Biology Commons^™

Development And Maintenance Of Thymic Epithelial Microenvironment, Varan J. Singh

Dissertations and Theses

Thymus is a primary lymphoid organ responsible for proper development and selection Of T-­‐cells. The thymic microenvironment, however, undergoes age related involution, Resulting in a reduction of the repertoire of T-­‐cells that are produced, and a decreased Capacity to respond to new antigen. Even though significant thymic epithelial turnover occurs, it is unclear if postnatal thymic progenitors/stem cell are responsible for the maintenance of the TEC microenvironment. Here we use the K5rtTA:TetO-­‐H2BGFP transgenic model to identify a slow cycling potential stem cells/progenitor population in the postnatal thymus. These cells were isolated, expanded in culture, and successfully differentiated into adipocytes, chondrocytes …

The Widespread Skink Mabuya Dorsivittata Reveals Complex Patterns Of Genetic Diversity In South America, Danielle Rivera

Dissertations and Theses

No abstract provided.

The Impact Of Forest Successional Status On Community Structure Of Neotropical Cerambycid Beetles, Lin Li

Dissertations and Theses

Due to anthropogenic activities, tropical rain forests face many challenges in sustaining biodiversity and maintaining global climates. This project examines how forest successional status affects community composition of saproxylic cerambycids, which, as early colonists of moribund trees, have an important role in nutrient cycling. In the lowland rain forest of Costa Rica, thirty-nine trees in five plant families (Fabaceae, Lecythidaceae, Malvaceae, Moraceae, and Sapotaceae) were sampled in a mosaic of old growth and secondary forest. They yielded 3545 cerambycid individuals in 49 species. Species richness was almost identical in old growth and secondary forest; but abundance was higher in old-growth. …

Refinement Of Feedforward Projections, Neuronal Density, And Characterization Of Synapsesin Layer 4 Of Ferret Primary Visual Cortex, Violeta Contreras Ramirez

Dissertations and Theses

No abstract provided.

The Drosophila Dynamin, Shibire, Contributes To Blood Cell Division And Differentiation, But May Not Be Required For Host Defence Against Parasitic Wasps, Adam D. Hudgins

Dissertations and Theses

No abstract provided.

Sex Dependent Efficacy Of Taurine As A Treatment For Cocaine Drug Use: A Study Of Reward, Kevin Uribe

Dissertations and Theses

No abstract provided.

An Evaluation Of The Differential Stability Of Nucleic Acids In Biological Fluids Compromised By Degradative Treatments And Environmental Exposure, Tiffany Layne

Master of Science in Forensic Science Directed Research Projects

In an attempt to determine the boundaries of degradation in nucleic acids with increased sensitivity, and provide support for a molecular method for body fluid identification, this study used specific treatments that are commonly found in crime scenes or are present in our daily environment to degrade DNA, messenger RNA, and microRNA in bodily fluids. Recently, the forensic science field has explored the use of RNAs regarding a molecular-based method for forensic body fluid identification. Specifically, messenger RNAs and microRNAs have been researched as markers for body fluids. Messenger RNAs are multifunctional and are shorter than DNA and some are …

Proof-Of-Concept Of Environmental Dna Tools For Atlantic Sturgeon Management, Jameson Hinkle

Theses and Dissertations

Abstract

The Atlantic Sturgeon (Acipenser oxyrinchus oxyrinchus, Mitchell) is an anadromous species that spawns in tidal freshwater rivers from Canada to Florida. Overfishing, river sedimentation and alteration of the river bottom have decreased Atlantic Sturgeon populations, and NOAA lists the species as endangered. Ecologists sometimes find it difficult to locate individuals of a species that is rare, endangered or invasive. The need for methods less invasive that can create more resolution of cryptic species presence is necessary. Environmental DNA (eDNA) is a non-invasive means of detecting rare, endangered, or invasive species by isolating nuclear or mitochondrial DNA (mtDNA) from the …

Consequences Of Vine Infestation: Linking Abiotic Influences And Biotic Interactions To Successional And Structural Changes In Coastal Communities, Spencer N. Bissett

