Immunologic methods for species identification of early life stages of lutjanid fishes from the western central Atlantic. Part I: Characterization of an interspecies protein

A 66 kDa glycoprotein selected from SDS-PAGE gel profiles of soluble extracts of Lutjanus griseus was purified by Fast Protein Liquid Chromatography technology. A polyclonal antiserum produced to the single- chained glycoprotein was tested with 14 other lutjanid extracts in Western blots and produced 3 different patterns: strong reactions with L. jocu and L. apodus; weak reactions with L. buccanella, L. synagris, L. analis, L. campechanus, Pristipomoides aquilonaris, Ocyurus chrysurus, and Apsilus dentatus; no reactions with L. vivanus, L. mahogoni, L. cyanopterus, Etelis oculata, and the hybrid L. synagris x O. chrysurus. The anti-66 kDa antiserum also reacted strongly with soluble extracts of oocytes and juveniles of L. griseus. Adsorption of the IgG fraction of the antiserum with glutaraldehyde- insolubilized L. apodus extract resulted in an antiserum that remained strongly reactive with L. griseus extract but that was weakly reactive with L. apodus extract and negative with L. jocu extract in Western blots. The N- terminal amine acid sequence analyses of the first 10 residues of the purified 66 kDa proteins of L. griseus and L. jocu were approximately the same, but only 3 of 10 residues were the same with the purified proteins of L. griseus and L. apodus. Extracts of L. apodus contained 3 additional proteins that were not detected in extracts of L. griseus as determined by SDS-PAGE. This evidence for both interspecies and species-specific protein determinants is currently being used to produce species-specific polyclonal and monoclonal antisera for identifying species of lutjanid fishes at early life history stages.