Life Sciences Commons^™

Effects Of Extrinsic And Intrinsic Factors On Meat Quality And Muscle Biology Of Livestock, Yongjie Wang

Graduate Theses and Dissertations

In order to improve the meat quality of livestock, intrinsic and extrinsic factors that impact meat quality have been studied for a long time to optimize production quality. Nutrition, breed, and environment are the three most common factors to improve meat quality and muscle growth. The objective of this thesis is to perform a horizontal comparison of the effects of crude protein levels, breeds, and topsoil on the growth performance, muscle development, and meat quality of livestock, and also a longitudinal analysis using RNA-seq, RT-qPCR, and Western-blot to investigate the changes in genes and proteins related to muscle growth, and …

Genetic Resistance To The Downy Mildew Pathogen And Breeding Towards Durable Disease Management In Spinach, Bazgha Zia

Graduate Theses and Dissertations

Spinach (Spinacia oleracea) is a self-pollinated, dioecious winter crop. Prevalent challenges to the production of spinach include disease pressure imposed by downy mildew, which is caused by Peronospora effusa (=P. farinosa f. sp. spinaciae [Pfs]). A total of 19 new races of P. effusa have emerged, imposing serious challenges to the disease management in spinach production. Accordingly, this study was designed to explore the genetic components for establishing the basis of durable disease resistance development against the downy mildew pathogen (P. effusa 13) in spinach, through the use of various genome engineering approaches.

Our results have led (Chapter 2) to …

Functional And Physiological Role Of Extra-Hypothalamic Corticotropin Releasing Hormone Neurons In The Nucleus Of The Hippocampal Commissure In Regulation Of Stress Response, Hakeem Kadhim

Graduate Theses and Dissertations

Corticotropin releasing hormone (CRH) neurons located within the paraventricular nucleus (PVN) are known to be involved in regulation of stress responses. Recently, CRH neurons were identified above the PVN within the nucleus of the hippocampal commissure (NHpC) that located in the septum. We hypothesized that CRH neurons in the NHpC play a critical role in the stress response due to their rapid activation and could be a part of the traditional hypothalamo-pituitary-adrenal (HPA) axis. The dissertation addresses the role of 1) CRH expressing neurons in the NHpC compared with those within the PVN utilizing two different stressors, food deprivation (FD) …

Investigating The Potential Of Plant-Derived Antimicrobials For Controlling Campylobacter Jejuni In Poultry And Poultry Products, Basanta Raj Wagle

Graduate Theses and Dissertations

Campylobacter jejuni infection in humans is strongly associated with the handling and consumption of contaminated poultry products. Interventions reducing C. jejuni contamination in poultry would reduce the risk of subsequent human infections. In the first study, the efficacy of a Generally Recognized as Safe (GRAS) compound, eugenol (EG; derived from cloves), as an antimicrobial dip treatment to reduce C. jejuni in postharvest poultry was evaluated. The antimicrobial efficacy of EG was studied in suspension, emulsion and nanoemulsion delivery systems. EG suspension reduced C. jejuni counts with the greatest reduction of >2.0 Log CFU/sample for the 2% dose of EG (P<0.05). Eugenol emulsions or nanoemulsions did not provide any additional Campylobacter reduction when compared with suspension alone. In the second study, the efficacy of pectin or chitosan coatings fortified with eugenol to reduce C. jejuni on chicken wingettes was investigated. Inoculated wingettes were randomly assigned to controls, eugenol (0.5, 1 or 2%), pectin (3%), chitosan (2%) or their combinations. Following 1 min of coating, wingettes were air dried (1 h) and sampled on d 0, 1, 3, 5, and 7. The incorporation of 0.5, 1 or 2% eugenol in the pectin improved coating efficacy against C. jejuni whereas the efficacy of chitosan coating was improved by 2% eugenol treatment (P<0.05). Exposure of C. jejuni to eugenol, chitosan or combination significantly modulated select genes encoding for motility, quorum sensing and stress response. In the third study, the efficacy of eugenol, trans-cinnamaldehyde and carvacrol in inhibiting C. jejuni biofilm formation and inactivating mature biofilm was evaluated. For the inhibition study, C. jejuni was grown either in the presence or absence of sub-inhibitory concentrations of phytochemicals and biofilm formation was quantified at 24 h intervals by enumeration. For the inactivation study, mature C. jejuni biofilms were exposed to the phytochemicals (0, 0.25, 0.5, or 1%) for 1, 5, or 10 min, and surviving C. jejuni in the biofilms were enumerated. All phytochemicals reduced C. jejuni biofilm formation as well as inactivated mature biofilm at both temperatures (P<0.05). Moreover, scanning electron microscopy revealed disruption of biofilm architecture and loss of extracellular polymeric substances after treatment.