Theses and Dissertations

Located at the interfaces of terrestrial and marine environments, coastal habitats are inherently vulnerable to the effects of global change. Barrier island systems in particular serve not only as protective buffers against storm events, but also as sentinel ecosystems for observation of the impacts of sea level rise, and of increasing storm frequency and intensity. In the mid-Atlantic region, shrub thickets of Morella species compose the dominant forest community. The often monospecific nature of these plant community assemblages is advantageous to ecological studies and cross-scale applications; the relatively low diversity facilitates transitions between scales. My objective was to investigate the …

Testing For Isolation In Florida Raccoons (Procyon Lotor) Using Phylogenetics And Population Genetic Structure, Alexa Trujillo

Electronic Theses and Dissertations

Molecular data are useful in determining if populations are isolated and for species delimitation. Researchers and managers currently recognize five subspecies of raccoons (Procyon lotor) in Florida, based largely on perceived geographic isolation due to the island ranges of four subspecies. In this study, I provide the first estimate of phylogenetic relationships and population divergences within Florida raccoons using a molecular dataset. I analyze the mitochondrial control region, cytochrome b gene, and eight nuclear microsatellite loci to test two hypotheses: 1) the five, morphologically and geographically-defined subspecies of raccoon in Florida represent genetically distinct populations and (2) due to differing …

Does The Journey Matter More Than The Destination? The Contribution Of Geospatial And Local Conditions To Invasive Pomacea Maculata Distribution Across Ranchland Wetlands, Steffan Pierre

Electronic Theses and Dissertations

Geospatial characteristics such as isolation and avenues of connectivity influence an invader's pattern of dispersal and distribution. However many examinations of invasion success ignore the contribution of dispersal to patterns of invasion and focus only on the local environmental/habitat factors. This study examines the interaction of geospatial characteristics, that may influence dispersal, and local environmental factors, that may govern successful occupation, on the likelihood of invasion (invasability) of wetlands within an agriculturally modified landscape. I examined the current invasion of seasonal wetlands in south-central Florida ranchland by non-native apple snails (Pomacea maculata (Ampullariidae)) as a model system for understanding this …

Development Of Human And Rodent Based In Vitro Systems Toward Better Translation Of Bench To Bedside In Vivo Results, Bonnie Berry

Electronic Theses and Dissertations

Prospective medicinal compounds progress through multiple testing phases before becoming licensed drugs. Testing of novel compounds includes a preclinical phase where the potential therapeutic is tested in vitro and/or in animal models in vivo to predict its potential efficacy and/or toxicity in humans. The failure of preclinical models to accurately predict human drug responses can lead to potentially dangerous compounds being administered to humans, or potentially beneficial compounds being kept in development abeyance. Moreover, inappropriate choice in model organism for studying disease states may result in pushing forward inappropriate drug targets and/or compounds and wasting valuable time and resources in …

Identifying Inundation-Driven Effects Among Intertidal Crassostrea Virginica In A Commercially Important Gulf Of Mexico Estuary, Joshua Solomon

Electronic Theses and Dissertations

Sea level rise and changing storm frequency and intensity resulting from climate change create tremendous amounts of uncertainty for coastal species. Intertidal species may be especially affected since they are dependent on daily inundation and exposure. The eastern oyster Crassostrea virginica is an economically and biologically important sessile intertidal species ranging from Canada to the Gulf of Mexico. Declines and changes in distribution of oyster populations has forced commercial harvesting to spread from subtidal to intertidal reefs. We investigated the potential responses of intertidal C. virginica to sea level rise, and the response of larval settlement to sedimentation which is …

A Socio-Economic Assessment Of Marine Turtle Eco-Tourism, Kendra Cope

Electronic Theses and Dissertations

Marine turtles have historically contributed to economic activity through consumptive harvest for food, tools, and decorative objects. Only recently have they begun to benefit humans economically through non-consumptive roles, primarily as a focal point of educational eco-tourism. In recent years, the annual number of turtle walks conducted around the Archie Carr National Wildlife Refuge (ACNWR) has risen. This expansion contributed to a statistically significant increase in attendance from 2,162 in 2001 to 3,047 participants in 2014. I examined the regional economic impacts of marine turtle eco-tourism around the ACNWR using social surveys and an economic impact analysis tool. IMPLAN, an …

Ecophysiological Responses Of Sugar Maple Roots To Climatic Conditions, Mickey Philip Jarvi

