Chatterjee, Abhishek (2011-05). Connecting the Circadian Clock with Chemosensation. Doctoral Dissertation. Thesis uri icon

abstract

  • Chemoreception is a primitive sense universally employed by organisms for finding and selecting food, rejecting toxic chemicals, detecting mates and offspring, choosing sites for egg-laying, recognizing territories and avoiding predators. Chemosensory responses are frequently modulated based on the internal environment of the organism. An organism's internal environment undergoes regular changes in anticipation and in response to daily changes in its external environment, e.g., light-dark cycle. A resettable timekeeping mechanism called the circadian clock internally drives these cyclical changes with a ~24 hour period. Using electrophysiological, behavioral and molecular analyses, I tested where and how these two conserved processes, viz., the circadian timekeeping mechanism and the chemosensory pathway, intersect each other at organismal and cellular levels. The presence of autonomous peripheral oscillators in the chemosensory organs of Drosophila, prompted us to test whether chemosensory responses are under control of the circadian clock. I found that local oscillators in afferent (primary) chemosensory neurons drive rhythms in physiological and behavioral responses to attractive and aversive chemical signals. During the middle of the night, high level of G proteincoupled receptor kinase 2 (GPRK2), a clock controlled signaling molecule present in chemosensory neurons, suppresses tastant-evoked responses and promotes olfactory responses. G-protein mediated signaling was shown to be involved in generating optimal response to odorants. Multifunctional chemosensory clocks exert control on feeding and metabolism. I propose that temporal plasticity in innate behaviors should offer adaptive advantages to flies.
  • Chemoreception is a primitive sense universally employed by organisms for finding and
    selecting food, rejecting toxic chemicals, detecting mates and offspring, choosing sites
    for egg-laying, recognizing territories and avoiding predators. Chemosensory responses
    are frequently modulated based on the internal environment of the organism. An
    organism's internal environment undergoes regular changes in anticipation and in
    response to daily changes in its external environment, e.g., light-dark cycle. A resettable
    timekeeping mechanism called the circadian clock internally drives these cyclical
    changes with a ~24 hour period. Using electrophysiological, behavioral and molecular
    analyses, I tested where and how these two conserved processes, viz., the circadian
    timekeeping mechanism and the chemosensory pathway, intersect each other at
    organismal and cellular levels.
    The presence of autonomous peripheral oscillators in the chemosensory organs of
    Drosophila, prompted us to test whether chemosensory responses are under control of
    the circadian clock. I found that local oscillators in afferent (primary) chemosensory
    neurons drive rhythms in physiological and behavioral responses to attractive and
    aversive chemical signals. During the middle of the night, high level of G proteincoupled
    receptor kinase 2 (GPRK2), a clock controlled signaling molecule present in
    chemosensory neurons, suppresses tastant-evoked responses and promotes olfactory
    responses. G-protein mediated signaling was shown to be involved in generating optimal
    response to odorants. Multifunctional chemosensory clocks exert control on feeding and
    metabolism. I propose that temporal plasticity in innate behaviors should offer adaptive
    advantages to flies.

publication date

  • May 2011