Life Sciences Commons^™

Effects Of Prescribed Fire Regimes On White-Tailed Deer (Odocoileus Virginianus) Browse, Forage, And Nutrient Availability In The Pineywoods Ecoregion Of Texas, Wyatt L. Bagwell

Electronic Theses and Dissertations

Fire is a management tool for white-tailed deer (Odocoileus virginianus) habitat, influencing browse availability, herbaceous production, and nutrient content. In 2020 and 2021, this study utilized 46 plots across East Texas to assess these habitat components. A stem count index survey method was used to assess browse utilization prior to April in both years, and preferred browse species were clipped and analyzed for nutrient availability, and herbaceous production was also measured. Additionally, white-tailed deer population data, browse survey data, and recent fire history were obtained from five different wildlife management areas to examine their relationship. Deer had preferences …

Optimization Of Clostridium Septicum Antigen Production And Evaluation Of Vaccine Administration Parameters For A Candidate Bacterin-Toxoid To Prevent Dermatitis In Commercial Turkeys, Aaron Forga

Graduate Theses and Dissertations

The objective of this thesis was to optimize the hemolytic activity of two isolates of Clostridium septicum to evaluate if hemolytic titer of C. septicum antigen at time of formalin inactivation corresponded to increased serum antibody titer to the C. septicum alpha-toxin of turkeys immunized with an experimental formalin inactivated bacterin-toxoid vaccine. Chapter 1 provides a brief overview of the thesis. Chapter 2 consists of a literature review focused on clostridial dermatitis, specifically C. septicum-associated dermatitis (cellulitis) that affects commercial turkeys. Chapter 3 outlines our attempts to optimize an experimental autogenous bacterin-toxoid vaccine as a potential strategy to mitigate clostridial …

Differential Impacts Of Hhv-6a Versus Hhv-6b Infection In Differentiated Human Neural Stem Cells, Elham Bahramian

Graduate Theses and Dissertations

Within the family Herpesviridae, sub-family β-herpesvirinae, and genus Roseolovirus, there areonly three human herpesviruses that have been described: HHV-6A, HHV-6B, and HHV-7. Initially, HHV-6A and HHV-6B were considered as two variants of the same virus (i.e., HHV6). Despite high overall genetic sequence identity (~90%), HHV-6A and HHV-6B are now recognized as two distinct viruses. Sequence divergence (e.g., >30%) in key coding regions and significant differences in physiological and biochemical profiles (e.g., use of different receptors for viral entry) underscores the conclusion that HHV-6A and HHV-6B are distinct viruses of the β-herpesvirinae. Despite these viruses being implicated as causative agents in …

Micronutrient Concentration Effects On Lettuce Growth And Susceptibility To Pythium, Kalyn M. Helms

Graduate Theses and Dissertations

In hydroponic production waterborne pathogens such as Pythium are ubiquitous and continually threaten a wide range of Controlled Environment Agriculture (CEA) crops in hydroponic production, including but not limited to: lettuce, spinach, basil, arugula, cucumber, tomato, sweet pepper, roses, chrysanthemums, and cannabis (Sutton et al., 2006; Gull, 2002; McGehee and Raudales, 2021; Gillespie, 2020). Despite extensive sanitation measures, disease control in hydroponics is fallible and requires constant surveillance and management to minimize outbreaks (Sutton et al., 2006). A potential disease suppression strategy is to increase micronutrient concentrations within hydroponic systems to naturally strengthen plant defenses against pathogens such as Pythium. …

Thermal Inactivation Kinetics Of Salmonella In Milk Powder As Impacted By Water Activity And Powder Type, Erika Litta Kadas