Dissertations, Master's Theses and Master's Reports - Open

The severity of future climate change resulting from anthropogenic alteration of the global C cycle will depend in part on feedbacks between atmospheric greenhouse gases and forest ecosystem carbon balance, but how these two systems will interact is not entirely understood. Forests are both major sinks and sources for atmospheric CO₂ through the processes of photosynthesis and ecosystem respiration. The balance between these two processes could be altered if autotrophic respiration were to increase exponentially with temperature as climate warms. Root respiration, and especially fineroot respiration (<1 mm diameter), is a major contributor to total ecosystem C exchange. A study to assess long-term responses of root respiration to warmer soil conditions was conducted at the SMART (sugar maple altered rainfall and temperature) experiment located in Alberta, MI at the Michigan Technological University’s Ford Center and Forest. It was found that acclimation of fine-root respiration in this system was not due to an insufficient supply of carbohydrates from photosynthesis (substrate limitation), but was the result of adenylate control. As a result, fine root respiration was constrained to levels needed to perform work required of the fine roots (e.g. nutrient acquisition). Acclimation also occurred for roots 1-2 mm in diameter at the 0-10 cm soil depth, but not in any roots larger than 2 mm or in roots of any size at deeper soil depths. As a result, at the ecosystem level, total root system respiration was 60% greater in warmed soil than in unwarmed soil. The studies in experimentally warmed sugar maple forests were complemented by an examination of fine-root respiration and root biomass at sixteen sugar maple forests located across a latitudinal gradient across sugar maple’s native range, spanning approximately 10°C of mean annual temperature. Sugar maple in the southern, warmer sites had lower root N, lower specific fine-root respiration at a given temperature, and less fine-root biomass than that from the northern cooler regions. Fine root respiration at ambient soil temperature actually decreased from north to south, despite a nearly 10°C increase in soil temperature. However, within sites respiration measured across three sample dates did increase with temperature. The next big question is whether these adjustments that exist across sugar maple’s range are plastic responses to l local climate or result from genotypic differences among populations in different locations. If the former is true, all sugar maple would be capable of acclimation, reduction in root biomass, and/or reduction in root N as mechanisms for dealing with climatic warming, and sugar maple would have a large capacity to adjust to future climate change. The latter would suggest that predicted rates of climatic warming could have negative impacts on this important species across its entire current range. The lack of changes in fine root biomass and root N concentration at the SMART study location after four plus years of soil warming support the possibility that differences along the latitudinal transect are largely the result of inherent genetic differences among population.

Mia40 Protein Serves As An Electron Sink In The Mia40-Erv1 Import Pathway, Sonya E. Neal, Deepa V. Dabir, Heather L. Tienson, Darryl M. Horn, Kathrin Glaeser, Rachel R. Ogozalek Loo, Antoni Barrientos, Carla M. Koehler

Biology Faculty Works

A redox-regulated import pathway consisting of Mia40 and Erv1 mediates the import of cysteine-rich proteins into the mitochondrial intermembrane space. Mia40 is the oxidoreductase that inserts two disulfide bonds into the substrate simultaneously. However, Mia40 has one redox-active cysteine pair, resulting in ambiguity about how Mia40 accepts numerous electrons during substrate oxidation. In this study, we have addressed the oxidation of Tim13 in vitro and in organello. Reductants such as glutathione and ascorbate inhibited both the oxidation of the substrate Tim13 in vitro and the import of Tim13 and Cmc1 into isolated mitochondria. In addition, a ternary complex consisting …

Patterns Of Testosterone In Three Nearctic-Neotropical Migratory Songbirds During Spring Passage, Kristen M. Covino

Biology Faculty Works

Preparation for breeding may overlap extensively with vernal migration in long-distance migratory songbirds. Testosterone plays a central role in mediating this transition into breeding condition by facilitating changes to physiology and behavior. While changes in testosterone levels are well studied in captive migrants, these changes are less well known in free-living birds. We examined testosterone levels in free-living Nearctic-Neotropical migrants of three species during their vernal migration. Testosterone levels increased during the migratory period in males of all three species but significantly so in only two. Testosterone levels in females remained the same throughout their migration. Our results support the …

Fall Migratory Patterns Of The Blackpoll Warbler At A Continental Scale, Kristen M. Covino

