Letter

Nature 457, 1007-1011 (19 February 2009) | doi:10.1038/nature07603; Received 29 August 2008; Accepted 31 October 2008; Published online 21 December 2008

Nodal signalling is involved in left–right asymmetry in snails

Cristina Grande1,2,3 & Nipam H. Patel1,2,3

  1. Department of Molecular and Cell Biology,
  2. Department of Integrative Biology, and,
  3. Center for Integrative Genomics, University of California, Berkeley, California 94720-3200, USA

Correspondence to: Nipam H. Patel1,2,3 Correspondence and requests for materials should be addressed to N.H.P. (Email: nipam@uclink.berkeley.edu).

Many animals display specific internal or external features with left–right asymmetry. In vertebrates, the molecular pathway that leads to this asymmetry uses the signalling molecule Nodal, a member of the transforming growth factor-beta superfamily1, which is expressed in the left lateral plate mesoderm2, and loss of nodal function produces a randomization of the left–right asymmetry of visceral organs3, 4. Orthologues of nodal have also been described in other deuterostomes, including ascidians and sea urchins5, 6, but no nodal orthologue has been reported in the other two main clades of Bilateria: Ecdysozoa (including flies and nematodes) and Lophotrochozoa (including snails and annelids). Here we report the first evidence for a nodal orthologue in a non-deuterostome group. We isolated nodal and Pitx (one of the targets of Nodal signalling) in two species of snails and found that the side of the embryo that expresses nodal and Pitx is related to body chirality: both genes are expressed on the right side of the embryo in the dextral (right-handed) species Lottia gigantea and on the left side in the sinistral (left-handed) species Biomphalaria glabrata. We pharmacologically inhibited the Nodal pathway and found that nodal acts upstream of Pitx, and that some treated animals developed with a loss of shell chirality. These results indicate that the involvement of the Nodal pathway in left–right asymmetry might have been an ancestral feature of the Bilateria.

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