Multiple alleles control polyQ aggregation in Caenorhabditis elegans. (a) Scheme of generation of Q40Bristol × DR1350 recombinant inbred lines (RILs). To ensure genetic homogeneity within each RIL, 30 to 40 generations of self-reproduction were used. (b) Number of polyQ aggregates per L4 animal of parental strains and 21 RILs. Data are mean ± SD, 17 to 23 animals/data point. Colors correspond to selected strains as indicated in supplementary material (see Additional file 2: Figure S2a). (c) Images of representative animals used in (b); insets show head regions. (d) Western blotting analysis of total Q40-YFP protein levels in extracts of L3 animals, relative to Q40Bristol. Data are mean ± SD, n = 3.