Isolation and partial characterization of IgM-like immunoglobulins from the serum of carp (Cyprinus carpio L.), frog (Rana ridibunda Pall.) and tortoise (Testudo graeca Pall.).

1. IgM-like immunoglobulin fractions have been isolated by combinations of precipitation procedures and gel-filtration from the serum of three vertebrate species, representative of the classes of Pisces (Cyprinus carpio L.), Amphibia (Rana ridibunda Pall.) and Reptilia (Testudo graeca Pall.). 2. The homogeneity of the isolated fractions has been confirmed electrophoretically and immunoelectrophoretically. 3. Electrophoretic mobility of IgM, similar for the three species studied has been observed in polyacrylamide gel; in agar gel immunoelectrophoresis carp and frog IgM mobilities are almost identical, in contrast to the markedly slower cathodic migration of tortoise IgM.