Frequently Asked Questions

To begin, we need your target gene name or Ensembl ID, desired modification type (knockout, knockin, point mutation, etc.), preferred mouse strain background (C57BL/6, 129, BALB/c), and research application. Our team will guide you through allele design strategy and selection strategy during initial consultation.

Project cost varies based on model complexity, allele design, and additional services required. Conditional knockouts with LoxP sites and humanization projects price higher than conventional knockouts. Submit your work email through our pricing guide or request a quote and we will return a fixed-fee quote within 24 hours, tailored to your specific project requirements.

After submission, a project manager contacts you within 1 business day to discuss your research goals. We provide allele design recommendations and a detailed quote. Once approved, we begin targeting vector design, generate founders, and verify germline transmission. You receive regular progress updates at each milestone.

Yes. We offer speed expansion breeding to rapidly generate cohorts, backcrossing services to achieve desired background purity, cryopreservation for colony backup, and full colony management services. Our breeding schemes are optimized for germline stability and reproducible phenotypes.

Absolutely. Our scientific team provides expert consultation on allele design strategy at no additional cost. We help select critical exons, optimize LoxP placement, choose appropriate selection markers, and design verification strategies. All designs are reviewed for germline stability and experimental utility before proceeding.

C57BL/6 is the most common background, offering excellent breeding performance, robust phenotypes, and extensive published data. BALB/c is preferred for immunology studies. FVB/N is ideal for transgenics and pronuclear injection. Background choice depends on your research application and phenotyping requirements.

Yes. We guarantee germline transmission for all mouse model generation. If initial founders fail to transmit, we generate additional founders at no extra cost until germline transmission is achieved. All germline founders are verified by PCR genotyping and breeding analysis before delivery.

Knockout mice have gene function eliminated through deletion or disruption, revealing loss of function phenotypes. Knockin mice have new DNA sequences inserted at specific loci, enabling gain of function studies, reporter expression, or humanization. Knockouts study what happens when a gene is removed; knockins study what happens when something is added.

Use conditional knockout when: (1) conventional knockout causes embryonic lethality, (2) you need tissue-specific gene deletion, (3) you want temporal control over deletion timing, or (4) you need to study adult-onset disease without developmental confounds. Conditional models use Cre-lox system to delete genes only in specific cells or at specific times.

Reporter knockin mice express fluorescent proteins (GFP, tdTomato, mCherry) or enzymatic reporters (LacZ, luciferase) under endogenous gene control. They enable: cell lineage tracing, live imaging of gene expression, isolation of specific cell populations by FACS, and visualization of tissue-specific expression patterns. Reporters reveal where and when genes are naturally expressed.

A floxed mouse has LoxP sites flanking a critical gene region (exon). By itself, the floxed allele is functional and shows no phenotype. When bred with Cre recombinase expressing mice, Cre deletes the floxed region, creating a knockout. This two-component system enables tissue-specific or inducible gene deletion depending on which Cre driver is used.

Yes. Point mutation mice introduce single nucleotide changes, small insertions, or deletions to model human disease-associated variants. This approach preserves gene expression levels while altering protein function, making it ideal for studying dominant mutations, gain of function variants, or drug resistance mutations found in human patients.

Humanized mice have mouse gene sequences replaced with human orthologs, enabling testing of human-specific therapeutics. Common targets include immune checkpoints (PD-1, PD-L1, CTLA-4), cytokines, antibody targets, and drug metabolism genes. Humanization is critical for antibody therapeutic testing, as human antibodies often do not recognize mouse proteins.

Knockin mice have DNA inserted at a specific genomic location through homologous recombination, ensuring single-copy integration at a defined locus. Transgenic mice have DNA randomly integrated, often in multiple copies at unknown locations. Knockins provide controlled expression from endogenous regulatory elements; transgenics may show variable or ectopic expression.

Yes. We can generate mice with multiple knockouts, combined knockout plus knockin, or multiple knockins at different loci. Complex models are typically built by breeding separate single-modification lines together rather than targeting multiple loci simultaneously. Our Breeding Scheme Architect tool helps plan single allele breeding strategies; contact our scientific team for guidance on multi-allele models.

