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Articles 1 - 30 of 31
Full-Text Articles in Biology
Distribution And Molecular Analysis Of Avian Malaria Vectors On Four Central Virginia Prothonotary Warbler (Protonotaria Citrea) Breeding Sites, Catherine Wallace
Distribution And Molecular Analysis Of Avian Malaria Vectors On Four Central Virginia Prothonotary Warbler (Protonotaria Citrea) Breeding Sites, Catherine Wallace
Theses and Dissertations
Avian malaria is a devastating disease that has decimated numerous bird species. This study sought to identify the vectors of avian malaria at four central Virginia Prothonotary warbler breeding sites. Twenty one thousand mosquitoes were collected and Culex salinarius, Cx. erraticus, and Cx. pipiens/restuans were found to be the dominant species at these sites. Geographic factors, such as crop land and forest type, were determined to be potential indicators for species abundance variation between sites. Of the mosquitoes collected, ninety one (0.4%) were identified as blood fed. The blood fed mosquitoes were found to have fed on avian, mammalian, amphibian, …
Gene Flow And Dispersal Of The Flatworm, Polycelis Coronata: A Multiscale Analysis, Jeffrey N. Moore
Gene Flow And Dispersal Of The Flatworm, Polycelis Coronata: A Multiscale Analysis, Jeffrey N. Moore
Theses and Dissertations
We determined genetic variance and gene flow across multiple scales (reaches, headwater segments, and catchments) to examine the dispersal ability of the flatworm Polycelis coronata along the Wasatch Mountains of Utah. Multiple models predict patterns of genetic differentiation in stream invertebrates based on dispersal traits and the spatial connectivity of the habitat. The stream hierarchy model predicts genetic differentiation to be low and gene flow to be high between reaches nested in segments, moderate among segments within catchments, and differentiation to be highest and gene flow lowest among catchments, whereas the headwater model predicts the greatest differentiation between headwater segments. …
Depth And Time Related Variations Of Microbial Communiites In An Emergent Freshwater Wetland, Amy Jenkins
Depth And Time Related Variations Of Microbial Communiites In An Emergent Freshwater Wetland, Amy Jenkins
Theses and Dissertations
Soils, and the microbial communities contained within them, are vital for most chemical, physical, and biological processes. This study investigated how microbial community structure responded to environmental changes, such as hydrology, across vertical space (depth) and time in an emergent fresh water wetland. Research was conducted in a non-tidal freshwater wetland along the James River (Charles City County, Virginia) by establishing plots in two areas that experienced different hydrologic regimes and plant communities. Soil cores (30 cm) were collected monthly from January 2008 to February 2009, and then every two to three months thereafter until October 2009, for a total …
Antimicrobial And Anticancer Activity Of Essential Oils From Guatemalan Medicinal Plants, Andrew B. Miller
Antimicrobial And Anticancer Activity Of Essential Oils From Guatemalan Medicinal Plants, Andrew B. Miller
Theses and Dissertations
Guatemalan medicinal plants were collected and screened for the presence of essential oils using steam distillation. Oil was found in 63 species from 24 families and was tested in tube dilution assays for activity against Escherichia coli, Staphylococcus aureus, Streptococcus mutans, Lactobacillus acidophilus and Candida albicans. Several essential oils were highly active with 20 instances of oils inhibiting the microbes at an MIC of 0.31 µl/ml. Oils were also tested against cancerous and established cell lines using a 15% (v/v) agar-media which was developed to improve essential oil solubility. Assays were performed against three cancer lines: …
Predicting The Distribution Of Air Pollution Sensitive Lichens Using Habitat Niche Modeling, Gajendra Shrestha
Predicting The Distribution Of Air Pollution Sensitive Lichens Using Habitat Niche Modeling, Gajendra Shrestha
Theses and Dissertations
Usnea hirta and Xanthoparmelia cumberlandia are commonly used as bio-monitors of air quality. In order to more accurately and efficiently determine the distribution of these two sensitive indicator species, we have developed a probabilistic distribution map as a function of 9 macroclimatic and topographic variables for the White River National Forest, Colorado using Non-Parametric Multiplicative Regression (NPMR) analysis. Furthermore, we also developed a logistic regression (LR) model for X. cumberlandia in order to evaluate the strengths and limitations of the NPMR model. The best model for U. hirta included four variables - solar radiation, average monthly precipitation, average monthly minimum …
