Putative Steroidal Sex Pheromones in the Round Goby, Neogobius Melanostomus
In many species of teleost fish, released steroids, prostaglandins, and their metabolites appear to induce behavioural and physiological responses. Our electro-olfactogram (EOG) studies have shown that the olfactory system of the round goby (Neogobius melanostomus) does not detect prostaglandins but detects free and conjugated 18-, 19- and 21-carbon steroids which may have pheromonal functions. Our EOG cross-adaptation studies have indicated that the detected steroids act via four distinct olfactory receptor classes (named after the most potent compound in each): estrone, estradiol-glucuronide, etiocholanolone, and dehydroepiandrosterone-sulphate. Steroids from three of the four receptor classes induced a consistent and transient (15-18 min) increase in the ventilation rate of males. Here, we report the use of the male ventilatory response in one set of behavioural cross-adaptation experiments designed to determine if the sensory discrimination of detected steroids evident in EOG cross-adaptation experiments is matched by behavioural discrimination. These experiments showed that after adaptation to the first steroid, the second steroid induces an increase in ventilation rate only if it acts on a different receptor class. Together, the EOG and behavioural cross-adaptation studies in N. melanostomus demonstrate a good correlation between odour discrimination at the sensory and behavioural level and that males are capable of perceiving single steroids.
KeywordsOlfactory Receptor Olfactory Epithelium Ventilation Rate Round Goby Odour Discrimination
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