T(16: 17)43H translocation as a tool in analysis of the proximal part of chromosome 17 (including T-t gene complex) of the mouse

Abstract

SUMMARYLinkage relationships of three gene markers of chromosome 17, namely Brachyury (T), tufted (tf), and Histocompatibility-2 (H-2), to the break-point of T(16; 17)43H male sterile translocation were established. The following order was found: T−tf−T43H−H-2. In all cases the translocation break was found in cis to H-2k, haplotype, no recombinant being found among 218 backcross individuals examined. More than 60 viable and fertile animals trisomic for the proximal part of chromosome 17 (including T-t genetic complex) have been recovered among progeny of T43H/+ female translocation heterozygotes as a result of adjacent −2 disjunction at first meiotic division. Mutation tf has been assigned to band 17B in chromosome 17 by comparing the location of T190Ca and T43H genetic and cytological breakpoints. Recombination between centromere 17 and T43H break was reduced almost to zero in the presence of Rb(16.17)7Bnr translocation. The unexpected restoration of male fertility was observed in T43H/Rb7Bnr hybrids (T43H/+ males being completely sterile) which made it possible to prepare the first homozygotes for T43H male–sterile translocation. Direct estimation of chiasma frequencies in centromere 17−T43H region indicated an 11 cM distance between the centromere 17 and the proximal end of t12 haplotype. The significance of centromere −t (or H-2) distance on the predictable restrictions of the possible haploid manifestation of T-t or H-2 gene products on sperm membrane is discussed.