Student Research Projects - 2002-2003
A Comparative Survey of Chemosensor Structure and Arrangement on Crayfish Antennules: Does Flow Environment Predict Structure? >
Advisor: Kristina Mead
Crayfish flick their antennules in order to sample their olfactory environment. This action distributes chemical information to chemoreceptive aesthetascs on the outer filament of the antennule. Because flow environment affects the structure of odor plumes, I hypothesized that species from different flow environments would have different numbers and arrangements of chemosensors along their antennule filaments. I hypothesized that those structures might vary as a function of position along the antennule filament. This study utilizes both light and scanning electron microscopy to measure a variety of parameters that describe aesthetasc arrangement and structure in seven species of crayfish. I found that some parameters (aesthetasc size and arrangement) varied as a function of flow environment, and that some parameters (aesthetasc distribution and arrangement) varied as a function of position.
Repeatability of Microhabitat Selection and Activity levels of Bullfrog Tadpoles (Rana catesbeiana) >
Advisor: Geoff Smith
I investigated the repeatability of individual bullfrog (Rana catesbeiana) tadpoles for microhabitat preference and activity levels. Tadpoles showed a preference for habitats that were vegetated and that had large rocks as substrate. Tadpoles also preferred deeper water. Individual tadpoles did not show repeatability in habitat preference or activity levels. There was no correlation between activity levels and habitats, showing that an individual’s behavior in one environment did not necessarily reflect how they behaved in another.
An Examination of the Bird Communities at Seven Sites Within Licking County >
Advisor: Tom Schultz
As urban sprawl spreads into Licking County, both forest and field bird habitats are being reduced. The purpose of this study was to compare differences in components of bird diversity and microhabitats between 7 sites within Licking County differing in forest/field areas and area dimensions, surveyed over the spring/summer of 2002. Between the sites, Shannon indices showed that Alrutz, Infirmary Mound, and Marie Hickey each differed significantly in bird diversity from 3 of the other sites, while Lobdell and Taft Reserve both differed significantly in bird diversity from 4 of the other sites. Norpell/Taylor-Ochs differed significantly from all other sites. Also, regression analyses were performed between Shannon indices of summer residents and site microhabitat area as well as habitat heterogeneity. A significant positive relationship occurred between the site Shannon indices and amount of old field (km2), but this result was called into question. Conservation strategies recommended include allowing heterogenous blocks of field and forest to grow, opposed to thin, finger-like projections.
Interactions with Nrt: A Yeast Two-Hybrid Assay >
Advisor: Eric Liebl
Neurotactin (Nrt) is a transmembrane protein expressed in the developing central nervous system of Drosophila embryos. It is believed to play a role in axon pathfinding. Yeast two-hybrid is a system that allows for the discovery of novel protein-protein interactions. A yeast two-hybrid assay, performed on a cDNA library using the intracellular portion of Nrt as bait, revealed two hits encoding portions of the protein filamin, which is known to bundle actin in vivo. A pulldown experiment using GST conjugated to the intracellular domain of Nrt and in vitro transcribed and translated cDNAs was performed. Only one of the two filamin cDNAs appeared to be properly transcribed and translated and it was not observed to be pulled down by GST-Nrt. Future experiments will likely focus on optimizing the in vitro transcription and translation and the pull down conditions along with continuing screens of the cDNA library.
The Effects of Exposure to Organic Wastewater Contaminants on African Clawed Frog (Xenopus laevis) and Northern Leopard Frog (Rana pipiens) Tadpoles >
Advisor: Geoff Smith
Recent studies have detected organic wastewater contaminants (OWCs) in U.S. surface and groundwaters. Despite the widespread presence of OWCs, little is known about their effects on aquatic organisms, especially at ecologically relevant levels. In this study, African clawed frog (Xenopus laevis) and northern leopard frog (Rana pipiens) tadpoles were chronically exposed to three OWCs: acetaminophen, caffeine, and triclosan. Effects on behavior, survivorship, and growth were determined. Xenopus laevis showed decreased activity with acetaminophen exposure, and decreased activity and growth with triclosan exposure. Rana pipiens showed decreased survivorship, growth, activity, and startle response to triclosan. Rana pipiens also showed affected activity and growth with caffeine exposure, and affected startle response with acetaminophen exposure. There were interactive effects of caffeine and acetaminophen and of triclosan and acetaminophen. These results show that the levels of OWCs present in aquatic ecosystems could have a significant impact on the fitness of amphibians and other species.
A Rapid Ecological Assessment of the Hill Wetland Reserve in Granville, Ohio with an Emphasis on Breeding Amphibian Habitat >
Advisor: Tom Schultz
Wetland habitats are vital to the existence of many organisms, but unfortunately human activities have a negative impact on their health causing their numbers to rapidly decline. The focus of this study was on the Hill Wetland Reserve in Granville, Ohio that was donated in 1996 to a local conservation organization, the Licking Land Trust. The rapid ecological assessment was used to gain information about the history of the land, the important hydrogeologic features, the vegetation that can be found, as well as the amphibians that use the wetland for breeding in the spring. Although this study was preliminary, it was determined that the Hill Wetland Reserve and the surrounding uplands were important to breeding amphibians. In the future monitoring and management techniques should be researched and implemented in order to conserve this habitat that provides important functions to the local community and the environment.
