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 plasmid
s and then cloned. The plasmids containing the parts of D-amino-acid oxidas
e gene were biotinylated and hybridized to human and mouse metaphase chromo
somes. The chromosomal slides were treated with fluorescein isothiocyanate
(FITC)-conjugated avidin. The hybridized signals were amplified with biotin
ylated anti-avidin antibody and FITC-avidin. The chromosomes were counter-s
tained with diamidino-phenylindole for assignment of the signal to a specif
ic band. Using this fluorescence in situ hybridization (FISH), D-amino-acid
oxidase gene was assigned to human chromosome 12q23-24.1 and mouse chromos
ome 5E3-F. Since these regions are syntenic between human and mouse, the pr
esent results indicate that the locus for this enzyme has been conserved th
rough evolution.