Effects of Tris(1,3-dichloro-2-propyl) Phosphate on Growth, Reproduction, and Gene Transcription of <i>Daphnia magna</i> at Environmentally Relevant Concentrations

The synthetic flame retardant tris­(1,3-dichloro-2-propyl) phosphate (TDCIPP) has been frequently detected in natural waters, and its maximum concentration ever reported is 377 ng/L. However, information on the adverse effects of environmentally relevant concentrations of TDCIPP on aquatic organisms are totally unknown. In this study, <12-h old water fleas, <i>D. magna</i>, were exposed to concentrations of 0, 65 ± 7.1, 550 ± 33, or 6500 ± 1400 ng/L TDCIPP, and dose- and time-dependent effects on reproduction and development were evaluated. Sequences of genes of <i>D. magna</i> were obtained from the National Center for Biotechnology Information and were used to develop PCR arrays for <i>D. magna.</i> Arrays were then used to study transcriptional responses of <i>D. magna</i> to TDCIPP. Exposure to environmentally relevant concentrations of TDCIPP significantly decreased fecundity as well as length of F₀ and F₁ generations. Transcriptional responses showed that, of the 155 genes tested, expressions of 57 genes were significantly changed, and some changes occurred following exposure to environmentally relevant concentrations (i.e., 65 ± 7.1 and 550 ± 23 ng/L). Furthermore, pathways related to protein synthesis and metabolism and endocytosis were considered to be significantly affected in a dose- and time-dependent manner and might be responsible for TDCIPP-induced reproductive and developmental toxicities