“…After centrifugation, serum volumes (2-10 lL) were obtained from individual adult zebrafish, and subsequently diluted in phosphate-buffered saline (PBS) and frozen at À80°C until analysis. Vtg was purified from serum of E2-induced zebrafish according our previous work Song et al, 2005), and used as a standard after identification and quantification. Serum vtg levels were determined using a comparative enzyme-linked immunosorbent assay (ELISA) .…”