title: Molecular and cellular detection of expression of vitellogenin and zona radiata protein in liver and skin of juvenile salmon (Salmo salar) exposed to nonylphenol.
abstract: In developing bioassays for estrogenic effects, vitellogenin (Vtg) induction and zona radiata protein (Zr-protein) induction in males and juveniles of oviparous vertebrates have been used as sensitive biomarkers for estrogenicity. Nonylphenol (NP) produces similar and parallel expression patterns of Vtg and Zr-protein levels in plasma and surface mucus of salmon, the response being concentration- and time-dependent. We have explored the potential mechanisms of Vtg and Zr-protein expression in surface mucus by comparative molecular and cellular approaches. Liver, skin, blood, and surface mucus samples were collected from fish exposed to a single waterborne concentration of NP (10 and 60 microg/l), 3, 7, and 10 days post-exposure, for gene expression analysis (liver and skin; quantitative real-time polymerase chain reaction) and protein analysis (blood and surface mucus; enzyme-linked immunosorbent assay). Protein expression was localized by immunohistochemistry. NP produced concentration- and time-dependent increases of hepatic estrogen receptors (ERalpha and ERbeta), Vtg, and Zr-protein mRNA and plasma protein levels. These responses paralleled cellular detection of Vtg and Zr-protein in the liver with unique expression patterns in the cytoplasm of hepatocytes, hepatic sinusoids, and endothelial cells. ERalpha, Vtg, and Zr-protein mRNA were detectable in the skin. ERbeta was the only skin response that was NP-concentration-dependent, especially at day 10 post-exposure. Immunohistochemistry for Vtg and Zr-protein in skin showed unique expression patterns in mucus vacuoles, epidermal cells, and scales in an NP-concentration- and time-specific manner. Thus, analysis of skin mRNA levels for xenoestrogen biomarker responses is a less-promising approach than protein analysis. The immunohistochemical localization of Vtg and Zr-protein levels in the skin further validates surface mucus as a sensitive biomarker source for estrogenic compounds. These responses represent an improvement for the detection of endocrine-disrupting compounds and related pollutants in the environment.
authors.affiliation: Department of Biology, Norwegian University of Science and Technology (NTNU), Høyskoleringen 5, Trondheim, Norway. arukwe@bio.ntnu.no
authors.forename: Augustine
authors.initials: A
authors.lastname: Arukwe
authors.forename: Kjersti
authors.initials: K
authors.lastname: Røe
mesh_terms: D000818:Animals; D003593:Cytoplasm / Q000378:metabolism; D004527:Egg Proteins / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D042783:Endothelial Cells / Q000187:drug effects / Q000378:metabolism; D004785:Environmental Pollutants / Q000633:toxicity; D004817:Epidermis / Q000187:drug effects / Q000378:metabolism; D047628:Estrogen Receptor alpha / Q000235:genetics; D047629:Estrogen Receptor beta / Q000235:genetics; D015870:Gene Expression / Q000187:drug effects; D022781:Hepatocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008099:Liver / Q000187:drug effects / Q000378:metabolism*; D010636:Phenols / Q000494:pharmacology*; D020317:Salmo salar / Q000097:blood / Q000235:genetics / Q000378:metabolism*; D012867:Skin / Q000187:drug effects / Q000378:metabolism*; D014819:Vitellogenins / Q000097:blood / Q000235:genetics / Q000378:metabolism*
chemical_list: D004527:Egg Proteins; D004785:Environmental Pollutants; D047628:Estrogen Receptor alpha; D047629:Estrogen Receptor beta; D010636:Phenols; D014819:Vitellogenins; C423083:zona radiata protein, fish; C041594:4-nonylphenol