Topo Cloning Procedure Topo Cloning procedure for cloning of small amounts DNA fragments by PCR. Cloning the PCR fragment into the TOPO vector, transforming E. Coli cells, and using blue/white selection to determine transformants. Culture inoculation, Qiagen Plasmid Prep protocol for plasmid isolation of the plasmid containing the cloned copies. Preuss Lab, Univ. Chicago.