Model Detection Based Upon Amino Acid Properties, Kit J. Menlove
Model Detection Based Upon Amino Acid Properties, Kit J. Menlove
Theses and Dissertations
Similarity searches are an essential component to most bioinformatic applications. They form the bases of structural motif identification, gene identification, and insights into functional associations. With the rapid increase in the available genetic data through a wide variety of databases, similarity searches are an essential tool for accessing these data in an informative and productive way. In our chapter, we provide an overview of similarity searching approaches, related databases, and parameter options to achieve the best results for a variety of applications. We then provide a worked example and some notes for consideration. Homology detection is one of the most …
Canopy Disturbance And Reproduction In Cornus Florida L., Daniel Carr
Canopy Disturbance And Reproduction In Cornus Florida L., Daniel Carr
Theses and Dissertations
This study examined aspects of local reproductive variation in the flowering dogwood (Cornus florida L.) coincident with recent differences in primary canopy architecture. The dogwood trees in this study were impacted by a hurricane that created numerous treefall gaps, which created fine scale heterogeneity in the primary canopy. Fine scale disturbances in a forest can result in changes for multiple members of the forest community, including the reproductive responses of the trees and interspecific pollination mutualisms. Previously determined differences in offspring genetic structure suggested that pollen movement among genetically unstructured maternal individuals was significantly impacted between open, or disturbed, canopy …
Effect Of Ph On The Transcriptional Profile Of Porphyromonas Gingivalis W83, Nathan Maietta
Effect Of Ph On The Transcriptional Profile Of Porphyromonas Gingivalis W83, Nathan Maietta
Theses and Dissertations
Porphyromonas gingivalis, a gram-negative, anaerobic bacterium, is widely recognized as a causative agent for periodontal disease. Despite sequencing of the complete genome, no research exists examining gene regulation response in P. gingivalis to shifts in pH. Previous studies have shown that P. gingivalis is capable of surviving in the variety of micro- environmental niches found within the oral cavity, including basic and acidic pH conditions. However, the underlying mechanisms of this survival are not well understood. This study examined P. gingivalis by comparing bacteria shocked at three acidic to neutral pH conditions (5.5, 6.5 and 7.0) to bacteria vii shocked …
Variation In Sound Production Of The Blue Catfish, Ictalurus Furcatus., Zachary Ghahramani
Variation In Sound Production Of The Blue Catfish, Ictalurus Furcatus., Zachary Ghahramani
Theses and Dissertations
The blue catfish, Ictalurus furcatus, is an invasive species introduced to Virginia in 1974 and is the largest catfish in the United States. Like other Ictalurids, they are capable of producing disturbance calls via stridulation of the pectoral spine. These sounds can be made in air and water, and catfish can be preyed upon by both aerial and underwater predators. I characterized these putative distress calls by recording them in air and in the fish’s natural habitat. Sounds exhibited a wide variation in acoustic parameters relative to fish ontogeny: larger fish produced higher amplitude sounds with lower frequency bands. Sweep …
Evolutionary Relationships In Afro-Malagasy Schefflera (Araliaceae) Based On Nuclear And Plastid Markers, Morgan Gostel
Evolutionary Relationships In Afro-Malagasy Schefflera (Araliaceae) Based On Nuclear And Plastid Markers, Morgan Gostel
Theses and Dissertations
The genus Schefflera is the largest in Araliaceae, with approximately 900 species. Recent studies have shown that Schefflera is polyphyletic and represents no fewer than five distinct clades, each corresponding to a specific geographic region including Asia, continental Africa and Madagascar, Melanesia, the Neotropics, and a small clade distributed throughout several islands in the insular Pacific Ocean. The Afro-Malagasy clade contains nearly 50 species distributed throughout tropical, sub-Saharan Africa, Madagascar, the Comoros, and the Seychelles islands. Previous studies have suggested that this group is monophyletic, identifying two smaller subclades within Afro-Malagasy Schefflera corresponding roughly to informal groups identified as “Meiopanax” …
The Effects Of Hydrology And Vegetation On Microbial Community Structure And Soil Function In The Sediments Of Freshwater Wetlands, Christine Prasse
