Comparative analyses of serum vitellogenin levels in male and female Reeves' pond turtles ( Chinemys reevesii ) by an immunological assay

A quantitative immunological method was developed for measuring serum vitellogenin levels of Reeves' pond turtles ( Chinemys reevesii ) to investigate the effects of endocrine disruptors on the freshwater ecosystem. Vitellogenin was induced by injecting estradiol-17β into C . reevesii turtles (adult females, juvenile females, and males) and was purified from the turtle serum by EDTA-MgCl 2 precipitation followed by gel filtration. Using a polyclonal antibody raised against C . reevesii vitellogenin, an enzyme-linked immunosorbant assay was established. The detectable range, recovery of vitellogenin, and coefficient of variation in this assay were 0.0040–1.0 μg·ml −1 , 85.3–109% and 3.4–11.5%, respectively. This assay was also applicable for measurement of the concentrations of vitellogenins from other species, Japanese pond turtles ( Mauremys japonica ) and red-eared turtles ( Trachemys scripta ). The serum vitellogenin concentration of 131 C . reevesii turtles captured at a Japanese local river was measured by the assay. In females, vitellogenin ranged from 0.10 μg·ml −1 to 15,000 μg·ml −1 with two peaks, 0.10–1.0 μg·ml −1 (juveniles) and 1,000–10,000 μg·ml −1 (adults). However, in males, it ranged from 0.10 μg·ml −1 to 0.60 μg·ml −1 , showing one peak, 0.10–0.20 μg·ml −1 . Therefore, if relatively high concentrations of vitellogenin are detected in males or juvenile females, it is suggested that they would have been exposed to xenobiotic estrogens.