Association of the lethal yellow (Ay) coat color mutation with an ecotropic murine leukemia virus genome

The dilute (d) coat color mutation on chromosome 9 is closely associated with an ecotropic murine leukemia virus (MuLV) genome [Jenkins, N.A., Copeland, N.G., Taylor, B.A. & Lee, B.K. (1981) Nature 293, 370-374]. DBA/2J mice homozygous for the reverse mutation to wild type at the dilute locus (d+2J) lack ecotropic virus-specific sequences, suggesting that the dilute mutation was caused by virus integration. In the experiments described here, we analyzed the ecotropic MuLV DNA content of mice that collectively carry 10 different alleles at the agouti coat color locus (of chromosome 2) to determine whether any of these alleles also are associated with ecotropic virus sequences. Of the 10 alleles analyzed, one allele, lethal yellow (Ay), which is carried congeneically and heterozygously on C57BL/6J, 129/Sv, and LT/Sv mice, was closely associated with an ecotropic MuLV provirus. The close association of this provirus with the Ay allele suggests that this mutation also may be caused by virus integration. Furthermore, this association may be useful for molecular cloning and characterizing the many alleles at this locus.