Graduate Theses and Dissertations

Historically, low-water activity (aw) foods (aw <0.65) were considered to be microbiologically safe for consumption. However, these foods have been implicated in outbreaks of pathogens such as Salmonella enterica, at a frequency that surely challenges this assumption of safety. Although usually implicated in outbreaks involving poultry and egg products, Salmonella spp. have frequently been the culprit in several outbreaks and recalls associated with low-water activity foods (LWAF) due to contamination resulting from the environment, animals, or even the employees during pre-or post-processing. One such LWAF that has been associated with Salmonella spp. outbreaks is milk powder. Milk powders are used in a variety of products ranging from infant formula to confectionary goods. With their widespread use, improving their safety is imperative. A key step in improving their safety is to thoroughly investigate preventive controls related to milk powder processing. The Food Safety Modernization Act (FSMA) established the Preventive Controls for Human Foods Rule, which mandates that processors design and establish a food safety plan outlining any potential hazards and the steps they will take to ensure those hazards do not compromise the safety of the product. Presently, the dairy industry does not have an established kill-step for milk powders post-spray drying. Spray drying may reduce some microbial populations, however, desiccation(e.g., spray drying) is not considered a kill-step. The work outlined in this thesis aims to assist our dairy industry partners in establishing their own thermal process for milk powders post-spray drying. Moisture sorption isotherms of two milk powders (nonfat dry milk: NFDM and a milk protein concentrate with 85% protein content: MPC-85) were determined and showcased that the temperatures at which the isotherms were determined (23, 40, or 60°C) significantly affected both the adsorption and desorption isotherms (p<0.0001) for each powder. Secondly, the thermal inactivation kinetics of Salmonella spp. in both powders were evaluated at two different water activities (0.20 and 0.30) and three temperatures (75, 80, and 85°C) to determine the effect of water activity on the thermal resistance of a cocktail of Salmonella spp. The D-values of Salmonella were heavily influenced by the thermal treatment temperature (p< 0.0001), but not the water activity (p >0.05). The overall findings contained within this thesis provide valuable information about the thermal inactivation kinetics of Salmonella spp. to our partners in the dairy industry so that they may implement an appropriate thermal process for their milk powders.

Using Molecular Dynamics Simulations To Decipher Mechanistic Details Of Biomolecular Processes Of Biology And Biotechnology Oriented Applications, Adithya Polasa

Graduate Theses and Dissertations

Researchers in chemistry and biology often utilize computer simulations, in conjunction with experimental data, to model and predict the structures, energies, kinetics, processes, and functions of the systems that are their focus of study, ranging from single molecules to whole viruses. Here, we use molecular dynamics (MD) techniques to gain a deeper understanding of biomolecular processes in biology and biotechnology-oriented applications. Using a mixture of equilibrium and non-equilibrium MD simulations, this work describes the insertion process of YidC at the atomic level. In order to better comprehend the insertion process, several docking models of YidC-Pf3 in the lipid bilayer were …

Molecular Mechanisms Underlying Aberrant Circulating Steroid Hormones In Gnrhr-Ii Knockdown Boars And Their Control Littermates, Dorothy H. Elsken

Department of Animal Science: Dissertations, Theses, and Student Research

Swine are the only livestock species that produce a functional protein for both GnRH-II and its receptor (GnRHR-II). Our laboratory reported that the interaction between GnRH-II and GnRHR-II facilitates testosterone production, independent of LH stimulation. To further examine GnRHR-II function, we developed a swine line with 70% reduced GnRHR-II mRNA levels (GnRHR-II KD) compared to control littermates. Mass spectrometry analysis of serum revealed that circulating levels of gonadal steroids were reduced in mature transgenic vs. control boars. Paradoxically, evaluation of testicular tissue indicated no difference between lines for gonadal steroid hormone levels. To address a potential cause for this discrepancy, …

The Invisible Meat Microcosmos: Investigations Of Processed Meats' Specific Spoilage Organisms, Rebecca Furbeck

Department of Animal Science: Dissertations, Theses, and Student Research

As humankind grows in population, so will our need to compete against bacterial populations which spoil foodstuffs before we are able to consume them. This dissertation aims to identify the bacterial communities responsible for meat spoilage, and the mechanisms that govern the behaviors of these organisms. The literature review summarizes the state of knowledge regarding factors that influence meat microbiome composition, and how analytical methods can influence research outcomes. Study 1 aimed to identify the impact of additional ingredients and processing steps on the microbial ecology of processed turkey products. The main specific spoilage organisms (SSOs) belonged to the orders …

Impacts Of Feeding Biochar To Beef Cattle On Greenhouse Gas Emissions And Performance And Characterizing Yearling Steers Grazing Smooth Bromegrass Pasture Using Gps, Holly A. Heil

Department of Animal Science: Dissertations, Theses, and Student Research

As global warming continues to rise, the pressure and growing demand for sustainable animal production is increasing. Livestock naturally produce greenhouse gas emissions through enteric fermentation. Dietary manipulation strategies have been sought out to decrease emissions in ruminants using feed additives.

