Of The Number And Biomass Of Prey Consumed, Michael W. Mccoy, Justin C. Touchon, Tobias Landberg, Karen M. Warkentin, James R. Vonesh Jan 2012

Prey Responses To Predator Chemical Cues: Disentangling The Importance Of The Number And Biomass Of Prey Consumed, Michael W. Mccoy, Justin C. Touchon, Tobias Landberg, Karen M. Warkentin, James R. Vonesh

Biology Publications

To effectively balance investment in predator defenses versus other traits, organisms must accurately assess predation risk. Chemical cues caused by predation events are indicators of risk for prey in a wide variety of systems, but the relationship between how prey perceive risk in relation to the amount of prey consumed by predators is poorly understood. While per capita predation rate is often used as the metric of relative risk, studies aimed at quantifying predator-induced defenses commonly control biomass of prey consumed as the metric of risk. However, biomass consumed can change by altering either the number or size of prey …

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Genome-Wide Association Study Heterogeneous Cohort Homogenization Via Subject Weight Knock-Down, Andre X. C. N. Valente, Joseph Zischkau, Joo H. Shin, Yuan Gao, Abhijit Sarkar Jan 2012

Genome-Wide Association Study Heterogeneous Cohort Homogenization Via Subject Weight Knock-Down, Andre X. C. N. Valente, Joseph Zischkau, Joo H. Shin, Yuan Gao, Abhijit Sarkar

Study of Biological Complexity Publications

Population structure can be a source of both false-positive and false-negative findings in a genome-wide association study. This article proposes an approach that helps to reduce the false-positives. It consists of homogenizing the diseased/healthy phenotype ratio across the cohort, by decreasing the statistical weight of selected individuals. After homogenization, the cohort is statistically handled as if originating from a single well-mixed population. The method was applied to homogenize a Parkinson's disease genome-wide association study cohort.

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Opposing Roles Of The Μ-Opioid And Nociceptin/Orphanin Fq Receptors In Oligodendrocyte Development And Myelination, Allison Vestal-Laborde Jan 2012

Opposing Roles Of The Μ-Opioid And Nociceptin/Orphanin Fq Receptors In Oligodendrocyte Development And Myelination, Allison Vestal-Laborde

Theses and Dissertations

While the classical function of myelin is to facilitate saltatory conduction, this membrane and the myelin-making oligodendrocytes (OLGs) are now recognized as regulators of plasticity and remodeling in the central nervous system (CNS). Thus, OLG maturation and myelination are highly vulnerable processes along CNS development. We previously showed that rat brain myelination is altered by perinatal exposure to buprenorphine, an opioid analogue in clinical trials for the treatment of pregnant opioid addicts. We now found that the in vivo effects on myelination could result from direct alteration in the balance between μ-opioid receptor (MOR) and nociceptin/orphanin FQ receptor (NOPR) activities …

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Adam10: A Novel Regulator Of Mast Cell Function And Activation, Travis Faber Jan 2012

Adam10: A Novel Regulator Of Mast Cell Function And Activation, Travis Faber

Theses and Dissertations

In this study we show, to our knowledge, the first description of the role ADAM10 plays on mast cells. ADAM10 is abundantly expressed on mast cells both in vitro and in vivo. Its expression is inhibited by IL-10, a suppressive cytokine. siRNA depletion of ADAM10 on bone marrow-derived mast cells (BMMC) caused decreased IL-6 production following IgE cross-linking and also impaired BMMC stem cell factor (SCF)-induced migration through collagen IV. Mast cells and T helper cells (Th cells) in the peritoneum were reduced in ADAM10 KO mice. In addition, ADAM10 KO BMMC produced significantly less of all cytokines measured following …

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Non-Canonical Roles For Stat1 And Stat2 In Mitochondrial Biogenesis And Fasting Homeostasis., Jennifer Sisler Jan 2012

Non-Canonical Roles For Stat1 And Stat2 In Mitochondrial Biogenesis And Fasting Homeostasis., Jennifer Sisler

