title: Chromatophore activity during natural pattern expression by the squid Sepioteuthis lessoniana: contributions of miniature oscillation.
abstract: Squid can rapidly change the chromatic patterns on their body. The patterns are created by the expansion and retraction of chromatophores. The chromatophore consists of a central pigment-containing cell surrounded by radial muscles that are controlled by motor neurons located in the central nervous system (CNS). In this study we used semi-intact squid (Sepioteuthis lessoniana) displaying centrally controlled natural patterns to analyze spatial and temporal activities of chromatophores located on the dorsal mantle skin. We found that chromatophores oscillated with miniature expansions/retractions at various frequencies, even when the chromatic patterns appear macroscopically stable. The frequencies of this miniature oscillation differed between "feature" and "background" areas of chromatic patterns. Higher frequencies occurred in feature areas, whereas lower frequencies were detected in background areas. We also observed synchronization of the oscillation during chromatic pattern expression. The expansion size of chromatophores oscillating at high frequency correlated with the number of synchronized chromatophores but not the oscillation frequency. Miniature oscillations were not observed in denervated chromatophores. These results suggest that miniature oscillations of chromatophores are driven by motor neuronal activities in the CNS and that frequency and synchrony of this oscillation determine the chromatic pattern and the expansion size, respectively.
authors.affiliation: Graduate School of Science and Technology, Keio University, Yokohama, Kanagawa, Japan.
authors.forename: Mamiko
authors.initials: M
authors.lastname: Suzuki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Kimura
authors.forename: Hiroto
authors.initials: H
authors.lastname: Ogawa
authors.forename: Kohji
authors.initials: K
authors.lastname: Hotta
authors.forename: Kotaro
authors.initials: K
authors.lastname: Oka
mesh_terms: D000818:Animals; D001921:Brain / Q000502:physiology; D002452:Cell Count; D048429:Cell Size; D002856:Chromatophores / Q000166:cytology*; D049832:Decapodiformes / Q000033:anatomy & histology* / Q000166:cytology* / Q000502:physiology; D010858:Pigmentation