The technology, called a chromatin array, was developed by researchers at UT Southwestern Medical Center at Dallas and is described in the July issue of the journal Genome Research.

DNA, which contains the genetic instructions needed to make a human or any other life form, is a long molecule that is tightly compacted in a cell's nucleus. Various pieces of DNA are constantly being compressed and expanded like the folds of an accordion as a cell responds to its changing needs.

When the DNA relaxes, or expands, proteins called transcription factors gain access to the genetic code to "read" its instructions for making a molecule called RNA, which in turn makes other proteins that carry out life's essential functions, from immune response and muscle contraction to cholesterol and hormone regulation.

When DNA is highly compacted, like a closed accordion, it's not as accessible to transcription proteins, and cannot make RNA, said Dr. Harold "Skip" Garner, professor of biochemistry and internal medicine at UT Southwestern and senior author of the study.

Using the chromatin array, UT Southwestern researchers can detect the relative compactness of several stretches of DNA at a time with very high resolution, allowing them to determine which genes have the propensity for making RNA. They found that for many genes, but not all, the more open the DNA is, the more RNA is produced.

"The interesting genes are the ones that don't behave this way," Dr. Garner said.

Exactly what controls compaction and expansion of DNA is still under scientific debate. In their next set of experiments, Dr. Garner and his team will apply various drugs such as those used in cancer therapy to cells in
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Contact: Amanda Siegfried
Amanda.siegfried@utsouthwestern.edu
214-648-3404
UT Southwestern Medical Center
8-Jul-2004