Circular RNA from predatory bacterium caught moving between microbes
Researchers have observed circular intron RNA from a tiny predatory bacterium inside the dead cells of another microorganism, providing direct evidence that mobile genetic elements, or 'jumping genes,' can transfer between species without relying on viruses or plasmids. The discovery challenges previous assumptions about the primary vehicles for such genetic movement.
The discovery centers on a specific self-splicing intron identified in the genome of *Ca. Velamenicoccus archaeovorus*. Using highly sensitive nucleic acid probes, the Max Planck team visualized this intron RNA both within the living predator and inside the deceased cells of its prey, *Methanothrix soehngenii*. This direct observation provides evidence of a mobile genetic element attempting replication in a foreign, though non-viable, host.
The survival of this RNA in dead cells is attributed to its circular structure. Unlike linear RNA molecules, which are rapidly degraded from their exposed ends, the ring shape resists enzymatic breakdown. This stability suggests a novel, non-viral, non-plasmid pathway for genetic transfer, although the specific event observed ended in a dead cell.
This finding could reshape how scientists understand the horizontal transfer of genetic material across microbial species. If circular intron RNA proves to be a viable vehicle, it may accelerate evolutionary adaptation in bacterial communities, potentially influencing how pathogens acquire new traits or how environmental microbes develop metabolic capabilities. Researchers may need to reconsider the primary mechanisms behind genetic mobility, though the practical implications for human health or agriculture remain speculative until further studies confirm transfer into living cells.