Immunological study of muscle parvalbumin isotypes in three African catfish during development

Eleven parvalbumin isotypes expressed during the development of clariids Heterobranchus longifilis and Clarias gariepinus and claroteid Chrysichthys auratus were purified and electrophoresed on sodium-dodecyl-sulfate polyacrylamide gels. Immunochemical cross-reactions among these proteins were investigated by immunoblotting, using purified antibodies raised against three isotypes chosen at different stages of fish development. Antibodies raised against H. longifilis PA I (larval-juvenile isotype) and against C. gariepinus PA IIIa (juvenile-adult isotype) cross-reacted to a rather similar extent despite a weaker cross-reaction of anti-PA IIIa with larval-juvenile isotypes. On the other hand, antibodies raised against H. longifilis PA IV (an exclusively adult isotype) recognized markedly only H. longifilis PA IV and C. gariepinus PA IIIb. These two adult isotypes most likely belong to the alpha lineage, and all the others to the beta lineage. These results show that parvalbumin isotypes synthesized at different stages of fish growth differ structurally, and that the most marked difference is between larval-juvenile and adult clariid isotypes.