Overview
- Using synthetic diets each lacking one essential amino acid, researchers sequenced RNA from fly heads across 11 conditions to chart state-dependent gene expression.
- Two olfactory receptor genes, Or92a and Ir76a, were consistently upregulated across deprivations, indicating a shared program that tunes sensory detection.
- Or92a mediates detection of diacetyl from fermenting yeast, and flies without Or92a or given diacetyl‑deficient yeast located food but fed less.
- Ir76a responds to a bacterial metabolite (PEA) produced by Lactobacillus and Acetobacter, and amino‑acid‑deprived flies selectively fed on live, metabolically active bacteria.
- Loss of Ir76a abolished bacteria feeding, linking transcriptional reprogramming to microbe‑seeking behavior, with suggested human parallels to fermented‑food attraction remaining speculative.