scholarly journals Neuroendocrine Modulation Sustains the C. elegans Forward Motor State

2016 ◽  
Author(s):  
Maria A. Lim ◽  
Jyothsna Chitturi ◽  
Valeriya Laskova ◽  
Jun Meng ◽  
Daniel Findeis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Calcium Imaging ◽  
Neural Circuit ◽  
Transcriptome Profiling ◽  
Behavioral State ◽  
Forward Movement ◽  
C Elegans ◽  
Peptidergic Neuron ◽  
Homeobox Transcription Factor

AbstractNeuromodulators shape neural circuit dynamics. Combining electron microscopy, genetics, transcriptome profiling, calcium imaging, and optogenetics, we discovered a peptidergic neuron that modulates C. elegans motor circuit dynamics. The Six/SO-family homeobox transcription factor UNC-39 governs lineage-specific neurogenesis to give rise to a neuron RID. RID bears the anatomic hallmarks of a specialized endocrine neuron: it harbors near-exclusive dense core vesicles that cluster periodically along the axon, and expresses multiple neuropeptides, including the FMRF-amide-related FLP-14. RID activity increases during forward movement. Ablating RID reduces the sustainability of forward movement, a phenotype partially recapitulated by removing FLP-14. Optogenetic depolarization of RID prolongs forward movement, an effect reduced in the absence of FLP-14. Together, these results establish the role of a neuroendocrine cell RID in sustaining a specific behavioral state in C. elegans.

scholarly journals Neuroendocrine modulation sustains the C. elegans forward motor state

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Maria A Lim ◽  
Jyothsna Chitturi ◽  
Valeriya Laskova ◽  
Jun Meng ◽  
Daniel Findeis ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Calcium Imaging ◽  
Neural Circuit ◽  
Transcriptome Profiling ◽  
Behavioral State ◽  
Forward Movement ◽  
C Elegans ◽  
Peptidergic Neuron ◽  
Homeobox Transcription Factor

Neuromodulators shape neural circuit dynamics. Combining electron microscopy, genetics, transcriptome profiling, calcium imaging, and optogenetics, we discovered a peptidergic neuron that modulates C. elegans motor circuit dynamics. The Six/SO-family homeobox transcription factor UNC-39 governs lineage-specific neurogenesis to give rise to a neuron RID. RID bears the anatomic hallmarks of a specialized endocrine neuron: it harbors near-exclusive dense core vesicles that cluster periodically along the axon, and expresses multiple neuropeptides, including the FMRF-amide-related FLP-14. RID activity increases during forward movement. Ablating RID reduces the sustainability of forward movement, a phenotype partially recapitulated by removing FLP-14. Optogenetic depolarization of RID prolongs forward movement, an effect reduced in the absence of FLP-14. Together, these results establish the role of a neuroendocrine cell RID in sustaining a specific behavioral state in C. elegans.

scholarly journals Pan-neuronal screening in Caenorhabditis elegans reveals asymmetric dynamics of AWC neurons is critical for thermal avoidance behavior

eLife ◽  
2016 ◽  
Vol 5 ◽  
Author(s):  
Ippei Kotera ◽  
Nhat Anh Tran ◽  
Donald Fu ◽  
Jimmy HJ Kim ◽  
Jarlath Byrne Rodgers ◽  
...  
Keyword(s):  
Avoidance Behavior ◽  
Calcium Imaging ◽  
Functional Screening ◽  
Noxious Heat ◽  
Thermal Nociception ◽  
C Elegans ◽  
Low Efficiency ◽  
Behavioral Transition ◽  
Thermal Stimuli

Understanding neural functions inevitably involves arguments traversing multiple levels of hierarchy in biological systems. However, finding new components or mechanisms of such systems is extremely time-consuming due to the low efficiency of currently available functional screening techniques. To overcome such obstacles, we utilize pan-neuronal calcium imaging to broadly screen the activity of the C. elegans nervous system in response to thermal stimuli. A single pass of the screening procedure can identify much of the previously reported thermosensory circuitry as well as identify several unreported thermosensory neurons. Among the newly discovered neural functions, we investigated in detail the role of the AWCOFF neuron in thermal nociception. Combining functional calcium imaging and behavioral assays, we show that AWCOFF is essential for avoidance behavior following noxious heat stimulation by modifying the forward-to-reversal behavioral transition rate. We also show that the AWCOFF signals adapt to repeated noxious thermal stimuli and quantify the corresponding behavioral adaptation.

scholarly journals picd-1, a gene that encodes CABIN1 domain-containing protein, interacts with pry-1/Axin to regulate multiple processes in Caenorhabditis elegans

2021 ◽  
Author(s):  
Avijit Mallick ◽  
Shane K. B. Taylor ◽  
Sakshi Mehta ◽  
Bhagwati P. Gupta
Keyword(s):  
Stress Response ◽  
Essential Role ◽  
Family Members ◽  
Transcriptome Profiling ◽  
Scaffolding Protein ◽  
Dependent Manner ◽  
C Elegans ◽  
Downstream Effectors ◽  
Cellular Components

