CHANGE IN THE MODE OF GENE-EXPRESSION OF THE HYPOPHARYNGEAL GLAND-CELLS WITH AN AGE-DEPENDENT ROLE CHANGE OF THE WORKER HONEYBEE APIS-MELLIFERA L

Major proteins synthesized in the hypopharyngeal gland of the worker h oneybee change from bee-milk proteins to alpha-glucosidase in accordan ce with the age-dependent role change of the worker bee. Previously, w e showed that the gene for alpha-glucosidase is expressed specifically in the forager-bee gland [Ohashi, K., Sawata, M., Takeuchi, H., Nator i, S. & Kubo, T. (1996) Biochem. Biophys. Res. Commun. 221, 380-385]. Here, we describe the isolation and analysis of cDNAs for two bee-milk 56-kDa and 64-kDa proteins. The 56-kDa protein was a glycoprotein whi ch shared 63.2% and 56.9% amino acid sequence identities with proteins encoded by cDNA for royal-jelly-related protein 57-1 (pRJP57-1) and p RJP57-2. The 64-kDa protein cDNA was identical to pRJP57-1. Thus, thes e bee-milk proteins seem to form a structurally related protein family . The gene for the 64-kDa protein/RJP57-1 was expressed specifically i n the nurse-bee gland, whereas that for the 56-kDa protein was express ed in both the nurse-bee and forager-bee glands. mRNAs for the 56-kDa and 64-kDa proteins were detected by in situ hybridization in a whole acinus of the nurse-bee gland, whereas mRNAs for the 56-kDa protein an d cc-glucosidase were detected in that of the forager-bee gland. There fore, the individual secretory cells of the acinus of the hypopharynge al gland were shown to express these genes differently with the age-de pendent role change of the worker bee.