In my never ending quest to keep you, my beloved reader, informed on the latest intestinal developments, I link you to another article in Science Blog about intestinal biochemistry. Intrepid researchers right here in River City have discovered just what the heck the molecule MR1 does. Apparently, mucosal-associated invariant t cells (MAIT cells for short and the squeamish) somehow rely on intestinal bacteria and MR1 to keep your gut infection free, a thankless but vital job. The research team has also set its sights higher, to the lungs, to see if MR1 is on the job there, too.