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Ric-8a Catalyzes Guanine Nucleotide Exchange On G Alphai1 Bound To The Gpr/Goloco Exchange Inhibitor Ags3, Celestine J. Thomas, Gregory G. Tall, Anirban Adhikari, Stephen R. Sprang

Biological Sciences Faculty Publications

Microtubule pulling forces that govern mitotic spindle movement of chromosomes are tightly regulated by G-proteins. A host of proteins, including Galpha subunits, Ric-8, AGS3, regulators of G-protein signalings, and scaffolding proteins, coordinate this vital cellular process. Ric-8A, acting as a guanine nucleotide exchange factor, catalyzes the release of GDP from various Galpha.GDP subunits and forms a stable nucleotide-free Ric-8A:Galpha complex. AGS3, a guanine nucleotide dissociation inhibitor (GDI), binds and stabilizes Galpha subunits in their GDP-bound state. Because Ric-8A and AGS3 may recognize and compete for Galpha.GDP in this pathway, we probed the interactions of a truncated AGS3 (AGS3-C; containing only …

Distinct Contributions Of Model Masp1 And Masp2 Like Peptides To The Mechanical Properties Of Synthetic Major Ampullate Silk Fibers As Revealed In Silico, Amanda E. Brooks, Shane R. Nelson, Justin A. Jones, Courtney Koenig, Michael Hinman, Michael Hinman, Shane Stricker, Randolph V. Lewis

Biology Faculty Publications

All characterized major ampullate silks from orb-web weaving spiders are composites of primarily two different proteins: MaSp1 and MaSp2. The conserved association of MaSp1 and MaSp2 in these spider species, the highly conserved amino acid motifs, and variable ratios of MaSp1 to MaSp2 demonstrate the importance of both MaSp1 and MaSp2 to the strength and elasticity of the fiber. Computer simulated mechanical tests predicted differing roles for MaSp1 and MaSp2 in the mechanical properties of the fibers. Recombinant MaSp1 and MaSp2 proteins were blended and spun into fibers mimicking the computer-simulated conditions. Mechanical testing verified the differing roles of MaSp1 …

The Effects Of Indirubin Derivitives On Gene Expression And Cellular Functions In The Murine Macrophage, Abigail Babcock

All Dissertations

Indirubin is the active ingredient in the ancient herbal remedy, Danggui Longhui Wan, which is used as an anti-leukemic, anti-inflammatory, and detoxification treatment. Indirubin-3'-monoxime (IO) is the most widely studied of the indirubin derivatives. Most have been shown to inhibit cyclin-dependent kinases and glycogen synthase kinases, triggering cell cycle arrest and apoptosis with different levels of activity depending on the particular structure. These kinases inhibited by indirubin(s) play key roles in cellular proliferation and immune functions, therefore synthetic indirubins may have significant applications as therapeutic agents for cancer, inflammation, and neurological diseases.
Indirubin is also a potent aryl hydrocarbon receptor …

The Leaf Ionome As A Multivariable System To Detect A Plant's Physiological Status, Ivan R. Baxter, Olga Vitek, Brett Lahner, Balasubramaniam Muthukumar, Monica Borghi, Joe Morrissey, Mary Lou Guerinot, David E. Salt

Dartmouth Scholarship

The contention that quantitative profiles of biomolecules contain information about the physiological state of the organism has motivated a variety of high-throughput molecular profiling experiments. However, unbiased discovery and validation of biomolecular signatures from these experiments remains a challenge. Here we show that the Arabidopsis thaliana (Arabidopsis) leaf ionome, or elemental composition, contains such signatures, and we establish statistical models that connect these multivariable signatures to defined physiological responses, such as iron (Fe) and phosphorus (P) homeostasis. Iron is essential for plant growth and development, but potentially toxic at elevated levels. Because of this, shoot Fe concentrations are …

Identifying And Characterizing Arabidopsis Jasmonate Signaling Components Manipulated By Pseudomonas Syringae, Neva Laurie-Berry

