Department: College of Arts and Sciences / Department of Biological Sciences ![[clear]](close-x.png "Remove this limiter")
61 matches in the database.
These are records: 1 - 30.
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1.
Antibus, Doug E.
Molecular and Cultivation-based Characterization of Ancient Algal Mats from the McMurdo Dry Valleys, Antarctica.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2009, Kent State University
► The McMurdo Dry Valleys in Antarctica present an opportunity for viable bacteria…
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▼ The McMurdo Dry Valleys in Antarctica present an opportunity for viable bacteria and bacterial DNA to be preserved over millennial-scale periods of dormancy because 1) the cold and dry climate of the Dry Valleys favors preservation of biological materials and 2) many Antarctic microbes are adapted to withstand stresses resulting from long periods of dormancy. Because of this potential for microbial preservation, the Dry Valleys may be the recipients of a legacy of genetic diversity dating from the Holocene, when the valleys were occupied by glacial lakes, although this possibility has not been previously investigated.This study examined samples of algal mat from the McMurdo Dry Valleys representing a chronological sequence in 14C age from 8 to 26,539 years before present. Research focused on the recovery of bacterial DNA and the examination of bacterial diversity by bacterial 16S rRNA gene clone libraries, as well as the recovery of cultivable bacteria from the samples. Bulk DNA abundance, bacterial DNA integrity, and the abundance and diversity of cultivable bacteria all declined with increasing sample age, matching expected patterns for ancient materials. Clone sequences belonging to the Cyanobacteria were abundant in a modern sample but absent from ancient samples. In contrast, Firmicutes 16S rRNA gene sequences and cultivable Firmicutes were abundant in ancient samples. The abundance of Firmicutes supports the inference that bacterial gene sequences and cultivable bacteria from samples were authentically ancient, as Firmicutes are not common in Antarctic soils. Additionally, anaerobe sequences were abundant in clone libraries, which would be expected for Antarctic algal mats rather than mineral soils. BOX-PCR genotyping was applied to 105 isolates belonging to the Firmicutes genus Sporosarcina from ancient and modern samples. Previous research in the McMurdo Dry Valleys has found that highly similar 16S rRNA gene sequences are distributed throughout the landscape, suggesting that alpha and gamma richness of bacterial species are similar. In this study, little overlap of Sporosarcina genotypes between samples was observed, suggesting that gamma richness of genotypes is greater than alpha richness. Isolates displayed differential responses to growth temperature, which was associated with BOX-PCR genotype. Genotypes were also unevenly distributed over temperature and medium treatments used in initial cultivation attempts, suggesting that genotypes are adapted to different substrate and temperature conditions.
Advisors/Committee Members: Blackwood, Christopher.
Subjects: Biology
Keywords: McMurdo Dry Valleys; Antarctica; microbial dormancy; ancient microbes
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2.
Barlett, Melissa Ann.
The Effects of Nutrient Type and Stoichiometry on Bacterial Community Composition in Streams and Wetlands.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2007, Kent State University
► Nitrogen and phosphorus additions from various sources can change our aquatic systems,…
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▼ Nitrogen and phosphorus additions from various sources can change our aquatic systems, both through increased nutrient concentrations and changes in nutrient stoichiometry. Because bacteria are important in the cycling of nutrients and aquatic food webs, understanding how stoichiometry affects the bacterial community enhances our understanding of how these changes potentially affect aquatic ecosystems as a whole. This study examined the interactions between N:P ratios and sources and bacterial communities. To examine these interactions, a variety of methods were used. A field study was conducted at three sites along the Mahoning River. Both microcosm studies in the lab and mesocosm studies in the Aquatic Ecology Research Facility (AERF) were used to examine the effects of nutrient manipulations. These experiments used fluorescent in situhybridization (FISH) to determine the abundance of Domain Bacteria, alpha-, beta-, and gamma-proteobacteria as well as the Cytophaga-Flavobacteria(CF) cluster. Denaturing gradient gel electrophoresis (DGGE) was used in the mesocosm experiment to get a picture of the entire community. Finally, a competition experiment was conducted between two aquatic isolates, a B. cepaciaand a Flavobacteriumsp. A few relationships were seen between bacterial taxa and nutrients. The beta-proteobacteria were found in increased numbers under high N:P ratios. Whereas the CF cluster had lower numbers under high N:P ratios. Both the beta-proteobacteria and the CF responded more to ammonium than nitrate, however alpha-proteobacteria responded to nitrate more than ammonium. In the microcosm studies, there also appeared to be a change in the ammonium uptake and release. When ammonium was supplied in high concentrations, it was taken up by the bacterial community. When ammonium was not supplied, it was released by the bacterial community. Seasonal factors appeared to have a greater impact on all natural bacterial communities than nutrient manipulations. During the competition experiment, the both of the isolates had higher growth rates when combined than when separate. The Flavobacteriumalso showed a decrease in growth rates when supplied with nutrients in organic forms. Seasonal changes and carbon sources need to be studied more thoroughly to better understand their impact on the bacterial community and their interaction with nutrient effects.
Advisors/Committee Members: Leff, Laura G.
Keywords: Bacteria; Biofilms; Nitrogen; Phosphorus; Stoichiometry
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3.
Barriball, Kelly.
Population structure and mating system of the invasive shrub Lonicera maackii in Ohio.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2012, Kent State University
► In this thesis, I studied the genetic structure and mating system of…
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▼ In this thesis, I studied the genetic structure and mating system of the invasive shrub Lonicera maackii (Rupr.) Maxim. (Caprifoliaceae). This shrub is native to eastern Asia, and was introduced to the U.S. in 1898 for horticultural purposes. Lonicera maackii is currently considered an aggressive invasive plant, and when present, is often the dominant understory shrub in forested areas of southwest Ohio. First, I tested the hypothesis that L. maackii is spreading into previously uncolonized areas by way of multiple long-distance dispersal events followed by local expansions. I examined the genetic structure of 42 populations of L. maackii from Hamilton, Franklin, Butler, Preble, Darke and Miami counties in Ohio, and Wayne County in Indiana. Darke County is the most recent area in Ohio experiencing a rapid colonization. My findings revealed high allelic diversity (Na = 8.13), high heterozygosity (Ho = 0.71) and low levels of inbreeding (FIS = 0.06) across all populations. Low population differentiation (FST = 0.08) was found between populations, with only 10% of the molecular variation attributed to differences among populations. A significant correlation between geographic and genetic distance was found among all possible pairwise populations (Mantel correlation = 0.23, p = 0.01) suggesting that established populations may expand their range as advancing fronts. Further analysis using the program Structure revealed significant levels of admixture within individuals and within woodlots, suggesting that, in addition to local expansion of established woodlots, animal-mediated long-distance seed dispersal aids in the spread of L. maackii and plays a key role in maintaining genetic diversity. For my second study, I examined the mating system of L. maackii in one woodlot, comparing edge and interior plants. My findings support the notion that L. maackii is a predominantly outcrossing plant (tm = 0.97), with no significant differences between the outcrossing rates among edge and interior plants. However, there were differences in the correlation of paternity among progeny of edge and interior plants, suggesting differences in the average number of pollen donors siring their seed crop; effective number of pollen donors (Nep) was lower for edge plants. I found significant heterogeneity in allele frequencies among pollen and ovule for both edge and interior plants. I argue that differences in pollen frequencies and number of sires is most likely due to the disparities in visitor community, the time and intensity of flower anthesis among pollen donors, and non-random mating of genotypes during outcrossing events.
Advisors/Committee Members: Rocha, Oscar.
Subjects: Biology; Botany; Ecology
Keywords: Lonicera maackii; invasive plant; population genetics; mating system; outcrossing rate
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4.
Baxter, Alyssa M.
Relating spatial patterns of denitrification and bacterial community structure to environmental conditions in streams.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2010, Kent State University
► Land use is a key factor influencing the health of a stream.…
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▼ Land use is a key factor influencing the health of a stream. Agricultural land use, in particular, can have detrimental effects on water quality, habitat, and biological assemblages. Artificially high nitrogen loading from fertilizer runoff can lead to eutrophic conditions in affected streams, and may significantly alter the composition of aquatic vertebrate, invertebrate and microbial communities. In this study, six streams of varying land use type (three impacted by high intensity agriculture and three in mixed-use watersheds) in Indiana and Ohio were sampled in summer and fall for a variety of chemical, physical and biotic factors. Nested ANOVAs determined differences in these factors longitudinally within each stream, and subsequent one-way ANOVAs determined significant differences in these factors based on season and land use type. The abundance and diversity of the whole bacterial community and the denitrifying community were examined using quantitative PCR and terminal restriction fragment length polymorphism (T-RFLP) analysis of the 16S rRNA gene (all bacteria) and the nosZ gene (specific to denitrifiers). Detrended canonical correspondence analysis and multiple linear regression were used to elicit possible predictive relationships between various factors and denitrification rate and denitrifier abundance. Streams impacted by high intensity agriculture were found to have significantly higher nitrate, soluble reactive phosphorus and dissolved oxygen concentrations than mixed-use streams during both seasons. These streams also contained a significantly higher proportion of pollution tolerant macroinvertebrate taxa. Mixed-use streams had significantly higher dissolved organic carbon concentrations and higher total bacterial abundances than agricultural streams. Multivariate analyses suggested nitrate concentration was an important predictor variable for both denitrification rate and denitrifier abundance. Denitrification rates and denitrifier abundance were significantly higher in agricultural streams than mixed-use streams, and generally higher in summer than fall. Redundancy analysis of T-RFLP data suggested that a larger portion of the variation among stream bacterial communities was explained when streams of differing land use type were compared. Overall, the data suggested possible relationships between denitrifier community abundance, diversity, and function, as well as the possibility to predict stream denitrification rates using chemical, physical and community factors.
