Targeted Ablation of the Akh Expressing Neuroendocrine Cells in the Corpora Cardiaca Renders Resistance to Starvation in Drosophila melanogaster. G. Lee , J.H. Park. Dept of BCMB, University of Tennessee, Knoxville, TN.

   Adipokinetic hormones (AKHs) are metabolic neuropeptides for their lipogenic and hypertrehalosemic properties, thereby providing energy substrates for the insect body such as locusts and cockroaches. Previously, Drosophila Akh gene was cloned and its genomic and peptide structures as well as its expression in the larval corpora cardiaca (CC) were characterized (Noyes et al., 1995). To understand Akh gene's functions in Drosophila, we identified 5' upstream regulatory region of the Akh gene (Akh promoter) that renders reporter gene (lacZ) expression exclusively in ~14 neurosecretory cells in the larval and adult CC. By tracing axonal projections emanating from these AKHergic neurons, a few target tissues such as crop and brain were found. Our study also showed that transgenic flies bearing targeted ablation of AKHergic neurons in the adult CC using a gal4/UAS system displayed remarkably strong resistance to starvation-induced death; AKH-knockout flies survived ~24 hours longer than control or wild-type flies. Close examination of individual locomotor activity pattern revealed that starved wild-type flies displayed prolonged hyper-mobility prior to their death, whereas AKH-knockouts rather progressively became hypoactive. It suggests that starvation resistance of AKH-knockout flies might be resulted from slower depletion of energy source due to their inability to induce bouts of hyperactivity under the starvation condition.