Journal Article

Strontium-induced repetitive calcium spikes in a unicellular green alga

Bauer, C.S, Popescu, O, Simonis, W, Hansen, U.P, Plieth, C, Bethmann, B, Schonknecht, G

1998

Overview

The divalent cation Sr2+ induced repetitive transient spikes of the cytosolic Ca2+ activity [Ca2+]cy and parallel repetitive transient hyperpolarizations of the plasma membrane in the unicellular green alga Eremosphaera viridis. [Ca2+]cy measurements, membrane potential measurements, and cation analysis of the cells were used to elucidate the mechanism of Sr2+ -induced [Ca2+]cy oscillations. Sr2+ was effectively and rapidly compartmentalized within the cell, probably into the vacuole. The [Ca2+]cy oscillations cause membrane potential oscillations, and not the reverse. The endoplasmic reticulum (ER) Ca2+ -ATPase blockers 2,5-di-tert-butylhydroquinone and cyclopiazonic acid inhibited Sr2+ -induced repetitive [Ca2+]cy spikes, whereas the compartmentalization of Sr2+ was not influenced. A repetitive Ca2+ release and Ca2+ re-uptake by the ER probably generated repetitive [Ca2+]cy spikes in E. viridis in the presence of Sr2+. The inhibitory effect of ruthenium red and ryanodine indicated that the Sr2+ -induced Ca2+ release from the ER was mediated by a ryanodine/cyclic ADP-ribose type of Ca2+ channel. The blockage of Sr2+ -induced repetitive [Ca2+]cy spikes by La3+ or Gd3+ indicated the necessity of a certain influx of divalent cations for sustained [Ca2+]cy oscillations. Based on these data we present a mathematical model that describes the baseline spiking [Ca2+]cy oscillations in E. viridis

• Publisher: American Society of Plant Physiologists
• Subject: Algae / Animal cells / BIOCHEMICAL PATHWAYS / Biological and medical sciences / CALCIO / CALCIUM / CATION / cation exchange / CATIONES / CATIONS / Cell Biology and Signal Transduction / CELL MEMBRANES / Cell physiology / Cell walls / CHLOROPHYCEAE / CHLOROPHYTA / CITOPLASMA / cyclic ADP-ribose / CYTOPLASM / CYTOPLASME / CYTOSOL / ECHANGE D'ION / EQUATIONS / EREMOSPHAERA VIRIDIS / ESTRONCIO / Fundamental and applied biological sciences. Psychology / INDUCTION / INTERCAMBIO IONICO / ION EXCHANGE / MATEMATICAS / MATHEMATICAL MODELS / MATHEMATICS / MATHEMATIQUE / MEASUREMENT / MEDICION / MEMBRANAS CELULARES / MEMBRANE CELLULAIRE / MEMBRANE POTENTIAL / MESURE / MODELE MATHEMATIQUE / MODELOS MATEMATICOS / Molecular and cellular biology / Plant cells / Plants / plasma membrane / PLASMA MEMBRANES / Ruthenium / Signal transduction / STRONTIUM / THEORY / Vacuoles / VIA BIOQUIMICA DEL METABOLISMO / VOIE BIOCHIMIQUE DU METABOLISME