Below is a list of Honors Theses that have been successfully completed by Biology Majors at the University of Scranton (or students who worked with Biology faculty) in recent years. Click on the thesis title links to view the thesis abstract (if available). The faculty preceptors are indicated in parentheses. Complete bound copies of each thesis are available in the library for your reference.
Maria Shiptoski - The Role of NMDA Mediated Excitotoxicity in Stroke (Waldeck)
Michael Aughenbaugh - "Analysis of the Effects of Iron Pollution on E. coli Growth " (Cadigan)
Mae Lynn Chan- Effects of burial time and puncture
location on the breaking strength of acorns (Voltzow)
Kristen Fenocchi - Effects of peroxynitrite on myelin
basic protein expression and traffic in cultured embryonic chick brain
(Biology/Neuroscience double major)
Jamie Hood - Immunology of Celiac Disease (Cadigan)
Kelly Johnson - Sweet Sorghum as a Potential Biofuel: Determination of Biomass, Potential Sugar Production, and the Relative Ethanol Yield Upon Primary Fermentation of Hydroponically Grown Sorghum (Hardisky)
Brandon Kujawski - The effect of temperature on the
regenerative capacity of neurons in the goldfish spinal cord (Waldeck)
Danielle Torres - The Effects of Anthropogenic Carbon Dioxide on the Sea Anemone, Aiptasia pallida (Voltzow)
Alesia Walsh - A model of indirect nerve damage: implications for trigeminal nerve degradation associated with exposure to stressors associated with oral trauma and disease (Gomez)
(Biology/Neuroscience double major)
Guiseppe Bongiorno - Facial Bumps of Phyllostomid Bats: LM Characterization (Kwiecinski)
Ishita Dalal - PCR Detection of Burkholderia cenocepacia (Sulzinski)
Mary Grace Rizzo - Bisphosphonate related osteonecrosis of the jaw: A closer look at some of the current research findings and an elaboration of recommended treatment with an emphasis on conservative treatment (Sulzinski)
Allison Greco - Hypoxic and hyperoxic stress-induced hypertrophy in cultured chick fetal cardiac myocytes (Gomez)
Denise Hardisky - An investigation of the use and fitness consequences of using shrub-land habitats by Gray Catbirds migrating through Northeastern Pennsylvania (Smith)
Eamon Filan - Genetics and Sex Selection (McDermott)
David Fryzel - The Efficacy of Continuous Passive Motion Device Post Total Knee Arthroplasty (Waldeck)
Ashley Gonsky - Biofilm Communities in Endodontic Infection and Treatment (Sulzinski)
Kaci Haines - Investigating the Effects of Embryonic Sensory Experience on Fetal Development (Gomez)
Karolyn Holody - Comparative study of the gills of three species in the gastropod family Trochidae (Voltzow)
(Biology & Spanish major)
John Miller - Developing a Mechanical Model of the Cardiovascular System (Sweeney)
Sarah Muth - Localized Areas of the Goldfish Telencephalon That Modulate the Startle Response (Waldeck)
Cassandra Zagorski - Investigating the Long-Term Cellular Effects of Hyperglycemia on PKC Expression in Developing Chick Embryos (Gomez)
Sharon Secola - The Role of the Optic Tectum in the Startle Response of Goldfish (Waldeck)
(Biology & Spanish major)
Mary Ann Smith - Impacts of acid mine drainage (Cadigan/Hardisky)
Amanda Celii - The development of in ovo odor sensitivity in chicks (Gomez)
(Biology/Neuroscience double major)
Lyndsey Collins - The Drive to Survive: Inhibition of the Acoustic Startle Response in Carassius auratus (Waldeck)
James Costanzo - The Na+/Ca2+ exchanger is not the primary mechanism for odorant-elicited calcium decreases in cultured human olfactory cells - (Gomez)
Sol de Jesus - Behavioral observation of odor imprinting in chicks (Gomez)
Diana Drogalis - Awareness of Diabetes and Dental Complications: A Survey of Oral Health Promotion (Hardisky)
