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CRISPR/Cas technology is increasingly being used as a common methodology in many cancer biology studies due to the ease and convenience of the technique. Precise editing of genomic DNA has been achieved upon repair of CRISPR-induced DNA double-strand breaks (DSBs) by homologous recombination (HR). HR repairs DNA DSBs with high fidelity and therefore, deficiencies in HR result in genome instability. These deficiencies have been demonstrated in many cancers. RAD51-dependent HR is a very important pathway for repairing DSBs. Previous studies have shown that genome editing using CRISPR technology relies on the repair of site-specific DNA DSBs induced by the RNA-guided Cas9 endonuclease. Furthermore, previous studies have shown that the efficiency of CRISPR-mediated HR can be improved by the stimulation of HR promoting factors, such as the RAD51 recombinase. Despite the ease and efficient use the CRISPR/Cas technology for genome editing, one limitation is the potential occurrence of associated off-target effects. If CRISPR technology is planned to be used to target cancer cells with defective HR capabilities, will off-target mutations be likely to occur? In order to answer this question, a system was developed in Saccharomyces cerevisiae using green fluorescent protein (GFP) as a reporter to identify off-target CRISPR-induced DSBs. This study set out to test the number of off-target DSBs that could be introduced by CRISPR-induced genome editing in a RAD51-deficient HR model. We were curious whether loss of RAD51-dependent HR would increase the abundance of off-target CRISPR-induced DSBs in mutant yeast strains as compared to those with a functioning HR-dependent DNA repair pathway. Preliminary findings using this system will be presented. 

Research over the last decade has revealed the importance of the cutaneous microbiome for the health and immune function of amphibians. Thousands of Bacteria and Archaeans species living in and on the skin are able to outcompete pathogenic species of fungus or types of viruses. The relationship between microbes and their host is so intimate that the term "metaorganism" has been used to describe this phenomenon. We are, however, at the early stages of understanding what determines the composition of the cutaneous microbiome and the relative effects of factors like genetics and habitat use. Could it be that there is a species-specific “microbiome fingerprint” that is consistent across different sites? Do species inhabiting similar microhabitats host similar microbes? We have replicated a similar study performed in Sosbee Cove in Union County, with a site in Cherokee County, with multiple species that are comparable across the two sites. We present our project designed to answer these questions and report preliminary results. 

Abstract Captive breeding has become a critical tool for the restoration of amphibian populations decimated by diseases. However, much is unknown about effects of long-term captivity on amphibian health and particularly immune system function. Therefore, we have begun a project to understand the effects of captivity and captive breeding on the cutaneous microbiome of lungless salamanders. The community of microbes living in and on the skin of lungless salamanders (Plethodontidae) is an important predictor of the organisms’ ability to ward off diseases like chytridiomycosis. We compare the microbiome of wild and long-term (8 years) captive or captive-bred Ocoee and Blue Ridge two-lined salamanders (Desmognathus ocoee and Eurycea wilderae, respectively) all from the Charles H. Wharton Conservation Center in Union County, GA. Microbiome communities were estimated by amplifying the V4 region of the 16S rDNA gene and then comparing with sequences from the Greengenes database. We present our study design and preliminary results.