Sammendrag
Elevated levels of vitellogenin (Vtg) and zona radiata protein (Zrp) expression have proved to be sensitive biomarker of exposure responses to environmental estrogens. The conventional tissues for Vtg and Zrp gene and protein expression analysis in teleost fish are the liver and blood plasma. However, recent studies have indicated that Vtg and Zrp are also detectable in surface mucus of Atlantic salmon (Salmo salar) after exposure to xenoestrogens. These findings may represent potential non-invasive biomarker responses for assessing estrogenic potential of endocrine disrupting chemicals (EDCs). This study examines the biological significance of the presence of Vtg and Zrp in the skin of Atlantic salmon, and evaluates whether skin biopsy analyses may represent a non-lethal tool for assessing the hazard of EDCs in fish species. Juvenile Atlantic salmon were exposed to waterborne nonylphenol (NP) at 10 and 60 µg/L. Liver, plasma, surface mucus and skin samples were collected after 3, 7 and 10 days of exposure. Nonylphenol-induced Vtg, Zrp and estrogen receptor (ER) gene expression levels were determined in liver and skin tissue using RT-PCR with gene-specific primers. Levels of Vtg and Zrp gene expressions in the liver were modulated in a time- and nonylphenol concentration-specific manner. In skin tissue, Vtg gene expression did not show direct relationship to NP concentration, while Zrp gene expression levels showed a nonylphenol concentration-dependent increase (albeit non-significant). There was no obvious correlation between ER gene expression in skin and nonylphenol concentration, making this gene response less suitable as a biomarker of NP-exposure in fish skin tissue or biopsy.
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