Here at the Mouse Biology Program (MBP), we have extensive experience with mouse breeding and colony management. Our trained professional staff can assist you with devising and implementing a breeding plan to generate the cohort or mouse model your research requires.
Mouse Colony Management
MBP Mouse colony management includes the following services.
- Setting up breeding pairs.
- Cage monitoring for pregnancies and newborn pups
- Record keeping of all essential data. Client colony data can be viewed live by access to colony data management system “MOSAIC”.
- Tail-cutting and ear-notching pups for genotyping as needed.
- Submission of mouse tissue for in-house genotyping or transfer to customer for testing.
- Weaning pups into holding cages.
- Communicating monthly colony reports to the customer.
- Monthly billing of UC account or customer PO for all vivarium and genotyping services.
All cages assigned to a particular client’s breeding project will be charged to the client’s account as a per diem (cost/cage/day). These include both breeding cages and cages of weaned pups.
When genotyping is necessary, pups will be ID'ed by toe-clipping (or ear-notching and tail-cutting). Pups will be identified by cage number, toe-clip (or ear-notch) number, and date of birth.
Mice imported from vendors like JAX, Harlan and CRL may be imported directly into our MBP conventional facility for custom breeding projects.
Mice imported from a customer’s own facility may require re-derivation by embryo transfer to enter the MBP conventional housing facility and will always require re-derivation to enter our SPF barrier housing. Descriptions of our MBP Clean Barrier (Conventional) housing and SPF barrier housing facilities can be found here Mouse Housing.
Germline Testing of Chimera
Chimera are produced when clonal mutant ES cells are injected into donor blastocysts (or morula) and resulting pups contain a mixture of both mutant and wild type (host blastocyst) cells.
At the MBP, chimera are assessed for coat color at 10 days of age. The % coat color that is mutant cell derived is thought to correlate with the probability that mutant cells contributed to the germline (testes) cells of the chimera. Therefore, all appropriately sexed chimera determined to contain 50% or more mutant cells will be set with females. Breeding will begin when males are 7 to 9 weeks of age. When possible, each male chimera will be set with up to two females of the appropriate genetic background for GLT breeding.
Most mouse Embryonic Stem (ES) cells lines are derived from male mice, this is the case for KOMP and Eucomm generated ES cells and the ES cells used by the MBP for targeting projects. Therefore, in most cases, only the male chimera are bred for Germ-Line Transmission testing (GLT).
Chimera are allowed to breed until either they produce the desired heterozygous germline pups, they are deemed nonproductive, or they produce 25 wild type pups, whichever comes first.
If a male chimera is non-productive for 30-45 days, the male will be submitted for sperm collection, sperm morphological analysis and determination of suitability for IVF services. Please note that some chimera are hermaphroditic and may not produce sperm at all.
We estimate a timeline of 4- 6 months for germ-line transmission testing.
Once founders are produced we will proceed with arranging shipment or any additional services requested such as FLP or Cre recombination breeding.
In Vivo Recombinase Breeding
In Vivo Recombinase Breeding
The MBP provides in vivo recombination breeding to remove Frt, Lox P and Rox cassettes and transgenes.
Typically, selection cassettes have a strong promoter for reliable in-vitro expression. This promoter can also cause undesirable down-stream expression and should be removed prior to phenotyping the mutant mice. Therefore, founder mice produced by gene targeting usually require in-vivo breeding to remove a Neo or Puro positive selection cassettes.
For example, in the construct illustrated below, the Abc allele is upstream of a Neo cassette that is flanked with Frt (flp recombinase targets) sites.
Exposure of the construct to Flpase removes the Neo cassette and its B-actin promoter, leaving only the Abc floxed allele.
Flp, Cre and Dre recombination breeding services by the MBP include the purchase and importation of the appropriate recombinase-expressing mouse, two rounds of breeding to ensure cassette removal and genotyping of offspring.
There are several Flp-recombinase expressing mice to choose from, several are distributed by the UC Davis MMRRC Repository and are congenic with the C57Bl/6N mouse strain normally produced by the MBP and KOMP Repository, see for example C57BL/6N-Tg(CAG-Flpo)1Afst/Mmucd from the MMRRC catalogue number 036512-UCD that is on the B6/N strain background.
Tissue-Specific Recombination Breeding
Please note that unless the Recombinase gene is in the germline, as is the case with global Cre mice, breeding to a tissue-specific mouse model will require reincorporation of the Cre gene at every generation.
The KOMP and EUCOMM generated knock-out first allele.
Below please see the construct diagram from a typical KOMP knock-out first allele that contains a Neo cassette and B-actin promoter. This example is an allele for gene Il33, KOMP project CSD88909.
From the schematic above, you can see that the allele is a knock-out by virtue of the pA upstream of the floxed exons (exon 5 through exon 7).
In order to generate the conditional allele, the trapping cassette (En2SA-IRES-LacZ-pA) and the Neo cassette and its human beta actin promoter (hbactP-Neo-pA) need to be removed. Fortunately, these two cassettes are flanked by two FRT sites and can be removed in-vivo by breeding to Flp-expressing mice. Once those segments are removed, the allele is fully conditional; the allele would contain exons 1, 2, 3 and 4 upstream of floxed exons 5 through 7.
Fees and timeline for Flp breeding of KOMP clones and Neo cassette removal.
In vivo Flp or Cre breeding of KOMP or Eucomm vector-generated mice includes wild type and recombinase-expressing mouse purchase, importation and two rounds of breeding to ensure the complete deletion of the particular cassette. We estimate a timeline of 4-5 months for such breeding projects.