Advisors/Committee Members: Leff, Laura.
Subjects: Ecology; Environmental science; Microbiology; Molecular biology
Keywords: denitrification; bacteria; bacterial community structure; TRFLP; nosZ; bacterial abundance; stream; land use; agriculture; macroinvertebrate; nitrogen
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5.
Benvenuto, Chiara.
Precopulatory mate guarding behavior in clam shrimp: a case of intersexual conflict.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2008, Kent State University
► Precopulatory mate guarding is a complex behavior and a challenging example of…
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▼ Precopulatory mate guarding is a complex behavior and a challenging example of intersexual conflict. A conflict is initiated when the sexes are in disagreement on the mate guarding duration: males decide to start guarding, because their cost (i.e., time investment) is lower than their benefit (mating event), but females are resisting because their cost (in term of energy) is higher than their benefit (mating event). I used clam shrimp (branchiopod crustaceans) as my study organisms, which allow for the unique opportunity among animals to compare the same behaviors among species characterized by different mating systems: dioecy (co-presence of male and females) and androdioecy (co-presence of males and hermaphrodites). I analyzed mate guarding starting from the proximate mechanisms of this behavior. Males are not attracted to the opposite sex (while hermaphrodites are) but swim fast searching for hermaphrodites close-to-receptivity. Males do not react to molting hormone as a soluble cue in the water or as a direct contact cue on the hermaphrodites’ carapace. I analyzed costs and benefits for each sex (guarding is more costly to hermaphrodites than to males), I created a size “power” asymmetry between males and hermaphrodites (and confirmed that the stronger sex can better control the guarding duration), and I measured the optimal guarding time of each sex in order to compare it with the compromised guarding time. The results perfectly matched a theoretical model (Jormalainen, 1998): hermaphrodites “prefer” to be guarded less than the compromised guarding time, while males are willing to guard longer. I compared four species (two dioecious and two androdioecious) in order to assess the influence of the mating system on mate guarding strategies. The benefit of outcrossing is higher for females than hermaphrodites (who can self-fertilize if guarding is too costly) while males experience different social environments in the two mating systems (due to different sex ratios). As a result, dioecious species guarded longer than androdioecious species. Finally, I observed a dioecious species in the field to verify my laboratory results, performing in this way a comprehensive analysis of mate guarding behavior as a case of intersexual conflict in these interesting crustaceans.
Advisors/Committee Members: Weeks, Stephen C.
Subjects: Behaviorial sciences; Biology; Ecology; Zoology
Keywords: Crustacea; Branchiopoda; Clam shrimp; Dioecy; Androdioecy; Intersexual conflict; Precopulatory Mate guarding; Eulimnadia texana; Limnadia badia; Limnadopsis tatei; Eulimnadia dahli
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6.
Brager, Allison Joy.
Roles of the circadian and reward systems in alcoholism.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2011, Kent State University
► The circadian timing system is closely tied to the reward system. This…
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▼ The circadian timing system is closely tied to the reward system. This dissertation addresses primary mechanisms for alcoholism through the assessment of ethanol disruption to the mammalian circadian pacemaker located in the suprachiasmatic nuclei (SCN) of the hypothalamus. The mouse strain utilized (C57BL/6J) demonstrated moderate ethanol intake (~12 g/kg/day), preference (50%), and relapse risk. Chronic ethanol intake, its withdrawal, and subsequent re-introduction had adverse effects on entrainment to a weak photic stimulus and the temporal structure of general circadian locomotor activity. An acute, systemic ethanol challenge and chronic ethanol intake dose-dependently attenuated light-induced phase-delays of behavioral circadian rhythms. In vivo microdialysis administration of ethanol (500 mM) in the SCN revealed that the SCN is a direct site of ethanol disruption to photic entrainment processes. An acute ethanol challenge at midday attenuated 8-OH-DPAT-induced phase-advances, while chronic ethanol intake and an intra-SCN microdialysis perfusion had no effect on this response. Disruption of behavioral circadian entrainment through long-term housing under constant light potentiated ethanol intake and preference. A nonfunctional homolog of the clock gene, PER2, in wild-type mice also elevated ethanol intake and preference, owing, in part, to an additional circadian phase of ethanol intake. Ethanol intake and preference associated with PER2 gene mutations were rescued to wild-type levels through a systemic administration of acamprosate or constant-release acamprosate microimplants in circadian and reward areas. Brain mapping with acamprosate microimplants also identified circadian (SCN, intergeniculate leaflet) and reward (ventral tegmental, accumbal, and penducular areas) sensitive to the (ethanol) suppressive effects of acamprosate, though the extent of suppression was significantly less in PER2-mutant vs. wild-type mice. These results suggest that the disruptive effects of acute (binging) and chronic ethanol abuse on circadian entrainment can facilitate a downward spiral of alcohol dependence and chronobiological disturbances. This research also demonstrates the need for enhanced behavioral and genetic screening and circadian treatment strategies for the treatment of alcoholism and prevention of relapse.
Advisors/Committee Members: Glass, J. David.
Subjects: Behavioral Sciences; Biomedical Research; Neurobiology; Neurosciences; Physiology; Psychobiology
Keywords: ethanol, circadian, clock gene, acamprosate, microdialysis, mouse, reward, glutamate, serotonin
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7.
Breidenbaugh, Mark.
Testing Effects of Aerial Spray Technologies on Biting Flies and Nontarget Insects at the Parris Island Marine Corps Recruit Depot, South Carolina, USA.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2008, Kent State University
► Biting flies are pests and potential vectors at the Marine Corps Recruit…
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▼ Biting flies are pests and potential vectors at the Marine Corps Recruit Depot, South Carolina (PIMCRD). To prevent the disruption of military training, aerial pesticide applications using a US Air Force (USAF) C-130H are made. Biting midge (Ceratopogonidae) and mosquito (Culicidae) seasonal abundance and diel activity patterns were analyzed on the PIMCRD using CO2-baited suction traps from November 2001 – November 2004. Eighteen mosquito and 3 biting midge species were collected with Aedes taeniorhynchus the most abundant mosquito (42.7% of total) and Culicoides furens the most abundant (86.2% of total) biting midge. Activity of most biting midges and mosquitoes were highest the first 2 hours following sunset. Species of biting flies were present in all months. A new fuselage boom configuration on the USAF C-130H aircraft was characterized to determine the droplet spectra produced with flat-fan nozzles (8001, 8005). Across all trials, median droplet diameter for 8001 and 8005 nozzles were 11.4 µm and 54.3 µm, respectively. In addition, biting midge and mosquito mortality were analyzed with public health insecticides. Mosquito mortality was 100% 639 m downwind in single pass trials using bioassay cages and Dibrom. In wide-area applications of Dibrom, an 83-86% reduction of biting flies was observed. Overall, these field trials indicated that this new fuselage boom configuration creates effective droplet sizes and swath widths (i.e., 610 m) for USAF aerial vector control at the PIMCRD and elsewhere. Responses of nontarget insects to aerial pesticide applications were also studied. Malaise traps and yellow pan traps were used to determine nontarget insect diversity and abundance with before and after impact analysis. Total nontarget insect abundance was lower after sprays in Malaise trap collections in 2003 (P < 0.025), with these numbers decreasing by about 50%. However, there were no differences in total numbers after sprays in pan traps in 2005 (P = 0.756). Shannon diversity indices were not different after sprays in either year indicating that sprays had minimal impact on overall community biodiversity. Results indicate that there are some impacts on nontarget species from aerial sprays but applying sprays at dusk helps minimize these impacts while still controlling biting flies.
Advisors/Committee Members: de Szalay, Ferenc.
Subjects: Ecology; Entomology; Public health
Keywords: vector control; biting midges, mosquitoes, Culicidae, Ceratopogonidae, Culicoides, adulticiding; AGDISP; droplet characterization
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8.
Calderon-Salgado, Esther Lilia.
