Phenotypes associated with this allele

• Allele Symbol: Nrn1^tm1.2Ndiv
• Allele Name: targeted mutation 1.2, Elly Nedivi
• Allele ID: MGI:5307918
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Nrn1^tm1.2Ndiv/Nrn1^tm1.2Ndiv	C57BL/6-Nrn1^tm1.2Ndiv	MGI:5307919
cx2	Nrn1^tm1.2Ndiv/Nrn1^tm1.2Ndiv Tg(Thy1-EGFP)SJrs/0	involves: C57BL/6 * CBA	MGI:5307920

Genotype
MGI:5307919

hm1

• Allelic Composition: Nrn1^tm1.2Ndiv/Nrn1^tm1.2Ndiv
• Genetic Background: C57BL/6-Nrn1^tm1.2Ndiv

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

nervous system

nervous system phenotype ( J:178970 )

N • brain weight and gross anatomy are similar to wild-type littermates at 8 weeks of age

abnormal nervous system development ( J:178970 )

• neuropil development is initially delayed but eventually reaches wild-type levels

delayed axon extension ( J:178970 )

• delay in outgrowth of retinal ganglion cell axons into the lateral geniculate nucleus such that the retinogeniculate projection area is reduced at P9 but catches up to wild-type by P90

abnormal CNS synapse formation ( J:178970 )

• fewer synapses are formed but those formed are less likely to be pruned resulting in similar synapse numbers to wild-type controls at 9 months of age

delayed CNS synapse formation ( J:178970 )

• at P7 in the dentate gyrus mEPSCs occur with lower frequency and have reduced amplitudes indicating a delay in synapse development and maturation

• however, at 2 months of age amplitudes are similar to wild-type controls

abnormal dendrite morphology ( J:178970 )

• at P15 dentate gyrus granule cells have significantly fewer branch tips per neuron

• between P 15 and P60 branch tip pruning in dentate gyrus granule cells is less pronounce compared to wild-type controls

• by 2 months of age dendritic arbors of dentate gyrus granule cells appear similar to wild-type controls

abnormal synapse morphology ( J:178970 )

• at 2 months of age in the dentate gyrus, but not in the hippocampal CA1 region, the density of asymmetric synapses on dendritic spines is reduced

abnormal postsynaptic density morphology ( J:178970 )

• at 2 months of age post-synaptic density lengths are increased by 33% compared to wild-type controls in the in the dentate gyrus, but not in the hippocampal CA1 region

abnormal miniature excitatory postsynaptic currents ( J:178970 )

• at P7 in the dentate gyrus mEPSCs occur with lower frequency and have reduced amplitudes indicating a delay in synapse development and maturation

• however, at 2 months of age amplitudes are similar to controls

growth/size/body

decreased body weight ( J:178970 )

• weigh on average 20-30% less than wild-type littermates

decreased body length ( J:178970 )

• 3% shorter in length

behavior/neurological

impaired contextual conditioning behavior ( J:178970 )

• display less freezing in response to context both 1 h and 24 h after training

impaired cued conditioning behavior ( J:178970 )

• display less freezing in response to the tone cue

• display less freezing in response to context both 1 h and 24 h after training

abnormal spatial learning ( J:178970 )

• slower acquisition of the task in a Morris water maze assay

cellular

delayed axon extension ( J:178970 )

• delay in outgrowth of retinal ganglion cell axons into the lateral geniculate nucleus such that the retinogeniculate projection area is reduced at P9 but catches up to wild-type by P90

Genotype
MGI:5307920

cx2

• Allelic Composition: Nrn1^tm1.2Ndiv/Nrn1^tm1.2Ndiv; Tg(Thy1-EGFP)SJrs/0
• Genetic Background: involves: C57BL/6 * CBA

nervous system

abnormal CNS synapse formation ( J:178970 )

• the percentage of dynamic events (spine gain or loss from neocortical neurons) that persist are significantly higher compared to wild-type mice

• the percentage of dynamic-persistent events that favor spine loss relative to dynamic-persistent events that favor spine gain is increased compared to wild-type controls suggesting a decrease in spine stabilization