Many organisms have the innate capability to regenerate lost body parts. Plants do it all the time, and animals such as salamanders can regenerate a missing tail, legs, even eyes! Among invertebrates (sponges, Hydra, Starfish) it is more common, and it gets less and less common as we move up the complexity scale. Why and how it happens, and why it is rare in higher animals, is still a mystery. One fundamental quest is to find the genes that control this process of regeneration. Now University of Utah researchers have successfully identified many such genes in a flatworm, called Planarian (Schmidtea mediterranea). Interestingly, it shares many of genes with us humans (Yay evolution :) ), and therefore this work can uncover clues to our abilities to regenerate :D.

Planarian (Courtesy: John Burroughs School)Planarians have a great ability to regenerate. Chop one in half, and two new worms grow. Their ability to regenerate is so prolific that a tissue fragment only 1/279th of the worm’s length can grow into a new planarian. Planarian stem cells, called neoblasts, play a central role in this process. But this process was shrouded in mystery, until now.
Sánchez Alvarado and Peter W. Reddien first inserted RNA strands that shut off a particular planarian gene into some bacterial DNA. Next, they fed such bacteria-laced food to the planarian. Predictably enough, soon the planarian genome was riddled with this RNA, which effectively shut down the expression of this particular planarian gene. By repeating the process with different RNA strands that shut off different planarian genes, the researchers were able to map the behavior of the genes by observing the defects they introduce in the planarian 'children'.
The researchers found that out of 1,065 planarian genes, 145 affect both regeneration and tissue loss and replacement. 38 of these genes are related to human genes associated with diseases, such as ataxia (inability to coordinate muscular movements), bradyopsia (slow vision), and cancer!! This makes the planarian an ideal model to test human diseases, and perhaps to find a cure for the various ailments that affect us.
Scientists should now be able to shut off genes in planarian, and tinker with them to see how genetic expression in planarian contribute to its regenerative capabilities. This can lead to new treatments to terrible diseases in the not too distant future :):).