Phenotypes associated with this allele

• Allele Symbol: Gfap^tm1Ito
• Allele Name: targeted mutation 1, Shigeyoshi Itohara
• Allele ID: MGI:2183216
• Summary: 1 genotype

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Gfap^tm1Ito/Gfap^tm1Ito	involves: 129P2/OlaHsd * C57BL/6J	MGI:2677142

Genotype
MGI:2677142

hm1

• Allelic Composition: Gfap^tm1Ito/Gfap^tm1Ito
• Genetic Background: involves: 129P2/OlaHsd * C57BL/6J

• ♀: phenotype observed in females
• ♂: phenotype observed in males
• N: normal phenotype

nervous system

nervous system phenotype ( J:32098 )

N • homozygotes display normal cerebellar cytoarchitecture relative to wild-type controls, except for the absence of GFAP filaments

N • at 4-6 weeks of age, homozygotes show normal excitatory synaptic transmission from parallel fibers (PFs) or climbing fibers (CFs) to Purkinje cells (PCs)

N • mutant PCs display normal short-term synaptic plasticity to paired stimuli relative to wild-type controls

N • mutant PCs show no differences in dendritic Ca²⁺ spikes evoked by CF inputs or by depolarizing current injection relative to wild-type controls

N • no persistent multiple innervation of PCs by CFs is observed in the adult cerebellum

abnormal excitatory postsynaptic potential ( J:32098 )

• long term potentaion (LTP) of field EPSPs in the CA1 region of the hippocampus is normal after theta-burst stimulation

• at 30 min after conjunctive stimulation of PFs and CFs by five pulse trains delivered every 2 s for 10 min, the relative changes in the rising slope of PF EPSPs are significantly different between wild-type and mutant PCs (-20.0% +/- 5.6% vs +22.7% +/- 8.3%, respectively)

• however, no significant differences between wild-type and mutant PCs are noted in the rising slope of PF EPSPs at 30 min after CF stimulation alone

reduced long-term depression ( J:32098 )

• homozygotes exhibit cerebellar long term depression (LTD) deficiency: unlike in wild-type controls, simultaneous stimulation of PFs and CFs fails to evoke LTD and results in a slight potentiation at the mutant PF-PC synapses

• in contrast, homozygotes display normal LTP in the hippocampal CA1 region

behavior/neurological

behavior/neurological phenotype ( J:32098 )

N • homozygotes exhibit normal motor coordination in the rotating rod, rope climbing and runway tasks

N • homozygotes learn the rotating rod task as efficiently as wild-type controls

N • no ataxia, tremors or differences in horizontal and vertical movements are observed

abnormal eye blink conditioning behavior ( J:32098 )

• homozygotes display impaired eyeblink conditioning when a conditioned stimulus (tone 1 kHz, 352 ms, 80 db) is paired with a periorbital shock (100 ms, 100 Hz pulses) as an unconditioned stimuls for 8 days

• unlike wild-type controls which display a gradual increase in the percent of conditioned responses (CR%) until the 7th session (~70%), homozygotes show only a moderate increase of CR% for the first 3 sessions and reach a plateau (~30-40%) for subsequent sessions

• although CRs in the first session appear unaffected, CRs in the 7th and 8th sessions are significantly lower in mutant mice relative to wild-type controls

• however, periorbital shock sensitivity is normal and both CR onset and peak latencies remain intact, suggesting normal CR kinetics