title: A superfast muscle in the complex sonic apparatus of Ophidion rochei (Ophidiiformes): histological and physiological approaches.
abstract: In teleosts, superfast muscles are generally associated with the swimbladder wall, whose vibrations result in sound production. In Ophidion rochei, three pairs of muscles were named 'sonic' because their contractions affect swimbladder position: the dorsal sonic muscle (DSM), the intermediate sonic muscle (ISM), and the ventral sonic muscle (VSM). These muscles were investigated thanks to electron microscopy and electromyography in order to determine their function in sound production. Fibers of the VSM and DSM were much thinner than the fibers of the ISM and epaxial musculature. However, only VSM fibers had the typical ultrastructure of superfast muscles: low proportion of myofibrils, and high proportions of sarcoplasmic reticulum and mitochondria. In females, each sound onset was preceded by the onset of electrical activity in the VSM and the DSM (ISM was not tested). The electromyograms of the VSM were very similar to the waveforms of the sounds: means for the pulse period were 3.6±0.5 and 3.6±0.7 ms, respectively. This shows that the fast VSM (ca. 280 Hz) is responsible for the pulse period and fundamental frequency of female sounds. DSM electromyograms were generally characterized by one or two main peaks followed by periods of lower electrical activity, which suggests a sustained contraction over the course of the sound. The fiber morphology of the ISM and its antagonistic position relative to the DSM are not indicative of a muscle capable of superfast contractions. Overall, this study experimentally shows the complexity of the sound production mechanism in the nocturnal fish O. rochei.
authors: Laboratoire de Morphologie Fonctionnelle et Evolutive, AFFISH-RC, Institut de chimie, Bât. B6c, Université de Liège, B-4000 Liège, Belgium loic.kever@ulg.ac.be.
authors: Loïc
authors: L
authors: Kéver
authors: Département d'Ecologie et de Gestion de la Biodiversité, Muséum National d'Histoire Naturelle, 57 rue Cuvier, Case postale 55, 75231, Paris Cedex 5, France.
authors: Kelly S
authors: KS
authors: Boyle
authors: Institute of Oceanography and Fisheries, POB 500, 21000 Split, Croatia.
authors: Branko
authors: B
authors: Dragičević
authors: Institute of Oceanography and Fisheries, POB 500, 21000 Split, Croatia.
authors: Jakov
authors: J
authors: Dulčić
authors: Laboratoire de Morphologie Fonctionnelle et Evolutive, AFFISH-RC, Institut de chimie, Bât. B6c, Université de Liège, B-4000 Liège, Belgium.
authors: Eric
authors: E
authors: Parmentier
mesh_terms: D000400:Air Sacs / Q000502:physiology* / Q000648:ultrastructure; D000818:Animals; D004576:Electromyography; D005260:Female; D005399:Fishes / Q000033:anatomy & histology* / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018485:Muscle Fibers, Skeletal / Q000502:physiology; D018482:Muscle, Skeletal / Q000502:physiology* / Q000648:ultrastructure; D009210:Myofibrils; D014828:Vocalization, Animal
keywords: Fast muscle; Fish; Sound