Intestinal control of feeding initiation in Drosophila melanogaster

The interplay between feeding and excretion is essential for organismal nutrition and survival, yet their mechanistic coupling remains poorly understood. At the onset of life, feeding must be initiated while developmental waste products - the meconium - need to be eliminated. Using Drosophila as a model system, we explored the in vivo mechanisms coordinating these processes. We developed novel behavioral assays for newly eclosed flies and discovered that, similar to neonatal mammals, Drosophila excrete their meconium shortly after eclosion. Remarkably, feeding initiation occurs only after partial meconium elimination. We identified a cis-regulatory element associated with the apterous gene, which, when disrupted, prevents both meconium excretion and adult feeding initiation. These flies develop hindgut obstruction (ileus), avoid food, and exhibit increased proboscis extension sleep - a behaviour we found plays a functional role in waste clearance under normal conditions. Through experimental inhibition of meconium excretion, we established that this process is prerequisite for feeding initiation, suggesting a gut-to-brain signaling circuit that couples these fundamental physiological processes. The progression of phenotypes we observed parallels the hallmarks of mechanical ileus in humans. Our findings reveal previously unrecognized links between intestinal clearance, feeding behavior, and survival, with potential implications for understanding similar processes across species.