Life Sciences Commons^™

Immune Outcomes Affected By Selection For Parasite Resistance In Katahdin Sheep, Kelsey Lynne Bentley

Graduate Theses, Dissertations, and Problem Reports

Our understanding of the complex connection between selection for parasite resistance and the overall health outcomes in livestock is unclear. This study investigates the impact of post-weaning fecal egg count (PFEC) estimated breeding values (EBV) on health outcomes and immune responses in Katahdin sheep. Selection for PFEC, favoring Low-PFEC lambs, not only affects survivability to weaning but also suggests broader implications for immunity beyond parasite resistance. The effect of PFEC EBV on antibody production in response to vaccination against Clostridium perfringens type C&D and tetanus toxoid (CD&T) revealed a stepwise decrease in immunoglobin (IgG) from Low-PFEC to High-PFEC groups upon …

Estradiol’S Role In Timely Puberty Onset In The Ewe, Eliana Gerardine Aerts

Graduate Theses, Dissertations, and Problem Reports

In female sheep, the release of gonadotropin-releasing hormone (GnRH) from the hypothalamus triggers luteinizing hormone (LH) to be released from the pituitary. Luteinizing hormone, in turn, acts on the ovaries to elicit estradiol (E₂) release. E₂ acts in a negative feedback manner to control the amount of LH released. The increase in LH release that drives puberty onset results from a decrease in sensitivity to E₂ as the animal ages. However, the neural mechanisms mediating this change in sensitivity are not known, as is where in the hypothalamus E₂-negative feedback occurs. In the arcuate …

Structural And Functional Consequences Of Pde6 Prenylation In Rod And Cone Photoreceptors, Faezeh Moakedi

Graduate Theses, Dissertations, and Problem Reports

Phosphodiesterase-6 (PDE6) serves as a pivotal component in the phototransduction pathways of both cone and rod photoreceptors. In cones, PDE6 consists of tetrameric subunits: inhibitory (γ') and catalytic (α'). The catalytic subunit, PDE6α', contains a C-terminal prenylation motif. Deletion of this motif is associated with achromatopsia (ACHM), a form of color blindness. The mechanisms underlying the disease and the roles of PDE6 lipidation in vision remain elusive. Meanwhile, rod PDE6 is composed of α and β catalytic subunits and γ inhibitory subunits, with alterations in the C-terminal "prenylation motif" of PDE6β linked to retinitis pigmentosa (RP) pathology. In this comprehensive …

Elucidation Of The Role Of Agouti-Signaling Protein Throughout Folliculogenesis And Early Embryonic Development In Cattle, Heather L. Chaney

Graduate Theses, Dissertations, and Problem Reports

The oocyte expresses certain genes during folliculogenesis to regulate the acquisition of oocyte competence. Oocyte competence, which refers to the presence of imperative molecular factors in the oocyte that are critical for high oocyte quality, is directly related to the ability of the oocyte to result in a successful pregnancy following fertilization. Over the past few decades, the development and optimization of assisted reproductive technologies, particularly in vitrofertilization, have enabled the beef and dairy industries to advance cattle genetics and productivity. However, only approximately 40% of bovine embryos will develop to the blastocyst stage in vitro. In addition, bovine embryos …

The Investigation Of Novel Bovine Oocyte-Specific Long Non-Coding Rnas And Their Roles In Oocyte Maturation And Early Embryonic Development, Jaelyn Zoe Current

Graduate Theses, Dissertations, and Problem Reports

Early embryonic loss is a significant factor in livestock species' infertility, resulting in an economic deficit. In cattle, the in vivo fertilization rate is ~90%, with an average calving rate of about 55%, indicating an embryonic-fetal mortality rate of roughly 35%. Further, 70-80% of total embryonic loss in cattle occurs during the first three weeks after insemination, particularly between days 7-16. Growing evidence indicates that the oocyte plays an active role in regulating critical aspects of the reproductive process required for successful fertilization, embryo development, and pregnancy. However, defining oocyte quality remains enigmatic. Recently, many have abandoned the notion that …

The Microvascular And Systemic Effects Of Titanium Dioxide Nanoparticle Exposure: A Physiological Perspective, Alaeddin Bashir Abukabda

Graduate Theses, Dissertations, and Problem Reports

Titanium dioxide nanoparticles (nano-TiO₂) are one of the most widely used engineered nanomaterials (ENM). Their ubiquitous inclusion warrants a more thorough understanding of their toxicity, particularly in sensitive populations such as pregnant women and the developing fetus.

The aim of the first study was to determine the most sensitive segments of the vasculature to pulmonary ENM exposure. Macrovascular function was investigated in the thoracic aorta, common femoral artery and 3^rd order mesenteric arterioles using wire myography. Microvascular function was assessed in 4^th and 5^th order mesenteric arterioles via pressure myography. Nano-TiO₂ exposure induced impairments …