Effects of cadmium on Drosophila: toxicity, proteins, and transfer RNAs

An animal model with well-defined genetic and biochemical characteristics is needed for a detailed understanding of the mechanism of toxicity by metal ions. Drosophila melanogaster was used in the present study to demonstrate a number of responses of Cd²⁺, including lethality, age-related changes in resistance, alterations of the normal developmental changes in proteins, and alterations in specific transfer RNAs. Genotype-specific differences in resistance to Cd²⁺ were found: the ν; bw strain was 5–10 times more resistant than su(s)²ν; bw for developmental exposure; upon treatment of the young adults the differences were in the same direction, but the sensitivities differed by only two- to three-fold. The adult fly became more sensitive to Cd²⁺ as it aged through 2 weeks, but changed little thereafter. The electrophoretic patterns of proteins of adult flies underwent changes during aging from 1 to 8 days; these changes were markedly altered by 0.55 mm CdCl₂ but not by 0.74 mm ZnCl₂ in the medium on which the flies were maintained. The appearance of queuosine-containing tRNA was stimulated by CdCl₂ (0.05–0.8 mm) in the growth medium, but not by ZnCl₂ (0.07–1.1 mm). Further studies involving D. melanogaster should be useful in defining specific interactions of toxic metal ions with macromolecules to enhance the understanding of the toxic effects of these and similar pollutants.