ABSTRACTAXIN family members control diverse biological processes in eukaryotes. As a scaffolding protein, AXIN facilitates interactions between cellular components and provides specificity to signaling pathways. Despite its crucial roles in metazoans and discovery of a large number of family members, the mechanism of AXIN function is not very well understood. The C. elegans AXIN homolog PRY-1 provides a powerful tool to identify interacting genes and downstream effectors that function in a conserved manner to regulate AXIN-mediated signaling. Previous work demonstrated pry-1’s essential role in developmental processes such as reproductive system, seam cells, and a P lineage cell P11.p. More recently, our lab carried out a transcriptome profiling of pry-1 mutant and uncovered the essential role of the gene in lipid metabolism, stress response, and aging. In this study, we have extended the work on pry-1 by reporting a novel interacting gene picd-1 (pry-1-interacting CABIN1 domain containing). Our findings have revealed that picd-1 plays an essential role in C. elegans and is involved in several pry-1-mediated processes including regulation of stress response and lifespan maintenance. In support of this, picd-1 expression overlaps with pry-1 in multiple tissues throughout the lifespan of animals. Further experiments showed that picd-1 inhibits CREB-regulated transcriptional coactivator homolog CRTC-1 function, which promotes longevity in a calcineurin-dependent manner. These data provide evidence for an essential role of the CABIN1 domain protein PICD-1 in mediating PRY-1 signaling in C. elegans.

scholarly journals Decoding a neural circuit controlling global animal state in C. elegans

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Patrick Laurent ◽  
Zoltan Soltesz ◽  
Geoffrey M Nelson ◽  
Changchun Chen ◽  
Fausto Arellano-Carbajal ◽  
...  
Keyword(s):  
Sensory Neurons ◽  
Neural Circuit ◽  
Behavioral State ◽  
Global State ◽  
C Elegans ◽  
Neural Imaging ◽  
Neural Genes ◽  
O2 Concentration ◽  
High O2 ◽  
O2 Sensing

Brains organize behavior and physiology to optimize the response to threats or opportunities. We dissect how 21% O2, an indicator of surface exposure, reprograms C. elegans' global state, inducing sustained locomotory arousal and altering expression of neuropeptides, metabolic enzymes, and other non-neural genes. The URX O2-sensing neurons drive arousal at 21% O2 by tonically activating the RMG interneurons. Stimulating RMG is sufficient to switch behavioral state. Ablating the ASH, ADL, or ASK sensory neurons connected to RMG by gap junctions does not disrupt arousal. However, disrupting cation currents in these neurons curtails RMG neurosecretion and arousal. RMG signals high O2 by peptidergic secretion. Neuropeptide reporters reveal neural circuit state, as neurosecretion stimulates neuropeptide expression. Neural imaging in unrestrained animals shows that URX and RMG encode O2 concentration rather than behavior, while the activity of downstream interneurons such as AVB and AIY reflect both O2 levels and the behavior being executed.

scholarly journals Potential role of a ventral nerve cord central pattern generator in forward and backward locomotion in Caenorhabditis elegans

2018 ◽  
Vol 2 (3) ◽  
pp. 323-343 ◽  
Author(s):  
Erick O. Olivares ◽  
Eduardo J. Izquierdo ◽  
Randall D. Beer
Keyword(s):  
Nerve Cord ◽  
Ventral Nerve Cord ◽  
Computational Models ◽  
Neural Circuit ◽  
Central Pattern Generators ◽  
C Elegans ◽  
Segmentation Analysis ◽  
Pattern Generators ◽  
Neural Unit

C. elegans locomotes in an undulatory fashion, generating thrust by propagating dorsoventral bends along its body. Although central pattern generators (CPGs) are typically involved in animal locomotion, their presence in C. elegans has been questioned, mainly because there has been no evident circuit that supports intrinsic network oscillations. With a fully reconstructed connectome, the question of whether it is possible to have a CPG in the ventral nerve cord (VNC) of C. elegans can be answered through computational models. We modeled a repeating neural unit based on segmentation analysis of the connectome. We then used an evolutionary algorithm to determine the unknown physiological parameters of each neuron so as to match the features of the neural traces of the worm during forward and backward locomotion. We performed 1,000 evolutionary runs and consistently found configurations of the neural circuit that produced oscillations matching the main characteristic observed in experimental recordings. In addition to providing an existence proof for the possibility of a CPG in the VNC, we suggest a series of testable hypotheses about its operation. More generally, we show the feasibility and fruitfulness of a methodology to study behavior based on a connectome, in the absence of complete neurophysiological details.

scholarly journals Excitatory Motor Neurons are Local Central Pattern Generators in an Anatomically Compressed Motor Circuit for Reverse Locomotion

2017 ◽  
Author(s):  
Shangbang Gao ◽  
Sihui Asuka Guan ◽  
Anthony D. Fouad ◽  
Jun Meng ◽  
Taizo Kawano ◽  
...  
Keyword(s):  
Motor Neurons ◽  
Calcium Imaging ◽  
Central Pattern Generators ◽  
Oscillatory Activity ◽  
Intrinsic Activity ◽  
C Elegans ◽  
Class A ◽  
Cell Ablation ◽  
Pattern Generators

