Scientists at the University of North Carolina at Chapel Hill and colleagues have developed a new microscopic assay that, for the first time, allows them to see DNA breaks in chromosomes in living cells following damage to those complex, gene-filled structures.Their success is exciting because the assay should become a powerful new aid for boosting understanding of chromosome damage and how it is repaired naturally or might be repaired therapeutically, said Dr. Kerry S. Bloom, professor of biology at UNC. Chromosome damage leads to at least hundreds of fatal or debilitating illnesses."In the course of this work, we discovered that when breaks occur in either one or both strands of DNA, which is a complex, double-stranded, helical molecule, the chromosomes do not fragment,” Bloom said. “Proteins are recruited very quickly to the sites of DNA damage, and they keep the chromosome intact. This was hypothesized but never shown before. We also identified some of those specific proteins."Human cells contain an amazing amount of DNA, which produces proteins for countless tasks in the body, the scientist said. “In fact, if you took all of the DNA in your cells and stretched it out, it would go to the sun and back. That is awesome."A report on the research appears in the latest issue of the journal Current Biology. Besides Bloom, authors are Kirill Lobachev, formerly of the National Institute of Environmental Health Sciences’ Laboratory of Molecular Genetics and now at the Georgia Institute of Technology; first-year biology graduate students Eric Vitriol of UNC and Jennifer Stemple of the University of Southern California; and Dr. Michael A. Resnick of NIEHS. Both Vitriol and Stemple were UNC undergraduates in the College of Arts and Sciences when they worked on the study.
