A pulse of electricity from an electric eel can make other fish take up DNA from the water in a tank. If this process occurs in nature, it could help organisms acquire new traits and evolve in unexpected ways.
In laboratories, scientists use electricity to create temporary pores in a cell membrane – a process called electroporation – which allows genetic material to be transferred into cells. at Nagoya University in Japan wondered whether this might also happen in nature.
In the wild, electric eels emit weak electrical pulses for sensing and stronger pulses to stun their prey or to defend themselves.
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Iida and his colleagues placed electric eels and zebrafish larvae in a tank of water containing DNA that codes for a green fluorescent protein. They fed an anaesthetised goldfish to an eel, which prompted it to emit pulses with an amplitude of around 185 volts.
After one day, some of the zebrafish larvae began to glow, showing that they had taken up the fluorescent protein gene.
When team member Shintaro Sakaki told Iida the result, he didn’t believe it at first. “So, we observed it together. Then, I was very excited,” he says. The fluorescence lasted for between three days and one week.
The findings suggest electric eels and other organisms that generate electricity could stimulate a kind of genetic modification in nature, says Iida, but further research is needed to confirm this.
at the University of Ljubljana in Slovenia says the result isn’t surprising, as any type of electricity can make microscopic holes in cell membranes that molecules can pass through. “Let’s say you drop a hairdryer into the bathtub – you will get this because electroporation is physics,” he says. His own work has suggested electroporation can be triggered by lightning.
One important question is whether the zebrafish could pass the genes on to the next generation, says Kotnik. He thinks this is unlikely because of how quickly DNA degrades.
But even if only one zebrafish in a million passes the DNA on to their offspring, it would be highly significant, he says, because “such discharges by electric eels could eventually generate new species or increase diversity”.
Iida is planning follow-up studies looking at whether electric eel discharges can make smaller organisms, such as bacteria and plankton, take up DNA.
Bacteria commonly exchange DNA through a process called horizontal gene transfer, says Kotnik. “Electric eels floating around a diverse set of bacteria could speed up the process of them cross-acquiring various traits, including [antibiotic] resistance.”
PeerJ
