Plasma Vitellogenin and Estradiol Concentrations in Adult Gulf Sturgeon from the Pascagoula River Drainage, Mississippi
Gulf sturgeon Acipenser oxyrinchus desotoi are anadromous, the adults moving into rivers, by early spring for spawning and migrating back to salt water in the fall. Because Gulf sturgeon lack readily discernable secondary sex characteristics. minimally invasive means, such as evaluation of Plasma vitellogenin (an egg yolk protein precursor) and sex steroid hormones. have been used to determine gender. Our objectives were to explore the use of vitellogenin (Vtg) and estradiol (E2) to identify the gender of adult Gulf sturgeon captured in the Pascagoula River drainage and to determine whether these substances were useful in identifying which females would be spawning in a given spring. our enzyme-linked immunosorbent assay detected Vtg in all samples at concentrations ranging from 5.47 to 7,634.2 mu g/mL. For samples collected from March through May, the plasma Vtg concentrations generally Clustered into one of two groups, low (<100 mu g>/mL) and high (>1,000 mu g/mL). During the same months, Plasma E2 values followed a similar pattern of separation into low (<0.5-ng/mL) and high (>8-ng/mL) concentrations. Based on the clear delineation of Vtg and E2 concentrations in spring-captured sturgeon and comparison with previous Studies in which gender was definitively determined, fish with high Vtg (>1,000-mu g/mL) and high E2 (>8-ng/mL) concentrations were putatively identified as spawning females. The Plasma Vtg concentrations in 10 known males (based on the release of milt) were 13-86 mu g/mL. Our work provides the first information regarding Vtg and E2 concentrations for threatened Gulf sturgeon throughout the freshwater phase of their life cycle. It is currently unclear whether the Vtg concentrations measured in male Gulf sturgeon are within a normal range for this species in the wild or are a biomarker of endocrine disruption due 10 exposure to xenobiotic substances.