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First published online June 23, 2006; 10.1104/pp.106.080168 Plant Physiology 141:1591-1603 (2006) © 2006 American Society of Plant Biologists Imaging of Dynamic Secretory Vesicles in Living Pollen Tubes of Picea meyeri Using Evanescent Wave Microscopy1,[W] amaj ek Balu ka
Key Laboratory of Photosynthesis and Molecular Environment Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China (X.W., Q.W., X.L., X.S., M.Z., J.L.); Graduate School of the Chinese Academy of Sciences, Beijing 100049, China (X.W., Q.W., X.L., M.Z.); Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China (Y.T.); Institute of Cellular and Molecular Botany, Department of Plant Cell Biology, Rheinische Friedrich-Wilhelms-University Bonn, D53115 Bonn, Germany (J.
Evanescent wave excitation was used to visualize individual, FM4-64-labeled secretory vesicles in an optical slice proximal to the plasma membrane of Picea meyeri pollen tubes. A standard upright microscope was modified to accommodate the optics used to direct a laser beam at a variable angle. Under evanescent wave microscopy or total internal reflection fluorescence microscopy, fluorophores localized near the surface were excited with evanescent waves, which decay exponentially with distance from the interface. Evanescent waves with penetration depths of 60 to 400 nm were generated by varying the angle of incidence of the laser beam. Kinetic analysis of vesicle trafficking was made through an approximately 300-nm optical section beneath the plasma membrane using time-lapse evanescent wave imaging of individual fluorescently labeled vesicles. Two-dimensional trajectories of individual vesicles were obtained from the resulting time-resolved image stacks and were used to characterize the vesicles in terms of their average fluorescence and mobility, expressed here as the two-dimensional diffusion coefficient D2. The velocity and direction of vesicle motions, frame-to-frame displacement, and vesicle trajectories were also calculated. Analysis of individual vesicles revealed for the first time, to our knowledge, that two types of motion are present, and that vesicles in living pollen tubes exhibit complicated behaviors and oscillations that differ from the simple Brownian motion reported in previous investigations. Furthermore, disruption of the actin cytoskeleton had a much more pronounced effect on vesicle mobility than did disruption of the microtubules, suggesting that actin cytoskeleton plays a primary role in vesicle mobility.
1 This work was supported by the National Science Fund of China for Distinguished Young Scholars (grant no. 30225005) and a grant for general program (no. 30570100), together with grants from Deutsche Forschungsgemeinschaft (no. SA 1564/21 to J. .); from EU Research Training Network TIPNET (project no. HPRNCT200200265) obtained from Brussels, Belgium; from Slovak grant agency APVV (no. APVT51002302; Bratislava, Slovakia); from Slovak grant agency VEGA (no. 2/5085/25; Bratislava, Slovakia); and from Deutsches Zentrum für Luft- und Raumfahrt (Bonn). The author responsible for distribution of materials integral to the findings presented in this article in accordance with the policy described in the Instructions for Authors (www.plantphysiol.org) is: Jinxing Lin (linjx{at}ibcas.ac.cn). [W] The online version of this article contains Web-only data. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.106.080168. * Corresponding author; e-mail linjx{at}ibcas.ac.cn; fax 00861062590833. Received March 15, 2006; returned for revision June 6, 2006; accepted June 8, 2006. This article has been cited by other articles:
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