Two independent finishing feedlot experiments evaluated two types of biochar and its effects on animal performance, carcass characteristics and greenhouse gas emissions. Experiment 1 utilized pistachio shell biochar and experiment 2 utilized biochar sourced from ponderosa pine wood waste, both types included at 1% of the diet DM. The addition of biochar to the diet did not impact animal …

The Nebraska 4-H Equine Advancement Level Program’S Role In Positive Youth Development Using The Five Cs Model: An Exploratory Study, Eunhye Mccarthy

Department of Animal Science: Dissertations, Theses, and Student Research

Positive youth development (PYD) focuses on developing the strengths of youth through positive activities and behaviors rather than reducing negative tendencies. A well-researched model of PYD is the five C’s model that is popularly used in youth development organizations such as 4-H. The Nebraska 4-H Equine Advancement Level program was intended to serve as a guidebook for instruction and assessment of youth as they learn more about horses and horsemanship skills. Each of the four levels has an emphasis in developing a 4-H member’s responsibility, self-discipline, self-reliance, patience, and pride of accomplishments. The program was started approximately 30 years ago …

Variance Component Estimates For Growth Traits In Beef Cattle Using Selected Variants From Imputed Low-Pass Sequence Data, Chad A. Russell

Department of Animal Science: Dissertations, Theses, and Student Research

A beef cattle population (n = 2,343) was used to assess the impact of variants identified from imputed low-pass sequence (LPS) on the estimation of variance components and genetic parameters of birth weight (BWT) and post weaning gain (PWG). Variants were selected based on functional impact and were partitioned into four groups (Low, Modifier, Moderate, High) based on predicted functional consequences and re-partitioned based on consequence of mutation, such as missense and untranslated region variants, into six groups (G1-G6). Each subset was used to construct a genomic relationship matrix (GRM) for univariate animal models. Multiple analyses were conducted to …

Evaluation Of Nutritional Factors Affecting Sow Reproductive Longevity, J'Nan E. Wittler

Department of Animal Science: Dissertations, Theses, and Student Research

Sow reproductive longevity is an important trait for swine operations from a production and economic standpoint. Previous research has shown that a sow needs to produce 3 litters before she covers the costs associated with introducing her to the operation. A literature review of research conducted related to sow longevity is discussed in Chapter 1. Chapters 2 and 3 present data from the University of Nebraska – Lincoln’s long-term sow longevity research. The research looks at the effects of energy restriction with soy hulls during gilt development on sow reproductive longevity through 4 parities. Chapter 2 presents data from replications …

Students' Perceptions Of Online Equine Courses And Their Impacts On Learning Outcomes, Blaire L. (Gibbens) Speck

Department of Animal Science: Dissertations, Theses, and Student Research

Post-secondary education is always changing and evolving. Over the last few years, significant changes in education have resulted in an increased number of online courses. Approximately 28% of students seeking higher education participate in at least one online course and 14% are enrolled exclusively in distance or online programs (Allen & Seaman, 2016). However, courses that are typically hands-on, like equine science, may be more challenging online. The hands-on experiences in equine science classes help prepare students for future careers. Due to an increase in students choosing to take courses online, a review of online teaching methods was conducted to …

Inventory Reveals Wide Biodiversity Of Edible Insects In The Eastern Democratic Republic Of Congo, Jackson Ishara, Rodrigue Ayagirwe, Katcho Karume, Gustave N. Mushagalusa, David Bugeme, Saliou Niassy, Patchimaporn Udomkun, John Kinyuru

All Peer-Reviewed Publications

In response to growing food demand, edible insects are perceived as an opportunity to alleviate food insecurity. With its wide edible insects’ biodiversity, the Democratic Republic of Congo is one of Africa’s most critical entomophagous. This study aimed at giving a first insight on inventory showing diversity, perception, consumption, availability, host plants, harvesting techniques and processing techniques of edible insects in South-Kivu, DRC. It recorded twenty-three edible insects belonging to nine families and five orders, some of which are consumed in the larval, adult, egg and pupa stages. Rhyncophorus phoenicis, Alphitobius diaperinus, Macrotermes subhyalinus and Acheta domesticus were the most …

