A male rat "SRR-Rocket Science" was introduced from American fancy rat colony (Spoiled Ratten Rattery: SRR, in Kansas City, Missouri) to Kyoto University on July 13, 2005. Inbreeding started from F1 progeny of male "SRR-Rocket Science" and a female PVG/Seac. Homozygous rats for grey mutation were selected for inbreeding.
Maintained by crossing of heterozygous and wild-type for Pearl mutation. This strain is heterozygous for Pearl (segregating strain) and homozygous for grey. Good breeding performance.