Modulation of chloroplast movement in the green alga Mougeotia by the Ca2+ ionophore A23187 and by calmodulin antagonists.
The Ca2+ ionophore A23187 can induce chloroplast rotation within a single nonirradiated Mougeotia cell.  The induced turning was dependent on the position of ionophore application and Ca2+ in the external medium.  The role of calmodulin in mediating light-induced chloroplast rotation in the alga Mougeotia was investigated by using the paired calmodulin-antagonist drugs W5-W7 and W12-W13.  In each pair, the antagonist with the greater affinity for calmodulin had the greater inhibitor effect on the phytochrome-controlled light response.  These results support the hypothesis that calcium functions as a chemical messenger to couple the stimulus of phytochrome photoactivation with physiological responses in plants.
Serlin
B S
BS
Department of Botany, The University of Texas, Austin 78713, USA.
Roux
S J
SJ
D008841:Actin Cytoskeleton / Q000502:physiology; D000001:Calcimycin / Q000494:pharmacology*; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D002147:Calmodulin / Q000037:antagonists & inhibitors* / Q000378:metabolism / Q000502:physiology; D000460:Chlorophyta / Q000187:drug effects / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D002736:Chloroplasts / Q000187:drug effects* / Q000378:metabolism / Q000502:physiology* / Q000528:radiation effects; D007476:Ionophores / Q000494:pharmacology*; D008027:Light; D010834:Phytochrome / Q000502:physiology / Q000528:radiation effects; D012399:Rotation; D015398:Signal Transduction / Q000502:physiology; D014634:Valinomycin / Q000494:pharmacology
D002147:Calmodulin; D007476:Ionophores; D010834:Phytochrome; D014634:Valinomycin; D000001:Calcimycin; D002118:Calcium