A recent study has found that the electricity produced by an electric eel’s discharge is strong enough to cause the transfer of genetic material from the environment into the cells of nearby animals. The finding suggests that electric eels – and other electricity-generating organisms – could affect genetic modification in nature.
In the lab setting, electroporation involves the application of an electric field to cells to increase the permeability of their cell membrane, which allows foreign DNA to be introduced. It’s the technique that’s used to produce the knockout mice that are used in research experiments, as well as in tumor treatment and gene- and cell-based therapies.
Now, a new study by researchers from Nagoya University in Japan suggests that the electric eel is capable of electroporation in its natural environment.
“I thought electroporation might happen in nature,” said Atsuo Iida, corresponding author of the study. “I realized that electric eels in the Amazon River could well act as a power source, organisms living in the surrounding area could act as recipient cells, and environmental DNA fragments released into the water would become foreign genes, causing genetic recombination in the surrounding organisms because of electric discharge.”
Electric eels are a power source, alright. The biggest volt-making creature on Earth, they can release up to 860 V with one of their electric organ discharges (EOD). The researchers placed an eel in a freshwater tank with six-day-old zebrafish larvae. DNA carrying green fluorescent protein (GFP) was added to the tank water.
When an anesthetized goldfish was lowered into the tank as prey, the eel emitted an EOD and consumed the goldfish. After EOD exposure, the researchers examined the zebrafish larvae under a stereomicroscope, focusing on clusters of multiple cells displaying intense green fluorescence under UV light. In total, 5.3% of the larvae exhibited GFP-positive cells.
“This indicates that the discharge from the electric eel promoted gene transfer to the cells, even though eels have different shapes of pulses and unstable voltage compared to machines usually used in electroporation,” Iida said. “Electric eels and other organisms that generate electricity could affect genetic modification in nature.”
The researchers note that their study only provides evidence of environmental gene transduction and doesn’t confirm whether the transferred gene functions as a heritable factor in offspring. Though they tried to validate heritable transgenesis using single-celled organisms, including E. coli, they didn’t yield positive results, probably because the voltage generated by the eel was around 200 to 250 V, which might have been insufficient for electroporation. For E. coli, machine-based electroporation typically uses discharges exceeding 1 kV. Further studies are needed to explore the heredity of electric discharge-mediated transgenesis in natural habitats.
The researchers were understandably excited by their findings.
“I believe that attempts to discover new biological phenomena based on such ‘unexpected’ and ‘outside-the-box’ ideas will enlighten the world about the complexities of living organisms and trigger breakthroughs in the future,” Iida said.
The study was published in the journal PeerJ: Life and Environment.
Source: Nagoya University
