behavior/neurological
• in non-rotating rod test, equilibrium times of mutants are lower than controls in all three trials
(J:82371)
• mutants fall often, generally after rearing up or grooming, during the period of hyperactivity in response to stimulus
(J:82709)
|
• mutants exhibit poor performance in a motor training test with a rotarod, however they are able to improve their performance over time
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• body is flattened to the ground while walking
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• tapping of the hindpaws; phenotype is much more severe than in Grid2ho-4J mice
• mutants exhibit increased stumbling frequency in a motor coordination test
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abnormal gait
(
J:82709
)
• jumpy, hopping gait; hindlimbs are alternately raised very rapidly
• the angle of the feet is more open in mutants than controls
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• mutants exhibit a reduction in the length of stride by at least half due to mutants moving the same hind foot forward very rapidly, several times in succession, by a very small distance each time, advancing the contralateral foot
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retropulsion
(
J:82709
)
• adults often walk backwards
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• upon pressure on the tail, mutants back up or turn around and vocalize instead of running away as do controls
• when flanks are pressed, mutants leap forward powerfully
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limb grasping
(
J:82709
)
• some mice when lifted by the tail, pull their hind feet together up to the belly
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nervous system
• Purkinje cells have ectopic spines devoid of presynaptic innervations
(J:82371)
|
• occurrence of long ectopic and sometimes branching spines emanating from the proximal dendritic compartment of Purkinje cells
(J:82371)
• ectopic spines are frequently innervated by parallel fiber varicosities
(J:82371)
• presence of non-innervated (naked) spines in the vicinity of Purkinje cell dendrites
(J:82371)
|
• occasional occurrence of pyknotic nuclei in the granule cell layer
(J:82371)
• slight atrophy of the granule layer
(J:82709)
|
• slight atrophy of the molecular layer
• the molecular layer exhibits atypical axon terminals, with hypertrophy of the smooth endoplasmic reticulum
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• cerebellum is slightly reduced in size
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• slight atrophy of the granule and molecular layers
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• although most Purkinje cells are innervated by a single climbing fiber, about 19-20% of cells show innervation by more than one climbing fiber
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• mismatching between the length of the presynaptic active zones, in parallel fiber varicosities, and the postsynaptic differentiations in Purkinje cell dendritic spines
(J:82371)
• some somatodendritic synapses occur between the perikarya of basket or stellate cells and Purkinje cell dendritic spines or small dendritic profiles
(J:82371)
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