Effect of progesterone and RU486 on cisplatin resistance in OV2008 and C13 ovarian epithelial cancer cell lines.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2008, Kent State University
► Ovarian cancer is the sixth most common cancer and has the highest…
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▼ Ovarian cancer is the sixth most common cancer and has the highest mortality rate of any gynecological cancer among women. About 90% of ovarian cancers arise from the ovarian surface epithelium and are referred to as epithelial ovarian cancer (EOC). EOC can be easily overlooked due to symptoms not typically associated with ovarian cancer. The location and the asymptomatic nature of EOC contribute to its high mortality. Current treatment comprises cytoreductive surgery; chemotherapy with the platin based drugs such as: carboplatin and/or cisplatin; and radiation therapy. However combined resistance, high toxicity, and extreme side effects of these drugs has lead to the search for alternative treatments. Current evidence suggests that a combination of progesterone and chemotherapy could be a potential alternative or auxiliary treatment for EOC. Although promising, little is known about the signal transduction pathway of either cisplatin or progesterone. It has been suggested that progesterone up-regulates tumor suppressor pathways and cisplatin has been linked to apoptotic pathways. Thus, the hypothesis for this research is that exposure of ovarian epithelial cancer cells to progesterone will enhance the effectiveness of cisplatin treatment, via a classical steroid receptor mechanism. OV2008 (cisplatin sensitive) and C13 (cisplatin resistant) ovarian cancer cell lines were used for the experiments. Treatments were repeated in triplicate and were carried out every 24 hrs. Cells were treated with 8µM progesterone alone, 8µM RU486 alone, or a combination of both. Cells treated with wortmannin (1µM) received 1hr pre-treatment. The following day all other treatments were continued, and cisplatin (30µM) and/or LiCl (20mM) treatments were started. MTS assay and tryphan blue exclusion methods were used to test efficacy of treatments. Thus it was concluded that: neither progesterone nor RU486 alone alter the response of OV2008 or C13 cells to cisplatin. However, in combination the two decrease cell survival in both lines and appear to sensitize C13 cells to cisplatin. The pathway to decrease cell survival is different for the progesterone and RU486 combination than cisplatin, while the cisplatin effect is dependant on GSK-3β, the progesterone and RU486 do not appear to use either PI3K, GSK-3β, or Ras-Raf/MEK. The progesterone and RU486 combination should be considered as a possible adjuvant treatment with cisplatin.
Advisors/Committee Members: Stalvey, John.
Subjects: Biology; Biomedical research
Keywords: Ovarian cancer; progesterone; cisplatin
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9.
Chapman, Eric George.
Bayesian Phylogenetics of Snail-Killing Flies (Diptera: Sciomyzidae) and Freshwater Mussels (Bivalvia: Unionidae): Implications of Parallel Evolution, Feeding Group Structure and Molecular Evolution.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2008, Kent State University
► This dissertation utilizes maximum likelihood optimization of morphological and molecular characters onto…
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▼ This dissertation utilizes maximum likelihood optimization of morphological and molecular characters onto molecular phylogenies of snail-kiling flies and freshwater mussels to study character evolution. The larvae of snail-killing flies (Diptera: Sciomyzidae) display a wide range of feeding behaviors, being predators, parasitoids, or saprophages of a wide variety of gastropod mollusks. The genus Tetanocera is particularly interesting because its species occupy five distinct larval feeding behavioral groups with each species’ larvae living in one of two general habitat types (aquatic or terrestrial). Maximum likelihood analyses of character state transformations showed significant correlations between habitat transitions and changes in four larval morphological characteristics. Evidence is provided that phylogenetic niche conservatism was responsible for the maintenance of aquatic-associated larval morphological character states, and concerted convergence and/or gene linkage was responsible for parallel morphological changes that were derived in conjunction with habitat transitions. Maximum likelihood optimization of larval feeding behavioral groups estimated that the ancestor to Tetanocera was an aquatic predator of non-operculate pulmonate snails, and that Tetanocera lineages made at least eight feeding group transitions during their phylogenesis. As a consequence, Tetanocera lineages transitioned from aquatic to terrestrial habitats at least six times independently. Freshwater unionoidean bivalves have distinct maternal (F) and paternal (M) mtDNA genomes. Male unionoidean bivalves have a ~550bp 3' coding extension to the cox2 gene (Mcox2e) that is apparently absent from all other metazoans. Molecular sequence analyses indicate that this region is unique to unionoidean bivalves, is functional and likely the result of a single >65 MY old insertion event, has relatively high rates of evolution in its primary and secondary structures including variability in transmembrane helix (TMH) number, shows instances of site-specific positive selection, shows an overall pattern of purifying selection that leads to the preservation of the TMH and hydrophilic C-terminus tail sub-regions with variation in pedicted TMH number stemming from substitution-based processes, and has a more conserved C-terminus tail that is likely biologically active because it contains functional motifs. These results provide supporting evidence that MCOX2e has a novel reproductive function within unionoidean bivalves and indicate that unionoidean bivalve MCOX2 is a chimeric animal mtDNA-encoded protein.
Advisors/Committee Members: Hoeh, Walter R.
Subjects: Biology
Keywords: Snail-kiling flies; Diptera; Sciomyzidae; freshwater mussels; feeding behavior evolution; Unionidae; Ambleminae; systematics; Bayesian phylogenetics; maximum likelihood; character optimization; DUI; diversifying selection
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10.
Chiappini-Williamson, Christine.
Developmental Effects of Estrogen on the Superior Cervical Ganglion and Hypertension.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2009, Kent State University
► Essential hypertension is a multi factorial disease characterized by persistent resting blood…
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▼ Essential hypertension is a multi factorial disease characterized by persistent resting blood pressure (bp) above 140/90mmHg affecting approximately 33% of adult Americans. The spontaneously hypertensive rat (SHR) is the model strain and exhibits systolic pressure greater than 200mmHg with increased sympathetic activity. The superior cervical ganglion (SCG) of the SHR contains more neurons than that of the Wistar-Kyoto (WKY) control. This strain difference develops early in the neonatal period in a pattern similar to that of neuronal sex differences in the SCG of the Sprague-Dawley strain. Sex differences in neuron number develop in the Sprague-Dawley by postnatal day 15 (P15) and can be manipulated by estrogen and aromatizable androgens. The purpose of this dissertation was to confirm the presence of strain differences, establish the presence of sex differences in neuron number and determine the age of onset as well as determine the effect of neonatal aromatase blockade on adult neuron number and bp in the SHR and WKY. Cell counts were performed on 6μ paraffin sections stained with toluidine blue using the physical dissector method in ganglia from untreated P15 and adult SHR and WKY male and female rats. Estrogen synthesis was blocked by administration of a chemical aromatase inhibitor to male SHR and WKY rats from the day of birth t P15. Pups were raised by their mothers until sacrifice at 8wks of age following the measurement of bp. The SCG was removed and neurons counted by the same method. No strain differences in neuron number were found at any age in untreated animals. Sex differences were found in adult ganglia of both strains but not in either strain prior to P15. Neonatal aromatase blockade successfully reduced both bp and neuron number in males of both strains. Therefore it was concluded that there are not strain differences in SHR and WKY neuron number at any age, adult sex differences are present but do not develop prior to p15 and estrogen does play a role in the establishment of neuron number and blood pressure in both of these strains.
Advisors/Committee Members: Salisbury, Ronald.
Subjects: Biology
Keywords: Estrogen, development, superior cervical ganglion, hypertension, SHR
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11.
Clark, Jennifer Marie.
Abiotic and biotic factors affecting size-dependent crayfish (Orconectes obscurus) distribution, density, and survival.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2009, Kent State University
► Crayfish are important components of community structure, trophic cascades, organic matter processing,…
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▼ Crayfish are important components of community structure, trophic cascades, organic matter processing, and species replacements and have been considered keystone species and ecosystem engineers in lotic systems. Understanding the role that spatio-temporal variability of biotic and abiotic factors plays in determining crayfish distribution is critical to assessing the impact of this organism in an ecosystem. In this study, habitat-specific effects of current velocity, grain characteristics, water depth, predation, and competition for food on size-specific crayfish (Orconectes obscurus) populations were assessed in a 4th-order stream. Crayfish were distributed among deep pools, shallow pools, and riffle habitats in a size-specific fashion with small crayfish occupying shallow pools and riffles and large crayfish occupying shallow and deep pools. Medium crayfish, however, were distributed across all three habitat types. In general, O. obscurus preferred habitats with low current velocity. Larger crayfish were negatively associated with current velocity and seemed to be excluded from riffle habitats. In contrast, small and some medium crayfish were able to tolerate the higher current velocity of riffle habitats and occupied them at low densities. Along with current velocity preferences, small and medium crayfish preferred shallow water depths whereas large crayfish preferred deep water habitats. Further, large rocky substrate appeared to be an important structuring mechanism for small and medium crayfish, as these two size classes were positively correlated with increased grain sizes. Large crayfish, however, were associated with habitats dominated by small grain sizes. Although crayfish densities seemed to correlate strongly with some abiotic variables in field surveys, interactions between abiotic variables and predation risk were not consistent in the tethering assays, implying that most abiotic variables, did not mediate predation events in this population of crayfish. Although all crayfish sizes were vulnerable to predation, only small crayfish showed consistent differences in survival across habitats whereas medium and large crayfish generally had similar survival across all three habitat types. In summary, small crayfish distributions appeared to be structured primarily by predation and substrate availability whereas larger crayfish appeared to be structured by a combination of substrate availability, current velocity, and competition for food resources.
