As expected, we observed extensive GFP::TRA-1 fluorescence in multiple tissues of larval and adult hermaphrodites. Surprisingly, however, we also detected significant GFP::TRA-1 in males, confined almost exclusively to the nervous system. In L3 larval males, GFP::TRA-1 was apparent in numerous head neurons, though not in as many as seen in L3 hermaphrodites. This pattern was maintained in L4 males, but, by the time of young adulthood, far fewer neurons contained GFP::TRA-1.Using a pan-neural marker, we quantified the number of GFP::TRA-1-positive neurons in the region spanned by the pharyngeal bulbs. This revealed that
tra-1 is expressed in roughly 54 and 49 head neurons in L3 and L4 males, respec- tively, and that this number decreases to 25 in 1-day-old adult males. Using a marker for ciliated sensory neurons, we found that roughly 17 of the
tra-1-expressing neurons in this region in L3 males were of this class, and that this number decreased to 9 in 1-day-old adult males. These findings suggest that
tra-1 function in the nervous system might not be limited to hermaphrodites, and that any roles it may have in the male soma could be both cell type and stage specific.