Today Nature magazine is publishing an article led by developmental biologist Elly Tanaka, (from the Center for Regenerative Therapies at the Dresden University of Technology), explaining the mechanics of salamander limb regeneration. Elly Tanaka genetically engineered an axolotl salamander with a green fluorescent protein in all cells of the body, which allowed her to visually trace the fate of cells during regeneration. Her discovery was quite startling and already the science blogging community is buzz with excitement.
Scientists have long observed the salamander's unique ability to regenerate not only limbs, but jaws, skin, and even parts of brain and spinal chord. Scientists originally theorized that regeneration occurs because cells at the amputation site lose their identities and turn back their developmental clocks and become "pluripotent" stem cells (capable of developing into many cell types in the body), which then recreate the lost limb.
This study explains that cells at the amputation site retain memories of their identities and regenerate to form the same type of tissue in the replacement limb. The concept of cellular memory is still wearily approached by scientists and researchers, but in the case of the salamander, it's what makes regeneration possible. It also means that instead of stem cells, the amputated cells simply reproduce more of themselves; muscles grow from muscles, and bones from bones.
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