scholarly journals Cell-selective modulation of the Drosophila neuromuscular system by a neuropeptide

2015 ◽  
Vol 113 (5) ◽  
pp. 1631-1643 ◽  
Author(s):  
Kiel G. Ormerod ◽  
Jacob L. Krans ◽  
A. Joffre Mercier
Keyword(s):  
Motor Neurons ◽  
Input Resistance ◽  
Muscle Cells ◽  
Fruit Fly ◽  
Physiological Properties ◽  
Selective Modulation ◽  
Specific Manner ◽  
A Cell ◽  
Evoked Contractions

Neuropeptides can modulate physiological properties of neurons in a cell-specific manner. The present work examines whether a neuropeptide can also modulate muscle tissue in a cell-specific manner using identified muscle cells in third-instar larvae of fruit flies. DPKQDFMRFa, a modulatory peptide in the fruit fly Drosophila melanogaster, has been shown to enhance transmitter release from motor neurons and to elicit contractions by a direct effect on muscle cells. We report that DPKQDFMRFa causes a nifedipine-sensitive drop in input resistance in some muscle cells (6 and 7) but not others (12 and 13). The peptide also increased the amplitude of nerve-evoked contractions and compound excitatory junctional potentials (EJPs) to a greater degree in muscle cells 6 and 7 than 12 and 13. Knocking down FMRFamide receptor (FR) expression separately in nerve and muscle indicate that both presynaptic and postsynaptic FR expression contributed to the enhanced contractions, but EJP enhancement was mainly due to presynaptic expression. Muscle ablation showed that DPKQDFMRFa induced contractions and enhanced nerve-evoked contractions more strongly in muscle cells 6 and 7 than cells 12 and 13. In situ hybridization indicated that FR expression was significantly greater in muscle cells 6 and 7 than 12 and 13. Taken together, these results indicate that DPKQDFMRFa can elicit cell-selective effects on muscle fibers. The ability of neuropeptides to work in a cell-selective manner on neurons and muscle cells may help explain why so many peptides are encoded in invertebrate and vertebrate genomes.

scholarly journals Action of octopamine and tyramine on muscles of Drosophila melanogaster larvae

2013 ◽  
Vol 110 (8) ◽  
pp. 1984-1996 ◽  
Author(s):  
Kiel G. Ormerod ◽  
Julia K. Hadden ◽  
Lylah D. Deady ◽  
A. Joffre Mercier ◽  
Jacob L. Krans
Keyword(s):  
Neuromuscular Junctions ◽  
Neuromuscular Synapse ◽  
Force Production ◽  
Input Resistance ◽  
Muscle Cells ◽  
Excitatory Junction Potentials ◽  
A Cell ◽  
Chemical Synapses ◽  
Stimulation Paradigm ◽  
Muscle Force Production

Octopamine (OA) and tyramine (TA) play important roles in homeostatic mechanisms, behavior, and modulation of neuromuscular junctions in arthropods. However, direct actions of these amines on muscle force production that are distinct from effects at the neuromuscular synapse have not been well studied. We utilize the technical benefits of the Drosophila larval preparation to distinguish the effects of OA and TA on the neuromuscular synapse from their effects on contractility of muscle cells. In contrast to the slight and often insignificant effects of TA, the action of OA was profound across all metrics assessed. We demonstrate that exogenous OA application decreases the input resistance of larval muscle fibers, increases the amplitude of excitatory junction potentials (EJPs), augments contraction force and duration, and at higher concentrations (10−5 and 10−4 M) affects muscle cells 12 and 13 more than muscle cells 6 and 7. Similarly, OA increases the force of synaptically driven contractions in a cell-specific manner. Moreover, such augmentation of contractile force persisted during direct muscle depolarization concurrent with synaptic block. OA elicited an even more profound effect on basal tonus. Application of 10−5 M OA increased synaptically driven contractions by ∼1.1 mN but gave rise to a 28-mN increase in basal tonus in the absence of synaptic activation. Augmentation of basal tonus exceeded any physiological stimulation paradigm and can potentially be explained by changes in intramuscular protein mechanics. Thus we provide evidence for independent but complementary effects of OA on chemical synapses and muscle contractility.

scholarly journals Characterizing the physiological and behavioral roles of proctolin in Drosophila melanogaster

2016 ◽  
Vol 115 (1) ◽  
pp. 568-580 ◽  
Author(s):  
Kiel G. Ormerod ◽  
Olivia K. LePine ◽  
Maimoona Shahid Bhutta ◽  
JaeHwan Jung ◽  
Glenn J. Tattersall ◽  
...  
Keyword(s):  
Muscle Fibers ◽  
Muscle Cells ◽  
Receptor Expression ◽  
Dependent Manner ◽  
Impulse Frequency ◽  
Neuromuscular Systems ◽  
A Cell ◽  
Body Wall Muscles ◽  
Dose Dependent ◽  
Evoked Contractions

