Bar Harbor, Maine -- Proteins called H2AX act as "first aid" to DNA, among other roles. For the first time, scientists using the world's most powerful light microscope (the only one of its kind in the Americas) have seen how H2AX is distributed in the cell nucleus: in clusters, directing the first aid/repair after DNA injuries to the region where it is really needed.
Many biological processes lie out of the visual reach of scientists. The benefits of high-resolution electron microscopy are often offset by disruptive sample preparation requirements. Light microscopy allows easier sample prep and observations of living cells, but it has limited resolution. By manipulating how light waves behave, however, biophysicists are expanding the limits of light microscopy, and one of the latest advances--the 4Pi microscope--provides never-before-seen views of cellular components, including structures within the nucleus.
In a paper published in the Proceedings of the National Academy of Sciences, Joerg Bewersdorf of the Institute for Molecular Biophysics at The Jackson Laboratory, with collaborators Brian Bennett of the UMass Medical School and Leica Microsystems and Kendall Knight of the UMass Medical School, used the 4Pi microscope to examine the cellular response to a type of severe damage to the genetic material, DNA double-strand breaks. Such breaks provoke a rapid and highly coordinated series of events to identify and repair the damage. The response is critical, and there is an increased risk for cancer, developmental abnormalities and immunological problems when components of the repair processes are defective.
Traditional microbiological and genetics techniques can shed light on the molecular pathways of repair, but they don't address the astonishingly complex three-dimensional structure of the genetic material in the nucleus. 4Pi microscopy allows researchers to actually see the response in three dimensions, at resolut
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Contact: Joyce Peterson
joyce.peterson@jax.org
207-288-6058
Jackson Laboratory
13-Nov-2006