These hypomorph Igf1m/m midi mice exhibit reduced size and IGF-1 serum levels, when compared to wildtype controls. These mice may be useful in studies of cardiac remodeling, obesity and metabolism.
Dr. Timothy Stewart
Mice homozygous for the Igf1tm2Ts mutation (also referred to as the Igf1m/m midi targeted insertion) are viable and fertile, but are small in size, reaching only approximately 60 - 65% the weight of their wild type siblings. Serum levels of IGF-1 in these mutants is 30% of wild type values. They have no gross histological abnormalities. Arterial blood pressure is higher in Igf1m/m mice than in wild type controls. The Donating Investigator reports that homozygotes are subfertile but viable, with approximately 50% of homozygous animals dying before weaning.
An entire targeting vector containing a NEO cassette inserted into exon 3 sequence, a thymidine kinase gene and vector sequences was inserted 5' of the endogenous exon 3.
The construct was electroporated into 129S7/SvEvBrd-Hprt+derived AB1 embryonic stem (ES) cells. ES cells which were carrying this site-specific insertion of the targeting construct rather than homologous recombination were injected into blastocysts. The resulting chimeric animals were tested for germline transmission, and bred to C57BL/6 mice. The mice were then bred to CD-1 outbred mice.
|Allele Name||targeted mutation 2, Timothy Stewart|
|Allele Type||Targeted (Hypomorph)|
|Allele Synonym(s)||IGF-Im; Midi allele|
|Gene Symbol and Name||Igf1, insulin-like growth factor 1|
|Strain of Origin||129S7/SvEvBrd-Hprt+|
|Molecular Note||Hypomorph. In this allele, a site specific insertion of the entire targeting vector occurred instead of homologous recombination. The construct interrupted exon 3 with a neomycin cassette, with a thymidine kinase gene and vector sequences inserted 5' of the endogenous exon 3. RT-PCR analysis demonstrated that a reduced amount of normal transcript was produced from this allele as well as a mutant transcript, and a low, but detectable level of the protein was present in sera of homozygous mice.|
|Mutations Made By|| |
Dr. Timothy Stewart
When maintaining a live colony, heterozygous mice may be bred together, to wildtype siblings, or to inbred mice. The Donating Investigator reports that homozygotes are subfertile but viable, with approximately 50% of homozygous animals dying before weaning.
When using the IGF-Im/m mouse strain in a publication, please cite the originating article(s) and include JAX stock #003259 in your Materials and Methods section.