Reduced expression of major royal jelly protein 1 gene in the mushroom bodies of worker honeybees with reduced learning ability

The learning ability of European honeybees, Apis mellifera, develops with age. However, when worker bees are isolated from their colony and are fed only sucrose solution, their learning development is hindered. This rearing method has allowed us to compare worker bees of the same age but with different learning abilities. In this study, we examined the influence of this rearing condition on gene expression in the mushroom body, which is the insect brain center involved in learning and memory. A differential display experiment comparing worker bees maintained in a hive with those reared in isolation showed that the expression of the major royal jelly protein (mrjp) 1 gene was reduced in the isolated worker bees. MRJP1 is synthesized in the hypopharyngeal gland and serves a nutritional function in larval and queen food. Our results suggest that mrjp1 is also important in brain function, possibly involved in the development of learning ability.