Quantitative changes in a serum protein,AS, during the life cycle of the lamprey,Petromyzon marinus L.

The electrophoretically fastest migrating protein in ammocoete serum, AS protein, was isolated and found to be an acidic glycoprotein with a molecular weight of 140,000 Daltons. Purified AS was injected into rabbits to produce a monospecific antiserum that was used in rocket immunoelectrophoresis to quantitate AS at different periods in the life cycle. AS was found to constitute approximately 70% of total serum protein in the ammocoete, remained at about the same value during transformation, and was reduced to 38% of total serum protein in the juvenile adult. In both male and female upstream migrant animals, AS was less than 0.5% of total serum protein. When juveniles were acclimated to seawater over a 10 week period, it was found that their AS level was reduced by 92% to 3.8% of total serum protein. These results are discussed in relation to changes in other serum proteins at various intervals of the lamprey life cycle.