Life Sciences Commons^™

Influence Of Salinity Variations On The Desorption And Lability Of Soil Organic Carbon Associated With Tidal Freshwater Marshes, Lindsey Michelle Koren

Theses and Dissertations

Tidal freshwater marshes (TFMs) are unique ecosystems that bridge the gap between terrestrial and aquatic ecosystems and are important in the sequestration of soil organic carbon. With the ever changing global climate, TFMs are left vulnerable to downstream effects of rising sea level and salt water intrusion due to increases in flooding by saline waters. These changes often act over large spatial and temporal scales resulting in significant impacts to local and regional environments. This multidisciplinary study assessed the amount and lability of desorbed organic carbon in tidal freshwater marsh soils from the Waccamaw River Marsh, South Carolina and Sweet …

Role Of Hepatic Cholesterol Ester Hydrolase (Ceh) In Hydrolyzing Cholesterol Esters (Ce) Delivered Via Sr-Bi (Scavenger Receptor Class B Type I) And Sr-Bii, Saurabh Bajpai

Theses and Dissertations

Reduction of cholesterol ester (CE) from lipid burden lesion-associated macrophage foam cells has been shown to reduce plaque volumes. Hydrolysis of CE to free cholesterol (FC) in macrophages is an essential step for removal of CE from the macrophage and its transport to the liver by high density lipoprotein (HDL) for further metabolism. Since CE must again be hydrolyzed into FC in the liver catalyzing this hydrolysis, it becomes imperative to find the identity of these enzymes. In this study the role of key enzyme in catalyzing the hydrolysis of CE to FC, neutral cholesterol ester hydrolase (CEH) was evaluated. …

Consequences Of Shrub Encroachment: Linking Changes In Canopy Structure To Shifts In The Resource Environment, Steven Brantley

Theses and Dissertations

Shrub expansion in herbaceous ecosystems is emerging as an important ecological response to global change, especially in mesic systems where increases in canopy biomass are greatest. Two consequences of woody encroachment are increases in belowground resources, such as carbon and nitrogen, and reductions in above-ground resources such as light, which affect diversity, community trajectory, and ecosystem function. My objective was to determine how expansion of the nitrogen-fixing shrub Morella cerifera affected the resource environment across a chronosequence of shrub expansion on a Virginia barrier island. I quantified changes in carbon (C) and nitrogen (N) cycling, canopy structure and understory light …

The Presence Of Amphibian Ranavirus In Virginia Warm Water Fish Hatchery Ponds, Elizabeth Nelson

Theses and Dissertations

Amphibian declines have been occurring world wide over the past several decades. Infectious disease and environmental changes have been implicated as the causative agents in these declines. Fish stocking from hatcheries provides a unique opportunity for organisms, including infectious diseases, to travel over long distances. Ranavirus was previously found in two ponds at Harrison Lake National Fish Hatchery in Charles City County, Virginia. Therefore, the primary objective of this study was to determine if ranavirus is present in tadpoles from four warm water fish hatcheries in Virginia. A secondary objective of this study was to determine if there are relationships …

Generation Of Macrophage Chemotactic Factors By Spla2, Andria Chambers

Theses and Dissertations

Removal of apoptotic cells by macrophages is required in order to prevent autoimmune responses. Previous studies have reported that group IIA secretory phospholipase A2 (sPLA2) preferentially binds to apoptotic cells and induces a chemotactic factor which promotes the migration of macrophages to apoptotic cells. Based on these observations, we hypothesized that the pool of sPLA2 trapped on apoptotic cells produces chemoattractant lipids that recruit macrophages to phagocytose the apoptotic cells. To test this hypothesis, Jurkat cells were cultured under normal conditions and induced to undergo early apoptosis through treatment with D,L-threo-dihydrosphingosine. Live and early apoptotic cells were incubated with catalytically …

Factors Affecting Dissolved Oxygen Metabolism In Coastal Plain Streams Of Virginia, Julie Frank

Theses and Dissertations

I investigated seasonal and inter-site variation in factors influencing diel dissolved oxygen (DO) metabolism at four streams in the Virginia Coastal Plain. Data were collected monthly from January to August 2008 to characterize DO metabolism (diel DO amplitude, production, respiration), incident solar radiation (PAR), dissolved nutrients, fine benthic materials (mass, C:N, Chlα) and hydrology (discharge, water transit time, transient storage). Reach-scale metabolism estimates were determined using the one-station diurnal DO technique and transit time and transient storage were determined by conservative tracer additions. Incident solar radiation was the primary determinant of DO metabolism as streams experiencing higher light levels (Herring …

