Comparative neuroanatomy and genomics of hugin and pheromone biosynthesis activating neuropeptide (PBAN)

The Drosophila hugin gene encodes a prepropeptide that can potentially generate several neuropeptides. (1) The gene is expressed in 20 cells of the subesophageal ganglion (SOG) that are involved in modulating feeding behavior. (2) One of the hugin neuropeptides shares homology with mammalian neuromedin U8 (NmU8), which has been shown to regulate feeding behavior in rodents. 3,4 Recent clonal analysis indicated that each hugin expressing neuron projects to one of four main targets: the protocerebrum, the ventral nerve cord, the pharynx and the corpora cardiaca. 5 In addition all hugin neurons send short neurites to a novel region ventro-lateral to the foramen, which we suggested could be the tritocerebrum. In this short article, we discuss two specific issues brought up by these analyses. One concerns the polarity of hugin neurons. The other is an evolutionary perspective on the processing of hugin neuropeptides in light of new data from mass spectrometric and genomic analyses.