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General Information
Symbol
Dmel\Syt4BA1
Species
D. melanogaster
Name
FlyBase ID
FBal0191284
Feature type
allele
Associated gene
Associated Insertion(s)
Carried in Construct
Nature of the Allele
Mutations Mapped to the Genome
 
Type
Location
Additional Notes
References
Associated Sequence Data
DNA sequence
Protein sequence
 
 
Cytology
Nature of the lesion
Statement
Reference

Imprecise excision of P{EPgy2}EY09259, found 100bp 5' of the Syt4 transcription start site.

SytIVBA1 is an intragenic deletion that removes SytIV immunoreactivity.

Expression Data
Reporter Expression
Additional Information
Statement
Reference
 
Marker for
Reflects expression of
Reporter construct used in assay
Human Disease Associations
Disease Ontology (DO) Annotations
Models Based on Experimental Evidence ( 0 )
Disease
Evidence
References
Modifiers Based on Experimental Evidence ( 0 )
Disease
Interaction
References
Comments on Models/Modifiers Based on Experimental Evidence ( 0 )
 
Phenotypic Data
Phenotypic Class
Phenotype Manifest In
Detailed Description
Statement
Reference

Syt4BA1/Syt4BA1 third instar larvae have significantly fewer synaptic boutons and a significantly reduced ability to grow new "ghost" boutons under high K[+] stimulation at the neuromuscular junction compared to controls. Syt4BA1/+ heterozygotes have similar numbers of boutons as controls.

Syt4BA1 mutant third instar larvae do not display any synaptic overgrowth (assessed by the number of boutons) at neuromuscular junctions compared to controls. Syt4BA1 mutants do not show the activity-dependent enhancement of spontaneous release that is normally observed in wild-type and in contrast to controls their frequency of minis prior and post high-frequency stimulation remains the same.

Syt4BA1 mutants reduce synaptic growth at the neuromuscular junction with a 24% decrease in varicosity number compared to controls. Active zone number appears to parallel bouton number.

Syt4BA1/Df(3R)rn16 mutants reduce synaptic growth at the neuromuscular junction with a 28% decrease in varicosity number compared to controls. Active zone number appears to parallel bouton number.

Homozygous Syt4BA1 mutants exhibit reduced spontaneous neurotransmitter release in the absence of nerve stimulation (at 0.5mM Ca[2+] concentration). These changes in evoked responses are not observed in 2.0mM extracellular Ca[2+] concentration, suggesting that alterations in release probability or vesicle pool size may compensate for the altered number of release sites. The fast component of synaptic depression release during initial stimulation is unchanged. However, a lower depletion of synaptic vesicles and a higher baseline-evoked response during steady-state stimulation is observed in Syt4BA1 mutants.

Syt4BA1 mutants fail to show increased spontaneous release after stimulation.

Althoygh control larvae show a 33% increase in bouton number when reared at 31[o]c compared with 25[o]C, Syt4BA1 mutants display no statistically significant increase in bouton number at 31[o]C.

There are no statistical differences in evoked excitatory junctional potential amplitudes between Syt4BA1 animals and controls, even at low 0.1 mM extracellular Ca[2+] concentrations. Also, the amount of facilitation at all interpulse intervals tested was statistically the same as controls, indicating paired-pulse facilitation is unaffected.

High-frequency-stimulation-induced miniature release (HFMR) is eliminated in the neuromuscular junctions of SytIVBA1 animals, in contrast to controls. The presynaptic morphology of motor terminals is abnormal at the mutant neuromuscular junction; the motor terminals fail to constrict into normal synaptic varicosities and maintain a flat, less varicose appearance.

