DELETION MAPPING BY IMMUNOSELECTION AGAINST THE H-Y HISTOCOMPATIBILITY ANTIGEN FURTHER RESOLVES THE SXR(A) REGION OF THE MOUSE Y-CHROMOSOMEAND REVEALS COMPLEXITY OF THE HYA LOCUS

A genetic map of the mammalian Y chromosome cannot be produced by stan dard Mendelian methods because the Y does not participate in meiotic e xchange over the majority of its length. However, deletion mapping of the mouse Y chromosome is facilitated by the fact that its short arm c arries the histocompatibility-Y (Hya) locus. This locus encodes male-s pecific (H-Y) antigens that can be selected against in tissue culture by the technique of immunoselection. To produce cells carrying deletio ns, cytotoxic T lymphocytes (CTLs) specific for H-Y antigens were cocu ltured with a lymphoblastoid cell line derived from a mouse carrying t he portion of the short arm defined by the Sxr(a) translocation on the distal end of its X chromosome. H-Y antigen-loss variant cells that c ontained Y-specific deletions were identified. Molecular, karyotypic, and immunological analysis of the deletion variants allowed us to defi ne up to 16 ordered intervals and suggested an overall organization of Sxr(a). The analysis also suggests that at least two and up to five d istinct loci encode H-Y antigens. (C) 1994 Academic Press, Inc.