I usually tend to downplay worries about research in genetics, but I was quite concerned after reading this article. The researchers surely have plans to keep whatever they create contained. But adding a fifth base to the DNA of bacteria with a genetic mutation rate 10,000 times that of normal bacteria seems unnecessarily dangerous. I guess my concerns were primed by “Quick Fix: How invasive seaweed repairs its wounds” (SN: 4/2/05, p. 214), which discusses an “alien green alga that’s currently wreaking havoc in the Mediterranean Sea.”

Andy Olesin
Princeton, Mass.

The concerns connect in your articles about man-made seaweed and scientists creating a fifth base for DNA in bacteria. These human-modified species get loose, and bad things happen.

Gil Stevens
Fairview, Texas

It’s unlikely that a bacterium would survive with such a high mutation rate. What’s more, should such modified organisms make their way into the environment, they would need a constant supply of 3-fluorobenzene, and there’s none of that chemical in the environment. Furthermore, the seaweed wasn’t genetically modified. —A. Goho