ABOVE: A flatworm whose “degrowing” phase was suppressed towers over a control worm

Repressing a gene in planarian flatworms (Schmidtea mediterranea) that prevents stem cells from producing a key growth factor results in the animals doubling in size, report the authors of a study published on January 20 in Current Biology.

The flatworms are known for their extraordinary ability to regenerate themselves after almost every kind of injury, a process that involves a growing phase followed by a “degrowing” phase during which the worm is scaled back to restore its proportionality. It was the rescaling phase that the researchers blocked in the study.

“These worms have essentially discovered a natural form of regenerative medicine through their evolution,” says Christian Petersen, who studies regeneration at Northwestern University and is coauthor of the paper, in a university press release. “Planarians can regenerate their whole...

E.G. Schad, C.P. Petersen, “STRIPAK limits stem cell differentiation of a WNT signaling center to control planarian axis scaling,” Current Biology, doi:10.1016/j.cub.2019.11.068, 2020.

Amy Schleunes is an intern at The Scientist. Email her at aschleunes@the-scientist.com.

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