Differential Expression of Major Royal Jelly Proteins in the Hypopharyngeal Glands of the Honeybee upon Bacterial Ingestion.

Honeybee vitellogenin (Vg) transports pathogen fragments from the gut to the hypopharyngeal glands and is also used by nurse bees to synthesize royal jelly (RJ), which serves as a vehicle for transferring pathogen fragments to the queen and young larvae. The proteomic profile of RJ from bacterial-challenged and control colonies was compared using mass spectrometry; however, the expression changes of major royal jelly proteins (MRJPs) in hypopharyngeal glands of the honeybee in response to bacterial ingestion is not well-characterized. In this study, we investigated the expression patterns of in the fat body and in the hypopharyngeal glands of nurse bees after feeding them live or heat-killed . The expression levels of and in the hypopharyngeal glands were upregulated along with in the fat body of nurse bees fed with live or heat-killed over 12 h or 24 h. We observed that the expression patterns of and in the hypopharyngeal glands and in the fat body of nurse bees upon bacterial ingestion were differentially expressed depending on the bacterial status and the time since bacterial ingestion. In addition, the genes had increased expression in young larvae fed heat-killed . Thus, our findings indicate that bacterial ingestion upregulates the transcriptional expression of in the hypopharyngeal glands as well as in the fat body of nurse bees.