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Curr Biol 2016 Mar 07;265:654-60. doi: 10.1016/j.cub.2015.12.071.
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Formin Is Associated with Left-Right Asymmetry in the Pond Snail and the Frog.

Davison A , McDowell GS , Holden JM , Johnson HF , Koutsovoulos GD , Liu MM , Hulpiau P , Van Roy F , Wade CM , Banerjee R , Yang F , Chiba S , Davey JW , Jackson DJ , Levin M , Blaxter ML .

While components of the pathway that establishes left-right asymmetry have been identified in diverse animals, from vertebrates to flies, it is striking that the genes involved in the first symmetry-breaking step remain wholly unknown in the most obviously chiral animals, the gastropod snails. Previously, research on snails was used to show that left-right signaling of Nodal, downstream of symmetry breaking, may be an ancestral feature of the Bilateria [1 and 2]. Here, we report that a disabling mutation in one copy of a tandemly duplicated, diaphanous-related formin is perfectly associated with symmetry breaking in the pond snail. This is supported by the observation that an anti-formin drug treatment converts dextral snail embryos to a sinistral phenocopy, and in frogs, drug inhibition or overexpression by microinjection of formin has a chirality-randomizing effect in early (pre-cilia) embryos. Contrary to expectations based on existing models [3, 4 and 5], we discovered asymmetric gene expression in 2- and 4-cell snail embryos, preceding morphological asymmetry. As the formin-actin filament has been shown to be part of an asymmetry-breaking switch in vitro [6 and 7], together these results are consistent with the view that animals with diverse body plans may derive their asymmetries from the same intracellular chiral elements [8].

PubMed ID: 26923788
PMC ID: PMC4791482
Article link: Curr Biol
Grant support: [+]

Species referenced: Xenopus laevis
Genes referenced: diaph1 fmn1 nodal nodal1 snai1 twist1

Article Images: [+] show captions
References [+] :
Blum, The evolution and conservation of left-right patterning mechanisms. 2014, Pubmed, Xenbase