Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 12 of 12
Full-Text Articles in Entire DC Network
Genetic And Biochemical Properties Of Arabidopsis Rna Polymerases Iv And V, Jeremy Haag
Genetic And Biochemical Properties Of Arabidopsis Rna Polymerases Iv And V, Jeremy Haag
All Theses and Dissertations (ETDs)
RNA Polymerases IV and V: Pol IV and Pol V) are plant-specific enzyme complexes with subunit homology to RNA Polymerase II: Pol II). The largest subunits in Pol IV and Pol V, NRPD1 and NRPE1 respectively, share a second largest subunit, NRPD2/NRPE2. The evolutionarily conserved Metal A and Metal B binding sites are required for Pol IV and V in vivo function fitting the prediction that these are functional polymerases. The Defective Chloroplast and Leaves-like: DeCL) domain at the C-terminus of both NRPD1 and NRPE1 is also required for complementation but other domains in the NRPE1 CTD are largely dispensable. …
Evolution Of Endosperm Starch Synthesis Pathway Genes In The Context Of Rice: Oryza Sativa) Domestication, Guoqin Yu
All Theses and Dissertations (ETDs)
The evolution of metabolic pathways is a fundamental but poorly understood aspect of evolutionary change. The rice endosperm starch biosynthetic pathway is one of the most thoroughly characterized biosynthesis pathways in plants, and starch is a trait that has evolved in response to strong selection during rice domestication and subsequent crop improvement. In this study, I have examined six key genes in the rice endosperm starch biosynthesis pathway to investigate the evolution of this pathway before rice domestication and during rice domestication. Oryza rufipogon is the wild ancestor of cultivated rice: Oryza sativa). Oryza sativa has five variety groups: aus, …
A Role For The Ecdysone Response Gene E93 In Imaginaling Patterning During Metamorphosis, Xiaochun Mou
A Role For The Ecdysone Response Gene E93 In Imaginaling Patterning During Metamorphosis, Xiaochun Mou
All Theses and Dissertations (ETDs)
Drosophila melanogaster E93 is an early ecdysone response gene that encodes a pipsqueak domain transcription factor. E93 is induced by ecdysone at the end of larval development, and directs the death and elimination of several larval tissues during metamorphosis. Although E93 has been considered a dedicated regulator of larval cell death, I have found that E93 is also widely expressed in imaginal tissues during metamorphosis, where it is required for the proper patterning of many adult structures. Our working hypothesis is that E93 functions in imaginal tissues as a metamorphosis-specific cofactor that determines the pupa-specific action of numerous other transcription …
Flap Endonuclease 1 Ensures Telomere Replication And Stability, Abhishek Saharia
Flap Endonuclease 1 Ensures Telomere Replication And Stability, Abhishek Saharia
All Theses and Dissertations (ETDs)
Telomeres, protein-DNA structures that distinguish the end of a chromosome from a bona fide DNA double strand break, are integral to genomic stability. High fidelity replication of telomeres is indispensable for their stability. Telomere replication is a challenging task that is completed through the coordinated actions of telomere binding proteins and DNA replication and repair proteins in ways that are not well understood. This work focuses on delineating the function of one DNA replication and repair protein, Flap Endonulcease 1: FEN1), in telomere replication and maintenance. I demonstrate that FEN1 is essential for the efficient replication of telomeres through its …
Functional Significance Of Glycoprotein Clearance By The Asialoglycoprotein Receptor And The Mannose/Galnac-4-So4 Receptor, Lindsay Steirer Taylor
Functional Significance Of Glycoprotein Clearance By The Asialoglycoprotein Receptor And The Mannose/Galnac-4-So4 Receptor, Lindsay Steirer Taylor
All Theses and Dissertations (ETDs)
Glycosylation plays an important role in many biological functions. Two highly abundant, carbohydrate-specific, endocytic receptors reside in parenchymal and endothelial cells of the liver. Our lab has shown that the asialoglycoprotein receptor: ASGR) is capable of clearing glycoproteins bearing terminal Siaalpha2,6GalNAc as well as ones bearing terminal Gal/ GalNAc and that the Mannose/GalNAc-4-SO4 receptor: MR) is capable of clearing glycoproteins bearing terminal GalNAc-4-SO4. I am taking a genetic approach identifying endogenous ligands for the ASGR and the MR in vivo and establishing the biologic significance of clearing these glycoproteins from the blood. A number of glycosylated hormones such as luteinizing …
Computational And Experimental Investigation Of Allosteric Communication In The Transcriptional Regulator Nikr, Michael Bradley
Computational And Experimental Investigation Of Allosteric Communication In The Transcriptional Regulator Nikr, Michael Bradley
All Theses and Dissertations (ETDs)
The Ni2+ and DNA binding protein NikR is involved in nickel regulation in Escherichia coli through transcriptional repression of the NikABCDE nickel permease. NikR is a homotetramer and each chain contains both a DNA binding ribbon-helix-helix: RHH) domain and a Ni2+ binding regulatory ACT: aspartokinase, chorismate mutase, TyrA) fold. Work herein combines computational modeling of NikR structure with experimental studies aimed at understanding allosteric communication between the ACT and RHH domains. Hydrogen/deuterium exchange mass spectrometry shows a Ni2+ specific NikR conformational change relative to bound Cu2+, Co2+, and Zn2+. Concurrent coordination geometry and in vivo repressor function studies show that …
