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Impact Of Second Messenger Modulation On Activity-Dependent And Basal Properties Of Excitatory Synapses, Chun Yun Chang

All Theses and Dissertations (ETDs)

Cognitive processing in the central nervous system relies on accurate information propagation; neurotransmission is the fundamental mechanism underlying network information flow. Because network information is coded by the timing and the strength of neuronal activity, synaptic properties that translate neuronal activity into synaptic output profoundly determine the precision of information transfer. Synaptic properties are in turn shaped by changes in network activity to ensure appropriate synaptic output. Activity-dependent adjustment of synaptic properties is often initiated by second messenger signals. Understanding how second messengers sculpt synaptic properties and produce changes in synaptic output is key for elucidating the interplay between network …

Functional Genomic Examinations Of Interactions Between Common Members Of The Human Gut Microbiota, Michael Mahowald

All Theses and Dissertations (ETDs)

The adult human gut microbiota consists of hundreds to thousands of bacterial species, the majority belonging to the Bacteroidetes and the Firmicutes. Differences in the balance between these phyla has been linked to obesity in mice and humans. However, little is known about their interactions in vivo. I have used comparative and functional genomics, proteomics and biochemical assays to identify the ways they marshal their genomic resources to adapt to life together in the distal gut. I first annotated the complete genome sequences of two human gut Bacteroidetes (Bacteroides vulgatus and Parabacteroides distasonis) and two Firmicutes (Eubacterium rectale and E. …

Regulation Of Peripheral Nerve Regeneration By The Mtor Pathway, Namiko Abe

All Theses and Dissertations (ETDs)

While neurons in the central nervous system: CNS) have limited capacity for regrowth after damage, neurons in the peripheral nervous system: PNS) have a robust ability to regenerate their axons following injury. Successful regeneration depends upon both extrinsic cues in the environment and the activation of intrinsic mechanisms to promote regrowth. A number of inhibitory molecules in the CNS environment that prevent axonal regrowth have been identified, but less is known regarding the signaling mechanisms that regulate regenerative ability in PNS neurons. Here, we explored multiple components of injury signaling in the PNS, including the retrograde transport of local axonal …

The Impact Of Interferon Regulatory Factor 3 On The Immune Response To Herpes Simplex Virus Type I Infection, Vineet Menachery

All Theses and Dissertations (ETDs)

The type I interferon: IFN) cascade is critical in control of herpes simplex virus type I: HSV-1) infection and relies on specific recognition molecules to rapidly signal viral infection via interferon regulatory factor-3: IRF-3) -dependent pathways. The absence of these recognition molecules or the loss of IRF-3 would be predicted to render early recognition pathways inoperative and thus impact viral infection. However, previous results had produced contradictory results in terms of the role of IRF-3 during HSV-1 infection. In this study, infected IRF-3-/- immune cells were found to support increased HSV-1 replication compared to control cells. In addition, IRF-3 deficient …

Mechanisms Of Copper-Dependent Notochord Formation In Zebrafish, John Gansner

All Theses and Dissertations (ETDs)

The interplay of genes and nutrition during early development profoundly impacts fetal outcome. Copper is an essential nutrient required for the redox activity of many enzymes, and recent work in our laboratory has elucidated the phenotype of copper deficiency in zebrafish, which includes a strikingly distorted notochord. The studies described here establish the specific genetic etiology of this distortion and reveal a number of gene-gene and gene-nutrient interactions critical to notochord morphogenesis. We first demonstrate that the notochord distortion observed in copper-deficient zebrafish results from lysyl oxidase cuproenzyme inhibition. Four lysyl oxidase family members are expressed throughout the developing zebrafish …

A Multi-Scale Evaluation Of Eastern Hognose Snake (Heterodon Platirhinos) Habitat Selection At The Northern Extent Of Its Range, Celine Goulet

Master's Theses and Capstones

A complex interaction of biotic and abiotic variables structure landscapes into a hierarchal assemblage of habitats. Species respond to this environmental hierarchy by selecting habitat based upon a set of ecological variables occurring across a range of organizational levels. However, as the criteria for selection may be scale-dependent, it is vital to quantify the influence these variables have on species distribution at each spatial scale. Two years of telemetry data from 17 individuals were used to examine the multi-scale selection process in the northern population of Heterodon platirhinos on the New Boston Air Force Station in New Boston, New Hampshire. …

Aspects Of The Reproduction Of An Invasive Crab, Hemigrapsus Sanguineus, In Northern And Southern New England, Emily F. Gamelin

Master's Theses and Capstones

Populations of the invasive shore crab, Hemigrapsus sanguineus , were studied in northern and southern New England to determine if crabs differ in reproductive behavior or characteristics between these regions. Additionally, effects of temperature on reproductive activity were quantified through laboratory experimentation.

