Mechanisms of Olfaction in Insects - ResearchSpace@Auckland ...

Functional characterisation of Epiphyas postvittana odorant receptor 1 35
species using degenerate PCR, transcriptome sequencing and whole genome
sequencing techniques; E. postvittana (Jordan et al., 2009), A. polyphemus (Forstner
et al., 2009), B. mori (Sakurai et al., 2004; Krieger et al., 2005; Nakagawa et al.,
2005; Wanner et al., 2007; Tanaka et al., 2009), P. xylostella, M. separata, D. indica
(Mitsuno et al., 2008), H. virescens (Krieger et al., 2002; Krieger et al., 2004),
Spodoptera exigua (Xiu et al., 2004) A. pernyi (Krieger et al., 2003), M. sexta (Patch
et al., 2009; Große-Wilde et al., 2010) and eight different Ostrinia species (Miura et
al., 2009; Wanner et al., 2010). The majority of ORs from moths have been identified
in B. mori and H. virescens.
Typically in studies, the usual approach to characterise novel OR genes are to group
them into clades based on their phylogenetic relationships. The expression levels of
the ORs can be then tested in different tissues in male and female moths, those that
show sex biased expression patterns are classified as putative pheromone receptors.
De-orphaning the receptors using available assay systems is carried out to confirm
they are pheromone receptors and identify which components of sex pheromone
blends they bind. Pheromone receptors have so far been identified and functionally
characterised for a number of moth species including B. mori, H. virescens, P.
xylostella, M. separata, D. indica, A. polyphemus, O. scapulalis, O. latipennis, and O.
nubulalis, see section 1.5.2.1 (Nakagawa et al., 2005; Mitsuno et al., 2008; Forstner et
al., 2009; Miura et al., 2009; Wang et al., 2010).
Attempts to decode the olfactory systems of moths have seen the use of EAG to show
the recognition of a vast range of important plant semiochemicals including esters,
terpenes, alcohols, aliphatics and aldehydes by different species of moths. These may
aid the insects in locating oviposition sites and food sources (Suckling et al., 1996;
Suckling et al., 1996; Fraser et al., 2003; Das et al., 2007). This method gives a broad
picture of the wide range of volatiles recognised by the moth, however, information
on the receptive range of individual ORs, which is at the forefront of investigating
into the molecular mechanisms of insect olfaction is lacking. Several characterisation
assay systems have been successfully developed and used to confer functionality to
individual ORs over the years. These include either the in vivo empty-neuron system
developed in Drosophila (Stortkuhl and Kettler, 2001; Dobritsa et al., 2003) or in
vitro assays in heterologous cell-based expression systems (Wetzel et al., 2001;