Theses and Dissertations

The signal transducer and activator of transcription 1 (STAT1) and 2 (STAT2) are primarily activated by interferons and play a central role in orchestrating responses to a variety of pathogens by activating the transcription of nuclear encoded genes that mediate antiviral, antigrowth and immune surveillance responses. In addition to their nuclear effects, we report that STAT1 and STAT2 inhibit the expression of mitochondrial encoded mRNAs by activating type I interferons (IFNβ) under basal conditions. STAT1-/- livers also exhibit elevated levels of nuclear encoded components of the electron transport chain (ETC). Treatment of wild-type mice with IFNβ inhibits both mitochondrial and …

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Transient Camk-Ii Activation Is Necessary For Left-Right Asymmetry In The Zebrafish Embryo, Ludmila Francescatto Jan 2012

Transient Camk-Ii Activation Is Necessary For Left-Right Asymmetry In The Zebrafish Embryo, Ludmila Francescatto

Theses and Dissertations

Despite external bilateral symmetry, the internal organs of vertebrates are asymmetrically arranged. The development of Left-Right (LR) asymmetry is dependent on the activity of a ciliated organ known as the Kupffer’s vesicle (KV) or the embryonic node, in zebrafish and mouse, respectively. Cilia beating within the KV are essential to generate a counterclockwise flow of fluid, which leads to left-sided Ca2+ elevation. Ca2+ is a crucial morphogenic second messenger during vertebrate development. Ca2+ elevation activates targets, such as CaMK-II, which is also known as the multifunctional Ca2+/calmodulin-dependent protein kinase. Studies have linked CaMK-II to secretion (mediated through synapsin I) and …

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Identifying Sortase A Variants With Higher Catalytic Effeciency, Muna Suliman Jan 2012

Identifying Sortase A Variants With Higher Catalytic Effeciency, Muna Suliman

Theses and Dissertations

In the past two decades, the field of protein engineering has evolved rapidly to include new genetic and chemical techniques to alter protein function. Protein engineering seeks to improve enzyme properties through powerful methods that specifically incorporate novel or improved function in proteins. One such method is protein ligation, which is used to selectively link synthetic and recombinant polypeptides. Due to the limitations of current protein labeling techniques, simple site-specific modification methods remain in high demand. Use of enzyme-based labeling has been the focus of various studies because of its substrate specificity. Sortase-mediated transpeptidation is one approach that has been …

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Role Of Lysophosphatidic Acid In Regulation Of Cancer Cell Metabolism, Abir Mukherjee Jan 2012

Role Of Lysophosphatidic Acid In Regulation Of Cancer Cell Metabolism, Abir Mukherjee

Theses and Dissertations

The simplest phospholipid, lysophosphatidic acid (LPA), is a heat stable component of serum known for its proliferative and migratory activities in cancer cells. Strong evidence suggests that LPA production and expression of its receptors are dysregulated in multiple human malignancies. The mechanism behind LPA-mediated tumor cell growth and oncogenesis remains poorly understood. In this thesis project I used ovarian and other cancer cells as a model system to examine the hypothesis that LPA present in the tumor microenvironment is a pathophysiological determinant of hyperactive de novo lipogenesis and aerobic glycolysis, two hallmarks of cancer cells. We demonstrated that LPA induced …

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The Role Of R7 Regulators Of G Protein Signaling In The Retina, Hoon Shim Jan 2012

The Role Of R7 Regulators Of G Protein Signaling In The Retina, Hoon Shim

Theses and Dissertations

The R7 regulators of G protein signaling (R7 RGS), namely RGS6, RGS7, RGS9 and RGS11, are expressed in the retina along with its binding partner Gβ5. The RGS9-1 isoform is expressed only in retinal photoreceptors and rate-limits the recovery of rod phototransduction by acting as a member of the transducin GAP complex (RGS9-1/Gβ5L/R9AP). The Gβ5L isoform is also only expressed in retinal photoreceptors and acts by stabilizing the GAP complex. The Gβ5S isoform differs from Gβ5L by the absence of exon 1 due to alternative splicing and is expressed in many other retinal cells. Gβ5L is barely detectable in RGS9-/- …