Tag knockin mice have epitope tags (FLAG, HA, V5, Myc) or affinity purification tags fused to endogenous proteins. This enables: protein localization by immunostaining, co-immunoprecipitation for interaction studies, ChIP-seq for DNA binding analysis, and biochemical purification at physiological expression levels. Tags reveal native protein behavior without overexpression artifacts.

ROSA26, H11, and Hprt are safe harbor loci that permit transgene insertion without disrupting endogenous gene function. Use safe harbors for: ubiquitous reporter expression, inducible transgene systems, Cre recombinase expression, or any application requiring predictable, position-independent expression. ROSA26 is the most commonly used safe harbor for these purposes.

Cre-lox system uses Cre recombinase enzyme to delete DNA between LoxP sites. When Cre is expressed in specific tissues (using tissue-specific promoters), it deletes the floxed region only in those cells. This enables tissue-specific gene knockout. Inducible Cre systems (tamoxifen-inducible) add temporal control, allowing deletion at specific developmental stages or experimental timepoints.

Cre-lox uses Cre recombinase and LoxP sites. Flp-FRT uses Flp recombinase and FRT sites. Both enable conditional deletion, but use different recombination sites. Flp-FRT is often used to remove selection cassettes during targeting, while Cre-lox is typically used for experimental gene deletion. The two systems can be combined for sequential deletions or complex allele manipulation.

Cre driver selection depends on target tissue and timing requirements. For constitutive tissue-specific deletion, choose drivers with well-characterized expression patterns (Alb-Cre for liver, Nestin-Cre for neural). For inducible deletion, use tamoxifen-inducible CreERT2 drivers. Verify Cre expression pattern matches your target using reporter crosses before experimental use. Check for known Cre-associated phenotypes in your chosen driver line.

Germline transmission occurs when a genetic modification is passed through germ cells (sperm/eggs) in founders to offspring. Only germline-transmitted alleles can establish stable mouse lines. We verify germline transmission by breeding founders and genotyping offspring. All delivered founders are guaranteed to show germline transmission.

Critical exon is the exon whose deletion causes frameshift or removes essential protein domains, ensuring complete loss of function. Selection considers: reading frame disruption potential, proximity to translation start, domain disruption, and isoform analysis. We analyze all isoforms to ensure chosen exon deletion eliminates function in all transcript variants.

Yes. Tamoxifen-inducible Cre (CreERT2) enables temporal control over gene deletion. Cre remains inactive until tamoxifen administration activates it, allowing deletion at any chosen timepoint. This is essential for studying adult-onset disease, avoiding developmental lethality, or comparing effects of early versus late gene deletion.

Quality control includes: targeting vector sequence verification, Southern blot confirmation of correct integration, PCR genotyping of founders, germline transmission verification through breeding, karyotype analysis to ensure normal chromosomes, and expression analysis to confirm expected mRNA/protein changes. All QC data is provided with delivered animals.

C57BL/6J (Jackson Laboratory) and C57BL/6N (NIH/Taconic) are C57BL/6 substrains with minor genetic differences from decades of separate breeding. C57BL/6J is preferred for behavioral and metabolic studies. Differences include: Nnt deletion in C57BL/6J affecting metabolism, Crb1 mutation in C57BL/6N affecting retina. See our C57BL/6J vs C57BL/6N comparison for details.

C57BL/6 dominates because of: extensive phenotypic characterization, complete genome sequencing, robust breeding performance, consistent behavioral phenotypes, and the majority of published mouse studies use this background. Using C57BL/6 enables direct comparison with existing literature and publicly available resource strains.

Backcrossing breeds targeted mice to a desired background strain repeatedly to eliminate unwanted genetic contributions from the original donor strain (typically 129). Each generation removes approximately 50% of residual 129 DNA. N5 backcross (5 generations) achieves ~97% background purity. N10 achieves >99.9%. Backcrossing is essential when strain background affects phenotype or when comparing to literature using pure backgrounds.

