ISSN:
1432-2048
Keywords:
Key words: Chlorotetracycline
;
Chara
;
Cytoplasmic calcium
;
Light (membrane potential)
;
Photosynthesis
;
Protoplasmic streaming
Source:
Springer Online Journal Archives 1860-2000
Topics:
Biology
Notes:
Abstract. The fluorescent dye chlorotetracycline was used to study the relationship between the light-induced decrease in cytosolic free calcium concentration, [Ca2+]c, and its effect on ion transport at the plasma membrane in the giant cells of Chara corallina Klein ex Willd. A kinetic analysis of the simultaneously measured light-induced changes in membrane potential and in [Ca2+]c led to the same time constant of about 40 s. The reversal potential of the light effect on membrane potential was in agreement with the dominant role of a K+ channel in the plasma membrane. Thus, the experiments reported here provide evidence for the following light-driven signal transduction chain from the chloroplasts to K+ transport of the plasma membrane: (i) light causes an uptake of Ca2+ into the chloroplasts, (ii) this causes a decrease in cytosolic [Ca2+]c, (iii) this leads to a decrease in the activity of a K+ channel. The results also initiated a re-analysis of previously published data of the light effect on the velocity of cytosolic streaming and supported the hypothesis that Ca2+ fluxes coming out of the chloroplasts upon darkening cause a Ca2+-induced phosphorylation of myosin, which slows down cytoplasmic streaming.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/s004250050454
