Work Package 8 (ESR 9)

Drosophila temperature circuit

General details

UKLocation
Queen Mary University, UK

Supervisors
Prof.R. Stanewsky

ESR 9
Sanne Roessingh

Other partners involved
University of Wuerzburg (DE)
CNRS, Paris (FR)

Secondments

University of Wuerzburg for 6 months in year 1/2 – training in neuroanatomy and imaging

Objectives

  • Anatomical/functional analysis of connectivity of peripheral temperature sensors to clock neurons
  • Functional analysis or Trp channel mutants and genes involved in temperature entrainment
  • Establish imaging techniques (brainbow/GRASP) to visualize individual neuronal processes and synapses

Methods

  • Establish GRASP and brainbow techniques by month 18
  • Finish anatomical mapping and initial characterization of TRP mutants by month 24
  • Finish functional analysis of cho connections (Ca2+ imaging of clock neurons) by month 30
  • Finish functional analysis of Trp mutants/genes

Description

Temperature entrainment circuit of the Drosophila clock
Chordotonal organs (cho) are internal insect mechanoreceptors, located in legs, wings and antennae and are important for temperature input to circadian clock neurons in the Drosophila brain. It remains elusive though, how temperature changes are perceived by the cho and how this information is transmitted to the central brain. Preliminary evidence suggests that Trp cation channels are involved in temperature sensing and/or transmission. The relevant Trp channels genes will be further characterized (e.g., are they expressed in cho?) and the effects of Trp channel mutants on clock protein expression in brains will be determined. Also, it is not known if cho neurons target interneurons in the thoracic CNS or directly project to clock neurons in the brain. Moreover, it is not clear which clock neurons are targeted by the cho. We will apply novel fluorescent imaging approaches (GRASP and Brainbow) to reveal the connectivity of the temperature entrainment circuit. To functionally confirm our anatomical data, we will perform Ca2+ imaging (GCaMP) on clock neurons after stimulating the cho neurons directly by heat or after ectopic expression of inducible Trp channels (trpM or trpA1). Finally, as cho are mechanoreceptors, specific mechanical stimulation of the cho may mimic temperature entrainment. We have preliminary evidence that stimulation by 50-200 Hz vibrations in a 12h ‘stimulation’: 12h ‘silence’ regime is able to synchronize locomotor behaviour in a similar way to temperature cycles. We now wish to see whether temperature entrainment mutants also abolish entrainment to vibration. This will ultimately show if the mechanisms underlying mechano- and temperature reception are similar.

Results and milestones

1) Month 8: Project plan & personal development plan for individual training requirements
2) Month 14 Report of experimental results and plans for publication
3) Month 26 Report of detailed research plans, first results, and potential experimental problems
4) Month 36 Publication drafted

Synergies, Risks & Exploitation

Project enhanced by neuroanatomical expertise of Wuerzburg and CNRS. Risks, GRASP and brainbow are very sophisticated techniques. If we encounter some difficulties with brainbow we could use Flybow. How the circadian clock responds to temperature changes is highly relevant for the insect release programmes of our SMEs

See more Work Packages in Research Area B