Social Signals Alter the Circadian Rhythm in a Honey Bee Model

Bees have been studied as a model system, as researchers examine how disturbances in the circadian rhythm may be influenced at the level of genome activity by an individual's social interactions.

Disruption of the day/night cycle of waking and sleeping can have serious health implications for individuals who work at night, routinely have their sleep disturbed, or even temporarily experience a sleep disturbance such as "jet lag”.

Investigators at the Hebrew University of Jerusalem (Israel) chose to work with bees, since the beehive comprises two distinct populations with respect to circadian rhythm. The normal worker or forager bees have a day/night cycle and express "clock gene” activity. Nurse bees, in contrast, work around the clock deep in the dark recesses of the hive and do not express "clock genes.”

In a paper published in the September 15, 2010, issue of the Journal of Neuroscience the investigators described experiments in which they transferred nurse bees from a regular hive to one with no queen and in which they moved worker bees into the brood area of the hive.

They found that the bees rapidly became acclimated to their new environment with the nurse bees entering the circadian day/night routine while the transferred worker bees quickly adapted to round the clock activity. This rapid adaption, with accompanying change in "clock gene” expression, was thought to be a result of signals emanating from other bees in the immediate vicinity.

"Our findings show that circadian rhythms of honey bees are altered by signals from the brood that are transferred by close or direct contact,” said senior author Dr. Guy Bloch, professor of ecology, evolution, and behavior at the Hebrew University of Jerusalem. "This flexibility in the bees' clock is striking, given that humans and most other animals studied cannot sustain long periods of around-the-clock activity without deterioration in performance and an increase in disease.”

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