I'm trying to use this dataset to look at RNA expression levels in mice. The annotation for each read looks something like this chr1.10263 where the chromosome number is written then followed by a period and then followed by a random five digit number. I can't find anything about it online, and it isn't matching up with any of the Mus.musculus annotations in bioconductor, so I'm at a loss with what to do. If anyone can help, that'd be great. Thanks!