The neuropeptide proctolin (RYLPT) plays important roles as both a neurohormone and a cotransmitter in arthropod neuromuscular systems. We used third-instar Drosophila larvae as a model system to differentiate synaptic effects of this peptide from its direct effects on muscle contractility and to determine whether proctolin can work in a cell-selective manner on muscle fibers. Proctolin did not appear to alter the amplitude of excitatory junctional potentials but did induce sustained muscle contractions in preparations where the CNS had been removed and no stimuli were applied to the remaining nerves. Proctolin-induced contractions were dose-dependent, were reduced by knocking down expression of the Drosophila proctolin receptor in muscle tissue, and were larger in some muscle cells than others (i.e., larger in fibers 4, 12, and 13 than in 6 and 7). Proctolin also increased the amplitude of nerve-evoked contractions in a dose-dependent manner, and the magnitude of this effect was also larger in some muscle cells than others (again, larger in fibers 4, 12, and 13 than in 6 and 7). Increasing the intraburst impulse frequency and number of impulses per burst increased the magnitude of proctolin's enhancement of nerve-evoked contractions and decreased the threshold and EC50 concentrations for proctolin to enhance nerve-evoked contractions. Reducing proctolin receptor expression decreased the velocity of larval crawling at higher temperatures, and thermal preference in these larvae. Our results suggest that proctolin acts directly on body-wall muscles to elicit slow, sustained contractions and to enhance nerve-evoked contractions, and that proctolin affects muscle fibers in a cell-selective manner.

Rapid Dopaminergic Signaling by Interneurons That Contain Markers for Catecholamines and GABA in the Feeding Circuitry of Aplysia

2005 ◽  
Vol 93 (4) ◽  
pp. 2142-2156 ◽  
Author(s):  
Manuel Díaz-Ríos ◽  
Mark W. Miller
Keyword(s):  
Motor Neurons ◽  
Receptor Agonist ◽  
Input Resistance ◽  
Pattern Generator ◽  
Feeding Behaviors ◽  
Motor Programs ◽  
Pharmacological Tests ◽  
Specific Manner ◽  
Rapid Signaling ◽  
Functional Output

Consummatory feeding behaviors in Aplysia californica are controlled by a polymorphic central pattern generator (CPG) circuit. Previous investigations have demonstrated colocalization of markers for GABA and catecholamines within two interneurons, B20 and B65, that participate in configuring the functional output of this CPG. This study examined the contributions of GABA and dopamine (DA) to rapid synaptic signaling from B20 and B65 to follower cells that implement their specification of motor programs. Pharmacological tests did not substantiate the participation of GABA in the mediation of the excitatory postsynaptic potentials (EPSPs) from either B20 or B65. However, GABA and the GABAB receptor agonist baclofen were found to modify these signals in a target-specific manner. Several observations indicated that DA acts as the neurotransmitter mediating fast EPSPs from B20 to two radula closer motor neurons B8 and B16. In both motor neurons, application of DA produced depolarizing responses associated with decreased input resistance and increased excitation. B20-evoked EPSPs in both follower cells were occluded by exogenous dopamine and blocked by the DA antagonist sulpiride. While dopamine occlusion and sulpiride block of convergent signaling to B8 from B65 resembled that of B20, both of these actions were less potent on the rapid signaling from B65 to the multifunctional and widely acting interneuron B4/5. These findings indicate that dopamine mediates divergent (B20 to B16 and B8) and convergent (B20 and B65 to B8) rapid EPSPs from two influential CPG interneurons in which it is colocalized with GABA-like immunoreactivity.

scholarly journals Syntaxin 1A Gene Is Negatively Regulated in a Cell/Tissue Specific Manner by YY1 Transcription Factor, Which Binds to the −183 to −137 Promoter Region Together with Gene Silencing Factors Including Histone Deacetylase

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 146
Author(s):  
Takahiro Nakayama ◽  
Toshiyuki Fukutomi ◽  
Yasuo Terao ◽  
Kimio Akagawa
Keyword(s):  
Transcription Factor ◽  
Gene Silencing ◽  
Protein Complex ◽  
Promoter Region ◽  
Neuronal Cell ◽  
Syntaxin 1A ◽  
Tissue Specific ◽  
Cell Tissue ◽  
Specific Manner ◽  
A Cell

