Counter-selectable markers

gene(selection condition)
 * 1) lacY (t-o-nitrophenyl-B-D-galactopyranoside)
 * 2) thyA (trimethoprim)
 * 3) pheS (p-chlorophenylalanine) see PMID 8125286
 * 4) *Relaxed substrate specificity mutant of phenylalanine tRNA transferase that will incorporate p-chlorophenylalanine into proteins, killing the cell
 * 5) ?(phage)
 * 6) *probably >1 gene can confer resistance?
 * 7) *previous work (Novick/Szilard) has mapped mutation rates confering T1 resistance in chemostats.
 * 8) pyrF (5FoA)
 * 9) *Jeff has ordered synthesized/BB'd
 * 10) *in pyrF- strains can be selected on medium w/o Uracil, so can be selected and coutner-selected.
 * 11) sacB
 * 12) tet? - see http://www.openwetware.org/wiki/Tetracycline
 * 13) UPRT
 * 14) others???