Life Sciences Commons^™

Phospholipase D- And Phosphatidic Acid-Mediated Signaling In Plant Response To Abscisic Acid And Reactive Oxygen Species, Liang Guo

Dissertations

The Arabidopsis genome has 12 phospholipase D (PLD) genes that are classified into six types, PLDα, PLDβ, PLDγ, PLDδ, PLDε, and PLDζ, based on sequence similarities, domain structures, and biochemical properties. Phosphatidic acids (PA) produced by PLDs have been identified as important lipid signaling molecules in cell growth, development, and stress responses. This study was undertaken to determine the role of PLD and PA in plant response to abscisic acid (ABA) and reactive oxygen species (ROS). The lipid mediator PA was found to interact with sphingosine kinases (SPHKs) in Arabidopsis. Two unique SPHK cDNAs were cloned and expressed. Both SPHKs …

The Evolution Of Floral Symmetry Across The Plant Order Lamiales, Jinshun Zhong

Dissertations

Bilaterally symmetrical corollas have evolved independently numerous times from radially symmetrical ancestors and are thought to represent adaptation to specific pollinators. However, evolutionary losses of bilateral symmetry have occurred sporadically in different lineages. CYC2-like and RAD-like are genes needed for the normal development of bilateral symmetry in snapdragon corollas. However, exactly how changes in the floral symmetry patterning genes correlate with the origin and loss of floral bilateral remains poorly known. To address this question, a densely sampled phylogeny of CYC2-like genes across the order Lamiales was inferred and calibrated. The expression patterns of these genes in early diverging and …

Elucidating The Factors That Modulate The Distribution Of Avian Haemosporida Parasites Across A Community Of Hosts, Matthew Christopher Ikaika Medeiros

Dissertations

Parasites are heterogeneously distributed across host species, host populations, and host individuals within populations. A primary aim of infectious disease ecology seeks to uncover the factors that drive this heterogeneity. At a fundamental level, host infection is determined by exposure and susceptibility to a pathogen. My dissertation explores how evolutionary and ecological forces associated with these fundamental determinates of infection shape variation in parasite host breadth and host infection status. Here, I focus on a community of vector-borne avian Haemosporida parasites among suburban birds of Chicago, IL. These parasites exhibit strong variation in their distribution among available hosts, and provide …

Exploring The Local And Regional Effects Of Plant Diversity On Plant Herbivore Interactions, Diego Salazar

Dissertations

The study of biological diversity and its effects on ecosystem functioning and species interactions has always been a fundamental part of biology. The accelerating loss of species in conjunction with an increasing change in the natural environment has underlined the importance of the role that biodiversity has on the evolutionary and ecological dynamics of natural systems. In this dissertation I explore the effect of local and regional patterns of plant diversity in plant-herbivore interactions. Furthermore, this work goes beyond the classical concepts of taxonomical diversity and investigates the role of phylogenetic and chemical diversity on plant-herbivore interactions. In chapter one …

Connecting The Dots: Understanding Migration In The Context Of Other Periods Of The Annual Cycle, Kristina Lee Paxton

Dissertations

Migration is a fundamental characteristic of the life history of many organisms. Large-scale seasonal movements expose migratory species to an array of differing environmental conditions such that the ecology, behavior, and life history strategies of migratory species must balance selection pressures associated with each phase of the annual cycle. Therefore, scientists increasingly realize that to understand the ecology of a migratory species in any one phase of the annual cycle requires an understanding of how other phases may interact with and influence the period of interest. That said, following individuals throughout the year poses a serious challenge.

The focus of …

Middle Mississippi River Islands: Historical Distribution, Restoration Planning, And Biological Importance, Teresa Cecilia Allen

Dissertations

The Middle Mississippi River’s (MMR’s) hydrology and sedimentation patterns have been altered. These activities contribute to loss of backwaters, islands, secondary channels, and reduced biodiversity. The Fish and Wildlife Service included reasonable and prudent alternatives (RPAs) in its Biological Opinion for the Operation and Maintenance of the Nine-Foot Channel Navigation Project. These RPAs mandate dike notching and island building to increase habitat diversity. My first goal was to examine changes in the number and relative location of islands from 1797 to 2003. I found that the total number of islands increased, the number of central islands decreased, and the number …

Colonization History And Origin Of The Galapagos Flycatcher (Myiarchus Magnirostris) And Its Parasites, Eloisa Helena Reis Sari

Dissertations

The Galápagos flycatcher (Myiarchus magnirostris) is an endemic species to the Galápagos Islands, Ecuador, and is among the least studied Galápagos terrestrial birds. In this work I unveiled the origin and colonization history of the Galápagos flycatcher, and also the origin of the parasites that are currently found in/on this bird species. To determine the origin of the Galápagos flycatcher, I rebuilt the phylogeny of the Myiarchus genus using cytb and ND2, and applied a Bayesian approach to estimate its colonization time. I discovered that the closest living relative of the Galápagos flycatcher is Myiarchus tyrannulus (Brown-crested flycatcher) …

Science Fair: Is It Worth The Work? A Qualitative Study On Deaf Students' Perceptions And Experiences Regarding Science Fair In Primary And Secondary School, Vivian Lee Smith

Dissertations

Science fairs have a long history in American education. They play an important role for establishing inquiry-based experiences in a science classroom. Students may be more motivated to learn science content when they are allowed to choose their own science fair topics. The purpose of this study was to examine Deaf college students’ perceptions and experiences regarding science fair participation during primary and/or secondary school and determine the influence of science fair involvement on the development of language skills, writing skills, and higher order thinking skills as well as its impact on choice of a STEM major.