Pollyanna Fino - The molecular biology of non small cell lung cancer (Sulzinski)
Erin Miller - The Effect of Complete Ablation of the Telencephalon on the C-start Method of Feeding in Goldfish (Waldeck)
Jessica Phillippy - An Examination of Immune Function in Gray Catbirds Relative to Time of Arrival and Condition Upon Arrival at Breeding Grounds in Northeastern Pennsylvania (Smith)
Renee Szumski - Facilitation of axon regeneration (Waldeck)
Kristin Riley - Utero-ovarian resistance arteries contribute significantly to estrous cycle day dependent control of ovarian blood flow (Sweeney)
Stephanie Yazinski - Structural and functional maturation of olfactory receptor neurons (Gomez)
(Biochemistry & Biomath major, SJLA)
Jessica Lewis - The Biblical Healing Tradition and Modern Medicine (Pinches)
Lisa Malys - Auditory ecology of Northeastern Pennsylvania bats (Kwiecinski)
Melissa Reynolds - Role of the Telencephalon in the Goldfish Avoidance Response (Waldeck)
George El Bayadi - Refugia Indicate the Effects of Overbrowsing on the Composition of Understory Plants in a Northern Hardwood Forest (Townsend)
William Jesse Kayal - Self-Incompatibility in Arabidopsis lyrata: Isolation of Lambda Genomic Clones from the S Locus (Dwyer)
Corey Tabit - Proximate Constituents of Milk from Two Phyllostomid Bats (Kwiecinski)
Eric Wirkus - Odor Signal Detection in Avian Olfactory Neurons (Gomez)
Joanne A. Bishara - Screening of SSH-Selected DNA Sequences Unique to the Bacillus anthracis chromosome by PCR Amplification (Dwyer)
Eileen L. Blake - The Effect of High Deer Density on the Forest Understory (Townsend)
Jessica L. Carpenter - The effect of Typha latifolia (Cattails) and soil hydration upon methane efflux from marsh sediments (Hardisky)
Susan E. Dulka - The Effects of Typha latifolia (common cattail) and Soil Hydration on Respiration from Wetland Soil (Hardisky)
Michelle Falzone - Milk Mineral and Nitrogen Levels and Their Neonatal Accretion in Two Neotropical Plant-Visiting Bats (Kwiecinski)
Paul M. Rutkowski - An Initial Survey of The Effect of Acid Mine Drainage on Bioproductivity in the Lackawanna River (Cadigan)
Thesis abstracts appear below
Investigating the Effects of Embryonic Sensory Experience on Fetal Development
The objective was to examine the timecourse of chick olfactory system development using anatomical and behavioral techniques. Chick eggs take 21 days to develop and hatch. The olfactory system begins to develop at embryonic day eight (E8) and is functional at hatching, but the timecourse of this development is poorly understood. This timeline of development can be examined both at the cellular level by, observing protein expression patterns in the chick brain, and at the behavioral level, by studying chick odor imprinting. Two different odorants, amyl acetate and phenylethyl alcohol were added at varying timepoints to developing chicks in ovo. The expression pattern of the immediate early gene cFos, resulting from the odorant’s stimulation, was visualized to determine if the neural circuitry in the chick brain is developed in the embryo. This development was also measured behaviorally: when exposed to odors in ovo, newly-hatched chicks will potentially be attracted to these familiar odors. Odor imprinting in newborn chicks exposed to the two test odorants was studied using a Y-maze to determine if a preference for familiar odorants exists. The results suggest that amyl acetate results in maximal cFos expression beginning around E16 and increasing until hatching, but that phenylethyl alcohol exposure causes only baseline activity, similar to chicks exposed to no odor. This neuronal activity is not necessarily indicative of imprinting, as conflicting and inconsistent behavioral results illustrate.
