An interstitial telomere array proximal to the distal telomere of mouse chromosome 13

Lambda clones of mouse DNA from BALB/c and C57BL/10, each containing an array of telomere hexamers, were localized by FISH to a region close to the telomere of Chr 13. Amplification of mouse genomic DNA with primers flanking SSRs within the cloned DNA showed several alleles, which were used to type eight sets of RI strains. The two lambda clones contained allelic versions of the interstitial telomere array, Telrs4, which is 495 bp in C57BL/10 and which includes a variety of sequence changes from the consensus telomere hexamer. Comparison of the segregation of the amplification products of the SSRs with the segregation of other loci in an interspecies backcross (C57BL/6JEi x SPRET/Ei) F₁ x SPRET/Ei shows recombination suppression, possibly associated with ribosomal DNA sequences present on distal Chr 13 in Mus spretus, when compared with recombination in an interstrain backcross, (C57BL/ 6J x DBA/J) F₁ x C57BL/6J, and with the MIT F₂ intercross. Analysis of recombination in females using a second interstrain backcross, (ICR/Ha x C57BL/6Ha) F₁ x C57BL/6Ha, also indicates recombination suppression when compared with recombination in males of the same strains, using backcross C57BL/6Ha x (ICR/Ha x C57BL/6Ha) F₁ Thus, more than one cause may contribute to recombination suppression in this region. The combined order of the loci typed was D13Mit37-D13Mit30-D13Mitl48-(D13Rpl, 2, 3, 4, Tel-rs4)-D13Mit53-D13Mitl96-D13Mit77-(D13MU78, 35). Data from crosses where apparently normal frequencies of recombination occur suggest that the telomere array is about 6 map units proximal to the most distal loci on Chr 13. This distance is consistent with evidence from markers identified in two YAC clones obtained from the region.