Improvement of the comparative map of chicken chromosome 13.

A comparative map was made of chicken chromosome 13 (GGA13) with a part of human chromosome 5 (HSA5). Microsatellite markers specific for GGA13 were used to screen the Wageningen chicken bacterial artificial chromosome (BAC) library. Selected BAC clones were end sequenced and 57 sequence tag site (STS) markers were designed for contig building. In total, 204 BAC clones were identified which resulted in a coverage of about 20% of GGA13. Identification of genes was performed by a bi-directional approach. The first approach starting with sequencing mapped chicken BAC subclones, where sequences were used to identify orthologous genes in human and mouse by a basic local alignment search tool (BLAST) database search. The second approach started with the identification of chicken orthologues of human genes in the HSA5q23-35 region. The chicken orthologous genes were subsequently mapped by fluorescent in situ hybridisation (FISH) and/or single neucleotide polymorphism typing. The total number of genes mapped on GGA13 is increased from 14 to a total of 20 genes. Genes mapped on GGA13 have their orthologues on HSA5q23-5q35 in human and on Mmu11, Mmu13 and Mmu18 in mouse.