Phenotypic And Gene Expression Analysis Of Diverse Rice Genotypes In Response To Drought, Miranti Rahmaningsih

Graduate Theses and Dissertations

Drought is one of the most limiting factors for rice (Oryza sativa L.) growth and development with vegetative and reproductive stages the most sensitive and distinct phases. During the vegetative stage, drought can cause reduction in growth and biomass accumulation. Moreover, water stress at reproductive stage can reduce yield significantly. Plants are protected against drought by three different mechanisms: drought avoidance, drought tolerance, and drought escape. An integrated approach combining physiology, breeding, and genomics could be an effective way to characterize and mitigate this problem. The objectives of this research were to (1) screen a diverse set of rice genotypes …

Gene Expression And Physiological Analysis To Study Differences Between Oryza Sativa Cultivars Susceptible And Resistant To Chalky Grain Formation Subjected To High Nighttime Temperatures., Nicholas Lawson

Graduate Theses and Dissertations

Starch composition and grain quality of rice is greatly influenced by genotype and environmental factors. The detrimental effects of high nighttime temperatures on rice yield and quality has recently become apparent, with some of the warmest average nighttime temperatures being recorded in the past few years. One of the most notable effects of this stress, an increase in grain chalk formation, correlates with a decrease in quality. This effect varies greatly between cultivars as some show less temperature-sensitive quality reduction than others. The goal of this research is to elucidate fundamental changes that occur in developing plants and grains as …

Study Of Thermotolerance Mechanism In Gossypium Hirsutum Through Identification Of Heat Stress Genes, Jin Zhang

Graduate Theses and Dissertations

ABSTRACT

Heat stress causes major losses to cotton seed and lint yield. Introduction of heat stress tolerance to Arkansas cotton varieties is highly desirable. However, very little is known about the molecular basis of heat stress tolerance in cotton. The present study attempted to identify heat stress tolerance genes in two heat-tolerant cotton cultivars, VH260 and MNH456, originating from Pakistan. Towards this, the expression profile of the cotton orthologs of sevenArabidopsisheat stress tolerance genes was studied in these two cultivars, and compared with the two heat-susceptible cotton cultivars, ST213 and ST4288, originating from Mississippi Delta region. In addition, physiological parameters …

Host-Virus Interactions Of Infectious Laryngotracheitis Virus Infection In Cultured Cells, Jeong Yoon Lee

Graduate Theses and Dissertations

Infectious laryngotracheitis virus (ILTV; Gallid herpesvirus 1) causes upper respiratory diseases in mainly chickens and exhibits 90-100% of high morbidity and up to 70% of mortality, resulting in huge economic losses in the poultry industry worldwide.

To study host-ILTV interactions, the changes in genome-wide gene expressions in response to wild-type and vaccine ILTV infections in primary chicken embryo lung cells were investigated using microarray analysis. Results provide crucial insights into host cell pathogenic and immunogenic responses against wild-type and vaccine ILTV infections. Using microarray method and Ingenuity Pathway Analysis (IPA) bioinformatics tool, 273 and 306 differentially expressed genes were identified …

Characterization Of Neuronal Groups Regulating Sexual And Agonistic Behavior In Male Chicken (Gallus Gallus), Jingjing Xie

Graduate Theses and Dissertations

The study aimed to understand the neuronal regulation of male sexual and agonistic behavior in broiler breeders. First, brain structures associated with sexual and agonistic behavior were identified by mapping Fos expression. The ventromedial subnucleus of medial portion of bed nucleus of the stria teriminalis (BSTM2) was specifically activated by male courtship behavior. The medial preoptic nucleus (POM) and lateral septum (SL) were associated with both sexual and agonistic behaviors. The bed nucleus of the pallial commissure (NCPa) and the paraventricular nucleus (PVN) were closely related to stress. Second, Fos-ir neurons were phenotyped by double labeling Fos with aromatase (ARO) …