ABOVE: Color photograph of the retina of a patient with atrophic macular degeneration
JAYAKRISHNA AMBATI
Over the past decade, there have been scattered reports of mammalian cells’ own DNA being found in the cytoplasm, mainly in the context of disease and aging. While it is not unusual to find DNA from an invading organism there, the presence of an organism’s own genetic code—in the form of complementary DNA (cDNA) synthesized from an RNA template—has puzzled scientists. In each case, the cDNA has come from endogenous retrotransposons, known for their copy-and-paste mechanism that results in the insertion of new copies of themselves into the genome. This process typically takes place in the nucleus, so the cytoplasmic cDNA lacked an explanation.
After detecting cDNA of Alu, the most abundant retrotransposon in the human genome, in the cytoplasm of cells modeling a degenerative eye disease, University of Virginia ophthalmologist Jayakrishna Ambati and his colleagues ...
