Cellular NeuroscienceDifferences in Ca2+ regulation for high-output Is and low-output Ib motor terminals in Drosophila larvae
Section snippets
Loading the terminals with OGB-1
All experiments were performed on the terminals innervating MFs 6 and 7 (MF 6/7) and those innervating MF 4 in segment 3 of Drosophila (Canton S) wandering 3rd-instar, female larvae. To measure changes in [Ca2+]i, we used the single-wavelength Ca2+ indicator, Oregon Green 488 BAPTA-1 (OGB-1) coupled to 10,000 MW dextrans; its dissociation constant (Kd) was 1180 nM as reported by Molecular Probes (Invitrogen, Carlsbad, CA, USA). The technique for loading the indicator was developed by Macleod et
Is and Ib terminals show differences in Ca2+ transients
To measure Ca2+ transients, the terminals were loaded with a dextran conjugate of OGB-1. The OGB-1 reported changes in cytosolic [Ca2+] since the dextran prevented compartmentalization of the OGB-1. We measured Ca2+ transients produced by single APs and 10 Hz trains of APs in the two pairs of Is and Ib terminals innervating MF 4 and 6/7. These four terminals are all generated by different axons (Lnenicka and Keshishian 2000, Hoang and Chiba 2001). We have found that MF 4 occasionally has two Ib
Is–Ib differences in Ca2+ transients
We measured ΔF/F by capturing images of the terminals during nerve stimulation and found that the Ca2+ transients were larger for Is than Ib boutons. The ΔF/FAP peak and ΔF/Ftrain plateau were greater at Is boutons than at Ib boutons for both MFs 4 and 6/7. Measurements of ΔF/F also showed differences in the τdecay for Is and Ib boutons. The ΔF/FAP τdecay was longer for Is boutons than for Ib boutons on MF 4, but not on MF 6/7. For AP trains, the τdecay was longer for Is boutons than for Ib
Acknowledgments
Supported by NSF grant IOB 0543835 (G.A.L.).
References (36)
- et al.
Short-term and long-term plasticity and physiological differentiation of crustacean motor synapses
Int Rev Neurobiol
(1986) - et al.
Mechanisms underlying the rapid induction and sustained expression of synaptic homeostasis
Neuron
(2006) - et al.
Calcium dynamics associated with a single action potential in a CNS presynaptic terminal
Biophys J
(1997) - et al.
Single-cell analysis of Drosophila larval neuromuscular synapses
Dev Biol
(2001) The use of fura-2 for estimating Ca buffers and Ca fluxes
Neuropharmacology
(1995)- et al.
Localization and functional significance of the Na+/Ca2+ exchanger in presynaptic boutons of hippocampal cells in culture
Neuron
(1995) Transmitter release at the neuromuscular junction
Int Rev Neurobiol
(2006)- et al.
Bruchpilot, a protein with homology to ELKS/CAST, is required for structural integrity and function of synaptic active zones in Drosophila
Neuron
(2006) Exocytosis: a molecular and physiological perspective
Neuron
(1996)- et al.
Differential ultrastructure of synaptic terminals on ventral longitudinal abdominal muscles in Drosophila larvae
J Neurobiol
(1993)
Strength of synaptic transmission at neuromuscular junctions of crustaceans and insects in relation to calcium entry
Invert Neurosci
Standard mathematical tables and formulae
Activity-dependent plasticity of calcium clearance from crayfish motor axons
J Neurophysiol
Heterogeneity in synaptic transmission along a Drosophila larval motor axon
Nat Neurosci
Calcium dynamics, buffering, and buffer saturation in the boutons of dentate granule-cell axons in the hilus
J Neurosci
Antibodies to horseradish peroxidase as specific neuronal markers in Drosophila and in grasshopper embryos
Proc Natl Acad Sci U S A
Imaging of calcium in Drosophila larval motor nerve terminals
J Neurophysiol
The drosophila neuromuscular junction: a model system for studying synaptic development and function
Annu Rev Neurosci
Cited by (19)
Crayfish and Drosophila NMJs
2020, Neuroscience LettersCitation Excerpt :Consistent with the phasic-tonic differentiation, there were more mitochondria in Ib boutons than in Is boutons [12] and transmitter release per active zone was about 4 times greater for Is boutons than Ib boutons [59]. The differences in transmitter release did not appear to be due to differences in Ca2+ influx per active zone [60]; it is not known whether Is and Ib boutons show differences in their Ca2+ sensitivity of transmitter release as seen for crayfish phasic and tonic synapses. Chronic stimulation of a crayfish phasic axon transformed the NMJ to become more tonic-like suggesting that activity played a role in the normal differentiation of the NMJ.
Neto-α Controls Synapse Organization and Homeostasis at the Drosophila Neuromuscular Junction
2020, Cell ReportsCitation Excerpt :Finally, the Ca2+ signals evoked by 10 and 20 Hz stimulus trains were no different in neto-αnull (10 Hz, data not shown; Ib, p = 0.63; Is, p = 0.93) (20 Hz; Ib, p = 0.37; Is, p = 0.40) (Figure 6E). Although the data shown here are sufficiently sensitive to reveal the differences in Ca2+ entry known to exist between type Ib and type Is terminals (He et al., 2009; Lu et al., 2016), they reveal no deficit in Ca2+ entry in neto-αnull terminals. Thus, neto-αnull neurotransmission deficits are most likely the result of deficits in the release apparatus downstream of Ca2+ entry.
The functional organization of motor nerve terminals
2015, Progress in NeurobiologyCitation Excerpt :In practice, this approach depends on a favorable nerve terminal architecture. It has so far been possible to detect activity-dependent Ca2+ transients in motor nerve terminals of Drosophila (He et al., 2009a,b; Macleod et al., 2002), crayfish (Delaney et al., 1989; He et al., 2009b; Lnenicka et al., 2006; Millar et al., 2005; Msghina et al., 1999; Tank et al., 1995), frogs (DiGregorio et al., 1999; Luo et al., 2011; Wachman et al., 2004) and lizards (David et al., 1997). ( The geometric complexity of nematode and mammalian NMJs has so far prevented similar studies in these animals).
The fragile X mental retardation protein developmentally regulates the strength and fidelity of calcium signaling in Drosophila mushroom body neurons
2011, Neurobiology of DiseaseCitation Excerpt :In both Drosophila and mammals, FMRP functions in activity-dependent mechanisms, and membrane depolarization has been used repeatedly to identify FMRP-dependent defects (Antar et al., 2004; Bear et al., 2004; Muddashetty et al., 2007; Nosyreva and Huber, 2006; Repicky and Broadie, 2009; Tessier and Broadie, 2008). Since external calcium influx is a key signaling event, we first examined depolarization-dependent calcium transients in control and dfmr1 null MBs from intact brains (Fiala and Spall, 2003; He et al., 2009; Kuromi et al., 2004; Reiff et al., 2005; Wang et al., 2004b; Yu et al., 2003, 2006). To confirm specificity to the dfmr1 locus, we utilized two independently generated alleles of dfmr1 (dfmr150M and dfmr13) for all experiments.
Physiologic and Nanoscale Distinctions Define Glutamatergic Synapses in Tonic vs Phasic Neurons
2023, Journal of Neuroscience