Genetic markers in blue crabs (Callinectes sapidus) I: Isolation and characterization of microsatellite markers

Given the commercial and ecological importance of the dwindling Chesapeake Bay blue crab (Callinectes sapidus) fishery, there is a surprising scarcity of information concerning the molecular ecology of this species. The few studies published to date are based on allozyme data and indicate a single, panmictic population along the Atlantic coast. To address this shortcoming, we have initiated the development of genetic markers from both the nuclear and mitochondrial genomes of the blue crab. To this end, we performed two separate screenings of the blue crab nuclear genome using both dinucleotide and tetranucleotide repeat oligonucleotide probes and the highly efficient “FIASCO” (Fast Isolation by AFLP of Sequences COntaining repeats) methodology. Our screenings produced 34 microsatellite loci. Genotyping of a captive-mated pair of blue crabs and 30 of their offspring at 10 of our isolated loci shows that eight loci are inherited in true Mendelian fashion, with two loci being monomorphic. Additionally, we genotyped 102 blue crab DNA samples collected from different parts of the Chesapeake Bay with the same 10 loci. The results of these screenings, including heterozygosities ranging between 0.26 and 0.97, indicate that a majority of the loci isolated in our screen will ultimately be useful markers for population genetic studies. The molecular tools described in this paper will be used, in tandem with differences in the blue crab mitochondrial genome [Place, A.R., Feng, X., Steven, C.R., Fourcade, H.M., Boore, J.L., 2005. Genetic markers in blue crabs (Callinectes sapidus) II: Complete mitochondrial DNA sequence and characterization of variation. J. Exp. Mar. Biol. Ecol. 319, 15-27], to investigate potential genetic substructure within the Chesapeake Bay and across the entire Atlantic Coast/Gulf Coast range of the blue crab, as well as monitor the results of restocking hatchery-reared crabs into the Bay.