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IDENTIFICATION OF THE WESTERN TARNISHED PLANT BUG ( Lygus hesperus ) OLFACTORY CO‐RECEPTOR ORCO: EXPRESSION PROFILE AND CONFIRMATION OF ATYPICAL MEMBRANE TOPOLOGY
Author(s) -
Hull J. Joe,
Hoffmann Eric J.,
Perera Omaththage P.,
Snodgrass Gordon L.
Publication year - 2012
Publication title -
archives of insect biochemistry and physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.576
H-Index - 66
eISSN - 1520-6327
pISSN - 0739-4462
DOI - 10.1002/arch.21042
Subject(s) - biology , olfaction , lygus , olfactory receptor , microbiology and biotechnology , membrane topology , genetics , hemiptera , botany , receptor , ecology , transmembrane domain , miridae
Lygus hesperus (western tarnished plant bug) is an agronomically important pest species of numerous cropping systems. Similar to other insects, a critical component underlying behaviors is the perception and discrimination of olfactory cues. Consequently, the molecular basis of olfaction in this species is of interest. To begin to address this issue, we utilized homology‐based PCR as a commonly accepted abbreviation but if necessary it is polymerase chain reaction methods to identify the L . hesperus olfactory receptor co‐receptor ( O rco) ortholog, a receptor that has been shown to be essential for olfaction. The L. hesperus O rco (Lh O rco) shares significant sequence homology with known O rco proteins in other insects. Parallel experiments using the sympatric sister species, Lygus lineolaris (tarnished plant bug), revealed that the Lygus O rco gene was completely conserved. Surprisingly, a majority of the membrane topology prediction algorithms used in the study predicted Lh O rco to have both the N and C terminus intracellular. In vitro immunofluorescent microscopy experiments designed to probe the membrane topology of transiently expressed Lh O rco, however, refuted those predictions and confirmed that the protein adopts the inverted topology (intracellular N terminus and an extracellular C terminus) characteristic of O rco proteins. RT ‐ PCR analyses indicated that Lh O rco transcripts are predominantly expressed in adult antennae and to a lesser degree in traditionally nonolfactory chemosensory tissues of the proboscis and legs. Expression is not developmentally regulated because transcripts were detected in all nymphal stages as well as eggs. Taken together, the results suggest that L h O rco likely plays a critical role in mediating L . hesperus odorant perception and discrimination.