Arts & Sciences Graduate Student Theses and Dissertations

Jasmonate signaling is critical for susceptibility of Arabidopsis thaliana to the bacterial pathogen Pseudomonas syringae, as demonstrated by the reduced susceptibility of coil mutant plants. The infection responses of another jasmonate-insensitive mutant, jinl, had previously been unknown. This work demonstrates that susceptibility to P. syringae requires activity of the transcription factor JTN1/MYC2. Reduced susceptibility correlates with reduced sensitivity to the P. syringae phytotoxin coronatine, a molecular mimic of the endogenous jasmonate JA-Ile. The reduced susceptibility of jinl mutant plants correlates with increased salicylic acid (SA)-dependent signaling. Analysis of jinl plants carrying the sidl mutation, resulting in decreased S A synthesis …

Limited Native Plant Regeneration In Novel, Exotic-Dominated Forests On Hawai’I, Joseph Mascaro, Kristen K. Becklund, R. Flint Hughes, Stefan A. Schnitzer

Biological Sciences Faculty Research and Publications

Ecological invasions are a major driver of global environmental change. When invasions are frequent and prolonged, exotic species can become dominant and ultimately create novel ecosystem types. These ecosystems are now widespread globally. Recent evidence from Puerto Rico suggests that exotic-dominated forests can provide suitable regeneration sites for native species and promote native species abundance, but this pattern has been little explored elsewhere. We surveyed 46 sites in Hawai’i to determine whether native species occurred in the understories of exotic-dominated forests. Native trees smaller than 10 cm in diameter were absent in 28 of the 46 sites and rare in …

Trypanosoma Cruzi In Wild Raccoons And Opossums From Kentucky, Brian Chad Groce

Masters Theses & Specialist Projects

Only 6 autochthonous cases of human Chagas disease have been documented in the U.S.A., however, as many as 5% of immigrants from Latin America may be infected with the etiologic agent, Trypanosoma cruzi. The parasite has been isolated from a variety of wild mammals, particularly in the southeastern region of the U.S.A. The goal of our study was to determine if the sylvatic cycle of T. cruzi infection occurs in Kentucky, and, if present, to assess the prevalence of infection in Warren and Barren counties. Raccoons and opossums were live-trapped between June and December, 2007. Animals were anesthetized with …

Teaching Mendelism, William D. Stansfield

Biological Sciences

No abstract provided.

Conversion Of Traditional Observation-Based Botany Labs To Investigative Inquiry Learning, Hajara Mahmood

Masters Theses & Specialist Projects

“Tell me and I forget, show me and I remember, involve me and I understand.” - Chinese Proverb. Involvement in learning implies possessing skills and attitudes that permit students to seek resolutions to questions and issues while constructing new knowledge.

Low enrollment in Plant Biology and Diversity and upper level plant science courses has been noticed at Western Kentucky University. In addition, graduating students performed below the national average on the senior assessment examination in the area of botany content knowledge offered by WKU’s Biology Department. This may be due to the fact that observation-based botany has been taught in …

I. Vh Gene Transcription Creates Stabilized Secondary Structures For Coordinated Mutagenesis During Somatic Hypermutation, Barbara E. Wright, Karen H. Schmidt, Michael F. Minnick, Nick Davis

Biological Sciences Faculty Publications

During the adaptive immune response, antigen challenge triggers a million-fold increase in mutation rates in the variable-region antibody genes. The frequency of mutation is causally and directly linked to transcription, which provides ssDNA and drives supercoiling that stabilizes secondary structures containing unpaired, intrinsically mutable bases. Simulation analysis of transcription in VH5 reveals a dominant 65nt secondary structure in the non-transcribed strand containing six sites of mutable ssDNA that have also been identified independently in human B cell lines and in primary mouse B cells. This dominant structure inter-converts briefly with less stable structures and is formed repeatedly during transcription, due …

Ii. Correlations Between Secondary Structure Stability And Mutation Frequency During Somatic Hypermutation, Barbara E. Wright, Karen H. Schmidt, Nick Davis, Aaron T. Hunt, Michael F. Minnick

