ABSTRACT
Adult axolotls (A. mexicanum) were hyperimmunized with the haptenic determinant, azobenzene-arsonate (ARS). Specific antibodies were isolated from their serum by immune-affinity chromatography on immobilized ARS columns. Analysis of the specific ARS-binding molecules by sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicated that these animals were capable of producing both high molecular-weight (presumably IgM) and low molecular-weight antibodies to the ARS hapten. The low molecular-weight anti-ARS antibody produced by one inbred colony of axolotls did not show any restricted heterogeneity, as assessed by isoelectric focusing. Our results suggest that regulatory events, not the absence of genetic information, may be responsible for the apparent lack of Ig isotype diversity in this species.