Life Sciences Commons^™

Characterization Of Arabidopsis Eukaryotic Translation Initiation Factor 2Α (Eif2Α) Mutants, Mark Edens

Masters Theses

Plants are stationary organisms that are charged with overcoming a multitude of biotic and abiotic stresses. The eukaryotic translation initiation factor 2 (eIF2) is responsible for charging the P-site of the forming 80S ribosome with the initiator methionyl-tRNA. Thus, eIF2 is a protein of utmost consequence in the growth and development of organisms. The eIF2 protein is also a mediator of global translational regulation in the eukaryotic integrated stress response (ISR), where the α-subunit is phosphorylated by protein kinases, such as the kinase GCN2. Here, five eIF2α allele mutants in Arabidopsis were found to be deleterious to plant growth, development, …

Characterization Of Fusarium Species And Alternaria Alternata, And Their Effects On Switchgrass Health And Chemical Components, Sara Beth Collins

Masters Theses

Panicum virgatum L., readily referred to as Switchgrass, is a perennial warm-season bunch grass, used as an alternative energy source for biofuel production. There is insufficient research on switchgrass pathogens, and is expected that an increase in disease pressure will result as more land is reserved for this perennial crop. The purpose of this research was to identify and characterize pathogenic Alternaria alternata and Fusarium species on Switchgrass (Panicum virgatum L.), and to evaluate their impact on stand establishment and plant health. Molecular identifications of fungal isolates obtained from infected commercial switchgrass seed yielded eight species (A. alternata, …

Rapid Molecular Detection And Population Genetics Of Pityophthorus Juglandis, A Vector Of Thousand Cankers Disease In Juglans Spp., Emel Oren

Masters Theses

Thousand Cankers Disease (TCD) is a disease complex involving the fungal pathogen Geosmithia morbida, an insect vector Pityophthorus juglandis, and the hosts, Juglans spp. and Pterocarya spp. Signs and symptoms of TCD include crown thinning due to branch dieback, yellowing and wilting of the leaves, appearance of epicormic shoots, numerous entrance/exit holes, gallery formation by P. juglandis, and the development of small, dark brown cankers underneath the bark. TCD originally described from western U.S., has now expanded to eastern U.S. and northwestern Italy. The disease complex is often difficult to diagnose due to the absence of symptoms …

Environmental Controls On The Diversity And Distribution Of Endosymbionts Associated With Phacoides Pectinatus (Bivalvia: Lucinidae) From Shallow Mangrove And Seagrass Sediments, St. Lucie County, Florida, Thomas Walters Doty

Masters Theses

Lucinid bivalves are capable of colonizing traditionally inhospitable shallow marine sediments due to metabolic functions of bacterial endosymbionts located within their gills. Because lucinids can often be the dominant sediment infauna, defining their roles in sediment and pore fluid geochemical cycling is necessary to address concerns related to changes in coastal biological diversity and to understanding the sensitivity of threatened coastal ecosystems over time. However, there has been limited research done to understand the diversity and distribution of many lucinid chemosymbiotic systems. Therefore, the goals of this thesis were to evaluate the distribution of Phacoides pectinatus and its endosymbiont communities …

Manipulating Adipose Tissue Fatty Acid Oxidation To Reduce Fatness In Broiler Chickens, Tania Emmanuelle Torchon

Masters Theses

Compared to rodents, broiler chickens, those reared for meat, are an attractive model for studies of adipose biology, and obesity development in children. The broiler chicken lacks the gene for uncoupling protein 1, the hallmark for brown adipose tissue making them a useful model to study lipid metabolism in white adipocytes. Two studies were performed to investigate if white adipose tissue had the metabolic ability for fatty acid oxidation (FAO), and to investigate the effects of dietary fatty acids on abdominal fat development of young broiler chickens as a model for childhood obesity. In study one, chickens were fasted for …

A Step Towards Understanding Of The Molecular Basis Of Ligand Promiscuity In The Aminoglycoside Modifying Enzymes, Sherin R. Raval

Masters Theses

Aminoglycosides have proven very useful in the treatment of infections; lately their effectiveness has been greatly reduced due to increasing resistance. Among many known mechanisms of resistance to aminoglycosides, enzymatic modification is the most prevailing. More than 14 aminoglycoside -N3-acetyltransferases- a class of aminoglycoside modifying enzymes, are known today. This study focuses on a pair of acetyl transferases: The aminoglycoside-N3- acetyltransferase IIIb (AAC-IIIb) and the aminoglycoside-N3- acetyltransferase IIa (AAC-IIa). AAC-IIa and AAC-IIIb are very similar in their amino acid sequence and structure – yet they have a strong difference in their substrate selectivity, kinetic …

