A nematode-specific gene underlies bleomycin-response variation in Caenorhabditis elegans

Shannon C. Brady; Stefan Zdraljevic; Karol W. Bisaga; Robyn E. Tanny; Daniel E. Cook; Daehan Lee; Ye Wang; Erik C. Andersen

Bleomycin causes double-stranded DNA breaks, which ultimately lead to cytotoxicity of rapidly 428 dividing cell populations. Therefore, exposure to bleomycin can affect the development of C. 429 elegans larvae as well as germ-cell production of adult animals. We used a high-throughput 430 assay (HTA) to measure the effects of bleomycin on development and brood size (Figure S1 , 431 Materials and Methods). To determine the concentration of bleomycin that would maximize 432 among-strain while minimizing within-strain phenotypic variation, we used the HTA to perform 433 a dose-response assay. We assessed bleomycin responses for four divergent strains (N2, 434 CB4856, JU258, and DL238) across each of 26 HTA traits (File S1, Figure S2 ). Lee et al. 2017). We used these RIAILs to identify genetic variants that contribute to differential 449 bleomycin responses between the N2 and CB4856 strains. Using our HTA, we measured each of 450 the 26 fitness parameters for 249 RIAILs (Materials and Methods, File S3). Correlations 451 between each pairwise combination of the 26 HTA measurements revealed several clusters of 452 highly correlated traits ( Figure S3) . Therefore, the summary statistics measured by the 453 BIOSORT should not be considered independent traits for linkage mapping. We selected median 454 optical density (median.EXT) for future analyses, which is related to both animal length and 455 optical extinction, because this trait was highly correlated with many of the 26 HTA traits and 456 was highly heritable (H 2 = 0.73, File S2). 457 458