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Faculty Sponsor

Dr. Tanya Soule


Department of Biology

University Affiliation

Indiana University – Purdue University Fort Wayne


Some cyanobacteria produce extracellular polymeric substances (EPS) which form a slime layer around the cells to protect them from environmental hazards. Furthermore, some cyanobacteria are also known for being able to produce a biological sunscreen called scytonemin that is deposited within the EPS. This sunscreen is a lipid-soluble indole-alkaloid pigment that is induced by and absorbs long-wavelength UV radiation (UVA). The model cyanobacterium Nostoc punctiforme ATCC 29133 produces EPS and accumulates scytonemin in response to UVA. Previous research in our lab found that when exposed to UVA, the wild type N. punctiforme had similar levels of EPS as the non-UVA controls. This is in contrast to the scytonemin-deficient mutant strain (SCY59) which had a significant increase in EPS when exposed to UVA. Since the genes associated with EPS in N. punctiforme have only been identified through comparative genomics, it was of interest to use this system for inducing EPS to initially characterize these putative EPS-associated genes. For this, a series of putative EPS-associated genes (homologs of wza, wzb, wzc, wzx, and wzy genes) in the wild type and SCY59 were assayed for gene expression changes following UVA stress. Initial experiments did not result in a change in expression for the first set of gene homologs assayed for 24 hrs of stress. Additional experiments are being performed on additional homologs of these genes with varying time points in an effort to capture any change in expression. Once the putative genes are initially identified as responsive, and likely functional, through gene expression they will be targeted in the generation of knock-out mutants.


Biology | Life Sciences

Measuring the Expression of Genes Associated with Extracellular Polymeric Substances in Nostoc Punctiforme

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