Phenotypes associated with this allele

• Allele Symbol: Unc13b^tm2Bros
• Allele Name: targeted mutation 2, Nils Brose
• Allele ID: MGI:2449706
• Summary: 4 genotypes

Jump to	Allelic Composition	Genetic Background	Genotype ID
hm1	Unc13b^tm2Bros/Unc13b^tm2Bros	Not Specified	MGI:2654055
cx2	Unc13a^tm1Bros/Unc13a^tm1Bros Unc13b^tm2Bros/Unc13b^tm2Bros	involves: 129	MGI:2654056
cx3	Unc13a^tm2Bros/Unc13a^+ Unc13b^tm2Bros/Unc13b^tm2Bros	Not Specified	MGI:3718430
cx4	Unc13a^tm2Bros/Unc13a^tm2Bros Unc13b^tm2Bros/Unc13b^tm2Bros	Not Specified	MGI:3718432

Genotype
MGI:2654055

hm1

• Allelic Composition: Unc13b^tm2Bros/Unc13b^tm2Bros
• Genetic Background: Not Specified

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

vision/eye

vision/eye phenotype ( J:185276 )

N • mice exhibit normal photoreceptor ribbon synaptic transmission

abnormal eye electrophysiology ( J:185276 )

• in peak-to-peak amplitudes and frequency of oscillatory potentials is slightly reduced compared to in wild-type mice

abnormal cone electrophysiology ( J:185276 )

• b-wave amplitude is very slightly reduced in photopic conditions

abnormal rod electrophysiology ( J:185276 )

• b-wave amplitude is slightly reduced in scotopic conditions

• however, b-wave implicit time is normal

nervous system

nervous system phenotype ( J:77339 )

N • normal cytoarchitecture and ultrastructure of the CNS

sporadic seizures ( J:77339 )

• observed in mice older than 12 months old

abnormal synapse morphology ( J:185276 )

• photoreceptor ribbon synapses contain slightly more docked synaptic vesicles than in wild-type mice

behavior/neurological

sporadic seizures ( J:77339 )

• observed in mice older than 12 months old

Genotype
MGI:2654056

cx2

• Allelic Composition: Unc13a^tm1Bros/Unc13a^tm1Bros; Unc13b^tm2Bros/Unc13b^tm2Bros
• Genetic Background: involves: 129

mortality/aging

neonatal lethality, complete penetrance ( J:77339 )

• all mutants born alive, die within 1 hour after birth

nervous system

abnormal synapse morphology ( J:77339 )

• length of active zones is larger in synapses, thus the number of docked vesicles per um active zone is lower, however mutants form normal numbers of synapses

• cultured neurons are unable to exocytose and lack calcium-triggered endocytotic activity

abnormal synaptic vesicle number ( J:77339 )

• complete loss of fusion competent vesicles

abnormal neuron physiology ( J:167753 )

• flash-response is abolished in neurons compared with control mice

abnormal synaptic transmission ( J:77339 )

• spontaneous, action potential evoked, and hypertonically evoked vesicular release (synaptic transmission) are abolished

abnormal excitatory postsynaptic currents ( J:167753 )

• excitatory postsynaptic current induced by calcium uncaging is abolished compared to in control mice

Genotype
MGI:3718430

cx3

• Allelic Composition: Unc13a^tm2Bros/Unc13a⁺; Unc13b^tm2Bros/Unc13b^tm2Bros
• Genetic Background: Not Specified

nervous system

abnormal synaptic vesicle morphology ( J:117827 )

• spontaneous release rates are intermediate and are increased by PDBu (4beta-phorbol-12,13-dibutyrate) treatment

abnormal synaptic vesicle number ( J:117827 )

• the number of fusion-competent vesicles is reduced to 2763+/-305 vesicles compared to 4109+/-722 vesicles in wild-type mice

abnormal excitatory postsynaptic currents ( J:117827 )

• at 10Hz action potential trains, excitatory postsynaptic current depression is enhanced relative to that in wild-type cells but not as much as in homozygotes and further enhanced by treatment with PDBu (4beta-phorbol-12,13-dibutyrate)

Genotype
MGI:3718432

cx4

• Allelic Composition: Unc13a^tm2Bros/Unc13a^tm2Bros; Unc13b^tm2Bros/Unc13b^tm2Bros
• Genetic Background: Not Specified

nervous system

abnormal synaptic vesicle morphology ( J:117827 )

• the rate of vesicle release is doubled compared to in wild-type cells for all doses tested

• spontaneous release rates are increased and are not effected by PDBu (4beta-phorbol-12,13-dibutyrate) treatment

• the probability of vesicle release is increased relative to in wild-type cells

abnormal synaptic vesicle number ( J:117827 )

• the number of fusion-competent vesicles is reduced to 2299+/-300 vesicles compared to 4109+/-722 vesicles in wild-type mice

• following stimulation with 250mM sucrose, the number of vesicles released is greater (2000+/-460 vesicles) than in wild-type cells (1100+/-300 vesicles)

abnormal excitatory postsynaptic currents ( J:117827 )

• at 10Hz action potential trains, excitatory postsynaptic current depression is enhanced relative to that in wild-type cells and is further enhanced by treatment with PDBu by (4beta-phorbol-12,13-dibutyrate)

abnormal miniature excitatory postsynaptic currents ( J:117827 )

• the absolute frequency of miniature excitory postsynaptic currents is more than doubled that in wild-type cells but similar to that in phorbol ester-treated wild-type cells

abnormal long-term depression ( J:117827 )

• long term potential is enhanced relative to in wild-type cells but similar to in that in wild-type cells treated with PDBu (4beta-phorbol-12,13-dibutyrate)