Many environmental assaults damage DNA—an organism’s genetic identity—but mechanisms have evolved to repair this damage. Oxidative damage, induced by reactive oxygen species such as hydrogen peroxide, is an example of these assaults. The consequences of DNA damaging agents are directly related to the cell’s ability to appropriately respond to and repair DNA damage (Sobol et al 2002), using pathways appropriate to each type of damage. But these processes can’t be initiated without the expression of genes coding for the repair enzymes. These processes have yet to be fully studied for ciliated protozoa, single-celled eukaryotes, but a few studies exist for Tetrahymena thermophila, using several damage mechanisms. These studies have confirmed that a number of repair genes known from other model systems are also induced in ciliates (Smith et al 2004). But these studies have been limited to candidate genes—homologs to repair enzymes known in other systems. To look for additional genes and to provide complementary data sets, several species of the related ciliate Paramecium, including Paramecium caudatum and Paramecium tetraurelia, were examined for their responses to oxidative damage, using protocols published on the treatments of Tetrahymena. Paramecium were treated to .3% hydrogen peroxide (after verifying that the Tetrahymena dose was appropriate for Paramecium) and RNA were collected after zero, one, two, three and four hours. The next stage is to turn these RNAs into next generation sequencing RNAseq libraries. After these libraries are sequenced at the IU Center for Genomics and Bioinformatics (CGG), I will examine the levels of mRNA transcripts produced for each gene after DNA damage, compared to its normal level of expression. Based on this comparison I should be able to determine which genes are expressed at higher levels after DNA damage. I expect to see a high level of mRNA transcripts for known repair genes, such as those known to be associated with DNA repair in Tetrahymena thermophila. However, it is also possible that I might discover genes that are not yet known to be associated with DNA repair, unique to ciliates.