The Drosophila Pox neuro gene: control of male courtship behavior and fertility as revealed by a complete dissection of all enhancers.

We have dissected the entire cis-regulatory region of the Drosophila Pox neuro gene with regard to its enhancers, and have analyzed their functions by the selective addition to Pox neuro null mutant flies of one or several functions, each regulated by a complete or partial enhancer. We have identified at least 15 enhancers with an astounding complexity in arrangement and substructure that regulate Pox neuro functions required for the development of the peripheral and central nervous system and of most appendages. Many of these functions are essential for normal male courtship behavior and fertility. Two enhancers regulate the development of the penis, claspers and posterior lobes of male genitalia. Three enhancers, two of which overlap, control the development of chemosensory bristles in the labellum, legs and wings, some or all of which are required for the transmission of gustatory signals elicited by female pheromones. An additional enhancer regulates in the developing brain the connectivity of two specific neuronal clusters entrusted with processing olfactory pheromone signals from the antennal nerve. Finally, functions crucial for the ability of the male to copulate depend on an enhancer that activates Pox neuro expression in the embryonic ventral cord. In addition to these male courtship and fertility functions of Pox neuro, we have identified enhancers that regulate: (1) proper segmentation of tarsal segments in the leg disc and in homologous segments of the antennal disc; and (2) proper development of the wing hinge and hence the ability of the fly to fly.