Life Sciences Commons^™

A Comparative Study Of Medicago Truncatula Transcriptomes As They Relate To Saponin Defenses Against Insect Pests, Audra Mae Rogers

Graduate Theses and Dissertations

Triterpene saponins are a class of defensive plant-derived compounds, which have a

variety of functions including antimicrobial, insecticidal, and nematicidal activities. This

research assessed the performance of the beet armyworm, Spodoptera exigua, following ad

libero feeding on Medicago truncatula accessions differing in specialized metabolite and

saponin profiles. Insect performance did not directly relate to the foliar saponin levels in the

accessions, which was measured using HPLC mass spectrometry. Accession ESP105 had the lowest foliar saponins overall, yet had similar levels of soyasaponins compared to the other accessions. Conversely, accessions A17, PRT178, and GRC43 had high foliar saponins with particularly high …

The Effects Of Meloidogyne Incognita And Heterodera Glycines On The Yield And Quality Of Edamame In Arkansas, Juliet Fultz

Graduate Theses and Dissertations

Edamame (Glycine max), also known as vegetable soybean, was introduced to the United States from Japan in 1890 and has been growing in popularity as a nutrient-rich, low-sugar snack in recent years. In 2012, the American Vegetable Soybean and Edamame, Inc. established the first domestic commercial processing plant in Mulberry, Arkansas and contracted local growers for production. Since the crop is harvested when seed are immature, management practices are different from those for traditional soybean. Plant-parasitic nematodes, particularly Meloidogyne incognita (southern root-knot) and Heterodera glycines (soybean cyst), are common in Arkansas and are pests of concern for edamame growers. Edamame …

Rice Blast Disease In The U.S. And Africa: Determination Of Pathogen Diversity And The Identification Of Resistance Genes For Disease Management, Felix Rotich

Graduate Theses and Dissertations

Rice blast caused by Magnaporthe oryzae (= Pyricularia oryzae) B. Couch, is a leading disease of rice. Magnaporthe oryzae exhibits a high degree of diversity. The diversity of isolates of M. oryzae from Africa and the U.S. were examined using vegetative compatibility and virulence phenotyping as well as determination of variation in the avirulence gene AVRPiz-t in isolates from Africa. Also, evaluation of blast resistance genes in the interspecific rice germplasm “New Rice for Africa” NERICA was done using F2 progeny of the cross of U.S. susceptible cultivar M204 and NERICA 12. The U.S. isolates were in three vegetative compatibility …

Investigation Of The Inherent Chemical, Structural, And Mechanical Attributes Of Bio-Engineered Composites Found In Nature: Alligator Gar’S Exoskeleton Fish Scales, Wayne Derald Hodo

Graduate Theses and Dissertations

The U.S. Army has determined a huge cost savings of up to 51% can be accomplished by reducing the gross vehicle weight, for their personnel carrier, by 33%. To cut cost, composite materials are needed. Man-made composites can have superior material properties (high-strength, high-fracture toughness, and lightweight), but they are prone to delamination at the glued-layered interface. In contrast, fish scale is a natural composite that has the same material properties and, additionally, tend not to delaminate.

The focus of this study was to learn how nature integrates hard and soft materials at each length scale to form a layered …

The Role Of G-Protein Signaling In Pathogenesis In Cercospora Zeae-Maydis, Brant Smith

Graduate Theses and Dissertations

Gray leaf spot, caused by Cercospora zeae-maydis, is one of the most destructive foliar diseases of maize worldwide. C. zeae-maydis orients hyphal growth towards stomata (stomatal tropism) and forms infectious structures (appressoria) that are necessary for successful infection. Although some genes involved in pathogenesis in C. zeae-maydis have been identified, the molecular mechanisms are not well understood. In fungi, heterotrimeric G-proteins consist of three subunits (α, β, and γ) and mediate responses to environmental stimuli. They regulate diverse functions, including nutrient detection, virulence, fungal development, conidiation, secondary metabolism, and pathogenesis in many plant pathogenic fungi. This research explored the role …

Storage Of Round And Square Switchgrass Bales: Effect Of Storage Time And Fungal Inoculation On Saccharification Efficiency, Noaa Frederick

Graduate Theses and Dissertations

To produce fermentable sugars from lignocellulosic biomass feedstock, severe pretreatment conditions are needed (either high acid concentration, temperature, or retention times). High severities can produce toxic byproducts which inhibit enzymatic hydrolysis or fermentation. In order to reduce pretreatment severities (and thus increase enzyme and fermentation efficiency), the white-rot fungus Pleurotus ostreastus was seeded into square and round bales of Kanlow switchgrass (Panicum virgastum L.) and left in the field over a period of 9 month. The laccase producing fungus is believed to selectively degrade lignin, a common plant structural polymer, which can function as an enzymatic inhibitor. Samples were taken …