Advisors/Committee Members: Kershner, Mark.
Subjects: Ecology
Keywords: crayfish; stream; predation; current velocity; water depth; grain size; resource competition
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12.
Das, Mitali.
Microbial Community Structure and Interactions in Leaf Litter in a Stream.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2006, Kent State University
► Leaf litter is an important energy source in forested streams, and is…
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▼ Leaf litter is an important energy source in forested streams, and is degraded primarily by fungi (mainly hyphomycetes) and bacteria. Not much is known about the diversity of non-hyhomycete/sporulating fungi, bacteria and actinomycetes on leaf litter and interactions among these groups. Three aspects of microbial ecology on decomposing leaves were examined. First, the diversity of fungi, bacteria and actinomycetes on decaying sugar maple and white oak leaves was examined for 181 days using denaturing gradient gel electrophoresis (DGGE). Fungi exhibited greater biomass and ribotype richness than bacteria. Temporal variation but no leaf-specific differences were observed in microbial community structure suggesting that the microorganisms on either leaf species were generalists and could exploit both resources equally well. Second, the community composition of fungi was examined using a traditional method (conidia staining) as well as cultivation and phylogenetic analysis. Conidia staining revealed that Tetrachaetum elegans was dominant, while 18S rRNA gene sequencing of cultured isolates revealed mainly non-hyphomycetes (Ascomycota) and a greater richness than microscopy. Only 12 isolates were conclusively identified of which two were hyphomycetes. Third, interactions between T. elegans and two bacterial isolates, CM8 and Kanr12 (antibiotic-resistant) studied under varying dissolved organic carbon (DOC) regimes showed no influence of DOC amendment on microbial biomass. No synergism/antagonism was observed between T. elegans and bacteria probably because nutrients were not limiting. Both bacteria belong to the metabolically versatile Cytophaga-Flavobacterium cluster, which may indicate that they could exploit the resources equally well. Hence, no discernible differences were observed in their response to the fungus. This study demonstrated that ecological niche of microorganisms, stage of decay and time of exposure are more important determinants of microbial community structure than leaf quality.
Advisors/Committee Members: Laura G. Leff, Todd V. Royer.
Keywords: fungi, bacteria and actinomycetes; Ascomycetes and hyphomycetes; leaf litter in streams; PCR-DGGE and 16S rRNA or 18S rRNA gene sequencing; Neighbor joining tree; fungal bacterial interaction; DOC amendment; antibiotic resistant bacteria
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13.
Davis, Melissa Anne.
The Floristic Survey of Geauga County, Ohio: 50 Years of Change.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2010, Kent State University
► A floristic survey of Geauga County was conducted during the 2008 through…
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▼ A floristic survey of Geauga County was conducted during the 2008 through 2009 growing seasons. In conjunction with The Geauga Park District, more than 6000 acres (2,428.114 hectares) in twelve open parks and other preserves was surveyed. Herbarium specimens at the Tom S. and Miwako Cooperrider Kent State University Herbarium (KE) and The Cleveland Museum of Natural History Herbarium (CLM) were examined for additional plant specimens. From field work and herbarium surveys, a catalogue of historical and modern specimens was compiled. The main objectives of the study were to: 1) compare historical and current herbarium records to the present flora; 2) use geospatial technology to demonstrate change in vegetation over a 50 year period; 3) analyze differences in non-native and invasive plant distributions; and 4) document new native and non-native plant colonization and report possible extirpated species. Distribution maps at the township level are included for the plant species. The results show a slight increase in actual species counts of native and non-native species and a 0.9% loss of vegetation area over the 50 year period. Native species constitute approximately 80% of the current flora while non-natives and invasive plants comprise approximately 20% of the current flora.
Advisors/Committee Members: Andreas, Barbara.
Subjects: Botany
Keywords: Floristic Survey; Geauga County, Ohio
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14.
Drinkard, Maureen Katherine.
IMPACTS OF A FLOOD PULSING HYDROLOGY ON PLANTS AND INVERTEBRATES IN RIPARIAN WETLANDS.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2012, Kent State University
► I tested the impacts of flood-pulsing on wetland invertebrates and plants along…
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▼ I tested the impacts of flood-pulsing on wetland invertebrates and plants along small streams in northeast Ohio. The Flood Pulse Concept (FPC) was developed in large rivers (e.g. Amazon, Danube, and Mississippi rivers). It describes the ecological impacts when rivers flood adjacent riparian habitats, which are a mosaic of permanent flooded wetlands, intermittently flooded wetlands, and terrestrial habitats. Flood-pulsing produces resource subsidies (e.g., water, nutrients, organic matter). Flooding also creates stresses (anoxia, desiccation, high levels of toxins, sediment erosion and deposition) in the wetlands. Floodplain biota are adapted to the predictable flood regime in large rivers. Furthermore, coarse woody debris (CWD) from fallen trees provides a microclimatic refugia for soil organisms in floodplains. As a result, biodiversity and production are usually higher in flood-pulsing wetlands than other wetland habitats. In my dissertation, I used wetland mesocosms at the on-campus Herrick Aquatic Ecology Research Facility (HAERF) to test how the short unpredictable floods in small streams affect wetland plants and invertebrates. I found that flood pulsing creates stresses that control plant community structure in the intermittently flooded zone. There was lower emergent plant diversity and plant cover in the flood-pulse treatment. However, aquatic invertebrates and plants in permanently flooded pools were not affected. I also sampled emerging insects in flood-plain wetlands at Mud Brook Preserve (MBP) and at HAERF. Insect communities were different in permanent pools and intermittently flooded zone at MBP showing that drawdowns are an important environmental factor. The permanent pools at HAERF and MBP were also different, suggesting that mesocosms did not simulate all natural environmental conditions. I tested the impact of CWD by testing naturally and artificially felled trees. Invertebrate communities were varied by region of the floodplain. However, there were few differences in sites with and without CWD suggesting that habitat conditions (soil moisture, temperature) structure soil invertebrate communities. While CWD had few short-term impacts it may be significant at a landscape scale. Overall, the unpredictable short floods in headwater wetlands create both benefits and stressors, but the net impact was negative. Therefore, some aspects of the Flood pulse concept are not applicable to headwater systems.
Advisors/Committee Members: de Szalay, Ferenc.
Subjects: Aquatic Sciences; Biology; Entomology; Environmental Management; Environmental Science; Environmental Studies; Hydrologic Sciences; Hydrology; Natural Resource Management; Plant Biology; Plant Sciences; Water Resource Management
Keywords: Flood pulsing; wetland; floodplain; riparian; aquatic invertebrate; coarse woody debris; insect emergence; zonation
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15.
Feinstein, Larry M.
Microbial Functional Activity and Diversity Patterns at Multiple Spatial Scales.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2012, Kent State University
► The work in this dissertation was concerned with quantifying microbial diversity and…
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▼ The work in this dissertation was concerned with quantifying microbial diversity and biogeochemical activity patterns in order to understand processes that influenced pattern formation and variability. Microbial patterns and processes were then compared to theory that has been developed for macrorganisms. This work documented evidence for common macro-scale patterns at the microbial scale including a taxa-area relationship, distance-decay, and increased resource heterogeneity associated with an increase in productivity (the species complementary hypothesis). Novel aspects of the research within this dissertation included quantifying microbial communities on entire, discrete habitat patches (senesced leaves), documentation of differential fungal taxa-area relationships, documentation of distance-decay patterns across discrete adjacent habitat patches, quantification of bias associated with a common DNA extraction protocol, and recommendations for improving the ability to quantify microbial communities. Fungal community composition was shown to be influenced by energy availability. Neutral processes were found to influence individual community assembly while evidence for species-sorting processes was found across a) adjacent communities and b) the forest landscape. Community composition and microbial dynamics (productivity, extracellular enzyme activity) were documented to have an important role in saprotrophic carbon-cycling activity. Finally, the interaction between community dynamics and litter mixtures was documented, providing evidence of an ecological process whereby microbial activity increases ecosystem exergy.
Advisors/Committee Members: Blackwood, Christopher.
Subjects: Ecology; Microbiology
Keywords: microbial diversity; carbon cycling; community assembly; DNA extraction bias
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16.
Fiester, Steven E.
