With RNA, Researchers Transfer Memories Between Sea Slugs [discovermagazine.com]
In the first chunk of their study, the team, led by David Glanzman, worked with groups of a marine slug called Aplysia. One group of slugs got shocked on the tail once every 20 minutes for a total of five shocks. The next day, they went through the same shock session. The point was to prime them to use what's called a defensive withdraw reflex — basically, the slug version of a flinch.
When Glanzman and his team later physically tapped these slugs on their tails, the creatures contracted for an average of 50 seconds. But when the team tapped another, shock-free group, those slugs only shied away for about one second.
Here's where things get interesting. The researchers then extracted ribonucleic acid (RNA) — the cellular messenger that carries out the genetic instructions of DNA — from the nervous systems of both the shock and non-shock groups. They took this RNA and injected it into a third set of slugs that hadn't had to deal with any shocks or taps. Seven of these slugs got the shock group's RNA, seven got the non-shock-group's RNA.
Next, the team tapped these RNA-injected slugs on their tails. Those that had received the shock group's RNA responded almost exactly like the shock group: They recoiled for about 40 seconds. "It was as though we transferred the memory," Glanzman said in a press release.
Also at Smithsonian Magazine [smithsonianmag.com].
RNA from Trained Aplysia Can Induce an Epigenetic Engram for Long-Term Sensitization in Untrained Aplysia [eneuro.org] (open, DOI: 10.1523/ENEURO.0038-18.2018) (DX [doi.org])