As a scientist, you have enough on your plate. Not sure which type of transgenic mouse would work best for your experiment? We’ve summarized some of our most popular transgenic mouse services and model types below. Don’t see the exact fit for your application? Contact us for personal assistance designing the customized mouse model that is right for you.
“I’ve been working with iTL over the past 5 years in the production of 3 different genetically altered mice. Not only did iTL help in the design of the mice, but the entire process was transparent with the opportunity at any time along the way to discuss my questions or concerns with scientists who had significant insight into the process. The mice were delivered on time, as billed!”– Raghu Mirmira, MD, PhD University of Chicago
Transgenic mice, by definition, are mice that have foreign DNA added into their genome. When these models were first created it was only possible to insert new sequences randomly with no control over their final genomic location. This random integration of DNA into the genome can, and often does, create a whole host of totally unpredictable problems, such as interrupting an existing gene or leaving the new sequence somewhere in the genome that is prone to silencing, effectively eliminating any expression of your transgene. Customized genetically modified (transgenic) models heavily impact the scientific value of your studies, as the models are designed to specifically address your scientific questions while avoiding the unpredictable complications possible in genetically modified models.
Effective research depends on finding the most relevant model for your application. When your project calls for targeting transgenesis technology, our team of specialists offer an integrated solution for the creation of your transgenic mouse model. Below, we have outlined some of our most popular transgenic mouse model types. With ingenious, you think it up, we knock it out (or in).
Targeted transgenic insertions were developed to circumvent the silencing and gene interruption problems encountered with random insertion of foreign DNA into the genome. One such targeted insertion site is the Rosa26 locus, discovered by Philippe Soriano’s lab in 1991. The Rosa26 locus was identified by randomly inserting Gen-ROSAβgeo provirus (genetic material of a virus) DNA into the mouse genome. The investigators used a low multiplicity of infection (ratio of viral genomes added per cell) in order to insert a single copy of provirus DNA into the genome [1]. The observable effect in this case was LacZ staining afforded by the βgeo reporter gene present in the Gen-ROSAβgeo proviral DNA. Mouse embryos expressing βgeo at the Rosa26 locus (Rosa26βgeo) expressed LacZ ubiquitously in every tissue and at every developmental stage [2].
Discovery of the Rosa26 locus revolutionized the development of knockin transgenic mouse models by creating a genomic safe harbor (GSH) for transgenes, or a targeted insertion site for foreign DNA that does not impact the growth, development or fertility of the resulting transgenic mice due to the integration of foreign DNA into the genome. At ingenious, we utilize proprietary technologies such as Rapid-Rosa26™ to streamline the incorporation of your transgene of interest at the mouse Rosa26 locus for either constitutive (always on) or conditional (regulated) expression of your desired transgene.
Insertion of transgenes into a genomic safe harbor (GSH) works well for some experimental applications, but some experiments require expression of a transgene that is controlled by specific endogenous transcriptional elements. cDNA knockin technology can achieve this goal in one of two ways: by replacing a target gene with your desired transgene (target gene replacement) or by inserting your transgene downstream of a target gene (target gene co-expression). The strength of cDNA knockin technology is the unique ability to use the existing genomic transcriptional elements of a target gene to drive expression of your transgene of interest.
First, let’s look at target gene replacement. In this scenario, we are replacing a target gene with a cDNA (protein coding sequence) of your transgene of interest to, for example, correct a mutated gene or establish the different functions of a multigene family, where phenotypes differ depending on which member of the multigene family is expressed. The first step to developing such a model is the creation of a targeting vector containing the cDNA sequence flanked by genomic sequences that will precisely target the transgene insertion. Homologous recombination is triggered when the vector is introduced into cells and the genomic sequences in the vector match up to identical sequences in the genome. The result is a modified gene with the transgene cDNA expressed under the control of the target gene transcriptional elements.
Co-expression of a target gene with another transgene is an equally powerful tool. This technique can be used to determine expression patterns of the target gene or establish the fate of cells expressing the target gene by co-expressing a reporter transgene such as β-galactosidase or green fluorescent protein (GFP). The technology can also be utilized to create a Cre (site-specific DNA recombinase) line while simultaneously expressing your target gene.