Characterization of Optically Active Biopolymers.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2011, Kent State University
► All systems have a universal tendency toward disorder. Biological systems must therefore…
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▼ All systems have a universal tendency toward disorder. Biological systems must therefore invest energy in order to maintain homeostasis. Salmonella flagella and g8p, the coat protein of fd bacteriophage, are two systems that use self-assembly to maintain order while minimizing this energy expenditure. Salmonella flagella are created through the self-assembly of flagellin protein monomers to form a filament. These flagellar filaments self-organize into bundles in order to form a rigid “propeller” for locomotion. The amino acid monomers of g8p form proteins that self-assemble through hydrophobic interactions around viral DNA (to protect the DNA from degradation). Both flagella filaments and g8p self-assemble with individual filaments aligning along a common direction, thus exhibiting liquid crystalline phases. Cross-polarized microscopy was used to characterize the liquid crystal textures in concentrated systems of flagella and g8p. Helical flagella possessed chiral nematic textures indicative of an arrangement of filaments approaching parallel alignment. Straight flagella possessed a nematic texture indicating a parallel alignment of filaments. Filaments with a smectic texture were observed in concentrated suspensions of g8p suggesting a layered organization of g8p. Atomic force microscopy and scanning electron microscopy supported these data, and suggested that g8p proteins further assemble into films such that the films wrap about a central axis to form filaments of concentric layers. As a possible application of liquid crystal biopolymers in vitro, the liquid crystalline phases of chitin, flagella and fd bacteriophage were investigated as potential sensors to detect bacteria. Sensor development exploited well documented changes of liquid crystal textures resulting from contaminating materials that exceed a critical size, thus appearing as defects in the respective liquid crystal textures. Salmonella cells and streptavidin-coated beads (as bacterial surrogates) were detectable at an initial concentration of 106 cells or beads/mL in chitin. Beads were not detectable to 106 beads/mL in liquid crystal phases of flagella or fd bacteriophage, likely due to the inherent flexibility of flagella and fd bacteriophage. This dissertation characterizes several biopolymers with different liquid crystal arrangements, characterizes their potential as sensors and offers numerous alternatives to traditional synthetic liquid crystals.
Advisors/Committee Members: Woolverton, Christopher.
Subjects: Biology; Biophysics; Materials Science
Keywords: liquid crystal; biopolymer; mesophase; bacteria detection; bent-core
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17.
Floro, Eric R.
Mitochondrial heteroplasmy in Mimulus guttatus.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2011, Kent State University
► Eukaryotic organisms have two distinct genomes—the nuclear genome and the cytoplasmic genome.…
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▼ Eukaryotic organisms have two distinct genomes—the nuclear genome and the cytoplasmic genome. Eukaryotic organisms are commonly thought to transmit their cytoplasmic genomes uniparentally, usually from the maternal parent. This form of inheritance should result in only one unique cytoplasmic genome in each individual. However, recent studies have found evidence of more than one unique genome within individuals (referred to as heteroplasmy) in several taxonomic lineages. Heteroplasmy could arise if mutation or recombination create unique subsets of cytoplasmic genomes within cells, or if bi-parental inheritance of the cytoplasmic genome, via paternal leakage, introduces multiple unique cytoplasmic genomes to a zygote. Once heteroplasmy is present, it could be passed to offspring via normal maternal inheritance, or could be lost between generations. Regardless of how it occurs, heteroplasmy warrants study, particularly determining the extent to which heteroplasmy provides evidence of non-maternal inheritance in eukaryotes. This thesis documents the causes and consequences of mitochondrial heteroplasmy in Mimulus guttatus (Phrymaceae), a flowering plant. I used a single PCR-based genetic marker that can distinguish two known unique mitotypes of M. guttatus. I quantified variation in heteroplasmy using quantitative PCR to estimate the ratio of these two mitotypes, both within and among populations and within individuals. I screened open-pollinated seed offspring and the offspring of controlled crosses to look for evidence of paternal leakage, and compared individual mitotype ratios to a series of fitness-related phenotypic traits to assess whether heteroplasmy could be subject to natural selection. First, I found that the occurrence and extent of mitochondrial heteroplasmy varies substantially within and among M. guttatus populations. Second, I also found evidence of within-individual variation in mitotype ratios, where different tissues exhibited different levels of heteroplasmy. Third, my crossing results suggest that the stochastic sorting of alternate mitotypes within plants accounts for most of the cases where mothers and offspring differ in their mitotype ratios, and that paternal leakage occurs very rarely in this species. Finally, I found no evidence of negative effects of heteroplasmy on fitness. Overall, my results indicate that within-plant mitotype variation is an important process in the occurrence of heteroplasmy, and that cytoplasmic markers, particularly in M. guttatus, should be used with care due to the occurrence of the possible confounding effect of heteroplasmy in this and other species.
Advisors/Committee Members: Case, Andrea L.
Subjects: Biology; Evolution and Development; Genetics; Plant Biology
Keywords: heteroplasmy; paternal leakage; vegetative sorting; mitochondria; Mimulus guttatus
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18.
Francl, Jessica M.
Regulation of neuropeptide release in the SCN circadian clock: in vivo assessments of NPY, VIP, and GRP.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2010, Kent State University
► The suprachiasmatic nucleus (SCN) of the hypothalamus is responsible for generating and…
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▼ The suprachiasmatic nucleus (SCN) of the hypothalamus is responsible for generating and maintaining circadian rhythms in mammals. Interneuronal communication in the SCN occurs via neurotransmitter and neuropeptide release, with glutamate, γ-aminobutyric acid (GABA), serotonin (5-HT), neuropeptide Y (NPY), vasoactive intestinal polypeptide (VIP), gastrin-releasing peptide (GRP), and arginine vasopressin (AVP) being the neurochemicals most commonly associated with SCN regulation (reviewed by Reghunandanan and Reghunandanan, 2006). Photic and nonphotic stimuli are received by the SCN and this information is integrated by the SCN, ultimately resulting in a cohesive rhythm output that is entrained to stimulus input. Much data is currently available regarding in vitro actions and rhythmic profiles of release of these SCN neurochemicals through bath application procedures, electrophysiological recordings, immunocytochemistry, and in situ hybridization. However, to date there are few reports on the in vivo release of these agents, and notably neuropeptides from the SCN. The studies performed here used brain microdialysis techniques coupled with sensitive radioimmunoassay to determine the in vivo release over a 24-hr period of three SCN neuropeptides (NPY, VIP, and GRP) in a freely-behaving animal model; additionally, these studies examined the effects of pharmacological agents on the release of these peptides, including both photic and nonphotic stimuli. These experiments are the first to elucidate the in vivo release patterns of NPY, VIP, and GRP from the hamster SCN and provide crucial information regarding the timing of neuropeptide release that can then be used to elucidate possible functions of these peptides within the SCN. The results of these experiments conclude that these neuropeptides are released rhythmically in the SCN and that they are of synaptic origin. It was also shown that these neuropeptides are modulated by photic and nonphotic input signals to the clock. Such information sheds light on the possible functions of these neuropeptides with respect to photic and nonphotic regulation and timing of the mammalian SCN circadian clock.
Advisors/Committee Members: Glass, J. David.
Subjects: Biology
Keywords: circadian rhythm; microdialysis; hamster; neuropeptide; NPY; VIP; GRP
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19.
Ghosh, Rajlakshmi.
Assessment of genetic variation and population differentiation in invasive multiflora rose, Rosa multiflora Thunberg (Rosaceae) in northeastern Ohio.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2009, Kent State University
► SUMMARY In this study, I examined genetic diversity and levels of population…
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▼ SUMMARY In this study, I examined genetic diversity and levels of population differentiation between eight populations of the invasive plant multiflora rose (Rosa multiflora Thunberg Ex. Murray) located in Portage and Summit Counties, in northeastern Ohio. I used six microsatellite marker loci to determine allelic diversity, percent polymorphic loci, and expected and observed heterozygosity. My results show that multiflora rose populations included have moderate levels of genetic variation. I found a total of twenty five alleles in the six microsatellite loci that were examined. On an average, there were 4.16 alleles per locus, but the average number of alleles per locus observed in each population ranged between 1.66 and 3.33. Effective number of alleles ranged between 1.38 and 2.17, indicating variation in allele frequencies among loci. Average observed heterozygosity (HO = 0.15) was less than expected heterozygosity (HE = 0.43) across all but one population. This trend of heterozygosity deficiency and F statistics results indicate significant level of inbreeding in the studied populations. Most of the loci failed to conform to Hardy-Weinberg expectations in all populations indicating forces of evolution interacting. Analysis of molecular variance revealed significant levels of genetic differentiation between populations. Nei’s unbiased estimators of genetic distance range from nearly 0 to 0.59, indicating high genetic differentiation. These findings are then discussed in the light of ecological and historical considerations.
Advisors/Committee Members: Rocha, Oscar.
Subjects: Biology
Keywords: genetic variation, population differentiation, multiflora rose, microsatellite markers, polymorphic
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20.
Grampa, Allison Mary.
