RIA for salmon IGFBP

Salmon plasma contains at least three insulin-like growth factor binding proteins (IGFBPs) with molecular masses of 41, 28 and 22 kDa. The 41-kDa IGFBP is similar to mammalian IGFBP-3 in size, type of glycosylation and physiological responses. In this study, we developed a radioimmunoassay (RIA) for the 41-kDa IGFBP. The 41-kDa IGFBP purified from serum was used for antibody production and assay standard. Binding of three different preparations of tracer were examined; 125I-41-kDa IGFBP, 125I-41-kDa IGFBP cross-linked with IGF-I (125I-41-kDa IGFBP/IGF-I) and 41-kDa IGFBP/125I-IGF-I. Only binding of 41-kDa IGFBP/125I-IGF-I was not affected by added IGFs, and therefore it was chosen for the tracer in the RIA. Plasma 41-kDa IGFBP levels measured by RIA were increased by growth hormone treatment (178.9 ± 4.9 ng/ml) and decreased after fasting (95.0 ± 7.0 ng/ml). The molarities of plasma 41-kDa IGFBP and total IGF-I were comparable, and they were positively correlated, suggesting that salmon 41-kDa IGFBP is a main carrier of circulating IGF-I in salmon, as is mammalian IGFBP-3 in mammals. During the parr-smolt transformation (smoltification) of coho salmon, plasma 41-kDa IGFBP levels showed a transient peak (182.5 ± 10.3 ng/ml) in March and stayed relatively constant thereafter, whereas IGF-I showed peak levels in March and April. Differences in the molar ratio between 41-kDa IGFBP and IGF-I possibly influence availability of IGF-I in the circulation during smoltification

Effect of mercury on glutathione and thyroid hormones

10.1007/BF01700885Bulletin of Environmental Contamination and Toxicology444616-622BECT