MOBILE DNA that can jump between plant and bacterial species once hopped between diverse mammalian species. These transposons, or 鈥渏umping genes鈥�, might even have caused mass mammal extinctions about 30 million years ago.
Transposons are common in mammals, humans included, but are mostly thought of as parasitic DNA. Though they can relocate within an individual鈥檚 genome they were not thought able to switch species. However, Cedric Feschotte at the University of Texas, Arlington, and his team say that millions of years ago, transposons called SPIN, dubbed 鈥渟pace invaders鈥�, jumped into several mammal species by piggybacking on a virus. By assimilating itself into its new hosts鈥� sex chromosomes, SPIN got passed to future generations.
The team found near-identical lengths of SPIN in seven of the 26 animal genomes that have been sequenced (Proceedings of the National Academy of Sciences, ).
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These include species as varied as a bushbaby, a South American opossum, an African clawed frog and a tenrec, a hedgehog-like relative of elephants. SPIN鈥榮 ability to jump into such diverse species is startling, say the team. 鈥淚t鈥檚 like a pandemic that can infect species that weren鈥檛 genetically or geographically close. It鈥檚 puzzling; scary almost,鈥� Feschotte says.
The transposon bombarded the animals鈥� genomes with so much DNA, he says, it may have played a part in ancient mammal extinctions usually attributed to climate change.
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