A C57BL/6J-congenic version of this strain is available as Stock No. 007909.
Ai9 is a Cre reporter allele that has a loxP-flanked STOP cassette preventing transcription of a CAG promoter-driven red fluorescent protein variant (tdTomato) - all inserted into the Gt(ROSA)26Sor locus. Ai9 mice express robust tdTomato fluorescence following Cre-mediated recombination.
The Ai9 allele is very similar in design to the Ai14 allele (Stock No. 007914) - differing only in the presence (Ai9) or absence (Ai14) of an att site-flanked neo selection cassette at the 3' end of the targeted allele.
Importantly, both Ai9 and Ai14 may exhibit low levels of tdTomato expression prior to exposure to Cre recombinase - but the tdTomato expression levels after Cre recombination are significantly greater than those baseline levels. As such, it is recommended that researchers include Cre-negative controls to establish the baseline tdTomato levels in their experiments.
Hongkui Zeng, Allen Institute for Brain Science
Genetic Background | Generation |
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|
Allele Type | Gene Symbol | Gene Name |
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Targeted (Conditional ready (e.g. floxed), Reporter) | Gt(ROSA)26Sor | gene trap ROSA 26, Philippe Soriano |
Ai9 mice homozygous for this Rosa-CAG-LSL-tdTomato-WPRE conditional allele are viable and fertile. A loxP-flanked STOP cassette is designed to prevent transcription of the red fluorescent protein variant tdTomato (see below). When bred to mice that express Cre recombinase, the resulting offspring will have the STOP cassette deleted in the cre-expressing tissue(s) - resulting in robust tdTomato fluorescence. Because this CAG promoter-driven reporter construct is inserted into the Gt(ROSA)26Sor locus, robust tdTomato expression is determined by which tissue(s) express Cre recombinase. These Ai9 mice are useful as a Cre reporter strain - expressing tdTomato fluorescence following Cre-mediated recombination.
Importantly, the donating investigator reports that very low levels of tdTomato expression may be present prior to introduction of Cre recombinase - but the tdTomato expression levels after Cre recombination are significantly greater than those baseline levels. As such, it is recommended that researchers include Cre-negative Ai9 controls to establish the baseline tdTomato levels in their experiments.
Of note, the FRT sites flanking the mutation allow for additional targeted replacement of the reporter sequences through Flp-mediated recombination if so desired. Similarly, the attB/attP-flanked selection cassette may be removed by introduction of the site-specific bacteriophage PhiC31 integrase if so desired.
For characterization information, see images at the Allen Institute for Brain Science website (Ai9 images).
The Allen Institute for Brain Science website has specific characterization information for several Cre Driver and Cre Reporter lines. Please see their website for images of Allen Institute for Brain Science experiments performed with all lines.
The Ai9 allele is very similar in design to the Ai14 allele (Stock No. 007914) - differing only in the presence (Ai9) or absence (Ai14) of an att site-flanked selection cassette at the 3' end of the targeted allele. Specifically, the Ai9 allele (Gt(ROSA)26Sortm9(CAG-tdTomato)Hze) is designed as Rosa26::CAG::FRT::loxP-STOP-loxP::tdTomato::WPRE::polyA::attB-PGK-FRT-neo-polyA-attP, whereas the Ai14 allele (Gt(ROSA)26Sortm14(CAG-tdTomato)Hze) is designed as Rosa26::CAG::FRT::loxP-STOP-loxP::tdTomato::WPRE::polyA::attL.
