The pollen tube exhibits cytoplasmic streaming of organelles, which is dependent on the actinmyosin system. Although microtubule-based motors have been also identified in the pollen tube, many uncertainties exist on their role in organelle transport. As part of our attempt to understand the role of microtubule-based movement in the pollen tube of tobacco, we investigated the cooperation between microtubules and actin filaments in the transport of mitochondria and Golgi vesicles, which are distributed differently in the growing pollen tube. The analysis was performed using in vitro motility assays in which organelles move along both microtubules and actin filaments. Results indicated that the movement of mitochondria and Golgi vesicles is slow and continuous along microtubules but fast and irregular along actin filaments. In addition, the presence of microtubules in the motility assays force organelles to use lower velocities. Actin- and tubulin-binding tests, immunoblotting, and immunogold labelling indicated that different organelles bind to identical myosins but associate with specific kinesins. We found that a 90-kD kinesin (previously known as 90-kD ATP-MAP) is associated with mitochondria but not with Golgi vesicles, whereas a 170-kD myosin is distributed on mitochondria and other organelle classes. In vitro and in vivo motility assays indicate that microtubules and kinesins decrease the speed of mitochondria thus contributing to their positioning in the pollen tube.
|Titolo:||Microtubule and actin filament dependent motors are distributed on pollen tube mitochondria and contributed differently to their movement.|
|Citazione:||Romagnoli, S., Cai, G., Faleri, C., Yokota, E., Shimmen, T., & Cresti, M. (2007). Microtubule and actin filament dependent motors are distributed on pollen tube mitochondria and contributed differently to their movement. PLANT AND CELL PHYSIOLOGY, 48(2), 345-361.|
|Appare nelle tipologie:||1.1 Articolo in rivista|