Transcriptome alterations in female Daphnia (Daphnia magna) exposed to 17β-estradiol.

The molecular mechanism of evaluating 17β-estradiol (E)-induced toxicity in female Daphnia magna has not been determined. In this study, the transcriptome of D. magna was analyzed after exposure to three different concentrations (0, 10, and 100 ng L) of E at 3, 6, and 12 h. The results showed 351-17,221 significantly up-regulated and 505-10,282 significantly down-regulated genes (P < 0.05). Overall, the selected largest 10,282 (10 ng Lvs control at 12 h) down-regulated and 17,221 (100 vs 10 ng L) up-regulated genes were identified; following annotation, pathways in cancer and RNA transport were found to be enriched according to the interaction network. Among all completed comparisons, KEGG pathways related to the immune system, cancer, disease infection, and active compound metabolism were identified by short time series expression miner analysis. A different set of genes fluctuated in a "U"-shaped pattern over time and at different concentrations of E, whereas some genes associated with disintoxication showed a reverse "U"-shaped response as E administration was increased. These results suggest that E exposure caused transcriptional changes in the immune system, disintoxication, disease prevention, and the protein degradation pathway.