Scientists have confirmed for the first time that one extraordinary species of sea slug ‘steals’ genes from the algae it eats, which enables it to photosynthesize like a plant and gain energy from sunlight. This exceptionally weird phenomenon is one of the only examples of inter-species gene transfer, and it could lend us clues for future research into gene therapy techniques.
The study, published in The Biological Bulletin, details how researchers used advanced imaging techniques to “to confirm that a gene from the alga V. litorea is present on the Elysia chlorotica slug’s chromosome.” Not only is it present, but it is functional, and able to produce an enzyme that is critical to the function of chloroplasts—the components of plants and algae that capture sunlight and drive photosynthesis.
Once the sea slugs have ingested the algae, and the gene, the slug’s own chloroplasts function for up to nine months—a notably longer lifespan than the chloroplasts have in algae. The photosynthetic sea slug can then gain all the nutrition it needs from sunlight. Moreover, the sea slug passes this gene on to its offspring.
The report notes that each generation of sea slugs must “take up chloroplasts anew from algae, [but] the genes to maintain the chloroplasts are already present in the slug genome.” This in turn does funny things to our concept of evolution. Typically evolution occurs over thousands of years, but with inter-species gene transfer, evolution can happen from one generation to the next.
So what does this mean for the sea slugs? Report co-author Sidney K. Pierce an emeritus professor at University of South Florida and at University of Maryland, College Park explains: “There is no way on earth that genes from an alga should work inside an animal cell,” Pierce says. “And yet here, they do. They allow the animal to rely on sunshine for its nutrition. So if something happens to their food source, they have a way of not starving to death until they find more algae to eat. ”
For humans, it gives us a conceivably new way of looking at gene therapy for the treatment of genetic illness, but not without a caveat. Pierce says: “Is a sea slug a good [biological model] for a human therapy? Probably not. But figuring out the mechanism of this naturally occurring gene transfer could be extremely instructive for future medical applications.”
Lead image courtesy Patrick Krug, second image via Shutterstock