Toxicogenomic responses of PCB52 in the nematode Caenorhabditis elegans

Although non-coplanar PCBs are ubiquitous organic chemicals known to induce numerous biological responses and thus are toxic to man and wildlife, little is known about the toxic mode of action. Using PCB52, an ortho-substituted, 2,2’,5,5’-tetrachlorobiphenyl, it was possible to pinpoint the relationship between induced gene expression and observed toxicity in the model nematode Caenorhabditis elegans. Keywords: stress response Based on the calculated EC20 for brood size (5 mg/L), whole genome DNA microarray experiments were performed using a common reference design to identify differentially expressed genes. Gene knockdown by RNAi was used to determine the consequences in reproductive fitness in the presence and absence of PCB52. Each of the 2x4 “biological replicates” consists of two technical repeats. Each technical repeat has a cy5 value (sample) and a cy3 value (reference sample). The value for each technical repeat is calculated as a ratio and the normalized data is the mean between the ratio of the two technical repeats.