Biology subjects

Deitcher, D. L.

Publications and source records attributed to Deitcher, D. L..

6 recordsLinked to original sources

bioRxiv2026

Adult Clock Neuron Somatic Neuropeptide Release and Cytonemes Regulate Sleep

Drosophila s-LNv clock neurons promote nighttime sleep by releasing the neuropeptide sNPF to activate sNPF receptors (sNPF-Rs) on l-LNv clock neurons. Behavior is controlled by synaptic transmission, but s-LNv and l-LNv neurons are not connected directly by chemical synapses. To investigate the basis of sNPF/sNPF-R communication between LNv neurons, the spread of sNPF was imaged in the adult brain. We report the daily midmorning burst of sNPF released from s-LNv terminals does not reach l-LNv neurons or s-LNv somata. Instead, sNPF released by the s-LNv soma late at night in response to sleep-promoting IP3 signaling reaches l-LNv somata, but not their terminals. In addition to communication by neuropeptide diffusion, analysis of fly connectomes revealed that adult s-LNv and l-LNv neurons form non-synaptic direct contacts mediated by cytonemes. Remarkably, genetically perturbing LNv neuron cytonemes alters sleep latency, but not nighttime sleep, the target of somatic sNPF release, or circadian behavior, which depends on PDF neuropeptide released by LNv terminals. Therefore, three distinct aspects of adult rhythmic behavior are produced by terminals, the soma and cytonemes, with the latter possibly acting via contacts that are not currently annotated in the connectome.

neuroscience↗

bioRxiv2025

Circadian Capture of Dense-Core Vesicles Rhythmically Boosts Presynaptic Neuropeptide Content in a Clock Neuron

Neuropeptide release by Drosophila sLNv clock neurons controls circadian behaviors and sleep. Remarkably, neuropeptide content in sLNv terminals is rhythmic with late-night accumulation occurring while the axon arbor is expanding in preparation for midmorning synaptic exocytosis of neuropeptide-containing dense-core vesicles (DCVs). Past studies showed increased synaptic neuropeptide content can be produced by delivery of more neuropeptide to terminals or activity-dependent capture of circulating DCVs. To distinguish between these mechanisms, neuropeptide-containing DCVs were imaged in the living brain explant. First, post-exocytosis DCV axonal transport and synaptic neuropeptide accumulation following retrograde transport inhibition show that sLNv DCVs circulate. Furthermore, anterograde transport to terminals is constant throughout the day demonstrating there is no increase in DCV delivery. Rather, capture of circulating DCVs produces the daily boost in terminal neuropeptide content. Remarkably, this capture occurs before the daily increase in Ca2+ spike activity and is also independent of concurrent IP3 signaling and daily axon arbor expansion. Finally, a per clock gene mutation inhibits rhythmic DCV capture. Thus, rather than participating in axonal plasticity or responding to Ca2+ signaling, capture of circulating DCVs in sLNv presynapses is increased by the molecular clock in anticipation of activity-induced release hours later.

cell biology↗

bioRxiv2025

Automated behavior classification of julius seizure mutants in Drosophila reveals stereotyped seizure stages with genotype specificity

Bang-sensitive (BS) Drosophila mutants exhibit a stereotyped pattern of seizure behavior after mechanical disturbances. We previously identified mutations in the julius seizure (jus) gene, formerly CG14509, can induce BS seizures. However, the behavioral manifestations of the seizure phenotype of the various jus mutants have not been fully characterized. Here, we developed a machine learning pipeline featuring LASC (Long short-term memory and Attention mechanism for Sequence Classification) for automatic phenotyping of jus mutant videos. LASC achieves 90% classification accuracy in distinguishing five phases: paralysis (P), tonic seizure (T), spasm (S), clonic seizure (C), and recovery (R). Applying the trained LASC model to multiple jus lines showed they use a common repertoire of seizure stages and followed the general P[->]T[->]S[->]C[->]R progression, but each genotype exhibited unique patterns of stage duration and transition probabilities. Remarkably, stage usage patterns are distinct among the mutant genotypes. These findings establish that while all jus mutants adhere to stereotyped behavioral rules, each allele generates a distinct signature in stage usage. This work demonstrates how advanced behavioral quantification can reveal previously hidden relationships between gene mutation and complex motor outputs. More broadly, the complete pipeline presented here can pave the way for high-throughput, automated drug screening for epilepsy.

