sentence: The amplification was conducted in a Robocycler Thermal Cycler ( Stratagene , La Jolla , CA ) in a 50-ml reaction volume containing 1 µ l of the first-strand cDNA as template , 1 unit of Taq DNA polymerase ( Invitrogen ) , 0.5 µ M concentration of each primer , 0.2 mM dNTP , and 1 × PCR buffer ( 2 mM MgCl , 50 mM KCl , 20 mM TrisYHCl , pH 8.4 ) .