In much the same manner as a gene replacement cDNA knockin, co-expression cDNA knockin technology utilizes homologous recombination to integrate a transgene cDNA vector by including regions of DNA homologous to the target gene. What differs, however, is that one of two additional sequences, either an internal ribosome entry site (IRES, 500bp) or a 2A sequence (self-cleaving amino acid, 69bp), is required to translate 2 proteins from a single mRNA transcript.
IRES sequences are sequences that allow ribosomes to bind and translate RNA into protein by a process called cap-independent translation. The sequences were first discovered in viruses in 1988 and ensure the translation of viral proteins even when host translation is inhibited. IRES sequences provide lower levels of protein expression compared to protein expression achieved from translation initiated at a 5’ cap. Therefore using the IRES strategy will result in the second gene being expressed at a lower level than the first.
When equal expression of two co-expressed proteins is required in a knockin mouse model, addition of a 2A self-cleaving peptide sequence provides a good alternative. 2A self-cleaving peptides are between 18 and 22 amino acids in length and were also originally discovered in viral genomes. As it’s translated the 2A sequence causes a break in the peptide backbone resulting in the production of two separate proteins from a single mRNA and equal expression of both proteins. The 2A peptide sequence inserted between the two co-expressed genes of your knockin model will therefore add an additional ~20 amino acids to the C-terminus of the first protein and 1 proline residue to the N-terminus of the second protein.
ingenious targeting laboratory has been in business for over 20 years designing and developing custom transgenic mouse models for thousands of scientific studies just like yours. Our knowledgeable, experienced scientific consultants provide personalized guidance through every step of our transgenic mouse services, offering both traditional and cutting-edge technologies and streamlined transgenic mouse services aimed at providing you with a targeted mouse model ready for your study. The proprietary technologies developed at ingenious ensure that our team will succeed where others have failed.
We offer efficient, economical technologies utilizing the Rosa26 locus aimed at simplifying the development of transgenic knockin mouse models. The Rapid-Rosa26™ Targeting service offered exclusively by ingenious utilizes optimized gene targeting strategies with predesigned vectors to streamline the integration of your transgene into the Rosa26 locus. Additionally, Rapid-Rosa26™ Targeting can be paired with a number of enhancing cassette options to provide conditional expression of your transgene.
Scientists that have worked with transgenic mouse lines understand that a great deal of effort is required to maintain a transgenic mouse colony. Robust research studies require large cohorts of mice with a specific background strain, sex and age, which in turn require a great deal of planning and genotyping. Many research laboratories simply don’t have the manpower to spare for colony management and genotyping, and are reluctant to delegate such an important task to undergraduates. At ingenious, we make it easy for you to protect your investment after using our transgenic mouse services by leaving the cryopreserving and colony management to us.
Losing a transgenic mouse line is rarely intentional, but it does happen, and often with disastrous consequences. Genotyping and breeding difficulties can arise seemingly from nowhere–noise or vibration near an animal housing facility, disease, mixups during breeding, or inadvertent contamination of PCR reagents, to name just a few. Whether you plan to perform all of your own colony management or not, ingenious offers several cryopreservation services aimed at minimizing research downtime when the unthinkable happens.
Sperm cryopreservation is a reliable, efficient and economical way to preserve transgenic mouse lines. Sperm are collected from two male mice and a motility test is completed for thawed sperm. This service follows thawed cryopreserved sperm through in vitro fertilization (IVF) all the way to the blastocyst stage to ensure sperm fertility. ingenious offers many different storage plans to fit your specific needs and a cryorecovery service is available, if needed, to successfully reestablish your mouse line.
Sperm cryopreservation presents a number of additional benefits beyond rederiving a transgenic mouse line. Cryopreserved mouse sperm allows easy distribution of your transgenic line to other researchers and easy restoration of a specified and opportunistic pathogen free (SOPF) mouse line. There may also be a significant financial benefit to cryopreserving transgenic mouse line sperm for low use strains rather than maintaining a live colony, and having cryopreserved sperm can also serve to limit the genetic drift of a colony. The sperm cryopreservation method is best suited to transgenic mice possessing single mutations on inbred backgrounds.
