Biology Commons^™

Planar Cell Polarity And Neurodevelopment, Simon Sun

Theses and Dissertations

Planar cell polarity (PCP) is a developmental signaling mechanism that establishes a polarity within the plane of an epithelium. PCP has been shown to play a role in guiding numerous neurodevelopmental processes such as convergent extension, neuron migration, and axon pathfinding. Certain commissural neurons in the dorsal spinal cord make a series of guidance decisions en route to the brain: first, a ventral projection along the D-V axis, followed by a midline crossing, and after exiting the floorplate, a dorso-anterior turn along the A-P axis. Here, we provide in vivo evidence that the axons of the Commissural Primary Ascending (CoPAs) …

Understanding The Role Of Stylochus Ellipticus As A Predator Of Crassostrea Virginica In Chesapeake Bay Tributaries, Marion Kensey Barker

Theses and Dissertations

Predation may be a key component of the unsuccessful restoration of the Eastern Oyster (Crassostrea virginica), a former keystone species in Chesapeake Bay. Here, I examine the polyclad flatworm Stylochus ellipticus and its potential role as an important predator of C. virginica. Using small-fragment size C. virginica specific DNA primers, oyster DNA was successfully detected in whole organisms homogenates of wild-caught S. ellipticus individuals. Of the 1,575 individuals tested, 68.1% tested positive, thus predation occurred. Predation did not appear to be affected by salinity or temperature; however, season did appear to have an effect on both predation and S. ellipticus …

Benthic Macroinvertebrate Subsampling Effort And Taxonomic Resolution For Bioassessments Of Streams In The James River Watershed Of Virginia, Laurel Williams

Theses and Dissertations

Benthic macroinvertebrate diversity influences stream food web dynamics, nutrient cycling and material exchange between the benthos and the water column. Stream bioassessment has moved to the forefront of water quality monitoring in terms of benthic macroinvertebrate diversity in the recent past. The objectives of this study were to determine optimum subsample size and level of taxonomic resolution necessary to accurately and precisely describe macroinvertebrate diversity in streams flowing in the Piedmont province of the James River watershed in Virginia. Forty-nine sampling sites were selected from streams within the Piedmont Physiographic Province of the James River watershed. Ten sites were randomly …

Conspecific Attraction In A Low-Density Population Of A Threatened Songbird, Daniel James Albrecht-Mallinger

Theses and Dissertations

Many organisms use both vegetation structure and social cues in selecting habitats. Many species of songbirds use the presence of breeding conspecifics as a social cue and sign of habitat quality, and can be induced to settle in unoccupied habitats by artificially broadcasting breeding song, a process referred to as “conspecific attraction”. In our study, we tested response to conspecific attraction a low-density population of the threatened Golden-winged Warbler (Vermivora chrysoptera) in Highland County, VA. Response to broadcast song was observed, with a modest increase in mean male abundance at survey points within 250 meters of treatments, and mean abundance …

Indirect Effects Between Deer, Mice, And The Gypsy Moth In A Forest Community, John Wojcikiewicz

Theses and Dissertations

White-tailed deer are ecosystem engineers that dramatically alter forest understory vegetation. Consequently, deer can impact many species in a forest through both direct and indirect effects. One species that deer may indirectly affect is the gypsy moth, whose pupae are preyed upon by the white-footed mouse. Through alterations to understory habitat of mice, deer may reduce mouse predation on gypsy moth pupae. In this study, I tested for indirect effects of deer on the gypsy moth by comparing mouse abundance, vegetation properties, and predation on pupae inside, and outside, of long-term deer exclosures. Overall, I did not find evidence for …

Forest Net Primary Production Resistance Across A Gradient Of Moderate Disturbance, Ellen Goodrich-Stuart

Theses and Dissertations

The global carbon (C) balance is vulnerable to disturbances that alter terrestrial C uptake and loss. Moderate disturbances that kill or defoliate only a subset of canopy trees such as insect defoliation, drought, and age-related senescence are increasing in extent and frequency; yet, little is known about the effect of moderate disturbance on forest production and the mechanisms sustaining or supporting the recovery of the C cycle across a range of moderate disturbance severities. We used a broad plot-scale gradient of upper canopy tree mortality within a large manipulation of forest disturbance to: 1) quantify how aboveground wood net primary …

The Occurrence And Consequences Of Conspecific Brood Parasitism In The Prothonotary Warbler (Protonotaria Citrea), Anna Tucker

