Bichromatic exon-reporters reveal voltage-gated Ca -channel splice-isoform diversity across neurons .

Every neuron contains the same genomic information but its complement of proteins is the product of countless neuron-specific steps including pre-mRNA splicing. Despite advances in RNA sequencing techniques, pre-mRNA splicing biases that favor one isoform over another are largely inscrutable in live neurons . Here, in , we developed bichromatic fluorescent reporters to investigate alternate splicing of - a gene that codes the pore-forming α -subunit of the primary neuronal voltage-gated Ca channel (VGCC).

Physiologic and Nanoscale Distinctions Define Glutamatergic Synapses in Tonic vs Phasic Neurons.

Neurons exhibit a striking degree of functional diversity, each one tuned to the needs of the circuitry in which it is embedded. A fundamental functional dichotomy occurs in activity patterns, with some neurons firing at a relatively constant "tonic" rate, while others fire in bursts, a "phasic" pattern. Synapses formed by tonic versus phasic neurons are also functionally differentiated, yet the bases of their distinctive properties remain enigmatic.

Computational modeling predicts ephemeral acidic microdomains in the glutamatergic synaptic cleft.

At chemical synapses, synaptic vesicles release their acidic contents into the cleft, leading to the expectation that the cleft should acidify. However, fluorescent pH probes targeted to the cleft of conventional glutamatergic synapses in both fruit flies and mice reveal cleft alkalinization rather than acidification. Here, using a reaction-diffusion scheme, we modeled pH dynamics at the Drosophila neuromuscular junction as glutamate, ATP, and protons (H) were released into the cleft.

Neuronal Glutamatergic Synaptic Clefts Alkalinize Rather Than Acidify during Neurotransmission.

The dogma that the synaptic cleft acidifies during neurotransmission is based on the corelease of neurotransmitters and protons from synaptic vesicles, and is supported by direct data from sensory ribbon-type synapses. However, it is unclear whether acidification occurs at non-ribbon-type synapses. Here we used genetically encoded fluorescent pH indicators to examine cleft pH at conventional neuronal synapses.