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Crosstalk Between Lysophospatidic Acid (Lpa) And Transforming Growth Factor Beta (Tgfβ) In Breast And Ovarian Cancer Cells, Jinhua Wu Jan 2012

Crosstalk Between Lysophospatidic Acid (Lpa) And Transforming Growth Factor Beta (Tgfβ) In Breast And Ovarian Cancer Cells, Jinhua Wu

Theses and Dissertations

Lysophosphatidic acid (LPA) and transforming growth factor beta (TGFβ) are platelet-derived intercellular mediators of cell proliferation and motility. LPA is a general growth, survival and motility-stimulating factor in mammalian cells. TGFβ prevents proliferation of normal epithelial cells. However, the growth-inhibitory effect of TGFβ is lost or reduced in most malignant cells. Instead, TGFβ promotes migration and invasion of advanced cancer cells. Since LPA and TGFβ are both present in the blood and tumor microenvironments, we were interested in signal integration and functional outcomes in malignant epithelial cells in an LPA and TGFβ co-stimulatory context. In a subset of breast and …

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Species Level Differences In The Ecology Of Two Neotropical Tadpole Species: Responses To Nonlethal Predators And The Roles Of Competition And Resource Use, Zacharia Costa Dec 2011

Species Level Differences In The Ecology Of Two Neotropical Tadpole Species: Responses To Nonlethal Predators And The Roles Of Competition And Resource Use, Zacharia Costa

Theses and Dissertations

Closely related species at the same trophic level are often considered to be ecologically equivalent. However, it is clear that individuals species can have unique functional roles that drive community and ecosystem processes. In this study we examine the growth responses of two Neotropical hylid tadpole species, Agalychnis callidryas and Dendropsophus ebraccatus, to intraspecific and interspecific competition. We also look at density-dependent effects of each on phytoplankton, periphyton and zooplankton, as well as their responses to a caged dragonfly predator through ontogeny. Intraspecific competition affected both species similarly, and their effects on resources were qualitatively similar but quantitatively different. Predators …

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Evaluation Of Brook Trout (Salvelinus Fontinalis) Introductions And Re-Introductions Into Four Virginia Blue Ridge Mountain Streams, Michael Isel Iii Dec 2011

Evaluation Of Brook Trout (Salvelinus Fontinalis) Introductions And Re-Introductions Into Four Virginia Blue Ridge Mountain Streams, Michael Isel Iii

Theses and Dissertations

Approximately 100 brook trout were transplanted into each of four Virginia streams in September 2008. Garth Run and Kinsey Run were re-introductions, and Wildcat Hollow and Sweet Run were new introductions. Single pass electrofishing (EF) surveys were conducted with a backpack electrofisher five times during the study. Selected trout > 70 mm but < 100 mm and all trout > 100 mm received a Biomark® 134.2 kHz passive integrated transponder (PIT) tag to identify individual fish upon recapture. Trout were present in all streams almost three years post introductions. Catches decreased across the first four surveys. Young of year catch rates severely decreased from June 2009 (n = …

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Woody Encroachment Mechanisms Of A Symbiotic N-Fixing Shrub: Ecophysiology, Facilitation, And Resource Use Efficiency, Jaclyn Vick Dec 2011

Woody Encroachment Mechanisms Of A Symbiotic N-Fixing Shrub: Ecophysiology, Facilitation, And Resource Use Efficiency, Jaclyn Vick

