Fig. 2. pig-1 ced-3 and ham-1 HSN and PHB phenotypes. (A) pig-1 mutants have extra phasmid (PHA or PHB) neurons and extra HSNs. Mutations in pig-1 interact synergistically with mutations in ced-3 to control the penetrance of extra neurons. The number of PHA/Bs was scored using the integrated reporter gmIs12 [srb-6::gfp], and the number of HSNs was scored by immunostaining with an anti-serotonin antiserum. (B) The extra phasmid neurons in pig-1 mutants are PHBs. The numbers of PHA and PHB neurons were determined using the reporters gmIs22[nlp-1::gfp] and ynIs45[flp-15::gfp], respectively. (C) Mutations in pig-1 are epistatic to ham-1. (D) pig-1 is epistatic to ham-1 in a ced-3 background. (C,D) The numbers of HSNs and PHBs were scored as described in A. For all genotypes, the number of lineages scored is shown below the histogram in parentheses.