Matrix Metalloproteinase Expression In Models Of Parkinson's Disease, Justin Mcclain

Theses and Dissertations

Parkinson’s disease (PD) is a devastating neurodegenerative disorder characterized by progressive loss of dopaminergic neurons located in the substantia nigra. Accumulating evidence indicates that microglia-driven neuroinflammation contributes significantly to chronic neurodegeneration in PD. The matrix metalloproteinases (MMPs) play an important role in several neuroinflammatory paradigms; however, their relationship to dopaminergic neurodegeneration in PD remains relatively unexplored. To address this, the temporal relationship between MMP-2, MMP-3, MMP-9, and MMP-13 expression and dopaminergic neurodegeneration was compared in the 6-hydroxydopamine (6-OHDA) and lipopolysaccharide (LPS) models of PD. In dopaminergic SH-SY5Y cells, 6-OHDA treatment significantly increased MMP-13 mRNA expression; however, examination of 6-OHDA-lesioned rats …

Coupling Of Autotrophic And Heterotrophic Plankton Food Web Components In The Tidal-Freshwater James River, Usa, Matthew Beckwith

Theses and Dissertations

Empirical studies have shown that algal- and detrital-based food web components are coupled in many pelagic systems as algal carbon enhances bacterioplankton production and growth efficiencies. Such phyto-bacterioplankton coupling impacts carbon flow through plankton food webs, yet the extent of coupling is poorly understood in systems receiving large amounts of allochthonous carbon. To investigate this issue, bacterioplankton abundance (BA) and community composition were compared to chlorophyll a concentrations and phytoplankton production in the tidal-freshwater James River (VA). BA averaged 107 cells mL-1 and was significantly related to chlorophyll a, phytoplankton production, and DOC concentrations. Analysis of DOC quality using fluorescence …

Identification Of Binding Partners Of A Novel P. Falciparum Exported Protein, Monica Zapata

Theses and Dissertations

Plasmodium falciparum is the causative agent of the most severe form of malaria. This parasite drastically modifies its host cell, the erythrocyte, to create a hospitable environment for its growth and reproduction. In order for these modifications to occur, the parasite secretes proteins into the erythrocyte. While the secretion machinery is still unknown, many secreted proteins have been found to have a hydrophobic signal sequence and a novel host-targeting signal downstream of the hydrophobic sequence. A novel P. falciparum protein has been shown to be secreted from the parasitophorous vacuole, yet it lacks both a hydrophobic signal sequence and a …

Novel Mechanisms Regulating Cytokine-Induced Gene Expression In Astrocytes And Glioblastoma Cells, Lauren Bryan

Theses and Dissertations

Chronic inflammation in the brain results in the development of several CNS diseases, including Alzheimer’s and Parkinson’s diseases, multiple sclerosis, and tumors. IL-1, a pro-inflammatory cytokine released by activated microglia and astrocytes, instigates the expression of factors promoting the progression of these CNS disorders, including cytokines, chemokines, and components of matrix remodeling systems, such as the plasminogen activator system. IL-1 also increases the mRNA expression and activity of SphK, the enzyme that phosphorylates Sph to form S1P, a bio-active sphingolipid. This thesis demonstrates that IL-1 and S1P enhance the mRNA and protein expression of PAI-1 and uPAR, two key components …

Molecular Mechanisms For Regulation Of Gene Expression By Lysophosphatidic Acid In Ovarian Carcinoma Cells, Regina Oyesanya

Theses and Dissertations

Lysophosphatidic acid (LPA) is a potent bioactive phospholipid mediator that functions through multiple G protein couple receptors (GPCRs). LPA is elevated in ascites of ovarian cancer patients and is involved in growth, survival and metastasis of ovarian cancer cells. Gene promoter analyses revealed that some LPA-target genes share similar sets of binding sites for prominent transcription factors posing the possibility of a general mechanism for activation of their expression by LPA. Detailed investigation of the mechanisms of regulation of cyclooxygenase 2 (Cox-2), a paradigm of LPA-regulated genes, showed that LPA robustly upregulated the expression of Cox-2 in ovarian cancer cells …

The Role Of Mitogen-Activated Protein Kinases In The Regulation Of Plant Development, Erica Satterfield

Theses and Dissertations

Mitogen-activated protein kinases are part of an evolutionarily conserved protein phosphorylation cascade which serves essential regulatory functions in eukaryotic organisms. Although the role of MAPKs in the regulation of a plant’s response to environmental stress and plant defense has been well established, very little is known about their role in the regulation of plant developmental processes. In order to examine the role of MAPKs in plant growth and development, a strong mammalian MAPK phosphatase (MKP-1), which is known to inactivate MAPKs in plants, was introduced into tobacco plants. In tobacco plants, MKP-1 overexpression altered plant responses to the phytohormones, ethylene …

