( University of Utah researchers-feeding ...)Researchers feed tiny pills of RNA to planarians to identify genes essential for regeneration

In pinpointing the genes, the U School of Medicine researchers have established the planarian as a genetically sound model for human biology, to take its place alongside Drosophila (fruit flies), C.elegans (another worm), zebrafish, and mice.

The study, to be published in the May issue of Developmental Cell, employed the first large-scale use of RNA interference (RNAi) to silence planarian genes to identify their role in the worm's biology, according to Alejandro Sánchez Alvarado, Ph.D., principal investigator and U medical school associate professor of neurobiology and anatomy. The U team's work shows that planarian genes can be selectively manipulated to study some of the most basic and important areas of biological research: stem cells, homeostasis (tissue loss and replacement), regeneration, and disease.

"Planarian biology has much in common to the biology that you and I share," said Sánchez Alvarado, who last month was appointed a Howard Hughes Medical Institute investigator. "This work opens a whole new window to study aspects of human biology that are barely accessible today."

The planarians used in these studies, also called flatworms, live in fresh water and have a singular 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. Researchers know that planarian stem cells, called neoblasts, play a central role in both regeneration and homeostasis. But how they do that has remained shrouded in mystery.

Sánchez Alvarado and his research associates used bacteria to synthesize double-stranded RNA that silences planarian genes. The bacteria
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Source:University of Utah Health Sciences Center