| abstract |
The invention provides methods useful for establishing timing or spatial location of a biosynthetic event in a living organism, without disrupting the event of interest and without disrupting the living organism. A temporal or spatial gradient of an isotopically labeled biochemical precursor is created, which serves to isotopically fingerprint (i.e., definitively mark) when or where biosynthesis occurs. The methods of the invention are broadly applicable to a variety of medical, public health, and diagnostic applications, as well as for establishing sequences of biochemical events that occur within a living organism. |