Hypoxic and hyperoxic stress-induced hypertrophy in cultured chick fetal cardiac myocytes
The adult heart responds to increased contraction demands by hypertrophy, or enlargement, of cardiac myocytes. Hypertrophy can occur in response to both physiological factors (generally resulting in hyperoxic conditions and cause adaptation), or pathological factors (typically resulting in hypoxic conditions which cause heart failure). The difference in the outcomes produced by pathologically- versus physiologically- induced hypertrophy suggests that the cellular signaling pathways or conditions of myocytes may be different at the cellular level. The structural and functional changes in myocytes resulting from hyperoxia (simulated using hydrogen peroxide) and hypoxia (using oxygen deprivation) were tested on fetal chick cardiac myocytes grown in vitro. Isolated myocytes grown for 2 days were exposed to stressors, then grown for an additional 1 to 6 days. Structural changes were measured using immunostaining for sarcomeric actin or MyoD (a transcription factor that regulates myosin production). Functional changes were assessed using immunostaining for calcium-calmodulin kinase (CaMK) or by measuring intracellular calcium fluxes using live cell fluorescence imaging. Hypo- or hyperoxic stress resulted in an up-regulation of actin and MyoD expression, indicating hypertrophy. However, these structural rearrangements occurring are not in themselves detrimental. Similarly, voltage-gated channels and the regulation of myosin activation by CaMK are unchanged by hyper- or hypoxic conditions. The changes in transcription regulation causing such structural changes may affect components of ligand-activated signaling pathways, and subsequent stimulations of myoctes may result in a depletion of calcium stores in the sarcoplasmic reticulum. Although this study does not indicate whether the observed changes to signaling cascades or calcium stores are beneficial or detrimental, it does suggest that changes in signaling pathways, rather than structural organization, may cause the fatal outcomes associated with pathologically-induced hypertrophy.
Mary Kate Hoffman
The role of plasma membrane calcium channels in odorant-elicited calcium signaling of cultured human olfactory cells
Calcium, a ubiquitous intracellular messenger, drives depolarization reactions and generates action potentials in olfactory receptor neurons (ORNs) in a manner similar to those in other neurons. ORNs respond to odorants with changes in intracellular calcium concentration ([Ca2+]i). Odorant-elicited calcium fluxes in human olfactory cultured cells (HOCCs) display similar characteristics to those found in mature human olfactory neurons, so HOCCs will be tested in this experiment. Characterization of the mechanism behind calcium effluxes is important, since healthy and diseased human ORNs employ odorant-elicited [Ca2+]i effluxes. The plasma membrane calcium ATP-ase (PMCA) is a protein in the plasma membrane of ORNs known to decrease [Ca2+]i following odorant stimulation. The understanding of the mechanism behind [Ca2+]i decreases, particularly PMCA function, may further elucidate studies on physiology of olfaction, neurogenesis, and neurodevelopmental diseases. Cell responses to odorants were recorded with live cell imaging techniques and the PMCA expression was studied with immunocytochemistry. Sodium orthovanadate reversibly inhibited the PMCA in order to abolish odorant-elicited [Ca2+]i fluxes in cells. The same cells responded to two different odorants, suggesting the possibility of dual second messenger systems in HOCCs. This study also suggests the differential effect of the odorants on the PMCA; odorant solutions, which trigger specific second messengers, cAMP and IP3, affect PMCA function.
Comparative study of the gills of three species in the gastropod family Trochidae
Members of the gastropod family Trochidae utilize two main forms of feeding: grazing and suspension feeding. Grazing is the common form of feeding while suspension feeding is relatively rare. While there are other species in the family Trochidae that graze and suspension feed, I only looked at three species in order to compare the two mechanisms used. Members of the species Lirularia succincta use suspension feeding while those of Calliostoma ligatum and Margarites pupillus are grazers. This study examined the morphology of the gills of L. succincta in comparison with C. ligatum and M. pupillus. I used dissection and scanning electron microscopy to observe the anatomy and morphology of the mantle cavity and its organs. Suspension feeding gastropods have gills composed of thin, elongated lamellae (individual leaflets), while grazing gastropods have triangular-shaped lamellae. In addition to the gill, there exist other differences between L. succincta and the grazers of the trochid family. Ciliated grooves on the right-side of the neck and body of L. succincta provided a key difference in the morphology that aids suspension feeding. Oriented from the gill to the bottom of the neck flap, these structures create a pathway for the mucous cord to travel and reach the mouth and radula. Individuals of L. succincta suspension feed in a manner similar to gastropods of the family Calyptraeidae, in which all members are suspension feeders. The gills of the specimens of L. succincta more closely resemble those of Crepidula fornicata, a member of the family Calyptraeidae. These comparisons allowed me to discover feeding structures distinctive to the suspension feeding L. succincta, and helped me to understand the different mode of feeding used by L. succincta
