Life Sciences Commons^™

Evaluation Of Negative Energy And Mineral Balance In Periparturient Holstein-Friesian Cattle, Ameer Ahmed Abdelhameed

Open Access Dissertations

Most cows experience a state of negative energy and mineral balance during the periparturient period. This imbalance is a major problem in the dairy industry and it is more frequently seen in multiparous cattle due to their high milk production. A large amount of fat and protein is mobilized in order to address the energy deficit during the periparturient period. The ability to accurately monitor energetics and electrolytes status using accurate, rapid, and low cost point-of-care instruments will assist in optimizing animal health and productivity.

This dissertation contains three studies that evaluated point-of-care instruments for measuring blood and plasma glucose, …

Natural Genetic Variation Affecting Calcium Homeostasis, Rebecca Anna Replogle

Open Access Dissertations

Calcium (Ca) is essential for multiple functions within the body including skeletal health. The level of Ca in the serum is tightly regulated. During periods of habitual low Ca intake, the body senses a decrease in serum Ca and increases renal conversion of 25 hydroxyvitamin D (25(OH)D) to 1,25 dihydroxyvitamin D (1,25(OH)2D). 1,25(OH)2D acts through the vitamin D receptor (VDR) to increase intestinal Ca absorption, renal Ca reabsorption and skeletal Ca resorption. Efficient intestinal Ca absorption, especially during periods of low Ca intake, is critical for protecting bone mass. Ca absorption and its primary regulator, 1,25(OH)2D, are affected by both …

Store-Operated Calcium Entry And Its Function During Fertilization In Porcine Eggs, Chunmin Wang

Open Access Dissertations

In a variety of mammalian cells, the depletion of intracellular Ca^{2+ stores leads to Ca2+ influx across the plasma membrane though a process known as store-operated Ca2+ entry. It not only plays a critical role in the replenishment of the Ca2+ stores but it is also responsible for the maintenance of long-lasting high intracellular Ca2+ levels and sustaining repetitive Ca2+ oscillations. During fertilization a Ca2+ signal, which can take the form of a single or multiple Ca2+ elevations (depending on the species) is the universal trigger for the egg-to-embryo transition. For sustaining …}

Characterization Of Caxck31, A Bacterial Calcium/Proton Antiporter, Marc Robert Ridilla

Open Access Dissertations

To better understand a class of transporters known as Calcium/Cation Antiporters (CaCAs), the bacterial calcium/proton antiporter CAXCK31 was purified and characterized. New methods were developed for its heterologous overexpression and purification. These methods help to define stress responses to toxic membrane overproduction in E. coli and may be broadly applicable to studies of membrane proteins. The results from a variety of biochemical and biophysical experiments demonstrated that CAXCK31 exists as a dimer in the membrane and can be purified in the dimeric state. The methods used include chemical cross-linking, FRET, and SEC-MALS. In addition, various transport properties of CAXCK31, including …