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Seminar Details

The social clock of the bee

Date

11/04/2019

Lecturers

Prof. Guy Bloch - Dept. of Ecology, Evolution and Behavior, The Hebrew University of Jerusalem

Abstract

Internal clocks driving rhythms of about a day (circadian) are ubiquitous in animals, allowing them to anticipate changes in their environment. Studies with humans and lab animals further show that genetic or environmental disturbances to circadian clocks, or the rhythms they produce, are commonly associated with illness, compromised performance, or reduced survival. Nevertheless, some animals including Arctic mammals, open sea fish, and migrating birds, are active around-the-clock with no apparent ill effects. The mechanisms allowing this remarkable natural plasticity are unknown. In social insects such as honeybees, plasticity in circadian rhythms is associated with the division of labor and thus thought to be functionally significance. Forager bees show strong circadian rhythms that are used for sun-compass navigation and timing visits to flowers whereas “nurse” bees tend brood around-the-clock with no, or only weak, circadian rhythms. We generated and validated a new and specific antibody against the clock protein PERIOD of the honeybee Apis mellifera(amPER), and used it to characterize the circadian network in the honeybee brain. We found many similarities to Drosophila melanogaster and other insects, suggesting common anatomical organization principles in the insect clock that have not been appreciated before. Time course analyses revealed strong daily oscillations in amPER levels in foragers, which show circadian rhythms, and also in nurses that do not, although the latter have attenuated oscillations in whole brain mRNA clock gene levels. The clock of around-the-clock active nurses is entrained by the hive environment, and this “social entrainment” can override photic entrainment, which is typically considered to be the stronger environmental signal resetting the clock. The oscillations in nurses show that activity can be uncoupled from the circadian network and support the hypothesis that a ticking circadian clock is essential even in around-the-clock active animals in a constant physical environment.

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