Amfor expression in the honeybee brain: a trigger mechanism for nurse-forager transition

The honeybee's colony fitness relies on an optimized age-dependent division of labor. Transition from nursing activities to foraging activities is associated with an increase in the expression of the Amfor gene. Ben-Shahar et al. [Ben-Shahar, Y., Robichon, A., Sokolowski, M.B., Robinson, G.E., 2002. Influence of gene action across different time scales on behavior. Science 296, 741-744] showed that the Amfor transcripts and their gene products are involved in regulating the transition from one task to the next. In this study, we investigated the trajectory of the expression of this gene in the brain over time. The expression pattern could contribute to our understanding of the involvement of Amfor in the transition process. Is there a gradual increase in transcript or a peak in expression triggering a downstream path of multiple differential gene expression? Hereto, bees were sampled from colonies containing marked 1-day-old bees every 2 or 3 days around the expected time of transition from nurse to forager, from day 13 to 25. To quantify Amfor transcript in the brain, we developed a real-time RT-PCR assay, based on Taqman technology, using fluorescent probes. Results revealed a trigger mechanism rather than a continued elevation of Amfor expression. The appearance of an Amfor expression peak suggests that under normal physiological conditions foraging behavior is, at least in part, due to a trigger-effect of Amfor.