Biology Faculty Works

Blackpoll Warblers (Setophaga striata) breed across Canada and the northern United States and fly across the Atlantic Ocean to South America in fall. Studies of fall migration in this species have centered on the extensive overwater flights but have ignored other aspects of this migration, including potential geographic variation. We used Blackpoll Warbler banding records from 3 coastal (Atlantic seaboard) sites and 9 inland sites to study the fall migration. The sites covered a wide range of the species' geographic distribution during breeding and fall migration in North America. The data spanned the years 1967-2013, though the particular years sampled …

Effects Of Sex And Mycorrhizal Fungi On Gas Exchange In The Dioecious Salt Marsh Grass Distichlis Spicata, Kassandra Reuss-Schmidt, Todd N. Rosenstiel, Sally R. Rogers, Allie G. Simpson, Sarah M. Eppley

Biology Faculty Publications and Presentations

Premise of research. In dioecious plant species, males and females often differ in physiology, and mycorrhizal fungal relationships are likely to influence these differences. However, few data are available on the potential role of mycorrhizal fungi in altering sex-specific physiology and population sex ratios of dioecious plant species.

Methodology. In this study, we measured leaf gas exchange in a multifactorial greenhouse experiment with and without mycorrhizal fungal additions and under field conditions in Distichlis spicata, a dioecious C4 salt marsh grass, displaying extreme spatial sex ratio variation.

Pivotal results. We found a significant interaction between gas exchange, plant sex, and …

Ph Dependent Antibiotic Resistance Of An Alkaliphilic, Halotolerant Bacterium Isolated From Soap Lake, Washington, Tiffany Charlynn Edwards

Masters Theses

"Soap Lake, located in Washington State, is a meromictic, soda lake. Many bacterial isolates retrieved from Soap Lake have been noted to possess resistance to multiple antibiotics. A likely explanation for the wide range of antibacterial resistance exhibited by these strains is due to the impact of high alkalinity on the antibiotics themselves and not due to the presence of antibiotic resistance genes. The aim of our study was to determine if select antibiotics are effective against Halomonas eurialkalitoleranis, a bacterium capable of growth over a wide range of neutral to alkaline pH values, to investigate the influence of alkalinity …

Healing Of Bone Defects In A Rodent Calvarial Defect Model Using Strong Porous Bioactive Glass (13-93) Scaffolds, Yinan Lin

Masters Theses

"The main objective of this project was to evaluate the capacity of strong porous silicate (13-93) bioactive glass scaffolds prepared by a robocasting technique to regenerate bone and stimulate angiogenesis in a rat calvarial defect model. The scaffolds were created with the same grid-like microstructure but in a variety of formulations: (i) as-fabricated, (ii) pretreated in an aqueous phosphate solution to convert the glass surface to hydroxyapatite, (iii) loaded with bone morphogenetic protein-2 (BMP2) (1 µg per scaffold), and (iv) doped with copper (0.4-2.0 wt. % CuO). When compared to the as-fabricated scaffolds, the pretreated scaffolds enhanced bone regeneration at …

Extreme Tolerance And Developmental Buffering Of Uv-C Induced Dna Damage In Embryos Of The Annual Killifish Austrofundulus Limnaeus, Josiah Tad Wagner, Jason E. Podrabsky

Biology Faculty Publications and Presentations

Free-living aquatic embryos are often at risk of exposure to ultraviolet radiation (UV-R). Successful completion of embryonic development depends on efficient removal of DNA lesions, and thus many aquatic embryos have mechanisms to reverse DNA lesions induced by UV-R. However, little is known of how embryos that are able to enter embryonic dormancy may respond to UV-R exposure and subsequent DNA damage. Embryos of the annual killifish Austrofundulus limnaeus are unique among vertebrates because their normal embryonic development includes (1) a complete dispersion of embryonic blastomeres prior to formation of the definitive embryonic axis, and (2) entry into a state …

Multi-Locus Phylogeny Of The Afrotropical Freshwater Crab Fauna , Savel Regan Daniels Phd, E E. Phiri, Sebastian Klaus Phd, C Albrecht, Neil Cumberlidge

Journal Articles

No abstract provided.

New Collections Of Freshwater Crabs From Northern Madagascar, With The Description Of A New Species Of Foza Reed & Cumberlidge, 2006 (Brachyura, Potamonautidae), And Comments On Their Conservation Status, Neil Cumberlidge, Sebastian Klaus, Kirstin S. Meyer, Jennifer C. Kroppin

Journal Articles

No abstract provided.

