Plant & Animal Genome VI Conference Plant & Animal Genome VI Conference
P339
203 Swingle Hall, Department of Fisheries and Allied Aquacultures, Auburn University, Auburn, AL 36849
The potential of microsatellite sequences as genetic markers in catfish was investigated in respect to their abundance, genomic distribution, variability, inheritance, and usefulness in related species. Six small insert genomic DNA libraries enriched for six different families of microsatellites of channel catfish were constructed. These libraries contained about 50% clones positive with microsatellite probes. Hundreds of clones were isolated for characterization of microsatellite loci. 400 microsatellite clones containing (CA), (GA), (TAA) repeats were sequenced. 240 clones generated enough sequences for designing PCR primers. (CA)n was found to be most abundant in the channel catfish genome followed by (GA)n repeats. These microsatellites were evenly distributed in the genome of catfish. Polymorphism of microsatellites was measured by PCR amplification of individual locus using ten channel catfish strains. Most loci were polymorphic. To exploit microsatellite markers in construction of a genetic linkage map using the channel catfish x blue catfish hybrid system, we tested conservation of the microsatellite loci. Most of the 100 tested loci were conserved between the channel catfish and blue catfish. Conservation of microsatellite loci between these two closely related species make it possible to use all types of markers for construction of a genetic linkage map such as AFLP, RAPD, and microsatellites. Polymorphism levels were higher between the channel catfish and closely related blue catfish than among strains of channel catfish. Since much higher AFLP and RAPD polymorphism exists between the two species than among strains within channel catfish or blue catfish, application of AFLP, RAPD, along with these microsatellite markers will allow construction of a high density genetic linkage map in catfish.