Transcriptional and physiological responses of hypopharyngeal glands in honeybees (Apis mellifera L.) infected by Nosema ceranae

Abstract

Nosema ceranae infection induces energetic stress, malnutrition, and precocious foraging in Apis mellifera. This study investigated effects of N. ceranae infection on the gene expression, protein content, and enzyme activity in the hypopharyngeal gland of nurse bees. The 285 differentially expressed genes were found between N. ceranae-infected and control bees using RNA-Seq, and 279 were upregulated and 6 were downregulated in infected bees. The protein level was significantly lower in infected bees than in controls, implying protein dysmetabolism and energetic stress in infected bees. The ELISA test showed that the specific activity of amylase was significantly higher in infected bees than in controls. The elevated enzymic activities were accompanied by an increased expressed level of hemolymph juvenile hormone-binding protein-encoding gene in infected bees, suggesting the possibility of Nosema-infected nurse bees to engage in behaviors that are normally performed by foragers.