Theses and Dissertations

Brood parasites avoid costs associated with raising young by adding eggs to another individual’s clutch and providing no parental care. When conspecific brood parasitism occurs in species with high parental investment, we expect hosts to suffer costs for raising an enlarged brood. Here I describe conspecific brood parasitism (CBP) in the prothonotary warbler using maternal exclusion analyses of 333 family groups. I found that 23.4% of clutches contained at least one offspring that was not matched to the social mother and determined that parasitism seems to be an opportunistic tactic. Hosts had lower average annual reproductive success than non-hosts, but …

Forest Edges Enhance Mate-Finding In The European Gypsy Moth, Lymantria Dispar, Lily Thompson

Theses and Dissertations

Understanding movement capabilities of individuals within a landscape is essential to identifying the effects of habitat boundaries on species abundances, ranges, and spread rates. Movement barriers due to habitat fragmentation may reduce mate-finding ability in some species, particularly in heterogeneous landscapes containing low-density populations. This study focuses on the effects of habitat type and edge on mate-finding in an invasive defoliator, the European gypsy moth. Adult European gypsy moth males locate mates by following pheromones released by flightless females. Reduced mate-finding was expected in fields and near forest edges based on geographic variation in invasion rates and pheromone plume dynamics. …

Using Deuterium And Garp To Estimate Geographic Extents Of Source Populations Of Hoary ( Lasiurus Cinereus ) And Eastern Red ( Lasiurus Borealis ) Bats Killed At A Central Illinois Wind Facility, Rachael Anne Van Essen

Theses and Dissertations

High bat mortality at wind energy facilities is a widely cited conservation issue, but the population-level impacts are not understood. In Illinois, the main species affected are migratory tree bats like the Hoary (Lasiurus cinereus) and Eastern Red (Lasiurus borealis).This research used deuterium isotope analysis of hair combined with ecological niche modeling (GARP: Genetic Algorithm for Rule-set Prediction) in a novel way to map the geographic extents of Hoary and Eastern Red bat specimens salvaged at a single central Illinois wind facility from 2008-2010. Hair was chosen after determining that the claw is currently a problematic tissue due to a …

The Effects Of Invasive Macrophytes Phragmites Australis And Typha Angustifolia On Nitrate Removal In High Nitrate Wetland Sediments, Lauren Mackenzie Beal

Theses and Dissertations

Constructed wetlands are quickly becoming inundated with invasive species like Phragmites australis and Typha angustifolia which are capable of changing whole ecosystem function and community composition. We wanted to assess how plants affect dissolved oxygen (DO) and dissolved organic carbon concentrations (DOC), and in turn if they increase nitrate (NO3-N) removal rates relative to barren sediments. Using a NO3-N/Br tracer test, we tested NO3-N removal rates, DO, and DOC concentrations. After the tracer test, we measured above- and below-ground plant biomass and sediment characteristics. NO3-N removal did not differ across the treatments. Phragmites australis microcosms had significantly higher sediment bulk …

Identification Of Transcriptionally Quiescent Regions In The Neurospora Crassa Genome, Katie Marie Groskreutz

Theses and Dissertations

Sexual reproduction and genetic exchange via meiosis are important and highly conserved processes in many living organisms. Occasionally, complications occur during meiosis that can result in chromosome abnormalities. In humans, improper chromosome development can cause life altering disorders such as Down Syndrome, Edwards Syndrome, and Patau Syndrome. Unfortunately, despite its importance, gaps remain in our knowledge of how this process works. For instance, little is known about how homolog identification occurs and what proteins identify matching chromosomes during pairing. This fundamental process occurs early during meiosis and ensures proper development of gametes.

Understanding the proteins involved during homolog pairing may …

Hydroxocobalamin Treatment For Carbon Monoxide Exposures: Characterizing Hemoglobin Changes And Testing For Neurological Sequelae, Leonardo Somera

Theses and Dissertations

Prior work in our lab has indicated that reduced Hydroxocobalamin (B12r) can be added to human blood and is able to convert carbon monoxide (CO) into carbon dioxide. This has great potential as a direct antidote to mitigate the toxic effects of CO poisoning which is a public health risk. In the first part of our work, we use highly specific wavelengths of light and Raman spectroscopy to study changes in Carboxyhemoglobin (COHb) between blood treated with oxygen and blood treated with oxygen and B12r in a flowing circuit of blood. Using Raman spectroscopy, we found that the addition of …

Studies On Theraputic Potential Of Dichloroacetic Acid And Hene Laser In Cancer Treatment: Understanding The Mechanism Of Action, Zeiyad Nassaif Al-Karakooly