The Effects Of Hydrology And Vegetation On Microbial Community Structure And Soil Function In The Sediments Of Freshwater Wetlands, Christine Prasse
Theses and Dissertations
In wetland soils, hydrology is considered to be one of the primary factors shaping wetland function and microbial community structure, but plant-soil interactions are also important mechanisms affecting microbial nutrient transformations. The research presented here considered the interactive effect to describe how hydrology and the presence of plants alter the soil profile, the development of the bacterial community, and their associated functions. To achieve this goal, plots were established in three hydrologically-distinct regimes (Wet, Intermediate, and Dry) within a non-tidal freshwater wetland along the James River (Charles City County, Virginia). Inside each main plot, ten subplots were cleared of all …
Effects Of Alternative Prey As A Buffer To Predation Of Channel Catfish (Ictalurus Punctatus) By Largemouth Bass (Micropterus Salmoides), Shelley Nellis
Effects Of Alternative Prey As A Buffer To Predation Of Channel Catfish (Ictalurus Punctatus) By Largemouth Bass (Micropterus Salmoides), Shelley Nellis
Theses and Dissertations
Channel catfish have pectoral spines that lock to defend against gape-limited predators such as largemouth bass. Previous work indicated that spines increase survival of channel catfish exposed to bass but did not determine whether bass avoid catfish if less dangerous species are available. We presented bass with channel catfish and two alternatives, bluegill and goldfish, and compared order of ingestion, ingestion time, percent of successful strikes, and time spent chasing each prey species. We also presented the three species in a jar study that standardized position in the water column as well as in a net-pen study. The order of …
Genomic Analysis Of Nematode-Environment Interaction, Bishwo Adhikari
Genomic Analysis Of Nematode-Environment Interaction, Bishwo Adhikari
Theses and Dissertations
The natural environments of organisms present a multitude of biotic and abiotic challenges that require both short-term ecological and long-term evolutionary responses. Though most environmental response studies have focused on effects at the ecosystem, community and organismal levels, the ultimate controls of these responses are located in the genome of the organism. Soil nematodes are highly responsive to, and display a wide variety of responses to changing environmental conditions, making them ideal models for the study of organismal interactions with their environment. In an attempt to examine responses to environmental stress (desiccation and freezing), genomic level analyses of gene expression …
Factors Influencing The Abundance, Community Composition And Activity States Of Bacterioplankton From The Tidal Freshwater James River, Catherine Luria
Factors Influencing The Abundance, Community Composition And Activity States Of Bacterioplankton From The Tidal Freshwater James River, Catherine Luria
Theses and Dissertations
Aquatic bacteria respond to changing environmental conditions through a variety of mechanisms including changes in abundance, shifts in community composition and variable activity states. In the tidal-freshwater James River, variation in bacterial abundance was linked to nutrient availability and autochthonous production with highest bacterial densities associated with low-nutrient, high-chlorophyll a conditions. Laboratory experiments revealed that bacterial growth rates were nutrient limited at the low-nutrient site, while co-limitation (nutrients, glucose, light) was apparent at the high nutrient site. Despite large differences in abundance, community composition was similar based on TRFLP and 16S rDNA pyrosequencing. Community similarity was lower among rRNA libraries …
Investigation Of Potential Trapping Bias In Malaise Traps Due To Mesh Gauge, In Two Habitats, David Jensen Betts
Investigation Of Potential Trapping Bias In Malaise Traps Due To Mesh Gauge, In Two Habitats, David Jensen Betts
Theses and Dissertations
Malaise traps are a common tool for collecting insects used by many researchers. Although there have been variations in the models and materials used for Malaise traps, the potential for sampling bias due to mesh gague has been explored inadequately. This study compared coarse and fine mesh Townes model Malaise traps in two habitats on the Grand Staircase-Escalante National Monument. The two habitats next to the Lick Wash trailhead were defined by dominant vegetation type – sagebrush and grasses or Piñon-Juniper. We collected from three sites per habitat type, over three consecutive days in June in both 2006 and 2007. …