This study examined …

Role Of Msa In Immune Evasion, Persistence, And Protease Regulation In The Human Pathogenic Strains Of Staphylococcus Aureus, Maria Deepa Basco

Dissertations

Opportunistic pathogens like Staphylococcus aureus on entering the host can stay colonized at the foci of infection or evade the immune system to disseminate to other sites. In this study we investigated the regulatory influence of the modulator of sarA (msa) on immune evasion and host persistence, employing the hospital-acquired strain S. aureus UAMS-1 and community-acquired strain S. aureus USA300 LAC. In the murine sepsis model, mutation of the msa gene in LAC showed no change in dissemination of infection; however, in UAMS-1 a decrease in microbial load was observed in the lungs. Differential regulation by the msa gene was …

Population Demographics And Genetics Of Spix's Disk-Winged Bat: Insights Regarding Survival, Mate Choice, Gene Flow And Effective Population Size, Michael Buchalski

Dissertations

Simultaneous study of the demographics and genetics of populations are relatively rare within the literature, despite insights their combined use offers regarding the life history, ecology, and evolution of species. Here I take a comprehensive approach, using capture-recapture data, polymorphic microsatellite markers, and various modeling techniques to examine the demographics and genetics of multiple local populations of Spix’s disk-winged bat (Thyroptera tricolor) in southwestern Costa Rica. T. tricolor is a highly gregarious, neotropical bat species known to form kin-based social groups with high retention of offspring of both sexes. The implications of this highly unusual social structure for …

Discovery And Characterization Of A Tanapoxvirus Encoded Human Neuregulin Mimetic, David Jeng

Dissertations

Studies on large dsDNA viruses such as poxviruses have been helpful in identifying a number of viral and cellular growth factors that contribute to our broad understanding of virus-host interaction. Orthopoxviruses and leporipoxviruses are among the most studied viruses in this aspect. However, tanapoxvirus (TPV) a member of the genus Yatapoxvirus, still remains largely unexplored, as the only known hosts for this virus are humans and monkeys. Here, we describe the initial characterization of an EGF-like growth factor mimicking human neuregulin from TPV, expressed by the TPV-15L gene. Assays using a baculovirus expressed and tagged TPV-15L protein demonstrated the ability …

Investigating The Function Of The Mold Specific Gene M46, In The Pathogenic Dimorphic Fungus Histoplasma Capsulatum, Davida Lashaundra Crossley

Dissertations

Histoplasma capsulatum (Hc) is a dimorphic fungus that is the etiologic agent for the respiratory infection histoplasmosis. The fungus is found in the environment in contaminated soils of birds and bat excreta as a multi-cellular saprophytic mold. Once the soil is disturbed, spores are released and are inhaled into the lungs. In the lungs, the fungus converts to uni-cellular parasitic yeast (Maresca & Kobayashi, 1989). The conversion from mold to yeast is a requirement for pathogenesis. Previously, several mold specific genes have been isolated by our laboratory from a subtracted cDNA library. One such gene, is M46. M46 is a …

Characterization Of Whole Pine Tree Substrates For Adventitious Rooting Of Cuttings And Initial Growth Of Seedlings, Anthony Lynn Witcher

Dissertations

Processed whole pine (Pinus taeda L.) trees have been extensively evaluated to supplement peatmoss and pine bark usage in container substrates for greenhouse and nursery crop production. The suitability of whole pine tree (WPT) substrates for crop propagation has not been investigated. Demonstrating the versatility of WPT substrates is essential to expanding their commercial availability and use.

The objective of this work was to evaluate WPT substrates for stem cutting and seed propagation of ornamental crops, and to identify factors affecting root development. Stem cutting and seedling root development was evaluated in WPT and traditional (peatmoss and pine bark) …

Evaluation Of Human Fecal Pollution In Mississippi Coastal And Creek Waters Using Library Independent Markers, Christopher John Flood

Dissertations

The objective of this study was to determine whether statistically valid correlations could be elucidated between standard indicator bacteria (enterococci and fecal coliforms) from coastal creek and marine samples and the presence of four library independent molecular markers that are human or sewage specific. Eight hundred and nineteen samples were collected between August 2007 and July 2010 to determine enterococcal and fecal coliform counts and the presence of genetic markers for sewage indicator organisms Methanobrevibacter smithii, human specific Bacteroides sp., Bacteroides thetaiotaomicron, and Fecalibacterium sp. During the course of this study environmental parameters were measured and statistically analyzed to determine …

