Agriculture Commons^™

Plant Cell Wall Composition And In Vitro Fermentation Characteristics Of Cool-Season Forage Grasses From Two Growing Seasons In Central Kentucky, Sophia Danielle Newhuis

Theses and Dissertations--Animal and Food Sciences

Grass cell walls are rich in cellulose, hemicellulosic arabinoxylan (AX) polysaccharides, and lignin. AX structural differences such as degree and pattern of branching and the ester-linked phenolic acid content could affect plants’ digestibility when used as forage for livestock. However, there is little information about how these structural elements change over the growing season in the vegetative tissue of cool-season perennial grasses. Enhanced information about the cell wall composition and carbohydrate structure of forage material will provide a foundation for expanding our knowledge of how forage cell wall carbohydrate structures are utilized by ruminants. The objectives of this study were …

Epigenetic Regulation Of Hormone Action In The Red Flour Beetle, Tribolium Castaneum (Herbst), Smitha George

Theses and Dissertations--Entomology

Hormones are the chemical communication signaling molecules released into the body fluid to stimulate target cells of multicellular organisms. Two major hormones, ecdysteroids (20-hydroxyecdysone, 20E) and juvenile hormones (JH), regulate a wide variety of physiological and developmental processes in insects. Therefore, hormones have been extensively studied and are attractive targets for the development of target-specific insect control methods. Recent studies suggest that epigenetics adds another layer of regulation to explain multiple functions of the same circulating hormone in different tissues and at various time points. In my dissertation, I focused on a major post-translational modification, ‘acetylation,’ to elucidate the epigenetic …

Host Restriction Factors In The Replication Of Tombusviruses: From Rna Helicases To Nucleocytoplasmic Shuttling, Cheng-Yu Wu

Theses and Dissertations--Plant Pathology

Positive-stranded (+)RNA viruses replicate inside cells and depend on many cellular factors to complete their infection cycle. In the meanwhile, (+)RNA viruses face the host innate immunity, such as cell-intrinsic restriction factors that could block virus replication.

Firstly, I have established that the plant DDX17-like RH30 DEAD-box helicase conducts strong inhibitory function on tombusvirus replication when expressed in plants and yeast surrogate host. This study demonstrates that RH30 blocks the assembly of viral replicase complex, the activation of RNA-dependent RNA polymerase function of p92pol and viral RNA template recruitment.

In addition, the features rendering the abundant plant DEAD-box helicases either …

Influence Of Dietary Ractopamine And Supranutritional Supplementation Of Vitamin E On Proteome Profile Of Postmortem Beef Longissimus Lumborum Muscle, Hyun Mok Kim

Theses and Dissertations--Animal and Food Sciences

The effects of dietary ingredients on the proteome profile of postmortem beef longissimus lumborum (LL) muscle were evaluated. In the first experiment, the influence of dietary ractopamine on the whole-muscle proteome of beef LL was examined. Five proteins were differentially abundant between ractopamine-fed (RAC) and non-ractopamine fed (CON) groups. The differentially abundant proteins were over-abundant in RAC and were related to muscle structure development (F-actin-capping protein subunit beta-2 and PDZ and LIM domain protein-3), chaperone (heat shock protein beta-1), oxygen transportation (myoglobin), and glycolysis (L-lactate dehydrogenase A chain). These findings indicated that ractopamine influences the abundance of proteins associated with …

Nuclear Import And Interactions Of Potato Yellow Dwarf Virus Nucleocapsid, Matrix, And Phosphoprotein, Gavin Lloyd Franklin Anderson

Theses and Dissertations--Plant Pathology

Potato yellow dwarf virus (PYDV) is the type species of the genus Nucleorhabdovirus and, like all members of this genus, replication and morphogenesis occurs inside the nuclei of infected cells. Protein localization prediction algorithms failed to identify a nuclear localization signal (NLS) in PYDV nucleocapsid (N) protein, although PYDV-N has been shown to localize exclusively to the nucleus when expressed as a green fluorescent protein (GFP):N fusion in plant cells. Deletion analysis and alanine-scanning mutagenesis identified two amino acid motifs, ⁴¹⁹QKR⁴²¹ and ⁴³²KR⁴³³, that were shown to be essential for nuclear import and interaction with …

The Role Of Surface Chemistry In The Toxicity Of Manufactured Cerium Dioxide Nanomaterials To Caenorhabditis Elegans, Emily Kay Oostveen

Theses and Dissertations--Plant and Soil Sciences

Manufactured CeO₂ nanomaterials (CeO₂-MNMs) are used for a wide variety of applications including diesel fuel additives and chemical/mechanical planarization media. To test the effects of CeO₂-MNM surface coating charge on to model organism Caenorhabditis elegans, we synthesized 4 nm CeO₂ with cationic (DEAE-), anionic (CM-), and neutral (DEX) coatings. In L3 nematodes exposed for 24 hours, DEAE-CeO₂ induced lethality at lower concentrations than CM- or DEX-CeO₂. Feeding slightly decreased CeO₂ toxicity, regardless of coating. In L2 nematodes exposed for 48 hours with feeding, DEAE-CeO₂ caused lethality at the …

Enantioselective Demethylation: The Key To The Nornicotine Enantiomeric Composition In Tobacco Leaf, Bin Cai

Theses and Dissertations--Plant and Soil Sciences

Nicotine and nornicotine are the two main alkaloids that accumulate in Nicotiana tabacum L. (tobacco), and nornicotine is the N-demethylation metabolite of nicotine. Nicotine is synthesized in the root, and probably primarily in the root tip. Both nicotine and nornicotine exist as two isomers that differ from each other by the orientation of H atom at the C-2' position on the pyrrolidine ring. (S)-nicotine is the dominant form in tobacco leaf and the enantiomer fraction of nicotine (EF_nic), the fraction of (R)-enantiomer over the total nicotine, is approximately 0.002. Despite considerable efforts to elucidate nicotine and nornicotine …