Fig. 4. Interference with spg-7 (predicted to encode a mitochondrial protease) or ethidium bromide treatment perturbs protein processing in the mitochondria and activate the endogenous hsp-6 gene. (A) Immunoblot of GFP in detergent extracts from transgenic animals expressing conventional GFP (a cytoplasmic protein) or GFP with an N-terminal mitochondrial import sequence (mtGFP), both in the body wall muscle. The animals were exposed to mock RNAi or spg-1(RNAi) or cultured on 125 µg/ml ethidium bromide (EtBr) as indicated. Equal fractions of the total extract (Total), 100,000 g soluble (Soluble) and 100,000 g pellet fractions (Pellet) of the whole animal detergent extract were loaded on the gel as indicated. (B) Autoradiogram of a northern blot of total RNA from mock-RNAi, spg-7(RNAi) or ethidium bromide (EtBr) treated animals. The blot was hybridized sequentially to radiolabeled fragments from the hsp-6, spg-7, aco-2, cts-1, F1F0 ATP synthase -chain (F1F0) and cytochrome c oxidase subunit IV (Cyt C Ox IV) genes. (C) Quantification of the radiolabeled signal on the blots shown in B. The hybridization signal for each gene at the untreated point was set as 1.