FUNCTIONAL GENOMICS: PERFORMANCE TRAITS-LINKED DNA MARKERS AND NORMALIZED cDNA LIBRARIES IN CATFISH

Department of Fisheries and Allied Aquacultures, and Program of Cell and Molecular Biosciences, 203 Swingle Hall, Auburn University, Auburn, AL 36849

Genomics research has generated enormous amount of biological information. The processing and use of such information are dependent upon progress in functional genomics. In addition to comparative gene mapping for conserved biological functions and genomic domains, two alternative approaches have been used for functional analysis of genomes. Here I will present recent progress in catfish genomics on QTL mapping and EST analysis using normalized cDNA libraries. The selective genotyping approach was adopted to identify DNA markers linked to the performance traits of growth rate, feed conversion efficiency, and disease resistance to enteric septicemia of catfish (ESC). Over 100 microsatellite markers were analyzed. Putative linked DNA markers have been identified including three markers linked to the trait of feed conversion efficiency, one marker to growth rate, and one marker to disease resistance. Systematic analysis of linked markers using AFLPs is underway and progress will be presented. We have constructed normalized cDNA libraries using the following catfish tissues: spleen, leukocyte, head kidney, and skin. Our objectives are to lunch large-scale EST analysis to have insight into functional genomics in the disease processes to eventually identify genes that are turned on, off, up, and down-regulated after infection of Edwardsiella ictaluri (agent for the most damaging bacterial disease ESC), channel catfish virus, and Ichthyophthirius multifilis (agent for the Ich disease). The ultimate goal is to use the QTL and functional genomics information for genetic improvement of catfish brood stocks.