GENETIC DISSECTION OF THE LEARNING MEMORY GENE DUNCE OF DROSOPHILA-MELANOGASTER

The dunce (dnc) gene of Drosophila melanogaster codes for cAMP phospho diesterase (PDE) and is required for normal learning/memory and for fe male fertility. The expression of the gene is elevated in mushroom bod ies, brain structures implicated in olfactory learning and memory. In this study several chromosomal deletions and inversions that remove in creasingly larger portions of the dnc gene from its 5' end and progres sively more of the five known transcription start sites (tss) were use d to assess the functions of the various transcriptional units. Surpri singly, the dnc PDE activity, female fertility, mushroom body expressi on, learning, and memory were unaffected by the removal of tss1 and ts s2. tss3 was required for elevated mushroom body expression but not fo r female fertility nor initial learning. tss4 contributed to learning and the female fertility function, whereas tss5 contributed to female fertility. The results indicate that the structural complexity of the gene is of biological significance, with individual transcriptional un its serving different biological functions.