The proposed research is the continuation of a study using a combination of immunochemistry, protein chemistry, and molecular biology to ascertain the properties of immunoglobulins of primitive species and to identify and characterize the genes specifying them. Particular attention will be given to rearranging elements (variable, joining and constant regions), the multiplicity of these elements, and their arrangement. The focus of future studies will be: 1. characterization of Ig light chains of two carcharhine sharks, the tiger shark (Galeocerdo cuvieri) and the sandbar shark (Carcharhinus plumbeus) (elasmobranchs), and 2. completion of the characterization of genes of a teleost fish (the goldfish, Carassius auratus) that are homologous to human V beta gene sequences. One goldfish V beta homolog has already been characterized and will serve as a probe for screening of genomic and cDNA libraries of lower species and, potentially, of protochordates. Extremely little is known about the protein structure of shark light chains and nothing is known of the details of lamprey Ig or putative protoimmunoglobulins such as that found in the tunicate. Similarly, little is known about the genes encoding these proteins--the types of elements, their multiplicity, their sequence, and their arrangement. The goldfish V beta gene fragment described here represents the first example of the isolation of an Ig-like T cell receptor gene from a non-mammalian species. Immunoglobulin molecules belong to a family of proteins that are involved in self-recognition and self-defense in all vertebrates and possibly in some invertebrates. The best known member of the immunoglobulin family of molecules are the antibodies. The evolution of the immunoglobulins is not understood and, until recently, had been studied very little. The information to be obtained from this research will allow us to draw meaningful conclusions regarding the variable and constant region structure of immunoglobulins of primitive vertebrate species and should shed light upon the genetic events underlying the origins of this important family of molecules.
