Hatching, toxicity endpoints

Early life-stages. Hatching and larvae development as endpoints of toxicity... 

In the past few years the use of rotifers in ecotoxicological studies has substantially increased. The main endpoints used are mortality, reproduction, behavior, cellular biomarkers, mesocosms, and species diversity in natural populations [126]. Several workers have used Brachionus calyciflorus for various types of toxicity assessments. Thus, comprehensive evaluation of approximately 400 environmental samples for the toxicity assessment of solid waste elutriates, monitoring wells, effluents, sediment pore water, and sewage sludge was carried out by Persoone and Janssen [127]. The mortality of rotifers hatched from cysts is evaluated after 24 hours exposure. This microbiotest has been commercialized in a Rotoxkit F [128,129]. 

The mouse preimplantation assay (MEPA) uses zygotes recovered from mated females, cultured in vitro for 7-10 days to assess embryo development, hatching, and survival that represent the toxicological endpoints [19]. The test is capable to assess toxic effects on preimplantation embryo development and survival in vitro up to hatching, a stage that precedes in vivo embryo implantation. It is a commercially available test, but still it has not been standardized and transferability to other laboratories must be addressed. 

Embryo hatching success and posthatch larval survival of the marine fish Sciaenops ocellatus were not affected by RDX at the highest concentration achieved without the use of a solvent carrier (299 pmoles L 1) [15] (Table 4.6). At its solubility limit, this chemical was also neither acutely toxic to marine crustaceans and polychaetes, nor exhibited sublethal effects in tests with echinoids [15], whereas adverse effects were observed with the macroalga U.fasciata zoospore germination, the polychaete D. gyrociliatus reproduction, and the 30-min Microtox bioluminescence endpoints [15,30] (Table 4.6). 

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