Biological Sciences Faculty Publications

The role of secondary structures and base mutability at different levels of transcription and supercoiling is analyzed in variable region antibody genes VH5, VH94 and VH186.2. The data are consistent with a model of somatic hypermutation in which increasing levels of transcription and secondary structure stability correlate with the initial formation of successive mutable sites. Encoded differences exist in stem length and the number of GC pairs at low versus high levels of transcription in CDRs. These circumstances simplify the complexities of coordinating mutagenesis by confining this process to each mutable site successively, as they form in response to increasing …

Structure Of A Signal Transduction Regulator, Rack1, From Arabidopsis Thaliana, Hemayet Ullah

Department of Biology Faculty Publications

The receptor for activated C-kinase 1 (RACK1) is a highly conserved WD40 repeat scaffold protein found in a wide range of eukaryotic species from Chlamydymonas to plants and humans. In tissues of higher mammals, RACK1 is ubiquitously expressed and has been implicated in diverse signaling pathways involving neuropathology, cellular stress, protein translation, and developmental processes. RACK1 has established itself as a scaffold protein through physical interaction with a myriad of signaling proteins ranging from kinases, phosphatases, ion channels, membrane receptors, G proteins, IP3 receptor, and with widely conserved structural proteins associated with the ribosome. In the plant Arabidopsis thaliana, RACK1A …

Intrafeather And Intraindividual Variation In The Stable-Hydrogen Isotope (Δd) Content Of Raptor Feathers, Adam D. Smith, Kara Donohue, Alfred M. Dufty Jr.

Biology Faculty Publications and Presentations

Stable-hydrogen isotope ratios (deuterium:protium; δD) in feathers enable researchers to evaluate patterns of avian movement and to estimate the source areas of migratory birds. However, variation in feather δD remains inadequately described, thus confounding inferences of avian movement and origin. We assessed variation within a feather and among feathers within and between tracts in three species of immature raptors. Within contour feathers, measurements of δD increased from a distal section to an adjacent, proximal section; the magnitude of δD increase varied with raptor species. Furthermore, contour and flight feathers differed systematically in their δD content. Two explanations for intrafeather and …

The Effects Of An Artifically Elevated Thermal Environment And Seasonal Acclimatization On The Thermal Tolerance Of The Western Mosquitofish, Gambusia Affinis, Rebbekah Watson

Biology Theses - Archive

Gambusia affinis, the western mosquitofish, is a very hardy, live-bearing fish that has invaded freshwater habitats worldwide. The success of the western mosquitofishs' invasion is due to its reproductive capabilities and ability to tolerate a wide range of temperatures. The mosquitofish can inhabit waters as low as 0°C and higher than 40°C. Because of this species' eurythermicity, questions have been raised regarding the impact of artificially heated environments on its thermal tolerance limits and whether its thermal tolerance limits are consistent across seasons. Past studies have shown that mosquitofish populations inhabiting hot ponds receiving thermal effluents at steam-electric power stations …

Comparative Thermal Biology And Associated Niche Differentiation Among The Five-Lined Skinks, Charles Matthew Watson

Biology Dissertations - Archive

Three species of five-lined skinks (Plestiodon fasciatus, P. laticeps, and P. inexpectatus) occur in regional sympatry across much of the Southeastern United States. These closely-related species, at one or more levels of development, all exhibit a like phenotype and a high amount of prey resource overlap as documented by published data. Under competitive exclusion hypotheses, these species should therefore not locally co-occur. This study confirms, through analysis of habitat type and canopy cover at the point of capture, that P. inexpectatus and P. fasciatus do not typically inhabit the same forest habitat. In fact, where their ranges overlap, P. fasciatus …

