sft-1 or oxa-1 RNAi results in reduced gene expression, COX staining and brood size. A: RT-PCR of oxa-1 and sft-1 to compare mRNA levels. Lane 1, 50 bp DNA ladder. Upper panel: Lane 2, RT-PCR products from WT animals. Upper band (350 bp) corresponds to eft-2 mRNA (internal control), lower band (220 bp) corresponds to sft-1 mRNA. Lane 3, RT-PCR products from the progeny of animals injected with sft-1 dsRNA. sft-1 expression is greatly reduced. Lower panel: Lane 2, RT-PCR products from WT animals. Upper band (350 bp) corresponds to the eft-2 internal control, lower band (164 bp) corresponds to oxa-1 mRNA. Lane 3, RT-PCR products from the progeny of animals injected with oxa-1 dsRNA. oxa-1 expression is greatly reduced. B: COX staining in WT and sft-1(RNAi) animals. In WT, COX staining is particularly prevalent in the pharynx (black arrowhead) and germ line (black arrow), tissues that have high energy demands. In sft-1(RNAi) animals, COX staining is greatly reduced (photomicrographs taken using identical exposure times), especially in the germ line (dotted arrow). Scale bar, 100 μm. C: Brood size of WT animals injected with sft-1 or oxa-1 dsRNA compared with control animals injected with TE only (labeled N2). Both sft-1 and oxa-1 RNAi result in a significantly reduced brood size compared with controls (*P <0.005). The darker shaded area of the bar corresponding to oxa-1(RNAi) represents the proportion of dead embryos. Error bars denote the standard error of the mean (SEM). D: Embryonic lethality induced by oxa-1 RNAi. Left hand panel: oxa-1(RNAi) embryos, right hand panel: WT embryos at equivalent stages. Defects can be seen throughout embryogenesis, including necrotic regions in early embryos (i, white arrowhead), morphological defects at the “bean” stage (ii), elongation defects at the “comma” stage (iii) and later (iv, v). Posterior defects are particularly pronounced.