Life Sciences Commons^™

Impact Of Dietary Modification On Aflatoxicosis In Poultry, Xi Chen

Open Access Dissertations

Aflatoxin contamination in feed and feed ingredients is of high worldwide prevalence, posing serious risks to the livestock industry. A series of studies were conducted to better understand the comprehensive impact of aflatoxicosis and its interrelationships with dietary modifications in broiler chicks and ducks. Results of these studies emphasize the many factors that the severity of aflatoxicosis depends on, including animal species, age, presence of mycotoxin adsorbent, and concentration of major dietary nutrients. Exposure to 2 mg/kg cultured AFB1 led to reduced feed intake, BW gain, depressed feed efficiency, increased relative liver weight, negatively affected serum measures and complement activity, …

Utilization Of Ferrioxamine Microarrays For The Rapid Detection Of Pathogenic Bacteria, Nigam Bir Arora

Open Access Dissertations

Siderophores are low-molecular weight species utilized by bacteria for the sequestration of iron, an essential nutrient. Siderophores and their cognate receptors are considered to be virulence factors, due to their prominent role in pathogenicity. The work presented here focuses on ferrioxamine (FOx) as an “immutable” ligand for pathogen detection. A number of bacterial strains expressing high-affinity FOx receptors were identified by a proteomic BLAST search, and screened against microarrays patterned with FOx conjugates for detection using label-free optical imaging. Aspects such as inkjet printing and surface chemistry, iron-limiting conditions and bacterial selection protocols, and linker conjugate design were addressed and …

Modeling For Thermal Resistance Of Non-O157 Shiga Toxin Producing Escherichia Coli In Ground Beef, Jagpinder S. Brar

Open Access Dissertations

Predictive models in microbiology are used for estimating the growth or survival of microorganism in a set of environmental conditions. A validated predictive model provides an alternative to extensive survival and shelf life studies. In this study, a predictive inactivation model for non-O157 shiga toxin producing Escherichia coli (STEC) in ground beef was developed. Six strains of non-O157 STEC; E. coli O26:H1, E. coli O45:H2, E. coli O103:H2, E. coli O111:H8, E. coli O121:H9, and E. coli O145: nonmotile, has similar pathogenicity as E. coli O157:H7 and can cause serious food borne illnesses. These pathogens are considered as an adulterant …

Functional And Structural Characterization Of The Mevalonate Diphosphate Decarboxylase And The Isopentenyl Diphosphate Isomerase From Enterococcus Faecalis, Chun-Liang Chen

Open Access Dissertations

Enterococcus faecalis causes a diverse range of nosocomial infections (in wounds, the gastrointestinal tract, the blood stream and the endocardium), and multidrug-resistant strains have become a serious issue across countries. Vancomycin, a FDA-approved drug for the disruption of the bacterial cell wall biosynthesis, has been utilized to treat infectious diseases caused by Enterococci; however, the prevalence of vancomycin-resistant enterococci (VRE) threatens communities all over the world. We aim at developing novel therapeutic strategies to control bacterial growth of Enterococci, and we focus on targeting two essential enzymes involved in poly-isoprenoid biosynthesis in Enterococcus faecalis; one is the mevalonate diphosphate decarboxylase …

The Role Of African Leafy Vegetables In Food Security, Marcia M. Croft

Open Access Dissertations

African leafy vegetables (ALVs) are a diverse set of crops grown across sub-Saharan Africa. They have been a staple of traditional diets and contain many critical micronutrients but their importance has been largely ignored by researchers and policymakers at the expense of imported crops. Availability, accessibility, and utilization of ALVs are limited by factors across the supply chain. This research investigated seed systems, drought tolerance, hydroponic production, market barriers, consumer preference, and the impact of gender as related to ALVs. We found that ALVs play an important role in food security and that critical differences exist between formal and informal …

Nanoparticle Toxicity And Molecular Mechanisms In Fish: A Case Study With Silver Nanoparticles, Jiejun Gao

Open Access Dissertations

Nanoparticles (NPs) are widely used in a myriad of commercial and industrial products making their entry to the environment a likely event. NPs have unique physical-chemical properties that result from their small size and high surface area to volume ratio, making them highly reactive and potentially toxic. In Chapter 1, we summarize the effects and mechanisms of metal-based NPs on the vascular system. In vitro studies have shown that NPs are anti-angiogenic because they cause inflammation, oxidative stress, and apoptosis of endothelial cells resulting in increased permeability and decreased proliferation and migration. Whole animal studies examining the effects of NPs …

