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Latha Mukunda

   Department of Evolutionary Neuroethology
   Reception & Transduction
 Phone:+49 (0)3641 57 1466Max Planck Institute for Chemical Ecology
 Fax:+49 (0)3641 57 1402Hans-Knöll-Straße 8
  emailD-07745 Jena

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PhD Thesis

2014
Function and regulation of insect olfactory receptors
Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät
First Supervisor: Prof. Dr. B.S. Hansson
Co-Supervisor(s): PD Dr. D. Wicher, S. Heinemann (FSU)

Abstract
In insects odorant detection involves ligand -binding members of Olfactory receptor (OR) gene family along with the co-receptor Or83b. Or83b is highly conserved across insect species and is a broadly expressed co-receptor essential for olfaction in Drosophila melanogaster. The literature contains divergent views of olfactory signal transduction mechanism in insects. Recent studies on heterologous system using OR-OR83b heterodimer complexes showed that the mutations in the putative pore region of Or83b region altered ion permeability. We hypothesize that mutational analysis in putative cation selectivity motif of Or83b co receptor will change the odour evoked response event in the insect. To test our hypothesis we combine our study with genetics, electrophysiology and behavioral techniques to characterize the flies carrying mutations in the putative selectivity pore motif of Or83b.We also aim to understand the stoichiometry formed by the Or83b protein and its physiological significance. Understanding the basic mechanism of odour perception will enable the finding of inhibitors of the channels to create new class of insect repellents.

I am currently investigating the functional properties of the Drosophila odorant co-receptor Orco, especially how protein oligomerization affects the ion channel properties.

Odorant receptors (ORs) in insects form heterodimeric complexes of a ligand binding conventional receptor protein and a highly conserved odorant co-receptor protein (Orco). Odor stimulation of heterologously expressed insect ORs activated a fast ionotropic current followed by a slowly developing metabotropic current. A slowly activating current could be also obtained with cAMP stimulation in cells solely expressing Orco. An analysis of single events revealed a variable step size which may indicate that multiple Orco proteins synchronize their activity. We hypothesize that cAMP promotes synchronization by oligomerization. To test the functional role of Orco oligomerization we produced an Orco dimer and characterized its functional properties by performing calcium imaging and patch clamp experiments.
last updated on 2012-12-04