Authors injected double-stranded
pha-4 RNA into strain JM97 to phenocopy a
pha-4 null mutation, collected the arrested (pharynx-defective) embryos, and stained for beta-galactosidase activity. From 171 embryos examined, none showed reporter gene expression (data not shown). This result is consistent with PHA-4 directly acting on the
ges-1 3'-enhancer.