Mice homozygous for the spontaneous mutation stargazer (Cacng2stg) are characterized by their smaller body size, slightly ataxic gait, and abnormal head movements. Their aberrant brain wave patterns are similar to those seen in human beings with absence epilepsy.Read More +
Mice homozygous for the spontaneous mutation stargazer (Cacng2stg) are first recognizable at 14 days of age by their smaller body size and slightly ataxic gait. Female stargazer homozygous mutant mice are fertile, but most of the males are unable to breed. The mutation is named for the abnormal head movements resembling choreiform head tossing that is characteristic of these mice. The behavioral symptoms progressively worsen with age, but both males and females will live to over one year of age. Electrocorticographical recordings of stargazer mice reveal frequent, prolonged, generalized spike-wave cortical discharges with behavioral arrest. The abnormal brain wave patterns are similar to those seen in human beings with absence epilepsy. Waggler homozygotes (Cacng2stg-wag) manifest a less severe phenotype than stargazer homozygotes, but do display an ataxic gait and occasional seizures. In general, young stargazer mice are more healthy than waggler homozygotes, but if wagglers reach weaning age, they will usually live for 1 to 2 years. Homozygous waggler males and females will breed, and they display no gross neuroanatomical or histopathologic lesions.
Stargazer (Cacng2stg) arose spontaneously in strain A/J at the Jackson Laboratory in 1979. It was carried to N3F1 on the A/J strain and then outcrossed to a B6C3Fe-a/a F1 and continued on that background using the cross intercross system. It was cryopreserved in 1990 by mating heterozygotes at N20. The line that remained on the shelf readhed N40 in 2005.
|Gene Symbol and Name||a, nonagouti|
|Strain of Origin||old mutant of the mouse fancy|
|General Note||Insertion of the LV30 retrotransposon without the beta4 retrovirus sequence does not cause the nonagouti phenotype. J:278039|
|Molecular Note||Characterization of this allele shows an insertion of DNA comprised of a 5.5kb virus-like element, VL30, into the first intron of the agouti gene. The VL30 element itself contains an additional 5.5 kb sequence, flanked by 526 bp of direct repeats (beta4 retroviral sequence). The host integration site is the same as for at-2Gso and Aw-38J and includes a duplication of four nucleotides of host DNA and a deletion of 2 bp from the end of each repeat. Northern analysis of mRNA from skin of homozygotes shows a smaller agouti message and levels 8 fold lower than found in wild-type.|
|Allele Synonym(s)||gamma2stg; stg; stg-|
|Gene Symbol and Name||Cacng2, calcium channel, voltage-dependent, gamma subunit 2|
|Strain of Origin||A/J|
|General Note||Phenotypic Similarity to Human Syndrome: Absence Epilepsy J:192431, J:155872, J: 226251.|
|Molecular Note||The phenotype of the stargazer mouse has been attributed to an early transposon (ETn) insertion into intron 2 of the Cacng2 gene. RT-PCR analysis demonstrated that in addition to aberrant transcripts generated by the insertion, some normally spliced mRNA was detected, suggesting that this mutation does not represent a complete null allele.|
When using the B6C3Fe a/a-Cacng2stg/J mouse strain in a publication, please cite the originating article(s) and include JAX stock #001756 in your Materials and Methods section.