| Title: | Olfactory sensitivity to steroid glucuronates in Mozambique tilapia suggests two distinct and specific receptors for pheromone detection |
| Author(s): | Keller-Costa T; Canario AV; Hubbard PC; |
| Address: | "Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal Departamento de Biologia, Universidade de Evora, Apartado 94, 7002-554 Evora, Portugal. Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal. Centre of Marine Sciences (CCMAR), Universidade do Algarve, Campus de Gambelas, 8005-139 Faro, Portugal phubbard@ualg.pt" |
| ISSN/ISBN: | 1477-9145 (Electronic) 0022-0949 (Linking) |
| Abstract: | "Cichlids offer an exciting opportunity to understand vertebrate speciation; chemical communication could be one of the drivers of African cichlid radiation. Chemical signals mediate key aspects in the lives of vertebrates and often are species specific. Dominant male Mozambique tilapia [Oreochromis mossambicus (Peters 1852)] release a sex pheromone, 5beta-pregnan-3alpha,17alpha,20beta-triol 3-glucuronate and its 20alpha-epimer, via their urine. The objective of this study was to assess the sensitivity, specificity and versatility of the olfactory system of O. mossambicus to other steroids and their conjugates using the electro-olfactogram. Oreochromis mossambicus was sensitive to several 3-glucuronidated steroids, but did not respond to prostaglandins, unconjugated steroids or 17- or 20-conjugated steroids. Stimulation of the olfactory epithelium with increasing concentrations (1 pmol l(-1) to 10 mumol l(-1)) of 5beta-pregnan-3alpha,17alpha,20beta-triol 3-glucuronate, 5beta-pregnan-3alpha,17alpha,20alpha-triol 3-glucuronate, 3alpha,17alpha-dihydroxy-5beta-pregnan-20-one 3-glucuronate, etiocholanolone 3alpha-glucuronate and 17beta-estradiol 3-glucuronate produced characteristic sigmoidal concentration-response curves. However, tilapia were most sensitive to 17beta-estradiol-3-glucuronate, which also had the lowest apparent EC50 and maximal response amplitude. Cross-adaptation and binary mixture experiments suggested that 5beta,3alpha-reduced pregnan- and androstan-3-glucuronates share (a) common olfactory receptor(s), whereas 17beta-estradiol 3-glucuronate is detected via (a) distinct olfactory receptor(s). In conclusion, the Mozambique tilapia has evolved high olfactory sensitivity and specificity to 3-glucuronidated steroids through two distinct olfactory receptor types; one detecting a male sex pheromone and a second detecting 17beta-estradiol 3-glucuronate, a putative female-derived signal. However, O. mossambicus differs markedly in its olfactory perception from the more recently derived East African cichlid Astatotilapia burtoni, suggesting that chemical communication could, indeed, be involved in speciation" |
| Keywords: | Animals Electrophysiology Female Glucuronates/metabolism Male Olfactory Mucosa/*physiology *Olfactory Perception Sex Attractants Smell/*physiology Steroids/*metabolism Tilapia/*physiology Chemical communication Cichlid Olfaction Pheromone Receptor Steroid; |
| Notes: | "MedlineKeller-Costa, Tina Canario, Adelino V M Hubbard, Peter C eng Research Support, Non-U.S. Gov't England 2014/10/18 J Exp Biol. 2014 Dec 1; 217(Pt 23):4203-12. doi: 10.1242/jeb.111518. Epub 2014 Oct 16" |
