Left-right asymmetry: lessons from Cancún.
The satellite symposium on ''Making and breaking the left-right axis: implications of laterality in development and disease'' was held in June 2013 in conjunction with the 17th International Society for Developmental Biology meeting in Cancún, Mexico. As we summarize here, leaders in the field gathered at the symposium to discuss recent advances in understanding how left-right asymmetry is generated and utilized across the animal kingdom.
PubMed ID: 24194469
PMC ID: PMC3817937
Article link: Development.
Genes referenced: aldh1a2 arl13b ccdc28b dand5 fgf8 fn1 foxj1 foxj1.2 lefty nodal nodal1 nodal3.1 pitx2 pkd1l1 pkd2 rpsa
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|Fig. 1. Aspects of vertebrate and invertebrate LR patterning. (A) Image of a gastrulating Xenopus embryo showing the expression of foxj1 (blue), which encodes a transcription factor involved in ciliogenesis, in the superficial mesoderm. (B) The superficial mesoderm contributes to the gastrocoel roof plate (GRP; outlined), which is situated above the blastopore lip (Bp) and serves as the left-right organizer (LRO) in Xenopus embryos. (C) Magnification of the GRP area shown in B reveals the presence of cilia (black arrowheads). (D) Image of the mouse node, which serves as an LRO and is also ciliated. Cilia are labeled to show localization of the ciliary GTPase Arl13b (red) and acetylated α-tubulin (green). (E) The polycystin protein Pkd1l1 (Pkd1l1-GFP, green) also localizes to cilia (labeled with acetylated α-tubulin; red) in mouse inner medullary collecting duct cells (IMCD-3) and may repress Pkd2 activity. (F) Cross-section of a Xenopus embryo highlighting the extracellular matrix components expressed in the embryo at this stage, with fibronectin (green), laminin (red) and nuclei (DAPI, blue) labeled. The ECM may limit Nodal diffusion in the embryo. (G) In zebrafish, the Nodal ortholog southpaw (arrow) is expressed on the left (L) and induces lefty expression (asterisk) on the left side of the developing heart. (H) In chick, Nodal induces pitx2 expression (blue) on the left side of the dorsal mesentery, which is the tissue that drives leftward midgut rotation. (I) Nodal also directs the zebrafish heart tube (highlighted in blue; cardiac myosin light chain 7, myl7) to ‘jog’ to the left side of the embryo placing the atrium (A) to the left of the ventricle (V). (J-L) Drosophila genitalia rotate clockwise in wild-type embryos. The direction of rotation depends upon myosin 1D activity. Images in A-C are used courtesy of Martin Blum; D is reproduced with permission from Elsevier (Caspary et al., 2007); E is courtesy of Daniel T. Grimes and Dominic Norris; F is courtesy of Chris Wright; G and I are courtesy of Kari Baker Lenhart and Rebecca D. Burdine; H is courtesy of Natasza Kurpios; and J-L are produced courtesy of Suzanne Magali and Stéphane Noselli.|