The outcome of any given experiment is not guaranteed. The staff of this Resource has years of experience and routinely performs the services offered with success. However, variability can be due to the nature of the materials originating from Investigator's laboratories, biological variability of the mice, or sometimes simply bad luck. Thus, experiments do not always provide the desired results. The Resource will not be obliged to provide service when the PI fails to provide materials or results that are of judged to be of insufficient quality. Any deviation from the routine fee scheduled will be reviewed and approved by the director of this resource.
For pure C57Bl/6 strains we guarantee injection of at least 50 to 200 embryos per experimental day. We cannot guarantee a minimum number of injected embryos for other commercially available or for investigator-provided lines.
Limited genome editing guarantee: The efficiency of gene editing projects depends on the design, reagent quality, the genetic locus, and the type of edit desired. VGER guarantees delivery of viable (see below) genome edits for all Type1 and 2 full-service projects in approved mouse strains with the required number of injection days. Projects that do not utilize a VGER design or that utilize reagents from other sources are not guaranteed.
Non-viable genome edits: Genome editing may cause embryonic or perinatal lethality or infertility, resulting in the inability to establish a viable line. This is suggested by any of the following observations: small F0 litter size with animals containing only WT, non-frameshift, or heterozygous frameshift mutant alleles. We will notify you if we suspect that your gene editing project is causing lethality or infertility.
Undesired mutations: Genome edited mice are usually mosaic and will often contain small insertions or deletions where cleavage occurred and was repaired by non-homologous end joining. Random DNA integrations and/or mutations in the DNA sequence, particularly for longer insertions, may occur. Off-target editing can occur. VGER chooses guide RNAs with low off-target prediction scores to minimize the risk of edits at unwanted sites. In mice, off-target mutations not in linkage with the desired edit may be segregated over several generations of backcrossing to a WT strain. VGER is not liable for models containing off-target mutations, random insertions, or mutations in the DNA sequence introduced during commercial synthesis or during integration into the genome.
The Vanderbilt Genome Editing Resource will repeat specific experiments as necessary to achieve the deliverables that have been specified for each service type. However, any additional service beyond that specified for each service type must be approved by the Manager and Director of this Resource and will usually require an additional charge.
Working with Preexisting Mutations for Microinjection
The VGER is willing to utilize a mouse line with preexisting mutations for microinjections. However, this does generate additional complexities and effort to perform this type of experiment. Such experiments will require additional communication with the Manager of this resource and the Investigator’s lab. The Investigator’s lab will be responsible for a number of aspects of such a project including, but not limited to the following:
The investigator’s lab will need to maintain 8 to 10 stud males which must be singly housed during the experiment timeline. Scheduling of such experiments will be done so that it is least disruptive to the VGER routine schedule. The VGER will superovulate wildtype females and submit a transfer request for the DAC to move to the superovulated females to the investigator’s room on a specific date and time. Once received, the Investigator’s lab will be responsible for mating the females with the stud males. This will need to be completed by 2 pm on the day the females are moved to the Investigator’s room. The following morning, someone from the Investigator’s lab will meet the VGER to retrieve the females. A minimum of 50 fertile embryos will be necessary for microinjection to occur. If fewer than 50 fertile embryos are obtained, the Investigator will be responsible for the cost of ½ of an injection day. Due to the intricacy of such experiments, no guarantees are provided for an injection day to be completed due to the low number of fertile embryos. The VGER also does not guarantee that the desired mutation will be achieved. The Investigator will likely need to schedule multiple injection days for this type of procedure to be successful.
If your experiment does not allow for the use of wildtype females mated with the stud males that contain the preexisting mutation, please contact the Manager of this resource to discuss. This is usually a much more intensive mating scheme for the Investigator’s lab and would require 8 to 10 females at 3 to 5 weeks of age for each injection day planned in addition to the 8 to 10 stud males for mating. The Investigator’s animal protocol would also need modification to allow for the superovulation of the females to be used for microinjection.
Authentication of Key Biological and/or Chemical Resources
The responsibility for authenticating the mice generated by the Vanderbilt Genome Editing Resource (VGER) lies principally with the users of the resource. However, we strive to the extent possible to assure that all genetically-altered mice developed through this resource have exactly the changes in DNA content that the investigator wants. To help assure this, all projects are reviewed by the Director of the VGER to ensure that they have been properly designed and are feasible. Instructions are provided as part of the service forms for the acquisition and preparation of the reagents that are used in the blastocyst or pronuclear microinjection procedures. Authentication of the mice that are obtained is typically done in two stages. The first step is to confirm that the genetic alteration is present and can be routinely identified by standard genotyping and/or DNA sequencing methods. The second step is to determine whether the genetic manuscript functions as intended. Validation of functionality may involve multiple assays, depending on the nature of the genetic mutation.
Mice are sensitive to their physical environment, with noise and vibration being known to affect reproductive success and pup survival. Control of these variables lies with the Division of Animal Care (DAC) and is not the responsibility of the VGER.