Number of broods per season increased with temperature, but the seasonal total was limited to three broods in laboratory experiments. Broods experienced limited success at the lowest temperature, 10°C. The reproductive season was longer at lower latitudes, and females at this site had smaller average ovigerous size. Patterns of ovigery varied between the regions, suggesting the production of …

Investigating Pheromone Variability In A Terrestrial Woodland Salamander, Adam James Chowinard

Master's Theses and Capstones

The communication system of Plethodontid salamanders relies heavily upon chemical signaling. Pheromone molecules convey a tremendous amount of information to conspecifics, and facilitate a wide variety of the essential social functions of these animals. Much of the information contained within the pheromone mixture is variable from one individual to the next, such as the ability to recognize specific individuals, the size of the sender, and the relative "quality' of the signal. In order for variable information to be conveyed through chemical signals, the corresponding variability must be contained within the pheromone mixture itself. This variability may exist as a gradient …

The Influence Of Stocking Density And Acoustic Conditioning On The Behavior And Growth Of Atlantic Cod, Gadus Morhua, Daniel Ward

Master's Theses and Capstones

The goal of experiment one (Chapter One) was to determine if stocking density had an influence of the swimming behavior and spatial distribution of adult cod that were being raised in an aquaculture cage at the University of New Hampshire's Coastal Marine Laboratory. Acoustic telemetry and underwater video were used to quantify the behavior and distribution of cod that were stocked at four densities (5, 10, 25 and 45 kg/m³). At the lowest density (5 kg/m³) cod remained deep in the cage and spent 64.3 +/- 0.8% of their time below 1.80m (of a 2.70m cage). This contrasts to the …

Isotopic Analysis Of Arctic Ground Squirrel Tissues And Potential Food Sources, Julee Shamhart

Master's Theses and Capstones

Given limited knowledge of the food sources of Arctic ground squirrels, an important arctic prey species, it is difficult to predict the implications of changes in food source availability that could result from climate change. I hypothesized that Arctic ground squirrels at two colonies, Atigun and Toolik, would have similar feeding habits and mushrooms would contribute to their diet The Arctic ground squirrels at Toolik had significantly higher del15N (3.7 per mill difference) and del13C values (1.3 per mill difference) than those at Atigun. Mixing models indicated that the signatures observed in the Atigun hair could result from a combination …

Bryostatins: Biological Context And Biotechnological Prospects, Amaro E. Trindade-Silva, Grace E. Lim-Fong, Koty H. Sharp

Arts & Sciences Faculty Publications

Coral animals harbor diverse microorganisms in their tissues, including archaea, bacteria, viruses, and Bryostatins are a family of protein kinase C modulators that have potential applications in biomedicine. Found in miniscule quantities in a small marine invertebrate, lack of supply has hampered their development. In recent years, bryostatins have been shown to have potent bioactivity in the central nervous system, an uncultivated marine bacterial symbiont has been shown to be the likely natural source of the bryostatins, the bryostatin biosynthetic genes have been identified and characterized, and bryostatin analogues with promising biological activity have been developed and tested. Challenges in …

Role Of Protein Kinase Ck2 And Phosphatase Pp2a In Notch-Mediated Lateral Inhibition, Anasua Bose

Graduate Theses, Dissertations, and Problem Reports (ETD)

The Notch signaling pathway is highly conserved in vertebrates and invertebrates and regulates binary cell fate specifications in diverse developmental contexts. In a process termed lateral inhibition, Notch signaling restricts a particular cell fate to a single cell from a group of multi-potential cells. This mechanism ensures precision in cell fate assignations, which are vital for histogenesis and organogenesis. Studies during Drosophila neurogenesis, specifically development of the compound eye and the mechanosensory bristles, have provided the most detailed insights into the underlying mechanisms. During this process, Notch signaling results in the selection of single R8 photoreceptors or bristle sensory organ …

