Identification and characterization of an Egr ortholog as a neural immediate early gene in the European honeybee (Apis mellifera L.)

To date, there are only few reports of immediate early genes (IEGs) available in insects. Aiming at identifying a conserved IEG in insects, we characterized an Egr homolog of the honeybee (AmEgr: Apis mellifera Egr). AmEgr was transiently induced in whole worker brains after seizure induction. In situ hybridization for AmEgr indicated that neural activity of a certain mushroom body (a higher brain center) neuron subtype, which is the same as that we previously identified using another non-coding IEG, termed kakusei, is more enhanced in forager brains. These findings suggest that Egr can be utilized as an IEG in insects.