The Drosophila olfactome

Olfactory sensory systems of varying complexity have evolved to deal with the complex chemical environment that animals are living in. Albeit their differences, most of these systems have in common that they are able to detect a very high number of different chemical stimuli with relatively few classes of olfactory sensory neurons. To understand how olfactory sensory systems are able to effectively sample the highly complex multidimensional chemical space, it is desirable to gather as much information as possible about how stimuli are coded by the system. Ideally we would know the complete olfactome: The responses of all individual sensory neurons to all the possible odorants in all possible mixtures and at all possible concentrations.

Using the fruitfly Drosophila as a model organism, with its comparably simple olfactory sensory system and the availability of genetic tools that allow to specifically target individual sensory neurons, makes it feasible to come close to the olfactome. To achieve this we use high-throughput imaging techniques and we created the DoOR project that integrates all available Drosophila odor-response data that is published into a single consensus database.

Encoding of odor mixtures

The olfactory stimuli that an olfactory sensory system has to deal with usually don’t consist of monomolecular substances in well defined concentrations. Natural odors are multi-component mixtures of varying complexity and concentration. A variety of processes referred to as “mixture interactions” facilitate the coding of these complex stimuli, for example by preventing oversaturation of the system. Mixture interactions happen at different levels of olfactory systems. So far I focused my research on interactions that happen in the periphery, on the antenna of Drosophila.

Using insect antenna as chemical sensor

The detection of chemicals is a technically demanding task. While electronic sensors struggle with chemical complexity and rather high detection thresholds, nature evolved olfactory sensory neurons that are able to detect even single odorant molecules. Using natural noses to detect or differentiate odors of interest could thus be a way to derive more potent chemical sensors for a variety of applications. We could recently show, that sensory neuron activation patterns can be extracted from Drosophila antenna and used to differentiate healthy from cancerous breast tissue.