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Articles 1 - 18 of 18
Full-Text Articles in Life Sciences
Katp Channel Phosphorylation: Mechanisms And Contribution To Vascular Tone Regulation By Vasodilating And Vasoconstricting Hormones And Neurotransmitters, Yun Shi
Biology Dissertations
Contractility of vascular smooth muscles (VSMs) in resistance arteries determines systemic blood pressure and blood supplies to local tissues, in which ATP sensitive K+ (KATP) channels play a role. The KATP channels that couple metabolic state to cellular activity are activated by multiple hormonal vasodilators and inhibited by vasoconstrictors. To understand the molecular mechanisms for the channel regulation by vasodilators, we studied the effects of β-adrenergic receptors on Kir6.1/SUR2B in HEK cells. Stimulation of β-adrenergic receptors activated the channels, which relied on the GS-protein, adenylyl cyclase, cAMP and PKA system. Using mutational analysis, we scanned all the putative PKA sites …
Sexual Plasticity In A Marine Goby (Lythrypnus Dalli): Social, Endocrine, And Genetic Influences On Functional Sex, Edmund William Rodgers
Sexual Plasticity In A Marine Goby (Lythrypnus Dalli): Social, Endocrine, And Genetic Influences On Functional Sex, Edmund William Rodgers
Biology Dissertations
Sex determination occurs early in development for most animals, at which time sex is fixed for life. Many teleost fishes, however, exhibit remarkable sexual plasticity throughout their life history, ranging from multiple morphs within a sex to functional adult sex reversal. To understand the development and evolution of adult sex reversal, I examined behavioral, endocrine, and genetic contributions to the regulation of functional sex in adult animals, using the bluebanded goby (Lythrypnus dalli) as an experimental model. This species was found to be equally capable of sexual transitions from female to male (protogyny) as from male to female (protandry). Throughout …
Functional Analyses Of West Nile Virus (Wnv) Bicistronic Replicons Containing Different Sequence Elements And Of Simian Hemorrhagic Fever Virus (Shfv) Polyprotein Processing, Gertrud Ulrike Radu
Functional Analyses Of West Nile Virus (Wnv) Bicistronic Replicons Containing Different Sequence Elements And Of Simian Hemorrhagic Fever Virus (Shfv) Polyprotein Processing, Gertrud Ulrike Radu
Biology Dissertations
The flavivirus West Nile virus (WNV) encodes a single polyprotein that is processed into three structural and seven nonstructural proteins. Various WNV bicistronic replicons that direct cap-dependent translation of an N-terminal viral capsid or capsid/Renilla luciferase fusion protein as well as IRES-dependent translation of the nonstructural proteins were constructed. An original replicon consisting of the WNV 5' NCR, the 5' 198 nts of the capsid coding sequence, which included the 5' cyclization sequence (Cyc), and an EMCV IRES followed by the WNV nonstructural genes and 3' NCR was generated. Real time qRT-PCR analysis of intracellular levels of this replicon RNA …
Neuropeptide Y-Mediated Control Of Appetitive And Consummatory Ingestive Behaviors In Siberian Hamsters (Phodopus Sungorus), Megan J. Dailey
Neuropeptide Y-Mediated Control Of Appetitive And Consummatory Ingestive Behaviors In Siberian Hamsters (Phodopus Sungorus), Megan J. Dailey
Biology Dissertations
During the past few decades, obesity has risen significantly in the United States with recent estimates showing that 65% of Americans are overweight and 30% are obese. This increase is a major cause for concern because obesity is linked to many secondary health consequences that include type II diabetes, heart disease, and cancer. Current approaches to the obesity problem primarily have focused on controls of food intake and have been largely unsuccessful. Food, however, almost always has to be acquired (foraging) and frequently is stored for later consumption (hoarding). Therefore, a more comprehensive approach that includes studying the underlying mechanisms …
Serotonergic Modulation Of The Crayfish Hindgut: Effects On Hindgut Contractility And Regulation Of Serotonin On Hindgut, Barbara Ellen Musolf
Serotonergic Modulation Of The Crayfish Hindgut: Effects On Hindgut Contractility And Regulation Of Serotonin On Hindgut, Barbara Ellen Musolf