Syk Promotes Tgf-Beta-Induced P-Body Clearance In Breast Cancer Cells Through The Enhancement Of Autophagy, Shana D. Hardy

Open Access Dissertations

SYK is a protein tyrosine kinase that plays an essential role in the development and activation of immune cells. Its expression, however, is not limited to immune cells. SYK is expressed in a variety of epithelial cell types and epithelial-derived tumors. Reports regarding the role of SYK expression in these diverse cell types and tumors have been opposing. In breast cancer, SYK expression has been overwhelmingly associated with tumor suppression. The loss of Syk expression is observed in invasive breast carcinoma tissue and cell lines and the reintroduction of Syk into metastatic breast cancer cells suppresses tumor growth and metastasis. …

Functional Diversity Enhances Detection Of Ecosystem Stability And Resolution Of Predator-Prey Interactions Within A Multitrophic Community, Ashley Lorraine Kissick

Open Access Dissertations

Habitat fragmentation and loss are principal factors that contribute to the decline of biodiversity which in turn has a negative impact on ecosystem function. There has been growing interest in understanding diversity’s role in the mechanisms behind ecosystem resilience with much attention focusing on how functional diversity, or the range of species’ ecological roles in a community, impacts ecosystem function. Under the functional insurance hypothesis, stability in ecosystems is maintained by species that perform similar functions but have asynchronous responses to disturbance. There are three proposed stability mechanisms that operate through species’ asynchronous responses: cross-scale resilience, response diversity, and density …

A Framework For The Statistical Analysis Of Mass Spectrometry Imaging Experiments, Kyle Bemis

Open Access Dissertations

Mass spectrometry (MS) imaging is a powerful investigation technique for a wide range of biological applications such as molecular histology of tissue, whole body sections, and bacterial films , and biomedical applications such as cancer diagnosis. MS imaging visualizes the spatial distribution of molecular ions in a sample by repeatedly collecting mass spectra across its surface, resulting in complex, high-dimensional imaging datasets. Two of the primary goals of statistical analysis of MS imaging experiments are classification (for supervised experiments), i.e. assigning pixels to pre-defined classes based on their spectral profiles, and segmentation (for unsupervised experiments), i.e. assigning pixels to newly …

Quantifying Terrestrial Ecosystem Carbon Dynamics With Mechanistically-Based Biogeochemistry Models And In Situ And Remotely Sensed Data, Shaoqing Liu

Open Access Dissertations

Terrestrial ecosystem plays a critical role in the global carbon cycle and climate system. Therefore, it is important to accurately quantify the carbon dynamics of terrestrial ecosystem under future climatic change condition. This dissertation evaluates the regional carbon dynamics by using upscaling approach, mechanistically-based biogeochemistry models and in situ and remotely sensed data.

The upscaling studies based on FLUXNET network has provided us the spatial and temporal pattern of the carbon fluxes but it fails to consider the atmospheric CO2 effect given its important physiological role in carbon assimilation. In the second chapter, we consider the effect of atmospheric CO2 …

Ros Regulation Of Axonal Mitochondrial Transport, Pin-Chao Liao

Open Access Dissertations

Mitochondria perform critical functions including aerobic ATP production and calcium (Ca2+) homeostasis, but are also a major source of reactive oxygen species (ROS) production. To maintain cellular function and survival in neurons, mitochondria are transported along axons, and accumulate in regions with high demand for their functions. Oxidative stress and abnormal mitochondrial axonal transport are associated with neurodegenerative disorders. However, we know little about the connection between these two. Using primaryDrosophila neuronal cell culture and the third instar larval nervous system as in vitro and in vivo models, respectively, we studied mitochondrial transport under oxidative stress conditions. In vitro …

Annual Forage Cropping-Systems For Midwestern Ruminant Livestock Production, John Ernest Mcmillan

Open Access Dissertations

Annual forage cropping systems are a vital aspect of livestock forage production. One area where this production system can be enhanced is the integration of novel annual forages into conventional cropping systems. Two separate projects were conducted to investigate alternative forage options in annual forage production. In the first discussed research trial, two sets of crops were sown following soft red winter wheat (Triticum aestivum L.) grain harvest, at two nitrogen application rates 56 and 112 kg ha-1 . The first set of crops were C4 summer annuals seeded within two weeks of wheat grain harvest and included, brown …

