Spatiotemporal memories in honey bees: microarray analysis of time-trained foragers

Honey bees feed on flowers, many of which produce nectar during certain restricted, but consistent, time windows in the day. Previous research has shown that honey bees have the ability to form distinct spatiotemporal memories that allow them to return repeatedly to different attractive food sources at different times of day. As a first step toward understanding the molecular basis of this striking flower fidelity, this study was designed to determine whether distinct spatiotemporal memories of a food source are associated with distinct patterns of gene expression in the brain. Different groups of foragers from the same colony were trained to collect sucrose solution from an artificial feeder at one of two different times of day, one in the morning and the other in the afternoon. Bees from both training groups were collected at both training times, thus yielding a set of bees that was undergoing stereotypical food anticipatory behavior and another set that was inactive for each collection. Microarray analysis revealed that hundreds of genes were differentially expressed in the brain based on either time of day or activity state. A subset of these genes showed unique patterns of expression for each of the spatiotemporal foraging memories. Surprisingly, some of the genes involved in the regulation of circadian rhythms, such as period and cryptochrome, appear to change in expression with activity state rather than time of day. Overall, these results indicate that distinct spatiotemporal foraging memories in honey bees are associated with distinct neurogenomic states involving genes that regulate temporal activity and genes associated with appetitive behavior