Tuesday, December 7, 2010
Using Arsenic to Build Cells
This article http://www.wired.com/wiredscience/2010/12/nasa-finds-arsenic-life-form/, talks about a group of scientists that coaxed a bacterium to use arsenic in place of phosphorus as an elemental building block. There is some debate regarding the findings, but if the bacteria really are using arsenic as a building block, then this would be a scientific first. Arsenic is right below phosphorus on the periodic table of elements, which means that the two elements share some characteristics, although arsenic would normally destroy any cell it came into contact with. To be honest, I wasn't too surprised at the finding. It fits with my concept of an alternative world in which the infinite possible permutations of life are allowed to exist due to a hypothetical absence of influence. The bacteria normally exist in an extreme environment in which certain mutations were strongly selected for, then the scientists altered their environment further, allowing other changes to occur that might not have normally taken place. It raises the question of what other weird things life could do in an artificial environment in which the normal rules of biology are tweaked.
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So arsenic is poisonous to multicellular bacteria, but were these bacteria unicellular? Do you think humans could eventually evolve to tolerate arsenic in our water? If we haven't already... I wonder how many things we've adapted to...
ReplyDeleteI think the point is that the adaptations that resulted in the life forms that we know are a product of their environment. So if CHNOPS is abundant in your environment of evolutionary adaptedness, it is likely to be used as a basic element in constructing cells. If an organism's environment consists of large amounts of arsenic, then it's likely that, over huge expanses of time, mutations will result that somehow incorporate the element, even though it is normally toxic. Think of antibiotics. They will normally kill bacteria, but there are always a few individuals with mutations that make them impervious to the antibiotic. It's a different process that occurs with the arsenic, but the idea is the same and central to the theory of natural selection: alter an organism's environment and mutations that were once rare will now thrive in the new environment, changing the composition of the population to consist mainly of the new mutation. We are used to seeing life that evolved in one general environment, but things always change.
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