Potential Distribution Of Fall Armyworm In Africa And Beyond, Considering Climate Change And Irrigation Patterns, Bipana Paudel Timilsena, Saliou Niassy, Emily Kimathi, Elfatih M. Abdel-Rahman, Irmgard Seidl-Adams, Mark Wamalwa, Henri E.Z. Tonnang, Sunday Ekesi, David P. Hughes, Edwin G. Rajotte, Sevgan Subramanian

All Peer-Reviewed Publications

The fall armyworm, Spodoptera frugiperda (FAW), first invaded Africa in 2016 and has since become established in many areas across the continent where it poses a serious threat to food and nutrition security. We re-parameterized the existing CLIMEX model to assess the FAW global invasion threat, emphasizing the risk of transient and permanent population establishment in Africa under current and projected future climates, considering irrigation patterns. FAW can establish itself in almost all countries in eastern and central Africa and a large part of western Africa under the current climate. Climatic barriers, such as heat and dry stresses, may limit …

Cross-Modal Associations Between Hand-Feel Touch And Oral Irritation, Ragita Cantika Pramudya

Graduate Theses and Dissertations

Hand-feel touch cues have been shown to influence the perception of other sensory modalities and can be used as means to create expectations toward food or beverage products presented concurrently with such cues. However, to date, there has been limited research on how these hand-feel touch cues could impact oral irritation elicited by capsaicin-containing products. Because oral irritation sensation is a dynamic perception lasting a period of time, temporal methodologies, such as Time-Intensity (TI) and Temporal-Check-All-That-Apply (TCATA), must be used when evaluating capsaicin-containing products. The use of temporal methodologies when examining the cross-modal effects of other cues on capsaicin irritation …

Enhancing Amino Acid Utilization For Broiler Chickens Under Different Scenarios Of Dietary Protein Reduction And Subclinical Coccidiosis, Derrell Trevor Lee

Graduate Theses and Dissertations

Five experiments were conducted to evaluate responses of broiler chickens fed diets with different dietary amino acid (AA) levels when fed normal and reduced dietary crude protein (RCP) diets and reared under different coccidiosis control programs. In the studies with the use of RCP diets, the relationship between dietary Gly + Ser and the Met:Cys ratio was investigated. Experiment 1 evaluated broilers in 2 coccidiosis control programs (live vaccine or in-feed zoalene) and fed increased dietary AA derived from soybean meal or unbound sources from 0-40 d. Vaccination impaired young (0-26 d) broiler body weight gain (BWG) and feed conversion …

Death Of A Bacterium: Exploring The Inhibition Of Staphylococcus Aureus By Burkholderia Cenocepacia., Tiffany Brandt

Electronic Theses and Dissertations

Antimicrobial resistance is a phenomenon of increasing concern as antimicrobial overuse and misuse eliminate current therapeutic options, ushering society into a post-antimicrobial era. Antibiotic discovery and synthesis efforts are urgently needed to counter the increasing burden of antimicrobial resistance. Staphylococcus aureus is a causative agent of a variety of clinical manifestations including bacteremia, endocarditis, soft tissue infection, osteomyelitis, and device-related infections. S. aureus infection presents additional treatment challenges due to its capacity for biofilm formation, which is a mode of growth that confers protection from antibiotics and physical elimination, and the emergence of antibiotic resistant strains, including methicillin-resistant S. aureus …

Bayesian Methods For Graphical Models With Neighborhood Selection., Sagnik Bhadury

Electronic Theses and Dissertations

Graphical models determine associations between variables through the notion of conditional independence. Gaussian graphical models are a widely used class of such models, where the relationships are formalized by non-null entries of the precision matrix. However, in high-dimensional cases, covariance estimates are typically unstable. Moreover, it is natural to expect only a few significant associations to be present in many realistic applications. This necessitates the injection of sparsity techniques into the estimation method. Classical frequentist methods, like GLASSO, use penalization techniques for this purpose. Fully Bayesian methods, on the contrary, are slow because they require iteratively sampling over a quadratic …

