Fig. 6. MRP-1 needs to be expressed in multiple tissues for the wild-type phenotype. Functional mrp-1::GFP fusion genes driven by various tissue-specific promoters (myo-2 promoter for pharyngeal muscles, ges-1 promoter for intestinal cells, and H20 promoter for neurons) were introduced either separately or in combination into unc-31(e169);mrp-1(ut153) double mutant animals. The results show that expression in multiple tissues is necessary to rescue the abnormality of dauer larva formation efficiently. The means of two to eight lines are shown (19-92 animals/line). Because the expression in neurons and intestinal cells looked weaker than in pharyngeal cells, we increased the concentration of the former two DNA constructs by 4-fold (40 ng/µl). However, expression in one tissue still resulted in partial rescue. Animals carrying an extrachromosomal array of transgenes segregated those that had lost the extrachromosomal array. Dauer formation of these animals was also examined and is shown as a control on the left of each data set.