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Full-Text Articles in Life Sciences

Modulation Of Rho Termination : Expectation Vs Reality, Kavya Sri Sai Chegireddy Dec 2021

Modulation Of Rho Termination : Expectation Vs Reality, Kavya Sri Sai Chegireddy

Legacy Theses & Dissertations (2009 - 2024)

Transcription termination factor Rho is an essential protein in many bacteria. Rho is an ATP-dependent RNA helicase that accounts for 20-50% of termination events in Escherichia coli and plays an important role in preventing pervasive transcription that otherwise might be lethal to bacteria. Rho termination usually occurs in the 3’ UTRs and non-coding regions of the DNA, and the actively transcribing RNA is believed to be protected by translating ribosomes from Rho termination since both transcription and translation are a simultaneous process in prokaryotes. However, in reality, Rho terminates transcription of some protein-coding genes, and fails to terminate transcription of …


Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi Aug 2021

Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi

Legacy Theses & Dissertations (2009 - 2024)

MicroRNA (miRNA), as a distinct class of biological regulators and a ”guide” member of non-coding RNA-protein complexes (RNPs), regulates more than 60% of protein-coding genes expression through base-pairing with targeted messenger RNA (mRNA) in the RNA-Induced Silencing Complex (RISC). Most of miRNAs identified in human, are conserved in other animals, which have preferentially conserved interaction sites particularly in 3’ untranslated regions (3’UTRs) of many human messenger mRNAs.The capability of a single miRNA to target more than hundreds of mRNAs, suggests that miRNAs influence essentially all developmental process and diseases, which also makes them interesting candidates as therapeutics agents. The primary …


Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi Aug 2021

Molecular Simulation Of Rna Conformational Dynamics : An Example Of Micro-Rna Targeting Messenger Rna : Mir-34a-Msirt1, Parisa Ebrahimi

Legacy Theses & Dissertations (2009 - 2024)

MicroRNA (miRNA), as a distinct class of biological regulators and a ”guide” member of non-coding RNA-protein complexes (RNPs), regulates more than 60% of protein-coding genes expression through base-pairing with targeted messenger RNA (mRNA) in the RNA-Induced Silencing Complex (RISC). Most of miRNAs identified in human, are conserved in other animals, which have preferentially conserved interaction sites particularly in 3’ untranslated regions (3’UTRs) of many human messenger mRNAs.The capability of a single miRNA to target more than hundreds of mRNAs, suggests that miRNAs influence essentially all developmental process and diseases, which also makes them interesting candidates as therapeutics agents. The primary …


Ampa And Kainate Receptor-Potentiating Rna Aptamers, Janet L. Lynch May 2021

Ampa And Kainate Receptor-Potentiating Rna Aptamers, Janet L. Lynch

Legacy Theses & Dissertations (2009 - 2024)

Glutamate receptors act to bring about excitatory transmission in the central nervous system. The receptors are divided into two groups: ionotropic and metabotropic glutamate receptors. Ionotropic glutamate receptors are ion channels which are activated by an agonist such as glutamate or kainate. The main receptors in the ionotropic glutamate receptor family are the α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-D-aspartate (NMDA) receptors. In the central nervous system ionotropic glutamate receptors are found both pre- and postsynaptically. It has been found that most AMPA and NMDA receptors are postsynaptic receptors while the kainate receptors can be pre- or postsynaptic. Underactivity of these …


Characterization Of A Putative Helicase In Rifampicin Resistance Of Mycobacterium Abscessus:, Aavrati Saxena May 2021

Characterization Of A Putative Helicase In Rifampicin Resistance Of Mycobacterium Abscessus:, Aavrati Saxena

Legacy Theses & Dissertations (2009 - 2024)

Mycobacterium abscessus (Mab), a non-tuberculous environmental mycobacterium is one of the emerging pathogens. The number of Mab infections has doubled in the past decade. It is also an opportunistic pathogen usually infecting immunocompromised individuals and causing numerous skin and soft tissue infections. It commonly causes lung infections in people who are already infected with one or other lung infections such as tuberculosis. The treatment of Mab infections is difficult because of its intrinsic resistance to most of the antibiotics available. This project studies Rifampicin (RIF) resistance in Mab, as RIF is a well-established treatment for other mycobacterial infections including tuberculosis, …


Study Of Primary Cilium Structure And Intraflagellar Transport, Shufeng Sun Jan 2021

Study Of Primary Cilium Structure And Intraflagellar Transport, Shufeng Sun

Legacy Theses & Dissertations (2009 - 2024)