Expression Analysis And Stem Cell Engineering, Cara Rieger
Expression Analysis And Stem Cell Engineering, Cara Rieger
All Theses and Dissertations (ETDs)
The overall goal of the thesis was to develop tools to advance Investigations of stem cells in tissue engineering therapeutics for neurodegenerative disease and spinal cord injury. Two tools to characterize cell fate and a tool to separate a subset of neural cells were developed and evaluated. In the first study, a digital PCR technology, called polonies, was applied to measure mRNA from several key stem cell genes in small numbers of ES cells. Due to its properties, we hypothesized that polonies would be uniquely poised to profile stem cells. Polonies were counted for Oct3 in a sample of 10 …
Aggregation & Localization Of A Disease-Associated Prion Protein (Prp) Mutant, Andrea Rhonda Medrano
Aggregation & Localization Of A Disease-Associated Prion Protein (Prp) Mutant, Andrea Rhonda Medrano
All Theses and Dissertations (ETDs)
ABSTRACT OF THE DISSERTATION Aggregation & Localization of a Disease-Associated Prion Protein: PrP) Mutant by Andrea Rhonda Zaragoza Medrano Doctor of Philosophy in Biology and Biomedical Sciences: Genetics) Washington University in St. Louis, 2009 Professor David A. Harris, Chairperson Prion protein: PrP) is a GPI-anchored sialoglycoprotein involved in the pathogenesis of infectious and inherited forms of transmissible spongiform encephalopathies: TSEs). A nine-octapeptide insertional mutation in the prion protein: PrP) causes a fatal neurodegenerative disorder in both humans and transgenic mice. To determine the precise cellular localization of this mutant PrP: designated PG14), we have generated transgenic mice expressing PG14-EGFP, a …
Targeting The Dimerization Of Erbb Receptor Tyrosine Kinases, Rob Yang
Targeting The Dimerization Of Erbb Receptor Tyrosine Kinases, Rob Yang
All Theses and Dissertations (ETDs)
The epidermal growth factor receptor: EGFR) is a membrane receptor tyrosine kinase whose over-activation has been implicated to cause many human cancers. Novel strategies to inhibit the activation of EGF receptors other than the conventional antibody-based and tyrosine kinase inhibitors are virtually non-existent but could provide benefits both in the laboratory and clinical settings. In an effort to expand the current approaches, this thesis focused on targeting the homodimerization of the EGF receptors themselves and the heterodimerization of EGF receptors with the related ErbB2 receptor. Three sub-projects were completed in the process. The first project explored the feasibility of inhibiting …
Calling Cards For Dna-Binding Proteins, Haoyi Wang
Calling Cards For Dna-Binding Proteins, Haoyi Wang
All Theses and Dissertations (ETDs)
Organisms respond to their environment by altering patterns of gene expression. This process is orchestrated by transcription factors, which bind to specific DNA sequences near genes. In order to understand the regulatory networks that control transcription, the genomic targets of all transcription factors under various conditions and in different cell types must be identified. This remains a distant goal, mainly due to the lack of a high-throughput, in vivo method to study protein-DNA interactions. To fill this gap, I developed transposon "Calling Cards" for DNA-binding proteins. I endowed DNA binding proteins with the ability to direct the insertion of a …
Structural Rna Homology Search And Alignment Using Covariance Models, Eric Nawrocki
Structural Rna Homology Search And Alignment Using Covariance Models, Eric Nawrocki
All Theses and Dissertations (ETDs)
Functional RNA elements do not encode proteins, but rather function directly as RNAs. Many different types of RNAs play important roles in a wide range of cellular processes, including protein synthesis, gene regulation, protein transport, splicing, and more. Because important sequence and structural features tend to be evolutionarily conserved, one way to learn about functional RNAs is through comparative sequence analysis - by collecting and aligning examples of homologous RNAs and comparing them. Covariance models: CMs) are powerful computational tools for homology search and alignment that score both the conserved sequence and secondary structure of an RNA family. However, due …
Subunit Compositions Of Arabidopsis Dna-Dependent Rna Polymerases And The Roles Of The Plant-Specific Rna Polymerases Iv And V In Gene Silencing, Thomas Ream
All Theses and Dissertations (ETDs)
In addition to RNA polymerases I, II and III, the essential RNA polymerases present in all eukaryotes, plants have two additional nuclear RNA polymerases, abbreviated as Pol IV and Pol V, that play non-redundant roles in siRNA-directed DNA methylation and gene silencing. Using a combination of affinity purification and protein identification by mass spectrometry, my studies show that Arabidopsis Pol IV and Pol V are composed of subunits that are paralogous or identical to the twelve subunits of Pol II. Four subunits of Pol IV are distinct from their Pol II paralogs, six subunits of Pol V are distinct from …