Role Of Rock And Pkc In Regulation Of Contraction Of Permeabilized Femoral Arterial Smooth Muscle, Brendan Browne

Theses and Dissertations

KCl is traditionally used as a stimulus to examine the role of increases in cytosolic Ca2+ on the regulation of smooth muscle contraction. KCl bypasses GPCR activation, thereby avoiding activation of additional cell signaling systems, such as phospholipase C and PKC that are inherent to Gaq and Ga12/13 stimulation. GPCR activation causes Ca2+ sensitization (greater force for a given increase in Ca2+) by a ROCK- and PKC-dependent inhibition of myosin light chain (MLC) phosphatase. Recent studies have demonstrated that KCl can also produce Ca2+ sensitization, implying that Ca2+ itself may induce Ca2+ sensitization. To test the hypothesis that Ca2+ can …

A Robust Approach To Identifying Tissue-Specific Gene Expression Regulatory Variants Using Personalized Human Induced Pluripotent Stem Cells, Je-Hyuk Lee, In-Hyun Park, Yuan Gao, Jin B. Li, Zhe Li, George Q. Daley, Kun Zhang, George M. Church

Study of Biological Complexity Publications

Normal variation in gene expression due to regulatory polymorphisms is often masked by biological and experimental noise. In addition, some regulatory polymorphisms may become apparent only in specific tissues. We derived human induced pluripotent stem (iPS) cells from adult skin primary fibroblasts and attempted to detect tissue-specific cis-regulatory variants using in vitro cell differentiation. We used padlock probes and high-throughput sequencing for digital RNA allelotyping and measured allele-specific gene expression in primary fibroblasts, lymphoblastoid cells, iPS cells, and their differentiated derivatives. We show that allele-specific expression is both cell type and genotype-dependent, but the majority of detectable allele-specific expression …

Life-Centered Ethics And The Human Future In Space, Michael Noah Mautner

Chemistry Publications

In the future, human destiny may depend on our ethics. In particular, biotechnology and expansion in space can transform life, raising profound questions. Guidance may be found in Life-centered ethics, as biotic ethics that value the basic patterns of organic gene/protein life, and as panbiotic ethics that always seek to expand life. These life-centered principles can be based on scientific insights into the unique place of life in nature, and the biological unity of all life. Belonging to life then implies a human purpose: to safeguard and propagate life. Expansion in space will advance this purpose but will also raise …

Invertebrate Colonization And Plant Architecture: The Influence Of Two Non-Native Milfoil Species, Elizabeth W. Rielly

Theses and Dissertations

The purpose of this study was to determine if the complexity and surface area of a macrophyte’s

structure has an influence on invertebrate colonization, and to determine the influence of two non-native species on invertebrate colonization. Three plant architectures were compared. Floating leaved plants were represented by the following species: Nuphar lutea, Nymphaea odorata, and Brasenia schreberi. Moderately dissected leaved plants were represented by Potamogeton natans, and highly dissected leaved plants were represented by two non-native species, Myriophyllum spicatum and Myriophyllum heterophyllum. The number of invertebrates/g dry biomass and the number of individuals/m², diversity, evenness, and richness were calculated for …

Identification And Characterization Of Prevotella Intermedia 17 Toll-Like Receptor 2 Ligands, Jamie Feng-Hsia Yuan

Theses and Dissertations

Periodontal disease is one of the most prevalent human diseases affecting millions of individuals. Bacteria are the trigger of the host response that then results in initiation and progression of periodontal disease. The interactions between the host and the bacteria, although very complex and intricate, are not well understood. Species of gram-negative anaerobic bacteria implicated in the development of periodontal disease include Porphyromonas gingivalis and Prevotella intermedia. The goal of our study was to identify P. intermedia surface proteins interacting with TLR2 receptor. Using Cy5-labeled surface proteins we identified multiple proteins using our capture assay. The interaction of three …

Spatial And Temporal Variability Of Macroinvertyebrate Communities In Vernal Pools On The Coastal Plain Of Virginia, Shrijeeta Ganguly

Theses and Dissertations

Vernal pools are often defined as seasonal pools that typically are inundated beginning in the winter and then drying out completely in summer. Though evidence of spatial and temporal variability in the macroinvertebrate communities of vernal pools has been found in previous studies, it has not been studied extensively. The primary objective of this study was to determine the extent of variability in the macroinvertebrate communities within vernal pools closely situated in a forested landscape. An effort was made to explain this variability with respect to certain physiochemical environmental variables of the pools. Significant variability was observed in the macroinvertebrate …