Localized Areas of the Goldfish Telencephalon That Modulate the Startle Response
In humans, the limbic system is believed to play a role in fear conditioning. Previous studies have suggested that the goldfish telencephalon, a more primitive structure, may perform a similar function in goldfish (Portavella et al 2003). Other studies have shown that the telencephalon does play a role in modulating the startle response in goldfish (Collins and Waldeck 2006). The current study investigated the different areas within the telencephalon that may modulate the acoustic startle response, mediated by the Mauthner cell in Carassius auratus. The avoidance response was tested for three consecutive days prior to surgery. On the fourth day, fish were anesthetized and either the right or left medial or lateral portions of the telencephalon were removed. Following this removal, fish were re-tested for three more consecutive days. Avoidance response was scored on a scale from zero to three, with three indicating a complete C-start response and zero representing no response. Following the surgical lesions of the right side of the telencephalon, regardless of being in the medial or lateral locations, the fish show a decreased or, in some cases, completely extinguished, C-start movement in response to vibratory stimuli. This suggests that the right lobe of the telencephalon may modulate the response, possibly in some way priming the Mauthner cell. Control fish had normal avoidance responses.
Investigating the Long-Term Cellular Effects of Hyperglycemia on PKC Expression in Developing Chick Embryos
This research project examines the cellular effects of hyperglycemia in chick astrocytes and endothelial cells. Diabetes is a debilitating condition that affects not only maternal health but potentially fetal development and well-being as well. Among the many cellular effects of diabetes is the dysfunctional expression and/or regulation of cellular signaling molecules such as protein kinase C (PKC). This research project therefore tests this notion by artificially inducing hyperglycemia in chick embryos, and determining the effects on PKC expression in embryonic astrocytes and endothelial cells. Hyperglycemia appeared to induce acute, but not chronic, effects in astrocytes but not in endothelial cells. Results from this study will hopefully enable a better understanding of the mechanisms underlying various conditions experienced by diabetics that are caused primarily by hyperglycemia. This may have implications regarding the cellular effects of hyperglycemia on the progeny of diabetic mothers.
The development of in ovo odor sensitivity in chicks
The chick olfactory system in the embryo is known to attain function prior to hatching; the periphery neurons develop function as early as embryonic day 13 (E13). To determine the specificity and critical period for development of odor sensitivity in chick olfactory central nervous system, the different patterns of activation of the immediate early gene cFos in the olfactory bulb were determined. Chick embryos were exposed to amyl acetate, phenylethyl alcohol, or no odor for 3 day periods from E14 through E20; cFos immunoreactivity was examined to determine olfactory bulb activation as a result of odorant exposure. Staining patterns for each animal exposed to amyl acetate versus phenylethyl alcohol and those from chicks exposed to the same odorant over different time periods were compared. cFos staining patterns suggest differences in odorant-elicited bulbar activation occur from E15 through E18 suggesting that the critical period for the development of odor sensitivity occurs at this time. This highlights the importance of the sensory environment in shaping the developmental pathways of the olfactory system.
The Na+/Ca2+ exchanger is not the primary mechanism for odorant-elicited calcium decreases in cultured human olfactory cells
Olfactory receptor neurons (ORNs) respond to odorants with changes in intracellular calcium concentrations ([Ca2+]). In human ORNs, about a fourth of these responses are decreases in [Ca2+]; thus this type of response represents a large portion of the input into the olfactory bulb, yet the mechanism behind this type of response is unknown. The involvement of the Na+/Ca2+ exchanger (NCX) was investigated in this system using human olfactory cultured cells (HOCCs) due to their availability, ease of use, and because they demonstrate structural and functional characteristics similar to those found in acutely isolated human ORNs. Cells were grown on 6-well plates and tested with odorants in the presence or absence of extracellular Na+; responses were measured using calcium-imaging techniques. The cells were subsequently fixed and tested with immunocytochemistry using antibodies against the NCX. This study suggests that the NCX is present in HOCCs but is not the primary mechanism for mediating odorant-elicited [Ca2+] decreases. An understanding of the mechanism responsible for generating [Ca2+] changes may have important implications for the study of the physiology of olfaction, neural development, and neurodegenerative diseases.