Theses and Dissertations

Cancer cells are often characterized by anaerobic glycolysis due to dysfunctional mitochondria that limits pyruvate uptake for aerobic respiration. Dichloroacetic acid (DCA), used in this study as a potential cancer treatment agent, targets mitochondria in cancer cells and is likely to correct mitochondrial dysfunction by resuming pyruvate uptake and therefore normal aerobic respiration. Our results suggest that DCA causes a significantly higher cytotoxicity in aggressive MCF-7 breast cancer cells than in non-aggressive MC3T3 osteoblastic cells. Apparently lower doses of DCA induce apoptosis whereas higher doses lead to non-specific cytotoxicity or necrosis. Increased cytotoxicity might be related to oxidative stress due …

The Effect Of Fluvastatin On Mast Cell Function: Genotype Dependence, Elizabeth M. Kolawole

Theses and Dissertations

Fluvastatin, the HMG-CoA reductase inhibitor known for its role in the treatment of hypercholesterolemia and cardiovascular disease, has more recently been shown to play a role in the immune response. Given the critical role that mast cells play in allergy and inflammatory diseases such as asthma, which effects one third of America’s population, we assessed the effect of fluvastatin on mast cell and basophils function. We demonstrate that fluvastatin downregulated IgE-mediated cytokine production. Additionally, in vivo studies showed that fluvastatin suppressed IgE-mediated anaphylaxis. Interestingly, the effects of fluvastatin showed dependence on genetic background, as C57BL/6 mast cells were sensitive, while …

The Role Of Nitric Oxide Scavenging In Hemoglobin-Based Oxygen Carrier Induced Hypertension: Systemic And Microvascular Effects, Alan Ottarson

Theses and Dissertations

The purpose of this study was to identify the effects of a hemoglobin-based oxygen carrier, HBOC-201, on the cardiovascular system. Systemic cardiovascular parameters of mean arterial pressure (MAP), pulse pressure, heart rate, and oxygen saturation, as well as vascular resistance, were examined. A murine model of the cardiovascular system and microvasculature was employed. Sprague-Dawley rats (male; 230-530g; N = 13) were anaesthetised and surgically prepared for intravital microscopy of the spinotrapezius muscle. Increasing doses of HBOC-201 (2 mg/kg, 22 mg/kg, 230 mg/kg, and 780 mg/kg) and an iso-oncotic volume control were administered to assess for a dose-response relationship. MAP displayed …

Historical Tidal Forest Composition And Contemporary Woody Recruitment Following Dam Removal From A Mid-Atlantic Coastal Plain Tidal Freshwater Wetland, Richard E. Ward Jr.

Theses and Dissertations

Tidal freshwater forest restoration after dam removal has been unexplored to date. This study elucidated pre-dam forest composition, as well as post-dam edaphic and microtopographical attributes and woody species recruiting along a narrow ecotone of a 29.3-ha tidal freshwater wetland. The ≈65-year-old historical forest (15 species, 200 stems ha-1) and ≈7-year-old contemporary forest (40 species and 11,009 stems ha-) community dominants were dissimilar (Fraxinus spp. vs. Liquidambar styraciflua, respectively). Pre-dam environmental conditions were unknown. Post-dam edaphic water content, organic matter, redox potential and microtopography differed significantly across tidal sites but were less variable in non-tidal sites. Shifts in the contemporary …

"Mining" For A Reference Condition In Southern West Virginia Streams, Matthew Rouch

Theses and Dissertations

Quarterly samples were used to estimate assemblage-level (all species combined) fish production within three minimally-impacted, southern West Virginia streams. The total annual fish production estimate was highest in Slaunch Fork (37.52 kg∙ha^-1∙y^-1), a tributary of the Tug Fork River, and lowest in Cabin Creek (10.59 kg∙ha^-1∙y^-1), a Guyandotte River tributary. Creek Chub Semotilus atromaculatus, Mottled Sculpin Cottus bairdii and Blacknose Dace Rhinicthys atratulus were the most abundant species among sites, accounting for >90% of all sampled individuals. Reference condition criteria were also selected and metrics calculated for each of the three …

The Response Of Naive Channel Catfish To Chemical Cues Associated With Predation, Marinda Coulter

