Cilia are required for asymmetric nodal induction in the sea urchin embryo. Issue 1 (December 2016)

• Record Type: Journal Article
• Authors: Tisler, Matthias; Wetzel, Franziska; Mantino, Sabrina; Kremnyov, Stanislav; Thumberger, Thomas; Schweickert, Axel; Blum, Martin; Vick, Philipp
• Is Part Of: BMC developmental biology. Volume 16:Issue 1(2016)
• Page Start: 1
• Page End: 12
• Publication Date: 2016-12
• Subjects: Sea urchin -- Deuterostomes -- Left-right asymmetry -- Symmetry breakage -- Nodal -- Cilia -- Left-right organizer; Developmental biology -- Periodicals; 571.8
• DOI: 10.1186/s12861-016-0128-7
• Languages: English
• ISSNs: 1471-213X

Abstract

Abstract Background Left-right (LR) organ asymmetries are a common feature of metazoan animals. In many cases, laterality is established by a conserved asymmetric Nodal signaling cascade during embryogenesis. In most vertebrates, asymmetricnodal induction results from a cilia-driven leftward fluid flow at the left-right organizer (LRO), a ciliated epithelium present during gastrula/neurula stages. Conservation of LRO and flow beyond the vertebrates has not been reported yet. Results Here we study sea urchin embryos, which usenodal to establish larval LR asymmetry as well. Cilia were found in the archenteron of embryos undergoing gastrulation. Expression offoxj1 anddnah9 suggested that archenteron cilia were motile. Cilia were polarized to the posterior pole of cells, a prerequisite of directed flow. High-speed videography revealed rotating cilia in the archenteron slightly before asymmetricnodal induction. Removal of cilia through brief high salt treatments resulted in aberrant patterns ofnodal expression. Our data demonstrate that cilia - like in vertebrates - are required for asymmetricnodal induction in sea urchin embryos. Conclusions Based on these results we argue that the anterior archenteron represents abona fide LRO and propose that cilia-based symmetry breakage is a synapomorphy of the deuterostomes.