( type of cell. And beyond that the newl...)Advance helps explain stem cell behavior

"It's clear that there is an extended sequence of steps which turn some genes on and others off, allowing a cell to become a liver cell, for instance, rather than a brain cell," said Chrissa Kioussi, an OSU assistant professor of pharmacology and co-author on the study. "We were able to use a system of microarray comparisons that monitored the expression of genes and more quickly gives us an idea of how this process is working, and how patterns of development occur."

The studies were done in embryonic spinal cord in mice, although the same process ultimately takes place during development of any organ or bodily system, the researchers said. The research identified the subset of genes involved in producing the various types of spinal cord cells ?there may be 10s to 100s of cell types just in the spinal cord. The cell types are created very quickly in early embryonic development by a pattern formation mechanism, and then mature more slowly as the central nervous system creates the functional neural circuits.

Understanding this pattern formation mechanism will be essential to the ultimate use of stem cells in medical research and disease treatment, the scientists said. Ideally, researchers would like to create a "transcriptional network model" that simulates all of the complex and interactive steps in this patterning process, Gross said.

Much of this process happens during a surprisingly short time and at very early stages of embryonic development. In mice, for instance, virtually all of the types of cells are formed in 12 days, during what would correspond to a fraction of the "first trimester" of the human gestational period, as genetic mechanisms guide the "readout" of DNA and control the formation of different types of cells. The cell types themselves are created well before they are "wired togethe
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Source:Oregon State University