A Guide for What to do Before and After You Receive Your Mice.
Generating a genetically modified mouse model can take anywhere from 6-12 months to get to the stage of F1 germline confirmed, heterozygous mice. While your model is being created, it is imperative to develop a plan for managing and maintaining the mouse colony you will use for your experiments.
Even before you have your mouse model in hand, be it from a collaborator, a company, or something you are developing in your own lab, thinking ahead will save time and money. Genetic engineering can result in unexpected or complex phenotypes. During the initial planning stage for working with genetically engineered mice, one can benefit from expert help on experimental design and mouse colony management. At ingenious, our scientists are here to help you during every step of the process. From mouse model design through mouse colony management, we are with you- every step of the way.
Here we share considerations and resources to help prepare you for managing your genetically engineered mice:
a. Develop and test genotyping strategies on mouse genomic DNA. Make sure you have a straight forward and effective PCR methodology for quick identification of positive mice, as well as a validated long-range PCR or Southern blotting procedures for confirming proper, single copy integration of your targeted mutation.
b. Investigate the number, sex and age of the mice you will need in order to produce statistically significant data for your experiments, while also minding the 3R’s. Generating a large colony of mice can take significant time and resources. At ingenious, we offer a cohort development software program that can output different scenarios in terms of timelines and animal numbers, of which you can choose the scenario that best fits your lab’s needs. This is a good way to quickly ramp up your mouse colony. For more information about our cohort development software, please contact us.
c. Consider the transgenic mouse lines you will need in addition to your custom mouse model (tissue-specific Cre, CreERT2, tTA, tTS, etc.) in order to carry out your experiments. Such transgenic mouse lines are available through various repositories. An appropriate breeding strategy is critical to ensure efficiency and success. When working with mice carrying various genetic alterations (targeted insertions, transgenics such as Cre lines, etc.), specialized breeding and genotyping are required. Without the proper planning and know-how, an easy mistake can have a big impact on the significance and outcome of the studies. ingenious can help with breeding strategy and genotyping consultations.
d. Get your animal protocols in place before the mice arrive. Well in advance of receiving any mice, determine your institute’s requirements for import, proper handling and use of mice (IACUC regulations).
e. Consider using colony management software to keep data records organized. Lost mice can equal lost grant (we’ve seen it happen!). We have listed a number of colony management software options in our resources section.
a.First and foremost, genotype(!)your mice upon receiving them to make sure their genotype is correct and as expected. If this simple yet often overlooked first step is skipped, it can cause enormous losses in terms of time, money, and animals. For researchers who create mouse models through ingenious- we provide a genotyping guide for your model that includes primer sequences, gel pictures, and a clear reference guide, enabling anyone with basic PCR experience to perform accurate and reliable genotyping. If there are any questions about genotyping, our scientists are available by phone or email, even after we’ve delivered the mice to you.
Dr. Smith from NYU* received a conditional knockout mouse model and asked his post doc to expand the colony and generate homozygous mice for their experiments. Unfortunately the post doc did not fully understand the genotype of the mice, so they continued to breed the mice and analyze tail biopsies in search for the results that they were anticipating based on their understanding of the genotype. At the same time, the animal facility was supposed to cryopreserve the line, which did not happen. In addition the post doc noticed several times that the mouse cages were misplaced within the animal facility. One year went by when the error in genotyping was finally discovered. By then, none of the original mice were available and the mice at hand did not contain the correct integration. Because the mouse model was a requisite for the renewal of a large grant, the PI ultimately lost this funding, in addition to the time and cost spent on animal housing,genotyping, and paying the post doc’s salary. The lab now has to re-create the mouse line from the targeted ES cell clones which will take about 5 – 6 months, and additional funding which must be allocated from another source.
This outcome could have been avoided with a better understanding of the genotype and experimental goals for the project, in addition to better communication and more stringent monitoring of the mice within the animal facility.
b. Next, expand your mouse colony to keep it well-maintained and to support your experiments. During the expansion, confirm your initial mice using the PCR and screening procedures you have already tested. This requires expertise in colony management and genotyping. At ingenious we offer a variety of colony management services to help optimize breeding strategies, record keeping and mouse maintenance.
c. Crossing your mouse model to other transgenic lines (such as Cre strains) or other knockout or knockin lines may be a necessary step in order to generate the mouse model needed for your experiments. Colony management and proper genotyping are crucial to successfully complete this step.
d. Finally, phenotyping experiments are performed. You may require specialized phenotyping beyond your lab’s research expertise. A collaborator or university core facility may have the required expertise and equipment for your experiments. Reviewing your institute’s core facility services in advance will help you to plan your experiments. There are also external sources for specialized phenotyping; a quick Google search can show you which companies are available in your area.
*Research groups’ names and institutes have been changed to protect the privacy of individuals.
The following resources are helpful for developing breeding strategies and maintaining genetically modified mouse models:
Disease outbreaks can destroy an entire facility’s mouse lines, but even simple things such as a malfunctioning air conditioning can have devastating effects on mouse colonies. There can be many other reasons as to why you might need to re-derive your mouse line. Trying to re-create a mouse model from targeted ES cell clones, or worse, a targeting construct, will require significant time and cost money. Preserving sperm or embryos enables you to re-derive the mouse line much faster and cheaper. At ingenious, we offer both sperm and embryo cryopreservation, as well as storage of frozen sperm or embryos, and rederivation of the line when needed. We invite you to learn more about our post project support services.
When all else fails, call the professionals. ingenious’ post project and cohort development services provide the guidance, control, and reliability over your mouse colony that allows you to focus on your research. Utilizing proprietary prediction and modeling software, our mouse colony veterans can generate the cohorts you need within timelines and costs that best fit your lab.
And remember- Be nice to your mice!