Re-Engineering Cardio-Oncology Testing Using Biomimetic Heart Slice Cultures., Jessica Miller

Electronic Theses and Dissertations

28% of drug withdrawal from the market are due to unforeseen disruptions in cardiomyocyte contractility and electrophysiology. The most commonly used platforms for drug testing are in vivo animal models and in vitro cell culture models. While both have been of paramount importance for the discovery and detection of many cardiotoxicities and mechanisms of action, they lack the ability to model an intact human myocardium. This work aims to establish cardiac tissue slices, which are 300-micron thin tissue sections taken from the left ventricular myocardium, as an alternative platform for cardio-oncology studies, specifically cardiotoxicity testing. Additionally, this work aims to …

Conflictos Entre Humanos Y Fauna Silvestre En Una Zona De Amortiguamiento De San Ramón, Costa Rica, Rebeca Solano-Gómez, José Manuel Mora

Biology Faculty Publications and Presentations

“Human-wildlife conflict in a buffer zone in San Ramón, Costa Rica”. Introduction: Currently, biodiversity is mainly managed by protected areas, but proximity with human activities results in conflicts, which are poorly studied in the tropics. Objective: To estimate human-wildlife conflict in the buffer zone of the Alberto Manuel Brenes Biological Reserve, San Ramón, Costa Rica. Methods: We interviewed the owners or managers of 59 farms. Results: We recorded 540 incidents, mostly with mammals (N=479); coyotes (Canis latrans) killed 1 074 animals in 183 attacks at 12 farms. We also recorded conflicts with jaguar, Panthera onca, puma, Puma concolor, ocelot, Leopardus …

In-Field And Greenhouse Assessments Of A Selection Of Preemergent Herbicides On Newly Planted Blackberries, Kayla Knepp

Graduate Theses and Dissertations

This field trial assesses some of the preemergence herbicide options available to growers and their effect on newly transplanted blackberries (Rubus L. subgenus Rubus Watson). Weed control has recently been surveyed as a top priority for blackberry growers; however, limited preemergence herbicides are registered for new blackberry plantings. Weed control is an ongoing component of blackberry production and with few in-season postemergence herbicide options available, growers rely on preemergence herbicides to maintain clean fields. The preemergent herbicides assessed in this trial were chosen with the intention to broaden the chemical control options available to growers in new plantings. A two-year …

The Role Of Microbiota-Biotransformed Bile Acid Metabolites On Campylobacter Jejuni- And Clostridium Perfringens-Infection, Ying Fu

Graduate Theses and Dissertations

Campylobacter jejuni (C. jejuni) and Clostridium perfringens (C. perfringens) are two leading pathogenic bacteria responsible for both human and animal diseases. In chapters Ⅱ to Ⅳ, I presented an overview of current knowledge on the role of immune response, microbiota, bile acids and their microbial metabolites on campylobacteriosis, and C. perfringens induced necrotic diseases.In chapter Ⅴ, I investigated effects of deoxycholic acid-modulated anaerobes (DCA-Anaero) on attenuating chicken transmission-exacerbated campylobacteriosis. SPF Il10-/- mice were gavaged with clindamycin for 7 days followed by infected with three C. jejuni strains, Cj-P0 (C. jejuni AR101), Cj-P1 (from chicken pre-infected with C. jejuni AR101), and …

Amino Acid Nutrition In Broiler Breeders, Jordan Weil

Graduate Theses and Dissertations

Amino acids (AA) are commonly referred to as the building blocks of protein due to their role in the synthesis of proteins. Considering these nutrients are involved in growth and metabolism, much emphasis is placed on determining the dietary requirements of amino acids. Therefore, an experiment was conducted to evaluate the amino acid requirements of performance parameters such as egg weights, egg production, egg mass, feed conversion ratios, and body weight gain in two age groups of broiler breeders. In this experiment, 648 Cobb 700 broiler breeder hens were placed in individual cages to determine the amino acid requirements of …

A Study On Interactions Between Metal-Organic Frameworks And Biological Materials, Josh Phipps

