ISSN:
1399-3054
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Biology
Notes:
Using roots from Arabidopsis thaliana expressing the recombinant calcium indicator aequorin, we show that NH3 uptake and alkalisation of plant cells act as a stimulus which induces transient elevations of the cytoplasmic free calcium concentration ([Ca2+]c). The magnitudes of these [Ca2+]c elevations are dependent on the concentration of the membrane permeable form, NH3, and hence, particularly dependent on the pH in the external medium. EGTA and La3+ are able to significantly suppress the [Ca2+]c transients showing that Ca2+ influx through the plasma membrane is likely to be involved. Verapamil and nifedipine had no inhibitory effects, which suggests that Ca2+ release from internal stores might not contribute significantly to the NH3-triggered [Ca2+]c response. Pre-incubation in l-methionine-dl-sulphoximine – an inhibitor of the glutamine synthetase – did not alter the NH3-induced [Ca2+]c responses at all. These results are consistent with previous studies where NH3-induced changes of cytoplasmic and vacuolar pH were investigated in maize roots. Furthermore, the similarity between the kinetics of NH3-driven cellular pH changes demonstrated in previous studies and the [Ca2+]c transients shown here suggests a direct relationship between [Ca2+]c and cellular alkalisation (cytoplasmic pH and/or vacuolar pH). However, the mechanism behind this possible causal relation remains to be elucidated.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1399-3054.2000.1100414.x
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