Relative Resistin Expression in Normally Cycling and Cystic Rat Ovaries.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2010, Kent State University
► Resistin is a recently identified hormone which may play a role in…
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▼ Resistin is a recently identified hormone which may play a role in insulin resistance, inflammation, human polycystic ovary syndrome, or other physiological states. Resistin protein has been identified and localized in rat testes and the gene for resistin has been identified in mouse ovaries. This led to the hypotheses that resistin mRNA and protein may be present in normally cycling rat ovaries and may differ in ovaries of an animal model of human polycystic ovary syndrome. Rats in the animal model of polycystic ovary syndrome were hypothyroid and treated with hCG to induce ovarian cysts. Resistin mRNA expression was quantified using real-time PCR. Resistin mRNA was present in the ovaries of normally cycling rats in all stages of the estrous cycle, as well as in those of an animal model of human polycystic ovary syndrome. Resistin mRNA did not significantly differ between stages of the cycle. Resistin mRNA was also not different when comparing ovaries of normally cycling rats and cystic ovaries. Resistin protein expression and localization were attempted using Western blot and immunohistochemistry. Resistin protein was not detected with confidence using either of these methods. Until the receptor and signaling pathway for resistin have been elucidated, it will remain difficult to study this molecule.
Advisors/Committee Members: Marcinkiewicz, Jennifer.
Subjects: Biology
Keywords: resistin ovary
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21.
Guinn, Jessie Jr.
Assessment of the Integrative Roles of the Intergeniculate Leaflet in Circadian Timing and Reward Pathways.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2011, Kent State University
► The Intergeniculate leaflet regions (IGL), located in the thalamus, has reciprocal, widespread…
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▼ The Intergeniculate leaflet regions (IGL), located in the thalamus, has reciprocal, widespread interactions with multiple limbic, hindbrain and forebrain areas implicated in circadian rhythm regulation. First discovered by Hickey and Spear in 1976, it is thought to integrate inputs from these regions into a phase-resetting signal to the suprachiasmatic nucleus (SCN) circadian clock mediated by neuropeptide Y (NPY) release from geniculohypothalamic tract (GHT) terminals. Included in the diversity of inputs to the IGL is a dense serotonergic projection from the dorsal raphe nucleus (DRN) (Meyer-Bernstein and Morin, 1996). Circadian phase-shift eliciting electrical stimulation of the DRN or novel wheel exposure induces 5-HT release in the IGL (Grossman et al., 2004). Also, Blasiak and Lewandowski (2003 & 2004) showed via electrophysiological recordings that 5-HT and GABA are modulatory on IGL neuronal activity. Bilateral injection of 8-OH-DPAT into the IGL causes phase-advances in wheel-running activity (Challet et al., 1998) and systemic 8-OH-DPAT induces Fos expression in IGL cells (Grossman, 2006). Reward stimuli act on a neural network consisting of the mesolimbic dopamine pathway. This pathway includes dopaminergic neurons in the ventral tegmental area (VTA) and reciprocal interaction with the mesopontine system that includes cholinergic neurons of the pedunculopontine tegmentum (PPT) and the laterodorsal tegmentum (LDT). The IGL receives input from this system that registers the reinforcing effects of natural and drug-related reward. Notably, this non-photic input is cholinergic in nature (Horowitz et al., 2004; Vrang et al., 2003). Thus, the IGL serves as a major integrative hub by processing information from numerous sites to regulate circadian clock timing. Despite this information, critical questions remain concerning the neurophysiological nature of signal integration in the IGL, and how this modulates NPY neuronal activity. To address this knowledge gap, the following experiments were undertaken to assess IGL-NPY neurochemical regulation using bilateral microinjections into both IGLs, evaluation of circadian locomotor rhythmicity and sensitive microdialysis-RIA measurements of in vivo NPY release in the SCN. In regards to reward input to the IGL, experiments were done to investigate the regulatory role of the reward network in circadian timekeeping. This was accomplished by novel wheel exposure, immunohistochemistry, acute electrical stimulation of the VTA and PPT, bilateral microinjection into the IGLs and evaluation of circadian locomotor rhythmicity.
Advisors/Committee Members: Glass, J. David.
Subjects: Behavioral Sciences; Biology; Biomedical Research; Neurobiology; Neurosciences; Physiology
Keywords: intergeniculate leaflet; suprachiasmatic nucleus; reward; cholinergic; circadian; cocaine; nonphotic; microdialysis; microinjection; syrian hamster; NPY; neuropeptide Y; phase shift; stereotaxic surgery
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22.
Hausman, Constance Elizabeth.
The Ecological Impacts of the Emerald Ash Borer (Agrilus Planipennis): Identification of Conservation and Forest Management Strategies.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2010, Kent State University
► The introduction of exotic species is the inevitable consequence of an expanding…
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▼ The introduction of exotic species is the inevitable consequence of an expanding global society that relies heavily on international trade of goods and services. These introduced species have negative effects on biodiversity and disrupt native communities. In fact, the spread of non-native species is the second greatest threat to the loss of biodiversity next to habitat destruction. The emerald ash borer (EAB), Agrilus planipennis Fairmaire (Buprestidae), is a recent example of an exotic forest pest species. EAB completes its life cycle on ash trees (Fraxinus spp.) including larvae feeding on cambium tissue which interferes with water and nutrient translocation. Once ash trees become infested with EAB, mortality is >99%. This dissertation was initiated after EAB was discovered and attempts to understand how EAB affects long-term forest community dynamics in order to provide practical applied conservation strategies. These research projects are designed to identify the ecological impacts of EAB and to determine long-term community changes to native deciduous forests. The research objectives are: (1) to identify consequences of EAB eradication efforts, (2) to determine altered community composition under different disturbance intensities (tree removal management recommendations) and (3) to design effective ex situ conservation protocols for future ash tree preservation. EAB causes a disturbance to native forest by creating large light gaps through ash tree dieback; yet, EAB eradication efforts magnified the scale of disturbance through time and space which facilitated the establishment of invasive plant species. The tracked vehicles used during eradication also caused significant soil compaction. Management efforts applied to EAB-infested forests should prioritize appropriate tree removal techniques to minimize the disturbance to the surrounding community. Ash stands in close proximity to roads or edges, or near established invasive populations may benefit from proactive removal of invasive species. This research contributes to ash conservation efforts by providing a guideline for ex situ collection methods. By understanding diversity and spatial genetic structure of green ash (Fraxinus pennsylvanica), a seed collection protocol has been constructed that optimizes the likelihood of capturing all alleles in a population while minimizing collection efforts. This cumulative research provides effective forest management recommendations and prioritizes ash conservation.
Advisors/Committee Members: Rocha, Oscar.
Subjects: Biology; Botany; Ecology; Environmental Management; Forestry; Molecular Biology; Plant Biology
Keywords: Emerald ash borer; EAB; eradication; invasive species; disturbance; light gaps; soil compaction; Fraxinus pennsylvanica; ash; genetic structure; germplasm
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23.
Helfinstine, Shannon L.
The Detection and Control of Bacillus Endospores.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2007, Kent State University
► The deliberate dissemination of anthrax spores through the US Postal System in…
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▼ The deliberate dissemination of anthrax spores through the US Postal System in 2001 resulted in mail decontamination using electron beam (EB) accelerators, and the realization for the need for faster, more reliable, and inexpensive detection systems. There is paucity of scientific literature addressing the questions of (1) how to successfully detect Bacillus spores in an efficient and cost-effective manner, and (2) how accelerated electrons effectively control Bacillus spores. To address these questions Bacillus atrophaeus (a traditional anthrax surrogate) was used to study a lyotropic chromonic liquid crystal (LCLC) biosensing technology and to evaluate EB irradiation as a sporicide. For the biosensor, B. atrophaeus spores and anti-B. atrophaeus antibodies were mixed into a LCLC and added to specially created glass slides. LCLC distortions in the slides (caused by the spores and antibodies clumping together within the liquid crystal) were viewed with polarizing microscopy as white spots against a black background and quantified. To answer the second question of how spores are controlled with EB irradiation, the D 10value (dose required to reduce a population by 90%) for B. atrophaeus spores was determined. Spores were dried onto filter papers and placed within small paper coin envelopes and irradiated over a range of doses to determine the dose required to kill 10 8spores. Surviving spores were counted using the standard plate count method. To more thoroughly address the effectiveness of spore control using EB radiation, DNA breakage as a function of increasing EB dose was measured using the agarose gel electrophoresis technique on extracted spore DNA. Also, EB induced damage of the spore outer structures was evaluated using flow cytometry to measure uptake of two fluorescent dyes. These experiments resulted in the following findings: (1) the LCLC biosensor was able to detect Bacillus spores with a detection sensitivity at 105 spores ml-1, (2) EB irradiation dose-dependently kills B. atrophaeus spores in simulated mail, with a D 10of 1.53 kGy, and (3) spore structure and DNA damage is also dose-dependent.
