B6N mouse, Black 6N, C57BL/6NJ

Nomenclature: C57BL/6NJ

Type: Inbred

Important Note: This strain is homozygous for Crb1^rd8, the retinal degeneration 8 mutation. Photoreceptor degeneration is observed in spots, caused by retinal folds and pseudorosettes, found in the fundus of the eye.

Origin: In 1951 C57BL/6J, then at generation F32, were sent from The Jackson Laboratory to The National Institute of Health where they were maintained via sibling mating for decades. In 1980 this subline reached F126 and in 1984 embryos were cryopreserved at the NIH cryopreservation facility. In approximately 1994 some of these embryos were thawed and maintained via sibling mating and this subline was referred to as B6(e84) to specify that it derived from the embryos frozen in 1984. In September and October of 1997 a new set of embryos were cryopreserved from this thawed line by backcrossing +F6 females to their +F5 fathers. In 2005 some of these embryos frozen in 1997 were sent to The Jackson Laboratory where they were thawed and gave rise to C57BL/6NJ. Thus, C57BL/6NJ is devoid of mutations that may have arisen in any C57BL/6N sublines that remained on the shelf after the 1984 freeze. The embryos received by The Jackson Laboratory were thawed, the colony expanded, and re-frozen immediately. This strain is maintained with frequent replenishment from this frozen stock in order to arrest genetic drift.

Detailed description:  This is an NIH subline of C57BL/6. It was separated from C57BL/6J in 1951. 5 SNP differences have been identified that distinguish C57BL/6J from C57BL/6ByJ and C57BL/6NJ. Both C57BL/6ByJ and C57BL/6NJ type as follows: 08-015199792-M (rs3709624) is C; 11-004367508-M (rs3659787) is A; 13-041017317-M (rs3722313) is C; 15-057561875-M (rs3702158) is G; 19-049914266-M (rs3724876) is T. C57BL/6J types as follows: 08-015199792-M is T; 11-004367508-M is G; 13-041017317-M is T; 15-057561875-M is A; 19-049914266-M is G (Petkov and Wiles 2005.) This strain does not have the deletion in the Nnt gene that has been found in the C57BL/6J strain (Stock No. 000664). C57BL/6NJ mice are homozygous for Cyfip2^M1N, a spontaneous mutation in the cytoplasmic FMR1 interacting protein 2 that results in an amino acid substitution of phenylalanine for serine at position 968 (S968F). The mutation is found in all C57BL/6N substrains but is not present in the C57BL/6J strain or substrains. The mutation results in 45% lower acute response to cocaine as measured by locomotor hyperactivity (Kumar et al., 2013). This strain is also homozygous for the Del(13)1N deletion, common to the NIH sublines, which includes Zfp998 and Zfp997 and has been found to cause the loss of transcriptional repression of non-ecotropic endogenous retroviruses in C57BL/6NJ compared with C57BL/6J, which does not have this deletion (Treger et al., 2019).

JAX™ Stock No: 005304

More information about the strain - visit JAX website.

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