Expression analysis of a FLP-3 translational fusion (
pflp-3::flp- 3::mCherry) confirmed previous expression analyses of the neuropeptide within male-specific spicule neurons. Transcriptional reporters have shown robust
flp-3 expression in the amphid IL1 neurons, as well as the sensory PQR and the male-specific interneuron, CP9, although our translational fusion exhibited no PQR or CP9 expression. Previous studies employed 1-2kb regions of promoter sequence driving GFP expression,while our construct employs a 4 kb region, thereby incorporating further regulatory elements that may restrict expression patterns. By including the full coding sequence in our translational fusion, we have also incorporated the regulatory elements found within the introns of the
flp-3 gene.Interestingly, we observed localization of mCherry within sensory cilia of male dorsal and ventral IL1 neurons, as well as in puncta spanning their dendrites, consistent with peptide packing into dense core vesicles. Previous studies have observed dense core vesicles within, and being released from, dendritic arbors, supporting our findings that FLP-3 is packaged within the dendrites of the IL1 neurons. We found an identical expression pattern within the IL1 cilia and dendritic puncta of hermaphrodites as well. In males, our
flp-3 construct also exhibited male-specific tail expression in the SPD spicule neurons.