What is a "tool strain"?
Until a better answer shows up...

A tool strain appears to be a mouse strain that is useful for making recombinant mice.  It has genes inserted into its genome to make detection of your manipulations easier.  In this case several phenotypes (luciferase, human SMN) can be observed as well as a tetracenomycin resistance marker is in place so that offspring with the gene can be easily estimated.  


  These Tg(SMN2)89; Smn1+/-; Tg(SMNΔ7)4299; ROSA26rtTA; "old" Luci-TRE-SMN mice allow high levels of both luciferase and full-length human SMN expression to be regulated by the addition/removal of doxycycline. These may be useful as a fluorescent reporter and/or Tet-On/Tet-Off tool strain for doxycycline-inducible rescue of Type II (moderate) proximal spinal muscular atrophy (SMA).