Characterization of the Polymeric Immunoglobulin Receptor in Leucoraja erinacea

The immune system is essential in protecting organisms against infectious diseases. The mucosal immune system protects mucosal membranes, such as those lining the respiratory and intestinal tracts, which are typical entryways for pathogens (such as viruses & bacteria). An important component of the mucosal immune system are antibodies, which are produced as a defense mechanism in response to pathogens. The antibodies are transported across mucosal membranes by the polymeric immunoglobulin receptor (pIgR). Both antibodies and pIgR are highly conserved throughout vertebrate evolution, and have been identified in mammals, reptiles, birds, amphibians, and bony fish. Antibodies have been characterized in cartilaginous fish in intestinal secretions, however, the pIgR has not. Hence, we hypothesize that pIgR is presence in cartilaginous fish, to transport these antibodies for protection against pathogens. We have identified a partial cDNA sequence that has similarities to pIgR in other species. My project is to characterize the sequence and expression pattern for this gene in Leucoraja erinacea, the little skate, a cartilaginous fish. I am using a PCR technique called 5? Rapid Amplification of cDNA Ends to obtain the full-length sequence. Through semi-quantitative PCR, I am characterizing expression patterns of this gene in the various tissues of the little skate to see if the expression of our gene is consistent with pIgR function. The polymeric immunoglobulin receptor in the little skate, a cartilaginous fish, is of interest, because skates are representative of the most primitive vertebrate species with antibodies, hence providing insight on the origins of the immune system