Repetitive Ca2+ spikes in a unicellular green alga.
Cytosolic Ca2+ activity ([Ca2+]cy) and membrane potential were measured simultaneously in the unicellular green alga Eremosphaera viridis. Steady state [Ca2+]cy was about 160 nM. A 'light-off' stimulus induced a transient elevation of [Ca2+]cy ([Ca2+]cy spike) in parallel with a transient hyperpolarization of the plasma membrane. Caffeine and Sr2+, known to release Ca2+ from intracellular stores in animal cells, induced repetitive [Ca2+]cy spikes in Eremosphaera which were always accompanied by parallel repetitive transient hyperpolarizations. These transient hyperpolarizations could be used as an indicator for [Ca2+]cy spikes. Repetitive [Ca2+]cy spikes in Eremosphaera were similar to repetitive [Ca2+]cy spikes in excitable animal cells. The mechanisms underlying these [Ca2+]cy oscillations seem to be comparable in animal and plant cells.
Bauer
C S
CS
Lehrstuhl Botanik I, Universität Würzburg, Germany.
Plieth
C
C
Hansen
U P
UP
Sattelmacher
B
B
Simonis
W
W
Schönknecht
G
G
D002110:Caffeine / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D000460:Chlorophyta; D003600:Cytosol / Q000502:physiology; D008564:Membrane Potentials / Q000187:drug effects; D010507:Periodicity
D002110:Caffeine; D002118:Calcium