PhD Thesisstarted in Oct 2009
Evolution of coreceptors in insect olfaction
Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät
First Supervisor: Prof. Dr. B.S. Hansson
Co-Supervisor(s): Dr. E. Grosse-Wilde, Prof. Dr. R. Beutel (FSU) Diploma Thesis2009
Die Gehirnarchitektur bei apterygoten Insekten und basalen Gruppen der Pterygota: Evolution des zentralen olfaktorischen Pfades der Insekten
Friedrich-Schiller-Universität Jena, Biologisch-Pharmazeutische Fakultät
First Supervisor: Prof. Dr. B.S. Hansson
Co-Supervisor(s): PD Dr. D. Wicher Current Research (PhD Thesis):
The detection of volatile cues is central for many insect behaviors, for example host detection or identification of viable mates. Odors are detected by olfactory receptors (ORs) localized in the dendritic membrane of olfactory sensory neurons. Insect ORs function as heteromultimers composed of at least one ligand specific receptor and one coreceptor (ORCo). In comparison to the ligand specific ORs that are extremely variable, ORCo is highly conserved within the insects with homologues identified in Diptera, Lepidoptera, Coleoptera, Hymenoptera, Orthoptera, etc. ORs are hypothesized to have a common ancestry with gustatory receptors (GRs). In contrast to the insect specific ORs, GRs were identified across arthropods. Recently, members of a distinct group of receptors related to ionotropic glutamate receptors (IRs) were established to function as olfactory receptors as well. These IRs are expressed in olfactory organs across Protostomia. Several questions are obvious: When did the OR gene family appears during evolution? What is their ancestry? When did ORCo appear?
My research is focused on an old insect group, the Archaeognatha or jumping bristletails. Archaeognatha are wingless insects that emerged about 390 million years ago. They are most probably the sistergroup of all other insects and therefore a good target to study the evolution of insect ORs and the insect olfactory system in general. Using a wide range of molecular techniques, including transcriptom analysis, microarrays, as well as immunohistochemistry we were not able to detect the presence of any OR, including ORCo, although the much older IRs and GRs are clearly present. Fluorescent in situ hybridization allowed us to ascertain that the identified IRs are indeed expressed in olfactory sensory neurons. Our findings indicate that ORs did not arise as an adaption to a terrestrial lifestyle, but rather evolved later in insect evolution.
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