Chimera Production
Chimeras are generated using genetically modified mouse ES cells. Generally, chimeras are used to establish mouse lines by breeding to transmit the modified ES genome. They can also be used directly for experimentation.
We can produce chimeras by several means, including morula aggregation, morula or blastocyst microinjection, and tetraploid complementation assay. The method used depends on research goals, ES cell type, the strain background of ES cells and host embryos. Genetically modified ES cells can be produced in-house by the investigator or obtained from an ES clone consortium.
Procedure
Clients not from the Weizmann Institute should contact Rebecca Haffner.
Importing an ES Clone from a Consortium
All ES clones imported from outside the WIS will have to be proven negative for the pathogens listed in IDEXX (formerly Radil) Impact I screen.
It is highly recommended to order more than one clone/mutation, if possible, and to request that the clones be karyotyped. Any clone in which less than 50% of the cells are euploid rarely transmits through the germline.
On arrival, the vial will be thawed and expanded in the ES facility by the investigator, and frozen stocks will be made for use in chimera production.
ES cells will be prepared according to our protocols and delivered to the microinjection lab by the user on the morning of injection.
We will inject/aggregate ES clones into host embryos and transfer them into pseudopregnant females to produce chimeric animals. A minimum of 50 embryos will be transferred for each line.
The resulting chimeras will be mated with test animals to screen for germline transmission. Tissue samples for genotyping from ES derived offspring will be provided on weaning.
We do not guarantee chimeras or germ-line transmission, since this is dependent on the quality of the individual ES clone. About half of the ES clones obtained from consortia retain their germ-line potential.
A chimera session will not be scheduled before IACUC approval has been granted by the IACUC Committee, which can take a few weeks and an order placed in Internal Services.
IACUC and Internal Service Orders
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 # 13. Chimera Production
Contact Dr. Rebecca Haffner for details