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Weakly Electric Fish (weakly + electric_fish)
Selected AbstractsMaze Learning and Recall in a Weakly Electric Fish, Mormyrus rume proboscirostris Boulenger (Mormyridae, Teleostei),ETHOLOGY, Issue 10 2010Alice G. Walton Mormyrus rume proboscirostris, African weakly electric fish, were trained to seek shelter in a meander maze, and following path acquisition released into the empty arena with all maze cues removed, either from the original start box or from a novel site (recall). We demonstrate that fish use their active electrosense, sight, and lateral line synergistically in maze acquisition and recall. In the presence of an electric roadmap consisting of an array of aluminum and Plexiglas objects, fish employed landmark orientation. But fish ignored visual markers and relied on internalized motor routines, which was inconsistent with evidence for cognitive mapping. [source] Androgen modulates the kinetics of the delayed rectifying K+ current in the electric organ of a weakly electric fishDEVELOPMENTAL NEUROBIOLOGY, Issue 12 2007M. Lynne McAnelly Abstract Weakly electric fish such as Sternopygus macrurus utilize a unique signal production system, the electric organ (EO), to navigate within their environment and to communicate with conspecifics. The electric organ discharge (EOD) generated by the Sternopygus electric organ is quasi-sinusoidal and sexually dimorphic; sexually mature males produce long duration EOD pulses at low frequencies, whereas mature females produce short duration EOD pulses at high frequencies. EOD frequency is set by a medullary pacemaker nucleus, while EOD pulse duration is determined by the kinetics of Na+ and K+ currents in the electric organ. The inactivation of the Na+ current and the activation of the delayed rectifying K+ current of the electric organ covary with EOD frequency such that the kinetics of both currents are faster in fish with high (female) EOD frequency than those with low (male) EOD frequencies. Dihydrotestosterone (DHT) implants masculinize the EOD centrally by decreasing frequency at the pacemaker nucleus (PMN). DHT also acts at the electric organ, broadening the EO pulse, which is at least partly due to a slowing of the inactivation kinetics of the Na+ current. Here, we show that chronic DHT treatment also slows the activation and deactivation kinetics of the electric organ's delayed rectifying K+ current. Thus, androgens coregulate the time-varying kinetics of two distinct ion currents in the EO to shape a sexually dimorphic communication signal. © 2007 Wiley Periodicals, Inc. Develop Neurobiol, 2007 [source] Maze Learning and Recall in a Weakly Electric Fish, Mormyrus rume proboscirostris Boulenger (Mormyridae, Teleostei),ETHOLOGY, Issue 10 2010Alice G. Walton Mormyrus rume proboscirostris, African weakly electric fish, were trained to seek shelter in a meander maze, and following path acquisition released into the empty arena with all maze cues removed, either from the original start box or from a novel site (recall). We demonstrate that fish use their active electrosense, sight, and lateral line synergistically in maze acquisition and recall. In the presence of an electric roadmap consisting of an array of aluminum and Plexiglas objects, fish employed landmark orientation. But fish ignored visual markers and relied on internalized motor routines, which was inconsistent with evidence for cognitive mapping. [source] Adaptive radiation in African weakly electric fish (Teleostei: Mormyridae: Campylomormyrus): a combined molecular and morphological approachJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 1 2007P. G. D. FEULNER Abstract We combined multiple molecular markers and geometric morphometrics to revise the current taxonomy and to build a phylogenetic hypothesis for the African weakly electric fish genus Campylomormyrus. Genetic data (2039 bp DNA sequence of mitochondrial cytochrome b and nuclear S7 genes) on 106 specimens support the existence of at least six species occurring in sympatry. We were able to further confirm these species by microsatellite analysis at 16 unlinked nuclear loci and landmark-based morphometrics. We assigned them to nominal taxa by comparisons to type specimens of all Campylomormyrus species recognized so far. Additionally, we showed that the shape of the elongated trunk-like snout is the major source of morphological differentiation among them. This finding suggests that the radiation of this speciose genus might have been driven by adaptation to different food sources. [source] | ||||||||||