Advisors/Committee Members: Woolverton, Christopher J.
Subjects: Biology, Microbiology
Keywords: Bacillus; spores; electron beam irradiation; anthrax; liquid crystals; detection
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24.
Hovatter, Stephanie R.
THE EFFECTS OF BIOTIC AND ABIOTIC SOIL CHARACTERISTICS ON POPULATION SIZE VARIATION OF LOBELIA SIPHILICITA.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2008, Kent State University
► Populations of plants can vary dramatically in the number of individuals they…
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▼ Populations of plants can vary dramatically in the number of individuals they contain. Small populations are often at greater risk of extinction, making it important to understand why some populations consist of hundreds of plants while others contain fewer than twenty. Factors that affect germination, seedling establishment, growth, or survival will likely have a significant effect on population size. Because plants are continually in contact with the soil environment, such factors likely include interactions with soil microbes, such as fungi, and aspects of soil chemistry and composition. Lobelia siphilitica, an herbaceous perennial plant native to the eastern United States, exhibits a high degree of variation in population size. I sampled soils from 14 populations across Ohio and West Virginia, ranging in size continuously from 30-330 individuals. I have conducted two detailed studies addressing regional variability in soil properties, microbial community composition, and plant-microbe feedback that may explain plant population size variation. The first deals with spatial patterns of soil microbial community composition, and how this organization is affected the presence or absence of this plant species, soil characteristics, and geographic location (Chapter 2). I found that microbial communities found at different microhabitats within the same location can be structured quite differently, and that this may in fact be contributing to the actual soil effect. The second study examines plant-soil feedback and its potential to explain geographic variation in population size in L. siphilitica (Chapter 3). I found regional-scale variation in negative feedback on seed germination, growth, and survival that is likely mediated by biotic components in the soils. The strength of negative feedback was strongly positively correlated with plant population size, suggesting that the combination of negative effects on these plant success traits likely results in the geographic variation that is seen in population size of this particular species. Overall, my results indicate that regional-scale variation in negative feedback is likely mediated by biotic components in the soils, and that this may have severe consequences for low abundance species.
Advisors/Committee Members: Case, Andrea.
Keywords: SOIL; Plants; POPULATION SIZE; siphilitica; seeds; germination; seed source
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25.
Kapusinski, Douglas John.
Factors Affecting Invertebrate and Fish Communities in Coastal Wetlands of the Great Lakes.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2012, Kent State University
► I examined differences in fish and benthic invertebrate communities in open Great…
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▼ I examined differences in fish and benthic invertebrate communities in open Great Lakes coastal wetlands versus impounded wetlands. Open Great Lakes coastal wetlands (GLCW) are wetlands along the Laurentian Great Lakes that are connected to the lakes and are influenced by lake water level fluxuations. These connections may be permanent or may only be present when lake water levels are high. Many fish species in the Great Lakes migrate into these open coastal wetlands to breed and feed on abundant invertebrate food resources. The GLCW are also important habitats for unionid mussels, that persist in these refuges even though they have been nearly extirpated form the Great Lakes. Unionids may also provide a unique microhabitat for epizoic invertebrates that live attached to their shells. Migratory shorebirds also feed on invertebrates in these wetlands during their spring and fall migrations. Thus, I also examined if fish and migratory shorebird preyed on similar invertebrate taxa in open coastal wetlands. My research was performed at Ottawa National Wildlife Refuge in Oak Harbor, OH. This site includes a coastal wetland along Lake Erie, as well as impounded wetlands, where water levels are managed for bird habitats and to control invasive species. In my first study, I found that both fish and invertebrate communities differed between open coastal wetlands and impounded wetlands, probably due factors such as predation, competition and abiotic conditions. For example, invertebrate community differed among water depths in open coastal wetlands but not in impounded wetlands. I also used exclosures to test if fish and shorebirds impact benthic and epizoic invertebrate densities and diversities. I found that fish reduce total invertebrate density and diversity. However, some invertebrate taxa increased after competitively dominant taxa were reduced. I found no impact of shorebird predation on benthic invertebrates in these areas. I also found that common carp were an important predator of benthic invertebrates. They also reduced epizoic invertebrates (e.g., zebra mussels) on native unionid mussels.
Advisors/Committee Members: de Szalay, Ferenc A.
Subjects: Animal Sciences; Aquatic Sciences; Biology; Ecology; Entomology; Environmental Science; Environmental Studies; Freshwater Ecology; Organismal Biology; Zoology
Keywords: benthic invertebrates, Lake Erie, marsh, Great Lakes Coastal Wetland, shorebirds, common carp, Cyprinus carpio, Dreissenidae, Driessena polymorpha, Unionidae, Quadrula quadrula, Chironomidae, Oligochaeta, Sphaeriidae, Non-metric Multidimensional Scaling
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26.
Kaur, Gagandeep.
Phase Regulation of the SCN Circadian Clock: Serotonergic and Neuropeptidergic Mechanisms.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2009, Kent State University
► Timing of the mammalian circadian clock, the suprachiasmatic nucleus (SCN) is regulated…
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▼ Timing of the mammalian circadian clock, the suprachiasmatic nucleus (SCN) is regulated by photic and nonphotic entraining inputs. Photic inputs reach the SCN from the retinohypothalamic tract (RHT) utilizing glutamate as neurotransmitter, which activates the retinorecipient cells of the SCN in part by release of gastrin releasing peptide (GRP). Nonphotic inputs reach the SCN from the raphe nuclei and the intergeniculate leaflet utilizing serotonin (5-HT) and neuropeptide Y (NPY) as neurotransmitters respectively. Efferent signaling of the SCN to target areas involves arginine vasopressin (AVP). Brief (~2 day) constant light exposure (LLb), significantly enhances phase resetting responses to 5-HT1A,7 agonist 8-OH-DPAT and other nonphotic stimuli. The present study was undertaken to determine if LLb exposure can amplify phase resetting responses to endogenous 5-HT and accelerate re-entrainment responses to large magnitude phase advance shifts of the light/dark (LD) cycle. Endogenous 5-HT activity was increased by systemic administration of 5-HT precursor L-tryptophan and reuptake inhibitor fluoxetine. In hamsters exposed to LLb phase shifting responses to stimulated endogenous 5-HT were significantly enhanced compared to those under LD. LLb exposure also had significant potentiating effect on rhythm re-entrainment response to 8-OH-DPAT. Hamsters exposed to LLb and 8-OH-DPAT re-entrained faster to a 10 hour phase advance shift of the LD cycle compared to the vehicle or LD controls. Further, analysis of distinct daily rhythms of the SCN peptidergic activity and effect of serotonergic activation on them was studied. Sensitive microdialysis-radioimmunoassay procedure was used to explore the regulatory role of 5-HT on AVP and GRP release from the SCN. In hamsters housed under 14:10 LD, AVP exhibited daily fluctuations of release with levels increasing during the morning to peak around mid subjective day. This pattern persists under constant darkness confirming the circadian nature of the AVP release. Synaptic release was confirmed by reverse microdialysis with calcium channel blockers and depolarizing agents. Reverse microdialysis with 8-OH-DPAT during the subjective day, significantly suppressed the SCN GRP release but had little effect on AVP. Overall, potentiation of serotonergic phase resetting response by LLb offers a potential approach for treatment of circadian related desynchronies. The interactions between serotonergic and peptidergic systems of the SCN are important in determining the phase of the SCN activity in response to LLb and other stimuli.
Advisors/Committee Members: Glass, J. David.
Subjects: Behaviorial sciences; Biology; Neurology
Keywords: suprachiasmatic nucleus, serotonin, nonphotic, arginine vasopressin, hamster
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27.
Kennedy, Emmalisa.
Effects of control of the invasive plant, Phragmites australis, on microbes and invertebrates in detritus.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2008, Kent State University
► Emergent plant litter is a major source of energy and carbon in…
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▼ Emergent plant litter is a major source of energy and carbon in wetland food webs. Detritus and the associated microbes are eaten by invertebrates, thereby transferring the carbon and energy to higher trophic levels. Monocultures of an invasive common reed, Phragmites australis, can alter wetland food webs and decrease native plant diversity. Therefore, stands are often controlled by cutting and/or herbiciding. The processes of decomposition were studied using leaves of herbicided and non-herbicided Phragmites and non-herbicided native wool grass, Scirpus cyperinus, using litterbags in wetland mesocosms. Leaf mass loss, percent organic content, C:N ratios, fungal biomass, bacterial numbers and biomass, and invertebrate community composition (total numbers, abundance of functional feeding groups and dominant taxa, richness) were examined on ten dates over the course of 293 days. There were no differences in invertebrate communities or most chemical characteristics between herbicided and non-herbicided Phragmites leaf litter, and both litter types decayed at similar rates (0.0047 k-1 and 0.0051 k-1, respectively). However, herbicided Phragmites litter had higher fungal and bacterial biomass than non-herbicided Phragmites litter. In contrast, Scirpus litter decayed much more slowly (0.0029 k-1) and had higher organic content remaining than either Phragmites litter. At the end of the study, over 44% of the Scirpus litter remained but only 13 - 14% of Phragmites litter remained. Significant differences were found in microbial communities between Scirpus and Phragmites litter, where Phragmites litter generally had higher fungal and bacterial biomass. Invertebrate richness was also higher on Phragmites than Scirpus litter. Furthermore, there were non-significant trends that total invertebrates, detritivores and collector-gatherers were higher on Phragmites than Scirpus litter by the last sampling date (25 May 2007). Principle components analysis also showed high positive correlation between fungal biomass and invertebrate richness. Collectively, these results indicate that the use of herbicide to control Phragmites may not significantly alter decomposition processes or the associated invertebrate community compared to non-herbicided Phragmites stands. Furthermore, although dense stands of the invasive Phragmites can decrease overall wetland plant diversity, numbers and diversity of detritivorous invertebrates on the litter, invertebrates on Phragmites leaf litter may be as high as those occurring on native plants that have slow decay rates.
