Phenotypes associated with this allele

• Allele Symbol: Cacnb3^tm1Hssh
• Allele Name: targeted mutation 1, Hee-Sup Shin
• Allele ID: MGI:2180537
• Summary: 2 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Cacnb3^tm1Hssh/Cacnb3^tm1Hssh	involves: 129/Sv * 129S4/SvJae	MGI:3842781
hm2	Cacnb3^tm1Hssh/Cacnb3^tm1Hssh	involves: 129S4/SvJae * C57BL/6J	MGI:3843782

Genotype
MGI:3842781

hm1

• Allelic Composition: Cacnb3^tm1Hssh/Cacnb3^tm1Hssh
• Genetic Background: involves: 129/Sv * 129S4/SvJae

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

nervous system

nervous system phenotype ( J:50152 )

N • in brain areas where this gene is expressed, including the olfactory bulb, hippocampus, hebenula, and Purkinje cells, no morphological differences are seen in histological sections between mutant and control mice

N • in SCG neurons, the voltage dependence of calcium channel current activation is similar in mutant and controls

abnormal channel response ( J:50152 )

• in superior cervical ganglion (SCG) neurons from mutant mice, the density of calcium channel currents was characterized by successive applications of specific blockers; application of the L-type calcium channel blocker (nimodipine), the N-type calcium channel blocker (omega-conotoxin- GVIA), and the P/Q-type calcium channel blocker (omega-conotoxin-MVIIC) resulted in a reduction of the total current density in mutant and control neurons; the calculated difference representing the L-type current density shows a significant reduction in mutants compared to controls, whereas the current density for the N- and P/Q-type is similar in mutant and controls

• sympathetic neurons from the SCG display a wide range of N-type calcium channel density, with mutant neurons often displaying less than 30% of the total density

• total I_Ba magnitude using specific blockers suggests that two SCG neuronal populations exist that express high and low proportions of N-type calcium channel; those neurons that express high proportions of N-type calcium channel do not show significant changes in the density or proportion of any individual currents in mutants compared to controls upon treatment with specific blockers; however, those neurons that express low proportions of N-type calcium channel show significant reductions in the density and proportion of N-type currents upon treatment with specific blockers

vision/eye

vision/eye phenotype ( J:80080 )

N • both a- and b-waves appear normal in mutant mice

N • histological analysis indicates that retinal morphology is normal

Genotype
MGI:3843782

hm2

• Allelic Composition: Cacnb3^tm1Hssh/Cacnb3^tm1Hssh
• Genetic Background: involves: 129S4/SvJae * C57BL/6J

nervous system

nervous system phenotype ( J:136837 )

N • no gross abnormalities are seen in the hippocampus; mutant mice exhibit normal hippocampal divisions, including CA1, CA2, CA3 and dentate gyrus

N • in CA1 pyramidal neurons, no significant difference in calcium current density, voltage dependence and inactivating kinetics is seen between mutant and controls

N • in CA1 pyramidal neurons, intrinsic firing behavior and afterhyperpolarization currents is seen between mutant and control mice

N • at mutant hippocampal CA1-CA3 synapses, normal basal synaptic transmission is seen, as assayed by mESPCs and fEPSPs; in addition, no significant effect on short term plasticity (PPF) is seen.

abnormal optic tract morphology ( J:72711 )

abnormal sensory neuron innervation pattern ( J:72711 )

• refinement of the ipsilateral retinocollicular pathway and the contralateral retinogeniculate pathway of the retina to the superior colliculus and the dorsal lateral geniculate nucleus is abnormal in mutant mice

• at P15, the ipsilateral retinocollicular pathway was more robustly distributed than controls, with more extensive branching in the mediolateral axis of the superior colliculus and branches that extend into the dorsal superficial gray layer; at P21 and P28, refinement of the pathway occurs and is similar to adults by P28

• at P15, the projections of the contralateral retinogeniculate pathway completely fills the contralateral dorsal lateral geniculate nucleus (dLGN) unlike controls, with little or no sign of the ipsilateral projections in the dLGN; these differences were less apparent at P21 and P28

enhanced NMDA-mediated synaptic currents ( J:136837 )

enhanced long-term potentiation ( J:136837 )

• more robust potentiation is seen in mutant hippocampal slices at all tetanic stimulation levels tested; this increase is abolished in the presence of D-AP5, a specific NMDAR inhibitor, suggesting that the increase in potentiation is NMDAR-dependent LTP

behavior/neurological

enhanced contextual conditioning behavior ( J:136837 )

• in a contextual fear memory assay performed 24 hours after training, mutant mice display more fear-related behavior than controls, indicating an enhanced long term memory

• no difference between mutant and control mice is seen in a cued fear conditioning assay

abnormal discrimination learning ( J:136837 )

• in a social transmission of food preference task, both mutant and control mice show an equal preference for cued foods over non-cued foods at 1 hour after social interactions with demonstrator mice

• 24 hours after social interaction with demonstrator mice, mutant mice show significantly increased preference fo rcued food compared to controls

enhanced long-term object recognition memory ( J:136837 )

• both mutant and control mice show a similar amount of time exploring a novel object, and at a 1 hour retention interval, both mutant and control mice exhibit increased preference for a novel object over a familiar one

• at 24 hour retention interval, mutant mice show an increased preference compared to control mice for a novel object over a familiar one, suggesting enhanced long-term memory