Sunday, December 05, 2010

Arsenic-associated bacteria (NASA's claims)

Rosie Redfield blogged about NASA's claims, Arsenic-associated bacteria and tore them to shreds.

"Bottom line:  Lots of flim-flam, but very little reliable information.  The mass spec measurements may be very well done (I lack expertise here), but their value is severely compromised by the poor quality of the inputs.  If this data was presented by a PhD student at their committee meeting, I'd send them back to the bench to do more cleanup and controls.

There's a difference between controls done to genuinely test your hypothesis and those done when you just want to show that your hypothesis is true.  The authors have done some of the latter, but not the former.  They should have mixed pregrown E. coli or other cells with the arsenate supplemented medium and then done the same purifications.  They should have thoroughly washed their DNA preps (a column cleanup is ridiculously easy), and maybe incubated it with phosphate buffer to displace any associated arsenate before doing the elemental analysis.  They should have mixed E. coli DNA with arsenate and then gel-purified it.  They should have tested whether their arsenic-containing DNA could be used as a template by normal DNA polymerases.  They should have noticed all the discrepancies in their data and done experiments to find the causes."

Anyone with more knowledge on the subject than me want to read through it and see if it makes sense?

1 comment:

Paul said...