Browsing by Subject "Phosphate"
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Item Combining recognition motifs for improved sensing and biological activity of phosphorylated molecules(2010-08) Hargrove, Amanda E.; Sessler, Jonathan L.; Anslyn, Eric V., 1960-; Ellington, Andrew D.; Peppas, Nicholas A.; Brodbelt, JenniferPhosphorylated molecules play vastly important roles in the environment and biological systems. The main focus of this work sought to expand the current collection of synthetic phosphate receptors to include the binding of oligosaccharide phosphates. To this end, the synthesis of a boronic acid - appended porphyrin whose selectivity could be tuned through nucleic acid selection was pursued through a number of synthetic routes. Though difficulties were encountered with synthetic reactivities and product solubility, these efforts culminated in the development of a bis-boronic acid-substituted porphyrin soluble in DMSO/water mixtures that displays fluorescence quenching upon the addition of specific saccharide derivatives. In efforts to ease the synthetic burden, the creation of a DNA-based self-assembled receptor system was also investigated. Further, this work included the synthesis of phosphorylated derivatives of gemcitabine, a nucleoside chemotherapeutic drug, with the goal of developing targeted delivery systems for the improved treatment of cancer. Progress in each of these areas is discussed.Item Genetic basis for ichthyotoxicity and osmoregulation in the euryhaline haptophyte, Prymnesium parvum N. Carter(2014-05) Talarski, Aimee Elizabeth; La Claire, John W., 1951-There is limited information currently available regarding the underlying physiological responses and molecular mechanisms of osmoregulation, acetate metabolism [in relation to the synthesis of glycerolipids, polyunsaturated fatty acids (PUFA), and ichthyotoxins], and transport in Prymnesium parvum N. Carter, a microalga that causes devastating harmful algal blooms (HAB) worldwide. This dissertation examines gene expression under environmental conditions that are associated with HAB formation, including phosphate limitation and low salinity, using microarrays and RNA sequencing (RNA-Seq). A comparative fatty acid methyl ester (FAME) analysis at 30 vs. 5 practical salinity units (psu) was performed to gain additional insight into acetate metabolism. The RNA-Seq analysis included a de novo assembly of the P. parvum transcriptome, generating 47,289 transcripts, of which 35.4% were identifiable. This permitted the evaluation of the expression of many more genes compared with the microarray analysis, which examined ~3,500 genes. Relevant candidate genes identified included those whose products are involved in osmolyte production, salinity stress, and ion transport. With respect to the putative synthesis of polyketide ichthyotoxins, 32 different polyketide synthase (PKS) transcripts were identified in the transcriptome assembly, none of which were differentially expressed. Hemolysin and monogalactosyldiacylglycerol synthase were downregulated at 30 vs. 5 psu, suggesting the increased presence of additional ichthyotoxins at the lower salinity. Evidence for several PUFA synthesis pathways was also revealed. Fatty acid compositions were largely similar at the two salinities, containing relatively prominent quantities of the PUFA stearidonic acid, but compositions varied among strains. The transcription of genes whose products are associated with vesicular transport was elevated, and higher levels of extracellular prymnesins were observed in HAB-forming conditions. Thus, with regard to acetate metabolism, I have revealed evidence for the post-transcriptional regulation of the production of prymnesins and the contributory effects of hemolysin, monogalactosyldiacylglycerol, and PUFA towards ichthyotoxicity. Further, I propose that toxin transport is triggered in HAB-forming conditions, in which the toxins are actively being excreted. Collectively, these data shed light on the transcriptional responses that occur following alterations in phosphate availability and salinity, including those associated with the synthesis and delivery of a number of potential ichthyotoxins from P. parvum.Item Live Imaging of Subcellular Phosphate Pools in Plants(2013-11-25) Mukherjee, PallaviPlants modulate photosynthesis and the subsequent fate of fixed carbon throughout each day to ensure that immediate carbon needs are met and that sufficient stores are available for the coming night. Although these processes are restricted to chloroplasts they must be tightly coordinated with metabolic pathways in the surrounding cytosol and ultimately, in distant cells within nonphotosynthetic parts of the plant. Inorganic phosphate (Pi) is a key determinant of metabolic status, and I hypothesize that the transport of inorganic phosphate (Pi) between the chloroplast and cytosol integrates metabolism in these cell compartments. PHT2;1 and PHT4;4 are unrelated Pi transporters that localize to the chloroplast inner membrane. Although I predicted that these proteins would be functionally redundant, the corresponding loss-of-function mutants exhibit opposite phenotypes with respect to biomass and starch accumulation. Based on these observations, I hypothesize that PHT2;1 and PHT4;4 transport Pi in opposite directions and that these proteins provide fine-tuning of Pi levels in the chloroplast. Because no suitable analytical technique existed to address this hypothesis I developed and optimized a series of genetically encoded fluorescent Pi biosensors for use in live plants. I confirmed that these biosensors could be targeted to different cell compartments and confirmed their utility for monitoring Pi concentrations in the cytosol and plastid stroma.Item Savorphos as an All Natural Phosphate Replacer in Water and Oil Based Marinades for Rotisserie Birds and Boneless-Skinless Breast(2013-05-03) Casco Montenegro, GerardoAs consumer demand for all-natural marinades increases, the need to replace phosphate with a natural product that can produce equivalent or improved yield in products such as but not limited to rotisserie chickens (RWOG) and boneless/skinless breast (BSB) is a challenge for processors. The objective of this study was to determine if using an all-natural non-phosphate blend (savorphos-200, SP) in water-based (WB) and oil-based (OB) marinades would perform better in quality and yield parameters than a commercial phosphate blend (PB). The treatments included WB+PB (water, 0.4% phosphate, 0.7% salt), WB+SP (water, 0.5% savorphos-200, 0.7% salt), OB+PB (water, 3% canola oil, 0.4% phosphate, 0.7% salt), and OB+SP (water, 3% oil, 0.5% savorphos-200, 0.7% salt). RWOG and BSB were injected with a multi-needle injector to 20% (wt/wt) pick-up at a constant pressure (15-20 psi). The parameters measured were marinade pick-up %, 20 min and 24 hr marinade retention %, and cook loss %. Color, tenderness, total moisture, and sensory test were conducted on BSB. Data were analyzed within marination type (WB and OB). Results for the RWOG indicated SP obtained higher pick-up yield (p<0.05) and lower cook loss in the OB marinade compared to the PB. For the BSB, pick-up yield on OB marinades are higher for SavoPhos (p<0.05) when compared to the PB. On WB marinades cook loss was lower on SavorPhos compared to the PB. On RWOG and BSB variability is lower for SP on pick-up and 20 min retention yield values. Texture shear values were lower (p<0.05) on SP samples when compared to the PB. A consumer triangle sensory test was not able to distinguish between treatments (p>0.05). Therefore, savorphos-200 can be used as a natural non-phosphate blend in water based marinades with no detriment to yield. In addition, savorphos-200 can be used as a natural non-phosphate blend in oil-based marinades with yield improvements.