Cryopreservation of mouse strains serves a number of important functions:

  • It provides reduction in number of mouse cages and in associated maintenance costs.
  • For strains difficult to replace, it provides insurance against disaster or pathogen outbreak.
  • Cryopreservation provides insurance against genetic drift.

Genetic drift is not trivial. Spontaneous mutations constantly arise in every mouse colony. Some of these mutations may spread throughout the colony until all mice are homozygous for them. These mutations may affect the phenotype of the line. However, cryopreservation can greatly reduce genetic drift’s impact.

Cryopreserve any mouse strain that is critical to your research that either you created yourself, or that may be difficult to reacquire. If a breeding error, genetic drift, loss of phenotype, or a pathogen outbreak hits your colony, and you have the strain cryopreserved, you can recover the original strain and continue your studies with minimal loss of time.

The cryopreservation service preserves mouse lines by sperm freezing.

At least 20 straws of sperm from three male mice are stored in two separate locations (note; males are sacrificed for sperm collection). Quality control of frozen sperm is assessed by thawing one straw of frozen sperm for IVF, with wild-type oocytes. The resulting embryos are transferred to pseudopregnant females to ensure they produce viable offspring, at least till E14.5. Embryo tissue samples are provided to the client for PCR verification of the strain.

Procedure

In order to preserve a line, the following is required:

  • At least 4 males of breeding age (3-8 months) of proven fertility
  • An Internal Service Order
  • Clients not from the Weizmann Institute should contact Rebecca Haffner.
  • All work done by the microinjection lab requires an IACUC code (Institutional Animal Care and Use Committee)  For Instructions
  • Once you have received an IACUC code a request must be made in Internal Services >Transgenic and Embryo Manipulation Lab. Fill in all fields. *Item select  #5 Cryopreservation of Mouse Strain.  Fill in all fields.
  • Note: The strain name entered on the order form will be the name used on the straw labels (maximum 16 characters).
  • Each strain to be frozen requires a separate order.
  • Contact Golda Damari (3221) with details of your order.

Important: When transferring the cages of male mice for freezing, the order number must be clearly written on the cage label.

In the case of complicated genotypes (> one mutation), or if there is strain information we should be aware of, please contact Dr. Rebecca Haffner before initiating the order.

In some rare cases, embryo cryopreservation may be necessary.

In the event of a waiting list for freezing, we appreciate your patience and cooperation.