London, Nov 25 : Scientists have attributed the ability of a green sea slug to run on solar power to plant genes that it stole from the algae it eats.
The slug, known as elysia chlorotica, has a gelatinous leaf-shaped body, that lives along the Atlantic seaboard of the US.
What sets it apart from most other sea slugs is its ability to run on solar power.
According to a report in New Scientist, Mary Rumpho of the University of Maine, an expert on E. chlorotica, has now discovered thatthe sea slug gets this ability by photosynthesizing with genes "stolen" from the algae it eats.
Rumpho known for some time that E. chlorotica acquires chloroplasts - the green cellular objects that allow plant cells to convert sunlight into energy - from the algae it eats, and stores them in the cells that line its gut.
Young E. chlorotica, fed with algae for two weeks, could survive for the rest of their year-long lives without eating, Rumpho found in an earlier work.
Chloroplasts only contain enough DNA to encode about 10 percent of the proteins needed to keep themselves running. The other necessary genes are found in the algae's nuclear DNA.
"So the question has always been, how do they continue to function in an animal cell missing all of these proteins," said Rumpho.
In their latest experiments, Rumpho and colleagues sequenced the chloroplast genes of Vaucheria litorea, the alga that is the sea slug's favorite snack.
They confirmed that if the sea slug used the algal chloroplasts alone, it would not have all the genes needed to photosynthesize.
They then turned their attention to the sea slug's own DNA and found one of the vital algal genes was present.
Its sequence was identical to the algal version, indicating that the slug had probably stolen the gene from its food.
The researchers believe many more photosynthesis genes are acquired by E. chlorotica from their food, but still need to understand how the plant genes are activated inside sea-slug cells.
According to Greg Hurst of Liverpool University in the UK, DNA jumping from one species to another is not unheard of, but normally, the DNA does not appear to function in the new species.
"Here we have something going across and working in an entirely different context, which is altogether more interesting," he told New Scientist.