Structural And Functional Studies Of The Papain-Like Protease 2 From Mouse Hepatitis Virus, Yafang Chen

Open Access Dissertations

Our goal is to establish a system to investigate how the deubiquitinating (DUB) and deISGylating activities of coronavirus (CoV) papain-like protease domains (PLPs) are involved in virus immune evasion. To this end, we chose PLP2 from mouse hepatitis virus (MHV) as our target of study because MHV has historically served as a model system for the study of CoVs, and it has undeniable advantage of ease in culturing in comparison to human coronaviruses.

It is reported here the expression and purification of a region of MHV nsp3 that contains the catalytic core of the PLP2 domain and its neighboring domains. …

Validating Side Scan Sonar As A Fish Survey Tool, Michael A. Bollinger

Theses and Dissertations

Hydroacoustic methods can be used to answer a variety of questions regarding fish populations and behavior. In this study, side scan sonar methodology was developed to quantify abundance and biomass and compared to established visual observation methods on SCUBA over artificial reef structures in the western Gulf of Mexico. Side scan sonar methods were equivalent to SCUBA surveys for measuring fish abundance over the same reef areas, however, abundances were significantly higher when the larger area sampled by side scan was utilized. Side scan sonar methods were also more time efficient than SCUBA, ROV and long line fishing methods (66.7%, …

Comparing Reproductive Capacity Of Nearshore And Offshore Red Snapper, Lutjanus Campechanus, On Artificial Reefs In The Western Gulf Of Mexico, Ricky J. Alexander

Theses and Dissertations

Red snapper collected quarterly from four artificial reefs in south Texas were examined to compare total length, total weight, age, and the proportion of male to female red snapper, calculate gonadosomatic index values, batch fecundity, annual spawning frequency, and annual fecundity, and estimate size and age at maturity. Spawning occurred from April to September, with most active spawning observed in June (58%). Despite larger red snapper producing more eggs, and fish being larger offshore, most active spawning (68%) and egg production (74%) was observed nearshore. Female red snapper reached 50% maturity (L50) between 350-550 mm, and L75 by 600 mm. …

Decomposition And Nitrogen Dynamics Of Turtle Grass (Thalassia Testudinum) In A Subtropical Estuarine System, Monica Delgado

Theses and Dissertations

Seagrass beds are pivotal in the functioning of coastal ecosystems in terms of productivity, organic matter turnover and nutrient cycling. Aiming to document decay and nitrogen (N) dynamics of turtle grass (Thalassia testudinum) in a subtropical estuarine system, decomposition patterns of leaves and rhizomes were characterized and compared. Nitrogen usage during decomposition of tissues, and of live tissues and epiphytes growing on live leaves, was also quantified and compared. Stable isotope ratios allowed tracing N within the seagrass bed, following N incorporation into seagrass tissues from the surrounding media (water, sediment). Leaves had a higher N content and decomposed at …

Examination Of The Chagas Disease Vector, Triatoma Gerstackeri, In The Lower Rio Grande Valley, Alfredo Flores

Theses and Dissertations

Chagas disease is caused by the protozoan parasite Trypanosoma cruzi, which is carried by an insect vector of the family Reduviidae, and of the subfamily Triatomina. The species Triatoma gerstaeckeri is identified as the primary vector of T. cruzi within the Rio Grande Valley. Species of Triatoma gerstaeckeri were trapped in La Sal del Rey National Refuge in 2012 and 2013.

Data indicates a seasonal dispersal pattern of activity for T. gerstaeckeri. Optimal time of capture was between 1-2 hours after sunset. Different methods were utilized to determine the best combination of lures. Results indicate that the UV-light alone is …

Activation Of Microglia In The Rotenone Lymnaea Stagnalis Model Of Parkinson's Disease, Xiomara Galvan

Theses and Dissertations

Parkinson’s disease (PD) is the most common irreversible neurodegenerative movement disorder affecting approximately ten million people worldwide. In the central nervous system (CNS), PD is known by the selective loss of Dopamine (DA) cells of the substantia nigra pars compacta. Although the disease has been very widely studied, the underlying mechanisms are not yet understood. Several hypotheses have arisen as result of injury of the mitochondria, some experiments include microglia activation, microtubule damage, and reactive oxidative species, which all result in the death of DA cells. The theory of microglia activation upon inflammation was explored in this study. Using the …