Patterns Of Body And Tail Length And Body Mass In Sciuridae, Virginia Hayssen

Biological Sciences: Faculty Publications

For squirrels, physical size varies with ancestry, locomotion, and sex. Body length has little variation associated with subfamilies or tribes but varies significantly among genera within tribes. Thus, patterns in body size among genera represent more recent evolutionary pressures. Flying squirrels weigh less than similarly sized tree or ground squirrels but ecological profile and ancestry are confounded for flying squirrels. Tail length has clear relationships with ecological profile in squirrels. Tail length is shorter in ground squirrels, longer in tree squirrels, and longest in flying squirrels. In addition, in arboreal squirrels, females have longer tails, relative to body length, than …

No Evidence For Trade-Offs: Centaurea Plants From America Are Better Competitors And Defenders, Wendy M. Ridenour, Jorge M. Vivanco, Yulong Feng, Jun-Ichiro Horiuchi, Ragan M. Callaway

Biological Sciences Faculty Publications

The natural enemies hypothesis has led to a number of ideas by which invaders might evolve superior competitive ability. In this context, we compared growth, reproduction, competitive effect, competitive response, and defense capabilities between invasive North American populations of Centaurea maculosa and populations in Europe, where the species is native. We found that Centaurea from North America were larger than plants from European populations. North American Centaurea also demonstrated stronger competitive effects and responses than European Centaurea. However, competitive superiority did not come at a cost to herbivore defense. North American plants were much better defended against generalist insect …

Characterization Of Kaposi's Sarcoma-Associated Herpesvirus Orf11 As A Possible Dutpase, Christina N. Ramirez

Seton Hall University Dissertations and Theses (ETDs)

A dUTPase is a crucial enzyme that hydrolyzes dUTP to dUMP. This reaction prevents the mutagenic or lethal misincorporation of uracil into DNA. For that reason, the enzyme is required for efficient DNA replication. Previous studies have shown that has ORFl l dUTPase-like motifs and thus may be a dUTPase. Generally, gammaherpesviruses contain six characteristic dUTPase motifs. In particular ORFl 1 and contains motifs 1, 2, 4, 6. While the characteristic motifs of gamroaberpesviruses include motifs 1, 2, 3, 4, 5, and 6, the number of dUTPase-like motifs in ORFl 1 's protein sequence is substantial. Thus, ORFl 1 may …

Phyllodictyon Robustum (Setchell Et Gardner) Comb. Nov. (Siphonocladales, Chlorophyta), A Morphologically Variable Species From The Tropical Pacific Coast Of America, Frederik Leliaert, Brian Wysor, Heroen Verbruggen, Caroline Vlaeminck, Olivier De Clerck

Arts & Sciences Faculty Publications

The systematic positions of Cladophoropsis robusta and Willeella mexicana, both occurring along the tropical Pacific coast of America, have long been uncertain. Willeella mexicana has been generally accepted as a synonym of C. robusta, which is currently placed in the genus Struveopsis. Reinvestigation of type material and recently collected specimens from Mexico and Panama, including culture observations, along with a molecular phylogenetic analysis inferred from rDNA ITS1-5.8S-ITS2 sequences, confirm that both taxa belong to the same, morphologically variable species. Thallus architecture ranges from stipitate, Struveopsis-like blades (produced by apical cell divisions and formation of opposite and flabellate branches) to Valoniopsis-like …

Dietary Intakes Of Swedish Children And Adolescents: The European Heart Study, Emma Patterson

Masters

What children eat is important both for their health now and for their risk of chronic non communicable diseases, such as cardiovascular disease, in the future. The diets of 1,121 children (aged 9 y, n=552) and adolescents (aged 15 y, n=569) were assessed by an interviewer mediated 24-hour recall, as part of the European Youth Heart Study. Group macronutrient intakes and their food sources were described, and dietary energy density (ED) and breakfast habits were employed as markers of dietary quality. The effect of socioeconomic status on these markers was investigated. The adequacy of energy-reporting in this population was also …

Blunted Cystine–Glutamate Antiporter Function In The Nucleus Accumbens Promotes Cocaine-Induced Drug Seeking, Kristen S. Kau, Aric Madayag, John R. Mantsch, Mark D. Grier, Omer Abdulhameed, David A. Baker

