PT  - JOURNAL ARTICLE
AU  - Stefano Lazzarano
AU  - Marek Kučka
AU  - João P. L. Castro
AU  - Ronald Naumann
AU  - Paloma Medina
AU  - Michael N. C. Fletcher
AU  - Rebecka Wombacher
AU  - Joost Gribnau
AU  - Tino Hochepied
AU  - Claude Libert
AU  - Yingguang Frank Chan
TI  - Genetic mapping of species differences via “<em>in vitro</em> crosses” in mouse embryonic stem cells
AID  - 10.1101/148486
DP  - 2017 Jan 01
TA  - bioRxiv
PG  - 148486
4099  - http://biorxiv.org/content/early/2017/06/10/148486.short
4100  - http://biorxiv.org/content/early/2017/06/10/148486.full
AB  - Discovering the genetic changes underlying species differences is a central goal in evolutionary genetics. However, hybrid crosses between species in mammals often suffer from hybrid sterility, greatly complicating genetic dissection of trait variation. Here we describe a simple, robust and transgene-free technique to make “in vitro crosses” in hybrid mouse embryonic stem cells by inducing random mitotic crossovers with the drug ML216, which inhibits Bloom syndrome (BLM). Starting with an interspecific hybrid (between Mus musculus and Mus spretus) embryonic stem cell line spanning 1.5 million years of divergence, we demonstrate the feasibility of mapping enzymatic differences across species within weeks and the possibility of re-deriving whole mice. Our work shows how in vitro crosses can overcome major bottlenecks like hybrid sterility in traditional mouse breeding to address fundamental questions in evolutionary biology.Impact Statement By mixing hybrid mouse genomes in stem cells via mitotic recombination, genetic mapping and hybrid mosaic mice can be achieved in weeks, even across species barriers.