These mice carry an ENU-induced mutation characterized by high threshold to electroconvulsive minimal clonic seizures and development of front- and hind limb spasms.
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Heterozygousmutants have a high threshold to electroconvulsive minimal clonic seizures (show relative resistance compared to the parental BALB/cByJ strain). When NMF31 mutant mice are stimulated transcorneally at 6 wks with 10 mA (females; or 10.5 mA at 13 wks) or 11.5 mA (males; or 12 mA at 13 wks), they, unlike BALB/cByJ mice, usually do not exhibit a robust minimal clonic seizure. However, mutants do not appear to be resistant to pentylenetetrazole (PTZ)-induced seizures. For example, when challenged with PTZ at 80 mg/kg (single subcutaneous dose) and observed for 30 minutes, the incidence of (7/16) or mean latency (9m, 21s) to generalized seizure was not significantly different from that of BALB/cByJ (6/10; 8min, 47s). Using other seizure endpoints (clonus, tonic hind limb extension) similar results were observed. This colony is currently maintained through matings of heterozygotes with +/+.
Homozygous mutants develop front- and hind limb spasms suggestive of seizure like behavior at approximately 3-6 days of age. These pups are virtually unable to move around, exhibit intermittent, intense front limb spasms, which move paws close to the chest,and hind limb spasms during which the hind limbs are completely extended backward, i.e. their hind limb position looks similar to that observed during maximal tonic hind limb extension seizures; they remain in this position for several seconds. The mutants appear to breath with difficulty and die a few days following onset of the overt phenotype.
NMF31 was mapped as a dominant trait in 50 N2 backcross mice using a seizure severity score combined from two independent tests as phenotype. The data were analyzed using the non-parametric scan function of MAPMAKER/QTL. The maximum z-score was at D1Mit100, but the 95% confidence interval for the peak location is approximately +/- 10 cM.
Standard pathology work-up on 2 heterozygous mutants (206 or 462 days of age) revealed no abnormalities. There were no apparent defects in the brain; hippocampus appeared normal.
This phenotypic deviant was generated by ethylnitrosourea (ENU) mutagenesis in BALB/cByJ males (Stock No. 001026), in the Neuroscience Mutagenesis facility at The Jackson Laboratory. Mutagenized males were crossed to BALB/cByJ females; G3 descendants of the mutagenized males were selected for neurological impairment.
|Allele Name||neuroscience mutagenesis facility, 31|
|Allele Type||Chemically induced (ENU)|
|Gene Symbol and Name||Nmf31, neuroscience mutagenesis facility, 31|
|Strain of Origin||BALB/cByJ|
|Molecular Note||This phenotypic mutant was identified in an ENU mutagenesis screen.|