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BMC Biol

Title:		Candidate chemoreceptor subfamilies differentially expressed in the chemosensory organs of the mollusc Aplysia
Author(s):		Cummins SF; Erpenbeck D; Zou Z; Claudianos C; Moroz LL; Nagle GT; Degnan BM;
Address:		"School of Biological Sciences, The University of Queensland, Brisbane, Queensland 4072, Australia. s.cummins@uq.edu.au"
Journal Title:		BMC Biol
Year:		2009
Volume:		20090604
Issue:
Page Number:		28 -
DOI:		10.1186/1741-7007-7-28
ISSN/ISBN:		1741-7007 (Electronic) 1741-7007 (Linking)
Abstract:		"BACKGROUND: Marine molluscs, as is the case with most aquatic animals, rely heavily on olfactory cues for survival. In the mollusc Aplysia californica, mate-attraction is mediated by a blend of water-borne protein pheromones that are detected by sensory structures called rhinophores. The expression of G protein and phospholipase C signaling molecules in this organ is consistent with chemosensory detection being via a G-protein-coupled signaling mechanism. RESULTS: Here we show that novel multi-transmembrane proteins with similarity to rhodopsin G-protein coupled receptors are expressed in sensory epithelia microdissected from the Aplysia rhinophore. Analysis of the A. californica genome reveals that these are part of larger multigene families that possess features found in metazoan chemosensory receptor families (that is, these families chiefly consist of single exon genes that are clustered in the genome). Phylogenetic analyses show that the novel Aplysia G-protein coupled receptor-like proteins represent three distinct monophyletic subfamilies. Representatives of each subfamily are restricted to or differentially expressed in the rhinophore and oral tentacles, suggesting that they encode functional chemoreceptors and that these olfactory organs sense different chemicals. Those expressed in rhinophores may sense water-borne pheromones. Secondary signaling component proteins Galphaq, Galphai, and Galphao are also expressed in the rhinophore sensory epithelium. CONCLUSION: The novel rhodopsin G-protein coupled receptor-like gene subfamilies identified here do not have closely related identifiable orthologs in other metazoans, suggesting that they arose by a lineage-specific expansion as has been observed in chemosensory receptor families in other bilaterians. These candidate chemosensory receptors are expressed and often restricted to rhinophores and oral tentacles, lending support to the notion that water-borne chemical detection in Aplysia involves species- or lineage-specific families of chemosensory receptors"
Keywords:		"Amino Acid Sequence Animals Aplysia/*genetics/ultrastructure *Gene Expression Profiling Gene Expression Regulation Genome/genetics Immunohistochemistry Microscopy, Electron, Scanning Molecular Sequence Data Organ Specificity/genetics Phylogeny Receptors, ;"
Notes:		"MedlineCummins, Scott F Erpenbeck, Dirk Zou, Zhihua Claudianos, Charles Moroz, Leonid L Nagle, Gregg T Degnan, Bernard M eng Research Support, N.I.H., Extramural Research Support, Non-U.S. Gov't Research Support, U.S. Gov't, Non-P.H.S. England 2009/06/06 BMC Biol. 2009 Jun 4; 7:28. doi: 10.1186/1741-7007-7-28"