Large-fragment Knockin Rats (ROSA26)

Large-fragment Knockin Rats (ROSA26)
  • Consistent and predictable ubiquitous gene expression
  • Large fragment up to 8kb
  • As little as 3 months

Large-fragment knockin (LFKI) rats (Rosa26) contain an exogenous gene sequence introduced at the Rosa26 locus, which avoids disruption of endogenous genes. LFKI rats (Rosa26) are common disease models and are also used to study gene function and expression patterns. In order to achieve consistent and predictable ubiquitouss/tissue-specific gene expression in your rat model, targeted insertion into the ROSA26 locus is an ideal choice. The ROSA26 locus is often referred to as a "safe harbor" locus, and has been extensively used as a transgene insertion site due to the lack of insertion site side effects and the stable ubiquitous expression of genes inserted here. Now, with the application of CRISPR-Pro-based knockin technology, large DNA fragments can be accurately introduced into the ROSA26 locus quickly and efficiently, with turnaround times as short as 3 months. We guarantee delivery of a minimum of 2 founders or 3 F1 animals for ROSA26 knockin fragments up to 2 kb. Projects with larger knockin will be evaluated case by case.


Workflow of CRISPR-Pro-mediated Large-fragment Knockin Rats (ROSA26)

workflow of CRISPR/Cas-mediated knockin rats (ROSA26)

1. ROSA26 large-fragment knockin strategy design

Tell us the gene you wish to knockin and we will design a nuclease-mediated strategy for you. This includes design of the donor vector and gRNA vectors, and selection of target sites in the gene based on our optimized algorithm that maximizes on-target nuclease activity and minimizes off-target activity. Genotyping assays based on PCR and sequencing will also be designed for the screening of founder rats.

2. Knockin vector construction

DNA vectors that express the desired nucleases and donor vector will be constructed. Where needed, the efficacy of these vectors will be tested in cell culture.

3. CRISPR-Pro injection into rat eggs

- mRNA preparation: Nuclease expression vectors will be transcribed in vitro. The resulting mRNA will be artificially capped and polyadenylated to facilitate proper translation in mammalian cells.

- Nuclease injection to obtain founders: The nuclease mRNA and donor vector will be co-injected into fertilized rat eggs, followed by implantation of the eggs into surrogate mothers to obtain offspring. In cases where the nuclease expression vectors are designed and constructed by Cyagen, we will inject as many eggs and/or target as many sites as needed to fulfill the guarantee. In cases where the nuclease expression vectors (or their mRNA products) are provided by the customer, we will inject a minimum of 200/300 eggs (based on strain) and screen pups for founders carrying desired mutation. If no founders are identified, more injections can be performed at an additional charge.

4. Knockin founder screening

Pups will be screened by PCR to identify knockin founder rats. Specifically, the site targeted by CRISPR will be PCR-amplified to reveal any insertions. Occasionally, an animal may be found to have both alleles of the target site mutated.

5. Breeding founders to obtain F1

For some projects, the generation of founder rats is the end point. However, some customers wish to have us breed the founders further to obtain F1 rats. Cyagen will breed up to 3 founders to wildtype rats of matching strain background, and genotype their offspring to obtain F1 rats bearing the large-fragment knockin.


Pricing and Turnaround Time

For projects where nuclease expression vectors are constructed by Cyagen 

Stages Service Price Turnaround time


Rosa26 large fragment knockin strategy design  Free 1-4 days
2 Nuclease expression vector/Knockin vector construction Please inquire 4-7 weeks
3  CRISPR-Pro injection to obtain knockin founders SD Please inquire 8-12 weeks
4 Long Evans Please inquire 8-16 weeks
5 Genotyping pups to identify knockin founders Please inquire 2-4 weeks
6 Breeding founders to obtain F1 Please inquire 12-18 weeks
7 (Optional) Southern blotting for Founders or F1 Please inquire 2-4 weeks

 Note: Pricing applied to projects with fragments up to 2kb in length. Larger fragments can be accommodated at an additional cost. Please refer to formal quotations for additional information.


Donor Strain Information

CRISPR ROSA26 large-fragment knockin is provided on a SD/Long Evans background, but we may be able to use other strains per your request.

>> Mouse models are also available. Learn more about CRISPR Large-fragment Knockin (ROSA26 Locus) Mouse Services.



Cyagen offers the best guarantee in the industry – we guarantee generation of ROSA26 knockin rats with inserted fragment up to 2kb. Projects with knockin fragment larger than 2 kb will be evaluated on the case by case basis. We will fully refund the client’s service fee if animals with the specified genotype are not generated (except for genetic modifications severely affecting viability, morbidity, or fertility). Given the complexity of biological systems, a particular genetic modification may not result in the desired phenotype. As such, Cyagen's guarantee covers the creation of animals with the specified genotype, not a particular phenotypic outcome in terms of transcription, protein/RNA function, or organismal biology.


Order Supporting Information 

Please see below for supporting information related to Cyagen animal orders.


Inquiries and Quote Requests

Request a quote now. Alternatively, you can always email or call 800-921-8930 to inquire about our services or obtain a quote for your project.


Why Choose Cyagen?

  • 15+ years' experience in custom animal model generation
  • 78,000+ animal models generated and delivered worldwide
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