Cloning Methionine Aminopeptidase from the Extreme Halophile Haloarcula marismortui >
Advisor: Charles Sokolik
Haloarcula marismortui is an archaebacteria that thrives in a 6 M saline environment. To compensate for the osmotic pressure from its environment, H. marismortui accumulates K+ and other ions intracellularly, which necessitates the adaptation of its proteins to function in high salt environments. Methionine aminopeptidase (MAP), a ubiquitous protein responsible for cleaving the initial methionine of many proteins as a common post-translational modification, will be cloned from H. marismortui and its adaptations to a high salt environment investigated. The gene for MAP from H. marismortui (HmMAP) will be cloned using the polymerase chain reaction (PCR). We present here the appropriate primers and the optimal conditions for the PCR amplification of HmMAP, as well as the sequence of a successfully cloned segment of the gene. The entire HmMAP gene could be located by using this segment of the gene as a probe in Southern hybridizations.
Immunolocalization of Focal Adhesion Kinase in Nerve Growth Factor-Induced PC12-wt2 Neurogenesis >
Advisor: Cathie Smith
Focal Adhesion Kinase (FAK), a 125 kDa non-receptor, protein tyrosine kinase, is known to be important in intracellular signaling cascades relating to cell adhesion and migration. Although FAK has been studied at the beginning of neurogenesis and short-term focal adhesion turnover, research into FAK’s role in adhesion during long-term neurogenesis has been limited. PC12 cells, a rat pheochromocytoma cell line, provide an ideal system to study FAK, focal adhesions and neurogenesis. PC12 cells can be induced to differentiate into a neuron-like cell and project neurite extensions from the cell body within twenty-four hours of stimulation with Nerve Growth Factor (NGF). The goal of this study was to investigate the localization of FAK and phosphorylated or kinase activated FAK in one and five day NGF stimulated PC12-wt2 cells. If FAK is essential for adhesion and migration, then localized areas known as focal adhesions and point contacts should be discernable through fluorescent immunolocalization. This research shows that sites of FAK and phosphorylated/activated FAK are discernable throughout the cytoplasm, but lacking in the nucleus, confirming that it FAK is a nonnuclear protein. Additionally, FAK and phosphorylated FAK were present in the growth cones (tips of projecting neurites) in day one and day five NGF-stimulated PC12-wt2 cells and throughout the neurites of day five NGF-stimulated PC12-wt2 cells. These localization points could indicate points of attachment between the cell and extracellular matrix as well as important areas involved in neurite migration.
Identification of Amalgam and Neurotactin as Dominant Enhancers of the Abl Mutant Phenotype >
Advisor: Eric Liebl
Axon outgrowth and directional pathfinding are processes that are vital to central nervous system (CNS) development. The Drosophila model system is useful to study highly conserved signaling pathways that lead to proper axon pathfinding. The gene for the Abelson tyrosine kinase (Abl) has been shown to be vital to such pathways. Many dosage-sensitive, genetic modifiers of the Abl mutant phenotype have been identified, thereby providing clues toward the mechanisms of the Abl-mediated signaling network and proteins involved in initiating and propagating signaling through Abl. Two genes that demonstrate novel genetic interactions with Abl encode the secreted adhesion molecule Amalgam (Ama) and its receptor Neurotactin (Nrt). In this study, mutational analyses of these loci have implicated this adhesion complex in the Abl network. Characterization of mutations in these proteins has provided insight into mechanisms of Ama-Nrt-mediated adhesion. We have also called into question the role of the disabled (dab) gene in neural development by proving that mutant alleles previously thought to be at this locus are actually at the nrt locus.
Developing an Understanding of Factors Influencing Sense of Pace in In-Season Female Collegiate Cross Country Runners >
Advisor: Kristina Mead and Pan Fanaritis
The belief that the ability to run at a consistent pace over a long distance will improve running performance was the basis for this research. Influences on the ability to run at certain intensities, judge the pace at which one is running, and consistently run at the same pace were investigated. The use of internal and external feedback systems to gauge the effort level of exercise was explored in two ways: a review of the literature and testing the ability of runners to achieve a goal time over a variety of conditions. Subjects consistently attained times that were significantly different from the goal time, indicating that these conditions may influence the ability to judge/maintain pace. General trends revealed by this project may direct further research.
Influence on Size at Maturity in Draba verna L. (Brassicaceae) in Granville, OH >
Advisor: Julie Mulory and Paul Andreadis
Draba verna L. is a winter annual found in Granville, Ohio. Despite genetic homogeneity at various localities these plants show size variation at reproductive maturity. The variables studied were mother size, number of seeds collected per mother, seed size, and first seedling emergence date. Competition was eliminated as a factor in the experimental design. Statistical analysis was done to compare the variables and determine if any correlations were present. The number of seeds collected was positively correlated with the size of the mother. No correlation existed between mother size and average seed size or between mother size and the date of first seedling emergence. Smaller mothers showed greater variance in emergence time. Being a small mother proved to be disadvantageous. The size variation in adult D. verna is still puzzling; however, these results can be used as a starting point for future research on D. verna.