Telltale moss( Hikers know that moss on a tree trun...)

Hikers know that moss on a tree trunk always points north. According to new research by Israeli and German scientists, this ancient plant may also provide a new "compass" for stem cell research, telling scientists how better to program stem cells for medical purposes.

Dr. Nir Ohad of Tel Aviv University's Department of Plant Sciences and Prof. Ralf Reski of the University of Freiburg have discovered a new use for the Polycomb group proteins (PcG) found in moss. They reported their findings recently in the journal Development. PcG proteins play an important role in telling stem cells how to develop, they believe. The research is being funded by the German-Israeli Foundation.

Moss is a kind of plant that shares basic development processes with those found in humans. "We may not have found the switch that turns stem cells into tissue," comments Dr. Ohad, "but we have found a key component which makes this switch work."

Stopping the runaway gene

In their new paper, the researchers describe an ancient mechanism that alters the way DNA organizes inside the cell nucleus, which in turn, affects gene expression. This finding has important implications in stem cell therapies, which can go awry if implanted stem cells aren't reprogrammed properly.

The researchers examined the "central regulatory function" of the PcG complex and how it programs an organism's development, including the first divisions of cells as a new organism is born. Insights from this research have implications for plant and human development alike, and with time could be applied to cancer research. "As far as we know, there are some instances in cancer where the cellular mechanisms are defective or impaired," Dr. Ohad says. "When this happens, it can lead to the misregulation of the genetic code, which can then lead to the breakdown of a healthy cell."

He adds that this "switch," which ensures the proper development of the organism, emerg
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