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Timing and mechanism of the initial cue establishing handed left–right asymmetry in Caenorhabditis elegans embryos
Author(s) -
Schonegg Stephanie,
Hyman Anthony A.,
Wood William B.
Publication year - 2014
Publication title -
genesis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.093
H-Index - 110
eISSN - 1526-968X
pISSN - 1526-954X
DOI - 10.1002/dvg.22749
Subject(s) - cleavage (geology) , caenorhabditis elegans , embryo , cell division , intracellular , biology , asymmetry , asymmetric cell division , microbiology and biotechnology , cleavage furrow , polarity (international relations) , cell , cytokinesis , genetics , physics , gene , paleontology , quantum mechanics , fracture (geology)
Summary By the six‐cell stage, embryos of Caenorhabditis elegans are morphologically L–R asymmetric with an invariant handedness that persists throughout development. We used intracellular markers to ask whether breaking of L–R symmetry could be observed at earlier stages. Observation of two‐ to three‐cell embryos carrying intracellular markers indicated that L–R symmetry is broken concomitantly with establishment of D–V axis polarity during division of the anterior AB cell. The AB cleavage furrow initiates asymmetrically and always from the left, suggesting L–R differences in the AB cell cortex. An invariantly handed cortical rotation observed earlier during first cleavage implies that the one‐cell embryo has an intrinsic chirality. We propose that L–R differences in the cortex could result from mechanical forces on asymmetric components of a chiral cortical network during the off‐axis elongation of the AB‐cell spindle prior to AB cleavage. genesis 52:572–580, 2014. © 2014 Wiley Periodicals, Inc.