A Correlation Of Teacher Understanding Of The Nature Of Science (Nos) With Student Understanding, David G. Kent
A Correlation Of Teacher Understanding Of The Nature Of Science (Nos) With Student Understanding, David G. Kent
Theses and Dissertations
This is a study of how a teacher's understanding of the nature of science (NOS) correlates to student understanding of the nature of science. Participants are in semester long seventh grade science classes in a suburban school district. Seven strands of the nature of science were identified in the literature. Four strands were analyzed in this study. Teachers were ranked according to their understanding of the nature of science and compared to their corresponding students' average gain. There was no definitive pattern between the teacher's and corresponding students' gain. When broken down by strand, there still was no definitive pattern …
Landscape-Scale And Macrohabitat-Scale Variation In Growth And Survival Of Young June Sucker (Chasmistes Liorus) In Utah Lake, Joshua Daniel Kreitzer
Landscape-Scale And Macrohabitat-Scale Variation In Growth And Survival Of Young June Sucker (Chasmistes Liorus) In Utah Lake, Joshua Daniel Kreitzer
Theses and Dissertations
The spatial scales at which ecological phenomena are viewed constrain the results of interactions between species and their environments. In lake ecosystems, important dynamics have been identified at the landscape scale and the macrohabitat scale. To determine if landscape-scale effects and macrohabitat-scale effects are important in survival and growth of young June suckers, we compared variation among sites in Utah Lake. Large semi-permeable cages were used to house June suckers in situ at five sites representing landscape-scale variation and two sites representing macrohabitat-scale variation in Utah Lake. We compared survival and growth among sites and related it to resource availability …
Assessing Traditional Morphology- And Chemistry-Based Species Circumspections In Lichenized Ascomycetes: Character Evolution And Molecular Species Delimitation In Common Western North American Lichens, Steven Leavitt
Theses and Dissertations
Accurate species delimitation has critical implications for ecological and conservation studies; and for understanding factors driving diversification. However, a growing body of evidence indicates that morphology-based species circumspection in lichenized ascomycetes often fails to accurately represent the number of fungal species. The use of molecular data in lichen systematics provides an important alternative to traditional morphological characters for identifying natural groups and assessing evolutionary histories in challenging lichen taxa. In this work, I examined two common lichen-forming genera in western North America, Rhizoplaca and Xanthoparmelia, as models for investigating character evolution, species delimitation in morphologically and chemically diverse species, …
Utilization Of Phylogenetic Systematics, Molecular Evolution, And Comparative Transcriptomics To Address Aspects Of Nematode And Bacterial Evolution, Scott M. Peat
Theses and Dissertations
Both insect parasitic/entomopathogenic nematodes and plant parasitic nematodes are of great economic importance. Insect parasitic/entomopathogenic nematodes provide an environmentally safe and effective method to control numerous insect pests worldwide. Alternatively, plant parasitic nematodes cause billions of dollars in crop loss worldwide. Because of these impacts, it is important to understand how these nematodes evolve, and, in the case of entomopathogenic nematodes, how their bacterial symbionts evolve. This dissertation contains six chapters. Chapter one is a review of DNA markers and their use in the phylogenetic systematics of entomopathogenic and insect-parasitic nematodes as well as a review of phylogenetic, co-phylogenetic, and …
Infrageneric Relationships Within Collomia (Polemoniaceae), Eric Stewart Green
Infrageneric Relationships Within Collomia (Polemoniaceae), Eric Stewart Green
Theses and Dissertations
Traditional evolutionary models depict evolution as a bifurcating pattern with a single ancestor diverging to form two lineages. However, reticulate species resulting from hybridization and recombination have unique histories shared with two independent lineages, not one. Accounting for the genetic histories of reticulate species increases the power and ability to recover biologically meaningful relationships. The genus Collomia (Polemoniaceae) is used to explore issues of reticulation and the importance of accounting for gene histories in a phylogenetic analysis. The issue of reticulation within species trees is discussed with a multilabeled, network approach being explored to better represent the genus's evolutionary history. …
