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Abstract Detail


Cytoskeleton Structure and Dynamics

Parris, Colleen [1], Lovy-Wheeler, Alenka [2], Luetz-Meindl, Ursula [3], Hepler, Peter K. [4].

Osmium Tetroxide Degrades the Actin Cytoskeleton in Lily Pollen Tubes.

The actin cytoskeleton is essential for pollen tube growth. Its structure consists of longitudinally oriented bundles in the shank and a prominent cortical fringe in the apex of the pollen tube. However, actin structure at the electron microscopic level has not been resolved. Because osmium tetroxide (OsO4) degrades filamentous actin (F-actin) in other systems, we have tested its effect on actin in lily pollen tubes. Pollen tubes were fixed with glutaraldehyde and ethylene glycol bis[sulfosuccinimidylsuccinate](sulfo-EGS), which cross-links and stabilizes F-actin. Staining with Alexa Fluor 488 phalloidin reveals F-actin, including the cortical actin fringe. To examine the effects of OsO4, cells were exposed to varying concentrations (1.0-0.01%) either before or after staining with phalloidin. Analysis by fluorescence microscopy reveals that 1% OsO4 degrades the actin in the pollen tube. Fluorescence is evident but actin filaments are not clearly delineated; notably the prominent cortical actin fringe is not detected. Lower concentrations of OsO4 cause less damage, but some degradation occurs at 0.01%. By comparison to earlier studies, plant F-actin appears to be more sensitive to OsO4 than animal actin, perhaps due to the lack of tropomyosin. Steps are currently underway to generate contrast so that the full spectrum of F-actin can be visualized at the electron microscope level.


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1 - University of Massachusetts, Biology, 611 North Pleasant Street, Amherst, MA, 01003, USA
2 - Tufts Medical School, Department of Neuroscience
3 - University of Salzburg, Salzburg, Austria, Institute of Plant Physiology
4 - University of Massachusetts, Biology

Keywords:
actin
osmium.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P23002
Abstract ID:242


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