Complementation reactions of a lethal mouset-haplotype believed to include a deletion

Abstract

SUMMARYThe lethalt-haplotypes of the mouse fall into several distinct complementation groups, and varying degrees of partial complementation occur when haplotypes from different groups are crossed. The haplotypeth20arose as a mutant from the haplotypet6, and is thought to include a small deletion covering loci near thet-lethals. In this paper the complementarity ofth20was compared with that of its parent haplotypet6.th20showed weaker complementation thant6of the haplotypestw5,tw32andtw1. Hence the loci of these lethals were probably exposed by the deletion inth20. However,th20showed full complementation oftw18and showed full viability in compound with the dominant brachyury allele hairpin-tail,Thp. Therefore, theth20deletion probably does not overlap the presumed deletion inThp, nor extend to the locus of thetw18lethal. The significance of the weak complementation oftw5,tw32andtw1is discussed.