Biology Dissertations
Serotonin (5-hydroxytryptamine, 5-HT) has long been associated with the vertebrate gut and is an important neuromodulator of crustacean foregut. This dissertation presents evidence that 5-HT initiated peristalsis in crayfish hindgut and enhanced the power of contractions in caudal regions of the hindgut. 5-HT receptor immunoreactivity studies showed that the two identified crustacean 5-HT receptors, 5-HT1α and 5-HT2β are present on the hindgut in different and distinctive patterns. 5-HT immunoreactivity (5-HT-ir) studies revealed that the fibers from central neurons found on the hindgut showed a broad range of 5-HT-ir intensity, which led to the hypothesis that they borrowed 5-HT. …
Functional Characterization Of The Arginine Transaminase Pathway In Pseudomonas Aeruginosa Pao1, Zhe Yang
Functional Characterization Of The Arginine Transaminase Pathway In Pseudomonas Aeruginosa Pao1, Zhe Yang
Biology Dissertations
Arginine utilization in Pseudomonas aeruginosa with multiple catabolic pathways represents one of the best examples of metabolic versatility of this organism. To identify genes of this complex arginine network, we employed DNA microarray to analyze the transcriptional profiles of this organism in response to L-arginine. While most genes in arginine uptake, regulation and metabolism have been identified as members of the ArgR regulon in our previous study, eighteen putative transcriptional units of 38 genes including the two known genes of the arginine dehydrogenase (ADH) pathway, kauB and gbuA, were found inducible by exogenous L-arginine but independent of ArgR. The potential …
Neuronal Growth Cone Dynamics Are Regulated By A Nitric Oxide-Initiated Second Messenger Pathway., Kristy Welshhans
Neuronal Growth Cone Dynamics Are Regulated By A Nitric Oxide-Initiated Second Messenger Pathway., Kristy Welshhans
Biology Dissertations
During development, neurons must find their way to and make connections with their appropriate targets. Growth cones are dynamic, motile structures that are integral to the establishment of appropriate connectivity during this wiring process. As growth cones migrate through their environment, they encounter guidance cues that direct their migration to their appropriate synaptic targets. The gaseous messenger nitric oxide (NO), which diffuses across the plasma membrane to act on intracellular targets, is a signaling molecule that affects growth cone motility. However, most studies have examined the effects of NO on growth cone morphology when applied in large concentrations and to …
B Virus Uses A Different Mechanism To Counteract The Pkr Response, Li Zhu
B Virus Uses A Different Mechanism To Counteract The Pkr Response, Li Zhu
Biology Dissertations
B virus (Cercopithecine herpesvirus 1), which causes an often fatal zoonotic infection in humans, shares extensive homology with human herpes simplex virus type 1 (HSV-1). The ƒ×134.5 gene of HSV-1 plays a major role in counteracting dsRNA-dependent protein kinase (PKR) activity. HSV-1 Us11 protein, if expressed early as a result of mutation, binds to PKR and prevents PKR activation. The results of experiments in this dissertation revealed that although B virus lacks a ƒ×134.5 gene homolog, it is able to inhibit PKR activation, and subsequently, eIF2ƒÑ phosphorylation. The initial hypothesis was that B virus Us11 protein substitutes for the function …
Kir Channels In Co2 Central Chemoreception: Analysis With A Functional Genomics Approach, Asheebo Rojas
Kir Channels In Co2 Central Chemoreception: Analysis With A Functional Genomics Approach, Asheebo Rojas
Biology Dissertations
The process of respiration is a pattern of spontaneity and automatic motor control that originate in the brainstem. The mechanism by which the brainstem detects CO2 is termed central CO2 chemoreception (CCR). Since the early 1960’s there have been tremendous efforts placed on identification of central CO2 chemoreceptors (molecules that detect CO2). Even with these efforts, what a central CO2 chemoreceptor looks like remain unknown. To test the hypothesis that inward rectifier K+ (Kir) channels are CO2 sensing molecules in CCR, a series of experiments were carried out. 1) The first question asked was whether the Kir4.1-Kir5.1 channel is expressed …
