I'm getting no colonies after transformation. What should I do?
No colonies may occur due to the following problems:
Bacteria were not competent. Use the pUC18 vector included with the One Shot module to check the transformation efficiency of the cells.
- Incorrect concentration of antibiotic on plates, or the plates are too old. Use 100 µg/mL of ampicillin or 50 µg/mL kanamycin. Be sure ampicillin plates are fresh (< 1 month old).
- The product was phosphorylated (TOPO cloning only). Phosphorylated products can be TA-cloned but not TOPO-cloned. This is because the necessary phosphate group is contained within the topoisomerase-DNA intermediate complex of the vector. The TOPO vector has a 3' phosphate to which topoisomerase is covalently bound and a 5' phosphate. The non- TOPO vectors (TA and Blunt) have a 3' OH and a 5' phosphate. Phosphorylated products should be phosphatased (CIP) before TOPO-cloning.
Bacteria were not competent. Use the pUC18 vector included with the One Shot module to check the transformation efficiency of the cells.
- Incorrect concentration of antibiotic on plates, or the plates are too old. Use 100 µg/mL of ampicillin or 50 µg/mL kanamycin. Be sure ampicillin plates are fresh (< 1 month old).
- The product was phosphorylated (TOPO cloning only). Phosphorylated products can be TA-cloned but not TOPO-cloned. This is because the necessary phosphate group is contained within the topoisomerase-DNA intermediate complex of the vector. The TOPO vector has a 3' phosphate to which topoisomerase is covalently bound and a 5' phosphate. The non- TOPO vectors (TA and Blunt) have a 3' OH and a 5' phosphate. Phosphorylated products should be phosphatased (CIP) before TOPO-cloning.