I totally agree with Mike M. above. I'm a microbiologist and the evidence for the arsenic-based life is VERY shaky. I'd pull that from your list of four for the time being. Once other labs get GFAJ-1 and start testing it independently, then maybe we can have a more informed discussion about it. Right now, the only published report about arsenic-based life is by people who weren't really that diligent in their experiments.