Role of the Left Side of the X Chromosome in Cadmium Resistance in Drosophila melanogaster

This paper concerns a line of D. melanogaster that we have selected for resistance to the lethal effects of cadmium exposure. This has important implications for human health since heavy metals such as cadmium are common contaminants in urban areas and may act as genotoxic agents. Our resistant line is descended from a wild-type line (Berlin) that has been selected on cadmium for over fifty generations, the last twenty-six of which were done continuously. The resistant line survives to adulthood in cadmium environments of 0.08 mg/mL about 70% as often as water controls, while the non-resistant wild-type line survives at about 1.5%. The mechanism of resistance in our line remains undetermined, but previous experiments suggest that this mechanism is X-linked and does not rely on metal ion sequestration. In order to locate the region on the X chromosome that confers cadmium resistance, we measured the survival of recombinant lines on Cadmium that were either homo- or hemizygous for segments of the X chromosome from the resistant line. Data suggests that the region between recombinant map locations 1-5 and 1-33 confers at least some of the resistance mechanism. 7 candidate genes, skpA, ovo, Grip, Gclc, Moe, mgl, and Hk have been identified as potentially involved in our line’s mechanism of resistance. Any combination of these genes may work in concert to enable the cadmium resistance in our line