Yes. While C57BL/6 is most common, we can generate models on BALB/c (immunology studies), FVB/N (transgenics, imaging), 129 (cancer studies), or other backgrounds. Background choice depends on application-specific requirements. We can also backcross existing models from one background to another through speed backcrossing programs.

Absolutely. Genetic background profoundly affects phenotype penetrance, disease susceptibility, and therapeutic response. The same mutation on different backgrounds can show dramatically different phenotypes. This is why background control and proper backcrossing are critical for reproducible research. Always use littermate controls from the same background.

Speed congenic uses marker-assisted selection to accelerate backcrossing from 10+ generations to 5 to 6 generations while achieving equivalent background purity. We genotype SNP markers across the genome and select breeders with maximum background recovery each generation, dramatically reducing time and cost to achieve pure background strains.

Yes. Services include: speed expansion breeding to rapidly generate experimental cohorts, maintenance breeding to preserve colonies, breeding scheme design for complex genetics, and full colony management. Our breeding facilities maintain strict pathogen-free conditions and detailed genealogy tracking for all animals.

Yes. We offer sperm cryopreservation and embryo cryopreservation for colony backup and long-term storage. Cryopreservation protects against colony loss from disease, genetic drift, or facility disruption. Frozen samples can be recovered years later through IVF or embryo transfer to re-establish lines when needed.

Rederivation cleans mouse lines of pathogens through embryo transfer or cesarean derivation into pathogen-free environments. It is needed when: importing mice from external facilities, eliminating specific pathogens from colonies, or upgrading health status. All rederived animals undergo extensive health monitoring before facility integration.

Yes. We provide PCR genotyping, Southern blot analysis, and copy number determination for all standard and study-specific alleles. Routine genotyping uses tail or ear DNA. We provide primers, protocols, and positive control DNA to enable in-house genotyping, or can perform genotyping as an ongoing service.

Yes. Our free Breeding Scheme Architect tool plans single allele crosses—including conditional knockouts, Cre driver schemes, reporters, knockins, and humanized alleles. It calculates expected genotype ratios, estimates breeding pairs needed, and maps the generation-by-generation path to your target cohort. For multi-allele or complex schemes, our scientific team provides project-specific guidance and detailed breeding protocols.

Both. We can deliver: germline-verified founders (F1 generation), expanded cohorts of specific genotypes, age-matched experimental cohorts, or ongoing colony management with regular shipments. Many researchers prefer receiving expanded cohorts ready for experiments rather than breeding founders themselves.

Yes. Our catalog models are maintained as live colonies and available for rapid delivery. Most catalog strains ship within 2 to 4 weeks. Catalog includes: humanized immune checkpoint mice (PD-1, PD-L1, CTLA-4), reporter lines, and disease models. Browse our complete catalog online.

All mice include: complete genotyping data, germline transmission verification, targeting strategy documentation, breeding genealogy, health certificates, and recommended breeding schemes. For knockouts, we can provide RT-PCR or Western blot confirming reduced/absent expression. Generated characterization packages available upon request.

We guarantee proper genetic modification and germline transmission, verified by molecular analysis. Phenotype expression depends on many factors including background strain, husbandry conditions, age, and environmental variables. Our team provides consultation on troubleshooting phenotype expression, background effects, and experimental design optimization.

Yes. All projects include lifetime technical support for: breeding questions, genotyping troubleshooting, primer design, background strain considerations, and experimental design consultation. Our scientific team has decades of mouse genetics expertise and is available to help optimize your research outcomes.

Germline stability is ensured through: targeted integration site selection in stable genomic regions, avoiding repetitive sequences, karyotype verification, multi-generation breeding confirmation, and analysis of germline transmission rates. We only deliver founders with verified stable germline transmission across multiple litters.

Our models appear in over 800 peer-reviewed publications across all major journals. Publications span oncology, neuroscience, immunology, metabolism, cardiovascular disease, and rare disease research. Browse our publications database organized by disease area, model type, and year to find relevant examples for your research area.

Yes. We welcome facility tours for potential and current clients. Tours showcase our gene targeting laboratory, microinjection suite, breeding facility, and quality control laboratory. Virtual tours and consultations are also available. Contact us to schedule a visit or virtual meeting with our scientific team.