Supawadee Poompuang

A preliminary genetic map of walking catfish (Clarias macrocephalus)

We have constructed the first linkage map for walking catfish, Clarias macrocephalus, using amplified fragment length polymorphism (AFLP) markers. Forty-seven primer combinations were used to amplify DNA samples of a female C. macrocephalus and 79 haploid embryos. The AFLP map consists of 134 loci placed into 31 linkage groups, with 12 loci remaining unlinked. The number of markers per linkage group varies from 3 to 14. The map spans an estimated 2037.4 Kosambi cM, with an average spacing of 17.07 cM. This linkage map will provide the basis for a high-resolution map for walking catfish.

Sixteen EST-linked microsatellite markers in Günther's walking catfish, Clarias macrocephalus.

Twenty‐seven new microsatellite sequences were identified by screening 2029 expressed sequence tags from Günthers walking catfish, Clarias macrocephalus. Sixteen loci were polymorphic with the number of alleles ranging from two to 16 per locus and the observed and expected heterozygosities ranging from 0.4667 to 0.9333 and from 0.427 to 0.8819 per locus, respectively. Cross‐species amplifications of all 16 primer pairs were tested in four other species of catfish including Clarias gariepinus, Pangasius hypophthalmus, Pangasius larnaudii and Pangasianodon gigas. Eleven loci were found to amplify in other species, with the number of polymorphic loci ranging from one in P. larnaudii to nine in C. gariepinus.