The technique is valuable in providing a backup for unique or vulnerable genetically modified lines.
Cryopreservation also provides security against genetic drift, human error, natural disasters and loss of genes of interest. Preserved lines are readily available for transport and can allow for future rapid expansion of colonies when reanimated.
Validation demonstrates that the line has been successfully frozen and can be recovered. Samples can be validated using several methods:
No validation – sperm is thawed and motility assessed (NOTE: This does not guarantee that the sperm are able to fertilise an oocyte)
Basic validation – recovery and successful culture of embryos to two days
Full validation – recovery and production of live pups
The embryos and sperm are stored at two separate locations providing additional security.
Sperm freezing requires only 4 males and can be completed within 4 – 6 weeks depending on the method of validation used.
Embryo freezing is preferred for lines that must be kept as homozygous or lines on a mixed background. The number of animals needed and time taken to produce a target of 400 frozen embryos depends on how well the animals breed, the quality of embryos produced, and the validation method used.
In 2020 ABR further refined the embryo freezing process leading to a reduction in the number of mice required and a shorter completion time. The initial requirements are now for 3 males and 20 females. More females may be required if the females ovulate poorly, or the fertility rate is low. Depending on the availability of females, the service will take approximately 12-20 weeks.
Note: Breeding and housing prior to freezing is not included in the cryopreservation costs. When a line is breeding poorly and/or produces poor quality embryos an alternative target for freezing may require negotiation. ABR technicians will contact clients within approximately 12 weeks to discuss continuation of the process.
Mouse strains can be recovered from imported frozen embryos or sperm.
For more information please refer to the Frequently Asked Questions section on Cryopreservation. For assistance please contact firstname.lastname@example.org. To initiate freezing please complete the relevant Cryopreservation service order in the Services section of StuartWeb.