Investigation Of Science Education Attitudes In Alternative High School Settings, Sarah Jane Rogers
Investigation Of Science Education Attitudes In Alternative High School Settings, Sarah Jane Rogers
Theses and Dissertations
This study compared the attitudes of administrators, teachers and students in school settings for at-risk students. Students are considered at-risk if they are not academically successful. Teacher and student science education attitudes were analyzed by survey data and categorization of teaching practices. Additionally, data from classroom videotapes and teacher interviews was collected to support and triangulate survey data. Study participants were selected from two school settings for at-risk students 1) public alternative schools (PAS) and 2) private residential treatment centers (RTC). When the survey questions were analyzed by school type and teacher classification several differences were found between 1) teacher …
Student Content Knowledge Increases After Participation In A Hands-On Biotechnology Intervention, Amber L. Bigler
Student Content Knowledge Increases After Participation In A Hands-On Biotechnology Intervention, Amber L. Bigler
Theses and Dissertations
Hands-on learning is at the heart of science learning. This study examined increased changes of student content knowledge in biology, particularly biotechnology, after a hands-on biotechnology intervention was implemented into a secondary school. A traditional learning school was selected for a control. Both teachers had participated in a biotechnology professional development program called Project Crawfish. Students from both schools took the same assessment before and after their respective units (biotechnology intervention and genetics unit), and the classroom was the unit of analysis (n=5, n=6, respectively). The assessment was compared as a whole and then divided into five components, eight questions …
Long-Term Spatial And Temporal Variability Of Benthic Macroinvertebrate Communities: Implications For Bioassessment Of Lotic Systems, Eve O'Connor
Theses and Dissertations
The structure and composition of benthic macroinvertebrate communities can vary spatially and over time. Spatial and temporal variation along a stream has many implications for population and community dynamics, which may influence bioassessment programs. I examined variability in the benthic community of eight streams within the Polecat Creek, Virginia watershed. These streams vary in size from 1st to 4th order. The streams were sampled once every season for eleven years using standard bioassessment protocols. Macroinvertebrates were sampled from both sediment and submerged wood habitats at each site. The coefficient of variation (CV) was used to quantify among season, among year …
Assessing Scientific Inquiry: Teacher Beliefs And Practices, Adam James Mitchell
Assessing Scientific Inquiry: Teacher Beliefs And Practices, Adam James Mitchell
Theses and Dissertations
Science education reform movements have long urged the use of inquiry methods in all science instruction. More recently, standards and accountability reform efforts have emphasized measuring and improving student science achievement. Researchers have questioned the alignment and balance between these reforms (Lane, 2004; Yeh, 2001). This study addresses issues faced by secondary science teachers as they simultaneously meet the goals of these reform movements. Mixed methods were used to answer the questions: 1) Can a teacher's beliefs and practices regarding inquiry teaching methods be correlated with his/her assessment practices?; 2) What item types are most commonly employed by teachers that …
Mutation Of The Vesicular Monoamine Transporter-1 Gene Alters Its Protein Product, Abena Watson-Siriboe
Mutation Of The Vesicular Monoamine Transporter-1 Gene Alters Its Protein Product, Abena Watson-Siriboe
Theses and Dissertations
The vesicular monoamine transporter 1 (VMAT1) is essential for storage of monoamines, such as epinephrine and serotonin, in secretory vesicles of neuroendocrine cells. Recently the VMAT1 protein was detected in human and mouse brain, and mutations of the VMAT1 gene at single DNA nucleotides (single nucleotide polymorphisms or SNPs) were associated with schizophrenia. In this study, Chinese hamster ovarian cells were stably transfected with either human VMAT1 DNA (GenBank: #NM_003053.1 or DNA with the Thr4Pro SNP, which results in a threonine to proline change in amino acid number 4 of the VMAT1 protein. Western blot analysis revealed that cells with …
