My collaborators have taken pity on me and sent me some of their control analysis data. This is mass-spectrometry analysis of a control DNA sample I sent several months ago.
The GFAJ-1 cells this DNA was purified from were grown in medium without arsenic, so we don't expect to find any arsenic in the DNA. This DNA was just used to test the methods they will use, but it also provides some measure of the purity of the DNA I sent them. That's because this DNA hasn't been put through the CsCl-density-gradient purifications step that they'll use for the new DNA samples I sent a few weeks ago.
I'm going to have to put in a bit of work before I have any idea of what I'm looking at. But I'm not complaining - this is exactly the part of science I like best.
6 hours ago in Variety of Life