Theses and Dissertations

Causes and consequences of woody encroachment into grass dominated systems have been widely studied, however functional mechanisms which promote encroachment are largely unknown. Many expansive woody species are shrubs with rhizobial or actinorhizal N-fixing symbiotic associations. Morella cerifera L. (Myricaceae) is an actinorhizal N-fixing shrub which rapidly expands into grasslands on the barrier islands off the coast of Virginia, USA. The objective of this research was to determine physiological drivers of woody encroachment resulting in increased woody cover of M. cerifera on Southeastern, US barrier islands. Variations in physiology and resource use efficiencies (RUE) of M. cerifera and co-occurring shrubs …

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Factors Controlling Dissolved Organic Carbon Lability And Ecological Fate In The East Branch Swift River, Massachusettes, Hall Eric Dec 2011

Factors Controlling Dissolved Organic Carbon Lability And Ecological Fate In The East Branch Swift River, Massachusettes, Hall Eric

Theses and Dissertations

Fluvial systems have been estimated to transform, transport, or store 2.75 petagrams (Pg) of Organic Carbon (OC) per year. Although approximately 1Pg per year of terrestrial carbon is fluxed to the atmosphere through inland waters, little is known about the factors regulating its eventual ecological fate. 28 day lability incubations were conducted concurrent with the measurement of several environmental parameters including discharge, nutrient concentration, DO13C, and DOC:DON at several sites along Bigelow Brook and the East Branch of the Swift River, Massachusetts. Temporal and spatial variation of DOC, DOC:DON and DO13C were explored. Two distinct DOC consumption rates, short and …

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Characterizing The Phosphorylation State Of Tie2 Using Sh2 Domain Fusion Proteins, Kenneth Yuth Dec 2011

Characterizing The Phosphorylation State Of Tie2 Using Sh2 Domain Fusion Proteins, Kenneth Yuth

Theses and Dissertations

The cardiovascular system develops through two distinct processes in embryogenesis: vasculogenesis, whereby the primary plexus in the heart is formed along with embryonic and extraembryonic vasculature, and angiogenesis, which begins after vasculogenesis and results in the refinement and maturation of the branched vessel system. In pathological angiogenesis, tumors expand by releasing pro-angiogenic factors in response to hypoxic conditions. The Tie receptors, Tie1 and Tie2, are receptor tyrosine kinases that are integral to angiogenic pathways. A family of Angiopoietins, Ang1-4, have been shown to act as ligands for Tie2, of which Ang1 and Ang2 are best characterized. Activation of the receptor …

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Shrubs As Sentinels Of Ordnance Contamination: Using Plant Physiology And Remote Sensing To Detect Tnt In Soils, Kathryn Rubis Nov 2011

Shrubs As Sentinels Of Ordnance Contamination: Using Plant Physiology And Remote Sensing To Detect Tnt In Soils, Kathryn Rubis

Theses and Dissertations

Methods for rapid, safe and effective detection of unmapped buried ordnance are vital to the protection of humans and environmental quality throughout the world. This study aimed to investigate the use of phytosensing and to understand the physiological response of woody plants to 2,4,6-trinitrotoluene (TNT) contamination. Baccharis halimifolia were potted in soils containing various concentrations of TNT and physiological responses were observed over a 9-week experimental period. Measurements included the collection of remotely sensed data, such as hyperspectral reflectance and chlorophyll fluorescence, and traditional plant-level physiological data. In accordance with the hypothesis, low levels of TNT improved physiological response in …

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Computational Modeling And Simulation Study Of Dermal Wound Healing Proliferative Phase, Le Yang Nov 2011

Computational Modeling And Simulation Study Of Dermal Wound Healing Proliferative Phase, Le Yang

Theses and Dissertations

Dermal wound healing proliferative phase is a complicated physiological process in which many growth factors, cell types and matrix components participate. The process must be well coordinated to restore the structural and functional integrity of tissue injured. Many disorders interrupting healing process result in abnormal healing such as chronic wounds or excessive scarring. Mathematical modeling has been used to investigate many aspects of wound healing. Angiogenesis is pertinent for dermal wound healing since the cellular activities involved in tissue repair requires oxygen and nutrients to be delivered to the wound site. By using a hybrid agent-based model, we investigated the …

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