Effects Of Shrub Encroachment And Removal On South Texas Coastal Prairie Flora, Parker Alex Watson

Theses and Dissertations

Watson, Parker Alex, Effects of shrub encroachment and removal on South Texas coastal prairie flora. Master of Science, December, 2015. 60 pages, 14 tables, 11 figures, 47 references, 5 appendices. Native-invasive honey mesquite (Prosopis glandulosa) and huisache (Acacia farnesiana) are aggressively encroaching onto South Texas coastal prairies, outcompeting Gulf cordgrass (Spartina spartinae) and associated prairie vegetation with potential legacy effects on the landscape. To measure conditions in the presence of shrubs, data loggers were installed for 16 mos in shrub understories and grass cover to monitor light, soil and air temperatures. Vegetation and canopy surveys were also conducted to evaluate …

Economic Feasibility Of Aquaponics In Arkansas, Leah Ashley English

Graduate Theses and Dissertations

Concerns regarding population growth and resource scarcity have led to a recent renaissance of food production research. Over the past few decades, scientists have discovered new and innovative methods for growing food that, cumulatively, may hold the key to efficiently and sustainably feeding an ever-increasing world population. One method, known as aquaponics, has shown promise as being a sustainable solution for producing food locally in all parts of the world. Although many studies have shown aquaponic food production to be technically feasible, there are relatively few studies concerning the economic feasibility of aquaponics in various regions. To determine whether aquaponics …

A Regional Approach To Analysis Of Food Security Framework And Policies Of The Economic Community Of West African States (Ecowas), Hannah Elizabeth Shear

Graduate Theses and Dissertations

Food security is always a concern for consumers, but especially for those in West Africa, where the population of food insecure people has continued to grow over the past decade despite attempts by initiatives such as the World Food Program and the establishment of Millennium Development Goals. The people of West Africa are subject to repetitive natural disasters and are often in political upheaval. Many economic policies have been established to mitigate the impact that production disasters have on the consumers; one of these policies is the utilization of regional food reserves.

In 2010, the Economic Community of West African …

Evaluating The Impacts Of Respondent Errors In Arms: A Case Of Farm Service Agency Loans, Louise Nicole Mcminn

Graduate Theses and Dissertations

Many studies have used the U.S. Department of Agriculture’s (USDA) Agricultural Resource Management Survey (ARMS) to research various aspects involving the agricultural sector in the United States. Since nonresponse and inaccurate reporting may cause significant bias in statistical analysis, research was conducted to determine the magnitude of response error on the farm debt section of the ARMS Phase III. A multinomial logit model identified demographic, structural, and financial characteristics of FSA Farm Loan Program (FLP) borrowers who refused to indicate if they had end of year farm debt, or who accurately or inaccurately classified their farm operations as having end …

Eicosapentaenoic Acid (Epa) From Porphyridium Cruentum: Increasing Growth And Productivity Of The Microalgae For Pharmaceutical Products, Maryam Asgharpour

Graduate Theses and Dissertations

One of the major nutritional requirements in our diet is an adequate intake of omega-3 specially eicosapentaenoic acid (EPA). In the present study, the effects of two temperatures (16°C & 20˚C) and light intensities (140 & 180µE/M2.S) and four nitrate levels (0.075, 0.3, 0.5 and 0.7g/L) on the cell growth and lipid productivity of Porphyridium cruentum, one of the most promising oil-rich species of microalgae, were investigated. A growth comparison was carried out using pure CO2 and 5% CO2/air. Additionally, the ratio of the fatty acids with omega-3 and omega-6 groups at various growth conditions were compared, since an appropriate …

Cotton Injury Due To Soil- Or Foliar-Applied Herbicides: An Assessment Based On The Influences Of Genetic, Agronomic, And Environmental Factors, Brandon William Schrage

Graduate Theses and Dissertations

Increasing populations of glyphosate-resistant weeds, such as Palmer amaranth, have prompted growers to pursue alternative means of weed control in cotton. In many cropping systems, this means the utilization of older chemistries and residual herbicides. The goal of this research was to evaluate and understand the agronomic and environmental factors that affect the inconsistent injury often associated with these herbicides as well as determine the impact of Palmer amaranth emergence date on seed production, biomass, and cotton yield. Experiments were conducted in three counties in Arkansas giving a distinct range of climate and soil texture. Injury, biomass, and number of …

