Ciliary reorientation is evoked by a rise in calcium level over the entire cilium.
Internal Ca2+ levels control the pattern of ciliary and flagellar beating in eukaryotes. In ciliates, ciliary reversal is induced by a rise in intra-ciliary Ca2+, but the mechanism by which Ca2+ induces reversal is not known. We injected the fluorescent Ca2+ indicator Calcium Green into a ciliate Didinium nasutum and observed the intra-ciliary Ca2+ level during the initial reversed stroke preceding spontaneous cyclic reversed beating. In D. nasutum, Ca2+ rose throughout the length of the cilia undergoing initial reversed stroke. Electron microscopy with a combined oxalate-pyroantimonate method showed Ca2+ deposits distributed throughout the reversed cilia. We injected caged Ca2+ into D. nasutum and irradiated the base or mid region of the cilia with UV to locally increase Ca2+ concentration. Uncaging Ca2+ in the middle of the cilia produced reversal distally, but not proximally to the site of Ca2+ release. These results strongly suggest that not only Ca2+ influx sites, but also Ca2+ binding sites and vectoral bending machineries for ciliary reversal, are distributed throughout the cilium.
Iwadate
Yoshiaki
Y
Department of Life Science, Faculty of Integrated Arts and Sciences, The University of Tokushima, Tokushima, Japan. iwadate.yoshiaki@nifty.ne.jp
Suzaki
Toshinobu
T
D000818:Animals; D000965:Antimony / Q000737:chemistry; D002118:Calcium / Q000032:analysis / Q000737:chemistry / Q000378:metabolism*; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002923:Cilia / Q000187:drug effects / Q000502:physiology* / Q000648:ultrastructure; D016798:Ciliophora / Q000378:metabolism / Q000502:physiology* / Q000648:ultrastructure; D003911:Dextrans / Q000737:chemistry; D004533:Egtazic Acid / Q000031:analogs & derivatives* / Q000494:pharmacology; D016650:Fluorescein-5-isothiocyanate / Q000031:analogs & derivatives* / Q000737:chemistry; D005456:Fluorescent Dyes / Q000737:chemistry; D007091:Image Processing, Computer-Assisted; D008846:Micromanipulation / Q000379:methods; D046529:Microscopy, Electron, Transmission; D008856:Microscopy, Fluorescence; D009930:Organic Chemicals; D010070:Oxalates / Q000737:chemistry
D003911:Dextrans; D005456:Fluorescent Dyes; D009930:Organic Chemicals; D010070:Oxalates; C015219:fluorescein isothiocyanate dextran; C071336:calcium green; C009002:potassium antimonate; C085112:2-nitrophenyl-EGTA; D004533:Egtazic Acid; D000965:Antimony; D016650:Fluorescein-5-isothiocyanate; D002118:Calcium