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Effects Of Melatonin On Heartbeat And Possible Identification Of A Melatonin Receptor In Drosophila Melanogaster, Tricia L. Vankirk

Electronic Theses and Dissertations

Chapter 1 of this manuscript is a literature review that serves as an introduction to the entire dissertation. Chapter 2 examines the effects of the melatonin injection on heart rate and rhythmicity in Drosophila melanogaster Canton-S (wild-type) pupae and pupae bearing a variety of heart mutations. Chapter 3 investigates further the possible mechanisms of melatonin’s ability to increase heart rhythmicity without significantly affecting heart rate. A melatonin antagonist, luzindole; a high-affinity melatonin agonist, 2-iodomelatonin and RNAi techniques are used to identify a possible melatonin receptor in Drosophila melanogaster.

An appendix contains a previously published manuscript detailing experiments performed at the …

Atmospheric Nitrogen Assimilation In Ustilago Maydis., Michael Cooper

Electronic Theses and Dissertations

Nitrogen is an essential nutrient for all living creatures. Ammonium is one of the most efficiently used and thus preferred, sources of nitrogen. As with other dimorphic fungi, yeast-like cells of Ustilago maydis, a fungal pathogen of maize, switches to filamentous growth when starved for nitrogen/ammonium. U. maydis carries two genes, ump1 and ump2, encoding ammonium transporters that facilitate both uptake of ammonium and the filamentous response to its absence. While no obvious phenotype is observed when ump1 is deleted, cells without ump2 are unable to filament in response to low ammonium, although they can still grow. Surprisingly, …

Genomic And Transcriptomic Analyses Of Microbotryum Lychnidis-Dioicae Provide Insights Into The Biology Of A Fascinating Fungal Phytopathogen., Su San Toh

Electronic Theses and Dissertations

This study made use of the Silene latifolia/Microbotryum lychnidis-dioicae phytopathogen system as the focal system to establish the first reference genome for Microbotryum violaceum sensu lato. In silico analysis was performed on the genome assembly to identify various characteristics of the genome. Using RNA-Sequencing technologies on the Illumina platform, we collected transcriptomic data for both in vitro and in planta life stages of the fungus, providing the most comprehensive look at the gene expression and regulation of this fungus. Due to a lack of identifiable domains on the predicted genes, gene set enrichment analysis was done in …

Characterization Of Putative Exbb And Exbd Leads To The Identification Of A Potential Tol-Pal System In Rhizobium Leguminosarum Atcc 14479, Valeria Barisic

Electronic Theses and Dissertations

Rhizobium leguminosarum is a Gram negative nitrogen-fixing soil bacterium. Due to the limited bioavailability of iron, bacteria utilize siderophores that scavenge and bind available iron. The transport of iron-siderophore complexes is achieved by the TonB-ExbB-ExbD complex. We have previously shown that a functional TonB protein is necessary for iron transport by creating ΔtonB mutants and assessing their growth and 55Fe-siderophore transport ability. We attempted to identify and characterize the roles of putative exbB and exbD genes using a similar approach. Growth curves and sequence analyses suggest putative exbB and exbD may be the tolpal-associated genes tolQ and tolR. Phenotypic and …

Gene Expression In The Choanoderm, Jesús Federico Peña

Electronic Theses and Dissertations

The body plan of sponges (phylum Porifera) is an outlier among modern animals and is thought to have special evolutionary significance. Sponges lack muscles, nerves and a gut. Instead, they are composed of few cell types and simple tissues that function to pump water through an internal canal network where bacterial prey are filtered by a specialized tissue called the choanoderm. The choanoderm is composed of cells with striking similarity to choanoflagellates, the unicellular relatives of animals. Thus, the traditional view is that the sponge choanoderm is a useful model of the first animal epithelial tissues. Using the freshwater sponge …

The Role Of Artificial Structures In Facilitating Range Expansion Of The Introduced Barnacle Megabalanus Coccopoma In The Southeastern U.S.A., Alicia M. Reigel

Electronic Theses and Dissertations

The barnacle Megabalanus coccopoma is a recent invader of the southeastern U.S.A. from the tropical eastern Pacific. In Georgia, M. coccopoma populations along the immediate coastline often suffer extensive mortality during the winter, but population rebuilding is common after these events suggesting that there may be nearby larval sources. I investigated the hypothesis that artificial structures (i.e., buoys, towers), occurring far enough offshore of Georgia for water temperatures to be moderated by the Gulf Stream, provide refuges for breeding adults of M. coccopoma and can serve as the larval source. I investigated this hypothesis by first developing thirteen microsatellite primer …

Genetic Structure Of Ixodes Scapularis Say 1821 (Acari: Ixodidae), The Blacklegged Tick, By Microsatellite Analysis, John Ludwig

Electronic Theses and Dissertations

The blacklegged tick, Ixodes scapularis (Acari: Ixodidae) is the subject of intense research due to its economic importance from being a vector of several diseases. Previous studies have examined its taxonomic status and more recently, its genetic structure. This study embarked upon resolving the questions surrounding the genetic structuring of the tick, by using different molecular markers. Molecular data were first phylogenetically analyzed by using four different mitochondrial and nuclear markers (12SrDNA n=483, Dloop n=432, ITS2 n=156, Actin n=117). A Bayesian tree was inferred from the concatenated mitochondrial dataset, whereas nuclear gene markers were found to be uninformative. Nine microsatellites …

Helping To Resolve Taxonomic Conflicts Within The Genus Amblyomma (Acari:Ixodidae) From A Molecular Perspective, Paula Lado

Electronic Theses and Dissertations

This work sought to reassess the taxonomic status of Amblyomma parvum Aragao, 1908 and of the A. maculatum group of ticks Camicas, 1998. By using different molecular markers, 12SrDNA, 16SrDNA, DL, COI, COII (mitochondrial) and ITS2 (nuclear), I analyzed the systematic relationships between these taxa and their closest relatives. Phylogenetic analyses by maximum parsimony, maximum likelihood, and Bayesian analysis were performed in order to determine relationships among species and populations, and to determine the evolutionary history of these ixodids. The data obtained supported the hypothesis of cryptic speciation occurring within A. parvum, with the northern populations of Central America being …