Genetic analysis of mouse t haplotypes using mutations induced by ethylnitrosourea mutagenesis: the order of T and qk is inverted in t mutants.
The t region of mouse chromosome 17 exhibits recombination suppression with wild-type chromatin. However, the region has resisted classical genetic dissection because of a lack of defined variants. Mutations induced by N-ethyl-N-nitrosourea (ENU) at the Brachyury (T), quaking (qk), and tufted (tf) loci of the mouse tw5 haplotype have now allowed the analysis of crossovers between two complete t haplotypes. A classical breeding analysis of the complete t haplotypes, tw5 and t12, utilizing the newly induced markers, reveals two inversions in t chromatin: one involving T and qk, and one involving tf and the H-2 complex. Moreover, the recombination frequency between the loci of T and qk is reduced compared to the frequency reported in normal chromatin. These two inversions are a sufficient explanation for the recombination inhibition with normal chromatin exhibited by t haplotypes isolated from the wild. Furthermore, the reduced recombination frequency between T and qk may indicate that the proximal gene rearrangement is not a simple inversion.
Justice
M J
MJ
Division of Biology, Kansas State University, Manhattan 66506.
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V C
VC
D000818:Animals; D007446:Chromosome Inversion; D002874:Chromosome Mapping; D005038:Ethylnitrosourea / Q000633:toxicity*; D005804:Genes, Lethal; D006239:Haplotypes; D051379:Mice; D008815:Mice, Inbred Strains; D008821:Mice, Quaking; D009153:Mutagens; D009154:Mutation; D011995:Recombination, Genetic; D013489:Suppression, Genetic
D009153:Mutagens; D005038:Ethylnitrosourea