RAP-PCR IDENTIFICATION OF DIFFERENTIALLY EXPRESSED GENES IN CHICKEN LINES DIVERGENTLY SELECTED FOR BODY WEIGHT AT EIGHT-WEEKS OF AGE

¹ Growth Biology Laboratory, Livestock and Poultry Science Institute, USDA-ARS, Beltsville, MD 20705 USA

² Department of Animal and Poultry Sciences, Virginia Polytechnic Institute and State University, Blacksburg, VA 24061 USA

White Plymouth Rock lines, divergently selected for body weight at eight-weeks of age (41 generations) provide a unique model population for identifying genes affecting growth in poultry. The body weights of these two lines, HWS (high weight selected) and LWS (low weight selected), differ by approximately eight-fold at selection age. Genes that are differentially expressed between the HWS and LWS lines were identified using RNA arbitrarily primed polymerase chain reaction (RAP-PCR) technique which provides a rapid and unbiased method for fingerprinting RNA gene transcripts. This technique was applied to total RNA isolated from the liver and skeletal muscle of HWS and LWS males. From this analysis over 50 differentially expressed genes were observed and subsequently isolated, cloned, and sequenced. Among these differentially expressed genes are key enzymes involved in glycolysis, gluconeogenesis, pro-hormone processing, and muscle fiber formation. Many of the cDNAs isolated have neither been previously described, nor have a known function in mammals. They may represent avian specific genes or novel factors that effect growth rate in general. Verification of the expression pattern for each of the isolated clones is being performed by Northern and RNAse protection assays. Identification of the genes influencing growth and metabolism in these lines may identify molecular genetic causes of the accelerated growth phenomenon observed in the modern broiler.