The Hematopoietic Compartment Regulates Osteoblast Differentiation And Apoptosis During Cytokine Treatment, Matthew Christopher

All Theses and Dissertations (ETDs)

Adult hematopoiesis normally occurs in bone marrow, where hematopoietic stem cells: HSC) reside within a specialized microenvironment. At steady state, hematopoiesis state is regulated such that immature hematopoietic stem and progenitor cells: HSPC) are restricted to the bone marrow and are rarely observed in peripheral blood. Under certain circumstances, however, this regulation is loosened and significant numbers of HSPC are released to the circulation, a process termed "mobilization." Mobilization can be induced pharmacologically by a wide range of agents. Of these, the best characterized and most widely used mobilizing agent is Granulocyte-colony stimulating factor: G-CSF). G-CSF is widely used clinically …

Ionic Mechanisms Of Action Potential Rate Dependence, Conduction And Block In Normal Epicardium And In Remodeled Epicardium Post-Infarction, Keith Decker

All Theses and Dissertations (ETDs)

In this work, detailed computational models are used to study the electrophysiology of normal epicardium and the arrhythmogenic effects of epicardial cell remodeling post-infarction. The canine epicardial myocyte model described here reproduces a wide range of experimentally observed rate dependent phenomena in cell and tissue. Model behavior depends on updated formulations for the 4-AP sensitive transient outward current: Ito1), the slow component of the delayed rectifier potassium current: IKs), the L-type Ca2+ channel: ICa,L) and the sodium-potassium pump: INaK) fit to data from canine ventricular myocytes. The model shows that Ito1 plays a limited role in potentiating peak ICa,L and …

Use-Dependent Plasticity Regulates Sleep Need In Drosophila Melanogaster, Jeffrey Donlea

All Theses and Dissertations (ETDs)

Although the necessary functions of sleep have not been identified, sleep has been shown to play an important role in the consolidation of memories. Recent studies have shown that, in addition to playing a strong role in sleep regulation, the circadian clock also influences processes associated with learning and memory. Thus, the neural circuits that control circadian rhythms are uniquely positioned to play an important role in coordinating interactions between sleep and memory. Drosophila melanogaster exhibit increased sleep following several days of social experience and require sleep to consolidate long-term memories: LTM) after Courtship Conditioning, an associative memory assay. We …

Local And Systemic Consequences Of Reducing Notch Signaling In Skin Keratinocytes, Shadmehr Demehri

All Theses and Dissertations (ETDs)

Notch is a transmembrane receptor that mediates short-range signaling between neighboring cells. Notch signaling has been implicated in various cellular and developmental processes essential in the life of metazoans. Specifically, Notch signaling plays a critical role in mammalian skin. Removal of Notch alleles in skin keratinocytes has been associated with an array of phenotypes with varying severity based on the identity and number of remaining Notch receptors. Phenotypes include carcinogenesis: in the case of Notch1 loss), transformation of hair follicles to epidermal cysts and neonatal lethality, the latter seen in the absence of all Notch signaling. Although these phenotypes were …

Characterization Of Streptolysin O As The Translocator For The Cytolysin-Mediated Translocation Process In Streptococcus Pyogenes, N'Goundo Magassa

All Theses and Dissertations (ETDs)

Secretion of toxins into host cells is an important component of microbial pathogenesis. In order to gain access to the host cell cytosol, toxins must cross the plasma membrane, traverse the membrane of endocytic vesicles, or cross the membrane of organelles. The process cytolysin-mediated translocation: CMT) in Streptococcus pyogenes uses the pore-forming protein streptolysin O: SLO) to translocate the S. pyogenes NAD+-glycohydrolase: SPN) effector into the cytosol of eukaryotic host cells. Although, the fundamentals of this protein translocation process are established the details of the mechanism remain elusive. The current studies illustrate that the translocation process is more complex than …

The Mechanisms And Roles Of Neural Feedback Loops For Visual Processing, Debajit Saha

All Theses and Dissertations (ETDs)

