Effects of 4-Nonlyphenol Exposure on P. olivaceus and S. schlegeli Vitellogenesis

Abstract

The effects of the estrogenic compound 4-nonylphenol (4-NP) on vitellogenesis in juvenile olive flounder ( Paralichthys olivaceus ) and rockfish ( Sebastes schlegeli ) exposed continuously at 10, 50 and 100μgℓ−1 levels for 7 days were compared. The expression of VTG mRNA level and protein using specific probes were examined. The levels of plasma estradiol-17 β(E2) and testosterone (T) were assessed by radioimmunoassay (RIA). Plasma E2 concentrations increased significantly in two female fish species exposed to 100μgℓ−1 of 4-NP over concentrations in control fish. Plasma T concentrations increased in P. olivaceus . Four days after exposure, the level of VTG mRNA expression increased in P. olivaceus and S. schlegeli exposed to 20μgℓ−1 of 4-NP. In addition, plasma VTG protein expression was seen in P. olivaceus and S. schlegeli . In S. schlegeli and P. olivaceus exposed to 4-NP, the changes were noticed mainly in hepatocytic vaculation after 7 days of exposure. Thus, 4-NP may disrupt vitellogenesis in immature fish both directly and indirectly via disrupted steroidogenesis and liver pathology. Immature S. schlegeli were the most sensitive to 4-NP exposure in vitellogenesis.