Assignment of D-amino-acid oxidase gene to a human and a mouse chromosome

A part of D-amino-acid oxidase gene was amplified in the human and mouse by polymerase chain reaction. The amplified fragments were ligated to plasmids and then cloned. The plasmids containing the parts of D-amino-acid oxidase gene were biotinylated and hybridized to human and mouse metaphase chromosomes. The chromosomal slides were treated with fluorescein isothiocyanate (FITC)-conjugated avidin. The hybridized signals were amplified with biotinylated anti-avidin antibody and FITC-avidin. The chromosomes were counter-stained with diamidino-phenylindole for assignment of the signal to a specific band. Using this fluorescence in situ hybridization (FISH), D-amino-acid oxidase gene was assigned to human chromosome 12q23-24.1 and mouse chromosome 5E3-F. Since these regions are syntenic between human and mouse, the present results indicate that the locus for this enzyme has been conserved through evolution.