Development and teratogenic effects of methyl mercury on Drosophila

Eggs from Drosophila melanogaster were transferred to food media containing 0.01, 0.10, 0.25, 0.50, 0.75 and 1.00 ppm methyl mercuric chloride (MMC). At 0.1 to 0.50 ppm MMC an increase in pupation rate occurred. At higher concentrations (0.75 to 1.00 ppm) a decreased pupation rate was seen. An increased developmental time was also noted for larvae exposed to more than 0.50 ppm MMC. At higher concentrations (0.10 ppm to 1.00 ppm), a marked decrease in the percentage of wild type flies occurred, indicating an increase in mutation rate at these dose levels. Mutant flies displayed 3 anomalies: loss of wild type body color; elongation of the abdomen, giving it a cylindrical appearance; and severely wrinkled and shortened wings. Both sexes were affected. Mutants appeared weakened and died within hours of emergence from pupal casings. A shift in the sex ratios of population exposed to various amounts of MMC also occurred. When all the hatched flies were considered, the sex ratio favored females. However, if only wild type flies were considered, the sex ratios favored males. These observations indicated that there was a difference in the toxicity of MMC towards the developing male and female Drosophila.