The weight of royal jelly: Understanding the role of major royal jelly proteins as regulators of geotaxis

The Major Royal Jelly Proteins (mrjps) are some of the most highly expressed genes in the brains of the Western honey bee (Apis mellifera), but the role they play in behavioral traits is still poorly understood. The reduction in mrjp expression as honey bees transition from nursing to foraging tasks suggests a link between behavioral changes and mrjp gene expression, but no studies have been done to date. Here, we explore the role of mrjps in geotaxis, the ability of an organism to move in response to gravity. Using a novel UAS-mrjp system in Drosophila melanogaster we showed that two of the mrjps influence the fly’s ability to perform simple climbing tasks. To validate this result in honey bees, we developed an upscaled fly geotaxis assay. Additionally, we have performed dsRNA knock-down of the mrjps using modified Snodgrassella alvi. Results in mrjp-expressing honey bees have poor climbing abilities, matching the results we found in mrjp-expressing Drosophila. These results demonstrate that the mrjps influence geotaxis in a yet uncharacterized way and suggest that these genes may be major regulators of expression and behavior.