Plant & Animal Genomes XI Conference

January 11-15, 2003
Town & Country Convention Center
San Diego, CA

Poster: Aquaculture
            

cDNA CLONING, PHYLOGENETIC ANALYSIS, AND EXPRESSION OF PROOPIOMELANOCORTIN (POMC) GENE FROM CHANNEL CATFISH (ICTALURUS PUNCTATUS)

¹ USDA-ARS Catfish Genetics Research Unit, Thad Cochran National Warmwater Aquaculture Center, PO Box 38, Stoneville, MS 38776, USA

² The Fish Molecular Genetics and Biotechnology Laboratory, Department of Fisheries and Allied Aquacultures and Program of Cell and Molecular Biosciences, Auburn University, Auburn, AL 36849, USA

Channel catfish (Ictalurus punctatus) proopiomelanocortin (POMC) cDNA was cloned to investigate its structure, evolution, and expression. POMC is one of the important genes in the hypothalamus-pituitary-adrenal axis, the main mediator of the stress response. POMC gene was isolated from a pituitary cDNA library and nucleotide sequence was determined. Deducted amino acid sequences were used to conduct phylogenetic analysis. The POMC cDNA is composed of 1164 bp and encodes a protein of 212 amino acids. POMC protein contains a signal peptide (SP, 1-28), N-terminal peptide (29-101), alpha-melanocyte stimulating hormone (alpha-MSH, 104-116), corticotropin-like intermediate lobe peptide (CLIP, 121-142), gamma-lipotropin (gamma-LPH, 145-158), beta-MSH (161-177), and beta-endorphin (beta-EP, 180-212). The channel catfish POMC protein does not contain gamma-MSH, and most of the joining peptide and part of the gamma-LPH are deleted. The highest similarity was observed with the carp (Cyprinus carpio) POMC II gene (67%), while the sea lamprey (Petromyzon marinus) POMC gene was the most divergent (17.9%). The average similarity was 47.6% among the 39 POMC genes from 31 different species analyzed. Real time PCR analysis detected a high level of POMC mRNA expression in catfish pituitary tissue. Overall architecture of channel catfish POMC is highly similar to those from other teleosts and it could be used for phylogenetic studies since it contains both the conserved hormone regions and the highly variable spacer regions.