Localization Of Chemoreceptors In Azospirillum Brasilense., Anastasia Aksenova

Masters Theses

In order to ensure their survival, bacteria must sense and adapt to a variety of environmental signals. Motile bacteria are able to orient their movement in a chemical gradient by chemotaxis. During chemotaxis, environmental signals are detected by chemotaxis receptors and are propagated via a signal transduction cascade to affect bacterial motility. In a model organism Escherichia coli, chemotaxis receptors, also called MCPs (for methyl-accepting chemotaxis proteins) sense changes in concentration gradients by making temporal comparisons about the chemical composition of their surroundings. Decreased attractant concentration or increased repellant concentration results in conformational changes in the MCPs that culminate …

Demonstration Of A Targeted Proteome Characterization Approach For Examining Specific Metabolic Pathways In Complex Bacterial Systems, Adam Justin Martin

Masters Theses

Multiple Reaction Monitoring (MRM) is a powerful tandem mass spectrometry (MS/MS) tool frequently implemented in proteomic studies to provide targeted analysis of proteins and peptides. The selectivity that MRM delivers is so strong that it provides the quadrupole mass spectrometers (QQQ), on which it is commonly employed, with pertinence to proteomic studies that they would otherwise lack for their relatively low resolution. Additionally, this increased level of selectivity is sufficient enough to supplant complicated fractionation techniques, additional dimensions of chromatography, and 24 hour long MS/MS experiments in simplistic biological samples. But there is a deficiency of evidence to determine the …

Single-Nucleotide Polymorphisms Associated With Performance Traits In Beef Cattle Grazing Endophyte-Infected Tall Fescue, Bryan Christopher Bastin

Masters Theses

Tall fescue (Lolium arundinaceum Schreb.) is the most prevalent forage in the Midsouth United States due in part to the presence of the endophytic fungus Neotyphodium coenophialum. The fungus, while conferring hardiness to tall fescue, contributes to decreased production efficiency in cow-calf operations. A previous genome-wide association study was performed using the Illumina 50k bovine SNP chip. Twenty-four SNP were found to be associated (P < 0.05) with adjusted birth weight and adjusted 205-day weights of calves from 48 beef cows at Ames Plantation. The first objective was to validate each SNP by testing associations with several additional phenotypes. Custom Taqman genotyping assays (Applied Biosystems, Foster City, CA) were subsequently designed to genotype each SNP in beef cattle located at Tennessee Tech University (n = 654), to validate associations in a large, independent herd. The results yielded 15 associations that were significant (P < 0.05) with 6 phenotypes linked to those affected by fescue toxicosis. The second objective investigated the link between fescue toxicosis and the XK, Kell blood group complex subunit-related, member 4 …

Bioconfinement Of A Putatively Sterile Nicotiana Hybrid And Development Of Tools For Assessing Gene Flow, John Hollis Rice

Masters Theses

Production of transgenic crops in open field environments is an ongoing concern of due to the potential for gene flow. New transgenic crops, such as plant-made-pharmaceuticals may generate additional concerns about effects of adventitious transgenes. Use of a bioconfinement strategy may alleviate any consequences by preventing gene flow. The following chapters discuss previous and current research on gene flow, testing of a Nicotiana hybrid system for bioconfinement efficiency, and development of methods for transgene detection. The candidate ‘platform plant’ that was tested is a Nicotiana hybrid (Nicotiana tabacum ‘TN 90’ × Nicotiana glauca) previously identified to be sexually …

Characterization Of A Glycosyphosphatidylinositol Anchor Transamidase In Arabidopsis Thaliana And The Function Of Gpi Anchored Proteins In Stomatal Development, Mark Gerald Ronald Bundy

Masters Theses

In plants stomata play a vital role for survival by allowing the gas exchange of CO₂ [carbon dioxide] and water vapor to occur. A stoma is a central pore flanked by two kidney shaped guard cells and in wild type there is at least one pavement cell between each stoma. The ERECTA (ER) gene family consisting of ER, ERL1, ERL2 is involved in regulation of stomata development, where a triple mutant of er erl1 erl2 displays an increased stomata index and clusters of stomata that disobey the one cell spacing rule. To better understand the pathway of stomata development, …

Studies On Solo Working Mechanism In The Meiosis Of Drosophila Melanogaster, Qian Ma

Masters Theses

In eukaryotes, sister chromatids are closely aligned due to cohesion, a process essential for chromosome pairing and segregation during both mitosis and meiosis. A conserved cohesin complex in a ring structure is composed of four subunits, including each of these four members or their homologs, SMC1, SMC3, SCC1/RAD21/REC8, and SCC3/SA. Up to now, no REC8 homolog has been identified in the meiosis of Drosophila. SOLO is a meiotic protein required for accurate chromosome segregation, centromere cohesion, and cohesin complex localization in Drosophila meiosis. In addition, SOLO is required for synapsis and recombination in Drosophila female meiosis.