Sol de Jesus
Behavioral observation of odor imprinting in chicks
The chick olfactory system begins development at embryonic day 8 (E8) and is known to be functional by E15. Studies have shown that chick embryos exposed to odorants in ovo can recognize these odorants after hatching, suggesting that the olfactory system perceives and decodes odor stimuli during development. This in ovo experience, imprinting, may shape the animals’ behavior upon hatching, presumably to make them better adapted to their immediate surroundings. Much like visual imprinting, “odor imprinting” may impart a survival advantage to newborn chicks. The present study attempts to investigate when odor imprinting occurs during embryonic development. The incubated chicks were exposed to single odorant for 3-day periods from E12 and E21. Upon hatching and two days after birth, chicks were tested for their preference for “familiar” versus “unfamiliar” odorants using a T-maze. Unlike previous studies, both a novel odorant, phenylethyl alcohol and amyl acetate, were introduced to determine if exposure to odors in ovo early on could induce behavioral preferences in newborn chicks and an attempt to quantify the timeline of the development of this chemical sensitivity to imprinting were conducted. Incubated chick eggs were exposed to single odorant for 3-day period intervals from E12 and E21. Result showed that although imprinting did not occur odor recognition of amyl acetate did take place. The chicks did not detect Phenylethyl alcohol suggesting avoidance. An induced sensitivity could not be proven for the odorants, which suggest preference over imprinting.
Correlation of structural and functional maturation of olfactory receptor neurons
Human olfactory receptor neurons have the unique ability to regenerate in a short time span (about 7 days), which are of interest because of the possible applications including understanding of neurogenesis, regeneration and repair of the olfactory system, as well as, possible stimulation of growth of non-olfactory neural tissue. The present study attempts to correlate structural and functional maturation of olfactory receptor neurons (ORNs) using immunocytochemistry and fluorescence imaging of changes in odorant-elicitted intracellular Ca2+ concentration. Unlike previous studies, both the morphologically distinct, phase bright ORNs, and phase dark, “glial-like” cells, were tested for odorant-elicited responses and immunocytochemical staining. Results showed that many of these different cell types all respond to odorants but do not express the marker proteins associated with ORNs, indicating that these other non ORNs may also participate in the overall odorant response. These cells may be immature neurons, which respond nonspecifically to odorants, or supporting glial cells which exhibit nonspecific odorant-elicited or high potassium elicited responses. Thus, the development of functional attributes may be independent from structural maturation.
Effects of peroxynitrite on myelin basic protein expression and traffic in cultured embryonic chick brain neurons
Demyelination associated with diseases such as multiple sclerosis may be the result of oxidative damage to the myelin sheath surrounding neurons. One putative mechanism for this damage is peroxynitrite-induced death or dysfunction of oligodendrocytes through an unknown mechanism. In this study, cultured cerebral and cerebellar neurons from 14 day-old chick embryos were subjected to peroxynitrite to determine if this stress had a direct effect on the expression of myelin basic protein (MBP) in the central nervous system. Immunostaining was used to visualize the MBP expression in cells treated with 0 (control), 0.1 mM, and 1 mM peroxynitrite for 24 hours. MBP staining was visualized using fluorescence microscopy, quantified and measured to determine the amount of MBP expressed in individual cells. Results showed that peroxynitrite affected the cells from the cerebrum and cerebellum differently, The cerebral cells treated with 1 mM of peroxynitrite up-regulated MBP expression and increased trafficking while the cells treated with 0.1 mM only increased protein trafficking. The treated cells from the cerebellum expressed less protein and the protein trafficking with the cells appeared to be interrupted. These results suggest a differential effect of oxidative stress on neurons from different regions of the chick brain. Thus, the effects of oxidative stress vary in the different regions of the brain; these differences may account for the etiology of diseases such as multiple sclerosis, and has implications for its treatment and prevention.
