Effects of cadmium on gene expression in cadmium-tolerant and cadmium-sensitive Datura innoxia cells
1989
Delhaize, E. | Robinson, N.J. | Jackson, P.J.
The effect of Cd on gene expression in suspension cultures of two Datura innoxia cell lines with differing, Cd tolerance was studied. In vivo labeling experiments using [3H]leucine showed that Cd induced the synthesis of a similar range of proteins in both cell lines at a concentration which will kill the sensitive but not the tolerant cells. Corresponding changes in levels of translatable mRNA were also observed. The induction of the synthesis of proteins by Cd was transient since Cd-tolerant cells rowing continuously in 250 micromoles CdCl2 contained a similar set of in vitro translation products to cells growing in the absence of Cd. Although Cd had a similar effect on gene expression in both cell lines, Cd-tolerant cells possess two abundant mRNAs which are constitutively produced. These mRNAs encode proteins of low molecular weight (about 11 kDa) and are either absent or present at a low level in Cd-sensitive cells. The functions of these proteins are not known but they may be involved in the tolerance mechanism. Two-dimensional gel electrophoresis of in vitro translation products showed that many of the Cd-induced proteins are also induced by heat shock. A 42 degrees C heat shock resulted in a greater range and more intense induction of translatable mRNAs than 4 h exposure to 250 micromoles CdCl2. However a subset of mRNAs were induced specifically by Cd while other mRNAs were heat shock-specific. There was no difference in the ability, of the two cell lines to tolerate heat shock. This was also reflected by the same pattern of major proteins induced by heat shock in the two cell lines.
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