Expression analysis of the lingerer gene in the larval central nervous system of Drosophila melanogaster

The lingerer (lig) gene is necessary for initiation and termination of copulatory behavior in Drosophila melanogaster. The lig gene encodes cytoplasmic proteins, and is expressed in the central nervous system (CNS) during the late third-instar larval stage when the lig function is required for normal copulation to occur after adult eclosion. To characterize the lig-expressing cells in the late third-instar larval CNS, we have isolated a genomic fragment containing the promoter/enhancer region of the lig gene, and established transgenic lines in which expression of reporter genes is controlled by the lig promoter/enhancer. In the larval brain, reporter genes were expressed in all of the glial cells and in clusters of neurons that projected contralaterally. In the larval ventral ganglion, reporter genes were expressed in subperineurial glia, peripheral exit glia, and a number of interneurons, but not in motor neurons. In the cloned promoter/enhancer region, we have found the sequence motif for binding of the REPO protein, a transcription factor essential for the differentiation and maintenance of glial cells. The lig gene is thus one of the candidate target genes for the REPO transcription factor.