Sci. Aging Knowl. Environ., 4 February 2004
Vol. 2004, Issue 5, p. as2
[DOI: 10.1126/sageke.2004.5.as2]


CB6F1 Mouse

James M. Harper

The author is in the Department of Pathology and Institute of Gerontology, University of Michigan, Ann Arbor, MI 48109, USA. E-mail: jmharper{at}

Key Words: CB6F1 hybrid mouse • inbred mouse strain • Leishmania major infection

Abstract: This document contains a summary of the biological characteristics of the CB6F1 mouse, which is a first-generation hybrid strain produced by crossing BALB/c females and C57BL/6 males.

Strain CB6F1. This is a first-generation (F1) hybrid strain produced by crossing BALB/c females and C57BL/6 males.
Species and taxonomy House mouse, Mus musculus. Order Rodentia; Family Muridae (Old World rats and mice).
Source This strain is widely available from a number of commercial sources, including the National Institute on Aging (NIA). As a result of genetic contamination in the breeding colony of one of the parent strains, C57BL/6, at commercial supplier Harlan Sprague Dawley (see "Spoiled Stores"), new orders for aged mice (unaffected by the genetic contamination) from the NIA are presently limited to NIA grantees. The NIA predicts that the colony of aged CB6F1 mice will be restored sometime in 2004. For more information, go to or contact NadonN{at}
Phenotype Coat color is agouti.
History and genetic background Parental BALB/c mice were derived from original stock acquired in 1913; this strain is now widely distributed and has several substrains. The other parental strain, C57BL, was derived from original stock acquired in 1921 and is probably the most widely used of all inbred strains. C57BL also has numerous substrains, including BL/6. For additional information on strain history, see Festing, 1998.

General comments. CB6F1 is a general-purpose hybrid mouse strain. Overall, these mice perform well in cognitive tasks associated with spatial learning (Roullet and Lassalle, 1995). The strain is used especially for studies of reproductive biology and carcinogenesis. It is also a common source of zygotes for DNA microinjection. Recently, the human c-Ha-ras gene was inserted into this strain to create the CB6F1-TgHras2 mouse, a strain that serves as a rapid carcinogenicity testing system (Yamamoto et al., 1998).

The BALB/c genome includes the M. musculus-type Y chromosome, whereas the C57BL genome includes a Y chromosome of Asian M. musculus origin as well as a LINE-1 transposable element derived from the European mouse species M. spretus. The pseudoautosomal regions of the X and Y chromosomes have a characteristic Pst I pattern of restriction fragment sizes that is present only in the C57BL family of inbred mouse strains.

Caveats for researchers in the field of aging. Chromosomal aberrations have been shown to increase up to sixfold in 8- versus 40-month old CB6F1 mice (Martin et al., 1985). In addition, CB6F1 mice are highly susceptible to ultraviolet-induced immunosuppression and carcinogenesis (Noonan et al., 2003).

CB6F1 mice exhibit intermediate susceptibility to Leishmania major infection as compared with the parental strains (the BALB/c strain is highly susceptible, whereas the C57BL/6 strain is more resistant). This resistance is associated with the induction of nitric oxide (NO) production (Li et al., 1999); it should be noted that NO production declines significantly with age in all three strains of mice (Kissin et al., 1997).

Reproductive performance also declines markedly with age in CB6F1 males (Craigen and Bronson, 1982). Significant alterations occur during aging in the testicular androgen biosynthetic pathways in these males as well (Chubb and Desjardins, 1984).


Nothing available.

Pathologies of Aging. Little or nothing is known about common pathologies of aging in this strain.

February 4, 2004
  1. C. Chubb, C. Desjardins, Testicular function and sexual activity in senescent mice. Am J. Physiol. 247, E569-E573 (1984).
  2. W. Craigen, F. H. Bronson, Deterioration of the capacity for sexual arousal in aged male mice. Biol. Reprod. 26, 869-874 (1982).[Abstract]
  3. M. F. W. Festing, Inbred strains of rats and their characteristics. Mouse Genome Informatics, The Jackson Laboratory (1998) (
  4. E. Kissin, M. Tomasi, N. McCartney-Francis, C. L. Gibbs, P. D. Smith, Age-related decline in murine macrophage production of nitric oxide. J. Infect. Dis. 175, 1004-1007 (1997).[Abstract/Free Full Text]
  5. J. Li, C. A. Hunter, J. P. Farrell, Anti-TGF-beta treatment promotes rapid healing of Leishmania major infection in mice by enhancing in vivo nitric oxide production. J. Immunol. 162, 974-979 (1999).[Abstract/Free Full Text]
  6. G. M. Martin, A. C. Smith, D. J. Ketterer, C. E. Ogburn, C. M. Disteche, Increased chromosomal aberrations in first metaphases of cells isolated from the kidneys of aged mice. Isr. J. Med. Sci. 21, 296-301 (1985).[Medline]
  7. F. P. Noonan, H. K. Muller, T. R. Fears, D. F. Kusewitt, T. M. Johnson, E. C. De Fabo, Mice with genetically determined high susceptibility to ultraviolet (UV)-induced immunosuppression show enhanced UV carcinogenesis. J. Invest. Dermatol. 121, 1175-1181 (2003).[CrossRef][Medline]
  8. P. Roullet, J. M. Lassalle, Radial maze learning using exclusively distant visual cues reveals learners and nonlearners among inbred mouse strains. Physiol. Behav. 58, 1189-1195 (1995).[CrossRef][Medline]
  9. S. Yamamoto, K. Urano, H. Koizumi, S. Wakana, K. Hioki, K. Mitsumori, Y.� Kurokawa, Y. Hayashi, T. Nomura, Validation of transgenic mice carrying the human prototype c-Ha-ras gene as a bioassay model for rapid carcinogenicity testing. Environ. Health Perspect.106 Suppl. 1, 57-69 (1998).
Citation: J. M. Harper, CB6F1 Mouse. Sci. Aging Knowl. Environ. 2004 (5), as2 (2004).

Science of Aging Knowledge Environment. ISSN 1539-6150