Stable transgenic lines expressing the
trx-1::gfp translational fusion always resulted in GFP expression in a single pair of amphid neurons. A detailed anatomical analysis identified the ciliated chemosensory neuron pair ASJ-left and -right (ASJL, ASJR) as the cells expressing GFP. GFP fluorescence co-localizing with the fluorescent dye DiI in only one neuron pair, the ventral-most of the fluorescent dye-filling neurons, further confirmed ASJ as the neuron type expressing
trx-1 in C. elegans. A detailed sex- and stage-specific analysis of GFP expression showed that GFP fluorescence is first detectable in both male and hermaphrodite in late 3-fold stage embryos, immediately prior to hatching.
trx-1::gfp remains expressed in ASJ neurons through all stages, including dauer, until the animal dies. To some extent (in most transgenic animals at all larval stages and in adults, but not in dauers) GFP fluorescence was also detected in the intestine, readily distinguishable from gut autofluorescence, typically in the posterior-most intestinal cells. However, since the number of intestinal cells expressing GFP varied greatly between individuals, the intestinal GFP expression pattern could be due to genetic mosaicism, given that the transgenic animals analyzed in this study carry only extrachromosomal arrays and not integrated transgenes.