A gene-driven recovery mechanism: Drosophila larvae increase feeding activity for post-stress weight recovery.

Recovery from weight loss after stress is important for all organisms, although the recovery mechanisms are not fully understood. We are working to clarify these mechanisms. Here, we recorded enhanced feeding activity of Drosophila melanogaster larvae from 2 to 4 h after heat stress at 35°C for 1 h. During the post-stress period, expression levels of sweet taste gustatory receptor genes (Grs), Gr5a, Gr43a, Gr64a, and Gr64f, were elevated, whereas bitter taste Grs, Gr66a, and Gr33a, were decreased in expression and expression of a non-typical taste receptor Gr, Gr68a, was unchanged. Similar upregulation of Gr5a and downregulation of Gr66a was recorded after cold stress at 4°C. Expression levels of tropomyosin and ATP synthase ß subunit were significantly increased in larval mouth parts around 3 to 5 h after the heat stress. We infer that up-regulation of post-stress larval feeding activity, and weight recovery, is mediated by increasing capacity for mouth part muscular movements and changes in taste sensing physiology. We propose that Drosophila larvae, and likely insects generally, express an efficient mechanism to recover from weight loss during post-stress periods.