Inducible expression of TcSOD A. Two clones containing pTcINDEX-SOD A9E10 on a CL-Brener [pLEW13] background were induced with 0.25 μg ml-1 tetracycline for five days. Replicate cultures were grown in the absence of tetracycline. Protein extracts were made and analysed by SDS-PAGE, western blotting and enzyme assay. A) Western blot of a gel stained with the mouse monoclonal 9E10. A single band of approximately 25 kDa was recognised by the antibody. B) Coomassie stained SDS-PAGE gel showing lysates from control and induced populations of clones A1 and A2. Note the intense band appearing in the induced lanes, at the position of the band recognised by the antibody in A. C) Relative SOD activities of the trypanosome lysates as measured using the SOD 525 assay system. Each assay was performed in triplicate. Clone A1 showed a 14:1 ratio of SOD activity between induced and uninduced cells, while clone A2 showed an 18:1 ratio.