The HPC-1/syntaxin 1A (Stx1a) gene, which is involved in synaptic transmission and neurodevelopmental disorders, is a TATA-less gene with several transcription start sites. It is activated by the binding of Sp1 and acetylated histone H3 to the −204 to +2 core promoter region (CPR) in neuronal cell/tissue. Furthermore, it is depressed by the association of class 1 histone deacetylases (HDACs) to Stx1a–CPR in non-neuronal cell/tissue. To further clarify the factors characterizing Stx1a gene silencing in non-neuronal cell/tissue not expressing Stx1a, we attempted to identify the promoter region forming DNA–protein complex only in non-neuronal cells. Electrophoresis mobility shift assays (EMSA) demonstrated that the −183 to −137 OL2 promoter region forms DNA–protein complex only in non-neuronal fetal rat skin keratinocyte (FRSK) cells which do not express Stx1a. Furthermore, the Yin-Yang 1 (YY1) transcription factor binds to the −183 to −137 promoter region of Stx1a in FRSK cells, as shown by competitive EMSA and supershift assay. Chromatin immunoprecipitation assay revealed that YY1 in vivo associates to Stx1a–CPR in cell/tissue not expressing Stx1a and that trichostatin A treatment in FRSK cells decreases the high-level association of YY1 to Stx1a-CPR in default. Reporter assay indicated that YY1 negatively regulates Stx1a transcription. Finally, mass spectrometry analysis showed that gene silencing factors, including HDAC1, associate onto the −183 to −137 promoter region together with YY1. The current study is the first to report that Stx1a transcription is negatively regulated in a cell/tissue-specific manner by YY1 transcription factor, which binds to the −183 to −137 promoter region together with gene silencing factors, including HDAC.

scholarly journals AnIn VivoZebrafish Model for Interrogating ROS-Mediated Pancreaticβ-Cell Injury, Response, and Prevention

2018 ◽  
Vol 2018 ◽  
pp. 1-8 ◽  
Author(s):  
Abhishek A. Kulkarni ◽  
Abass M. Conteh ◽  
Cody A. Sorrell ◽  
Anjali Mirmira ◽  
Sarah A. Tersey ◽  
...  
Keyword(s):  
Cell Death ◽  
Caspase 3 ◽  
Cell Injury ◽  
Zebrafish Model ◽  
Chemical Genetic ◽  
Regulated Cell Death ◽  
Specific Manner ◽  
High Doses

It is well known that a chronic state of elevated reactive oxygen species (ROS) in pancreaticβ-cells impairs their ability to release insulin in response to elevated plasma glucose. Moreover, at its extreme, unmitigated ROS drives regulated cell death. This dysfunctional state of ROS buildup can result both from genetic predisposition and environmental factors such as obesity and overnutrition. Importantly, excessive ROS buildup may underlie metabolic pathologies such as type 2 diabetes mellitus. The ability to monitor ROS dynamics inβ-cells in situ and to manipulate it via genetic, pharmacological, and environmental means would accelerate the development of novel therapeutics that could abate this pathology. Currently, there is a lack of models with these attributes that are available to the field. In this study, we use a zebrafish model to demonstrate that ROS can be generated in aβ-cell-specific manner using a hybrid chemical genetic approach. Using a transgenic nitroreductase-expressing zebrafish line,Tg(ins:Flag-NTR)s950, treated with the prodrug metronidazole (MTZ), we found that ROS is rapidly and explicitly generated inβ-cells. Furthermore, the level of ROS generated was proportional to the dosage of prodrug added to the system. At high doses of MTZ, caspase 3 was rapidly cleaved,β-cells underwent regulated cell death, and macrophages were recruited to the islet to phagocytose the debris. Based on our findings, we propose a model for the mechanism of NTR/MTZ action in transgenic eukaryotic cells and demonstrate the robust utility of this system to model ROS-related disease pathology.

scholarly journals An in situ near-ambient pressure X-ray Photoelectron Spectroscopy study of Mn polarised anodically in a cell with solid oxide electrolyte

2015 ◽  
Vol 174 ◽  
pp. 532-541 ◽  
Author(s):  
Benedetto Bozzini ◽  
Matteo Amati ◽  
Patrizia Bocchetta ◽  
Simone Dal Zilio ◽  
Axel Knop-Gericke ◽  
...  
Keyword(s):  
Photoelectron Spectroscopy ◽  
Ambient Pressure ◽  
Solid Oxide ◽  
Spectroscopy Study ◽  
Solid Oxide Electrolyte ◽  
X Ray ◽  
A Cell ◽  
Oxide Electrolyte

scholarly journals Order and stochasticity in the folding of individual Drosophila genomes

