Bioinformatics Commons^™

Differences In Plant Hormone Responses Between Arabidopsis Thaliana And Schrenkiella Parvula Facing Lithium Toxicities, Jifeng Li

LSU Doctoral Dissertations

Investigating stress responses in plants is central to plant development studies and crop research. Identifying mechanisms of plant abiotic stress tolerance and adaptation will be keys to relieve the conflict between an increasing global population and declining agronomic land. Studies on extremophytes and their genetic responses to environmental stress are a way to help understand how and why these extremophile plants can develop well under extreme environments including high salinity and heavy metal toxicity. The studies herein first focus on comparative responses at the genetic level to lithium toxicity between Arabidopsis thaliana and Schrenkiella parvula. Based on elemental quantification …

Understanding Potassium Toxicity Stress Responses Of The Extremophyte Schrenkiella Parvula Using Systems Biology Approaches, Pramod Pantha

LSU Doctoral Dissertations

Schrenkiella parvula is an extremophyte model closely related to Arabidopsis thaliana and Brassica crops. Its natural habitat includes shores of saline lakes in the Irano-Turanian region. It has adapted to grow in soils rich in multiple salts including Na⁺ and K⁺. I have investigated the genetic basis for high K⁺ tolerance in plants using S. parvula as a stress tolerant model compared to the premier plant model, Arabidopsis thaliana which is highly sensitive to salt stresses using physiological, ionomic, transcriptomic, and metabolomic approaches. Under high K⁺ stress, root system architecture changes significantly compared to control …

Genomic Studies Of Beaf-32 In Drosophila, John Keller Mckowen Iii

LSU Doctoral Dissertations

Compared to humans, the model organism Drosophila melanogaster is particularly gene dense and encodes several insulator binding proteins (IBP) to aid in its genome organization. Our focus of research is a particular IBP, Boundary Element-Associated Factor of 32kD (BEAF). BEAF primarily binds near the promoters of constitutively active housekeeping genes. It is thought to help maintain the active state of these genes by preventing the spread of repressive chromatin. Additionally, the enhancer blocking activity of BEAF is thought to prevent aberrant activation or silencing of genes. BEAF appears to be ubiquitously expressed among cells and tissues, albeit at varying levels. …

Quantifying Structure And Variation In Complex Phylogenetic Data, Genevieve Geraldine Mount

LSU Doctoral Dissertations

Identifying the source and structure of variation in nature is crucial to understanding fundamental aspects of evolution. Despite a recent plethora of genetic and morphological data, many interesting questions about the relationships between different groups remain unresolved. My dissertation evaluates three approaches for identifying and quantifying the variation within phylogenetic datasets. Characterizing variation within datasets and across analytical methods gives insight into biologically interesting characters, unusual evolutionary processes, and areas for model improvement.

Network-based community detection approaches offer a powerful tool to describe variation in phylogenetic signal across the genome (i.e., gene tree variation). In Chapter 2, I investigate the …

Computational Analysis Of Papionini Evolution Using Alu Insertions, Vallmer Edward Jordan Ii

LSU Doctoral Dissertations

Alu elements are primate specific retrotransposons that have remained active throughout the course of primate evolution. As a result of this sustained mobilization. Alu elements are present in greater copy number in primate genomes than any other transposable element. An average of over one million Alu elements has been identified in every sequenced haplorrhine genome to date. These characteristics qualify Alu elements as ideal characters for studying evolutionary relationship among primates.

The increasing availability of whole genome sequencing data presents novel challenges and opportunities for comparative genomic analyses. Genomic data is now publicly available for most primate species. Such an …

The Determinants Of Nucleosome Patterns And The Impact Of Phosphate Starvation On Nucleosome Patterns And Gene Expression In Rice, Qi Zhang

LSU Doctoral Dissertations

In eukaryotic cells, DNA is a large molecule that must be greatly condensed to fit within the nucleus. DNA is wrapped around histone proteins to form nucleosomes, which facilitate DNA condensation, but on the other hand, may limit DNA processes. Organisms must respond to environmental stress in order to survive, and one strategy is by remodeling nucleosomes to promote changes in DNA accessibility to alter gene expression. Studies have demonstrated a clear correlation between nucleosome dynamics and transcriptional change in some eukaryotes, however factors that affect nucleosome positioning in plants are largely unknown, and the correlation between nucleosome dynamics and …