Scientists Uncover How Flatworms Regrow Heads

Japanese researchers have identified the molecular cues that enable decapitated flatworms to regrow heads.

Asian Scientist (Jul. 26, 2013) – Japanese researchers have identified the molecular cues that enable decapitated flatworms to regrow heads. Their work is one of three independent studies of planarian regeneration that were published in Nature this week.

Planarians are flatworms that are known for their regenerative capabilities. However, whereas some planarian species can regenerate a whole individual from a head or tail fragment, others can only regenerate tails.

By comparing planarian species that have full regeneration with species that have partial regeneration, the three groups of researchers have independently uncovered the exact mechanisms that allow regeneration to happen.

Each of the studies showed that tweaking a specific signaling pathway can promote regrowth of heads in planarians with limited regenerative capacities.

In one of the studies, Yoshihiko Umesono and co-workers showed that the interplay between two signaling pathways (ERK and Wnt/beta-catenin) creates a gradient that selects for regrowth of either a head or a tail, depending on where the injury lies.

They suggest that the balance between these signalling pathways may vary among planarian species, explaining why some species cannot regenerate heads.

They demonstrated that Wnt/beta-catenin signaling interferes with head regeneration by showing that inhibition of this signalling activity enables head regrowth in a planarian species that otherwise cannot regenerate heads.

Similar conclusions were made in the other two independent studies. Together, all three studies reveal that manipulating a single signalling pathway can reverse the evolutionary loss of regenerative potential.

The article can be found at: Umesono et al. (2013) The Molecular Logic For Planarian Regeneration Along The Anterior–Posterior Axis.

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Source: Nature; Image: csolakbiology/Creative Commons.
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