Intercellular signaling as visualized by endogenous calcium-dependent bioluminescence.
Bioluminescence in the hydrozoan coelenterate Obelia results from calcium activation of a photoprotein contained in light-emitting cells (photocytes) scattered in the animal's endoderm. The influx of calcium into nonluminescent endodermal cells through conventional voltage-dependent calcium channels is required for the excitation-luminescence coupling. Our results suggest that the subsequent diffusion of this calcium, via gap junctions, into the neighboring photocytes triggers a localized luminescence response. Following intense stimulation, the local rise in calcium elicits a secondary wave of luminescence that is supported by a voltage-independent calcium permeability mechanism in the photocyte plasma membrane. These two mechanisms for elevating internal calcium in light-emitting cells can account for the spatial and temporal features of intracellular luminescence in Obelia.
Brehm
P
P
Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
Lechleiter
J
J
Smith
S
S
Dunlap
K
K
D000818:Animals; D002118:Calcium / Q000378:metabolism / Q000494:pharmacology*; D015220:Calcium Channels / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D002450:Cell Communication / Q000502:physiology*; D002462:Cell Membrane / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D002463:Cell Membrane Permeability / Q000187:drug effects / Q000502:physiology; D003063:Cnidaria / Q000166:cytology / Q000502:physiology*; D004707:Endoderm / Q000166:cytology; D008163:Luminescent Measurements; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology
D015220:Calcium Channels; D002118:Calcium