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Increased investigation into the development of macromolecular fluorophores has resulted in the synthesis and discovery of several potential candidates. These include modified and polymeric based dendritic structures, hyperbranched polymers and linear polymers. Strong inherent blue photoluminescence has been recently described in linear polyamine polymers in the absence of any chemical

Increased investigation into the development of macromolecular fluorophores has resulted in the synthesis and discovery of several potential candidates. These include modified and polymeric based dendritic structures, hyperbranched polymers and linear polymers. Strong inherent blue photoluminescence has been recently described in linear polyamine polymers in the absence of any chemical modifications. Here we describe the screening of amine/polyamine compounds for inherent photoluminescence. Several compounds that exhibited strong inherent blue photoluminescence following excitation with UV light were identified. Furthermore we demonstrated successful synthesis of poly(amino ether) polymers as well as chemically cross-linked poly(amino ether) thermosets with the lead Pentaethylenehexamine which was found to have strong inherent blue photoluminescence. The polymers and thermosets were found to retain the photoluminescent properties of the original lead compound. The polymers and thermosets were investigated for their ability to sequester heavy metals from aqueous solutions. An increased decrease in initial photoluminescence was observed as the materials were incubated with increasing metal salt concentration as a result of metal binding sequestration. The poly(amino ether) polymers were found to have higher sensitivity for metal sequestration when compared to equivalent amount of linear 25 kDa polyethylenimine. The strong inherent blue photoluminescence and the ease of synthesis of the poly(amino ether) polymers and thermosets give these materials strong potential for future applications as sensors.
ContributorsVu, Jeffrey (Co-author) / Ramos, James (Co-author) / Rege, Kaushal (Thesis director) / Godeshala, Sudakhar (Committee member) / Barrett, The Honors College (Contributor) / Chemical Engineering Program (Contributor)
Created2015-05
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Neurotoxicology has historically focused on substances that directly damage nervous tissue. Behavioral assays that test sensory, cognitive, or motor function are used to identify neurotoxins. But, the outcomes of behavioral assays may also be influenced by the physiological status of non-neural organs. Therefore, toxin induced damage to non- neural organs

Neurotoxicology has historically focused on substances that directly damage nervous tissue. Behavioral assays that test sensory, cognitive, or motor function are used to identify neurotoxins. But, the outcomes of behavioral assays may also be influenced by the physiological status of non-neural organs. Therefore, toxin induced damage to non- neural organs may contribute to behavioral modifications. Heavy metals and metalloids are persistent environmental pollutants and induce neurological deficits in multiple organisms. However, in the honey bee, an important insect pollinator, little is known about the sublethal effects of heavy metal and metalloid toxicity though they are exposed to these toxins chronically in some environments. In this thesis I investigate the sublethal effects of copper, cadmium, lead, and selenium on honey bee behavior and identify potential mechanisms mediating the behavioral modifications. I explore the honey bees’ ability to detect these toxins, their sensory perception of sucrose following toxin exposure, and the effects of toxin ingestion on performance during learning and memory tasks. The effects depend on the specific metal. Honey bees detect and reject copper containing solutions, but readily consume those contaminated with cadmium and lead. And, exposure to lead may alter the sensory perception of sucrose. I also demonstrate that acute selenium exposure impairs learning and long-term memory formation or recall. Localizing selenium accumulation following chronic exposure reveals that damage to non-neural organs and peripheral sensory structures is more likely than direct neurotoxicity. Probable mechanisms include gut microbiome alterations, gut lining

damage, immune system activation, impaired protein function, or aberrant DNA methylation. In the case of DNA methylation, I demonstrate that inhibiting DNA methylation dynamics can impair long-term memory formation, while the nurse-to- forager transition is not altered. These experiments could serve as the bases for and reference groups of studies testing the effects of metal or metalloid toxicity on DNA methylation. Each potential mechanism provides an avenue for investigating how neural function is influenced by the physiological status of non-neural organs. And from an ecological perspective, my results highlight the need for environmental policy to consider sublethal effects in determining safe environmental toxin loads for honey bees and other insect pollinators.
ContributorsBurden, Christina Marie (Author) / Amdam, Gro (Thesis advisor) / Smith, Brian H. (Thesis advisor) / Gallitano-Mendel, Amelia (Committee member) / Harrison, Jon (Committee member) / Vu, Eric (Committee member) / Arizona State University (Publisher)
Created2016
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Description

Cyanidioschyzon merolae, a unicellular extremophilic red algae, is found in hot, acidic groundwater with high concentrations of heavy metals. The association makes it an ideal species to investigate mechanisms of heavy metal tolerance, which may lead to its use in phyco- remediation wherein photosynthetic algae use biological processes to bind

Cyanidioschyzon merolae, a unicellular extremophilic red algae, is found in hot, acidic groundwater with high concentrations of heavy metals. The association makes it an ideal species to investigate mechanisms of heavy metal tolerance, which may lead to its use in phyco- remediation wherein photosynthetic algae use biological processes to bind and remove toxic substances. Two strains of C. merolae, MS1 and 10D, are genetically very similar, despite the latter lacking a cell wall. To investigate heavy metal toxicity and the role of the cell wall, the two strains of C. merolae were exposed to various concentrations of cadmium and cultures were evaluated spectrophotometrically to assess the impact on growth over a 7-day period. The IC50 values of MS1 and 10D were estimated to be 15 and 0.5 ppm CdCl2 respectively, indicating that the cell wall provides protection under the presence of heavy metals. Cadmium uptake was also measured using Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES) to investigate metal ion exclusion and acidocalcisome-Cd2+ chelation as potential tolerance mechanisms. ICP-OES data indicated that 10D inoculum pretreated with phosphate depletion and re-supplementation, to induce Cd chelation in acidocalcisomes, then cultured in MA2 had the highest biomass Cd content of all strains and treatments (0.321 ppm; 31.55%). The cell wall clearly promotes survival and resistance to higher concentrations of environmental heavy metals, however, neither MS1 nor 10D seemed to be strains primed for phyco-remediation of heavy metal contamination through cellular uptake and sequestration.

ContributorsIsachsen, Iona (Author) / Lammers, Peter (Thesis director) / Seger, Mark (Committee member) / Lauersen, Kyle (Committee member) / Barrett, The Honors College (Contributor) / School of Life Sciences (Contributor) / School of Sustainability (Contributor)
Created2022-05