Ancient Resilience

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Categories : Evolution

Editor : MikeGene

published: mardi 14 novembre 2006 4:46:06

"Interestingly, some species have the ability to regenerate appendages, while even fairly closely related species do not," Poss added. "This leads us to believe that during the course of evolution, regeneration is something that has been lost by some species, rather than an ability that has been gained by other species. The key is to find a way to 'turn on' this regenerative ability."

Scientists previously had suspected that zebrafish regenerated their heart tissue by the direct division of existing cardiac muscle cells adjacent to the injury, Poss said.

However, Poss and colleagues found that the process more closely resembles what happens when a salamander regenerates a lost limb. In the salamander, the site of injury becomes the gathering point for a mass of undifferentiated stem, or progenitor, cells, which are immature cells with the potential to be transformed into other cell types. This mass of undifferentiated cells is known as a blastema. As the progenitor cells receive the correct biochemical cue, they turn into distinct cell types, such as bone, muscle and cartilage, to form the new limb.

Evolution,