Figure 5. Disruption of Rubie by an SWR-specific endogenous retrovirus.

(A) Long-range PCR spanning a previously-mapped 27 bp region of Rubie intron 1 (shown in Figure S2) yielded the expected 300 bp product in B10, while a larger product of approximately 6 Kb was generated in SWR mice and CSS-14 mice with the Chr14^SWR/SWR genotype. Sequence analysis of this larger product revealed insertion of a 5542 bp endogenous retrovirus in the SWR allele. All other inbred strains produced the shorter PCR product, indicating that this insertion is unique to SWR. (B) The B10 and SWR alleles of Rubie are depicted schematically. (C) Rubie expression in the inner ears of B10, SWR, and CSS-14 mice at P6 was assessed in cDNA using PCR primers spanning exons 1 and 2 of Rubie. Rubie expression was observed in B10 and Chr14^B10/SWR mice, but not in SWR or Chr14^SWR/SWR mice. (D) Hemi-nested PCR using forward primers in exon 1 of Rubie and a reverse primer in the ERV demonstrated that aberrant splicing to the ERV occurs in both SWR inbreds and CSS-14 mice.