Black 6N


C57BL/6NTac Background

Nomenclature: C57BL/6NTac

  • The most widely used inbred as the genetic background for transgenic and mutant mice
  • Popular in research applications of addiction, oncology, immunology, metabolic disease and toxicology
  • B6NTac is the preferred model for diet induced obesity studies
  • B6NTac is reported to yield a higher number of embryos per superovulated female and males are known to have higher sperm fertilization rates
  • B6NTac is an excellent choice for the chronic experimental immune encephalomyelitis model of multiple sclerosis

Origin:  C57BL/6 litters were received in 1991 at F151 from the NIH Animal Genetic Resource. Cesarean derived in 1991 at Taconic, a foundation colony is maintained in gnotobiotic isolators. Origin is as follows: to NIH in 1951 from Jax at F32; to Jax in 1948 from Hall.



  • Strain Profile: Acy1f, Aladb, Car2a, Cas1g, Cd5b, Cd72b, Cd8ab, Cd8b1b, Ce2a, Es1a, Es3a, Esda, Ggc1b, Gpi1b, Gus-sb, H6pd1b, Hbaa, Hbbs, Hc1, Idh1a, Mod1b, Mup1b, Pep3a, Pgm1a, Trfb
  • Immunology: H2b, Ptprcb, Thy1b, H2-T18b
  • Retinal Degeneration: Crb1Rd8

Coat Color Loci: a/a, B/B, C/C

Color: Black

Species: Mouse

Animal Diet: NIH #31M Rodent Diet

Additional Info: View all B6 related publications

InVivos’ Health Reports can be found here.

C57BL/6NTac substrains carry the Crb1Rd8 mutation.Retinal degeneration 8, is a mild form of retinal degeneration that affects vision. This recessive mutation is a single base pair mutation in the Crb1 gene, Crb1Rd8 (Mehalow et al. 2003) The onset of the phenotype appears to be between 2 and 6 weeks of age (Pritchett-Corning, 2012).

C57BL/6J mice present a deletion (~17 Kbp) in the Nicotinamide Nucleotide Transhydrogenase (Nnt) gene. Nnt is a transmembrane protein that catalyzes the inter conversion of NADH and NADPH in the mitochondria. Studies suggest that the presence of Nnt is essential for mitochondrial defense against oxidative stress and for normal cellular metabolism (Huang et al. 2006). Taconic’s C57BL mice, including C57BL/6JBomTac, C57BL/6NTac and C57BL/10SgSnAiTac, or our B6D2F1 and B6129F1, do not carry the Nnt mutation which is present in C57BL/6J sub-strain.

Average litter size: 6-8
Average litter size: 6.2
Mean # litters/female: 7
Mean age breeder retired: 10 months
Mean # days to litter: 22