Mechanisms of Olfaction in Insects - ResearchSpace@Auckland ...
Mechanisms of Olfaction in Insects - ResearchSpace@Auckland ...
Mechanisms of Olfaction in Insects - ResearchSpace@Auckland ...
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General Introduction 15<br />
Tanaka et al., 2009), and tissue expression analysis has identified four ORs<br />
(BmOR19, BmOR30, BmOR45 and BmOR47) with higher expression levels <strong>in</strong><br />
female than male antennae (Anderson et al., 2009). In situ hybridisation has shown<br />
BmOR19 to be co-localised with either BmOR45 or BmOR47. Heterologous<br />
expression <strong>of</strong> three <strong>of</strong> these ORs <strong>in</strong> Sf9 <strong>in</strong>sect cells has identified BmOR19 to be<br />
tuned to l<strong>in</strong>alool, and BmOR45 and BmOR47 to be tuned to benzoic acid, 2-<br />
phenylethanol and benzaldehyde (Anderson et al., 2009).<br />
Mitsuno et al. (2008) identified ten ORs from three different moth species; Plutella<br />
xylostella (PxOR1, PxOR2, PxOR3 and PxOR4), Mythimna separate (MsOR1,<br />
MsOR2 and MsOR3), and Diaphania <strong>in</strong>dica (DiOR1, DiOR2 and DiOR3), through<br />
degenerate PCR <strong>of</strong> male antennal cDNA <strong>of</strong> the moths with primers designed from the<br />
conserved regions <strong>of</strong> BmOR1 and other male-specific ORs. Three <strong>of</strong> the ORs were<br />
homologues <strong>of</strong> the highly conserved BmOR2. Five <strong>of</strong> the ORs (PxOR1, PxOR4,<br />
DiOR1, MsOR1 and MsOR3) were expressed exclusively <strong>in</strong> male antennae, while<br />
two (PxOR3, DiOR3) were expressed <strong>in</strong> both male and female antennae, although<br />
higher levels were observed <strong>in</strong> male antennae. PxOR1, MsOR1 and DiOR1 were<br />
exclusively expressed <strong>in</strong> male antennae and shown to b<strong>in</strong>d sex pheromone<br />
component(s) <strong>of</strong> the respective moths (P. xylostella b<strong>in</strong>ds (Z)-11-hexadecenal; M.<br />
separate b<strong>in</strong>ds (Z)-11-hexadecenyl acetate and D. <strong>in</strong>dica b<strong>in</strong>ds (E)-11-Hexadecenal)<br />
(Mitsuno et al., 2008).<br />
M. sexta ORs were identified by differential screen<strong>in</strong>g <strong>of</strong> a male antennal cDNA<br />
library (OR1), degenerate PCR (OR2, which is the homologue <strong>of</strong> BmOR2) and from a<br />
subtracted male antennal transcriptome (OR3) (Patch et al., 2009). Tissue expression<br />
analysis revealed MsexOR1 to be expressed <strong>in</strong> male antennae and MsexOR3 to be<br />
expressed highly <strong>in</strong> female antennae. Three further ORs, named MsexOR4, MsexOR5<br />
and MsexOR6 have been identified <strong>in</strong> M. sexta recently from a subtractive male<br />
antennal cDNA library (Große-Wilde et al., 2010). MsexOR4 has been shown to be<br />
expressed <strong>in</strong> male antennae while MsexOR5 and MsexOR6 have been detected <strong>in</strong><br />
female antennae. Functional analysis <strong>of</strong> MsexOR1 with pheromone components did<br />
not reveal any ligands for this receptor as yet and MsexOR4 has been postulated to<br />
b<strong>in</strong>d one <strong>of</strong> the sex pheromone components <strong>of</strong> M. sexta however, no functional data<br />
for odorant b<strong>in</strong>d<strong>in</strong>g <strong>of</strong> these ORs are available as yet.