Primary cilia are hair-like protrusions that stem from the basal bodies in the cytoplasm and extend into the extracellular space to sense signals. Intraflagellar transport (IFT) functions to transport cargo molecules into and out of the ciliary compartment to assemble, maintain, and disassemble the cilia. Accurate knowledge of the three-dimensional (3D) structure of primary cilia and precise details of the IFT profile is the foundation for understanding the sensory functions of primary cilia. This work covers three aspects of primary cilia. Firstly, we obtained and analyzed the overall 3D architecture of the complete primary cilia axoneme region using serial section …


Kinetic Characterization Of Two C-Family Polymerases From The Gram-Positive Bacterium Staphylococcus Aureus, Sean P. Fagan Jan 2021

Kinetic Characterization Of Two C-Family Polymerases From The Gram-Positive Bacterium Staphylococcus Aureus, Sean P. Fagan

Legacy Theses & Dissertations (2009 - 2024)

In this dissertation, I review the fundamental processes and mechanisms for bacterial DNA replication, especially the mechanisms employed by high-fidelity DNA polymerases to replicate the genome. Unlike the prototypical bacterial system from Escherichia coli which uses a single C-family polymerase, DNA polymerase IIIα (Pol IIIα), to replicate the genome, low-GC content Gram-positive bacteria utilize two essential C-family polymerases, PolC and DnaE. PolC and DnaE work cooperatively to replicate the genome, with DnaE initiating synthesis from RNA-primers and PolC performing the bulk synthesis. Although atomic structures of both PolC and Pol IIIα are available, detailed pre-steady state kinetic analysis of the …


Development Of Chemical Methods For Oligonucleotide Purification, Paramagnetic Labeling And Synthesis Of Dna-Based Advanced Materials, Muhan He Jan 2021

Development Of Chemical Methods For Oligonucleotide Purification, Paramagnetic Labeling And Synthesis Of Dna-Based Advanced Materials, Muhan He

Legacy Theses & Dissertations (2009 - 2024)

This thesis describes a chemical method for alternative oligonucleotide purification that is non-chromatographic and gel-free and allows to routinely synthesize and purify long functional RNA strands. The purification of long RNAs is based on the bio-orthogonal inverse electron demand Diels-Alder (IEDDA) chemistry between trans-cyclooctene (TCO) and tetrazine (Tz). Target oligonucleotide strands are selectively tagged with Tz and can be captured and purified from the failure sequences with immobilized TCO. RNA strands are synthesized on solid support through a photolabile linker to avoid the loss of Tz tag. Purity of the isolated oligonucleotides was evaluated using gel electrophoresis, HPLC and mass …


The Phosphodiesterase, Rv0805, Is An Unheralded Component Of Tb Complex Mycobacterial Physiology In And Beyond Camp Homeostasis, James R. Mcdowell Jan 2021

The Phosphodiesterase, Rv0805, Is An Unheralded Component Of Tb Complex Mycobacterial Physiology In And Beyond Camp Homeostasis, James R. Mcdowell

Legacy Theses & Dissertations (2009 - 2024)

Phosphodiesterases (PDEs) are integral components of 3’,5’-cyclic adenosine monophosphate (cAMP) signaling pathways by degrading cAMP to modulate the concentration, duration, and localization of the cAMP signal which maintains the specificity of cAMP pathways. The human pathogen, Mycobacterium tuberculosis (Mtb) has a unique cAMP network architecture with at least 15 adenylyl cyclases (ACs) that generate cAMP, but only one characterized PDE, Rv0805, which is found exclusively in pathogenic mycobacteria. Rv0805 can influence Mtb cAMP levels but the absence of Rv0805 orthologs in non-pathogenic mycobacteria and apparent separation of Rv0805 from cAMP directed roles led to numerous questions surrounding PDE function in …


Retrotransposon-Mediated Transduction Of An Environmental Cue To Regulate Centrosome Fate, Shawn Patrick Murphy Jan 2021

Retrotransposon-Mediated Transduction Of An Environmental Cue To Regulate Centrosome Fate, Shawn Patrick Murphy

Legacy Theses & Dissertations (2009 - 2024)

In 1969, the enrichment of mobile element repeat sequences led Britton and Davidson to propose the hypothesis that gene expression in higher eukaryotes is regulated through the exaptation of mobile elements. In this work, I have explored the hypothesis that mobile elements can also be harnessed by the host to regulate asymmetric cell division, thereby determining cell fate. Retrotransposons are ubiquitous eukaryotic mobile elements that transpose through an RNA intermediate. They are often active in cell types that divide asymmetrically to yield daughter cells with different fates, such as embryonic stem cells, germline stem cells, neuronal stem cells and the …


