Enzyme-linked immunosorbent assay (ELISA) of vitellogenin in temperate basses (Genus Morone): Plasma and in vitro analyses

Blood levels of the egg yolk precursor vitellogenin (VTG) can be used as a definitive marker for the onset and progress of maturation in female teleos ts. In the present study, an enzyme-linked immunosorbent assay (ELISA) was developed to measure VTG in blood plasma from three species of temperate ba sses. The antigen capture, competitive ELISA is based on a rabbit antiserum raised against striped bass Morone saxatilis VTG and uses purified striped bass VTG as standard and in the final antigen capture step. The assay was validated fbr detecting VTG in the plasma of maturing female striped bass, white perch M. americana, and white bass M. chrysops. Serial dilutions of b lood plasma from vitellogenic females of all three species yielded VTG curv es that paralleled the standard curve in the ELISA, whereas no cross reacti vity was observed for plasma obtained from males of any Morons species. The working range of the ELISA was 33-1;118 ng/mL (90-10% of binding), and the intra- and interassay coefficients of variation (100 x SD/mean) at 50% bin ding were 3.8% (N = 20) and 5.94% (N = 4), respectively. Complete recovery (detection) in the ELISA was verified for a known quantity of VTG added to male striped bass plasma. Changes in plasma VTG concentrations during the a nnual reproductive cycle of female striped bass were measured both by ELISA and an established radial immunodiffusion assay (RIDA) based on the same a ntiserum and standard. Vitellogenin was detected in maturing females 7-8 mo nths prior to spawning and the correlation between individual VTG values me asured by ELISA and the RIDA was very high (r(2) = 0.95). The highly sensit ive and precise VTG ELISA should allow aquaculture and fisheries biologists to evaluate the gender and maturational status of individual fish of any M orone species during most of the year. Finally, VTG was detected by ELISA i n incubation medium following culture of white perch liver fragments with 1 x 10(-6) M estradiol-17 beta, providing the basis for an in vitro method t o study the physiology and toxicology of vitellogenesis in temperate basses .