neuroscience↗

bioRxiv2023

A Complex Containing the Na+/K+ ATPase Regulates Epileptogenesis in Drosophilamelanogaster

Epileptogenesis, the process through which the brain becomes seizure-prone, is not well understood. Previous work identified a novel gene in Drosophila, julius seizure (jus), that when mutated or developmentally knocked down, leads to epilepsy in adult Drosophila, providing a useful model for dissecting epileptogenesis. Here we report that when a GFP-tagged version of Jus was used as bait in a co-immunoprecipitation (co-IP) assay, a complex of 23 associated proteins was identified that included ATPalpha and Nervana 3, two subunits of the Na+/K+ ATPase. RNAi-mediated knockdown of ATPalpha, Nervana 3, or any of 8 additional complex proteins enhanced seizure susceptibility. The critical period of Jus expression in epileptogenesis was further defined, occurring between pupal stages P4-7; remarkably, the jus seizure phenotype could be rescued by increasing neural activity of jus-expressing neurons during these mid-pupal stages, suggesting that altered neural activity in these neurons may contribute to the seizure phenotype. Our data support a model that, in wild type flies, a protein complex containing Na+/K+ ATPase and Jus prevents epileptogenesis, possibly by regulating neural activity.

neuroscience↗

bioRxiv2022

Release of large synaptic DCV proteins is triggered by Ca2+-independent Rugose-localized complexin phosphorylation

Neuronal dense-core vesicles (DCVs) contain neuropeptides and much larger proteins that affect synaptic growth and plasticity. Rather than using full collapse exocytosis that is common in endocrine cells, DCVs at a native intact synapse, the Drosophila neuromuscular junction, release their contents via fusion pores formed by kiss and run exocytosis. Here fluorogen activating protein (FAP) imaging reveals the permeability range of synaptic DCV fusion pores and then shows that this constraint is circumvented by cAMP-induced extra fusions with dilating pores that result in DCV emptying. These Ca2+-independent full fusions require PKA-R2, a PKA phosphorylation site on the fusion clamp protein complexin and the acute presynaptic function of Rugose/Neurobeachin, a PKA-R2 anchor implicated in learning and autism. Therefore, localized Ca2+-independent cAMP signaling opens dilating fusion pores to release large cargo proteins that cannot pass through the narrower fusion pores that normally dominate spontaneous and Ca2+-evoked synaptic protein release. Hence, two independent exocytosis triggers (Ca2+ and cAMP) vary the composition of released proteins at the synapse by differentially adjusting DCV fusion pores.

neuroscience↗

bioRxiv2020

Independently Regulated Multi-compartment Neuropeptide Release from a Clock Neuron Controls Circadian Behavior

Neuropeptides control rhythmic behaviors, but the timing and location of their release within circuits is unknown. Here imaging in the brain shows that synaptic neuropeptide release by Drosophila clock neurons is diurnal, peaking at times of day that were not anticipated by prior electrical and Ca2+ data. Furthermore, hours before peak synaptic neuropeptide release, neuropeptide release occurs at the soma, a neuronal compartment that has not been implicated in peptidergic transmission. The timing disparity between release at the soma and terminals results from independent and compartmentalized mechanisms for daily rhythmic release: consistent with conventional electrical activity-triggered synaptic transmission, terminals require Ca2+ influx, while somatic neuropeptide release is triggered by the biochemical signal IP3. Upon disrupting the somatic mechanism, the rhythm of terminal release and locomotor activity period are unaffected, but the number of flies with rhythmic behavior and sleep-wake balance are reduced. These results support the conclusion that somatic neuropeptide release controls specific features of clock neuron dependent behaviors. Thus, compartment specific mechanisms within individual clock neurons produce temporally and spatially partitioned neuropeptide release to expand the peptidergic connectome underlying daily rhythmic behaviors. Significance StatementIt is believed that electrical activity simultaneously stimulates widespread release sites in single neurons to elicit neuropeptide dependent behaviors. However, optically detecting neuropeptide release in the intact brain shows that clock neurons release neuropeptides from different sites at different times of the day. This is possible because one neuronal compartment, the soma, uses biochemical signaling instead of electrical activity to evoke release. Disrupting somatic release affects specific features of circadian locomotor activity and sleep. Thus, neuropeptide release is elicited by independent triggers from distinct parts of clock neurons to engage different regions of behavior regulating circuitry. This strategy for expanding the connectome may be used for other neuropeptide dependent behaviors, such as feeding and pain perception.

neuroscience↗