In this study, …

Angiotensinogen Gene Silencing Reduces Lipid Accumulation And Inflammation In Cultured 3t3-L1 Adipocytes, Wenting Xin Carroll

Masters Theses

Obesity is characterized by metabolic complications which are related to several life-threatening diseases. Dysregulated inflammatory adipokines secretion from adipose tissue is believed as the major contributor to obesity-associated local and systemic inflammation, insulin resistance, and other metabolic dysfunctions.

Numerous studies in our lab and others pointed to the role of local adipose tissue renin-angiotensin system (RAS) in the pathogenesis of obesity, inflammation and insulin resistance. We hypothesized that adipocytes-derived angiotensinogen (Agt) played a critical role in adipogenesis and/or lipogenesis as well as adipose inflammation. To test, we established 3T3-L1 preadipocytes stably transfected with Agt-shRNA or scrambled sequence (Sc-shRNA). Transfected preadipocytes …

Designing Protein Expression And Purification Systems For Recombinant Z Alpha1-Antitrypsin Using The Methylotrophic Yeast, Pichia Pastoris, Monique Jenaie Lemieux

Masters Theses

It is well established that improper protein folding often leads to the formation of aggregates whose consequences are cellular impairment and cell death. One example of this is the aggregation of the mutant Z Alpha1-Antitrypsin protein, which results in blocking of its secretion due to inclusion body formation. This can contribute not only to the development of chronic obstructive pulmonary disease but also to hepatitis, cirrhosis and hepatocellular carcinoma. Current treatments are principally limited to intravenous Alpha1-Antitrypsin therapy and organ transplantation. In the scientific community though, it is widely thought that more effective forms of treatments lie within the polymerization …

Genetic Basis Of Flocculation In Azospirillum Brasilense., Priyanka Satish Mishra

Masters Theses

Azospirillum brasilense is a class of rhizobacteria capable of nitrogen fixation, root colonization and hence promoting host plant growth. The bacteria posses cell interaction behaviors like clumping and flocculation that contribute the survival of the organism in nutrient limited conditions. Change in the cell surface adhesive properties allows the cells to progress from free swimming to clumping and finally flocculation. Less is known about the genetic regulation of these processes with flcA being the only transcriptional regulator known so far to directly control flocculation. Recent evidence suggesting that Che1, a chemotaxis like signal transduction pathway controls the cell behavior clumping …

Elucidating The Effect Of Silver On Ethylene Signaling In Arabidopsis Thaliana, Brittany Kathleen Mcdaniel

Masters Theses

Ethylene, a gaseous plant hormone, is involved in numerous plant developmental processes such as seed germination, senescence, and fruit ripening. In Arabidopsis thaliana, ethylene is perceived by a family of five membrane-bound receptors, which upon binding ethylene trigger downstream effects. At the receptor level, it is known that the coordination of a copper ion is necessary for ethylene to bind, resulting in a conformational change of the receptor and the initiation of the ethylene signal transduction pathway. Interestingly, silver ions are also able to support binding of ethylene but ethylene responses are blocked in the presence of silver. When …

Examining The Roles Of Pstoc75 Potra Domains In Chloroplast Protein Import, Richard Franklin Simmerman

Masters Theses

During chloroplast formation via endosymbiosis most of the plastid genome was transferred to the host nuclear genome. Genomic and proteomic analysis suggests that >95% of the original plastid proteome is now encoded in the nucleus, and these now cytosolically fabricated proteins require a post-translational transport pathway back into the organelle. This process is not well understood, yet it has been shown to involve translocons at the outer and inner envelope of the chloroplast membranes (TOC & TIC). These translocons interact with a cleavable N-terminal extension of between 20 and 100 residues on chloroplast-bound precursor proteins known as the transit-peptide. Precursor …

The Effects Of Bisphenol A On Adipose Tissue Development, Metabolism, And Endocrine Function And The Role It May Play In The Development Of Obesity, Brantley Nelson Wyatt

Masters Theses

While diet and sedentary lifestyle remain important factors in the development of obesity, recent findings have shown the possible involvement of environmental obesogens, chemicals that can disrupt homeostatic energy balance and increase adiposity. Bisphenol A (BPA) is a compound used in the manufacturing of plastics as a hardening agent and is ubiquitous in the environment due to its widespread use. BPA has been shown to be an endocrine disruptor through its ability to mimic estrogen, which is now known to play important roles in adipose tissue growth and metabolism. In fact, a small but compelling number of studies have shown …

