| 摘要 |
Genotoxicity testing can be carried out using a genetic hybrid cell line, for example, a CHO cell line which contains human chromosome 11. This exemplified hybrid cell line expresses human CD59 on the cell surface, and the human CD59 gene serves as a test for mutagenic agents. The hybrid cell line is grown in the presence of a test compound, and the loss of cell surface CD59 is followed using a fluorescent-labeled antibody specific for human CD59 and flow cytometry to monitor the presence or absence of labeled antibody on particular cells. Absence of the labeled antibody on the surface of the cells is indicative of a mutation in the CD59 gene such that either no CD59 protein is made or there has been a mutation which results in the loss of the antibody binding site. A test compound which causes CD59 loss is deemed to be genotoxic (i.e., mutagenic). The mutations can be point mutations, deletions, inversions, insertions, or frameshifts. The sensitivity of the assay is improved when the cells are first panned with antibody specific for the cell surface marker to remove spontaneous mutants prior to challenge with the test compound. Alternatively, or in addition, an antibiotic resistance marker is incorporated onto the same chromosome as the cell surface marker, and an antibiotic selection step precedes the challenge with the potential genotoxic composition or condition.
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