Phenotypes Associated with This Genotype

Genotype
MGI:3696550

• Allelic Composition: Syt2^tm1Sud/Syt2^tm1Sud
• Genetic Background: B6.129-Syt2^tm1Sud

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

mortality/aging

lethality at weaning, complete penetrance ( J:117050 )

• knockouts start to die at P19; all are dead by P24

growth/size/body

decreased body weight ( J:117050 )

postnatal growth retardation ( J:117050 )

• mutants stop growing in the second week after birth

behavior/neurological

abnormal motor capabilities/coordination/movement ( J:117050 )

• mutants show severe motor dysfunction in second postnatal week

abnormal locomotor behavior ( J:117050 )

• by P15, mice are almost unable to move

nervous system

abnormal CNS synaptic transmission ( J:117050 )

abnormal inhibitory postsynaptic currents ( J:117050 )

• synaptic charge transfer shows a significantly slower time course in striatal neurons than in control neurons

• mean decay time constants for fast and slow constituents are significantly increased compared to control; fast decay constant is increased by ~20%, while slow decay constant is increased by >100%

abnormal miniature endplate potential ( J:117050 )

• in diaphragm muscle, miniature end plate potentials (mEPPs; spontaneous release events) at the neuromuscular junctions (NMJs) show a 10-fold increase in frequency compared to diaphragms of wild-type littermate

abnormal neurotransmitter secretion ( J:117050 )

• release is mostly desynchronized in a subpopulation of striatal neurons

• mutant synapses show desynchronization of evoked vesicle release during repetitive stimulation even at frequencies of 10 Hz

• 10-fold increase in delayed release in NMJs is seen compared to controls

decreased neurotransmitter release ( J:117050 )

• in phrenic nerve, amplitude and quantal content of end plate potentials, EPP) are decreased ~2-fold compared to control; rate of increase of EPPs is 3-fold lower compared to controls at NMJs

enhanced paired-pulse facilitation ( J:117050 )

• large degree of PPF is observed compared to control neurons

• at 10 and 20 Hz stimulation, NMJs exhibit continued facilitation without depression whereas initial facilitation followed by moderate depression is observed in controls

• initial EPP amplitude in 2-fold lower in mutants by facilitation increases to steady state levels similar to control

• NMJs exhibit a failure rate at 10 and 20 Hz of 6 and 1.5% respectively, whereas controls NMJs show no failures