Feedback pathways are widely present in various sensory systems transmitting time-delayed and partly-processed information from higher to lower visual centers. Although feedback loops are abundant in visual systems, investigations focusing on the mechanisms and roles of feedback in terms of micro-circuitry and system dynamics have been largely ignored. Here, we investigate the cellular, synaptic and circuit level properties of a cholinergic isthmic neuron: Ipc) to understand the role of isthmotectal feedback loop in visual processing of red-ear turtles, Trachemys scripta elegans. Turtle isthmotectal complex contains two distinct nuclei, Ipc and Imc, which interact exclusively with the optic tectum, but are …

Seed Dispersal By Pulp Consumers, Not ‘‘Legitimate’’ Seed Dispersers, Increases Guettarda Viburnoides Population Growth, Andrea P. Loayza, Tiffany M. Knight

Biology Faculty Research

We examined the effect of seed dispersal by Purplish Jays (Cyanocorax cyanomelas; pulp consumers) and the Chestnut-eared Araçari (Pteroglossus castanotis; "legitimate" seed dispersers) on population growth of the small tree Guettarda viburnoides (Rubiaceae) in northeastern Bolivian savannas. Because each bird species differs with respect to feeding and post-feeding behavior, we hypothesized that seed dispersal by each species will contribute differently to the rate of increase of G. viburnoides, but that seed dispersal by either species will increase population growth when compared to a scenario with no seed dispersal. To examine the effects of individual dispersers on the future population size …

Impacts Of Suburbanization On Food Web Stoichiometry Of Detritus-Based Streams, Nathaniel Burr Morse

Master's Theses and Capstones

Higher non-point source nutrient inputs are one of many impacts associated with the "urban stream syndrome". Research on how non-point source pollution affects the stoichiometry of urban stream food webs has received little attention, however. This study quantified food web stoichiometry in nine headwater, detritus-based streams draining forested or suburban watersheds in northeastern, coastal Massachusetts.

While this study suggests that suburbanization can affect in-stream nutrient recycling by consumers, research that quantifies changes to biomass of different in-stream compartments is needed to calculate the extent of such impacts on suburban stream ecosystems.

Population Ecology And Reproductive Biology Of The Diamondback Watersnake, Nerodia Rhombifer (Serpentes: Colubridae), In Southernmost Texas, Ruben D. Zamora

Theses and Dissertations - UTB/UTPA

Nerodia rhombifer is a polytypic, semi-aquatic snake with a broad geographical distribution ranging from the American Midwest southward to Chiapas, Mexico. Although relatively abundant throughout much of its range, few ecological studies of the species have been conducted. This study provides basic population ecology information in a subtropical habitat. Population data were obtained in a mark-recapture study at Santa Ana National Wildlife Refuge, Hidalgo County, Texas, from August 1995 to December 1998. Specimens taken elsewhere in Hidalgo County provided information on the reproductive biology. This study provides the first absolute density estimates from anywhere within the species’ range. Quantitative information …

An Intertidal Sea Star Adjusts Thermal Inertia To Avoid Extreme Body Temperatures, Sylvain Pincebourde, Eric Sanford, Brian Helmuth

Faculty Publications

The body temperature of ectotherms is influenced by the interaction of abiotic conditions, morphology, and behavior. Although organisms living in different thermal habitats may exhibit morphological plasticity or move from unfavorable locations, there are few examples of animals adjusting their thermal properties in response to short-term changes in local conditions. Here, we show that the intertidal sea star Pisaster ochraceus modulates its thermal inertia in response to prior thermal exposure. After exposure to high body temperature at low tide, sea stars increase the amount of colder than-air fluid in their coelomic cavity when submerged during high tide, resulting in a …

Lifelines Fall 2009, Southern Adventist University

Lifelines - Biology Department Newsletter

The Fall 2009 issue of Lifelines includes articles on Southern's Ancient DNA Project, an alumni feature, student research, and news from the Pre-Dent Club.

