Sensory cues for the gradual frequency fall responses of the gymnotiform electric fish, Rhamphichthys rostratus

Kawasaki, Masashi; Prather, James; Guo, Yuan-Xing

doi:10.1007/bf00190176

Cited by 8 publications

(1 citation statement)

References 17 publications

(29 reference statements)

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“…All Rhamphichthys species generate electrical pulses that are used to communicate and identify mating partners and other species. This trait allows them to be nocturnal and live in rivers with dark waters (Kawasaki et al 1996, Crampton 1998, Nanjappa et al 2000, Gouvêa et al 2002). …”

Section: Introductionmentioning

confidence: 99%

Karyotypic similarities between two species of Rhamphichthys (Rhamphichthyidae, Gymnotiformes) from the Amazon basin

Silva¹,

Nagamachi²,

Silva³

et al. 2013

CCG

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The family Rhamphichthyidae includes three genera: Rhamphichthys Müller et Troschel, 1846, Gymnorhamphichthys M. M. Ellis, 1912 and Iracema Triques, 1996. From this family, only the species Rhamphichthys hanni Meinken, 1937 has had its karyotype described. Here, we describe the karyotypes of two additional Rhamphichthys species: Rhamphichthys marmoratus Castelnau, 1855 from the Reserva de Desenvolvimento Sustentável Mamirauá, Amazonas state and Rhamphichthys prope rostratus Linnaeus, 1766 from Pará state, both in Brazil. Our karyotypic analyses demonstrated that the diploid number is conserved for the genus (2n = 50), but the karyotypic formulas (KFs) differed between Rhamphichthys marmoratus (44m/sm+6a) and Rhamphichthys prope rostratus (42m/sm+8a). In both species, the constitutive heterochromatin (CH) was located in the centromeric region of most chromosomes. Large heterochromatic blocks were found on the long arms of pairs 4 and 14 in Rhamphichthys marmoratus and on chromosomes 3, 4 and 19 in Rhamphichthys prope rostratus, which also has a heteromorphism in chromosome pair 1. The CH was DAPI positive, indicating that it is rich in AT base pairs. The Nucleolus Organizer Region (NOR) showed staining at a single location in both species: the long arm of pair 1 in Rhamphichthys marmoratus and the long arm of pair 12 in Rhamphichthys prope rostratus, where it showed a size heteromorphism. CMA3 staining coincided with that of Ag-NOR, indicating that the ribosomal genes contain interspaced GC-rich sequences. FISH with an 18S rDNA probe confirmed that there is only one NOR site in each species. These results can be used as potential cytogenetic markers for fish populations, and comparative analysis of the karyotypes of Hypopygus Hoedman, 1962, Rhamphichthys and Steatogenys Boulenger, 1898 suggests that the first two genera diverged later that the third.

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Section: Introductionmentioning

confidence: 99%

Karyotypic similarities between two species of Rhamphichthys (Rhamphichthyidae, Gymnotiformes) from the Amazon basin

Silva¹,

Nagamachi²,

Silva³

et al. 2013

CCG

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Motor control of the jamming avoidance response of Apteronotus leptorhynchus: evolutionary changes of a behavior and its neuronal substrates

et al. 1996

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The two closely related gymnotiform fishes, Apteronotus and Eigenmannia, share many similar communication and electrolocation behaviors that require modulation of the frequency of their electric organ discharges. The premotor linkages between their electrosensory system and their medullary pacemaker nucleus, which controls the repetition rate of their electric organ discharges, appear to function differently, however. In the context of the jamming avoidance response, Eigenmannia can raise or lower its electric organ discharge frequency from its resting level. A normally quiescent input from the diencephalic pre-pacemaker nucleus can be recruited to raise the electric organ discharge frequency above the resting level. Another normally active input, from the sublemniscal pre-pacemaker nucleus, can be inhibited to lower the electric organ discharge frequency below the resting level (Metzner 1993). In contrast, during a jamming avoidance response, Apteronotus cannot lower its electric organ discharge frequency below the resting level. The sublemniscal pre-pacemaker is normally completely inhibited and release of this inhibition allows the electric organ discharge frequency to rise during the jamming avoidance response. Further inhibition of this nucleus cannot lower the electric organ discharge frequency below the resting level. Lesions of the diencephalic pre-pacemaker do not affect performance of the jamming avoidance response. Thus, in Apteronotus, the sublemniscal pre-pacemaker alone controls the changes of the electric organ discharge frequency during the jamming avoidance response.

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Encoding and processing biologically relevant temporal information in electrosensory systems

2006

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Wave-type weakly electric fish are specialists in time-domain processing: behaviors in these animals are often tightly correlated with the temporal structure of electrosensory signals. Behavioral responses in these fish can be dependent on differences in the temporal structure of electrosensory signals alone. This feature has facilitated the study of temporal codes and processing in central nervous system circuits of these animals. The temporal encoding and mechanisms used to transform temporal codes in the brain have been identified and characterized in several species, including South American gymnotid species and in the African mormyrid genus Gymnarchus. These distantly related groups use similar strategies for neural computations of information on the order of microseconds, milliseconds, and seconds. Here, we describe a suite of mechanisms for behaviorally relevant computations of temporal information that have been elucidated in these systems. These results show the critical role that behavioral experiments continue to have in the study of the neural control of behavior and its evolution.

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Sensory cues for the gradual frequency fall responses of the gymnotiform electric fish, Rhamphichthys rostratus

Cited by 8 publications

References 17 publications

Karyotypic similarities between two species of Rhamphichthys (Rhamphichthyidae, Gymnotiformes) from the Amazon basin

Karyotypic similarities between two species of Rhamphichthys (Rhamphichthyidae, Gymnotiformes) from the Amazon basin

Motor control of the jamming avoidance response of Apteronotus leptorhynchus: evolutionary changes of a behavior and its neuronal substrates

Encoding and processing biologically relevant temporal information in electrosensory systems

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