Managing Bacterial Wilt, Caused By Erwinia Tracheiphila, On Muskmelon With Early Control Of Striped Cucumber Beetle ( Acalymma Vittatum (F)), And Through Varietal Selection, Ahmad Shah Mohammadi

Open Access Dissertations

Muskmelon (Cucumis melo L), is an important vegetable crop in the United States. It is grown throughout the US, and Indiana ranked 4th in production after California, Arizona and Georgia with 12.4 thousand metric tons and market value of $7.6 million in 2015. Bacterial wilt of cucurbits, which is caused by Erwinia tracheiphila (E. F. Smith), and vectored by striped cucumber beetle (Acalymma vittatum (F)), is one of the most serious diseases of muskmelon that influences muskmelon quality and yield. Many cultivars of muskmelon are grown around the United States, especially in the Midwest. Muskmelon cultivars differ in …

Investigating The Effects Of Ph On Alphaviral E3-E2 Glycoprotein Association, Organization, And Cellular Tropism, Jason Michael Sequra

Open Access Dissertations

In alphaviruses the role of E3 is required in protecting the fusion peptide region of E1 during intracellular transport. Throughout viral processing, the association of E2 and E3 is required for the successful trafficking and incorporation of E1 into the mature virion. This E3-E2 association has been observed to extend to mature virions in the solved structure for the envelope of Semliki Forest virus (SFV) and supported by the solved structure for the entire Venezuelan equine encephalitis virion (VEEV) with exclusive contacts being made between E3-E2. Immunization with monoclonal antibodies against VEEV E3 provided protection for mice challenged by lethal …

Characterizing The Effects Of Repetitive Head Trauma In Female Soccer Athletes For Prevention Of Mild Traumatic Brain Injury, Diana Otero Svaldi

Open Access Dissertations

As participation in women’s soccer continues to grow and the longevity of female athletes’ careers continues to increase, prevention of mTBI in women’s soccer has become a major concern for female athletes as the long-term risks associated with a history of mTBI are well documented. Among women’s sports, soccer exhibits the highest concussion rates, on par with those of men’s football at the collegiate level. Head impact monitoring technology has revealed that “concussive hits” occurring directly before symptomatic injury are not predictive of mTBI, suggesting that the cumulative effect of repetitive head impacts experienced by collision sport athletes should be …

Improving And Elucidating Factors Regulating Black Walnut (Juglans Nigra L.) Clonal Propagation, Micah E. Stevens

Open Access Dissertations

Black walnut (Juglans nigra L.) is a fine hardwood tree species native to the central hardwood region of the United States. High-quality black walnut timber is highly desirable. Traded in both regional and global markets, it has been used for veneer, and the manufacture of high-end products such as cabinets, furniture, and gunstocks. As a result of its high economic value, black walnut has been commercially cultivated for many years, and breeding programs have generated superior timber genotypes with improved marketable traits. Once elite genotypes were developed, it was quickly recognized that black walnut was recalcitrant to clonal propagation …

The Role Of Seed Attributes In Eastern Gray Squirrel Foraging, Mekala Sundaram

Open Access Dissertations

Seed attributes are important predictors of rodent foraging behaviors. I examined the role of seed attributes in eastern gray squirrel (Sciurus carolinensis) foraging behavior from an evolutionary, economic, ecological and biochemical perspective. From an evolutionary perspective (chapter 2), I found that squirrel foraging behaviors are influenced by a combination of phylogenetically conserved and evolutionarily labile seed traits, which supports a diffuse coevolutionary relationship between hardwood trees and squirrels and provides indirect evidence supporting the Janzen-Connell and handling time hypotheses. From an economic perspective (chapter 3), I found that eastern gray squirrels are homogenous with respect to their preferences for seed …

The Relationship Between Protein And Phosphorus Digestion And Retention In Growing Pigs And Broiler Chickens, Pengcheng Xue

Open Access Dissertations

Xue, Pengcheng. Ph.D., Purdue University, December 2016. The Relationship between Protein and Phosphorus Digestion and Retention in Growing Pigs and Broiler Chickens. Major Professor: Dr. Layi Adeola. The objective of this study was to investigate the relationship between protein and P digestion and retention in growing pigs and broiler chickens. The methodology of determining the digestibility of AA and P and the effect of dietary N and P on the digestion and retention of these two nutrients were investigated.

