Bacterium uses arsenic in DNA

[asterroc]

NASA's big press release today was that a new form of DNA was discovered in a type of bacteria living in Mono Lake, California. DNA usually requires phosphorus to hold together the different "rungs" of the "ladder". On the periodic table of the elements, phosphorus falls directly above arsenic, meaning they have the same number of electrons in their outer shells, and therefore act similarly in forming molecules. This is the very reason that arsenic is well-known as a poison: it is easily incorporated into human (or animal, or plant) chemistry, it replaces the phosphorus, but it does a crappier job than phosphorus and even though it can form similar molecules they easily fall apart.

Apparently this bacterium has not only overcome that - there are many bacteria that can live in an arsenic-rich environment - but it even uses that fact. This bacterium can apparently switch between using phosphorus, and using arsenic, depending upon which is available in its environment.

NASA press release

A very slightly more technical article, including a description of tests used to determine that the arsenic is actually incorporated into the DNA.

And a couple blog posts, one from a science writer Ed Yong, one from astronomer-turned-science-writer Phil Plait.

Comments

[zandperl.livejournal.com]

We study the one example in depth and extrapolate out to learn more about other examples. This is always the case in science.

We breed fruit flies and study their DNA because they have quick reproduction cycles, and then use this to draw conclusions about human genetics. We infect mice with cancer and try different treatments on them so that we can learn how to treat cancer in humans. We use earthquakes here on Earth to determine the size of Earth's core, and relate that to the interior compositions of the Moon, Mars, and even Jupiter. We study the language of indigenous people in Siberia and from that we can better understand how languages relate to each other. We teach a parrot a few words and that tells us why humans even have language in the first place. We look at how birds are related throughout the islands of the Galapagos and this helps us understand how all species are related to each other. We watch an apple fall on the Earth and this spawns the study of gravity in the universe.

The process of extrapolation is crucial to all fields of science. It is 100% necessary for us to study the small things close to home that we can easily put our hands on in order for us to understand the big picture. As an added bonus, these seemingly insignificant things tend to cost less money than the huge intractable projects, and yet will lead to great things down the road.