LINKAGE OF THE CHICKEN MHC TO THE NUCLEOLUS ORGANIZER REGION VISUALIZED USING NONISOTOPIC INSITU HYBRIDIZATION

Linkage of the chicken major histocompatibility complex (B-complex) to the nucleolus organizer regions (NOR) has been confirmed in situ. Nonradioactive hybridization to metaphase chromosomes using a pool of biotinylated cDNA probes for the B-F, B-L-beta, and B-G genes of the B-complex gave positive signals on one or a pair of microchromosomes. Subsequent staining with silver nitrate proved these microchromosomes to be the NOR-bearing pair. The value of employing nonisotopic in situ hybridization techniques for mapping of genes and gene complexes, especially when dealing with microchromosomes, is stressed.