The UPR ^mt promotes mitochondrial import. (a–d) To induce UPR^mt during development, glp-1(e2141ts) mutant animals were grown at 25°C on bacteria expressing cco-1 dsRNA (a and b) or spg-7 dsRNA (c and d) from the time of hatching until the first day of adulthood (animals were treated with 1:1 mixture of bacteria containing the empty RNAi vector alone [EV] to match with the double RNAi treatment). To suppress UPR^mt, animals were treated with double RNAi (1:1 mixture of bacteria replacing EV with bacteria expressing dve-1 dsRNA [a and b] or atfs-1 dsRNA [c and d]). Control worms were grown on bacteria containing EV alone. Mitochondria were isolated from the animals at day 1 of adulthood and subjected to the import assay followed by Western blot analysis. Arrowheads, mature (imported) DHFR with the MTS cleaved off (a and c). Import efficiency was quantified by measuring the mature imported protein (arrowheads) as detected by the DHFR antibody, followed by analysis with unpaired Student’s t test (two-tailed; b and d). All graphs are presented as mean ± SD. n = 3. *, P < 0.05; **, P < 0.01. Source data are available for this figure: SourceData F2.