Mapping the beta NGF gene in situ to a microchromosome in chicken

The chicken nerve growth factor (beta NGF) gene has been mapped by fluorescent in situ hybridization to a pair of microchromosomes, confirming previous reports of the existence of a single gene locus. A 39-kb genomic fragment cloned in a cosmid vector and including the 5' end of the beta NGF locus was biotinylated for nonradioactive detection of the gene. This report adds to the increasing evidence proving microchromosomal localization of highly conserved and biologically fundamental genes. The implications of such genes belonging to very small linkage groups for the transmission of alleles from generation to generation together with the relevance of nonisotopic in situ hybridization for avian gene mapping are considered.