The effects of anthropogenic carbon dioxide on the sea anemone Aiptasia pallida
In this experiment, I explored the potential effects of anthropogenic carbon dioxide on the sea anemone, Aiptasia pallida. Increased ocean acidity because of global warming has the potential to cause coral to bleach. Bleaching, or the loss of symbiotic dinoflagellates by coral and sea anemones, has also been linked to increased temperature and increased irradiance. Bleaching is caused by photoinhibition or the breakdown of the photosynthetic mechanism of the symbiotic zooxanthellae of the corals and sea anemones. I hypothesized that individuals of the sea anemone Aiptasia pallida would bleach when exposed to artificial sea water with decreased pH. I bubbled CO2 through artificial sea water and set up three treatment groups (pH 8.1, pH 7.8, and pH 7.4). Contrary to my hypothesis, the anemones only bleached significantly when exposed to the pH 7.4 treatment level. While all anemones used in the experiment appeared smaller and generally less healthy than the anemones in the aquarium, this difference was most prominent in the pH 7.4 treatment level. My results indicate that the pH 7.8 treatment level may actually aid the vitality of the zooxanthellae and subsequently the anemone itself by providing the zooxanthellae with extra CO2 for photosynthesis.
The Immunology of Celiac Disease
This honors thesis is a review of current literature on celiac disease. It is a review of primary journal articles, review articles, and one book with support from various physiology and immunology texts. The object of this thesis is to examine various aspects of the disease with major emphasis placed on its immunological mechanisms. Clinical presentation, complications, diagnosis and treatment of celiac disease are also addressed. Explanations have been suggested for the variety of symptoms associated with the disease.
Celiac disease has been described as both an autoimmune disease and an inflammatory bowel disease with autoimmune features. While inflammation plays a major role in the disease’s pathology, this thesis holds that celiac disease is in fact an autoimmune disease. This is due to the reactivity of the immune system to one of the body’s own enzymes. This thesis synthesizes the most currently available information and research on celiac disease and can be used best as an educational tool for those wishing to understand the disease in more detail.
A model of indirect nerve damage: implications for trigeminal nerve degradation associated with exposure to stressors associated with oral trauma and disease
Instances of dental pain are very prevalent and have a wide array of causes, ranging from bacterial infections to sequelae of surgical procedures. Such damage to tissue results in pain. Much remains unknown about the mechanisms of damage that cause pain, particularly in the nervous system. Therefore, the purpose of this study is to develop an in vitro model that can be used to understand mechanisms of nerve damage. Oxidative stress was selected as a method of damage to cultured chick brain neurons because oxidative stress is known to cause cellular degradation, and it is the causative agent of many diseases. Cultured cells were analyzed using immunocytochemistry techniques after exposed to either low or high treatments of oxidative stress the hope of understanding mechanisms behind the damage. Neurofilament, cadherin, and SNAP25 expression was measured for the treatments. The amount of protein, staining density, percent cell stained, and total area of the cell stained were measured for each treatment group and for each protein, and these values were normalized to the controls. The results from these experiments showed that oxidative stress causes changes in cellular morphology and widespread cellular degradation. The results also suggest that other cells (i.e. glial cells) are responsible for coping with various stressors, such as oxidative stress.
Facial Bumps of Phyllostomid Bats: LM Characterization
Faces of Phyllostomid bats have been previously noted to have varied epithelial patterns of projections associated with lips and chins (also known as warts, verrucae, bumps, facial projections, chin plates etc.). These projections are found on lips and chins of other families of bats as well, such as the family Mormoopidae suggesting there may be common morphological and functional features shared among bats. Facial and lip structures have received some attention from naturalists and have been previously described as glandular, while only one other morphological study suggested the presence of nerve elements. As a first attempt to morphologically characterize lip-associated and chin projections from some different bat species, I describe scanning electron, light microscopic, and immunohistochemical studies of epithelial and sub-epithelial structures from species of three genera of the family Phyllostomidae (Phyllostomus discolor, Artibeus jamaicensis, and Brachyphylla cavernarum). Tissues examined were from specimens collected, fixed, and preserved for other purposes but nonetheless were useful in revealing epithelial and dermal characteristics. Histomorphological and immunohistochemical preparations included techniques for general architecture and nerve tissue. Scanning electron microscopic studies revealed surface structure and arrangements, and another type of structure on the inner surface of lips projecting into the buccal cavity. Histological preparations of lips and chin bumps revealed hairless and glandless integumentary features, and numerous nerve elements. Epidermal pegs near the dermal-epidermal junction contained numerous, presumably mechanosensory, Merkel cells, but the arrangements of nerve endings and associated epithelial-cell contacts need transmission electron microscopic clarification. The lack of muscular and glandular efferently-controlled tissue in the epithelia and nerve endings and Merkel cells in the epidermis suggest mixed sensory functions for the bumps of Phyllostomid bats.