Theses and Dissertations

The chemosensory abilities of fishes, are important in order to understand how prey can perceive and avoid predators. Predator-naïve Channel catfish were exposed to four extracts over eight sessions (naïve bass water (NBW), bass that were fed catfish water (BFCW), catfish skin extract (CS), and naïve bass water paired with catfish skin extract (CO)) to determine whether they have an innate predator response to potential chemical cues indicating possible predation risk. Movement was quantified as grid squares crossed, directional changes, and tail beats. Response increased during the first minute following stimulus injection and decreased during the second minute. Channel catfish …

Who's Your Daddy? A Study Of Extra-Pair Copulation And Mating Behaviors Of Protonotaria Citrea, Morton Catherine Heidrich

Theses and Dissertations

Mating behavior has a profound impact on reproductive success and the resulting genetic structure of offspring. Extra-pair copulation is a widely observed behavior within avian species. This study explored the genetic effects of mating behaviors of Prothonotary warblers, Protonotaria citrea (Parulidae), using co-dominant microsatellite markers. Prothonotary warblers are migratory songbirds that build nests in cavities, commonly found in wetland habitats. A set of artificial nest boxes were initiated by Dr Robert Reilly in 2002 in Dutch Gap, Chesterfield County Virginia, USA, a tidal tributary off the James River. From this population, 28 nest boxes were surveyed yielding 47 adults and …

The Effects Of Isolation On Endemic Cozumel Island Rodents: A Test Of The Island Rule, Brittany Marie Nuttall

Theses and Dissertations

Island isolation can cause changes in body size, cranial characteristics, and genetic variation in mammals. We use geometric morphometrics to test skull and mandible shape and size change across three species of endemic Cozumel Island rodents in order to test the “island rule” of larger size in isolated rodents. We also sequenced the D-Loop and cytochrome b region of the mitochondrial genome and tested for differences in genetic variation between island and mainland groups, as well as population structure and gene flow in order to assess the effect of island isolation on these three rodents. We found that the three …

Application Of Next-Generation Transcriptomic Tools For Non-Model Organisms: Gene Discovery And Marker Developmentwithin Plecoptera (Insecta), Nicholas Gregory Davis

Theses and Dissertations

Phylogenetic research on non-model organisms has been hindered by limited marker availability. Next generation sequencing techniques are eliminating that barrier. Using Illumina sequencing technology, Trinity assembly software, custom Perl reciprocal BLAST scripts, and Primer3 primer prediction software, we produced and analyzed 7 Plecopteran transcriptomes, representing 7 of the 16 total families, in an attempt to identify and develop conserved orthologous genetic markers. The transcriptomes were used to reconstruct a gene content phylogeny using a simple distance matrix generated from reciprocal blastn data. By producing and filtering a reciprocal blast network we identified and aligned over 450 putative orthologs. Out of …

An Investigation Into The Presynaptic Actions By Which Amphetamine Activates Dopamine Signaling Within Striatal Subregions Of The Rat., Dan P. Covey

Theses and Dissertations

Despite decades of intense research and a consensus view in the field, the work presented herein provides strong evidence that the primary mechanism of amphetamine action should be re-evaluated. Rather than depleting vesicular dopamine stores and promoting non-exocytotic efflux through the dopamine transporter in vivo, recent evidence demonstrates that amphetamine augments phasic dopamine signaling instead. This signaling modality is critical for reinforcement learning and is dependent on intact vesicular stores. The new findings support over-activation of phasic dopamine signaling as a common mechanism in the addiction process.

Confocal Microscopy Study Of The Embryonic Development Of The Viviparous Nemertean Prosorhochmus Americanus Reveals Larval Features Supporting Indirect Development In Hoplonemerteans, S Tyler Spindle

Theses and Dissertations

Recent studies of hoplonenemertean planuliform larvae have clarified their development and provided insight into larval evolution within the phylum. However, an assessment of viviparous development using modern techniques is lacking. To help facilitate a comprehensive comparative evaluation of developmental diversity within hoplonemerteans, we have conducted a confocal laser scanning microscopy investigation of the development in Prosorhochmus americanus, one of the few viviparous hoplonemertean species. Phalloidin staining provides evidence of a modified transitory larval epidermis, and reveals that the foregut, midgut, proboscis, central nervous system, and body wall musculature form early in development, consistent with observations for planktonic and encapsulated hoplonemertean …

Environmental Influences On Sex Ratio And Spatial Distribution Of Dioecious Morella Cerifera L. On A Virginia Barrier Island., Molly Hokkanen

