Just as libraries are organized in a manner to facilitate accessing the vast amounts of information contained in their volumes when needed, so too are mammalian genomes. The means by which this vast array of genetic information is ordered, accessed and "read" within the cell's nucleus is a multi-layered puzzle that continues to drive scientific investigation.

Stephen Krawetz, Charlotte B. Failing Professor of Fetal Therapy and Diagnosis, recently published a paper in the Proceedings of the National Academy of Sciences that describes how our genes are selected for experession.

Published online May 1, the paper asked, How are genes selected for expression in a cell? One of the key switches in determining a cells' destiny has been identified utilizing the protamine genes as the model system, Krawetz said. These genes are found in every cell, yet are only expressed in the male germline.

The first step in the process involves the physical relaxation of the region of DNA surrounding the gene, the domain, which proceeds much like unwinding a telephone cord. Curiously, a series of interactions between topoisomerases, enzymes responsible for relaxing chromatin, and the nuclear matrix attachment regions adjacent to the domain appear as the initial interactions that kick-start the selective process that sets the tone for the ex pression of a cell's genetic repertoire.

To read the full paper, "Decondensing the protamine domain for transcription," please visit http://www.pnas.org/cgi/content/abstract/0700076104v1. Dr. Krawetz is a member of the WSU Department of Obstetrics & Gynecology as well as the Center for Molecular Medicine & Genetics.