Electrophoretic determination of estrogen-induced protein in fish exposed to synthetic and naturally occurring chemicals.

In a first step we investigated whether Leuciscus idus, a fish routinely used to assess the quality of surface water in Germany, is suitable to indicate the presence of endocrine-disrupting chemicals. An electrophoretic method was used to determine estrogen-induced protein in fish serum (presumed vitellogenin). This method was tested by exposing juvenile L. idus to 17 alpha-ethinylestradiol, 17 beta-estradiol and estrone. Nominal concentrations of the steroid were compared with concentrations determined analytically by using GC/MS techniques. Under flow-through conditions, 7 days of exposure to 6 ng/l EE2 significantly induced serum vitellogenin in juvenile L. idus. In juvenile rainbow trout (Oncorhynchus mykiss) 4 ng/l EE2 induced significantly elevated levels of serum vitellogenin. In Danio rerio oral application of 40 micrograms 4-nonylphenol/fish per day during a 3-week exposure period caused a major increase of serum vitellogenin. Physiological protein induction could also be measured in Abramis brama, Cyprinus carpio, Oncorhynchus mykiss, Perca fluviatilis, Rutilus rutilus obtained from natural habitats and in Rhodeus sericeus. The minimum amount of blood required for electrophoretic analysis was 1 microliter which should allow monitoring of small sized fish species as well as juvenile fish.