Candidate chemoreceptor subfamilies differentially expressed in the chemosensory organs of the mollusc Aplysia

<p>Abstract</p> <p>Background</p> <p>Marine molluscs, as is the case with most aquatic animals, rely heavily on olfactory cues for survival. In the mollusc <it>Aplysia californica</it>, 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.</p> <p>Results</p> <p>Here we show that novel multi-transmembrane proteins with similarity to rhodopsin G-protein coupled receptors are expressed in sensory epithelia microdissected from the <it>Aplysia </it>rhinophore. Analysis of the <it>A. californica </it>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 <it>Aplysia </it>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 Gα_q, Gα_i, and Gα_oare also expressed in the rhinophore sensory epithelium.</p> <p>Conclusion</p> <p>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 <it>Aplysia </it>involves species- or lineage-specific families of chemosensory receptors.</p

Pancreatic somatostatinoma with obscure inhibitory syndrome and mixed pathological pattern*

Somatostatinoma is a very rare neuroendocrine tumor that originates from D cells and accounts for less than 1% of all gastrointestinal endocrine tumors. The duodenum is the most frequent site for this tumor, followed by the pancreas. We here describe a 46-year-old Chinese woman who developed pancreatic somatostatinoma presenting with the characteristic “inhibitory” syndrome, but the symptoms were obscure and seemingly uncorrelated. This case is also unique for its large tumor size and mixed pathological pattern. Distal pancreatectomy was performed, and the patient has remained well since operation. As the syndromes of somatostatinoma may be obscure and atypical, clinicians should review all clinical findings to obtain an accurate diagnosis. Aggressive surgery is preferred to improve the survival