Life Sciences Commons^™

The Role Of The Suppressor Of Hairy-Wing Insulator Protein In Chromatin Organization And Expression Of Transposable Elements In Drosophila Melanogaster, Heather Anne Wallace

Doctoral Dissertations

ABSTRACT Chromatin insulators are required for proper temporal and spatial expression of genes in metazoans. Insulators are thought to play an important role in the regulation of gene expression through the formation of higher-order chromatin structures. One of the best characterized insulators is the Drosophila gypsy insulator, which is located in the gypsy retrovirus. Several proteins are required for gypsy insulator function, including Su(Hw), Mod(mdg4), and CP190. In addition to the gypsy insulator, these proteins are located throughout the genome at sites which are thought to correspond to endogenous insulators. Analysis of the distribution of insulator proteins across a region …

“Development Of Genetic And Genomic Predictors Of Fertility In Argentinean Holstein Cattle.”, Fernando Alfonso Di Croce

Doctoral Dissertations

The overall aim of the studies described herein was to evaluate genetic variation in cattle fertility traits for development of genetic and genomic predictors in breeding strategies. Results from these experiments suggest that improvements in fertility through genetic selection are a possible approach to increase reproductive efficiency. Experiment 1 evaluated the development of genetic parameters associated with multiple ovulation and embryo transfer schemes in an attempt to assist producers in identifying animals with greater genetic merit for these protocols. This study confirmed that genetic selection of donors or sires appears to be a potential approach to improve efficiency of MOET …

Steps Toward Butternut (Juglans Cinerea L.) Restoration, Sunshine L. Brosi

Doctoral Dissertations

Butternut (Juglans cinerea L.), a lesser-known relative of black walnut (Juglans nigra L.), is a native tree species beneficial for wildlife, valuable for timber, and part of the great diversity of species in the eastern forests of North America. Populations of butternut are being devastated by butternut canker disease, caused by the fungus Sirococcus clavigignenti-juglandacearum (V.M.G. Nair, Kostichka, & Kuntz), which is thought to be introduced to North America. The disease causes multiple branch and stem cankers that eventually girdle trees. Small population sizes, lack of sprouting, and shade intolerance exacerbates the disease and results in permanent losses of butternut …

Characterizing The Role Of Dna Repair Proteins In Telomere Length Regulation And Maintenance: Fanconi Anemia Complementation Group C Protein And 8-Oxoguanine Dna Glycosylase, David Beomjin Rhee

Doctoral Dissertations

Telomeres are the chromosome end structures consisting of telomere-associated proteins and short tandem repeat sequences, TTAGGG, in humans and mice. Telomeres prevent chromosome termini from being recognized as broken DNA ends. The structural integrity of DNA including telomeres is constantly threatened by a variety of DNA damaging agents on a daily basis. To counteract the constant threats from DNA damage, organisms have developed a number of DNA repair pathways to ensure that the integrity of genome remains intact. A number of DNA repair proteins localize to telomeres and contribute to telomere maintenance; however, it is still unclear as to what …

Translational Regulation In Arabidopsis Thaliana: Genetic And Functional Characterization Of Eukaryotic Initiation Factor 3, Bijoyita Roy

Doctoral Dissertations

Molecular functions of eukaryotic initiation factor 3 (eIF3) in translation are manifold, encompassing events from initiation complex assembly to translation termination. The contribution of the individual subunits of eIF3 to its multiple activities is quite unclear. It has been hypothesized that several of its 13 subunits contribute to mRNA specific regulation. Prior research had established that the h subunit of eIF3 in Arabidopsis was required for translation of specific mRNAs as well as for organ formation and meristem development. This study aims towards understanding the functions of individual subunits of eIF3 in the context of plant development and to further …

Methicillin Resistance In Staphylococcus Pseudintermedius, Chad Christopher Black

Doctoral Dissertations

Staphylococcus pseudintermedius affecting dogs is analogous to S. aureus on humans, acting as both normal flora and opportunistic pathogen. Methicillin resistance in S. pseudintermedius is recent, with the first documented occurrence of an isolate bearing the methicillin resistance gene, mecA, in 1999. This gene encodes penicillin binding protein 2a, which renders all beta-lactam drugs ineffective and functions as a “gateway” antibiotic resistance determinant. In the presence of ineffective antibiotics, opportunities for mutational events and acquisition of mobile genetic elements increase as microbial densities increase, often leading to multi-drug resistance. Methicillin-resistant S. pseudintermedius (MRSP) infections have become increasingly common. For …

The Maximum Clique Problem: Algorithms, Applications, And Implementations, John David Eblen

