High concentrations of sodium chloride induce a “positive” response at the tk locus of l5178y/tk± mouse lymphoma cells
✍ Scribed by Moore, Martha M. ;Brock, Karen H.
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1988
- Weight
- 187 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0192-2521
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✦ Synopsis
One of the mammalian cell gene-mutation assays that has been used extensively for mutagenicity studies is the L5178Y/TK+'--3.7.2C mouse lymphoma assay Oberly et al., 19841. This assay measures forward mutation at the functionally heterozygous thymidine kinase (rk) locus based on resistance to trifluorothymidine (TFT). We have been investigating factors that may impact test design and also influence the interpretation of test results. Factors that effect the magnitude of the quantitated mutant frequency include expression time [Moore and Clive, 19821 and both the growth medium [Moore and Howard, 19821 and the agar used in the cloning medium [Meyer et al., 19861. Other laboratories have identified test conditions (low pH, high salt) that will give "false positive" results in mammalian-cell assays [Brusick, 1986, 19871. In the present study we investigated sodium chloride for its ability to induce mutation at the tk locus of L5178YITK"--3.7.2C mouse lymphoma cells. This study confirms and expands the information from Myhr and coworkers [Brusick, 19861 that sodium chloride and other salts can give positive results in the mouse lymphoma assay.
Cells were maintained in culture according to the procedures of Turner et al. [1984]. L5178Y/TK+'--3.7.2C cells were treated with sodium chloride for 4 hr in the absence of exogenous metabolic activation according to procedures described