( effectively become tiny pills-five to ...)Researchers feed tiny pills of RNA to planarians to identify genes essential for regeneration

Sánchez Alvarado and Helen Hay Whitney Foundation postdoctoral fellow Peter W. Reddien, Ph.D., silenced and screened 1,065 planarian genes with RNAi. Specific defects were associated with 240 of the genes that were silenced. About 85 percent (204) of the 240 genes are shared by the genomes of other species, including humans, according to Sánchez Alvarado.

The researchers found that 145 of the silenced genes affect both regeneration and tissue loss and replacement. Some of the genes were essential to homeostasis, but not regeneration, and 35 genes were found to be essential to regeneration, but not homeostasis.

"This tells us that separate genetic pathways for regeneration and homeostasis must exist," Sánchez Alvarado said. "It's a huge step forward for us and opens the possibility of systematic molecular studies to find the genetic cause of regenerative processes in animals."

Silencing planarian genes may also help in studying human disease. Thirty-eight of the genes Sánchez Alvarado and his team silenced are related to human genes associated with diseases, such as ataxia (inability to coordinate muscular movements), bradyopsia (slow vision), and cancer. Only eight of those genes have a corresponding knockout gene in mice. This means researchers may be able to use planarians to learn about human diseases that can't be studied in other animal models.

Another 35 of the silenced genes may shed light on the parasitic platyhelminthes, such as Schitosoma mansoni, which cause disease in millions of people. The genes identified by the U researchers may be required for the survival of the parasites.

"Considering such pathogens are estimated to cause disease in nearly 300 million people throughout the world, these genes might m
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Source:University of Utah Health Sciences Center