Avidin and ovalbumin induction by progesterone in chicken oviduct detected by sensitive immunoenzymometric assays.

This study describes sensitive immunoenzymometric assays (IEMAs) for chicken avidin and ovalbumin, markers of cytodifferentiation and action of progesterone and oestrogen in the oviduct magnum mucosa. The determination range was 0.5-100 ng/ml and the detection limit 0.1 ng/ml in both IEMAs. The intra- and interassay coefficients of variation, measured from chicken tissue supernatants, averaged below 6 and 10% respectively. IEMAs correlated well with the radioimmunoassays for avidin and ovalbumin previously developed in our laboratory, and with the widely used [14C]biotin-binding method for avidin. Using an IEMA, we found avidin induction with low concentrations of progesterone in the differentiated oviduct of oestrogen-pretreated chicks. The induction has not been detected previously by less sensitive methods. Avidin was induced by all given doses of progesterone (0.2-200 mg/kg in vivo for 24 h after a short oestrogen treatment), the response being dose-dependent at doses of 0.2-20 mg progesterone/kg body weight, the maximum avidin production being about 70 micrograms/g tissue. Ovalbumin was induced at doses of 2-200 mg progesterone/kg body weight without variations in the responses, being about 35 mg/g. The mean content of avidin in the oviduct of laying hens was 58.1 micrograms/g, and of ovalbumin 74.9 mg/g. Minimal traces of avidin and ovalbumin were found in the oviduct after hatching (0.3 and 5 micrograms/g respectively); however, progesterone did not have an effect on this expression. Sensitivity, rapidity and practicability, together with non-radioactivity, are the main advantages of the present IEMAs for chicken avidin and ovalbumin.