Paper Title
Effect Of Some Endocrine Disrupting Chemicals On The Sex-Ratio Of Caenorhabditiselegans

Abstract
Endocrine disrupting chemicals (EDCs) have been proved to concern on risk of ecosystem, wildlife and human health. Several biological assays and animal model have been developed to screen for the activities of the polluted EDCs. None of which has focused on the effects of EDCs on the sex-ratio of organism. This study proposed to use Caenorhabditis elegans as the model in laboratory system to screen for deleterious EDCs. Four types of EDCs were employed in the experiment including 4-Nonylphenol (NP), Tributyltin chloride (TBT), Triphenyltin chloride (TPT), and Testosterone (TS). Two sublethal concentrations were used; the LC20 (lethal concentration at 20% death) and half of the LC20 (LC20/2). Two incubating temperatures regimes were set up; at 22oC (normal culture condition) and at 33oC for 4hrs (male-induced temperature) and then continue at 22oC. The fourth larval stage (L4) of a multi-generation (P0 � F9) was grouped and incubated under the combination of the sublethal concentration and the temperature regimes system. The worms were exposed to the targeted EDCs for 4 generations, P0 to F3, and without EDCs thereafter for 5 generations, F6 to F9. Control groups were incubated under the 2 regimes of temperature without EDCs exposure. Results showed the higher sex-ratio in the groups of worm exposed to EDCs in both of the temperature regimes. The system also exhibited the important biological activities of the targeted EDCs including the concentration-dependent, time-dependent, generation-dependent, temperature-dependent manner and recovery. Keywords: Endocrine Disrupting Chemicals (EDCs), Nonylphenol (NP), Tributyltin chloride (TBT), Triphenyltin chloride (TPT), Testosterone (TS), sex-ratio, Caenorhabditis elegans