Delayed synaptic transmission in Drosophila cacophonynull embryos

Area of Science:

• Neuroscience
• Molecular Biology
• Developmental Biology

Background:

• Fast synaptic transmission relies on calcium (Ca(2+)) influx through voltage-gated channels.
• The Drosophila cacophony (cac) gene encodes an N-type Ca(2+) channel crucial for this process.

Purpose of the Study:

• To determine if the cac Ca(2+) channel is the sole mediator of fast synaptic transmission.
• To investigate the role of other Ca(2+) channels in synaptic transmission in Drosophila.

Main Methods:

• Utilized cac(null) mutant Drosophila embryos due to the lethality of the mutation.
• Examined neuromuscular junction synaptic transmission under varying external calcium concentrations ([Ca(2+)](e)).
• Assessed the effects of Plectreurys toxin II (PLTXII) and La(3+) on synaptic events.

Main Results:

• cac(null) embryos lacked fast synchronous synaptic transmission but exhibited infrequent delayed events dependent on [Ca(2+)](e).
• Wild-type cac gene introduction restored fast transmission.
• Delayed events were reduced by PLTXII, suggesting involvement of non-cac Ca(2+) channels, but unaffected by La(3+).
• Reduced miniature synaptic currents and hypertonicity response in cac(null) embryos indicated fewer release-ready vesicles.

Conclusions:

• The cac Ca(2+) channel is indispensable for normal fast synaptic transmission.
• A distinct, PLTXII-sensitive, non-cac Ca(2+) channel contributes to delayed synaptic release in Drosophila embryos.