Probing the interactions between organelles and cytoplasm
using targeted aequorins
Trewavas, A.J., Van der Luit, A., Haley, A., Knight, M., Olivari, C.
Institute of Cell and Molecular Biology, University of Edinburgh, Mayfield Road,
Edinburgh EH9 3JH, Scotland
In 1991 we reported that cytosolic Ca2+ in plant cells could be reported by transforming tobacco plants with the cDNA for the Ca2+-sensitive, luminescent protein aequorin. With appropiate constructs containing specific promoters or targeting sequences, aequorin could be specifically expressed either at particular stages of cell development, in particular cell types or in specific organelles. Thus the interactions which involve the important second message Ca2+ between cells or cell compartments could be non-invasively and simply examined using several types of transformed plants containing targeted aequorins and a luminometer. To date we have targeted aequorin to nuclei, chloroplasts, ER and attached it to the vacuole membrane and the
plasma membrane. When plants are signalled by wind they transiently increase intracellular Ca2+ and increase the expression of specific genes such as calmodulin. Other experiments suggest that calmodulin gene expression is controlled by intracellular Ca2+. We have used tobacco seedlings containing nuclear targeted and cytosolic targeted aequorin to investigate the interrelationships of Ca2+ between these two cell compartments. Our results indicate that in plant cells after wind signalling the nucleus regulates Ca2+ in partial independence from the cytoplasm and that a nuclear Ca2+ pathway regulating calmodulin gene expression is likely. In contrast, with another signal, cold shock, calmodulin gene expression is primarily regulated by Ca2+ in the cytoplasm and the relationship between nucleus and cytoplasm is thus altered.
| LOCATION |
DATE |
TIME |
| Lecture Hall I |
Monday, April 6 |
03:40 pm |