To gain insight into the reproductive toxicity of sublethal cadmium on marine polychaetes, Perinereis nuntia sandworms were exposed to cadmium via artificially contaminated seawater. Cadmium influence on sexual maturation, egg laying, fertilization, zygote hatching and vitellogenin expression levels were analyzed. Results indicated that 23.05 and 563.87 microg L(-1) cadmium significantly delayed sexual maturation. Fertilization rate was significantly inhibited by 563.87 microg L(-1) cadmium while lower concentrations showed no significant effect. Zygote hatching was significantly inhibited by cadmium concentrations greater than 1.12 microg L(-1). We identified a vitellogenin gene sequence in P. nuntia and found that mRNA transcription was significantly upregulated by cadmium. These results indicate that sublethal cadmium levels cause dose-dependent reproductive toxicity on P. nuntia by inhibiting sexual maturation, fertilization and zygote hatching, and the increased expression of vitellogenin suggesting cadmium has strong feminization effects on polychaetes.
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