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General Comment |
Gore AV, et al 2002 reported that the localization of transcripts of the Zebrafish morphogen Squint
is dependent on egg activation and the microtubule cytoskeleton.
The generation of polarity and patterning in multicellular organisms depends
in part on the asymmetric localization of molecules to specific subdomains
within a cell. Localized transcripts for several molecules are known to be
required for patterning oocytes and embryos in Drosophila as well as
Caenorhabditis clegans. The authors describe the localization of transcripts
encoding the nodal-related morphogen, Squint (sqt), in zebrafish oocytes and
early embryos, and the mechanisms by which sqt RNA is localized. sqt
transcripts are uniformly distributed in oocytcs through all stages of
oogenesis. Upon egg activation, sqt RNA is localized to the blastoderm, and
excluded from the yolk cell. The mechanism of sqt RNA transport was examined
using cytoskeletal inhibitors. Disruption of actin microfilaments by treatment
with latrunculin A does not alter the localization of sqt RNA to the
blastoderm. However, disruption of the microtubule cytoskeleton by treatment
with nocodazole affects sqt RNA localization. These results indicate that sqt
transcripts are translocated by an RNA localization pathway which is initiated
upon egg activation, and that sqt RNA localization through this pathway is
mediated via the microtubule cytoskeleton.
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