Abstract: OBJECTIVE:To investigate the effect of di (2-ethylhexyl) phthalate (DEHP) on the reproductive capacity of nematode Caenorhabditis elegans(C.elegans).METHODS:C.elegans cultures were organized into several groups:control (K solution) and three DEHP exposure groups:low (0.1 mg/L),medium (1.0 mg/L) and high (10.0 mg/L).Reproductive capacities were evaluated based on brood size,generation time and egg-laying rate/h.Dianamidophenylindole (DAPI) staining was used to observe the number of germline cells in the mitotic zone and the meiotic region of nematodes.Using transgenic MD701 nematodes,apoptotic cells in the pachytene zone were observed with the aid of fluorescence microscopy.RESULTS:Compared with control group,brood sizes of C.elegans were significantly decreased in the 1.0 mg/L and 10.0 mg/L exposed groups (P < 0.05),but had no significant effect on generation time (P>0.05).With the increase of exposure dose,the egg-laying rates were significantly decreased (P < 0.01) and showed a dose-effect relationship.In addition,the total number of germline cells and the number of germline cells in the mitotic region were significantly decreased in the 1.0 mg/L (P < 0.01) and 10.0 mg/L (P < 0.01) exposed group.The number of germline cells in the meiotic region also showed a downward trend.Compared with the control group,the germline cell numbers in the meiotic region were decreased significantly at 10.0 mg/L exposure concentration group (P < 0.01).With the increase of the dose,the germ cells showing apoptosis in the pachytene zone were also significantly increased (P < 0.01).CONCLUSION:DEHP caused arrest in mitotic proliferation and reduction in the number of germ cells in the meiotic zone.The observed toxicity was related to the increased number of apoptosis caused by DEHP in the pachytene of C.elegans.

Key words: DEHP, Caenorhabditis elegans, reproductive toxicity, oogenesis