AN ASSAY SYSTEM FOR DETECTING ENVIRONMENTAL TOXICANTS WITH CULTURED CLADOCERAN EGGS IN-VITRO - MALFORMATIONS INDUCED BY ETHYLENETHIOUREA

An in vitro assay system using cladoceran eggs was developed for the d etection of toxic compounds in the aquatic environment. Parthenogeneti c eggs of Daphnia magna were removed from the brood chambers of female adults and cultured individually in 96-well microtiter plates with El endt M7 medium at 23 degrees C. Embryonic development proceeded comple tely in vitro with more than 95% hatchability. Egg development time in vitro was 2 days, which was almost equal to that in the brood chamber of the mother. Ethylenethiourea, a compound teratogenic to mammals, w as investigated for toxicity to development of eggs. Isolated eggs wer e cultured in the presence of ethylenethiourea during the period of em bryonic development for 3 days. Treatment with ethylenethiourea induce d morphological abnormalities in the cladoceran carapace. Parthenogene tic eggs of Cladocera are genotypically identical, which makes them us eful biological materials for a toxicity test on aquatic pollutants. ( C) 1998 Academic Press.