Theses and Dissertations

For dioecious plant species, sex ratios within a population depend on multiple environmental and life history characteristics. Sex ratio is an indicator of population health and can be a predictor for genetic bottlenecking. My study established the previously unknown sex ratio for the shrub, Morella cerifera, on a Virginia barrier island. The ratio was compared with multiple environmental and reproductive traits to determine their potential influence on sex determination and/or distribution of male and female plants. Multivariate analyses were used to identify relationships between sex, sex ratio and environmental drivers. The sex ratio for M. cerifera changed depending on scale. …

Development Of Pectoral Apparatus In Ictalurid Catfish, Shweta Lahiri

Theses and Dissertations

The thesis contains two manuscripts- 1) Developmental changes in pectoral muscle fiber diameter and number in the Blue Catfish, Ictalurus furcatus and 2) Reduction in pectoral spine and girdle in domesticated Channel Catfish, Ictalurus punctatus is likely caused by the absence of fish predators. The first study showed that fiber diameter increased linearly with fish size, whereas fiber number increases non linearly with fish size in the Blue Catfish correlated with dietary shift. The second study showed shorter spines in domesticated Channel Catfish as compared to wild Channel Catfish was a result of reduction in selection pressure during domestication in …

The Effects Of Saltwater Intrusion On Methanogen Community Abundance, Structure, And Activity, Jaimie Gillespie

Theses and Dissertations

Tidal freshwater wetlands (TFW) are at significant risk of loss or alteration due to global climate change, and saltwater intrusion from sea level rise is of particular concern for these habitats due to their proximity to coastal areas. A space-for-time model was used to investigate the effects of saltwater intrusion on soil methanogen communities along naturally occurring salinity gradients on the Waccamaw, James, and Hudson Rivers. Amplification of the methyl coenzyme-M reductase (mcrA) functional gene was used in qPCR, reverse transcription qPCR, and T-RFLP to measure the abundance, activity, and community composition of soil methanogens. Both the abundance and activity …

Phylogeography And Species Status Of Ramphogordius Sanguineus, Cora Runnels

Theses and Dissertations

Ramphogordius sanguineus (Rathke 1799) is a gregarious nemertean with a worldwide distribution and found mainly on hard substrates associated with mussels, oysters and other organisms of the fouling community. Asexual reproduction occurs by spontaneous fragmentation and only anecdotal accounts of sexual reproduction exist. This is the first phylogeographic study of R. sanguineus as well as the first species delimitation analyses employing DNA markers. Analysis of the mitochondrial gene nad6 and nuclear ISSR markers showed little diversity among geographically widespread populations, but AMOVA analyses of both markers revealed moderate to high genetic differentiation. Populations from Maine and Massachusetts exhibited the highest …

Biogeography And Evolution Of Neotropical Small Mammals, With Emphasis On Hystricognath Spiny Rats Of The Genus Proechimys (Family Echimyidae), Rafael Do Nascimento Leite

Theses and Dissertations

The Neotropical region is the most biologically diverse region on the planet. The region encompasses a variety of ecosystems and has long been the target of researchers interested in patterns of species diversity and distribution. More recently, molecular data have been incorporated into methods for reconstructing the historical relationships among geographical areas and their biotas. Molecular phylogenetics has provided insights into diversification patterns and the influence of Late Cenozoic events on the evolutionary history of the region. Nevertheless, considering the vast extent and complexity of the region, more studies are needed to fully appreciate the patterns of biogeography and the …

Personhood And Cloning: Modern Applications And Ethics Of Stem Cell And Cloning Technology, Sariah Cottrell Mccarrey

Theses and Dissertations

Within many communities and religions, including the LDS community, there is some controversy surrounding the use of stem cells – particularly embryonic stem cells (ESC). Much of this controversy arises from confusion and misconceptions about what stem cells actually are, where they come from , and when life begins. The theology of the Church of Jesus Christ of Latter-day Saints has interesting implications for the last of these considerations, and it becomes less a question of “when does life begin” and more an exploration of “when does personhood begin” or “when does the spirit enter the body.” With no official …

Analysis Of Synephrine Content In Bitter Orange (Citrus Aurantium L.) Dietary Supplements, Martha L. Newell

Theses and Dissertations

Many Americans are either currently taking, or have recently taken, non-prescription dietary supplements. These supplements claim to help prevent or relieve any number of ailments, but are not regulated by any governing body. One common use of dietary supplements is to aid in weight loss. Synephrine, the most abundant active component in bitter orange (Citrus aurantium L.) extracts, became a regular ingredient in weight loss supplements after the 2004 ephedra ban. The initial goal of this research was to use reverse phase high performance liquid chromatography (HPLC) to determine the synephrine content of five dietary supplements and compare …