Applying Molecular And Phenotypic Tools To Characterize Flesh Texture And Acidity Traits In The Arkansas Peach Breeding Program And Understanding The Crispy Texture In The Arkansas Blackberry Breeding Program, Alejandra Andrea Salgado Rojas

Graduate Theses and Dissertations

Quantitative trait loci (QTL) utilizing a pedigree-based analysis (PBA) approach was performed in the peach breeding program for the first time. The pedigree consisted of seven-F1 populations, their parents, ancestors, and cultivars. Flesh firmness and titratable acidity (TA) were examined in 2011, 2012, and 2013. For TA, a consistent and strong QTL was identified on the proximal end of linkage group (LG) 5 of the peach genome. For flesh firmness, two QTLs were located on LG 4. The first QTL was located on the chromosomal region where the slow-melting flesh (SMF) DNA test was identified, and the second QTL was …

Calorimetry And Body Composition Research In Broilers And Broiler Breeders, Justina Victoria Caldas Cueva

Graduate Theses and Dissertations

Indirect calorimetry to study heat production (HP) and dual energy X-ray absorptiometry (DEXA) for body composition (BC) are powerful techniques to study the dynamics of energy and protein utilization in poultry. The first two chapters present the BC (dry matter, lean, protein, and fat, bone mineral, calcium and phosphorus) of modern broilers from 1 – 60 d of age analyzed by chemical analysis and DEXA. DEXA has been validated for precision, standardized for position, and equations and validations developed for chickens under two different feeding levels. These equations are unique to the machine and software in use. Research in broilers …

Validation Of Soil-Test-Based Phosphorus And Potassium Fertilizer Recommendations For Rice And Soybean, Matthew Scott Fryer

Graduate Theses and Dissertations

The science of soil-testing for nutrient management and fertilizer recommendations is widely accepted among scientists and agronomists. Although this science is unsurpassed in predicting soil nutrient availability, soil-test interpretations are seldom validated. Major research objectives for irrigated soybean [Glycine max (L.) Merr.] and direct-seeded, delayed-flood rice (Oryza sativa L.) were to: i) validate the accuracy of Mehlich-3 soil-test P (STP) and K (STK) interpretations and ii) published critical tissue-P and -K interpretations in predicting the yield response to fertilizer at different significance levels (p≤0.05 to 0.25), iii) examine how seed nutrient concentrations are influenced by fertilization and crop response to …

Composition Of Four Selected Arkansas-Grown Non-Gmo Soybean Cultivars And The Development Of High Protein Beverage Using A Selected Soybean Protein Hydrolysate, Quyen Tran Phuong Nguyen

Graduate Theses and Dissertations

Protein beverages made with non-genetically modified (non-GM) ingredients have been in demand due to the increasing consumers’ interest in healthy eating habit. Beverages formulated with non-GM soy protein are rare in the United States market since 93% soybeans planted in U.S (2013) are labeled as GM. This study aimed to develop protein hydrolysate beverages using one cultivar among the four Arkansas grown non-GM soybean cultivars including Osage, R95-1705, R08-4004 and R05-4969. R08-4004 was selected since it had the highest amounts of the three branched amino acids including Phenylalanine (51.4 mg/g), Leucine (74.9 mg/g), and Isoleucine (49.7 mg/g) with lowest amount …

Response Of Bacterial Cells To Fluctuating Environment, Sudip Nepal

Graduate Theses and Dissertations

We have studied morphological and genomic variations occurring in a mesophilic bacterium Escherichia coli (E. coli) in a wide range of continuous and fluctuating hydrostatic pressures. For all the studies here the temperature is maintained at 37◦C, the optimal growth tem- perature of E. coli at atmospheric pressure. Cell division is inhibited at high hydrostatic pressures resulting in an increase of cell length. The increase of cell-length depends on the extent and duration of the stress applied on bacterial cells. We have studied the effect of high pressure stress in three different conditions – (i) Wild-type cells (almost no genetic …

Available Nitrogen And Denitrification In Soil Altered By Ground Cover And Nutrient Source In An Organic Apple Orchard, Jade Nicole Ford

Graduate Theses and Dissertations

A shift in public demand towards more organic and locally produced fruit and vegetables has been occurring across the United States in recent years. A common practice in organic fruit production is the application of organic ground covers to supply nutrients while enhancing other soil properties. A need for research exists in the southern region of the U.S. examining the effects of regionally applicable ground cover and nutrient management on nitrogen availability and the microbial community to provide information to organic farmers in the region. Two studies were conducted to determine how 12 treatment combinations of four ground covers (compost, …

Stink Bugs: Spatial Distribution, Pecan Phenological Susceptibility And Sampling Program, Brian Cowell

Graduate Theses and Dissertations

An effective management program for stink bugs (SBs) in pecan groves requires knowledge of: stages of the pecans susceptible to SB damage; strata of the tree with SB damaged nuts; a practical SB monitoring method; and, effects of landscapes contributing SBs into pecan groves.

