Plasma levels of vitellogenin and eggshell zona radiata proteins in 4-nonylphenol and o,p′-DDT treated juvenile Atlantic salmon (Salmo salar)

Induction of vitellogenin (Vtg) in males and juveniles of oviparous vertebrates has been used as a biomarker for xenoestrogens. Recently,, we have demonstrated that synthesis of eggshell zona radiata proteins (Zrp) or zonagenesis is an integral aspect of fish oogenesis (Oppen-Berntsen et al. (1994) Journal of Experimental Zoology 268, 59-70), and that Zrp synthesis is a sensitive biomarker for nonylphenol (Arukwe et al. (1997) Environmental Health Perspective 105, 418-422). This study, compares the responses of Vtg and Zrp in plasma of juvenile Atlantic salmon (Salmo salar) treated with 4-nonylphenol (NP) and o,p'-DDT (both at 25 mg kg(-1), singly and in combination). Validated ELISA and immunoblot analysis show that Vtg and Zrp respond significantly stronger to NP treatment alone and in combination with o,p'-DDT compared to control and o,p'-DDT treatment alone. However, a slight reduction in NP-induced Zrp levels was indicated when NP was injected in combination, with o,p'-DDT (C) 1998 Elsevier Science Ltd. All rights reserved.