MAPPING THE BOVINE ALBINO LOCUS

The albino, beta-hemoglobin, and lactate dehydrogenase A (LDHA) loci c omprise a highly conserved syntenic group in those mammals in which th e three loci have been genetically mapped. In this study, we used a ty rosinase probe to map the bovine albino locus, using a panel of bovine -hamster hybrid cells in which HBB, LDHA, and a number of other loci h ad previously been mapped. The probe was a human tyrosinase cDNA clone (Pmel34) which has been mapped to the c (albino) locus in mice. Altho ugh beta-hemoglobin is linked to the albino locus in mice, rats, cats, and rabbits, the two loci are not syntenic in cattle. The tyrosinase probe, however, does hybridize to a fragment that is syntenic with lac tate dehydrogenase A in cattle. Since HBB is syntenic with catalase (C AT) in both humans and cattle, while catalase is asyntenic with HBB in mice, at least two chromosomal rearrangements are required to account for the chromosomal relationships of HBB, CAT, LDHA, and the albino l ocus in these three species.