Thaindian News

Washington, May 13 (IANS) A single adult cell from one of the most impressive masters of regeneration in the animal kingdom - the planarian - is all it takes to build a completely functional new worm, researchers say.

Planarian is the common name given to many non-parasitic flatworms of Turbellaria class. They are common to many parts of the world, living in both saltwater and freshwater ponds and rivers.

The study provides the first hard evidence that adult planarians harbour pluripotent stem cells - cells capable of producing the diverse range of tissue types necessary to build a complete animal.

Distributed throughout the worm body, the newfound cells appear to have the same all-purpose qualities as embryonic stem cells. Such cells are essential for supplying the rapidly diversifying cells in a developing embryo, but usually disappear after the earliest stages of development.

This is the first time pluripotent stem cells have been identified in an adult animal, according to Peter Reddien, the Howard Hughes Medical Institute early career scientist who led the study, reports the journal Science.

A new flatworm, complete with skin, nervous system, primitive eyes, gut, muscle, and internal organs, can emerge from a body fragment hundreds of times smaller than the match-head sized original, according to a Howard Hughes statement.

But precisely how the worms rebuild themselves cell-by-cell has been elusive. Massachusetts Institute of Technology (MIT) colleagues Daniel Wagner, Irving Wang and Reddien conducted a study in which they exposed worms to ionizing radiation, destroying cells’ ability to divide.

They used a dose of radiation low enough to let some of these survive. They then sorted through the cells to find neoblasts, cells still capable of dividing.