Identification Of Camk-Ii Protein Targets In Tissue Culture And Zebrafish Embryos Using Tandem Mass Spectrometry, Alexandra Myers

Theses and Dissertations

Calcium (Ca2+)/calmodulin-dependent kinase 2 (CaMK-II) is one member of a family of Ca2+/calmodulin-dependent protein kinases that responds to intracellular Ca2+ signals (Hudmon, A. and H. Schulman (2002)). CaMK-II is a multifunctional regulator of transcription, cell cycle progression, cell motility and neuronal development. (Wang, C., et al. (2008), Easley, C. A. IV, et al. (2008), Osterhoff, M., et al. (2003), Faison, M. O., et al. (2002)). Recently, CaMK-II has been shown to be important in the early development of vertebrates. In developing zebrafish, disruption of CaMK-II expression has been shown to induce phenotypes similar to those documented in several human diseases. …

Effects Of Metal Protoporphyrins On Burn Wound Conversion, Katie Braun

Theses and Dissertations

A murine model was utilized to test the influence of heavy metal protoporphyrins on burn conversion, heme oxygenase – 1 (HO-1) expression, and inflammation. Heavy metal protoporphyrins, such as cobalt protoporphyrin (Co PP) and tin protoporphyrin (Sn PP), were used to influence the heme oxygenase activity. The effects of these heavy metal protoporphyrins on burn wound conversion were examined using a burn comb model in rats. In addition to assessing the extent of conversion, HO-1 expression and parameters of inflammation were also examined in the area of injury (interspace region) subject to conversion. These studies demonstrate proof in principal that …

Effects Of Light Exposure On The Release Of Oxygen From Hemoglobin In A Red Blood Cell Suspension, Tanikka Toler

Theses and Dissertations

The main function of the cardiovascular system is to deliver a sufficient quantity of oxygenated blood to the tissues, cells, and organs of the body in order to provide the cells with essential nutrients for metabolism and for the removal of waste products. All cells require and utilize oxygen. Oxygen is transported to various cells and tissues via red blood cells flowing through the microcirculation of an organism. Measurement of oxygen transport in the microcirculation has shown that about ten times more oxygen appears to leave the blood of arterioles than can be accounted for by diffusion. One possibility to …

Molecular Mechanisms Involved In Oligodendrocyte Development, Rochelle Coelho

Theses and Dissertations

Multiple sclerosis (MS) is a chronic disease of the central nervous system (CNS) characterized by demyelination and loss of oligodendrocytes (OLGs), the CNS myelin-producing cells. Thus, understanding the mechanisms that control OLG development can provide valuable knowledge regarding remyelination therapies for MS. This disease is thought to result from an autoimmune attack towards myelin. FTY720, an immunomodulator under evaluation for MS treatment is a sphingosine-1-phosphate (S1P) analog. We found before that S1P plays a crucial role in the NT-3-mediated survival of OLGs, an observation that led us to investigate whether FTY720 could have any effect on these cells. Our studies …

Co-Administration Of Sildenafil Potentiates Doxorubicin-Induced Apoptosis In Prostate Cancer: The Role Of Nf-Kappab, Sarah Hassanieh

Theses and Dissertations

Our recent studies have shown that that erectile dysfunction (ED) drugs including Sildenafil (Viagra), Vardenafil (Levitra) and Tadalafil (Cialis) enhance killing of several types of cancer cells by anticancer drug, Doxorubicin (DOX). We observed increased cell death by apoptosis in response to the combined treatment with ED drugs and DOX. However, the mechanism of such enhancement of cell death by combined treatment of ED drugs and DOX is not fully understood. Nuclear factor-κB (NF-κB) is an oxidant-sensitive transcription factor that plays a critical role in the immediate-early activation of a multitude of genes that have been documented to play critical …

Regulation Of Mdm2 Mediated Nfκb2 Pathway In Human Lung Cancer, Lathika Mohanraj

Theses and Dissertations

Overexpression of oncoprotein MDM2 and mutations of tumor suppressor p53 are frequently observed in human cancers. The NFκB pathway is one of the deregulated pathways in oncogenesis. The overall goal of the project was to study the regulation of NFκB pathway by MDM2 in lung cancer. Our first effort was to determine the frequency of MDM2 overexpression in human lung tumor samples and to identify co-occurring abnormal gene expression by studying the levels of MDM2 and members of NFκB pathway with respect to p53 status. Higher than normal levels of MDM2 were found in approximately 30% of the cancer samples …

