Finally, imaging experiments performed in dissected larvae of D. melanogaster demonstrated NRB-AF12 adaptability in complex biological systems. The live imaging of fly tissues showed that NRB-AF12 maintain the same subcellular distribution of ER-Tr also in vivo, supporting the theory of a common target. Moreover, we observed a significant signal in the Drosophila tracheal system where Drosophila Sur (Dsur) is highly expressed (Nasonkin et al., 1999). Dsur, encodes a glibenclamide-sensitive potassium channel and has been identified as the functional orthologue of the mammalian SUR2 (Kim and Rulifson, 2004). On the basis of these favorable properties, we propose NRB-AF12 as an alternative fluorescent dye to ER-Tr, and a new improved tool for labeling intracellular organelles.