Homozygotes are generated in normal proportions from heterozygous intercrosses and homozygotes breed successfully. Homozygotes have compensated hemolysis, with decreased hematocrit, decreased mean corpuscular volume, decreased mean corpuscular hemoglobin, decreased mean corpuscular hemoglobin concentration, and very high reticulocyte numbers. The red blood cells are small and varied in shape including spherocytes, spherostomatocytes, and rounded eliptocytes. These red blood cells have increased osmotic fragility and there is increased iron in the spleen, which is enlarged. Homozygotes display impaired performance in fear conditioning and water maze assessments. There is impairment in CA1 short and long term synaptic plasticity and assessments of hippocampal slices shows an increased input-output relationship.
This targeted mutation was generated in 129S4/SvJae-derived J1 ES cells and male chimeras were bred to C57BL/6J females. The mutation was subsequently backcrossed onto C57BL/6J and intercrossed to homzygosity. Embryos were generated for cryopreservation from homozygous pairs at generation N13F2.
|Allele Name||targeted mutation 1, Luanne L Peters|
|Allele Type||Targeted (Null/Knockout)|
|Allele Synonym(s)||band 3-; beta-adducin-|
|Gene Symbol and Name||Add2, adducin 2 (beta)|
|Strain of Origin||129S4/SvJae|
|Molecular Note||A neomycin resistance cassette replaced a genomic fragment containing exons 9 to 13. Western blot analysis did not detect protein in RBC ghosts from homozygous mutant mice. Northern blot analysis using a probe for exons 9 to 12 did not detect transcript in homozygous mutant brain, spleen, or kidney. Northern blots using a neoR gene probe indicated that in homozygous mutant mice, transcripts are produced from antisense neoR sequence, and in spleen membranes the 4kb chimeric transcript is translated into a 55kDa protein that is detectable by Western blot. RT-PCR analysis detected a transcript that is a direct splice from exon 8 to exon 14, and which in homozygous mutant brain and spleen does not produce a polypeptide that is detectable by Western blot analysis.|