B6(Cg)-Tyr^c-2J/J

Stock number: 000058
Strain synonyms: B6 albino, albino B6
Research areas: Dermatology Research, Mouse/Human Gene Homologs, Research Tools, Sensorineural Research

Description

B6(Cg)-Tyr^c-2J/J, or B6-albino mice, are C57BL/6J mice that carry a mutation in the tyrosinase gene. Pigment is completely absent from skin, hair and eyes in mice homozygous for Tyr^c-2J. This unique characteristic makes these mice ideal for creation of novel strains with targeted mutations (gene knockouts). B6-albino mice are used to generate blastocysts that can be used for microinjection of genetically modified C57BL/6J embryonic stem cells. Following implantation and gestation, resulting offspring that are chimeric for the donor embryonic stem cells and the recipient blastocyst are easily identified by coat color. This allows an easy method to create knockout mice on the C57BL/6J genetic background.

Detailed description

Mice homozygous for Tyr^c-2J are phenotypically identical to homozygotes for the classic albino allele. Pigment is completely absent from skin, hair and eyes. While Tyr mRNA levels of Tyr^c-2J homozygotes are similar to those of wild-type mice, there is virtually no tyrosinase protein present (Le Fur et al. 1996). Both homozygote and heterozygote mice are highly resistant to light damage and exhibit retinal degeneration (increased photoreceptor death) into young adulthood. Degeneration does not continue in adult mice (Bravo-Nuevo et al. 2004).

Development

Tyr^c-2J arose in 1970 at The Jackson Laboratory on a C57BL/6J congenic strain carrying Tyrp1^b (Chr 4) and Hps1^ep (Chr 19) when that congenic was at generation N20. Tyrp1^b and Hps1^ep were eliminated from the Tyr^c-2J line by further backcrossing to C57BL/6J (Lane 1973). It was subsequently indicated (Hughes et al., 2007) that the Tyr^c-2J mutation arose in C57BL/6J-derived sequence since Dale1 ES cells, which derived from this strain, were found to have C57BL/6J-derived sequence flanking the Tyr locus at D7Mit350 and D7Mit323.

Allele

Symbol: Tyr^c-2J
Name: albino 2 Jackson
MGI accession ID: MGI:1855985
Generation method: Spontaneous
Attributes: Null/Knockout
Marker symbol: Tyr
Marker name: tyrosinase
Chromosome: 7
Strain of origin: B6.Cg-Tyrp1^b Hps1^ep
Site of expression: Expressed in melanosomes
Molecular note: This mutation has a G-to-T base change at coding nucleotide 230 resulting in an amino acid change from arginine to leucine at residue 77 (p.R77L) which lies in the highly conserved DDRE sequence. Nucleotide 230 is at the alternative 5' splice donor site for exon 1 and this allele does not produce the 1a or 1b subset of tyrosinase transcripts but does produce a significant increase in 1c and 1d transcripts. Western blots of homozygous mutant skin extracts demostrate the nearly complete absence of the broad 76-84 kDa band of glycosylated wild-type tyrosinase. No tyrosinase activity was found in hairbulb extracts from homozygous mice.

Allele

Symbol: Cox7a2l^s
Name: short
MGI accession ID: MGI:6276120
Generation method: Not Applicable
Attributes: Not Specified
Marker symbol: Cox7a2l
Marker name: cytochrome c oxidase subunit 7A2 like
Chromosome: 17
Strain of origin: multiple strains
Molecular note: This allele contains a 6 bp microdeletion causing the loss of two amino acids and truncating the protein to 111 amino acids instead of 113 amino acids. It is found in BALB/cAnCrl, BALB/cJ, C57BL/6Cr, C57BL/6JCrl, C57BL/6JOlaHsd, C57BL/6NCrl, C57BL/6NJcl, C57BL/6NHsd, C57BL/6NTac, C57BL/6NJ, B6(CG)-Tyr/J, C57BL/6JClr, C57BL/6JArc, C57BL/6JJcl, C57BL/6JJmsSlc, C57BL/6JOla, C57BL/6JOlaHsd, C57BL/6JRcc, C57BL/6JRccHsd, C57BL/6JBom, and C57BL/6JBomTac mice.
General note: Querying the sequences of the Sanger Mouse Genomes Project reveals that the short allele with its 6 bp deletion exists in C57BL/6J, C57BL/10J, C57BL/6NJ, C58/J, BALB/cJ, C3H/HeH, 129S5/SvEvBrd, NZW/LacZ, and SEA/GnJ, but the long allele lacking the deletion exists in 129S1/SvImJ, A/J, AKR/J, BTBR T⁺ Itpr3^tf/J, BUB/BnJ, C3H/HeJ, C57BR/cdJ, C57L/J, CAST/EiJ, CBA/J, DBA/1J, DBA/2J, FVB/NJ, I/LnJ, KK/HiJ, LEWES/EiJ, LP/J, MOLF/EiJ, NOD/ShiLtJ, NZB/BlNJ, NZO/HlLtJ, PWK/PhJ, RF/J, SPRET/EiJ, ST/bJ, WSB/EiJ, ZALENDE/EiJ.