The Impact Of Photopollution On Nesting Loggerhead Sea Turtles (Caretta Caretta) Along The Grand Strand, South Carolina, Ryan Bonner

Electronic Theses and Dissertations

Photopollution present along heavily developed coastlines is known to have a significant negative impact on nesting sea turtle populations by damaging nesting habitat quality, but few studies have explored this relationship on broad spatial scales. The purpose of this study was to characterize the onshore light field along a developed stretch of South Carolina coastline and to quantify how photopollution intensity affects regional loggerhead sea turtle (Carretta carretta) nesting density using historical nesting data. Light measurements were collected using a portable low-light photometer at 74 sites spaced at approximately one km intervals across the study area. At each site, the …

The Fish Kill Mechanism Of The Harmful Raphidophyte Chattonella Subsalsa, Amy E. Grogan

Electronic Theses and Dissertations

Harmful algae blooms (HABs) and toxins associated with HAB species are a significant threat to the health of marine species and coastal environments. In the South Carolina coastal zone, HABs have proliferated with intensified anthropogenic eutrophication in coastal waters. The raphidophyte species Chattonella subsalsa is a prominent cause of algal blooms resulting in fish kills in South Carolina. Though C. subsalsa is a known ichthyotoxic alga, the fish kill mechanism of this species remains unidentified. C. subsalsa is likely to elicit fish mortality via one of two mechanisms: (1) gill damage induced by cell contact irritation or (2) the production …

Chemical And Behavioral Ecology Of The Coastal Giant Salamander (Dicamptodon Tenebrosus), David Reavill

All Master's Theses

Intraspecific interactions are an important factor in shaping the population structure of terrestrial salamanders. Both physical interactions and scent-marking are vital components to the establishment of territories and influence dispersion of individuals. However, little is known about the terrestrial interactions of many salamander species, particularly that of the Coastal Giant Salamander (Dicamptodon tenebrosus). In this study, I observed the first evidence for the use chemical cues by terrestrial D. tenerosus in regards to shelter selection. I also observed the first accounts of agonistic and display behavior of terrestrial D. tenebrosus. These results suggest that terrestrial D. tenebrosus …

Androgen Mediation Of Elaborate Male Traits: The Effects Of Dihydrotestosterone Administration On Vocal Quality In Male Green Treefrogs, Hyla Cinerea, Thor M. Goodfellow

Honors Theses

Elevated androgen levels are well known to mediate the expression of male courtship behaviors and elaborate traits, but whether androgens act via threshold or graded effects is less clear. Models linking elaborate male traits to the endocrine system often assume that androgens have a graded effect on the magnitude or extent of elaborate male traits and that female preference for more elaborate male traits thus drives concordant directional selection on circulating androgen levels. To test this hypothesis, I examined the effects of dihydrotestosterone (DHT) administration on the quality of advertisement calls produced by male Hyla cinerea. Advertisement calls are an …

Modeling Atp-Binding Cassette G2 (Abcg2) Substrate Specificity, Raghav D. Acharya, Aurijit Sarkar, Glen E. Kellogg

UROP Posters

How well can we predict efflux by ATP-binding cassette G2?

It is estimated that there will be about 1.6 million new cases of cancer and half a million cancer deaths in the US during 2015.ATP-binding cassette (ABC) efflux transporters such as ABCG2 are overexpressed in chemotherapy-resistant cancer cells. Anticancer drugs are prone to efflux by these transporters. Being able to identify drugs that are effluxed is of great interest in drug discovery.The current arsenal of methods used to detect efflux are not easily adaptable to high throughput formats and are limited in scope, making experimental analysis an expensive prospect. Hence, …

Smoking Patterns Among Vcu Students, Jasmine Saini

UROP Posters

For some individuals, college can be a high risk time for the development of problems associated with alcohol use and other substances. The purpose of this study is to examine these initiation and use patterns as they relate to nicotine use among college students 18 years of age and older enrolled in Spit for Science: The VCU Student Survey. The Spit for Science research project evaluates how genetic and environmental factors contribute to substance use and emotional health among college students at VCU. This study uses data from the Spit for Science 2011 cohort (n=2007) to investigate smoking patterns among …