Does Light Control Algal Abundance In Large River Systems?, Amy Macdonald

Theses and Dissertations

A limited amount of research has been done to investigate the factors influencing algal abundance in large river systems. This study examines light as the primary factor that controls algal abundance in the Upper Mississippi, Missouri and Ohio Rivers. Data were collected for 2004 in conjunction with the Environmental Monitoring Assessment Program- Great River Ecosystems EMAP-GRE project using EPA approved methods. Chlorophyll a concentrations were 34.6 µg•L-1 in the Upper Mississippi, 19.8 µg•L-1 in Missouri River and 9 µg•L-1 in the Ohio River for 2004. Chlorophyll a concentrations were significantly different among the three rivers (p<0.0001) but not between years. Inter-river variation could be loosely correlated with light availability: mean Average Irradiance Dosages, which consider factors that affect light climate (depth, transparency, velocity, surface irradiance), by river corresponded with mean chlorophyll a levels by river. Intra-river variation seemed to be due to both the influence of light and nutrients.

Crosstalk Between Mdm2 And Akt Signaling Pathway In Oncogenesis., Mahesh Ramamoorthy

Theses and Dissertations

MDM2, the human homologue of the Mouse Double Minute 2 gene product, has been shown to be over-expressed in many cancers and to induce tumorigenesis. The role of MDM2 in oncogenesis was thought to be p53 dependent. However recent years have shown MDM2 to be a key player in a complex network of interactions that affect cell cycle, apoptosis, and tumorigenesis in a p53 independent manner. Here we report a novel p53 independent role for the multidimensional protein MDM2; its ability to induce phosphorylation of Akt at serine 473 residue. Transient and stable over-expression of MDM2 in cultured cell lines …

Ceramide Kinase And Ceramide-1-Phosphate, Dayanjan Wijesinghe

Theses and Dissertations

Ceramide-1-phosphate (C1P) is a bioactive lipid that has been implicated in many biological processes. Our laboratory has conclusively demonstrated its role in inflammation via activation of cPLA2α. The only known enzyme to date responsible for direct synthesis of C1P is ceramide kinase. Very little was known about this enzyme in terms of its enzyme kinetics and substrate specificity. As CERK is an enzyme that acts on membrane lipids, its kinetics cannot be studied using standard bulk dilutions methods. Thus we developed a surface dilution approach using Triton X 100 mixed micelles for studying the kinetics of CERK. We discovered that …

Avian Dispersal Of The Actinomycete Frankia Across A Barrier Island Landscape, Spencer Bissett

Theses and Dissertations

In the nutrient-poor soils characteristic of coastal environments, symbiotic association with the nitrogen-fixing root endosymbiont Frankia is essential to establishment and survival of the woody shrub Morella cerifera. Nutrient deficiency quickly becomes severe unless seedlings are infected by Frankia soon after germination. However, the means of arrival of Frankia prior to shrub establishment has not been determined. Using sterilized lab-grown M. cerifera seedlings and fecal samples collected from passerine birds on the Eastern Shore of Virginia, viability of avian dispersal of the bacteria was tested. Although passerine fecal samples did produce nodules on some sterilized M. cerifera seedlings, these experimental …

Application Of Shortest-Path Network Analysis To Identify Genes That Modulate Longevity In Saccharomyces Cerevisiae, Jr Managbanag

Theses and Dissertations

Shortest-path network analysis was employed to identify novel genes that modulate longevity in the baker’s yeast Saccharomyces cerevisiae. Based upon a set of previously reported genes associated with increased life span, a shortest path network algorithm was applied to a pre-existing protein-protein interaction dataset in order to construct a shortest-path longevity network. To validate this network, the replicative aging potential of 88 single gene deletion strains corresponding to predicted components of the shortest path longevity network was determined. The 88 single-gene deletion strains identified by a network approach are significantly enriched for mutation conferring both increased and decreased replicative life …

The Role Of Microrna-155 And Microrna-146a As Putative Oncomirs In The Tumor Progression Of Prostate Cancer, Jennifer Hoyt

Theses and Dissertations

Prostate cancer is the most common cancer occurring in males. The identification of novel microRNAs (miRs) that contribute to tumor progression represents prospective treatment targets. miRs are small non-coding RNAs important in gene regulation with specific tissue expression patterns. Each miR is thought to affect the expression of hundreds of different RNA targets. Two putative oncomiRs, miR-155 and miR-146a, were shown to be differentially expressed in the human derived, prostate cell sublines M12 and F6. Quantification of endogenous miR expression showed high levels in the metastatic M12 cell line versus low in its weakly tumorigenic F6 variant. The restoration of …