To further confirm that RNAi by feeding is comparable in effectiveness to injection for analyzing maternal-effect genes, we made four-dimensional time-lapse video recordings of developing embryos whose mothers were fed with dsRNA corresponding to the 10 above genes with a mutant phenotype detectable by the third cell division (gpb-1, par-1, par-2, par-3, par-6, cyk-1, dnc-1, bir-1, plk-1, and dhc-1,). In each case, the known null phenotypes were obtained (Figure 3, and data not shown; for cyk-1, one of two embryos recorded had the known phenotype and the other survived). For example, par-2(RNAi) by either method yielded spindle orientation defects, and bir-1(RNAi) by either method yielded embryos with cytokinesis defects (Figure 3) [19,20].
