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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

A tripartite study on climate change, nitrogen-sulfur interactions, and sulfur’s role in Mississippi corn production

Sharma, Ramandeep Kumar 10 May 2024 (has links) (PDF)
Three studies were conducted with the objectives as i) to assess the impact of climate change on Mississippi (MS) corn production using 1970 to 2020 datasets, employing autoregressive distributed lag model (ARDL), ii) A narrative review on the role of sulfur (S) in crop production, and iii) to investigate the corn response to multiple rates of nitrogen (N) and S. The first study findings revealed that the maximum temperature and precipitation had a negative effect on MS corn yield while minimum temperature and CO2 emissions posed a positive effect on corn yield. The second review study discussed the need for exploring the improvements required in S uptake, S use efficiency, systematic S fertilizing strategies, and precise and timely S diagnostic tools. Third study was a field experiment conducted at four-site years in 2021 and 2023 at Starkville, Brooksville, and Stoneville, Mississippi (MS) using a randomized complete block design with four replications. Treatments included 0, 112, 224, and 336 kg N ha-1 and 0, 22, 44, and 66 kg S ha-1, and their interactions. The key findings of this study were i) N x S interaction affected S agronomic efficiency (SAE) and S partial factor productivity (SPFP) at all site-years, N partial factor productivity (NPFP) at 2 site-years, and N leaf uptake (NLF), ear height, and grain oil at 1 site-year, ii) N-only treatments influenced grain yield, N agronomic efficiency (NAE), N grain uptake (NGR), protein, starch, seed index at all site-years, N uptake in leaf (NLF) and S uptake in leaf (SLF) at 3 site-years, and N partial factor productivity (NPFP), plant and ear height, stalk diameter, leaf area index (LAI), grain oil and S uptake in grain (SGR), at 2 site years, iii) S only treatments influenced starch at 2 site-years, and grain yield, N agronomic efficiency (NAE), protein, seed index, N uptake in grain (NGR), and S uptake in leaf (SLF) at 1 site-year. Although the response of S was less frequent at all the tested parameters, current findings indicated the vitality of S fertility for all parameters except growth parameters.
12

A novel approach to circumvent P-glycoporotein mediated cellular efflux and permeability enhancement of HIV protease inhibitor saquinavir

Jain, Ritesh, Mitra, Ashim K., January 2007 (has links)
Thesis (Ph. D.)--School of Pharmacy. University of Missouri--Kansas City, 2007. / "A dissertation in pharmaceutical science and pharmacology." Advisor: Ashim K. Mitra. Typescript. Vita. Title from "catalog record" of the print edition Description based on contents viewed July 16, 2008. Includes bibliographical references (leaves 231-248). Online version of the print edition.
13

A role for HSC70 in regulating antigen trafficking and presentation during macronutrient deprivation

Deffit, Sarah N. 02 1900 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Globally, protein malnutrition remains problematic, adversely affecting several systems including the immune system. Although poorly understood, protein restriction severely disrupts host immunity and responses to infection. Induction of high-affinity, long-lasting immunity depends upon interactions between B and T lymphocytes. B lymphocytes exploit several pathways including endocytosis, macroautophagy, and chaperone-mediated autophagy to capture and deliver antigens to the endosomal network. Within the endosomal network antigens are processed and loaded onto major histocompatibility complex (MHC) class II molecules for display and recognition by T lymphocytes. To examine the effect of macronutrient malnutrition on MHC class II antigen presentation, we grew B lymphocytes in media containing amino acids, sugars and vitamins but lacking serum, which contains several types of macronutrients. Our studies show macronutrient stress amplified macroautophagy, favoring MHC class II presentation of cytoplasmic antigens targeted to autophagosomes. By contrast, macronutrient stress diminished MHC class II presentation of membrane antigens including the B cell receptor (BCR) and cytoplasmic proteins that utilize the chaperone-mediated autophagy pathway. The BCR plays a critical role in MHC class II antigen presentation, as it captures exogenous antigens leading to internalization and degradation within the endosomal network. While intracellular protease activity increased with macronutrient stress, endocytic trafficking and proteolytic turnover of the BCR was impaired. Addition of high molecular mass macronutrients restored endocytosis and antigen presentation, evidence of tightly regulated membrane trafficking dependent on macronutrient status. Cytosolic chaperone HSC70 has been shown to play a role in endocytosis, macroautophagy, chaperone-mediated autophagy and proteolysis by the proteasome, potentially connecting distinct routes of antigen presentation. Here, altering the abundance of HSC70 was sufficient to overcome the inhibitory effects of nutritional stress on BCR trafficking and antigen presentation suggesting macronutrient deprivation alters the availability of HSC70. Together, these results reveal a key role for macronutrient sensing in regulating immune recognition and the importance of HSC70 in modulating distinct membrane trafficking pathways during cellular stress. These results offer a new explanation for impaired immune responses in protein malnourished individuals.
14

Kinetic Analysis of Primate and Ancestral Alcohol Dehydrogenases

Myers, Candace R. 29 November 2012 (has links)
Indiana University-Purdue University Indianapolis (IUPUI) / Seven human alcohol dehydrogenase genes (which encode the primary enzymes involved in alcohol metabolism) are grouped into classes based on function and sequence identity. While the Class I ADH isoenzymes contribute significantly to ethanol metabolism in the liver, Class IV ADH isoenzymes are involved in the first-pass metabolism of ethanol. It has been suggested that the ability to efficiently oxidize ethanol occurred late in primate evolution. Kinetic data obtained from the Class I ADH isoenzymes of marmoset and brown lemur, in addition to data from resurrected ancestral human Class IV ADH isoenzymes, supports this proposal--suggesting that two major events which occurred during primate evolution resulted in major adaptations toward ethanol metabolism. First, while human Class IV ADH first appeared 520 million years ago, a major adaptation to ethanol occurred very recently (approximately 15 million years ago); which was caused by a single amino acid change (A294V). This change increases the catalytic efficiency of the human Class IV enzymes toward ethanol by over 79-fold. Secondly, the Class I ADH form developed 80 million years ago--when angiosperms first began to produce fleshy fruits whose sugars are fermented to ethanol by yeasts. This was followed by the duplication and divergence of distinct Class I ADH isoforms--which occurred during mammalian radiation. This duplication event was followed by a second duplication/divergence event which occurred around or just before the emergence of prosimians (some 40 million years ago). We examined the multiple Class I isoforms from species with distinct dietary preferences (lemur and marmoset) in an effort to correlate diets rich in fermentable fruits with increased catalytic capacity toward ethanol oxidation. Our kinetic data support this hypothesis in that the species with a high content of fermentable fruit in its diet possess greater catalytic capacity toward ethanol.

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