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Sergey V. Ulianov ◽  
Vlada V. Zakharova ◽  
Aleksandra A. Galitsyna ◽  
Pavel I. Kos ◽  
Kirill E. Polovnikov ◽  
...  
Keyword(s):  
Random Walk ◽  
High Resolution ◽  
3D Genome ◽  
Topologically Associating Domains ◽  
Chromatin Folding ◽  
A Cell ◽  
Single Nucleus ◽  
High Level ◽  
Cell To Cell Variability

AbstractMammalian and Drosophila genomes are partitioned into topologically associating domains (TADs). Although this partitioning has been reported to be functionally relevant, it is unclear whether TADs represent true physical units located at the same genomic positions in each cell nucleus or emerge as an average of numerous alternative chromatin folding patterns in a cell population. Here, we use a single-nucleus Hi-C technique to construct high-resolution Hi-C maps in individual Drosophila genomes. These maps demonstrate chromatin compartmentalization at the megabase scale and partitioning of the genome into non-hierarchical TADs at the scale of 100 kb, which closely resembles the TAD profile in the bulk in situ Hi-C data. Over 40% of TAD boundaries are conserved between individual nuclei and possess a high level of active epigenetic marks. Polymer simulations demonstrate that chromatin folding is best described by the random walk model within TADs and is most suitably approximated by a crumpled globule build of Gaussian blobs at longer distances. We observe prominent cell-to-cell variability in the long-range contacts between either active genome loci or between Polycomb-bound regions, suggesting an important contribution of stochastic processes to the formation of the Drosophila 3D genome.

The testis-specific transcript (ferT) of the tyrosine kinase FER is expressed during spermatogenesis in a stage-specific manner

1990 ◽  
Vol 10 (9) ◽  
pp. 5021-5025
Author(s):  
E Keshet ◽  
A Itin ◽  
K Fischman ◽  
U Nir
Keyword(s):  
In Situ Hybridization ◽  
Tyrosine Kinase ◽  
Tyrosine Kinases ◽  
Meiotic Prophase ◽  
Hybridization Analysis ◽  
Pachytene Stage ◽  
Specific Transcript ◽  
Specific Manner

ferT is a testis-specific transcript of FER encoding a truncated version of the potential tyrosine kinase. Using in situ hybridization analysis, we found that ferT was transiently expressed during spermatogenesis and that expression was restricted to spermatocytes at the pachytene stage of meiotic prophase. This pattern of expression is unprecedented by other tyrosine kinases and suggests a role for ferT in a particular stage of spermatogenesis.

Beta-adrenergic actions on membrane electrical properties of dissociated smooth muscle cells

1988 ◽  
Vol 254 (3) ◽  
pp. C423-C431 ◽  
Author(s):  
H. Yamaguchi ◽  
T. W. Honeyman ◽  
F. S. Fay
Keyword(s):  
Smooth Muscle ◽  
Membrane Potential ◽  
Electrical Properties ◽  
Smooth Muscle Cells ◽  
Input Resistance ◽  
Muscle Cells ◽  
Resting Potential ◽  
Equilibrium Potential ◽  
Dependent Manner ◽  
Beta Adrenergic

Studies were carried out to determine the effects of the beta-adrenergic agent, isoproterenol (ISO), on membrane electrical properties in single smooth muscle cells enzymatically dispersed from toad stomach. In cells bathed in buffer of physiological composition, the average resting potential was -56.4 +/- 1.4 mV (mean +/- SE, n = 35). The dominant effect of exposure to ISO was hyperpolarization. The hyperpolarization was apparent in all cells studied and averaged 11.6 +/- 1.2 mV (n = 27). In the majority of the cells, hyperpolarization was accompanied by a decreased input resistance (Rin). Often the change in resistance appeared to lag behind the change in membrane potential. The lack of coincident changes in membrane potential and resistance may reflect a superposition of the outward rectification properties of the membrane on beta-adrenergic-induced increases in ionic conductance. In about half of the cells, an initial small depolarization (3.1 +/- 0.3 mV, n = 14) was accompanied by a small but distinct increase in Rin (12 +/- 2.5%). When membrane potential was made more negative than the estimated equilibrium potential for K+ (EK) by injection of current, ISO also produced biphasic effects, an initial hyperpolarization which reversed to a sustained depolarization to a value (-90 mV) near the estimated EK. The hyperpolarization by ISO could be diminished in a time-dependent manner by previous exposure to ouabain. The inhibition by ouabain, however, appeared to be a fortuitous result of glycoside-induced positive shifts in EK. These observations indicate that the dominant electrophysiological effect of beta-adrenergic stimuli is to hyperpolarize the cell membrane.(ABSTRACT TRUNCATED AT 250 WORDS)

Sign in / Sign up

Export Citation Format

Share Document