B6.Cg-Per2^tm1Brd Tyr^c-Brd/J

Stock number: 003819
Product name: mPer2^Brdm1
Research areas: Cell Biology Research, Dermatology Research, Endocrine Deficiency Research, Neurobiology Research

Description

Mice that are homozygous for the targeted mutation (Per2^tm1Brd) exhibit a shortened circadian period and a loss of persistent circadian rhythmicity when maintained in constant darkness. This mutant mouse strain may be useful in studies related to the regulation of the sleep-wake cycle.

Detailed description

Mice that are homozygous for the targeted mutation are viable, fertile, normal in size and do not display gross physical or behavioral abnormalities. A mutant transcript, if translated, would generate a protein with an 87 amino acid deletion. When maintained in constant darkness, two phenotypic components are exhibited: a shortened circadian period and a loss of persistent circadian rhythmicity. When housed under constant light, homozygotes exhibit normal activity rhythm but a period length of less than 24 hours. By 9-12 months of age, homozygous females exhibit low reproductive success and produce small litters when compared to wildtype. These mice also carry the recessive Tyr^c-Brd mutation that, when homozygous, results in albino coat color. This mutant mouse strain may be useful in studies related to the regulation of the sleep-wake cycle.

Development

A targeting vector containing neomycin resistance and herpes simplex virus thymidine kinase genes was used to disrupt two Per2 exons encoding half of the PAS B domain and the entire PAC subdomain. The construct was transfected into 129S7/SvEvBrd-Hprt^b-m2 derived AB2.2 embryonic stem (ES) cells. Correctly targeted ES cells were injected into C57BL/6-Tyr^c-Brd blastocysts. The resulting chimeric mice were bred with C57BL/6-Tyr^c-Brd mice (also called C57BL/6Brd-Tyr^c-Brd). The donating investigator reported that mutant mice were then backcrossed to C57BL/6-Tyr^c-Brd mice for at least five generations. Mice homozygous for both the Per2^tm1Brd targeted mutation on chromosome 1 and the the recessive Tyr^c-Brd mutation on chromosome 7 were sent to The Jackson Laboratory Repository (see SNP notes below).

A 32 SNP (single nucleotide polymorphism) panel analysis, with markers covering all 19 chromosomes and the X chromosome, was performed on the rederived living colony at The Jackson Laboratory Repository. This revealed 3 markers (one on chromosome 1 and two on chromosome 15) that were not fixed for C57BL/6 allele-type. The marker on chromosome 1 appears to be fixed as homozygous for 129 allele-type. This marker is close to the Per2 locus and is likely to be original ES cell genome segregating with the Per2^tm1Brd targeted mutation. The two markers on chromosome 15 (located at ~34 Mbp and ~58 Mbp) also appear to be fixed as homozygous for 129 allele-type. This may represent a large region of chromosome 15 that is fixed as homozygous for 129 allele-type.

Allele

Symbol: Tyr^c-Brd
Name: albino, Allan Bradley
MGI accession ID: MGI:3640303
Generation method: Spontaneous
Marker symbol: Tyr
Marker name: tyrosinase
Chromosome: 7
Strain of origin: C57BL/6
Site of expression: Melanocytes.
Molecular note: This mutation arose spontaneously in or around 1991 in the C57BL/6 colony of Dr. Alan Bradley. It has been used in linkage studies based on the location of the tyrosinase gene on Chr 7, and its phenotype is complemented by a tyrosinase mini-gene. Sequence analysis of exon 1 identified the same G-to-T transversion at coding nucleotide 230 (c.230G>T), resulting in replacement of arginine by leucine at amino acid position 77 (p.R77L), that is present in the albino 2 Jackson allele Tyr^c-2J. It reverts at a very low frequency (there were two incidences in the original colony between 1992 and 1995), resulting in black pups in otherwise albino litters.

Allele

Symbol: Per2^tm1Brd
Name: targeted mutation 1, Allan Bradley
MGI accession ID: MGI:1934020
Generation method: Targeted
Attributes: Null/Knockout
Marker symbol: Per2
Marker name: period circadian clock 2
Chromosome: 1
Strain of origin: 129S7/SvEvBrd-Hprt^b-m2
Molecular note: Two exons containing the most conserved region of the gene were replaced with PGK-neo cassette, resulting in the deletion of the PAC subdomain and half of the PAS B domain. RT-PCR and sequence analysis of mutant animals detected a mutant transcript with a predicted protein containing an 87 amino acid deletion.