Structural, Kinetic And Mutational Analysis Of Two Bacterial Carboxylesterases, Ping Liu
Structural, Kinetic And Mutational Analysis Of Two Bacterial Carboxylesterases, Ping Liu
Biology Dissertations
The crystal structures of two thermostable carboxylesterase Est30 and Est55 from Geobacillus stearothermophilus were determined to help understand their functions and applications in industry or medicine. The crystal structure of Est30 was determined at 1.63 Å resolution by the multiple anomalous dispersion method. The two-domain Est30 structure showed a large domain with a modified alpha/beta hydrolase core including a seven, rather than an eight-stranded beta sheet, and a smaller cap domain comprising three alpha helices. A 100 Da tetrahedral ligand, propyl acetate, was observed to be covalently bound to the side chain of Ser94 in the catalytic triad. This ligand …
Studies Directed To The Optimization Of Fermentation Of Rhodococcus Sp. Dap 96253 And Rhodococcus Rhodochrous Dap 96622, Gene K. Drago
Studies Directed To The Optimization Of Fermentation Of Rhodococcus Sp. Dap 96253 And Rhodococcus Rhodochrous Dap 96622, Gene K. Drago
Biology Dissertations
Studies Directed to the Optimization of Fermentation of Rhodococcus sp. DAP 96253 and Rhodococcus rhodochrous DAP 96622 by GENE KIRK DRAGO Under the Direction of George E. Pierce ABSTRACT Bench- and pilot plant scale fed-batch fermentations were performed in stirred-tank bioreactors (STBR) with Rhodococcus sp. DAP 96253 and R. rhodochrous DAP 96622 in an attempt to elucidate parameters that may affect the optimization of a fermentation process for high biomass production and high inducible expression of cobalt-high-molecular-mass nitrile hydratase (Co-H-NHase. The effects of these factors on amidase (AMDase) activity were also investigated. Biomass and NHase production were inhibited by a …
Protein Binding Sites And Cis-Acting Sequences On The West Nile Virus 3' (+) Sl Rna, William G. Davis
Protein Binding Sites And Cis-Acting Sequences On The West Nile Virus 3' (+) Sl Rna, William G. Davis
Biology Dissertations
RNase footprinting and nitrocellulose filter-binding assays were previously used to map one major and two minor binding sites for the cell protein eEF1A on the 3’(+) stem loop (SL) RNA of West Nile virus (WNV) (2). Base substitutions in the major eEF1A binding site or adjacent areas of the 3’(+) SL were engineered into a WNV infectious clone. Mutations that decreased, as well as ones that increased, eEF1A binding in in vitro assays had a negative affect on viral growth. None of these mutations affected the efficiency of translation of the viral polyprotein from the genomic RNA, but all of …
Mechanisms For Cadmium Lumen-To-Cell Transport By The Luminal Membrane Of The Rabbit Proximal Tubule, Yanhua Wang
Mechanisms For Cadmium Lumen-To-Cell Transport By The Luminal Membrane Of The Rabbit Proximal Tubule, Yanhua Wang
Biology Dissertations
The lumen-to-cell transport, cellular accumulation, and toxicity of ionic cadmium (109Cd2+) and cadmium-cysteine conjugate (Cys-S-109Cd-S-Cys) were studied in isolated perfused S2 segments of the proximal tubule of the rabbit kidney. All perfusion solutions were HEPES buffered and contained 3H-L-glucose which functioned as a volume and leak marker along with 250 nM FD & C Green dye as a vital dye. When ionic cadmium, 0.73µM Cd2+, or 0.73µM cadmium-cysteine conjugate (Cys-S-109Cd-S-Cys) containing solution was perfused through the lumen of the tubule there was no visual evidence of toxicity such as blebbing of the luminal membrane, cellular vital dye uptake, and cellular …
Functional Roles Of Crustacean Dual Antennular Chemosensory Pathways In Odor Mediated Behaviors, Amy Jean Horner
Functional Roles Of Crustacean Dual Antennular Chemosensory Pathways In Odor Mediated Behaviors, Amy Jean Horner
Biology Dissertations
