2006 Annual Report 4d.Progress report. This report documents research conducted under a Reimbursable Cooperative Agreement with University of Mississippi. Additional details can be found in the report for the inhouse project, 6402-31000-008-00D, Catfish Genetics, Breeding, and Physiology. The objective of this cooperative research project is to identify DNA clones containing the catfish immunoglobin heavy chain locus, sequence these clones, and establish the gene structure in this locus. High-throughput genomics technology was used to determine the DNA sequence of large insert DNA clones that contained the immunoglobulin gene. The immunoglobulin region spanned more than 250,000 bp and contained 70 genes. This project provides information on the structure of the gene encoding a major component of catfish antibodies which will assist researchers in understanding how the catfish immune system functions. Also it will be useful in determining how these molecules have developed in more advanced species.