Rederivation is used to establish specific pathogen-free (SPF) mice. To do this, Core personnel transfer preimplantation embryos into SPF pseudopregnant recipient females.
The efficiency of the rederivation procedure depends on the strain of mouse. Inbred strains require larger starting numbers of mice for a reasonable chance of success.
Rederivation includes comprehensive health monitoring (e.g., serology, bacteriology, parasitology and pathology) to confirm the success of the rederivation procedure. Once the results are obtained, they will be sent to the veterinarian of the receiving facility to obtain approval for shipment. The entire process, from rederivation to shipment of animals, takes 10 to 12 weeks (depending on when health results are obtained). For pricing, please contact Audra Guikema.
This method is a faster alternative to traditional rederivation and can be done with one or two males carrying the gene of interest. Sperm cryopreservation to rederivation is an option for non-fixed lines.
Investigators interested in the mouse sperm cryopreservation to rederivation service should have two fertile males, two to six months of age. The service begins once VARI receives a completed request form via iLab and the male mice. The males are housed individually for a week before the service begins.
Sperm is isolated from the cauda epididymis and vas deferens of the male mice and placed into warmed cryoprotective media supplemented with an antioxidant. Sperm is allowed to “swim-out” for 10 minutes, and then four, 1 mL aliquots are aspirated into each straw. Approximately 20 straws are used. Each straw is heat sealed and placed into a cassette (five straws/cassette). Loaded cassettes are statically frozen in liquid nitrogen vapor for 10 minutes, then plunged into liquid nitrogen and moved to two different liquid nitrogen tanks for long-term storage. Offsite triple banking is available for an additional cost.
One to two previously frozen straws will be thawed. In vitro fertilization will be performed with the thawed sperm and strain-specific oocytes. The following day, two-cell stage embryos will be collected, media washed 10 times, and implanted into pseudopregnant foster mothers.
The Vivarium and Transgenics Core requires five or more superovulated, plugged females to conduct rederivation services. To obtain these numbers, a comparable number of individually housed stud males (five or more) also are needed. If only a couple males or breeder pairs can be obtained, Core personnel will breed the animals until there are a sufficient number of animals (this will be an additional per diem and technician time cost).
This service is primarily used for lines that are fixed and need to be maintained as homozygous lines.