The BRG mouse was developed by Mamoru Ito of the Central Institute for Experimental Animals (CIEA) in Japan. The Rag2 mouse was developed in the laboratory of Frederick W. Alt at Columbia University. The Rag2 targeted mutation was created by targeting the Rag2 gene in CCE ES cells derived from the 129S6 strain. Targeted ES cells were injected into C57BL/6 or MF1 blastocysts. The Il2rg targeted mutation was developed by Dr. Kazuo Sugamura of Tohoku University by targeting the gene in El4-1 or CCE ES cells derived from a 129 strain. Targeted ES cells were injected into C57BL/6 blastocysts. CIEA received the mouse as a non-inbred strain. The Rag2 mutation was backcrossed at CIEA to BALB/cA for at least 8 generations to generate BALB/cA-Rag2tm1Fwa. The mouse carrying Il2rgtm1Sug on a non-inbred strain background was then backcrossed to BALB/cA-Rag2tm1Fwa for eight generations to generate the BRG mouse. Taconic received stock in 2011, and the line was derived through embryo transfer. The mice are maintained by breeding females homozygous for both the Rag2 and Il2rg mutant alleles with males that are homozygous for the Rag2 allele and hemizygous for the Il2rg mutant allele.
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