USDA-ARS Catfish Genetics Research Unit Thad Cochran National Warmwater Aquaculture Center P.O. Box 38 Stoneville, MS 38776
A genetic linkage map of the channel catfish genome (n=29) was constructed from two reference families. The reference families were reciprocal matings of USDA103 strain x Norris strain catfish, and 72 offspring were genotyped from each family. Microsatellite loci were identified in channel catfish DNA sequences in GenBank or by cloning from a small insert genomic DNA library. Duplicate loci were detected using the FASTA program. PCR-amplified microsatellite fragments were electrophoresed on an ALFexpress DNA Analysis System (Pharmacia), and fragment size was determined using Allelinks software (Pharmacia). Twopoint genetic linkage between markers at LOD > 3.0 was determined with CRI-MAP v2.4, and linkage groups were constructed using the ALL and FLIPS options. The CHROMPIC option was used to identify unlikely double crossovers, and genotypes causing double crossovers were rescored from new PCR amplifications. A total of 293 microsatellite loci were polymorphic in one or both families, with an average of 167 informative meioses per locus. Eight Type I and 254 Type II loci were placed in 34 linkage groups covering 2008 cM, while no linkage was detected for 4 Type I and 27 Type II loci. Linkage groups ranged in size from 6.3 to 136.1 cM (avg. 59.0), with an average intermarker distance of 9.3 cM. There was no recombination between five microsatellite loci and the sex determining locus. This genetic linkage map will provide a template for genetic studies of channel catfish.
Plant & Animal Genome VIII Conference Plant & Animal Genome VIII Conference