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Archive - May 7, 2012

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Orangutans Host Ancient Jumping Genes

Louisiana State University’s Dr. Mark Batzer, along with research associate Dr. Jerilyn Walker and assistant professor Dr. Miriam Konkel, have published research determining that modern-day orangutans are host to ancient jumping genes called Alu, which are more than 16 million years old. The study was done in collaboration with the Zoological Society of San Diego and the Institute of Systems Biology in Seattle and was published online on April 30, 2012 in the new open access journal Mobile DNA. These tiny pieces of mobile DNA are able to copy themselves using a method similar to that of retroviruses. They can be thought of as molecular fossils, as a shared Alu element sequence and location within the genome indicates a common ancestor. But, because this is an inexact process, a segment of “host” DNA is duplicated at the Alu insertion sites and these footprints, known as target site duplications, can be used to identify Alu insertions. “However, it has long been recognized that only a small fraction of these elements retain the ability to mobilize new copies as ‘drivers,’ while most are inactive,” said Dr. Batzer, Boyd Professor and Dr. Mary Lou Applewhite Distinguished Professor of Biological Sciences. “In humans, telling the difference has proven quite difficult, mainly because the human genome is filled with plenty of relatively young Alu insertions, all with slight differences while at the same time lacking easily identifiable features characteristic for Alu propagation. This makes it hard to find their ‘parent’ or ‘source Alu’ from potentially hundreds of candidates that look similar.” In contrast to humans and other studied primates, recent activity of Alu elements in the orangutan has been very slow, with only a handful of recent events by comparison.