The new strain is available as live mice

Bringing the mice into Oxford

1. Obtain the contact details of the facility manager in the exporting facility and submit this with details of the strain and the number of animals required to the local BMS technical manager at the importing facility (i.e. FGF, JR-BMSU or BSB).
2. The technical manger will obtain an up-to-date health certificate for the mouse line and request and coordinate any further tests that might be deemed necessary prior to the import.
3. A decision will be made concerning the necessity for rederivation and where the mice can be housed prior to rederivation.
   • If the health status and screening certification is not compatible with the local facility (i.e. FGF, JR-BMSU or BSB), there are two potential options
   • The animals cannot be held at Oxford University and the rederivation must proceed via a commercial service facility, e.g. Harlan UK, Charles River. BMS have negotiated fees for these services and they can be organized via the local technical manager
4. The animals can be held at a Quarantine facility within the Science Area. It is within this area that embryos will be generated for the rederivation service.
5. The BMS technical manager or import team will apply on your behalf for an import license for the receipt of live mice from DEFRA
6. The BMS technical manager or import team will coordinate the arrival of the live mice from the exporting facility

Initiating the rederivation project

1. Complete a Rederivation service request form. The form represents a service agreement, outlining the terms and conditions of the service and defines the details of project cost. This needs to be signed by the principal investigator prior to commencement of work.
2. Complete the technical information sheet at the end of the Rederivation service request form which provides the details of the strain
3. Raise a Purchase Order for the total project cost and add this information to the technical information sheet.
4. Send the completed form to the following email address: transgenics@well.ox.ac.uk

Deciding on an appropriate breeding scheme for the production of embryos

We would recommend the use of genetically modified stud males of the particular strain to be imported and the use of wild-type females which can be brought in via commercial suppliers on demand. Embryo donors are typically superovulated as part of the embryo harvest procedure and the efficiency of this superovulation process depends critically upon the strain and the age of the females. The use of wild-type females bought at an appropriate age maximizes the success of the rederivation project by maximizing the embryos yield.

Use of genetically modified females, e.g. for rederiving homozygous lines or lines with multiple transgenes.

Homozygous lines or lines which harbor multiple transgenes or modified loci can be rederived through the use of appropriately aged genetically modified females which will be mated with genetically modified studs. The superovulation process works efficiently with immature mice and subsequently breeding boxes to generate the required females will be needed. If the efficiency of embryo production is low (which is frequently the case with genetically modified in-bred females), the rederivation process may require several sessions which thus require several experimental groups of appropriately aged females.

For single locus homozygous strains, it is recommended to use these studs with wild-type females to obtain heterozygous embryos and to breed back to homozygosity once the strain is rederived.

Where genetically modified females are to be used, it is essential to discuss this matter with the Wellcome Trust Centre for Human Genetics Transgenic Core prior to project commencement.

Minimum numbers of animals required to commence a rederivation experiment

Although a derivation is theoretically possible to achieve using a single female and a single male mouse, the procedural and technical overhead that the rederivation service demands have led us to impose requirements on animal numbers. If insufficient mice are available, a rederivation project will not proceed and the mice must first be bred a generation within the Quarantine Facility in order to obtain the necessary numbers of animals required.

Where wild-type females are used as embryo donors:

• 4 stud males of appropriate genotype and of breeding age
• Wild-type females required for the project will be purchased directly by BMS and the costs are included in the project cost

Where genetically modified females are used as embryo donors (e.g. homoyzgous or lines harbouring mutliple transgenes)

• 4 stud males of appropriate genotype and of breeding age
• At least 2 groups of at least 4 immature (3-4) week old females which will frequently need to be bred in the quarantine facility. The costs involved in breeding these mice are not included in the project cost and will be recharged to the group in the monthly cage cost bill

The rederivation can commence

1. The import team will arrange for the mice to be housed appropriately within the Science Area Quarantine Facility and will set-up breeding boxes, as required. Frequently, a back-up breeding pair will be set-up to generate new mice in case there is a fertility issue with the group of studs that were received
2. The import team will coordinate the rederivation process with the Wellcome Trust Centre for Human Genetics Transgenic Core Facility
3. Female mice will be superovulated and mated with the studs
4. Oviducts will be dissected from the culled females and sent to the Wellcome Trust Centre for Human Genetics Transgenic Core Facility
5. Embryos will be harvested, cultured overnight to the two-cell stage and implanted into foster mothers within our specific pathogen-free facility.
6. When pups are born, the mother will be health screened to assess the health status of the newly derived pups
7. Once the health certificate is obtained, the mice can then be distributed to the local holding facility with the University (i.e. FGF, JR-BMSU or BSB).