Polarity establishment requires dynamic actin in fucoid zygotes |
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Authors: | Hable W E Miller N R Kropf D L |
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Institution: | (1) Department of Biology, University of Utah, Salt Lake City, Utah, US |
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Abstract: | Summary. Previous work has demonstrated that actin plays important roles in axis establishment and polar growth in fucoid zygotes.
Distinct actin arrays are associated with fertilization, polarization, growth, and division, and agents that depolymerize
actin filaments (cytochalasins, latrunculin B) perturb these stages of the first cell cycle. Rearrangements of actin arrays
could be accomplished by transport of intact filaments and/or by actin dynamics involving depolymerization of the old array
and polymerization of a new array. To investigate the requirement for dynamic actin during early development, we utilized
the actin-stabilizing agent jasplakinolide. Immunofluorescence of actin arrays showed that treatment with 1–10 μM jasplakinolide
stabilized existing arrays and induced polymerization of new filaments. In young zygotes, a cortical actin patch at the rhizoid
pole was stabilized, and in some cells supernumerary patches were formed. In older zygotes that had initiated tip growth,
massive filament assembly occurred in the rhizoid apex, and to a lesser degree in the perinuclear region. Treatment disrupted
polarity establishment, polar secretion, tip growth, spindle alignment, and cytokinesis but did not affect the maintenance
of an established axis, mitosis, or cell cycle progression. This study suggests that dynamic actin is required for polarization,
growth, and division. Rearrangements in actin structures during the first cell cycle are likely mediated by actin depolymerization
within old arrays and polymerization of new arrays.
Received July 15, 2002; accepted November 27, 2002; published online June 13, 2003
RID="*"
ID="*" Correspondence and reprints: Department of Biology, University of Utah, 257 South 1400 East, Salt Lake City, UT 84112-0840,
U.S.A. |
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Keywords: | : Silvetia compressa Pelvetia compressa Jasplakinolide Actin cytoskeleton Axis establishment Polar growth |
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