MAPPING THE CHICKEN GENOME - PROBLEMS AND PROSPECTIVES

Various molecular methods are now used to map the chicken genome, incl uding chromosome scraping, flow cytofluorimetry, zonal centrifugation, construction of chromosome-specific libraries, genetic analysis with polymorphic DNA markers, and in situ hybridization. Two main drawbacks are characteristic of existing maps of chicken chromosomes. First, cl assic genetic maps (i.e., linkage groups of genes for morphological, p hysiological, and biochemical characters), physical maps of chromosome s, and new genetic maps constructed on the basis of polymorphic DNA ma rkers (RFLP, RAPD, VNTR, SSR, and CR1-PCR) do not coordinate with one another. Second, a relatively low number of genes is present in classi c genetic maps and physical chromosome maps. Application of cytogeneti c methods to chromosome mapping in birds is limited because of some sp ecific features characteristic of the organization of avian genomes. F or the same reason, studying the location and expression of avian gene s is very important. Since mammalian and avian genomes differ in struc ture, revealing their possible common functional characteristics will provide for a better understanding of the general mechanisms that cont rol biologically important characters in higher animals.