Uropathogenic E. Coli Employ A Conserved Intracellular Infection Pathway That Can Be Inhibited By Novel Anti-Virulence Therapeutics, Corinne Cusumano

All Theses and Dissertations (ETDs)

Urinary tract infections: UTIs) affect 13 million women annually in the United States and are predominately caused by uropathogenic Escherichia coli: UPEC). In a murine cystitis model, UPEC utilize a multistep pathogenic pathway in which they invade and form intracellular bacterial communities: IBCs) within bladder facet cells. Type 1 pili expressing the adhesin, FimH, are necessary for UPEC binding and invasion of urothelial cells and formation of IBCs. UPEC ultimately disperse from the IBC, many with filamentous morphology, and infect other host urothelial cells. Using a panel of UPEC clinical isolates, this work evaluates the conservation of the IBC pathway …

Dissecting The Molecular Mechanisms Underlying Synpase Development And Neuronal Functions In Caenorhabditis Elegans, Shuo Luo

All Theses and Dissertations (ETDs)

The development and function of the nervous system is under delicate regulation of diverse tissue-derived signals in multi-cellular organisms. In Dr. Nonet's lab, I am using the model organism Caenorhabditis elegans to ask two basic questions: 1) How do different tissues in an organism coordinate to regulate neural functions and behaviors? 2) What controls the development of synapse, the basic unit of the nervous system? These questions divide my dissertation into three parts, with the first two parts related to the first question and the third part to the second question. In the first part of this dissertation, I present …

A New Quantitative Method For The Taxonomic Identification Of Tetrapods, Stephanie Kuster

All Theses and Dissertations (ETDs)

The rarity of good fossil samples throughout geologic time frequently makes fossil identification difficult. This dissertation presents a new, multivariate, statistically validated method to identify tetrapods based on quantification of the shapes of microstructural features in cortical bone of the postcranial skeleton. The ultimate goal is to reduce the reliance on rare, near-complete fossil skeletons. The method is validated on a set of 15,745 mammalian microstructural features from eleven diverse species. An additional set of 21,122 microstructural features from one species serve to examine microstructural variation within a single skeleton. Microstructural measurements were made on thin-sections using optical microscopy. Initial …

Growth Factor Delivery From Fibrin Matrics Containing Affinity-Based Delivery Systems To Treat Peripheral Nerve Injury, Matthew Wood

All Theses and Dissertations (ETDs)

This thesis work sought to develop a biomaterial to further the understanding of affinity-based delivery and to serve as a potential treatment for peripheral nerve injury. The use of an affinity-based delivery system: ABDS) with growth factors in a nerve guidance conduit: NGC) was hypothesized to promote nerve regeneration and functional recovery following a critical nerve defect. Evaluation of affinity-based delivery using peptides with varying binding affinity for heparin determined that peptide binding affinity for heparin affected the release rate and biological activity of nerve growth factor: NGF) in vitro. The ABDS presented biologically active NGF, which promoted neurite extension …

An Examination Of The Correlation Between Shoot Apical Meristem Size And Leaf Heterophylly In Pisum Sativum, Cynthia Mary Halfman

Undergraduate Honors Thesis Collection

This study is a quantitative examination of the ramifications of leaf development as influenced by the size of the shoot apical meristem. I wish not to delve into a genetic examination of the shoot apical meristem but rather into the possible correlation between the apical meristem size and leaf heterophylly. If changes in shoot apical meristem size influence heterophylly in leaves, then as shoot apical meristem changes, leaf characteristics will change. This change may result from two different relationships.

Protozoan Vaccine Candidate Homologues In Tetrahymena Thermophila, Justin Schumacher

Senior Honors Projects

Tetrahymena thermophila is a member of the phylum Ciliophora (the ciliated protozoa) and is currently of great interest due to its unique qualities that make it useful as a model for research directed towards understanding how eukaryotic cells function. Recently, the T. thermophila genome was sequenced, and made available online. Since Tetrahymena is a member of the Alveolata, the major eukaryotic clade that also contains the apicomplexan parasites that cause a number of serious human and animal diseases, we sought to determine whether the genes coding for apicomplexan vaccine candidates were represented in the genome of Tetrahymena. In addition, we …

Biology And Ecology Of Wild Radish (Raphanus Raphanistrum), Mayank Malik

All Dissertations

Wild radish ( L.), a facultative winter annual is a troublesome weed in small grain crops of the Southeastern United States. Besides being a weed, it may also be used as a cover crop for weed management due to its production of glucosinolates. Studies were conducted to evaluate the biology and ecology of wild radish as well as its glucosinolate production and its weed management possibilities.
Wild radish emerging in fall months formed a rosette of leaves which aided its winter survival. Plants emerging from December through March that did not form a rosette had minimal survival. Wild radish life …