Advisors/Committee Members: Leff, Laura.
Subjects: Biology; Botany; Ecology; Entomology; Environmental science; Microbiology
Keywords: Phragmites australis; Scirpus cyperinus; glyphosate; microbes; ergosterol; invertebrates
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28.
Kirkpatrick, Heather.
The Ecological Influence of the Non-Indigenous Zooplankter Eubosmina coregoni in Lake Ecosystems.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2011, Kent State University
► Invasive non-indigenous (NI) zooplankton are a concern in aquatic systems since they…
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▼ Invasive non-indigenous (NI) zooplankton are a concern in aquatic systems since they can prey on native species, outcompete natives for resources, parasitize or host parasites that negatively affect natives, and cause shifts in native zooplankton communities that can cause changes in the trophic structure of lakes. Eubosmina coregoni is a NI zooplankter that is native to lakes in Northern Europe and Russia and has invaded the Laurentian Great Lakes and inland lakes within 100 km of the Great Lakes. This study used a combination of literature review and experimental manipulations to better understand the factors involved in the establishment of Eubosmina coregoni in the Twin Lakes (Portage County, OH) and the consequences of its presence in lake ecosystems. Historical data collected from the Twin Lakes show that E. coregoni was discovered in East Twin Lake in 1976, four years after surrounding septic tanks were diverted and connected to main municipal sewer systems, and one year after an aluminum sulfate treatment applied to West Lake. E. coregoni has since spread to West Twin Lake and has become the most dominant zooplankter in both these lakes. Experimental trials involving two common predators in the Twin Lakes, Chaoborus punctipennis and Lepomis macrochirus, and mixtures containing E. coregoni and B. longirostris, a close relative of E. coregoni and native zooplankter in the Twin Lakes, were performed to assess predator preference. C. punctipennis significantly preferred the native B. longirostris over the NI E. coregoni in every trial (p < 0.001), whereas Lepomis macrochirus did not show any preference for either species (p > 0.05). Measurements were also performed on the carapace height and length of both E. coregoni and B. longirostris to determine the presence of cyclomorphosis, a type of phenotypic plasticity that can possibly act as an anti-predator defense. Seasonal differences in the proportion of height to length were found in E. coregoni but not B. longirostris, and these differences occurred during the summer months when C. punctipennis densities were at their highest. This study concludes that a combination of the lake restoration techniques performed on the Twin Lakes, C. punctipennis preference for B. longirostris over E. coregoni, and possible cyclomorphosis in E. coregoni were all factors contributing to the successful establishment of this species in the Twin Lakes.
Advisors/Committee Members: Bade, Darren.
Subjects: Aquatic Sciences
Keywords: zooplankton; cyclomorphosis; Twin Lakes; Eubosmina coregoni; Bosmina longirostris; Chaoborus punctipennis
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29.
Knoch, Megan E.
Short Term Exposure to Light Potentiates Phase Shifting to Nonphotic Stimuli in the Syrian Hamster.
Degree: PhD, College of Arts and Sciences / Department of Biological Sciences, 2005, Kent State University
► The mammalian circadian clock is located within the suprachiasmatic nuclei (SCN) of…
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▼ The mammalian circadian clock is located within the suprachiasmatic nuclei (SCN) of the hypothalamus and synchronizes organisms to their external environment allowing for the coordination of physiological functions within the body. Synchronization, or entrainment of circadian rhythms of locomotor activity, core body temperature and gene expression occurs in response to specific stimuli, which may be photic (consisting of the ambient light-dark cycle) or nonphotic. In Syrian hamsters, nonphotic stimuli including induced activity, social interaction and sleep deprivation result in phase shifts which are characteristic alterations in the animals’ pattern of locomotor activity. The neurotransmitters neuropeptide Y (NPY) and serotonin (5-HT) induce phase shifts very similar to a nonphotic stimulus when applied in vitro or in vivo. Furthermore, 5-HT release peaks at the onset of locomotor activity and increases transiently during periods of sleep deprivation. To date, several studies argue both for and against a role for 5-HT in nonphotic entrainment. Regardless, potent phase-resetting actions of 5-HT have been observed under conditions where serotonergic postsynaptic response is enhanced in vivo. I hypothesized that nonphotic phase-resetting is influenced not only by the circadian phase of application, but by the degree of serotonergic activity preceding the stimulus. In the current experiments, adult male hamsters were exposed to brief duration (1-3 days) of constant light (LL), which resulted in the suppression of SCN 5-HT release. Additionally, a potentiation of phase-shifting to a serotonergic stimulus was observed in a phase- and dose-dependent manner, and could be attenuated by artificially reintroducing 5-HT into the SCN. A series of pharmacological trials were undertaken in an attempt to determine which 5-HT receptors mediate the effects of LL on 5-HT phase-resetting, but the results were inconclusive. Despite being unable to identify the target 5-HT receptor, results from this study suggest that the circadian clock is sensitive to serotonergic stimuli subsequent to LL exposure.
Advisors/Committee Members: Glass, David J.
Subjects: Biology, Neuroscience
Keywords: circadian, suprachiasmatic nucleus, sertonin, phase-resetting, hamster
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30.
Linley, Moreland.
INVOLVEMENT OF TISSUE-TYPE PLASMINOGEN ACTIVATOR IN THE REGULATION OF CIRCADIAN RHYTHMS.
Degree: MS, College of Arts and Sciences / Department of Biological Sciences, 2010, Kent State University
► Tissue-type plasminogen activator (tPA), a serine protease traditionally known for its regulation…
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▼ Tissue-type plasminogen activator (tPA), a serine protease traditionally known for its regulation of fibrinolytic activity in the bloodstream, is also responsible for generation of mature brain-derived neurotrophic factor (mBDNF) in the central nervous system. Since mBDNF is critical to photic entrainment and normal phase-shifting behavior in the suprachiasmatic nucleus (SCN), we monitored the circadian phase shift response to light during early and late subjective night in mice deficient in tPA (tPAKO) in comparison to wildtype (WT) mice. tPAKO mice did not exhibit differential phase-shifting behavior during early or late subjective night in comparison to WT mice. To assess whether entrainment to food was altered in the knockout mice, tPAKO and WT mice were put on a restricted feeding schedule on a light-dark cycle to monitor the behavioral response to a nonphotic cue as well as expression of food anticipatory activity (FAA). Since tPAKO mice are deficient in long-term potentiation and memory, we hypothesized that tPAKO mice would show decreased FAA as the animals would have difficulty learning the time of food restriction. Contrary to our hypothesis, tPAKO mice exhibited significantly enhanced FAA in comparison to WT mice, which gradually decreased over a span of 10 days. The locomotor activity of tPAKO and WT mice were also monitored during a 48hr fast. Since no significant difference in activity between genotypes was observed during the 48hr fast, it appears that the enhanced FAA of tPAKO mice is specific to the restricted feeding schedule and not just a result of reduced food availability. Expression of central and peripheral clock genes in the SCN and liver of tPAKO and WT mice were assayed during the phase of FAA (ZT5). Clock was suppressed in the liver during restricted feeding in both genotypes, while Per1 and Per2 were increased. Per2 expression was also significantly higher in tPAKO mice than WT mice during restricted feeding. In the SCN, there was no significant difference in Per1 and Per2 expression between genotype or feeding regimen, consistent with previous reports of SCN activity being unaffected by a restricted feeding regimen. A significant interaction was observed in that Clock expression was significantly higher in WT mice than tPAKO mice during ad libitum feeding. The present data clearly indicate a role for tPA modulation of FAA, and further research will be necessary to identify the mechanisms through which tPA modulates central structures and influences peripheral feedback during restricted feeding.
Advisors/Committee Members: Mintz, Eric.
Subjects: Biology
Keywords: tissue-type plasminogen activator, food anticipatory activity, food restriction, circadian
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