Ancient DNA Repairs Itself

Markus Dieser

Brent Cristner

Science uses DNA as a means of identifying, learning about, and dealing with organisms. This makes DNA very important, and therefore crucial in the understanding of evolutionary development over long periods of time. But how does DNA actually stay intact for such long periods? The answer is simple: DNA repair mechanisms. Before I get in to what that means, let me talk about how this answer came to be realized. An LSU professor by the name of Brent Christner, along with his postdoctoral research associate Markus Dieser had already been working with bacteria within ice. They knew that DNA gradually decays, but that somehow they could take virtually perfect DNA from a sample of ~750,000 year old bacteria that was trapped in low layers of ice. Could the DNA be repairing itself, even within such molecule-slowing conditions? By exposing samples of specimens in Siberian permafrost to ionizing radiation (the dosage of which was felt ~250,000 years ago, about the time this permafrost layer was formed) to break up the DNA into small, unidentifiable pieces. These fragments were stored for two years in incubation. Over these two years, the DNA gradually put itself together. My question to you is this: How could this information be helpful to science in the long run?

For more information, here is a link to the research: http://aem.asm.org/content/early/2013/09/23/AEM.02845-13