Effect of co-expression of Spodoptera olfactory receptors on Drosophila odour perception

Sammanfattning: Like humans, other animals are also able to smell and differentiate a large number of odours with great accuracy. Chemosensory signals play a vital role in locating host plants by insects. Drosophila has a well-developed olfactory system which can differentiate between different odours and recognize food, oviposition sites and potential mates. Studies of olfactory behaviour in invertebrates may aid in understanding the link between odour recognition and behaviour. Some selected olfactory receptors from Spodoptera (Slit-ORs) were co-expressed in Drosophila with its olfactory receptor Or92-a in the Drosophila ab1B neuron type by means of existing DmelOR92a-Gal4 and UAS-SlitOR lines. Drosophila olfactory receptor 92-a responses to acetoin. Acetoin is also detected by Drosophila olfactory receptor Or9-a which is located in ab8B neuron. Olfactory mediated behavioural responses of flies having modified olfactory systems were investigated to different odours, to determine which (if any) of the receptor modifications would change odour preference of flies. An olfactory attraction assay was employed for this purpose. In parallel, DNA sequences were cloned to prepare a transformation vector construct for stable expression of the Slit-ORs in DmelOR92-a neurons, containing the promoter sequence for Drosophila olfactory receptor Or92-a and selected olfactory receptor sequences from Spodoptera. The sequences were aimed to be cloned into a suitable Drosophila germ line transformation vector attB. There was no significant effect of co-expressing SlitOR in OR92-a neuron on the olfactory behaviour of D. melanogaster OR-a, OR-b, OR-c and OR6 receptors. Most strains were significantly attracted to acetoin, similar to wild type flies. In contrast, very few were attracted to the corresponding ligands for the Slit-ORs, regardless whether the Spodoptera OR was expressed or not.