Narrowing the Critical Regions for Mouse t Complex Transmission Ratio Distortion Factors by Use of Deletions

Abstract

Abstract Previously a deletion in mouse chromosome 17, T22H, was shown to behave like a t allele of the t complex distorter gene Tcd1, and this was attributed to deletion of this locus. Seven further deletions are studied here, with the aim of narrowing the critical region in which Tcd1 must lie. One deletion, T30H, together with three others, T31H, T33H, and T36H, which extended more proximally, caused male sterility when heterozygous with a complete t haplotype and also enhanced transmission ratio of the partial t haplotype t 6, and this was attributed to deletion of the Tcd1 locus. The deletions T29H, T32H, and T34H that extended less proximally than T30H permitted male fertility when opposite a complete t haplotype. These results enabled narrowing of the critical interval for Tcd1 to between the markers D17Mit164 and D17Leh48. In addition, T29H and T32H enhanced the transmission ratio of t6, but significantly less so than T30H. T34H had no effect on transmission ratio. These results could be explained by a new distorter located between the breakpoints of T29H and T34H (between T and D17Leh66E). It is suggested that the original distorter Tcd1 in fact consists of two loci: Tcd1a, lying between D17Mit164 and D17Leh48, and Tcd1b, lying between T and D17Leh66E.