Feb 16

Reported by Duncan Geere, Wired UK, February 14, 2011.

Researchers have discovered the first case of a direct transfer of a human DNA fragment to a bacterial genome. The guilty party? Gonorrhea.

A photomicrograph of a T3 colony of N. gonorrhoeae bacteria magnified at 100X. (Dr. Stephen J. Kraus/CDC)

Scientists have known that genes could transfer between different bacteria, and even between bacteria and yeast cells, but biologists at Northwestern University’s Feinberg School of Medicine discovered that Neisseria gonorrhoeae, the bacteria responsible for gonorrhea, had stolen a sequence of DNA bases (adenine, cytosine, guanine and thymine) from an L1 DNA element found in humans.

Hank Seifert, a senior author of the paper describing the research, due to be published in mBio, said in a press release: “This has evolutionary significance because it shows you can take broad evolutionary steps when you’re able to acquire these pieces of DNA. The bacterium is getting a genetic sequence from the very host it’s infecting. That could have far reaching implications as far as how the bacteria can adapt to the host.”

Seifert also screened the bacteria that causes meningitis, Neisseria meningitidis, which is very similar to the gonorrhea bacteria at the genetic level. There was no sign of the human DNA signature, suggesting that the gene transfer occurred relatively recently.

What isn’t known yet is what the sequence actually does, and therefore whether the theft will convey any evolutionary advantage to the bacteria. That’s what Seifert reckons he’ll focus on next, adding in the release: “Human DNA to a bacterium is a very large jump. This bacterium had to overcome several obstacles in order to acquire this DNA sequence. The next step is to figure out what this piece of DNA is doing.”

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