Radioimmunoassay for Silver Carp Gonadotropin

Abstract

A radioimmunoassay for cyprinid gonadotropin (GtH) was developed using GtH purified from the silver carp Hypophthalmichthys molitrix and its specific antiserum. The minimum detectable quantity of silver carp GtH was 0.58 ng/m/ (29 pg/tube). The intraassay and the inter-assay coefficients of variation were 6.8% (N=6) and 8.6% (N=5), respectively near 50% binding. This system was found to be suitable for the measurement of plasma GtH of goldfish Carassius auratus and carp Cyprinus carpio and pituitary GtH of some teleosts. The competition curves for goldfish and carp plasma were parallel to the standard curve with silver carp GtH. Pituitary extracts of goldfish, carp, honmoroko Gnathopogon elongatus, medaka Oryzias latipes, and chichibu goby Tridentiger obscurus showed competition curves parallel to the silver carp GtH standard, but plasma and pituitary samples of bitterlings (Cyprinidae) showed less steep curves than the standard. This system was physiologically validated by detecting the ovulatory GtH surge in individual goldfish. Plasma steroid hormone levels during ovulation were also measured and their role were discussed in relation to the GtH surge. © 1985, The Japanese Society of Fisheries Science. All rights reserved.