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An Epidemiological Study Of Campylobacter Populations Reveals A Selective Pressure By Roxarsone, Sean Jeffery Pendleton

Doctoral Dissertations

Whole genome sequencing (WGS) is the most discriminatory of typing methods and can provide additional information including virulence, antigen targets for vaccine development, and antimicrobial resistance profiles. The first part of this study aimed to determine the application of WGS as a genotyping method for Campylobacter by comparing WGS to two commonly used genotyping methods, Pulsed-field gel electrophoresis (PFGE) and flaA typing. Five Campylobacter strains isolated from conventional and organic poultry, and five additional isolates with published genomes were compared using the three methods. A total of 8 PFGE patterns and 8 flaA alleles were identified from the 10 strains. …

Jab1 Negatively Regulates Pten And Promotes Resistance To Trastuzumab In Her2-Positive Breast Cancer, Thuy T. Vu

Dissertations & Theses (Open Access)

HER2-positive breast cancer, which is characterized by the over-expression of the HER2 onco-protein, accounts for approximately 20% of all breast cancer cases. Trastuzumab (Herceptin), the first targeted therapy approved for HER2-positive disease, potently prevents the activation of signaling pathways downstream of HER2 and significantly improves patients’ outcomes. However, resistance to trastuzumab is inevitable; such resistance can occur through reduced expression of PTEN protein.

Jab1 is over-expressed in 50% of primary cancers and 90% of metastatic tumors. Our lab previously showed that depletion of Jab1 in combination with trastuzumab treatment up-regulated PTEN in mouse xenografts refractory to trastuzumab. PTEN was not …

Bi-Directional Signaling Between Melanoma And The Microenvironment Generates A Protective Niche That Mediates Therapeutic Escape, Inna Fedorenko

USF Tampa Graduate Theses and Dissertations

Very few cancer patients are cured through drug therapy alone, with the majority exhibiting acquired resistance. To date, most studies of therapeutic escape have focused upon tumor-intrinsic mechanisms of drug resistance with little attention paid to the role of normal host cells in preventing complete tumor eradication. In the present study we implicate co-operative bi-directional signaling between melanoma cells and fibroblasts in the generation of a pro-survival niche that mediates drug resistance. Mass-spectrometry based phosphoproteomics was used to show that BRAF inhibition and chemotherapy drugs enhanced the survival of both melanoma cells and fibroblasts through the induction of fibronectin (FN)/integrin …

Potential Targeted Therapeutic Strategies For Overcoming Resistance In Braf Wild Type Melanoma, Vito William Rebecca

USF Tampa Graduate Theses and Dissertations

Melanoma manifests itself from the malignant transformation of melanocytes and represents the deadliest form of skin cancer, being responsible for the disproportionate majority of all skin cancer deaths. The 2002 discovery that 50% of all melanoma patients possess activating BRAF mutations ignited a significant paradigm shift in the way the melanoma field approached research and how patients were treated [1]. The era of targeted therapy had begun and with it came successful targeted BRAF inhibitor therapy regimens, which have accomplished improved clinical benefit (response rate, progression free survival, and overall survival) compared with treatment with chemotherapy in three phase III …

Mapping Quantitative Trait Loci Associated With Alternaria Leaf Blight Resistance And Elemental Sulfur Tolerance In Melon, James Daley

All Theses

Melon (Cucumis melo L.) production is significantly affected by Alternaria leaf blight, caused by Alternaria cucumerina. Fungicide application is the primary control method; however, this could be mitigated through the increased use of resistant varieties. USDA-ARS breeding line MR-1 has been shown to have a high level of resistance to Alternaria cucumerina. However, molecular markers linked MR-1 Alternaria resistance have yet to be identified. In order in identify QTL associated with Alternaria resistance MR-1 x Ananas Yokneum (AY) derived recombinant inbred lines (RILs) were phenotyped using a modified wounded-leaf assay. Elemental sulfur is an effective fungicide for several foliar pathogens …

Antimicrobial Resistance Of Channel Catfish Intestinal Microflora In The Arkansas And Ninnescah Rivers In Kansas, Jordan R. Hofmeier

Master's Theses

Antimicrobial compounds have been used by humans to counteract bacterial infections since 1910. Overuse of these compounds in clinical and agricultural applications has led to rapid evolution and global spread of antimicrobial resistance and rivers are the main receiving body for antimicrobials and resistant bacteria from urban effluents and agricultural runoff. When antimicrobial-resistant bacteria enter the aquatic environment, water acts as a physical pathway for their distribution. Subsequently, resistance genes become established in natural systems and pose threats to human health and ecological processes. Due to these potential threats, antimicrobial resistance in the aquatic environment should be closely monitored. To …

