set-4p::GFP transgenic animals expressed GFP broadly in embryos. Post-embryonically, we detected fluorescence predominantly in the head and tail regions of the animal, in a pattern consistent with neuronal expression. To confirm this, we established a transgenic strain that co-expressed
set-4p::GFP and mCherry driven by the pan-neuronal
rab-3 promoter (Nonet et al., 1997). At all developmental stages interrogated, we observed co-localization of green and red fluorescence, consistent with somatic
set-4p::GFP expression being predominantly neuronal. We did not observe significant GFP expression in intestine, body wall muscle, or hypodermis. The extent of co-localization of green and red fluorescence in set- 4p::GFP transgenic animals exposed to DiI reveals that the
set-4 promoter is active in amphid sensory neurons as well as in other cells.