A turquoise glow inside a dead cell has rewritten the rules of genetic transfer. Under the microscope at the Max Planck Institute for Marine Microbiology in Bremen, scientist Jens Harder spotted something never seen before: RNA from a predatory bacterium, Candidatus Velamenicoccus archaeovorus, lingering inside the lifeless filaments of Methanothrix soehngenii, Earth’s most prolific methane-producing microbe. The glowing signal wasn’t just debris—it was a mobile intron, a type of jumping gene, caught mid-leap between species, offering the first direct evidence that genes can jump not just within genomes, but across the boundaries of life.
This discovery cracks open a long-standing mystery in evolutionary biology. While phylogenetic studies had hinted that genes occasionally hop between species—especially among microbes—scientists assumed such transfers happened via viruses or plasmids acting as genetic ferries. Harder’s team has now shown a different path: RNA itself, in the form of a circular intron, can survive outside its host and infiltrate another cell. In this case, the predator’s gene made it into its prey—but too late. The Methanothrix cell was already dead, the intron frozen in a final, failed attempt to replicate. Still, the evidence was undeniable: the gene had moved.
The key to this breakthrough was detecting RNA where it shouldn’t last. Normally, RNA degrades rapidly after a cell dies. But this intron forms a closed loop—a circular RNA with no loose ends for enzymes to chew up. That stability allowed it to persist long enough to be spotted using specially designed nucleic acid probes. "The stability of intron RNA in its ring form is a distinctive feature," Harder explains. "Our study has shown that in microorganisms, jumping genes can be transferred to other species via their circular RNA."
The implications ripple far beyond this anaerobic community, originally discovered in a limonene-degrading culture that smelled faintly of oranges. If circular RNA can carry genetic information between species, it could be a previously overlooked engine of microbial evolution—one that might operate in oceans, soils, and even the human gut. Moreover, the same structural resilience that lets these introns survive could inform advances in RNA technology, from vaccines to cancer therapies, where stable RNA molecules are highly prized.
This single observation, published in Scientific Reports by Harder and Jana Kizina, doesn’t just confirm a theoretical possibility—it reveals a new chapter in how life shares its code. The gene didn’t need a virus. It didn’t need a plasmid. It traveled on its own, a tiny, circular molecule slipping across the border of a dying cell, leaving behind a turquoise clue that evolution has more tricks up its sleeve than we ever knew.