Pre-Steady-State Kinetic Characterization Of An Antibiotic-Resistant Mutation Of Staphylococcus Aureus Polc, Rachel Alice Nelson Jan 2021

Pre-Steady-State Kinetic Characterization Of An Antibiotic-Resistant Mutation Of Staphylococcus Aureus Polc, Rachel Alice Nelson

Legacy Theses & Dissertations (2009 - 2024)

In this dissertation I provide a pre-steady-state kinetic characterization of an antibiotic-resistant mutant of a Staphylococcus aureus DNA polymerase. Staphylococcus aureus is one of the most common causes of infections in humans, and is widely known for its ability to acquire resistance to most antibiotics. Staphylococci infections pose a significant burden to the healthcare system and increase mortality, as more than 95% of Methicillin-Resistant S. aureus (MRSA) infections do not respond to first-line antibiotics. The limited treatment options for Staphylococci infections underscores the need for novel, alternative strategies. In this thesis, I discuss 6-anilinouracils (6-AU), a family of potent dGTP …


Identification Of Ires Activity In Cellular Mrnas And Viral Rna Using A Circular Rna Construct, Priyanka Sehta Jan 2021

Identification Of Ires Activity In Cellular Mrnas And Viral Rna Using A Circular Rna Construct, Priyanka Sehta

Legacy Theses & Dissertations (2009 - 2024)

Translation initiation is a critical step in the process of protein synthesis. The canonical way of translation initiation involves ribosomes being recruited to the 7-methyl guanosine cap present at the 5’end of the untranslated region (5’ UTR) of the RNAs. However, viral RNAs and some cellular mRNAs lack this 5’ cap structure and thus deploy an alternate non-canonical translation initiation mechanism. In non-canonical translation initiation, ribosome recruitment is facilitated by the RNA secondary structures called Internal Ribosome Entry Site (IRES) present most often in the 5’ UTR. To measure IRES-mediated translation, the dual luciferase assay has been the gold standard. …


Missense Mutations In The Gamma Crystallins And Mechanisms Of Lens Opacity, Wenjuan Hou Jan 2021

Missense Mutations In The Gamma Crystallins And Mechanisms Of Lens Opacity, Wenjuan Hou

Legacy Theses & Dissertations (2009 - 2024)

Cataract, or clouding of the ocular lens, among the most common types of eye diseases, is the leading cause of blindness worldwide. With the opacity or clouding of the lens, light incident on the lens is scattered rather than being transmitted and is thus prevented from focusing on the retina. The lens becomes cataractous due to a large number of reasons, among which aging and genetic mutations are two of the most common factors. Clouding of the center of the lens or nuclear opacity, is the most frequently observed type of age-onset cataract, as well as inherited, congenital cataract [1, …


Role Of Rna Helicases In The Drosophila Germline, Patrick Blatt Jan 2021

Role Of Rna Helicases In The Drosophila Germline, Patrick Blatt

Legacy Theses & Dissertations (2009 - 2024)

Gametogenesis, the process of creating egg or sperm, is required for launching successive generations of sexually reproducing organisms. The developmental milestones that occur during gamete production have been studied for decades and are of critical interest to gain insight to conserved features of human fertility. Drosophila has been used for over a century as an efficient research model and remains pivotal in uncovering fundamental biological paradigms. During Drosophila egg production, or oogenesis, several developmental transitions must be traversed to ensure completion of oogenesis including: Germline Stem Cell (GSC) maintenance and differentiation, mitotic and meiotic cell divisions, and production of maternally …


Host Factors Affecting Group Ii Intron Retrotransposition, Justin Michael Waldern Jan 2021

Host Factors Affecting Group Ii Intron Retrotransposition, Justin Michael Waldern

Legacy Theses & Dissertations (2009 - 2024)

Group II introns are self-splicing mobile elements that are thought to be the evolutionary ancestors of eukaryotic retrotransposons, the spliceosome, and spliceosomal introns. Yet, little is known about how group II introns have coevolved within their native hosts or about the corresponding host biology.Using the Ll.LtrB intron in its native host, Lactococcus lactis, I first sought to identify host factors that influence retrotransposition. Since retrotransposition can be costly to the host organism, group II introns must achieve a delicate balance between self-proliferation and host preservation. By utilizing the native host organism, my goal was to unearth retrotransposition-related mechanisms that have …