Mainstream science reporting is continuing its stellar job of reporting the facts absent context or clear baseline science literacy. I wish political reporting was handled the same way. I want to see more anchormen struggling to follow a train of thought instead of confidently making half-baked assertions. We can all pretend we’re political analysts, but it’s a lot harder to fake your way around a lab.
NASA has announced that arsenic-based life exists here on Earth. And no, it’s not alien. But, it expand the possibility of what evolving life may look like. Ed Yong notes “the results have nothing to do with aliens.” Thanks Ed, but we loves us some aliens. so that’s how it’s being sold. Arsenic E.T. is so cute. Why not buy a key-chain?
Fortunately, I know just enough about biology to find the following segment of Ed Yong’s piece understandable and interesting.
In 2008, Ronald Oremland (who was also involved in the latest study) discovered bacteria in Mono Lake that can fuel themselves on arsenic. Like plants, they can photosynthesise, creating their own food using the power of the sun. But where plants use water in this reaction, the bacteria used arsenic. Wolfe-Simon has taken these discoveries a step further, by showing that the bacteria are actually incorporating arsenic into their most important of molecules.
She took sediment from Mono Lake and added it to Petri dishes containing a soup of vitamins and other nutrients, but not a trace of phosphorus. She took samples from these dishes and added them to fresh ones, gradually diluting them to remove any phosphorus that might have stowed away onboard. And all the while, she added more and more arsenic.
Amazingly, bacteria still grew in the dishes. Wolfe-Simon isolated one of these arsenic-lovers – a strain called GFAJ-1. Using an extremely sensitive technique called ICP-MS that measures the concentrations of different elements, she showed that the cells of these bacteria did indeed contain large amounts of arsenic.
By giving the bacteria a mildly radioactive form of arsenic, Wolfe-Simon could also track where the element ended up in the cells. The answer: everywhere. There was arsenic in the bacteria’s proteins and in their fat molecules. It had replaced phosphorus in many important molecules including ATP. It was even in their DNA, a conclusion that Wolfe-Simon backed up with a number of other techniques. All other life uses phosphorus to create the backbone of the famous double helix, but GFAJ-1’s DNA had a spine of arsenic.
It’s an amazing result, but even here, there is room for doubt. As mentioned, Wolfe-Simon still found a smidgen of phosphorus in the bacteria by the end of the experiment. The levels were so low that the bacteria shouldn’t have been able to grow but it’s still not clear how important this phosphorus fraction is. Would the bacteria have genuinely been able to survive if there was no phosphorus at all? (Yong)
Oh, and here’s the official NASA report. Tenacious little buggers, no? And they’re darling.
