CATFISH GENOMICS RESEARCH AT USDA-ARS

USDA-ARS Catfish Genetics Research Unit Thad Cochran National Warmwater Aquaculture Center P.O. Box 38 Stoneville, Mississippi 38776

A genetic linkage map was produced consisting of 262 microsatellite loci (8 Type I and 254 Type II) genotyped in two reference families (USDA103 strain x Norris strain). The map consists of 34 linkage groups (n=29) covering 2008 cM of the catfish genome, and an average intermarker distance of 9.3 cM. Sex linkage was identified for several microsatellite loci. Multiplexed microsatellite loci were used to identify USDA103 strain fish against a background population of channel catfish from 20 commercial fingerling operations. This genotyping system may be used for strain certification upon release of the USDA103 catfish to the industry. A catfish Nramp cDNA was cloned that demonstrated higher sequence similarity with mammalian Nramp 2 but functional similarity to mammalian Nramp1.