Graduate Theses and Dissertations

Metal-organic frameworks or MOFs are an extremely useful tool in many areas of applications. Their popularity in recent years has arisen from their high efficiency in catalytic chemical reactions. This is made possible due to their porous interior and the ability of the MOFs components to be functionalized. These same traits make MOFs excellent for use in protein encapsulation or immobilization and have the potential to become excellent drug carriers. Their development in this utilization has been limited dramatically compared to MOFs chemical applications. This is due in part to the nature of biological processes taking longer to study, but …

Molecular Characterization Of Nitrogenase Regulation In Methanosarcina Acetivorans, Melissa Chanderban

Graduate Theses and Dissertations

Nitrogenase is the metalloenzyme only found in bacteria and archaea that is essential for biological nitrogen fixation (diazotrophy), but it can also serve as a catalyst in biofuel production. All diazotrophs contain a molybdenum (Mo) nitrogenase, while some species contain additional alternative nitrogenases where either vanadium (V) or iron (Fe) replace Mo in the active site cofactor. Nitrogen fixation by bacteria has been extensively studied. The limited investigation of nitrogen fixation in methanogenic archaea (methanogens) indicates production of nitrogenase is simpler than in bacteria and methanogen nitrogenase has different biochemical properties. Thus, methanogen nitrogenases provide a promising alternative for genetic …

Hypothesis Testing And Parameter Estimation In Mixture Cure Models For Cancer Survival Data, Mohammod Mahmudur Rahman

Graduate Theses and Dissertations

In oncology clinical trials, when a treatment is administered to the patient population, a certain subset of patients may respond to the treatment while the other does not. The positive responders with long-term survival are considered “statistically cured” and can be referred to as cured patients or long-term survivors. When a proportion of patients achieve long-term survival, the hazard functions of two arms (control vs. treatment) are no longer proportional. As a result, the traditional log-rank test, which is the most popular test to evaluate the effectiveness of a treatment in clinical trials, tends to lose its power. In this …

Identification Of Possible Vectors For Histomoniasis In Turkeys On Commercial Farms In Arkansas And Oklahoma, Treva Dillon

Graduate Theses and Dissertations

Histomonas meleagridis, is a parasitic protozoan, commonly found in the gallinaceous species of birds and is the causative agent of Blackhead disease. The cecal worm, known as Heteraskis gallinarum, acts as a vector in the spread of H. meleagridis in gallinaceous birds. H. meleagridis develops inside the cecal worm and in its eggs which allows H. meleagridis a method to survive in the environment. Blackhead disease causes high mortality rates in both chickens and turkeys; however, turkeys are noted to have a higher mortality rate compared to chickens. Molecular diagnostic testing such as PCR has been developed by creating primers …

Comparative Analysis Of Conformational Transition Pathways In Homologous Proteins, Dylan Sebastien Ogden

Graduate Theses and Dissertations

Molecular dynamics (MD) simulations are routinely used to study the dynamics of proteins. However, conventional MD limited to the sampling of local conformational changes as the functionally important conformational transitions of proteins often extend beyond the timescales of the simulations employed, for example, membrane transport proteins. We have determined the combination of multiple MD based techniques that allows for a rigorous characterization of energetics and kinetics of large-scale conformational changes in membrane proteins. The methodology is based on biased, nonequilibrium collective variable based simulations including nonequilibrium pulling, string method with swarms of trajectories, bias-exchange umbrella sampling, and rate estimation techniques. …

Urbanization Of Aedes Mosquito Populations And Evolution Of Arboviral Disease Risk In Africa, Sheila B. Agha, David P. Tchouassi

All Peer-Reviewed Publications

The arboviral diseases dengue, chikungunya, and yellow fever are re-merging and gaining a foothold in Africa, with a significant threat of large outbreaks in urban areas. Although their emergence is intimately linked to the primary vector Aedes aegypti, which thrives in urban environments, the risk of these diseases remains substantially heterogeneous in different geographic areas. Range expansion of invasive mosquito species Aedes albopictus, and colonization of urban habitats by sylvatic and peridomestic Aedes vectors, are likely to alter the diseases’ epidemiology. We discuss how a network of different vector species and perhaps vector subpopulations could interact with associated serotypes/genotypes/lineages of …