Transgenic and Cryopreservation Unit
Urban Deutsch Head
Albert Witt Microinjectionist
Svetlozar Tsonev Animal caretaker
Pawel Styczynski Animal caretaker
Irina Geiger Animal caretaker
Katrin Bissegger Animal caretaker
We provide cryopreservation of mouse embryos and sperm as a service for the members of the Bernese research community and beyond. Research institutions are in need of local archives of mouse strains in the form of cryopreserved specimen for several reasons. First, researchers comply with the requirement of the 3R- (replace, reduce, refine) rules of working with animals bred for experiments in the biomedical research field. Second, cryopreservation allows to momentarily suspend the holding of live gene modified (GM) strains of mice to respond to financial and logistical housing constraints for GM strains no longer needed in experimentation. Third, it provides a back-up for unique strains of GM mice to rapidly recover strains following the loss or infection of the breeding colony. Fourth, frozen embryos and sperm allows economic and safe distribution of GM strains to collaborators around the globe. Finally, the cryopreserved specimen can be used as a source for rapidly and safely colonizing new mouse housing units with highly controlled hygiene status. Such conditions are now understood to be essential for the correct interpretation of and reliable conclusions from animal experiments.
Once frozen and stored in liquid nitrogen, frozen embryos and sperm remain fit for revitalization for decades. As soon as one of these valuable GM mouse strains are needed again, embryos can be thawed and transferred to recipient mothers carrying the embryos to term. Thawed sperm is used for in vitro fertilization (IVF) of mouse oocytes followed by embryo transfer of 2-cell stage embryos. In 2015, sperm freezing technology allowed us to create an archive of more than 100 GM mouse strains (principally in the C57BL6 background) thus complying with 3R recommendations and providing space for new projects and GM strains. This was achieved by weekly freezing of sperm from up to 4 strains of GM mice and testing the quality of the frozen sperm by IVF the following week. Cryopreservation of the 2-cell stage embryos created from IVF are also frozen to speed up the eventual revitalization by embryo transfer.
Production genetically modified mouse strains
Genetically engineered rodents are of great value for basic research and may even be indispensably important for modeling diseases and developing therapeutic strategies for clinical applications. The growing number of gene modified (GM) mouse strains accessible via international research consortia reflects the dependence of current biomedical research on such mouse models for the functional analysis of biological processes in the context of the whole organism. Mouse models developed by international consortia in high throughput procedures are however limited to standard constitutive or conditional loss of function approaches. Subtler genetic alterations still have to be created individually and thus locally. We perform pronuclear injections (PNI) into mouse zygotes for the production of transgenic founder mice thus creating gain-of-function variants, new reporter strains and component strains of inducible expression systems. Furthermore, we are employing the CRISPR/Cas9 system of designer nucleases for the generation of knock-out and knock-in alleles by PNI.
For additional information and consulting, please contact Dr. Urban Deutsch and PD Dr. Charaf Benarafa.
This service is supported by equipment from the Medical Faculty and the Genaxen Foundation.
A price list for our services can be found on this PDF: Flyer_Cryo_IVF_Tg_2015.pdf (PDF, 179KB)