Breeding to Generate Homozygous Mice
Heterozygous to Homozygous Mice
Mice produced from germline testing of chimera or pro-nuclear injection of transgenes or CRISPR/Cas9 gRNA are usually heterozygous (referred to as hemizyogus for transgenes). We highly recommend you build up and maintain a colony of heterozygous mice before attempting to generate the homozygous mice your project requires.
Further, founder pups generated using CRISPR/Cas9 gene editing may be bi-alleleic and therefore breeding to segregate the two alleles followed by breeding het to het would be needed.
Typical costs for a project starting with two breeding pairs of heterozygous mice will cost in the region 2-4K and take between 12 and 20 weeks to complete.
We recommend genotype confirming the first generation of hom x hom offspring to ensure the line produced is homozygous.
Cohort Generation and Colony Maintenance
Cohort Generation and Colony Maintenance
Experienced colony mangers will build and maintain your mouse colony in accordance with your experimental requirements. In addition to providing you with monthly colony reports, through MOSAIC you will have 24/7 access to information on your colony.
The size of your mouse colony will depend on your requirements. Cage costs and colony management fees can quickly add up. For simply maintaining a strain, 2-3 breeding cages and 6-8 holding cages is sufficient. This number of cages will cost between $300-$500 USD per month.
Cryopreservation of mutant strains is highly recommended for insurance against accidental loss, see MBP service rates.
Back-Crossing by Speed Congenic Breeding
Backcrossing by Speed Congenic Breeding
Single Nucleotide Polymorphisms (SNP) between different mouse strains can be utilized to shorten the number of generations of back-crossing required to achieve a true congenic strain. After each round of breeding, we sample the transgenic offspring via SNP analysis and determine which of them have the highest percentage of the desired (recipient) strain. We then make recommendations for which offspring to select for breeding in the next round. We recommend screening more animals in the earlier generations (N2/N3) and fewer in the later generations. For example, we recommend sampling 12 mutant mice at N2, ~10 at N3, ~8 at N4, ~6 at N5.
Sample Picture (from the Web)
Following the testing scheme above, a congenic line can be established by N5 (1.5 years) compared to traditional backcrossing that requires at least ten generations and approximately three years of breeding.
The current rate for SNP analysis can be veiwed here. You may send us your mouse samples for testing and we will provide you with our recommendations for which mice to use for the next generation of breeding. For backcrossing mice housed at MBP, we estimate a cost of $9,508 (paid by UC recharge account)/$13,730 (Non-Profit institutions) this includes all mouse housing, colony management, genotyping and SNP analysis for six generations , which is the usual number of generations required to establishing the congenic line. The actual fees may vary as this process is highly dependent on the number of mice tested and SNPs analyzed.
Custom Breeding Projects
Sample Stock picture, need to replace with our own.
The MPB has dedicated space, resources, and experienced colony mangers and vivarium staff to assist you with design and implementation of your project. We would be happy to discuss any of your mouse breeding requirements.
Due to the large number of factors affecting breeding performance, such as the specific mouse strain characteristics and the mutant phenotype, we cannot offer any guarantees in terms of output or numbers of cages required. However, we can offer general guidelines as to the number of cages and mice required for a particular project.
UC Davis M3 (Barrier Housing Facility)
The UC Davis, M3 Barrier is an 18-room, high health-status, restricted-entry mouse barrier facility. Entry is limited to animal care and transgenic core personnel only. Personnel enter through a shower facility; all equipment and supplies are sterilized prior to transfer into the facility. Staff wear personal protective equipment, including dedicated uniforms and shoes, hair bonnets, masks and gloves. Mice are housed in ventilated caging systems and manipulated under laminar change stations. All mice are rederived by embryo transfer into this facility. Dirty bedding sentinels are set up in each mouse room, with the exception of Maternity (Room 1, Room 11). Sentinels and pseudopregnant recipient females are supplied from a CD-1 breeding colony from this barrier (Room 5). Sentinels and random weanlings from the room are screened quarterly, with the exception of the maternity room where each recipient animal is sent for pathogen screening at the time of litter weaning.
A current health report from M3 Breeding (Room 2 , 8; and 15 are used for germ-line mating of mice created in the barrier facility and rooms 6 and 18 are used for holding of weaned animals and stock breeding of MMRRC live lines) can be found at the links below. Maternity (Room 1, Room 11) is used exclusively to house embryo transfer recipient dams, and does not have dirty bedding sentinels. Instead, each embryo recipient is screened upon weaning of their litter. A report will be provided once the recipients are screened. Health screening and report preparation takes about 2 weeks post weaning, and will be made available prior to shipment of the litter.
UC Davis MBP Vivarium (Conventional Housing)
The UC Davis Mouse Biology Program Vivarium is a 7-room, Clean Barrier facility. Entry is limited to animal care personnel only. Staff wear personal protective equipment, including dedicated uniforms, shoes and gloves. Mice are housed in ventilated caging systems and manipulated under laminar change stations. Mice are rederived into the facility by embryo transfer and subsequent breeding (Rooms 114, 110, 111, 112), obtained from commercial vendors (Rooms 109, 111), imported from a variety of institutions with varying health statuses (Room 116), or thoroughly health screened and imported from institutions with clean health status for phenotyping services (Room 115).
The importation room is physically separated from the main vivarium. Cross contamination is prevented by strict equipment and personnel traffic patterns, dedicated and separate personnel for importation and phenotyping housing, attention to room order and change of personal protective equipment. Dirty bedding sentinels are set up in each mouse room and are screened quarterly. Sentinels are obtained from the CD-1 breeding colony housed in the M3 barrier. In addition, each embryo recipient undergoes a rodent health screen at the time of weaning. Health screening and report preparation takes about 2 weeks post weaning, and will be made available prior to shipment of the litter.