GENEAS now offers the ability to archive important mouse lines as embryos and/or sperm. Most lines can be cryopreserved as sperm though embryo freezing is required for lines that must be maintained as homozygous or on a specific genetic background. Sperm freezing requires fewer mice for freezing and is cheaper though revival of the line is more expensive than if embryos were frozen. Additionally, if shipping samples to collaborators, shipping embryos is often preferred to sperm as many facilities do not have the capability to perform IVFs.
For each male, we freeze 9 straws of semen, which can be used for 9 separate IVFs. We perform a QC (level 1) on the sperm sample and for an additional charge will perform further QC work at level 2 or level 3. Typically we freeze 3 or 4 males per line.
QC Levels for Sperm Cryopreservation
- QC Level 1 (default). Performed on all samples. Involves thawing one straw and observing level of sperm activity. There is no guarantee that the sperm sample is capable of successfully being used in an IVF though in the majority of cases this will be so. There is no confirmation that the sperm sample carries the correct genotype.
- QC Level 2. Confirms that the sperm sample is capable of generating viable embryos by performing an IVF and culturing embryos to the blastocysts stage. The blastocysts can be examined by PCR to confirm the genotype.
- QC Level 3. Confirms that the sperm sample is capable of generating viable pups by performing and transferring the embryos to a pseudopregnant recipient female. The pups born can be genotyped.
Cryopreservation of Embryos
For embryo cryopreservation we require 8-10 males of fertile age (8 weeks - 6 months) and if the line must be maintained as homozygous or on a particular background 30-50 female mice aged 21-28 days will be required. We would normally manage any breeding to produce the female mice. Two levels of cryopreservation are offered:
- Embryo Level 1. We will store a minimum of 200 embryos split between two repository tanks. This is normally sufficient to ensure the line is preserved for future use.
- Embryo Level 2. We will store between 400 and 500 embryos. This is for large scale projects where many embryos are required e.g. for shipping to external collaborators.
QC Levels for Embryo Cryopreservation
- QC Level 1 (default). 10-20 embryos are thawed and cultured to the blastocysts stage to confirm viability. The embryos re available to be genotyped if desired.
- QC Level 2. 10-20 embryos are thawed and transferred into a pseudopregnant recipient female. The pups born can be genotyped. In most cases this level of QC is not required as viable embryos in almost all cases go on to produce viable pups. It is mostly used for lines that are not available anywhere else in the world and the researcher needs added assurance that the line has been cryopreserved.
Cryopreservation of Embryos and Sperm
We feel this is the optimal way to archive a line when cost is an issue. It affords the possibility of having inexpensive semen samples stored from 2 males but also having 100 2-cell embryos cryopreserved. If for some reason, IVF is not available (or not successful) then there are always some embryos to reanimate the line. If a collaborator requires the line, they can be sent semen or embryos depending on what capabilities they have at the receiving institute. The cost of this service is midway between the cost of a full embryo cryopreservation service and the sperm freezing service.
IVF for reanimation of lines
We offer an IVF service for cryopreserved sperm.
How to Lodge a Request
Please discuss your requirements with the Cryopreservation Team (firstname.lastname@example.org) or the Facility Manager. For internal researchers, a formal request must be submitted electronically using the Emus system. For external researchers, we will assist in lodging the request on our system.