Open AccessMicrotubule-mediated transport of organelles and localization of β-catenin to the future dorsal side of Xenopus eggs
Author(s) -
Brian A. Rowning,
Justin Wells,
Mike Wu,
John C. Gerhart,
Randall T. Moon,
Carolyn A. Larabell
Publication year - 1997
Publication title -
proceedings of the national academy of sciences of the united states of america
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.011
H-Index - 771
eISSN - 1091-6490
pISSN - 0027-8424
DOI - 10.1073/pnas.94.4.1224
Subject(s) - microtubule , xenopus , organelle , cytoplasm , microbiology and biotechnology , anatomy , biology , biophysics , axoplasmic transport , chemistry , biochemistry , gene
The dorsal–ventral axis in frog embryos is specified during the first cell cycle, when the cortex rotates relative to the cytoplasmic core along parallel microtubules associated with the core. Cytoplasmic transfer experiments suggest that dorsal determinants are transported 90° from the vegetal pole to the dorsal equator, even though the cortex rotates only 30°. Here we show that, during rotation, small endogenous organelles are rapidly propelled along the subcortical microtubules toward the future dorsal side and that fluorescent carboxylated beads injected into the vegetal pole are transported at least 60° toward the equator. We also show that deuterium oxide, which broadens the zone of dorsalization even though it reduces the extent of rotation and is known to randomize the microtubules, also randomizes the direction of organelle transport. Moreover, β-catenin, a component of the Wnt signaling pathway that possesses dorsalizing activity inXenopus , colocalizes with subcortical microtubules at the dorsal side of the egg at the end of rotation. We propose that cortical rotation functions to align subcortical microtubules, which then mediate the transport of dorsal determinants toward their plus ends on one side of the egg.