Transgenic and Embryonic Stem Cell Core Frequently Asked Questions

I want to generate C57BL/6 transgenic mice instead of FVB. Do you offer C57BL/6 pronuclear injection?

Although we typically use FVB fertilized eggs to generate transgenic mice, it is possible to use C57BL/6 eggs. However, since C57BL/6 mice are usually more expensive than FVB and it is harder to obtain transgenics from them, we need to ask investigators to pay an additional fee for this special service. Please contact the Core director for more information.

I decided to use another service provider. Can I cancel my request?

We purchase necessary mice and reagents based on your request. You can cancel your request but you may not be totally reimbursed, particularly if the project has been initiated.

I need 5 transgenic mice but received only 3 transgenic mice. Can you perform another injection without extra charges?

We guarantee 3 transgenic mice/pups or 30 potential founders whichever comes first for $1250 at CCRI. If you need more founders, you will need to submit another request with a charge of $1250. If your project is unusual and requires special consideration, please consult the Core director before starting your project.

My genotyping for ES screening did not work and I used all DNA samples I had. Can I get more of the DNA samples?

Initially the 288 colonies are frozen in 96 well plates and cannot reliably be stored longer than 6 months. Therefore it is necessary that you finish your genotyping as soon as possible. We can prepare more DNA samples but there may be an additional charge. This is the reason that we strongly recommend that you establish genotyping methods before submitting your request and that the genotyping involve Southern hybridization rather than PCR. Established protocols that work in our hands for DNA preparation and genotyping by Southern are available.

I screened all 288 colonies and obtained no positives. Can you repeat an electroporation?

The targeting efficiency will vary depending on many factors such as a vector design and targeting loci. Typically, the efficiency is 0-30 % and multiple positive clones can be obtained from 288 colonies. If you do not obtain any positives in 288, there is likely an unanticipated biological reason for the problem (lack of sufficient homology, lack of use of isogenic DNA, lethality in ES cells, other). These problems can usually be avoided by consulting with the Core director when you first design a construct. Since electroporation is labor-intensive and costly, another electroporation will require additional charges, unless there was a technical problem within the Core.

I want to obtain transgenic animals as soon as possible because I know my competitor has already generated one or because my grant submission due date is approaching. Can you prioritize my project?

We typically decide service order based on the date we received a core use request form and the date we received DNA constructs. The order is finalized at our weekly core meeting. Since everyone’s project is high priority, we ask that investigators understand that we cannot bump other projects that were submitted before theirs.

I requested mouse strains and they can ship frozen embryos to me. Can you recover the mice?

It depends on how they froze down the embryos. We use an equilibrium method to freeze 8 cell stage embryos. If a non-equilibrium method or 2 cell stage embryos were used, the recovery may be difficult. But we can certainly try. Please consult the Core director.

My mice are in quarantine. Can you rederive and transfer the mice into the barrier facility?

We have done this for PIs several times in the past, but before we can begin rederivation of mice in quarantine it must be discussed with the Vivarium Veterinary Director Jim Cooper and then the Core director.