Impact of light and alarm pheromone on immediate early gene expression in the European honeybee, Apis mellifera

Immediate early genes (IEGs) are a group of rapidly and transiently expressed genes that are induced by cellular stimulation, such as neuronal activation, and do not rely on de novo protein synthesis. Based on these characteristics, IEGs are used as markers for localizing neuronal activation in vertebrate brains. However, whether their orthologs in insects are functioning in a similar way is still an open question. We report findings on the expression profiles of two IEGs in honeybee workers, encoding the honeybee orthologs of the vertebrate transcription factors Egr and c-Jun, after exposure to light and alarm pheromone. While Amjra, the c-jun ortholog, becomes upregulated in various brain parts following stimulation with either stimulus, the expression of the X1 isoform of Amegr, the egr ortholog, is not affected. These findings suggest different roles and molecular pathways for both IEGs within the neuronal network of the honeybee and provide first data on an isoform-specific analysis of Amegr expression.