Intrinsic chiral properties of the Xenopus egg cortex: An early indicator of left-right asymmetry

Michael Danilchik, Elizabeth E. Brown, Kristen Riegert

Research output: Contribution to journalArticle

76 Citations (Scopus)

Abstract

Vertebrate embryos define an anatomic plane of bilateral symmetry by establishing rudimentary anteroposterior and dorsoventral (DV) axes. A left-right (LR) axis also emerges, presaging eventual morphological asymmetries of the heart and other viscera. In the radially symmetric egg of Xenopus laevis, the earliest steps in DV axis determination are driven by microtubule-dependent localization of maternal components toward the prospective dorsal side. LR axis determination is linked in time to this DV-determining process, but the earliest steps are unclear. Significantly, no cytoskeletal polarization has been identified in early embryos capable of lateral displacement of maternal components. Cleaving Xenopus embryos and parthenogenetically activated eggs treated with 2,3-butanedione monoxime (BDM) undergo a dramatic large-scale torsion, with the cortex of the animal hemisphere shearing in an exclusively counterclockwise direction past the vegetal cortex. Long actin fibers develop in a shear zone paralleling the equator. Drug experiments indicate that the actin is not organized by microtubules, and depends on the reorganization of preexisting f-actin fibers rather than new actin polymerization. The invariant chirality of this drug response suggests a maternally inherited, microfilament-dependent organization within the egg cortex that could play an early role in LR axis determination during the first cell cycle. Consistent with this hypothesis, brief disruption of cortical actin during the first cell cycle randomizes the LR orientation of tadpole heart and gut.

Original languageEnglish (US)
Pages (from-to)4517-4526
Number of pages10
JournalDevelopment
Volume133
Issue number22
DOIs
StatePublished - Nov 2006

Fingerprint

Xenopus
Ovum
Actins
Embryonic Structures
Microtubules
Cell Cycle
Mothers
Viscera
Xenopus laevis
Actin Cytoskeleton
Polymerization
Pharmaceutical Preparations
Eggs
Larva
Vertebrates

Keywords

  • Actin
  • Axis formation
  • Cytoskeleton
  • Egg
  • Left-right asymmetry
  • Microtubule
  • Xenopus laevis

ASJC Scopus subject areas

  • Anatomy
  • Cell Biology

Cite this

Intrinsic chiral properties of the Xenopus egg cortex : An early indicator of left-right asymmetry. / Danilchik, Michael; Brown, Elizabeth E.; Riegert, Kristen.

In: Development, Vol. 133, No. 22, 11.2006, p. 4517-4526.

Research output: Contribution to journalArticle

Danilchik, Michael ; Brown, Elizabeth E. ; Riegert, Kristen. / Intrinsic chiral properties of the Xenopus egg cortex : An early indicator of left-right asymmetry. In: Development. 2006 ; Vol. 133, No. 22. pp. 4517-4526.
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