Accessing Learning In The Adult Zebrafish With A Novel Associative Learning Task, David Joseph Jouandot Ii

Dissertations

The zebrafish (Danio rerio) is accepted in the developmental and genomic communities as a model organism. However, the capacity for the zebrafish as a behavioral model has yet to be fully acknowledged. The research presented provides evidence validating the novel task, aids in gaining a better understanding of the learning processes, and identifies individual differences. The novel associative learning task differs from any present well established behavioral model and lends itself to future development. The task provides the zebrafish community with a high output behavioral task which is readily replicated and allows one researcher to test between eight …

Effects Of Food Dispersion On Dominance Related Behaviors In Garnett's Bushbaby (Otolemur Garnettii)?, Kyle Daniel Edens

Dissertations

Socio-ecological theorists tie primate social structure diversity to variations in habitats within which primate species reside. This premise permits laboratory researchers to investigate specific factors that influence or relate to social structure formation and maintenance. The focus of the current investigation was three fold. We first aimed to determine the relationships between traditional and non-traditional behavioral measures of dominance, then evidence for dominance hierarchy formation was examined, and various hypotheses were tested to discern if adjustments in the foraging context altered social behaviors in Garnett’s bushbaby (Otolemur garnettii). It was determined that animals likely to displace conspecifics were …

Interrelationships Between Testosterone, Aggression, And Parental Care Of A Temperate-Zone, Resident Songbird, The Northern Cardinal (Cardinalis Cardinalis), Margaret Susan Devries

Dissertations

Interrelationships among testosterone (T), aggression, and parental care have received much investigative attention. Within birds, many studies have focused on examining such relationships using species characterized by relatively brief periods of territoriality and breeding. Few have investigated links between circulating T and reproductive behavior in birds that are year-round territorial residents and have lengthy breeding seasons, such as the Northern Cardinal (Cardinalis cardinalis). The following six chapters report and discuss findings from this dissertation’s examination of aspects of T production and potential interconnections with circulating T, aggression, and parental care in male and female cardinals. This work suggests …

Community Metrics And Trophic Dynamics In Tidal Creeks In An Anthropogenically Fragmented, Coastal Landscape, Michael Robert Lowe

Dissertations

Salt marsh landscapes are among the most anthropogenically altered ecosystems in the world. Urbanization (i.e., accumulation of impervious cover and man made structrues) of the coastal landscape can disrupt the delivery of numerous ecosystem services. Among the many services provided by salt marsh habitats, they serves as the primary habitats for distinct macroinfauna (i.e., benthic and epibenthic macrofauna) and nekton (i.e., fish and decapod crustaceans) assemblages. In this dissertation, I used a number of metrics to test the overarching hypothesis that coastal urbanization has negative consequences for salt marsh faunal assemblages. Chapter I uses a landscape ecology approach to show …

A Bird In The Binoculars: Understanding Birdwatchers' Potential To Contribute To Sustainable Development And Biological Conservation, Sheri Lynn Glowinski

Dissertations

The three studies comprising this research drew from local economic development and environmental sociology to understand aspects of human dynamics that influence the conservation of birds. Using survey data collected from birdwatchers visiting coastal Alabama, the first study examined the local economic impact of birdwatching tourism and the factors that participants deemed important with respect to their recreation. Birdwatchers spent $103,305 during the four month study period. The total annual economic impact of this recreation on the area was estimated at $937,470, producing a multiplier of 1.48 and the equivalent of 20.3 full time jobs. Infrastructural variables (parking, bathrooms, site …

Diversification And Coexistence In The Madagascar Olive (Noronhia, Oleaceae), Cynthia Hong-Wa

Dissertations

The long-isolated island of Madagascar provides a suitable setting for studying species diversification, with most groups of organisms there both radiating and showing a high level of endemism. Noronhia is one of these groups and represents the most successful radiation of the olive family (Oleaceae) in Madagascar, with ca. 80 species. In this study, using plastid and nuclear DNA sequences obtained from a comprehensive sampling both within Noronhia and the family, I show that Noronhia, together with Indian Ocean species of Chionanthus, form a monophyletic clade sister to African Chionanthus. The diversification of Noronhia followed a likely Cenozoic dispersal from …

Astrocytes Modulate Microglial Phenotype And Dendritic Cell-Like Properties, Nischal K. Padala

Dissertations

Microglia are the resident immune cells of the CNS. In the healthy CNS, they express negligible levels of MHC II molecules as well as co-stimulatory molecules CD40, CD80 and CD86 necessary for antigen presentation to and activation of T cells. Co-stimulatory molecule expression can be induced in isolated microglia in vitro by sequential treatment with granulocyte monocyte colony-stimulating factor (GM-CSF) followed by lipopolysaccharide (LPS). Upon such treatment, they become mature dendritic cells (DCs), capable of activating T cells. However, microglia are not isolated in life, but rather exist in an environment enriched by other cells, notably astrocytes.

Therefore, to determine …