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        Oxidative stress is caused by free radicals in the cell.  Free radicals include superoxide anions, hydroxyl radicals, and hydrogen peroxide.  These free radicals are created in cells as a by-product of aerobic respiration and can damage many cellular components including lipids, proteins, and nucleic acids.¹  In humans, the damage could lead to diseases such as cancer, heart disease, and neurodegenerative diseases like Parkinson’s and Alzheimer’s.² 

Saccharomyces cerevisiae is a great model organism to study oxidative stress.  S. cerevisiae is a single celled eukaryote containing anti-oxidant genes found in all other eukaryotes.  It is easily obtained and the genome can be easily manipulated.  The ability to manipulate the genome provides researchers powerful tools to investigate the cellular pathways involved in oxidative stress.²

            Eukaryotic cells possess several metabolic pathways to reduce free radicals and decrease the damage caused by oxidative stress.  One such pathway utilizes Glucose 6-phosphate dehydrogenase (G6PDH).  G6PDH is encoded by ZMF 1 and catalyzes the reduction of NADP to NADPH.³  NADPH is essential for maintaining reduced glutathione, an electron donor and antioxidant, in the cells.  This provides protection against oxidative stress.  Disrupting the ZMF 1 gene or its product (G6PDH) results in a phenotypic susceptibility to oxidative stress: hydrogen peroxide susceptibility and methionine auxotrophy.²  Other research has shown that ZMS1 is important for respiratory growth when S. cerevisiae uses a glycerol based carbon source.⁴  However, over expression of ZMS1 or ZMS2 can suppress ZMF1 mutations.²  Additionally, ZMF 1 knockout yeast with either a zms1 or zms2 overexpression (but not both) exhibit growth comparable to wildtype S. cerevisiae.  Sequence analysis of ZMS1 and ZMS2 reveals that each might produce a product with a zinc finger domain.²  This suggests that ZMS1 and ZMS2 might be transcription factors.

    RNA microarrays are a powerful technique to identify unregulated and down regulated genes in a particular sample.  Our research will use microarrays to investigate how RNA expression in ∆zms1 differs from wildtype S. cerevisiae.  Over expression of ZMS1 suppresses zmf1 mutations, which are characterized by a phenotype sensitive to oxidative stress; therefore, identifying the genes differentially expressed by ∆zms1 could provide insight into other pathways that combat oxidative stress.  To simplify research, we will be looking at grids 5 and 6 from slides 13760694, 13760722, and 13760724.  We hypothesize that the zms1 knockouts will display up-regulation in various other genes to combat the oxidative stress.