An experiment was conducted in growing pigs to investigate the additivity of AID or SID of CP and AA in mixed …

The Effects Of Dietary Probiotic Inclusion On Skeletal Health Of Poultry And Its Possible Mechanisms, Feifei Yan

Open Access Dissertations

Probiotics are live microorganisms which may confer health benefits on the host when administered in appropriate amounts. Numerous studies have shown that probiotics improve bone health in humans and rodents with less information available on the skeletal health of avians given probiotics. The objective of this study was to determine the effects of probiotic supplementation on bone health of egg-laying and meat-type chickens. Dietary supplementation of a multi-species based probiotic reduced the percentage of shell-less eggs beginning at 4 wk following treatment and increased tibial and femoral bone mineral density in egg-laying hens at 7 wk post-treatment. Similarly, bone mineralization …

Synthesis And Performance Of Novel Supramolecular Tools For Single-Particle Cryogenic Electron Microscopy And Drug And Gene Delivery, Kyle J. Wright

Open Access Dissertations

High-resolution biomacromolecular structure elucidation is fundamentally important to structure-based drug design and basic research into complex biochemical processes. Cryo-EM is an emerging alternative to XRD and NMR that is complementary in many ways relative to XRD and NMR. Materials approaches to cryo-EM are anticipated to greatly facilitate the cryo-EM process, allowing progress toward a more high-throughput application of cryo-EM to address challenges in structural biology. ^ Various affinity-based approaches inspired by approaches previously introduced for 2D crystallization were developed for facilitation of cryo-EM. A library of affinity lipopolymer constructs were synthesized consisting of lipopolymers of various PEG molecular weights conjugated …

Complex Glycan Utilization Preferences Of Human Gut Bacteria, Yunus Emre Tuncil

Open Access Dissertations

Complex glycans, making up dietary fiber, have gained significance in recent years as they are the main energy source for the colonic microbiota which are physiologically important for the host health. Understanding glycan utilization strategies of the members of this community is essential to maximize beneficial health outcomes obtained from them. In order to investigate how the members of our gut microbiota utilize glycans and activate their respective polysaccharide utilization loci (PULs), we performed a series of time-course assays in which two model organisms, Bacteroides thetaiotamicron (Bt) and B. ovatus (Bo), were individually grown in a medium containing carbohydrates utilized …

Subsidies, Aquaculture Technology Adoption, And Welfare Impacts In Ghana And Kenya, Akuffo Amankwah

Open Access Dissertations

This dissertation empirically examines subsidies, aquaculture technology adoption, and welfare implications of fish farming households in Ghana and Kenya. It is divided into three separate chapters, each addressing a specific empirical issue related to aquaculture in the countries.

The second chapter of this dissertation applies the lognormal double hurdle model to a cross-section of fish farms to analyze commercial demand for improved feed, and whether the government feed subsidy program influences private demand for the feed. The results indicate that households’ decisions to participate in improved feed market are affected by the quantity of the subsidized feed received. Once the …

A Unique Perspective On The Demand For Livestock Product Attributes, Elizabeth S. Byrd

Open Access Dissertations

Consumers are increasingly concerned about the social and environmental impacts of the foods they purchase. Both choice experiments and best-worst scaling (BWS) methodology have been used to elicit consumer willingness to pay (WTP) for food attributes and the relative importance of food attributes to consumers. The dissertation consists of four essays. Chapter 2 presents a formal law review article exploring the laws associated with wild game harvest, consumption, and inspections. The remaining three essays (Chapters 3-5) each address an extension or application of choice experiment and/or BWS methodology focused on credence attributes of meat products. Two online surveys were used …

Physiological Aspects Of Relative Changes In Nitrogen And Plant Density Stress Tolerances Over A 38-Year Period Of Us Maize Hybrid Introductions, Keru Chen

Open Access Dissertations

Incremental gains in grain yield of maize hybrids over the decades are the consequence of genotype, environment and management interactions. Historically, genetic improvements in newer hybrids have included longer active grain filling periods (achieved by advancing silking and extending functional stay green in maize leaves); stronger source and sink during grain filling; enhanced tolerance to higher density; and canopy architecture changes. Newer hybrids were known to accumulate more dry matter and nitrogen in the post-silking period, but achieving a more comprehensive knowledge of pre-silking and post-silking dynamics required further understanding of dry matter and nitrogen partitioning in individual organs, as …

Essays On Malawian Agriculture: Micro-Level Welfare Impacts Of Agricultural Productivity; Profitability Of Fertilizer Use; And Targeting Of Fertilizer Subsidy Programs, Francis Addeah Darko

Open Access Dissertations

This dissertation comprises of three essays that address different aspects of agriculture in Malawi using a two-wave panel data collected by the National Statistical Office of Malawi with support from the World Bank Living Standards Measurement Study – Integrated Surveys on Agriculture (LSMS-ISA) program. Each essay stands alone as an independent study because of differences in research questions and the methodologies used in addressing the questions.

