Dibbie dibbie pop da pop pop ya don’t stop
Last year, a team of NASA-funded scientists claimed to have found bacteria that could use arsenic to build their DNA, making them unlike any form of life known on Earth. That didn’t go over so well. One unfortunate side-effect of the hullabaloo over arsenic life was that people were distracted from all the other research that’s going on these days into weird biochemistry. Derek Lowe, a pharmaceutical chemist who writes the excellent blog In the Pipeline, draws our attention today to one such experiment, in which E. coli is evolving into a chlorine-based form of life.
Scientists have been contorting E. coli in all sorts of ways for years now to figure out what the limits of life are. Some researchers have rewritten its genetic code, for example, so that its DNA can encode proteins that include amino acids that are not used by any known organism.
Others have been tinkering with the DNA itself. In all living things, DNA is naturally composed of four compounds, adenine, cytosine, guanine, and thymine. Thymine is a ring of carbon and nitrogen atoms, with oxygen and hydrogens atoms dangling off the sides. Since the 1970s, some scientists have tried to swap thymine for other molecules. This compound is called 5-chlorouracil, the “chloro-” referring to the chlorine marked here in red. No natural DNA contains chlorine.
related { The end of E. Coli }
