I am currently performing a plasmid construction based on T4 DNA ligase. I first designed primers to incorporate identical restriction sites at both the 3' and 5' ends of the target fragment. This was followed by PCR amplification, single-enzyme digestion (using the corresponding restriction enzyme), and gel extraction/purification. Finally, the fragments were ligated under standard conditions using T4 DNA ligase. The ligation product was then analyzed by agarose gel electrophoresis. I observed bands with different electrophoretic mobility compared to the linear fragment. Do these bands indicate successful in vitro ligation? I am constructing a pUC19-oriC plasmid and, therefore, did not transform competent cells, hoping to achieve complete plasmid assembly in vitro.