FIG 1 .

Forward genetic screen for mutants exhibiting an upregulated UPR. (A) Schematic for the forward genetic screen. The SJ4005 strain, which expresses Phsp-4::gfp and is a reporter strain for the ER UPR, was used for the screen. Mutants with high expression levels of GFP were screened from the F₁ progeny after mutagenesis. (B) Fluorescence images of five of the mutant animals and SJ4005 animals containing the reporter Phsp-4::gfp. The mutants isolated in the screen were designated AY131 to AY135. (C) Fluorescence images of one of the mutants and SJ4005 animals following RNAi against the UPR genes ire-1 and xbp-1. Animals grown on empty RNAi vector were used as the control. (D) Quantitative reverse transcription-PCR (qRT-PCR) for the ER chaperone genes hsp-4 and hsp-3 in the mutant and SJ4005 animals. The bar graphs show the means plus standard deviations (SD) (error bars) from three independent experiments. The P values for hsp-4 RNA levels in mutant strains relative to SJ4005 animals are shown as follows: P < 0.001 for AY134, P < 0.001 for AY131, P < 0.01 for AY132, P < 0.001 for AY133, and P < 0.001 for AY135. The P values for hsp-3 RNA levels in mutant strains relative to the levels in SJ4005 animals are as follows: P < 0.01 for AY134, P < 0.01 for AY131, P < 0.001 for AY132, P < 0.001 for AY133, and P < 0.001 for AY135. (E) Fluorescence images of the mutants and SJ4005 animals carrying the reporter Phsp-4::gfp during development at 20°C. The time represents the time of development from eggs at 20°C on E. coli OP50. Eggs represent the time point 0 h (F) Fluorescence images and the corresponding bright-field images of adult males of mutant and SJ4005 animals carrying the reporter Phsp-4::gfp.