CHANGES IN SERUM IMMUNOGLOBULIN-M (IGM) CONCENTRATIONS DURING EARLY DEVELOPMENT OF CHUM SALMON (ONCORHYNCHUS-KETA) AS DETERMINED BY SENSITIVE ELISA TECHNIQUE

1. A specific and sensitive sandwich enzyme-linked immunosorbent assay (ELISA) was developed for the measurement of low levels of serum immu noglobulin M (IgM) of chum salmon Oncorhynchus keta. 2. In this assay, 5 mul serum was enough to measure the concentration of IgM and the mi nimum detectable concentration of serum IgM was about 5 ng/ml. 3. Coef ficients of variation within and between assays ranged from 2.90 to 9. 61%. 4. IgM concentrations remained at low level (< 300 ng/ml) until 4 0 days after hatching and then increased rapidly at the period of emer gence (48 days after hatching).