Close linkage of a transgene insertion site to the steel (Sl) locus on mouse chromosome 10

Abstract

The characterization of the insertion sites of exogenous sequences in transgenic mice can identify loci that are potentially useful for the genetic analysis of the mammalian genome. We have found that the transgene insertion site in the transgenic line TG.EB is tightly linked with the Steel (Sl) locus on mouse chromosome 10. In a backcross between doubly heterozygous transgenic Sl (Tg.EB +/+ Sl) mice and wild-type mice, only one recombinant was found in 135 progeny (recombination percentage = 0.7 +/- 0.7). The recombination frequency of the transgene with marker loci known to flank Sl was consistent with a map position close to Sl. Genomic sequences that are adjacent to the transgene insertion site were cloned and found to be tightly linked with the Sl locus in interspecific crosses using nontransgenic mice. Recombination analysis utilizing the transgene insertion site locus was used to show that a recently identified hematopoietic growth factor is encoded at Sl. The cloned sequences from the transgene insertion site are polymorphic in inbred strains of mice and can be utilized to determine the genotype at Sl during early embryonic development. Further, they may be useful in characterizing the genomic region near Sl that is affected in Sl deletion mutants.