Cellular mechanisms of odour detection in the olfactory system of the
red flour beetle Tribolium castaneum

The detection of volatile substances is a very important sense for insects. Recognition of odours and pheromones leads insects to food sources and mating partners and can elicit different behaviours like fear, aggression and sexuality. Olfaction in insects is mediated by olfactory sensory neurons (OSNs) which are located in hairlike structures, the so called “olfactory sensilla”, on the antennae and mouthparts. Recent studies showed, that in the “sensilla trichodea”, the dendrites of the OSNs express not only a classical odorant receptor (OR) and the odorant receptor coreceptor (Orco) but also an additional molecular element that is essential for the recognition of odorants known as the “sensory neuron membrane protein” (SNMP). The importance of SNMPs was demonstrated in recent studies in the vinegar fly Drosophila melanogaster. These studies showed that mutant flies that lack SNMP1 could not detect the aggregation pheromone cis-vaccenyl acetate (cVA) anymore.

During annotation of the genome of Tribolium castaneum seven genes were found that could encode for Sensory Neuron Membrane Proteins. In other insects just two SNMPs are described.
This rises many questions that I want to answer in my research project:

• Does Tribolium castaneum use more SNMPs than other insects?

• Which cell types express the different SNMPs?

• What is the function of the different SNMPs?