The Rosa-CAG-LSL-tdTomato-WPRE targeting vector was designed with (from 5' to 3') a CMV-IE enhancer/chicken beta-actin/rabbit beta-globin hybrid promoter (CAG), an FRT site, a loxP-flanked STOP cassette (with stop codons in all 3 reading frames and a triple polyA signal), tdTomato sequence (a non-oligomerizing DsRed fluorescent protein variant with a 12 residue linker fusing two copies of the protein [tandem dimer]), a woodchuck hepatitis virus post-transcriptional regulatory element (WPRE; to enhance the mRNA transcript stability), a polyA signal, and an attB/attP-flanked PGK-FRT-Neo-polyA cassette. This entire construct was inserted between exons 1 and 2 of the Gt(ROSA)26Sor locus via electroporation of (129S6/SvEvTac x C57BL/6)F1-derived G4 embryonic stem (ES) cells. Correctly targeted ES cells (clone Ai9) were selected and chimeric males were bred to C57BL/6J females. The resulting Ai9 mice were then backcrossed to C57BL/6J for at least one generation prior to arrival at The Jackson Laboratory. These Ai9 mice on a B6;129S6 mixed genetic background are designated Stock No. 007905.
Expressed Gene | RFP, Red Fluorescent Protein, coral |
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Site of Expression | A floxed STOP prevents transcription of red fluorescent protein variant (tdTomato) until mice are bred to a Cre strain. Resulting offspring express tdTomato in a pattern dictated by the Cre promoter. |
Allele Name | targeted mutation 9, Hongkui Zeng |
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Allele Type | Targeted (Conditional ready (e.g. floxed), Reporter) |
Allele Synonym(s) | Ai9; Ai9(RCL-tdT; R26LSL-tdTomato; ROSA:lxp-stp-lxp:tdTomato; Rosa26Tomato; Rosa-CAG-LSL-tdTomato-WPRE; Rosa-LSL-TdTomato; Rs-tdTomato-R |
Gene Symbol and Name | Gt(ROSA)26Sor, gene trap ROSA 26, Philippe Soriano |
Gene Synonym(s) | |
Expressed Gene | RFP, Red Fluorescent Protein, coral |
Site of Expression | A floxed STOP prevents transcription of red fluorescent protein variant (tdTomato) until mice are bred to a Cre strain. Resulting offspring express tdTomato in a pattern dictated by the Cre promoter. |
Strain of Origin | (129S6/SvEvTac x C57BL/6NCrl)F1 |
Chromosome | 6 |
General Note | This allele was used to generate Gt(ROSA)26Sorem1(CAG-tdTomato)Jahe |
Molecular Note | The Rosa-CAG-LSL-tdTomato-WPRE targeting vector was designed with (from 5' to 3') a CMV-IE enhancer/chicken beta-actin/rabbit beta-globin hybrid promoter (CAG), an FRT site, a loxP-flanked STOP cassette (with stop codons in all 3 reading frames and a triple polyA signal), tdTomato sequence (a non-oligomerizing DsRed fluorescent protein variant with a 12 residue linker fusing two copies of the protein (tandem dimer)), a woodchuck hepatitis virus post-transcriptional regulatory element (WPRE; to enhance the mRNA transcript stability), a polyA signal, and an attB/attP-flanked PGK-FRT-Neo-polyA cassette. This entire construct was inserted between exons 1 and 2 of the Gt(ROSA)26Sor locus. |
Mutations Made By | Hongkui Zeng, Allen Institute for Brain Science |
When maintaining a live colony, homozygous mice may be bred.
When using the Ai9 or Ai9(RCL-tdT) mouse strain in a publication, please cite the originating article(s) and include JAX stock #007905 in your Materials and Methods section.
Facility Barrier Level Descriptions
Service/Product | Description | Price |
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Heterozygous for Gt(ROSA)26Sor<tm9(CAG-tdTomato)Hze> |
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The Jackson Laboratory has rigorous genetic quality control and mutant gene genotyping programs to ensure the genetic background of JAX® Mice strains as well as the genotypes of strains with identified molecular mutations. JAX® Mice strains are only made available to researchers after meeting our standards. However, the phenotype of each strain may not be fully characterized and/or captured in the strain data sheets. Therefore, we cannot guarantee a strain's phenotype will meet all expectations. To ensure that JAX® Mice will meet the needs of individual research projects or when requesting a strain that is new to your research, we suggest ordering and performing tests on a small number of mice to determine suitability for your particular project. We do not guarantee breeding performance and therefore suggest that investigators order more than one breeding pair to avoid delays in their research.
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