ON THE SIGNAL-TRANSDUCTION CHAINS OF TWO Pfr- MEDIATED SHORT-TERM PROCESSES: INCREASE OF ANCHORAGE and MOVEMENT OF Mougeotia CHLOROPLASTS |
| |
| Authors: | Ekkehard,Schonbohm ,Elfriede,Schö nbohm Jens,Meyer-Wegener |
| |
| Affiliation: | Photobiology Department of Botany-FB 17, University of Marburg, Auf den Lahnbergen, D-3550 Marburg, W. Germany |
| |
| Abstract: | Abstract— We examined two published hypotheses on the signal-transduction chain of the light-oriented chloroplast movements in the fresh-water alga Mougeotia. One hypothesis postulates a Ca2+-influx controlled by a tetrapolar gradient of phytochrome in its far-red light absorbing form (Pfr). The other hypothesis postulates anchorage sites for actin-filaments even at those areas of the plasmalemma where phytochrome is in its inactive form (Pr). Calmodulin and Ca2+-sequestering vesicles are assumed to be essential links of this transduction chain.
To test these hypotheses we have studied the effects of Ca2+-entry blockers, Ca2+ deficiency and calmodulin antagonists on chloroplast movements and on chloroplast anchorage. None of our results support the Ca2+/calmodulin hypotheses mentioned above. The results and their implications (with regard to the role of Ca2', calmodulin and anchorage sites) are discussed. |
| |
| Keywords: | |
|
|
