Department of Ecology, Evolution, and Behavior, The Alexander Silberman Institute of Life Sciences, The Hebrew University of Jerusalem, Jerusalem, 91904, Israel.
J Neurosci. 2010 Sep 15;30(37):12517-25. doi: 10.1523/JNEUROSCI.1490-10.2010.
The social environment influences the circadian clock of diverse animals, but little is known about the functional significance, the specifics of the social signals, or the dynamics of socially mediated changes in the clock. Honey bees switch between activities with and without circadian rhythms according to their social task. Forager bees have strong circadian rhythms, whereas "nurse" bees typically care for the brood around-the-clock with no circadian rhythms in behavior or clock gene expression. Here we show that nurse-age bees that were restricted to a broodless comb inside or outside the hive showed robust behavioral and molecular circadian rhythms. By contrast, young nurses tended brood with no circadian rhythms in behavior or clock gene expression, even under a light-dark illumination regime or when placed with brood--but no queen--in a small cage outside the hive. This behavior is context-dependent because nurses showed circadian rhythms in locomotor activity shortly after removal from the hive, and in clock gene expression after ∼16 h. These findings suggest that direct interaction with the brood modulates the circadian system of honey bees. The dynamics of rhythm development best fit models positing that at least some pacemakers continue to oscillate and be entrained by the environment in nurses that are active around the clock. These cells set the phase to the clock network when the nurse is removed from the hive. These findings suggest that despite its robustness, the circadian system exhibits profound plasticity, enabling adjustment to rapid changes in the social environment.
社会环境会影响各种动物的生物钟，但我们对于社会信号的功能意义、具体内容，以及时钟的社交介导变化的动态了解甚少。蜜蜂会根据其社会任务在有节律和无节律的活动之间切换。觅食蜂具有很强的昼夜节律，而“护理”蜂通常会昼夜不停地照顾幼虫，其行为或生物钟基因表达没有昼夜节律。在这里，我们发现被限制在蜂巢内或外无幼虫的巢脾上的老龄护理蜂表现出强烈的行为和分子昼夜节律。相比之下，年轻的护理蜂在行为或生物钟基因表达方面往往没有昼夜节律，即使在光暗照明制度下，或者当它们与幼虫（但没有蜂王）一起被放置在蜂巢外的一个小笼子里时也是如此。这种行为是情境依赖的，因为护理蜂在从蜂巢中取出后不久就表现出了运动活动的昼夜节律，在时钟基因表达后约 16 小时也是如此。这些发现表明，直接与幼虫相互作用会调节蜜蜂的生物钟系统。节律发展的动态最符合这样的模型，即至少一些起搏器在昼夜不停地活动的护理蜂中继续振荡并被环境重新同步。当护理蜂从蜂巢中取出时，这些细胞会将相位设置到时钟网络中。这些发现表明，尽管生物钟系统具有很强的稳定性，但它表现出了深刻的可塑性，能够适应社会环境的快速变化。
