Mechanisms of signal transduction in photo-stimulated secretion in Phaeocystis globosa.
Phaeocystis globosa, a leading agent in marine carbon cycling, releases its photosynthesized biopolymers via regulated exocytosis. Release is elicited by blue light and relayed by a characteristic cytosolic Ca(2+) signal. However, the source of Ca(2+) in these cells has not been established. The present studies indicate that Phaeocystis' secretory granules work as an intracellular Ca(2+) oscillator. Optical tomography reveals that photo-stimulation induces InsP(3)-triggered periodic lumenal [Ca(2+)] oscillations in the granule and corresponding out-of-phase cytosolic oscillations of [Ca(2+)] that trigger exocytosis. This Ca(2+) dynamics results from an interplay between the intragranular polyanionic matrix, and two Ca(2+)-sensitive ion channels located on the granule membrane: an InsP(3)-receptor-Ca(2+) channel, and an apamin-sensitive K(+) channel.
Quesada
Ivan
I
Department of Bioengineering, University of Washington, Friday Harbor Laboratories, 620 University Road, Friday Harbor, Seattle, WA 98195, USA.
Chin
Wei-Chun
WC
Verdugo
Pedro
P
D020013:Calcium Signaling / Q000502:physiology* / Q000528:radiation effects; D005089:Exocytosis / Q000502:physiology* / Q000528:radiation effects; D007473:Ion Channels / Q000378:metabolism; D017136:Ion Transport / Q000502:physiology / Q000528:radiation effects; D008027:Light; D000459:Phaeophyceae / Q000166:cytology / Q000502:physiology*; D022142:Secretory Vesicles / Q000378:metabolism*; D014054:Tomography
D007473:Ion Channels