Structural And Functional Analysis Of Toc75, Ashita Mukul Dave

Masters Theses

The majority of chloroplast proteins are nuclear-encoded and post-translationally imported into the chloroplast. These newly imported proteins are translocated from the cytosolic compartment to the stroma by the Translocons of the Outer/Inner membranes of Chloroplast (TOC/TIC). In order to understand protein transport across the chloroplast outer membrane, it is crucial to investigate the structure and function of these complexes. The TOC complex is composed of the beta-barrel channel protein Toc75 and the GTPase receptors Toc34 and Toc159.

Toc75 is a member of the OMP85 (Outer Member Protein, 85 kDa) superfamily. Other proteins of the OMP85 superfamily also exist in Gram-negative …

Study Of The Structure And Function Of Cxc Chemokine Receptor 2, Hae Ryong Kwon

Masters Theses

It has been shown that the amino terminus and second extracellular loop (EC2) of CXCR2 are crucial for ligand binding and receptor activation. The lack of an ionic lock motif in the third intracellular loop of CXCR2 focuses an investigation of the mechanism by which these two extracellular regions contribute to receptor recognition and activation.

The first objective of this investigation was to predict the structure of CXCR2 based on known structures of crystallized GPCRs. Rhodopsin, β2-adrenergic receptor, CXCR4 were used for homology modeling of CXCR2 structure. Highly conserved motifs found in sequence alignments of the template GPCRs were helpful …

Four Aspects Of Dogwood Pollination: Insect Visitation, A Novel Approach To Identify Pollen, Floral Volatile Emission, And Tracking Parentage, Paul Raymond Rhoades

Masters Theses

Part 1: Visitation of potential pollinators to Cornus florida and C. kousa flowers was assessed in East Tennessee in 2008 and 2009. Data regarding insect visitation rates to multiple trees per location were gathered throughout the flowering period. Diurnal and seasonal variations in visitation were recorded. Pollen coverage was assessed on portions of captured insect exoskeletons that were most likely to contact the stigma. Eleven families in four insect orders were collected from C. florida and 26 families in five orders from C. kousa. The most important pollinators in eastern Tennessee were bees in the Andrenidae and Halictidae. The most …

Linkage Analysis Of Caffeine Resistance And Circadian Rhythm In Caffeine-Treated Ddt Resistant And Susceptible Strains Of Drosophila Melanogaster, Chandrashis Bhowmick

Masters Theses

Caffeine is found in coffee, tea, soft drinks, many plant products and various drug preparations. It is the most consumed common psychoactive drug around the world. Consumption of caffeine causes several behavioral and physiological responses in humans and other mammals. Caffeine is also known to be an insect repellant and can be used as an insecticide. As observed in mammals, caffeine treatment increases the locomotor activity in insects including Drosophila. However, very little is known about genetic and molecular basis of caffeine sensitivity and action in insects. In the present study, I have used DDT resistant (91-R) and susceptible …

Studies On The Mechanisms Of Homolog Pairing And Sister Chromatid Cohesion During Drosophila Male Meiosis, Jian Ma

Masters Theses

Meiosis is a complex process involving one round of DNA replication followed by two rounds of cell divisions. The proper segregation of homologs at meiosis I and sister chromatids during meiosis II is essential for the survival of the offspring. Aberrant chromosome segregation at any stage of meiosis can lead to aneuploidy. Meiotic chromosome segregation without crossing over or chiasmata is a widespread but poorly understand chromosome segregation pathway. In male Drosophila meiosis the absence of recombination in chromosomes makes it easier to identify mutations which influence homologous chromosome pairing and segregation.

Modifier of Mdg4 in Meiosis (MNM), a protein …

The Effects Of Acute Ethanol Treatment On The Suprachiasmatic Nucleus In Adult Male Mice, Charles Andrew Mangrum

Masters Theses

Light is the primary entraining signal for the mammalian circadian clock located in the suprachiasmatic nucleus (SCN). Light entering the eye leads to release of glutamate directly onto SCN neurons where it binds to N-methyl D-aspartate (NMDA) receptors initiating a cascade of cellular processes that ultimately modulates clock phase. SCN neurons show a 24-hour rhythm in neuronal activity that peaks in the middle of the day when isolated in a brain slice preparation. Treatments that phase-shift the SCN clock in vivo have been shown similarly to shift this rhythm of neuronal activity in vitro. Here, I have investigated …