How Sea Stars Get Their Symmetry | Whitehead Institute

Starfish. Credit: Logan Science Journalism Program

In a paper published Nov. 4 in the journal Current Biology, Zak Swartz, a postdoctoral researcher at Whitehead Institute, along with researchers in the lab of Whitehead Institute Member Iain Cheeseman and collaborators at the Massachusetts Institute of Technology (MIT), the University of Miami, and the Marine Biological Laboratory Embryology Course delve into the origins of the initial polarity in an animal’s first cell, which establishes an axis of symmetry for the developing organism and underlies the first steps of development.

Their reveals how a specific protein, called Dishevelled, localizes in a cell to help create this polarity. All multicellular organisms begin as a single cell — the oocyte, precursor cell to the egg — which carries within it a “plan” for the fully developed, complex creature it will become. “How that multifunctional body plan is created is one of the deepest questions in developmental biology,” said Swartz. “Sea stars, and a huge diversity of other animals, have an incredibly complex body plan, none of which is possible without the polarity of the initial cell,” said Cheeseman. “This work shows how the polarity originates as early as the meiotic divisions in the developing oocyte through an unexpected strategy to break its symmetry and achieve the asymmetric distribution of developmental factors.”   .

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