| Popis: |
S49 are mouse thymic lymphoma cells which do not express the two closely linked mouse metallothionein (MT) genes; however, previous studies demonstrated that treatment of S49 cells with chemical carcinogens or ultraviolet irradiation can activate these quiescent genes. To determine if activation of MT-I or MT-II in these variants is a result of cis-acting mutations, we amplified and sequenced the immediate 5' regions of 19 cadmium resistant S49 variants: MT-I+/MT-II-, MT-I-/MT-II+, MT-I+/MT-II+, and MT-I-/MT-II-. None of the variants contained mutations in the analyzed regions. Thus, the observed changes in MT expression must result from mutations at other sites or from non-mutational mechanisms. |