Biomedical Sciences Faculty Research and Publications

Repeated cocaine alters glutamate neurotransmission, in part, by reducing cystine–glutamate exchange via system x_c−, which maintains glutamate levels and receptor stimulation in the extrasynaptic compartment. In the present study, we undertook two approaches to determine the significance of plasticity involving system x_c−. First, we examined whether the cysteine prodrug N-acetylcysteine attenuates cocaine-primed reinstatement by targeting system x_c−. Rats were trained to self-administer cocaine (1 mg/kg/200 μl, i.v.) under extended access conditions (6 h/day). After extinction training, cocaine (10 mg/kg, i.p.) primed reinstatement was assessed in rats pretreated with N-acetylcysteine (0–60 mg/kg, i.p.) in the …

Nectar Secondary Compounds Affect Self-Pollen Transfer: Implications For Female And Male Reproduction, Rebecca E. Irwin, Lynn S. Adler

Dartmouth Scholarship

Pollen movement within and among plants affects inbreeding, plant fitness, and the spatial scale of genetic differentiation. Although a number of studies have assessed how plant and floral traits influence pollen movement via changes in pollinator behavior, few have explored how nectar chemical composition affects pollen transfer. As many as 55% of plants produce secondary compounds in their nectar, which is surprising given that nectar is typically thought to attract pollinators. We tested the hypothesis that nectar with secondary compounds may benefit plants by encouraging pollinators to leave plants after visiting only a few flowers, thus reducing self-pollen transfer. We …

Knowledge-Based Analysis Of Genomic Expression Data By Using Different Machine Learning Algorithms For The Purpose Of Diagnostic, Prognostic Or Therapeutic Application, Venkata Jagan Mohan Thodima

Dissertations

With more and more biological information generated, the most pressing task of bioinformatics has become to analyze and interpret various types of data, including nucleotide and amino acid sequences, protein structures, gene expression profiling and so on. In this dissertation, we apply the data mining techniques of feature generation, feature selection, and feature integration with learning algorithms to tackle the problems of disease phenotype classification, clinical outcome and patient survival prediction from gene expression profiles.

We analyzed the effect of batch noise in microarray data on the performance of classification. Batchmatch, a batch adjusting algorithm based on double scaling method …

Vibration Causes Acute Vascular Injury In A Two-Step Process: Vasoconstriction And Vacuole Disruption, Sandya R. Govindaraju, James L. W. Bain, Thomas J. Eddinger, Danny A. Riley

Biological Sciences Faculty Research and Publications

Hand–arm vibration syndrome is a vasospastic and neurodegenerative occupational disease. In the current study, the mechanism of vibration- induced vascular smooth muscle cell (SMC) injury was examined in a rat-tail vibration model. Tails of male Sprague Dawley rats were vibrated continuously for 4 hr at 60 Hz, 49 m/s2 with or without general anesthesia. Ventral tail arteries were aldehyde fixed and embedded in epoxy resin to enable morphological analysis. Vibration without anesthesia caused vasoconstriction and vacuoles in the SMC. Anesthetizing rats during vibration prevented vasoconstriction and vacuole formation. Exposing tail arteries in situ to 1 mM norepinephrine (NE) for 15 …

Cellular And Synaptic Actions Of Acetylcholine In The Lamprey Spinal Cord, Katharina A. Quinlan, James T. Buchanan

Biological Sciences Faculty Research and Publications

This study investigated cellular and synaptic mechanisms of cholinergic neuromodulation in the in vitro lamprey spinal cord. Most spinal neurons tested responded to local application of acetylcholine (ACh) with depolarization and decreased input resistance. The depolarization persisted in the presence of either tetrodotoxin or muscarinic antagonist scopolamine and was abolished with nicotinic antagonist mecamylamine, indicating a direct depolarization through nicotinic ACh receptors. Local application of muscarinic ACh agonists modulated synaptic strength in the spinal cord by decreasing the amplitude of unitary excitatory and inhibitory postsynaptic potentials. The postsynaptic response to direct application of glutamate was unchanged by muscarinic agonists, suggesting …