Embryo cryopreservation is an alternative method to preserve your transgenic mouse line. While the method requires more mice from your colony to achieve, the preserved embryos will maintain the correct genotype of your transgene (homozygous versus heterozygous) and the specific genetic background of the mice. This may be advantageous when homozygous mice are required and transgenic sperm cryorecovery generates only heterozygous pups. Embryo cryopreservation is best suited for transgenic mice with multiple mutations.
Are you new to transgenic mouse colony management or just don’t have the resources for the task? ingenious provides comprehensive mouse breeding and colony management services, whether you require a small or large cohort of homozygous or heterozygous transgenic mice and age-matched controls. Our highly skilled team genotypes all mice and validates all mouse lines based on optimized PCR protocols and tightly controls all animal housing costs. Based on your research requirements, we can time the delivery of age-matched experimental and control cohorts directly to your facility. We can additionally cross your transgenic mouse with a Cre (or tTA, tTS or CreERT) line, creating a conditionally expressed transgenic mouse line.
Depending on the effects your transgene may have on mouse fertility and viability, three different breeding schemes are possible for your new transgenic mouse colony. With each breeding scheme, different proportions of heterozygous and homozygous offspring will be produced and genotyping may or may not be required, affecting your costs. Each breeding scheme is outlined below, along with the specific scenario in which it is used and offspring genotypes produced.
ingenious also provides transgenic mouse colony management assistance for those laboratories unfamiliar with the technologies and procedures involved with caring for their transgenic mice. We facilitate the teaching and training of staff members on an as needed basis, as defined by the client, to ensure the optimization of all colony management procedures. Additionally, we assist in setting up breeding schemes to match future needs and database management. ingenious uses SoftMouse software for all mouse colony management.
Genotyping your mouse colony is simple in theory, but can be difficult in practice. Establishing the correct genotypes of your mouse colony with absolute certainty is imperative for sound research studies and can avoid the costly scenario of losing months worth of work due to genotype uncertainty and inconsistent results. At ingenious, our PCR experts minimize PCR inhibitors in extracted mouse DNA samples and optimize our PCR to ensure efficient, highly specific reactions. We test your transgenic mouse DNA under rigorously controlled conditions so you can have 100% confidence in our genotyping. We offer genotyping to distinguish between heterozygous and homozygous WT and mutant mice and testing for multiple transgenes per mouse. Outsourcing colony genotyping to the experts at ingenious may be some of the smartest research dollars you could ever spend.
ingenious provides tissue harvesting services for researchers that require mouse tissues but not an entire mouse. We can harvest nearly any tissue you require, prepared to your specifications, and delivered directly to your facility. Our organ, tissue and blood extractions are performed by highly experienced surgeons using the most stringent aseptic techniques. We routinely collect over 75 different specimens and special requests are considered.
Not sure whether you should house your own transgenic mouse colony or outsource the work to ingenious? We provide you the cost breakdown of maintaining a live mouse colony at the cohort size, sex and age you require with our free online Breeding Planner. By entering the number of homozygous transgenic, heterozygous and WT males and females you need and the costs to genotype and house each mouse, you can get an accurate picture of the amount of time and money that will be required to build up your transgenic mouse colony. Importantly, the Breeding Planner also includes detailed breeding process milestones and a breeding strategy diagram that will assist your staff in planning the breeding crosses and achieving milestones set to keep the colony on schedule. Does it all sound like a lot of work? Contact us about outsourcing your colony breeding to the experts at ingenious.
1) Friedrich G1, Soriano P. 1991. Promoter traps in embryonic stem cells: a genetic screen to identify and mutate developmental genes in mice. Genes Dev5(9): 1513-23.
2) Zambrowicz BP, Imamoto A, Fiering S, Herzenberg LA, Kerr WG, Soriano P. 1997. Disruption of overlapping transcripts in the ROSA beta geo 26 gene trap strain leads to widespread expression of beta-galactosidase in mouse embryos and hematopoietic cells. Proc Natl Acad Sci USA94(8): 3789-94.
3) Kisseberth WC, Brettingen NT, Lohse JK, Sandgren EP. 1999. Ubiquitous expression of marker transgenes in mice and rats. Dev Biol214(1): 128-38.
The model you design is the model we deliver.
Assurance of your mouse model, not just your money back.
Our proprietary technologies save time and money.
Phone: +1 (631) 468-8530
