The Ms475 probe detects 2000 copies in Mus spretus. There are now 7600 bp of sequence of elements from the terminal burst. In this collection, there is only 1 private base substitution and 1 reversion. The probability of the reversion not being a recombinant or gene conversion is neglibable. This degree of divergence would be consistent with a date of the burst of about 15,000 yrs. ago.
Alternatively to the indicated arrangement, one could equally well assign the 6889 C in EL8 to be the revertant. Then EL8 and SK9 would exchange positions and substitutions 6981 and 6889 would exchange positions.
One of these sequence, EL111, was found in C57BL after an apparently natural gene transfer; and one, PL3, was used to follow a transfer by artifical breeding. Additional identical sequences have been obtained from Spret/Ei so that the definition of the lineage can be based completely on authentic spretus sequences. The sequence is defined from 5887..end. The promoter type is unknown.
The 22 bp deletion at 7285 is shared by SC3,4,7. It is not shared by PL2, and L1C105. This deletion takes out a chunk of the G-rich block in the 3' UTR. SC3,4,7 where all recovered by a PCR procedure that is biased against recovery of the G-rich block, and so the 7285 deletion may be a PCR artefact, or at least SC3,4,7 are a highly biased sample. The SK clones do not cover this position.
See Casavant & Hardies, 1994 for the original analysis of timing of these splits. We have since adopted a 1%/Myr pseudogene divergence rate instead of the 0.5%/Myr rate used in that paper, so the times should be proportionately reduced. Additional data in the Ms475 burst drive that time down further to 15 Kya as indicated above. Additional data in the Ms7024 burst brings the total divergence to 7/6400bp or 110 Kya. The best estimate of the Ms475/Ms7024 split is still about 0.2 Mya.