Stink bugs produced feeding punctures in pecan shucks at all phenological stages. Pecans punctured before the dough stage drop from the tree. Kernel damage occurs in the pecans’ dough stage, whereas mature pecans are not damaged.

The pecans collected from the whole tree using the tree shaker had significantly less punctures than the pecans collected from …

Balanus Eburneus (Crustacea: Cirripedia) As A Potential Indicator Of Estuarine System Recovery In South Texas: A Study Of Recruitment, Growth And Stable Isotopes, Crystal Martinez

Theses and Dissertations

Population characteristics of the barnacle Balanus eburneus were analyzed with the purpose of exploring its potential use as a discriminating indicator among sites exhibiting different disturbances or stages of recovery. The study was conducted from May 2012 to May 2013 at four estuaries in the Lower Laguna Madre, TX including a) Bahia Grande, currently under restoration and divided into Bahia Grande North and Bahia Grande South, b) San Martin Lake, which receives runoff water and c) South Bay, a relatively undisturbed reference estuary. In general, similar barnacle recruitment and growth trends in Bahia Grande South and South Bay were explained …

Autophagy And Its Potential Role In Stress And Feed Efficiency Using Avian Lines, Alissa Laura Piekarski

Graduate Theses and Dissertations

Autophagy is a highly conserved cellular mechanism that is responsible for the degradation and recycling of damaged organelles. Recently, autophagy has been involved in critical roles during overall development of the organism and degradation of damaged cellular components. This pathway has witnessed dramatic growth in the last few years and has been extensively studied in yeast and mammals, however, there is a paucity of information in avian (non-mammalian) species. First, we characterized genes involved in the autophagy pathway in male and female Jungle Fowl to determine gender and tissue specific differences. Secondly, tissue and genotype differences in Japanese quail selected …

Field Screening Of Diverse Soybean Cultivars For Flood Tolerance, Jane Achando Khatenje Mokua

Graduate Theses and Dissertations

Flooding can significantly reduce soybean growth, development, and yield. Therefore, screening and identification of flood-tolerant soybeans will enhance development of cultivars that are well suited for flood-prone areas. Sets of screening tests were conducted in Stuttgart, Arkansas using three separate but related experiments, with the purpose of establishing effective flood tolerance screening protocol that can identify tolerant and sensitive cultivars. Each experiment was completely randomized with three replications. The first experiment involved screening of 256 maturity group (IV and V) cultivars. Flooding was imposed at the fifth-node (V5) or first-bloom (R1) stage for ten days. Post-flood visual ratings and stand …

Microbial Safety, Shelf Life Stability, Quality Preservation, And Consumer Acceptance Of Vacuum-Infused, Irradiated Chicken Breast Meat Treated With Natural Plant Extracts And Organic Acids, Kenneth Franklin Over

Graduate Theses and Dissertations

Contamination of poultry products with food borne pathogens is a consistently recurring problem in the United States and the world. Recalls associated with chicken contamination are responsible for considerable economic losses to the poultry industry. Many decontamination steps are currently in place to reduce the likelihood of contaminated products reaching the consumer, but despite these safeguards, contamination events are still uncomfortably frequent. Irradiation is a safe and effective means of ensuring the safety of both ready-to-cook and ready-to-eat poultry but is not utilized in the United States. This is due, in part, to certain irradiation dose-dependent quality characteristic defects associated …

Sampling Terrestrial Arthropod Biodiversity: A Case Study In Arkansas, Michael Joseph Skvarla

Graduate Theses and Dissertations

The Interior Highlands is a biodiversity hotspot, with at least 200 known endemic species, but is understudied compared to hotspots, such as the Southern Appalachians. In order to begin to rectify this issue, a nine month study was conducted from mid-March through early December at a 4 ha site at Steel Creek, Buffalo National River, in Newton County, Arkansas. Thirteen collecting methods were employed, including three colors of Lindgren funnel trap, five colors of pan trap, Malaise traps, canopy traps with upper and lower collectors, pitfall traps, and Berlese-Tullgren extraction of leaf litter, which resulted in the collection of 1311 …