Systematics And Floral Evolution In The Plant Genus Garcinia (Clusiaceae), Patrick Wayne Sweeney

Dissertations

The pantropical genus Garcinia (Clusiaceae), a group comprised of more than 250 species of dioecious, trees and shrubs, is a common component of lowland tropical forests and is best known by the highly prized fruit of mangosteen (G. mangostana). The genus exhibits as extreme diversity of floral form as is found anywhere in angiosperms and there are many unresolved taxonomic issues surrounding the genus. To understand patterns of floral evolution within the group and to evaluate morphology-based classification schemes involving Garcinia and its relatives, relationships among a broad sample of Garcinia and close relatives were inferred by conducting Bayesian, parsimony, …

Community Ecology And Phylogeography Of Bird Assemblages In Arid Zones Of Northern Venezuela: Implications For The Conservation Of Restricted-Range Birds, Adriana Rodriguez-Ferraro

Dissertations

Aridlands of northern Venezuela are important from an ornithological perspective because of the occurrence of habitat specialist birds that depend exclusively on desert scrubs and are endemic to this region. Currently, long-term survival of habitat specialists is threatened by ongoing changes in vegetation but the effects of such changes on bird assemblages are unknown. The goal of this study was to characterize bird assemblages found in six arid zones in northern Venezuela at both ecological and genetic levels, and to generate information relevant for conservation planning. The study involved assessments of patterns of avian species richness, abundance, community composition and …

Chloroplast Fe(Iii) Chelate Reductase Activity Is Essential For Seedling Viability Under Iron Limiting Conditions, Jeeyon Jeong, Christopher Cohu, Loubna Kerkeb, Marinus Pilon, Erin L. Connolly, Mary Lou Guerinot

Dartmouth Scholarship

Photosynthesis, heme biosynthesis, and Fe-S cluster assembly all take place in the chloroplast, and all require iron. Reduction of iron via a membrane-bound Fe(III) chelate reductase is required before iron transport across membranes in a variety of systems, but to date there has been no definitive genetic proof that chloroplasts have such a reduction system. Here we report that one of the eight members of the Arabidopsis ferric reductase oxidase (FRO) family, FRO7, localizes to the chloroplast. Chloroplasts prepared from fro7 loss-of-function mutants have 75% less Fe(III) chelate reductase activity and contain 33% less iron per microgram of chlorophyll than …

Lositan: A Workbench To Detect Molecular Adaptation Based On A Fst-Outlier Method, Tiago Antao, Ana Lopes, Ricardo J. Lopes, Albano Beja-Pereira, Gordon Luikart

Biological Sciences Faculty Publications

Background: Testing for selection is becoming one of the most important steps in the analysis of multilocus population genetics data sets. Existing applications are difficult to use, leaving many nontrivial, error-prone tasks to the user.

Results: Here we present LOSITAN, a selection detection workbench based on a well evaluated F_st-outlier detection method. LOSITAN greatly facilitates correct approximation of model parameters (e.g., genome-wide average, neutral F_st), provides data import and export functions, iterative contour smoothing and generation of graphics in a easy to use graphical user interface. LOSITAN is able to use modern multi-core processor architectures by …

Loading Mechanics In Femora Of Tiger Salamanders (Ambystoma Tigrinum) And Tegu Lizards (Tupinambis Merianae): Implications For The Evolution Of Limb Bone Design, Kathryn Wright

All Theses

The limb bones of tetrapods exhibit a wide range of shapes and sizes. Because locomotion is one of the most frequent and demanding behaviors in which limbs are used, this diversity in limb structure and design is frequently attributed to variation in the mechanical loading patterns that bones experience during locomotion. Limb bones are usually able to withstand loads much higher than they would normally experience before they fail. This margin of protection is known as a 'safety factor.' High safety factors would provide limb bones substantial insurance against failure, but could also make limb bones more costly to grow, …