Fungicide Resistance In Botrytis Cinerea From Strawberry - Molecular Mechanisms And Management, Anja Grabke

All Theses

The United States is the largest producer of strawberries worldwide, generating approximately $2.4 billion worth of fruit each year. Strawberry production, however, is often threatened by pathogens. One of the most destructive fungal pathogens is Botrytis cinerea, the causal agent of gray mold disease. The control of gray mold in commercial fields is largely dependent on the application of fungicides, including the dicarboximide iprodione and the hydroxyanilide fenhexamid. Because both fungicides are prone to resistance development, a survey was conducted to determine the occurrence and prevalence of fungicide resistance. Single-spore isolates were collected from strawberry fields in Florida (for …

Forest Net Primary Production Resistance Across A Gradient Of Moderate Disturbance, Ellen Goodrich-Stuart

Theses and Dissertations

The global carbon (C) balance is vulnerable to disturbances that alter terrestrial C uptake and loss. Moderate disturbances that kill or defoliate only a subset of canopy trees such as insect defoliation, drought, and age-related senescence are increasing in extent and frequency; yet, little is known about the effect of moderate disturbance on forest production and the mechanisms sustaining or supporting the recovery of the C cycle across a range of moderate disturbance severities. We used a broad plot-scale gradient of upper canopy tree mortality within a large manipulation of forest disturbance to: 1) quantify how aboveground wood net primary …

Towards The Development Of Ash Varieties Resistant To Emerald Ash Borer, Lindsay Ann Kolich

Open Access Theses

The emerald ash borer (EAB; Agrilus planipennis Fairmaire) (Coleoptera: Buprestidae) is a destructive invasive beetle from Asia which has killed millions of ash trees (Fraxinus spp.) throughout North America. This phloem-feeding borer is capable of killing otherwise healthy trees and colonizes trees as small as saplings - most affected trees die within four years of colonization. Asian ash species (i.e., Manchurian and Chinese) appear to be more resistant to EAB than those native to North America (e.g., green, white, and black ash). In this project we use reciprocal and conspecific grafts of these five ash species to determine the …

Role Of The Pkna And Pknb Kinases In Mycobacterium Tuberculosis, Tripti Anandan

Wayne State University Dissertations

To respond to environmental changes, M. tuberculosis possesses eleven "eukaryotic-type" Ser/Thr protein kinases. The aim of the study described in this dissertation was to identify role of two of these kinases; PknA and PknB that are essential in M. tuberculosis. Two approaches are described to screen for potential in vivo substrates of PknA/PknB. First approach is based on proteomic search by over-expressing PknA/PknB in M. tuberculosis. Proteomic search led to identification of proteasome to be a substrate of PknA and PknB in M. tuberculosis. Furthermore, I demonstrate that the phosphorylation of PrcA and PrcB by PknA regulates processing of Pre-PrcB. …

Resistance Of Fall Armyworm, Spodoptera Frugiperda (J.E. Smith) To Bacillus Thuringiensis, Ying Niu

LSU Master's Theses

The fall armyworm, Spodoptera frugiperda (J.E. Smith), is a target pest of Bacillus thuringiensis (Bt) corn in North and South America. In this study, multiple tests were conducted in the laboratory and greenhouse to 1) determine the susceptibility of two field populations of S. frugiperda collected from Florida (FL) and Puerto Rico (PR) to purified Cry1F protein and Bt corn leaf tissue and 2) evaluate larval survival of and plant injury by Cry1F-susceptible, -resistant, and –heterozygous genotypes of S. frugiperda on whole plants of transgenic corn containing single and pyramided Bt genes. Corn hybrids evaluated in this study included five …

Screening For Resistance To Sugarcane Brown Rust With Controlled Conditions Inoculation, Mavir Carolina Avellaneda Barbosa

LSU Master's Theses

Brown rust, caused by Puccinia melanocephala, is an important disease of sugarcane. Breeding for host plant resistance is the primary control measure. Screening for resistance has relied on rating the severity of symptoms caused by natural infection; however, erratic results make this method problematic. A method accomplishing both infection and disease expression under controlled conditions could avoid the problems associated with resistance evaluations under natural infection. Inoculation of seedlings was evaluated to determine whether it could provide accurate resistance ratings in cross appraisal, and inoculation under controlled conditions was evaluated for the potential to accurately determine resistance reactions in clones …