B6N.Cg-Meioc^tm1Dcp/J

Stock number: 031053
Product name: Meioc 3L
Research areas: Research Tools

Description

Meioc 3L (3lox) conditional mutant mice carry a FRT-flanked lacZ/neomycin cassette in intron 2 that disrupts expression of the mouse Meioc gene. Exon 3 is flanked by loxP sites, and can be adapted as an additional conditional allele. Both male and female homozygous 3L mice are infertile as germ cells fail to complete meiotic prophase and ultimately apoptose.

Detailed description

Meioc (meiosis specific with coiled-coil domain) is expressed in germ cells of both males and females during meiotic prophase and ultimately apoptose.

An FRT-flanked lacZ/neomycin insertion in intron 2 disrupts expression of mouse Meioc in this conditional targeted mutation strain (Meioc 3L; 3lox). Both male and female homozygous knockout mice are infertile as germ cells fail to complete meiotic prophase. Mouse germ cells lacking Meioc initiate meiosis: they undergo pre-meiotic DNA replication, they express proteins involved in synapsis and recombination, and a subset of cells progress as far as the zygotene stage of prophase I. However, cells in early meiotic prophase - as early as the preleptotene stage - proceed to condense their chromosomes and assemble a spindle, as if having progressed to metaphase.

MEIOC protein expression is not detectable by immunohistochemistry in adult testes or fetal ovaries of homozygous Meioc 3lox mutant mice.

Functionality of a lacZ reporter, contained in the 3lox targeting vector, has not been confirmed. It is anticipated that it will enable labeling of cells that would normally express Meioc.

Crosses to ACTB:FLPe mice (see Stock No. 005703) to excise the disruptive lacz/neomycin cassette create a functional Meioc gene with a conditional allele carrying 2 loxP sites (2lox or 2L) flanking exon 3. Although levels of Meioc expression have not been measured in the 2lox strain, expression is sufficient to reinstate fertility of homozygotes.

Cre-mediated recombination excision of exon 3 of the gene is predicted to result in a frame shift and generate a premature stop codon subsequent to exon 2 (e.g. Stock No. 031054).

Development

This strain was constructed using Knockout Mouse Project (KOMP) vector PG00048_X_6_E03 (Project ID: CSD25307). In brief, a cassette encoding the following was introduced to intron 2 of the mouse Meioc gene: FRT-SA-lacZ-pA-loxP-neomycin-pA-FRT-loxP. A third loxP site was placed in intron 3. The mutation was created via homologous recombination in (C57BL/6 x 129S4/SvJae)F1-derived v6.5 embryonic stem (ES) cells. This strain was backcrossed to C57BL/6NTac for more than 10 generations by the donating laboratory.

Allele

Symbol: Meioc^tm1Dcp
Name: targeted mutation 1, David C Page
MGI accession ID: MGI:5910924
Generation method: Targeted
Attributes: Conditional ready (e.g. floxed); Reporter; Null/Knockout
Marker symbol: Meioc
Marker name: meiosis specific with coiled-coil domain
Chromosome: 11
Strain of origin: (C57BL/6 x 129S4/SvJae)F1
Expressed genes: lacZ,beta-galactosidase,E. coli
Site of expression: Functionality of a lacZ reporter, contained in the 3lox targeting vector, has not been confirmed. It is anticipated that it will enable labeling of germ cells that would normally express Meioc.
Molecular note: The L1L2_Bact_P cassette was inserted at position 102667864 of Chromosome 11 upstream of exon 3 (Build GRCm38). The cassette is composed of an FRT site followed by lacZ sequence and a loxP site. This first loxP site is followed by neomycin resistance gene under the control of the human beta-actin promoter, SV40 polyA, a second FRT site and a second loxP site. A third loxP site is inserted downstream of exon 3 at position 102668692. The critical exon is thus flanked by loxP sites.