The role of NMDA mediated Excitotoxicity in Stroke
N-Methyl-D-aspartate receptors (NMDARs) are intriguing glutamate receptors believed to be important components of excitatory synapses, or synapses in which an action potential in a presynaptic neuron increases the probability of an action potential occurring in a postsynaptic cell. NMDARs are also believed to play a key role in learning and memory and are implicated in synaptic plasticity, or a synapse’s ability to strengthen. Most importantly to this honors thesis, however, is the role of NMDARs in excitotoxic damage. This excitotoxicity plays a role in neurodegenerative disease pathology, specifically in that of ischemic stroke (Von Engelhardt et al., 2007). Two main components of the NMDARs are believed to be involved with this damage: the NR2A and NR2B subunits. While much research has been completed regarding these two subunits, their roles in excitotoxicity are undetermined. It remains controversial that one of the subunits is neuroprotective while the other contributes to cell death, and some researchers believe it may be possible that both subunits contribute to the propagation of damage. In addition, some research indicates that the roles of the subunits in excitotoxicity are governed by developmental cues. This research aims to use previously developed DNA constructs to successfully express the desired proteins, so that other techniques may be used to identify interacting proteins. Once these other proteins have been identified, future researchers may use this data to determine which subunit is neuroprotective and consequently establish a biochemical pathway for possible drug targets.
The effect of temperature on the regenerative capacity of goldfish spinal neurons
After trauma to the mammalian spinal cord, damaged axons fail to regenerate, and undergo Wallerian degeneration. Past research has focused on overcoming the biochemical inhibitors to regeneration. Many of the studies that attempted to inhibit the blocks to regeneration have failed to produce CNS regeneration that would be significant enough for functional recovery in humans. In this current project, the physical treatment systemic cooling was used to promote regeneration in goldfish spinal cords. There were 19 experimental fish that received systemic cooling as a treatment, 13 control fish that did not receive the therapy, and 2 normal fish that did not undergo the spinal crush surgery. Histological analysis with Luxol Fast Blue (LFB) and ImageJ software revealed that there was not a statistical difference between the experimental and control fish. However, there were some statistically significant behavioral differences noted between the two groups. In addition to the behavioral and LFB results, there were differences between the tissue organization in control and experimental fish. Further studies should be conducted on systemic cooling to determine whether it is a viable therapy to promote recovery after spinal cord trauma.
The Role of the Optic Tectum in the Startle Response of Goldfish
The startle response is an escape behavior in goldfish which has been the subject of many experiments, but the majority of this focus has been on auditory stimuli as the trigger for the C-start response. Sensory organs send the information from stimuli to the Mauthner cells (M-cells), which mediate the startle response by sending signals down the spinal cord which cause the fish to turn away from the potentially dangerous stimuli (Faber et al 1989). This experiment focuses on the effect of visual stimuli on the startle response. More specifically, this experiment will examine the role of the optic tectum in producing the C-start response, since visual information is relayed from the eyes to the M-cells through the optic tectum (Zottoli et al 1987). Goldfish were tested for three days using both a visual stimulus and an acoustic/visual stimulus. After three days of testing, the left optic tectum of experimental fish was removed, causing blindness in the right eye. The fish were then tested in the same manner for three more days. The visual stimulus produced very few full C-start responses, before and after surgery. However, the response to the acoustic/visual stimuli was significantly decreased after removal of the left optic tectum. This suggests that the optic tectum plays a significant role in the goldfish’s ability to respond effectively to potentially dangerous stimuli.