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 mink were selected for inbreeding.