This experiment investigates the genetic architecture of gene expression (eQTL) in three different treatments in an N2xCB4856 introgression line population of Caenorhabditis elegans. The goal is to compare the effect of small CB4856 introgressions in an N2 genetic background versus a previously conducted experiment using recombinant inbred lines (RILs) derived from the same parental strains. We exposed ILs to a control (56 ILs), heat-stress (56 ILs), and recovery treatment (55 ILs). Additionally, also both parental strains, N2 and CB4856 were exposed to these three treatments (in at least 3 replicas per treatment). More specifically, these three conditions can be characterized as: (i) the control treatment was grown for 48 hours at 20C, (ii) the heat-stress treatment was grown for 46 hours at 20C followed by 2 hours at 35C, and (iii) the recovery treatment was grown for 46 hours at 20C, followed by 2 hours at 35C and thereafter 2 hours at 20C. Thereafter RNA was isolated, labelled and hybridized on microarray. The gene expression profiles were used for comparison versus findings in the RIL population (E-MTAB-5779).