An albumin-like protein in the serum of non-parasitic brook lamprey (Lampetra appendix) is restricted to preadult phases of the life cycle in contrast to the parasitic species Petromyzon marinus

Previous work showed that the parasitic sea lamprey, Petromyzon marinus, ha s two different albumin-like serum proteins during the course of its life c ycle. One of these, AS, is the predominant protein in the serum of larval a nd metamorphosing intervals but is absent in the upstream migration phase o f the life cycle; the other, SDS-1, is found at its highest level in the up stream migration phase and is the predominant serum protein in this phase. The present investigation examines the nonparasitic brook lamprey Lampetra appendix for the presence of albumins. Using electrophoresis and antisera m onospecific for serum proteins, it was found that L. appendix has a serum p rotein that is antigenically similar to the AS protein of P. marinus. This protein (LAS) makes up about 70% of the total serum protein of the Lampetra larva, is present in metamorphic stages 1,2,3,4 and 5 but is virtually abs ent from the remaining metamorphic stages and the adult. Furthermore, the a dult of L. appendix has no serum protein that is antigenically similar to S DS-1 of the adult P. marinus; our study shows that, unlike P. marinus, ther e is no single protein that represents a major portion of the total serum p rotein content in the L. appendix adult. (C) 2000 Elsevier Science Inc. All rights reserved.