The objective of the present study was to survey estrogenic activities incoastal aquatic environments in China. In this survey, we utilizedproduction of vitellogenin (Vg), a major estrogen-sensitive, liver-derivedserum precursor of egg yolk in red lip mullet(Liza haematocheila) as amarker for the detection of estrogenic activities; both serum and hepaticexpression of Vg were quantified. A specific and sensitive chemiluminescent immunoassay (CLIA) wasdeveloped for quantification of a major vitellogenin (Vg) subtype (B-typeVg; VgB) in the serum of red lip mullet. The mullet VgB CLIA wasperformed using two-site method, with subtype-specific antiserumdeveloped for purified red lip mullet VgB (a-VgB). Assay conditions wereoptimized with regard to antibody concentration, as well as incubation time,resulting in the typical assay ranging from 3.91 to 500 ng/ml. Dilution ofvitellogenic female mullet and the serum from estrogen-treatedjuvenile mullet appeared to be parallel to purified mullet Vg, while dilutionof male mullet serum hardly revealed any positive immunoreactivity in thedeveloped CLIA. Serum levels of VgB were quantified in 10 individuals ofred lip mullet reared in an aquaculture center in Tianj in city, China. Infemales (n=9), production of VgB was evident but varied in their serumwith the levels ranging from 3.0 to 2700.1μg/ml, showing a typicalof increase during the ovarian growth. In contract, serum level of VgB in amature male mullet was extremely low(2.7μg/ml), indicating no sign ofestrogenic activities in this environment. In addition,no trace of gonadalabnormality was evident when histological observation was performed forall individuals. The present study provided a new tool for the quantificationof the major estrogen-inducible biomarker (i.e., VgB) in red lip mullet,which appeared to be better in the sensitivity in comparison with ourprevious assay and thus enable us to evaluate a variety level of estrogenicactivities in aquatic environment. Basic information such as typical, albeitpreliminary and reproductive changes in circulating VgB levels were alsoprovided and will endow to set a "normal" baseline, which is necessary tobe established prior to interpreting "abnormal" inductions of this biomarker. The qPCR assay for the quantification of VgB in this species is alsodescribed and validated. A gonadal abnormality (i.e., formation oftestis-ova) wasfound in one out of 40 juvenile individuals caught fromthree different estuary areas around the mouth of the Yangtze River, China.Serum and hepatic expression of VgB were non-detectable or barelydetectable, indicating the surveyed areas were currently not estrogenic.These results suggest that 1) the influence of estrogenic activities on thetestis-ova formation may have occurred earlier and remained evident as amorphological abnormality, while abnormal Vg expression is no longerdetectable, and/or 2) chemical contaminants other than estrogenic EDCsmight have caused this gonadal abnormality.