External Data
Interactions
Show genetic interaction network for Enhancers & Suppressors
Phenotypic Class
Enhanced by
Statement
Reference
Suppressed by
NOT Enhancer of
Statement
Reference
Suppressor of
Statement
Reference

Syt4BA1 is a suppressor of neuroanatomy defective | temperature conditional phenotype of parats1

Syt4BA1 is a suppressor of neuroanatomy defective | temperature conditional phenotype of sei1

NOT Suppressor of
Other
Phenotype Manifest In
Enhanced by
Statement
Reference

Syt4BA1 has NMJ bouton | third instar larval stage phenotype, enhanceable by Syx4[+]/Syx473

Suppressed by
Statement
Reference

Syt4BA1 has neuromuscular junction | temperature conditional phenotype, suppressible by parats1

Syt4BA1 has NMJ bouton | temperature conditional phenotype, suppressible by parats1

NOT Enhancer of
Statement
Reference

Syt4[+]/Syt4BA1 is a non-enhancer of NMJ bouton | third instar larval stage phenotype of Syx473

Suppressor of
Statement
Reference

Syt4BA1 is a suppressor of neuromuscular junction | temperature conditional phenotype of parats1

Syt4BA1 is a suppressor of neuromuscular junction | temperature conditional phenotype of sei1

Syt4BA1 is a suppressor of NMJ bouton | temperature conditional phenotype of sei1

Other
Additional Comments
Genetic Interactions
Statement
Reference

Syx473/+ or Syt4BA1/+ third instar larvae do not show significant differences in bouton number at the neuromuscular junction compared to controls, but Syx473/+;Syt4BA1//+ double heterozygotes have significantly fewer boutons compared to controls or either single heterozygote. Syx473/Y;Syt4BA1/Syt4BA1 mutants die during the second instar larval stage. Syx473/+ significantly enhances the reduction in bouton number at the NMJ of Syt4BA1/Syt4BA1 third instar larvae. Syt4BA1/+ does not significantly enhance the reduction in bouton number at the NMJ of Syx473/Y hemizygous third instar larvae.

Syt4BA1/+;Df(3R)Nlg1ex3.1/+ larvae have a significantly reduced ability to grow new "ghost" boutons under high K[+] stimulation at the neuromuscular junction compared to controls and single heterozygotes (though double heterozygotes do not show significant changes in the number of boutons under normal conditions compared to controls).

The synaptic overgrowth (increased number of boutons) at neuromuscular junctions observed in third instar larvae mutant for either cpxSH1 or Syx1A3-69 can be suppressed by homozygosity of Syt4BA1 (which on its own does not lead to any elevation in synaptic growth) but this fails to suppress the increased frequency of mini excitatory junction potentials.

sei1 ; Syt4BA1 double mutants exhibit no significant change in bouton number between 25[o]c and 31[o]C.

Synaptic outgrowth induced by expression of Syt4wt.Scer\UAS under the control of Scer\GAL4Mhc.PW is dramatically reduced in a parats1 background when animals are reared at 31[o]C compared with 25[o]C.

Like Syt1AD4/Syt1N13 mutants alone, Syt1AD4/Syt1N13, Syt4BA1 double mutants display robust asynchronous release. Paired-pulse facilitation remains intact in the double mutants, with enhanced facilitation as observed in Syt1AD4/Syt1N13 mutants alone. Also similar to Syt1AD4/Syt1N13 mutants alone, the release observed during paired-pulse stimulation in the double mutants remains asynchronous compared to wild type controls.

Xenogenetic Interactions
Statement
Reference

Expression of Mmus\PkacamC.Scer\UAS under the control of Scer\GAL4D42 restores the normal constricted varicosities at the motor terminals of the SytIVBA1 neuromuscular junction.

Complementation and Rescue Data
Comments

Syt4GFP-2M or expression of Syt4Scer\UAS.T:Avic\GFP-pHluorinE driven by Scer\GAL4how-24B rescues bouton number at the neuromuscular junction of Syt4BA1/Syt4BA1 third instar larvae; Syt4Scer\UAS.T:Avic\GFP-pHluorinE driven by Scer\GAL4how-24B also rescues ability of mutants to grow new "ghost" boutons under high K[+] stimulation.

Expression of Syt4wt.Scer\UAS post-synaptically under the control of Scer\GAL4Mhc.PW rescues the Syt4BA1/Df(3R)rn16 synaptic growth defect.

Images (0)
Mutant
Wild-type
Stocks (0)
Notes on Origin
Discoverer
External Crossreferences and Linkouts ( 0 )
Synonyms and Secondary IDs (4)
Reported As
Name Synonyms
Secondary FlyBase IDs
    References (7)