Odor signals mediate a variety of behaviors in animals across a diversity of taxa. Despite dramatic morphological differences between animals from different taxa, several important features of olfactory system organization and processing are similar across animals. Because of this similarity, a number of different organisms including mammals, insects, and decapod crustaceans serve as valuable model systems for understanding general principles of olfactory processing. As in other organisms, including both vertebrates and insects, the chemosensory system of decapod crustaceans is organized into multiple anatomically distinct neuronal pathways. The two main pathways (the aesthetasc/ olfactory lobe pathway and non-aesthetasc/ lateral antennular neuropil …
Kinetic And Crystallographic Studies Of Drug-Resistant Mutants Of Hiv-1 Protease: Insights Into The Drug Resistance Mechanisms, Fengling Liu
Kinetic And Crystallographic Studies Of Drug-Resistant Mutants Of Hiv-1 Protease: Insights Into The Drug Resistance Mechanisms, Fengling Liu
Biology Dissertations
HIV-1 protease (PR) inhibitors (PIs) are important anti-HIV drugs for the treatment of AIDS and have shown great success in reducing mortality and prolonging the life of HIV-infected individuals. However, the rapid development of drug resistance is one of the major factors causing the reduced effectiveness of PIs. Consequently, various drug resistant mutants of HIV-1 PR have been extensively studied to gain insight into the mechanisms of drug resistance. In this study, the crystal structures, dimer stabilities, and kinetics data have been analyzed for wild type PR and over 10 resistant mutants including PRL24I, PRI32V, PRM46L, PRG48V, PRI50V, PRF53L, PRI54V, …
Analysis Of The Cellular Proteins, Tia-1 And Tiar, And Their Interaction With The West Nile Virus (Wnv) 3' Sl Minus-Strand Rna, Mohamed Maged Emara
Analysis Of The Cellular Proteins, Tia-1 And Tiar, And Their Interaction With The West Nile Virus (Wnv) 3' Sl Minus-Strand Rna, Mohamed Maged Emara
Biology Dissertations
The 3' terminal stem loop of the WNV minus-strand [WNV3'(-) SL] RNA was previously shown to bind the cell protein, T-cell intracellular antigen-1 (TIA-1), and the related protein, TIAR. These two proteins are known to bind AU-rich sequences in the 3' UTRs of some cellular mRNAs. AU stretches are located in three single-stranded loops (L1, L2, and L3) of the WNV3'(-) SL RNA. The RNA binding activity of both proteins was reduced when L1 or L2, but not L3, AU sequences were deleted or substituted with Cs. Deletion or substitution with Cs of the entire AU-rich sequence in either L1 …
Mechanistic Insight Into Subunit Stoichiometry For Kir Channel Gating: Ligand Binding, Gating, Binding-Gating Coupling, Coordination, And Cooperativity, Runping Wang
Biology Dissertations
Ligand-gated ion channels couple intra- and extracellular chemical signals to cellular excitability. In response to a specific ligand, these channels change their permeability to certain ions by opening or closing their ion conductive pathway, a controlling mechanism known as channel gating. Although recent studies with X-ray crystallography and site-directed mutagenesis have revealed several structures potentially important for channel gating, the gating mechanism is still elusive. Ligand-dependent channel gating involves a series of transient events and asymmetric movements of individual subunits. Understanding of these events appears to be a challenge to current approaches in gating studies by using the homomeric wild-type …
Enhanced Stabilization Of Nitrile Hydratase Enzyme From Rhodococcus Sp. Dap 96253 And Rhodococcus, Sangeeta Ganguly
Enhanced Stabilization Of Nitrile Hydratase Enzyme From Rhodococcus Sp. Dap 96253 And Rhodococcus, Sangeeta Ganguly
Biology Dissertations
Treatment of industrial wastewaters contaminated with toxic and hazardous organics can be a costly process. In the case of acrylonitrile production, due to highly volatile and toxic nature of the contaminant organics, production wastewaters are currently disposed by deepwell injection without treatment. Under the terms granting deepwell injection of the waste, alternative treatments must be investigated, and an effective treatment identified. Cells of two Gram-positive bacteria, Rhodococcus sp. DAP 96253 and R. rhodochrous DAP 96622 were evaluated for their potential as biocatalysts for detoxification of acrylonitrile production wastewaters. Rhodococcus sp. DAP 96253 and R. rhodochrous DAP 96622 when multiply induced, …