LOSS OF HINDIII CLEAVAGE SITES IN THE D-AMINO-ACID OXIDASE GENE IN SOME INBRED STRAINS OF MICE

D-Amino acid oxidase cDNA was amplified by a polymerase chain reaction using RNA extracted from the mouse kidney. When digested with HindIII , the cDNAs of the BALB/c and ddY/DAO(-) mice were cleaved into two fr agments whereas the cDNA of the ddY/DAO(+) mice was not. Sequencing re vealed that nucleotide-471 of the cDNAs was G in the BALB/c and ddY/DA O(-) mice whereas it was substituted for C in the ddY/DAO(+) mice. Thi s base substitution was the cause of the failure of the cleavage of th e cDNA of the ddY/DAO(+) mice. Examination of other strains of inbred mice showed that D-amino-acid oxidase cDNAs of A/J, AKR, C57BL/6, CD-1 , CF#1, ICR, DBA/2, NZB and NZW mice were cleaved with HindIII into tw o fragments whereas those of C3H/He, CBA/J and NC mice were not. Genom ic DNAs extracted from the mice of these 15 strains were digested with HindIII and hybridized with D-amino-acid oxidase cDNA. A 18.2-kb frag ment hybridized with the probe in the C3H/He, CBA/J, ddY/DAO(+) and NC mice whereas two fragments of 12 kb and 6.2 kb hybridized in the othe r mice. These results are consistent with those of the cDNAs, confirmi ng the loss of the HindIII cleavage site in the C3H/He, CBA/J, ddY/DAO (+) and NC mice. The Southern hybridization revealed a loss of a diffe rent HindIII cleavage site in the A/J, AKR, C57BL/6, DBA/2, ICR and NZ B mice. The substitution at nucleotide-471 should cause a substitution of an amino acid residue. However, this substitution did not affect c atalytic activity of D-amino acid oxidase.