Doctoral Dissertations

Computationally hard problems are routinely encountered during the course of solving practical problems. This is commonly dealt with by settling for less than optimal solutions, through the use of heuristics or approximation algorithms. This dissertation examines the alternate possibility of solving such problems exactly, through a detailed study of one particular problem, the maximum clique problem. It discusses algorithms, implementations, and the application of maximum clique results to real-world problems. First, the theoretical roots of the algorithmic method employed are discussed. Then a practical approach is described, which separates out important algorithmic decisions so that the algorithm can be easily …

Investigating Genetic Diversity Of Phytophthora Spp. And Related Oomycetes, Jonathan Patrick Hulvey

Doctoral Dissertations

Oomycetes, like fungi, are filamentous heterotrophs, but unlike true fungi are diploid and share a photosynthetic ancestor. Many of these organisms are plant and animal pathogens, and members of the genus Phytophthora cause devastating disease on a diverse array of agricultural plant hosts. Several diverse topics in oomycete biology are investigated in this dissertation. Chapter 2 is a report on loss of heterozygosity in Phytophthora capsici in response to chemical mutagenesis.The research presented in Chapters 3 and 4 are centered on documenting biodiversity and genetic diversity of populations of Phytophthora species obtained from infected plant hosts. The final chapter (Chapter …

The Functional Role Of The Drosophila Gypsy Insulator In The Regulation Of Gene Expression, Hyuck Joon Kang

Doctoral Dissertations

Chromatin insulators are short DNA sequences that, together with enhancers and silencers, orchestrate gene transcription through DNA-protein interactions in eukaryotic genomes. It has been proposed that insulators operate at the chromatin level by generating functionally independent higher-order chromatin domains. Insulators may maintain the integrity of such domains using two properties: blocking enhancer-promoter interactions and blocking heterochromatin spreading. The gypsy insulator of Drosophila was identified as a region of the gypsy retrovirus responsible for the production of tissue-specific mutations in many genes. The Suppressor of Hairy wing [Su(Hw)] protein contains 12 zinc fingers that specifically bind the gypsy insulator. Upon DNA …

A Systems Genetics Approach To The Characterization Of Differential Low Dose Radiation Responses In Bxd Recombinant Inbred Mice, Rachel Marie Lynch

Doctoral Dissertations

High doses of radiation (HDR) are clearly detrimental to human health, but relatively little is known about the health consequences following exposure to low doses of radiation (LDR, <10cGy). Understanding the risks associated with LDR is of great importance to the general public due to the recent dramatic increase in diagnostic radiological imaging. While HDR clearly suppress immune function, there is evidence that LDR can be immunostimulatory. Within the organism, defining the consequences of LDR is further complicated by the impact of genetic background, particularly in systems such as the immune system for which both radiosensitivity and genetic effects are profound.

We addressed the issue of genetic susceptibility to LDR using the immune system as a target system and treated the LDR response as a complex trait analyzed using a systems genetics framework. Using the BXD recombinant inbred strain mouse panel as a genetic reference population allowed us to address the radiation response within the context of natural genetic variation. Our overarching hypothesis is that, within a population, the immunological effects of LDR …

Evaluation Of Genetic Diversity Of Flowering Dogwood (Cornus Florida L.) In The Eastern United States Using Microsatellites., Denita Hadziabdic

Doctoral Dissertations

Flowering dogwood (Cornus florida L.) populations have experienced severe declines caused by dogwood anthracnose in the past three decades. Mortality has ranged from 48 to 98%, raising the concern that genetic diversity of this native tree has been reduced significantly. Microsatellite data were used to evaluate the level and distribution of genetic variation throughout much of the native range of the tree. In the first conducted study, we found that genetic variation in areas affected by anthracnose was as high as or higher than areas without die-offs. We found evidence of four widespread, spatially contiguous genetic clusters. However, there was …

Reverse Genetic And Cell Biological Approaches To The Study Of Developmental Functions Of Class Xi Myosin In Arabidopsis Thaliana, Eunsook Park

Doctoral Dissertations

Myosin proteins function as molecular motors that drive the ATP-dependent movement of cellular components along actin filaments. Vascular plants encode two different types of myosin, referred to as class VIII and class XI. Although class XI myosins have been suggested to function in organelle movement and cytoplasmic streaming, little is known about their cellular function in detail.

The Arabidopsis genome encodes 13 class XI myosin genes. The reasons for the relatively large number of myosin XI isoforms present within a single plant species are unknown. To investigate the function of these gene products in the cell, we determined the spatial …