The first essay analyzes the micro-level welfare impacts of agricultural productivity. Welfare is measured by various dimensions of poverty and food insecurity; and agricultural productivity is measured by maize yield and value of crop …

Gonadal Intersex In Teleosts: Mechanisms, Molecular Biomarkers And Diagnostic Assays, Ahmed M.E. Abdel-Moneim Mohamed

Open Access Dissertations

Natural and synthetic estrogenic and androgenic compounds are continuously released into aquatic ecosystems. Exposure of teleost fishes to these contaminants can negatively impact sex differentiation and reproductive output. Specifically, development of gonadal intersex in gonochoristic (fixed sex) fish species has been studied extensively in relation to exposure to this class of compounds. The main objectives of this dissertation were to: 1) conduct field and laboratory studies to investigate the molecular signaling pathways behind the development of gonadal intersex; and 2) establish molecular biomarkers and assays for testing the ability of environmental pollutants to develop this condition using a battery of …

Bayesian Causal Inference Of Cell Signal Transduction From Proteomics Experiments, Robert D. O. Ness

Open Access Dissertations

Cell signal transduction describes how a cell senses and processes signals from the environment using networks of interacting proteins. In computational systems biology, investigators apply machine learning methods for causal inference to develop causal Bayesian network models of signal transduction from experimental data. Directed edges in the network represent causal regulatory relationships, and the model can be used to predict the effects of interventions to signal transduction. Causal inference approaches applied to proteomics experiments use statistical associations between observed signaling protein concentrations to infer a causal Bayesian network model, but there is no experimental and analysis framework for applying these …

The Biology And Management Of Palmer Amaranth (Amaranthus Palmeri S. Wats) In Indiana, Douglas J. Spaunhorst

Open Access Dissertations

Palmer amaranth is a pernicious summer annual weed that has evolved resistance to six herbicide sites of action in the U.S. and threatens agriculture production. In 2011, Palmer amaranth was identified in flood plains in two southern Indiana counties (Posey and Vanderburgh). Determining if Palmer amaranth can survive and reproduce in northern Indiana may provide insight if this weed will be problematic for northern row crop producers. The objectives of our research were to identify fields containing Palmer amaranth and determine the distribution of herbicide resistance traits in Indiana; determine the influence of tillage frequency and tillage intervals on Palmer …

Dynamic Regulation Of Dna Demethylation And Rna-Directed Dna Methylation In Arabidopsis, Kai Tang

Open Access Dissertations

DNA methylation is an important epigenetic mark present in many eukaryotes, and is involved in many crucial biological processes, such as gene imprinting, regulation of gene expression, and genome stability. Proper genomic DNA methylation patterns are achieved through the concerted action of DNA methylation and demethylation pathways. In the model plant species Arabidopsis thaliana, ROS1 (REPRESSOR OF SILENCING 1) is one of the DNA demethylases and the key component in the demethylation pathway. Dysfunction of ROS1 leads to increase in DNA methylation level at thousands of genomic loci. However, the features of ROS1 targets are not well understood. In the …

Repurposing Non-Antimicrobial Drugs To Treat Multi-Drug Resistant Bacterial And Fungal Infections, Shankar Thangamani

Open Access Dissertations

Bacterial and fungal resistance to conventional antimicrobials is a burgeoning global health epidemic that necessitates urgent action. Even more alarming, the development of new antimicrobials to treat these multidrug-resistant pathogens has not kept pace with the rapid emergence of resistance to current antimicrobials. Antimicrobial drug development through the traditional de novo process is a risky venture given the significant financial and time investment required by researchers and limited success rate of translating these compounds to the clinical setting. This has led researchers to mine existing libraries of clinical molecules in order to repurpose old drugs for new applications (as antimicrobials). …