Spatial And Temporal Distribution Of Larval Fishes In A Large Tidal River., Harold Seelig
Spatial And Temporal Distribution Of Larval Fishes In A Large Tidal River., Harold Seelig
Theses and Dissertations
There are few published studies of larval fish assemblages from unregulated, tidal freshwater rivers. Patterns in the spatial and temporal distribution of larval fishes in the Mattaponi River were examined. Sampling took place on a weekly basis from February through August, 2006 and 2007. Larval fishes were categorized by taxa, reproductive guild, and residency guild. Group comparisons using multi-response permutation procedures (MRPP) indicated significant spatial and temporal differences in assemblage composition on multiple scales. Differences in assemblage composition were analyzed using non-metric multidimensional scaling (NMS). Interannual differences were attributable to anadromous and semi-migratory species. Seasonal differences were attributable to herrings, …
Expression & Purification Of Recombinant Plasmodium Falciparum Erythrocyte-Binding Ligands, Seward Joann Cofie
Expression & Purification Of Recombinant Plasmodium Falciparum Erythrocyte-Binding Ligands, Seward Joann Cofie
Theses and Dissertations
Plasmodium falciparum, the most virulent malarial parasite, is capable of invading all known human blood types. Erythrocyte invasion depends on specific parasite ligand and erythrocyte receptor interactions. These interactions are mediated by Region II of the P. falciparum erythrocyte binding ligands. Although invasion does not seem dependent upon a singular ligand, their individual contributions to the invasion process are yet to be explained. In this study, Region II of P. falciparum binding ligands BAEBL and JESEBL were transiently expressed as hexahistidyl recombinant proteins in COS-1 cells. Purification by column chromatography yielded 0.52 mg of BAEBL and 0.433 mg of JESEBL. …
Seasonal Patterns Of Nutrient Retention In A Restored Tidal Freshwater Stream Of The Mid-Atlantic Coastal Plain, Joseph Wood
Seasonal Patterns Of Nutrient Retention In A Restored Tidal Freshwater Stream Of The Mid-Atlantic Coastal Plain, Joseph Wood
Theses and Dissertations
Nutrient retention is governed by the interplay between physical processes that control the throughput of water and materials (i.e., water residence time), and by biological processes that govern transformation and uptake (e.g., microbial denitrification). A partial breach of the dam located on Kimages Creek (VA) re-established the historical (pre-1920) connection to the James River and provided a well-defined channel to gauge tidal exchange. We quantified tidal exchange as well as non-tidal (watershed) inputs on a monthly basis to assess Nitrogen (N) retention. Water and N fluxes were dominated by tidal exchange which was typically three times greater than inputs from …
Gene Flow And Dispersal Of The Caddisfly, Neothremma Alicia, In The Rocky Mountains Of Utah: A Multiscale Analysis, Xioben Jiang
Gene Flow And Dispersal Of The Caddisfly, Neothremma Alicia, In The Rocky Mountains Of Utah: A Multiscale Analysis, Xioben Jiang
Theses and Dissertations
We determined genetic variance and gene flow across multiple scales (reaches, tributaries, and catchments) to examine the dispersal ability of the caddisfly, Neothremma alicia in streams along the Wasatch Range in the Rocky Mountains of Utah. Neothremma alicia is one of the most abundant caddisflies in this region. We generated DNA sequence data (mitochondrial COI) from 34 reaches, nested in 15 tributaries distributed across 3 adjacent catchments. We identified 47 haplotypes from a total of 486 individuals. The most abundant haplotype (H1) was found at all sites/reaches and comprised 44% of the total number of individuals sequenced. The remaining rare …
Size-Structured Competition And Predation In Red-Eyed Treefrog Tadpoles, Christopher Asquith
Size-Structured Competition And Predation In Red-Eyed Treefrog Tadpoles, Christopher Asquith
Theses and Dissertations
Body size is important in determining the outcome of competition and predator-prey interactions. Size structure of a population (i.e. relative proportion of large and small conspecifics) may be particularly important in organisms with prolonged breeding periods and rapid growth where populations may have multiple cohorts at different stages of development competing for one resource. Both the consumptive and nonconsumptive effects of predators can also be size-dependent and can alter competitive interactions. Here we study the importance of size structure in the Neotropical leaf-breeding tree frog, Agalychnis callidryas. This species is a prolonged breeder such that multiple overlapping cohorts of differing …