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2014 Research Showcase
PMB Abstracts
Abstract Title : Circadian regulation of metabolism under diurnal cycles in cyanobacteria
Abstract : Circadian rhythms are of major biological importance to most organisms and are important for proper timing of cellular events in coordination with daily light-dark changes. The photosynthetic cyanobacterium Synechococcus elongatus is a model organism for the circadian clock. Currently, there is interest in photosynthetic organisms to produce biofuel, pharmaceutical products, and industrial chemicals. On an industrial scale, photosynthetic organisms are grown outdoors, which are subject to light-dark cycles that impact product yields through alterations in metabolism. Experiments have not been conducted on how the clock regulates glycogen − an energy storage molecule − in these organisms and how environmental cycles integrate with clock control. Glycogen degradation is important for night-time survival and glycogen content is regulated by the circadian clock. The transcriptional regulator RpaA is the primary output from the S. elongatus circadian clock and has over 170 gene targets. Mutants in rpaA display poor glycogen degradation at night and are sensitive to light-dark cycles. We hypothesize that these phenotypes are due to the rpaA mutant?s mis-regulation of glycogen metabolic genes, rather than a direct effect of the lack of RpaA protein. To test this hypothesis we have cloned genes that are known RpaA transcriptional targets, have decreased expression in an rpaA mutant, and are important in glycogen metabolism. We expressed these genes in an rpaA mutant background using the highly expressed psbAI promoter. Elucidating how the circadian clock controls glycogen metabolism in environmentally relevant light-dark cycles is important if we are to optimize biomolecule production on a mass scale.
Abstract Title : Identification of Gene Effect on Seed Size Phenotype by Screening tDNA Knockouts
Abstract : Seed size is an important trait in plants. The components of the seed aid in proper seed germination and sustain the embryo during early development. Factors that determine final seed size are those that affect endosperm and embryo. Arabidopisis thaliana has been used as a model plant for many years and the the Genomic Analysis Laboratory (GAL) at the Salk Institute has made a library of over ~45,000 tDNA gene-knockouts that account for 98% of its genome. Using this library we were able to screen for genes affecting the seed size.
Abstract Title : An Automated Approach Toward Identifying Transpiration Phenotypes of Mutant Arabidopsis thaliana Lines
Abstract : Abscisic acid (ABA) is a plant hormone that limits transpiration water loss by reducing the aperture of stomatal pores in leaves. The conventional method used to study ABA signaling pathways relies upon direct measuring of stomatal apertures, but this method is inefficient. I am developing an alternative method that employs a robot to streamline the measurement of transpiration rates. By utilizing liquid growth media, different test conditions are quickly established via chemical solutions. This project will focus on combining ABA with the automated system to classify novel mutant lines.