Vitellogenin of the Chilean flounder <Emphasis Type="Italic">Paralichthys adspersus</Emphasis> as a biomarker of endocrine disruption along the marine coast of the South Pacific. Part I: induction,purification, and identification

We sought to provide a useful indicator of the presence of endocrine-disrupting contaminants along the marine coast of the South Pacific using Chilean flounder (Paralichthys adspersus). In light of the lack of information on vitellogenin for this species, we induced, purified, and identified the plasma vitellogenin of Chilean flounder inhabiting the Chilean coast. Vitellogenin (Vg) from Chilean flounder was purified by size exclusion and ion-exchange chromatography using plasma from juvenile males induced by injecting 17β-estradiol. The Vg was detected by SDS–PAGE and Western blot analyses using an antibody against turbot (Scophthalmus maximus) vitellogenin. These analyses revealed a protein band of 205 kDa and three minor bands of 120, 90, and 68 kDa. These proteins were identified as Vg by means of mass spectrometry (LCQ Duo ESI-IT-MS), matching sequences of tryptic peptides to known sequences for several other fish species. The matches showed the presence of vitellogenin (VgI, VgII, Vg A and Vg B) in Chilean flounder, similar to species such as mummichog (Fundulus heteroclitus), Japanese medaka (Oryzias latipes), and white perch (Morone americana). These results are discussed in terms of identifying Vg in Paralichthys adspersus with the antibody to turbot Vg. Moreover, we compare the molecular size of Vg from Chilean flounder (large) with that of other flatfish species. Finally, we discuss the potential use of this molecule as a biomarker for the presence of xeno-estrogenic compounds along the Chilean coastline.