AbstractCentral pattern generators are cell‐ or network-driven oscillators that underlie motor rhythmicity. The existence and identity of C. elegans CPGs remain unknown. Through cell ablation, electrophysiology, and calcium imaging, we identified oscillators for reverse locomotion. We show that the cholinergic and excitatory class A motor neurons exhibit intrinsic and oscillatory activity, and such an activity can drive reverse locomotion without premotor interneurons. Regulation of their oscillatory activity, either through effecting an endogenous constituent of oscillation, the P/Q/N high voltage-activated calcium channel UNC-2, or, via dual regulation – inhibition and activation ‐ by the descending premotor interneurons AVA, determines the propensity, velocity, and sustention of reverse locomotion. Thus, the reversal motor executors themselves serve as oscillators; regulation of their intrinsic activity controls the reversal motor state. These findings exemplify anatomic and functional compression: motor executors integrate the role of rhythm generation in a locomotor network that is constrained by small cell numbers.

A gross anatomical and histo-morphological study of the vagina of the emu (Dromaius novaehollandiae) and ostrich (Struthio camelus)

2008 ◽  
Vol 48 (10) ◽  
pp. 1332 ◽  
Author(s):  
M.-C. Madekurozwa
Keyword(s):  
Electron Microscopy ◽  
Electron Microscope ◽  
Light And Electron Microscopy ◽  
Forward Movement ◽  
Electron Microscope Level ◽  
Anatomical Features ◽  
Transmission Electron ◽  
Dromaius Novaehollandiae ◽  
Mucosal Folds

The present study details anatomical features of the lining of the emu and ostrich vagina, which in birds may impede the forward movement of spermatozoa. Vaginal samples were collected for light and electron microscopy. Samples for light microscopy were fixed in Bouin’s fluid, while samples for electron microscopy were fixed in 3% glutaraldehyde. After fixation the samples were processed routinely. A series of broad annular mucosal folds bearing convoluted primary folds were present in both ratites. The lining of the vaginal folds was a combination of ciliated, non-ciliated, vesicular and mitochondrial cells. The non-ciliated and a few ciliated cells, lining the crypts, contained mucin droplets. The role of the mucus is unclear. The results of the study show a similarity in the gross anatomical and scanning electron microscope features of the vagina in the emu and ostrich. Differences in the cellular composition of the vaginal epithelium were observed at the transmission electron microscope level.

scholarly journals MALT1 mediates IL-17 Neural Signaling to regulate C. elegans behavior, immunity and longevity

2019 ◽  
Author(s):  
Sean M. Flynn ◽  
Changchun Chen ◽  
Murat Artan ◽  
Stephen Barratt ◽  
Alastair Crisp ◽  
...  
Keyword(s):  
Nervous System ◽  
Neural Circuit ◽  
Escape Behavior ◽  
Interleukin 17 ◽  
Neural Function ◽  
Behavioral State ◽  
C Elegans ◽  
Nervous System Function ◽  
Circuit Function ◽  
Neural Signaling

AbstractBesides well-known immune roles, the evolutionarily ancient cytokine interleukin-17 (IL-17) modulates neural circuit function. We investigate how IL-17 signals in neurons, and the extent to which this signaling can alter organismal phenotypes. We combine immunoprecipitation and mass spectrometry to biochemically characterize endogenous signaling complexes that function downstream of IL-17 receptors in C. elegans (Ce) neurons. We identify the Ce ortholog of MALT1 as a critical output of the pathway. MALT1 was not previously implicated in IL-17 signaling or in nervous system function. MALT1 forms a complex with homologs of Act1 and IRAK and functions both as a scaffold for IκB recruitment, and as a protease. MALT1 is expressed broadly in the Ce nervous system, and neuronal IL-17–MALT1 signaling regulates many phenotypes, including escape behavior, associative learning, immunity and longevity. Our data suggest MALT1 has an ancient role modulating neural function downstream of IL-17 to remodel physiological and behavioral state.

scholarly journals Liprin-α/SYD-2 determines the size of dense projections in presynaptic active zones in C. elegans

2013 ◽  
Vol 203 (5) ◽  
pp. 849-863 ◽  
Author(s):  
Maike Kittelmann ◽  
Jan Hegermann ◽  
Alexandr Goncharov ◽  
Hidenori Taru ◽  
Mark H. Ellisman ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Caenorhabditis Elegans ◽  
High Resolution ◽  
Active Zone ◽  
Neuromuscular Junctions ◽  
Main Role ◽  
C Elegans ◽  
Active Zones ◽  
Dense Projections

Synaptic vesicle (SV) release is spatially and temporally regulated by a network of proteins that form the presynaptic active zone (AZ). The hallmark of most AZs is an electron-dense projection (DP) surrounded by SVs. Despite their importance for our understanding of triggered SV release, high-resolution analyses of DP structures are limited. Using electron microscopy, we show that DPs at Caenorhabditis elegans neuromuscular junctions (NMJs) were highly structured, composed of building units forming bays in which SVs are docked to the AZ membrane. Furthermore, larger ribbonlike DPs that were multimers of the NMJ building unit are found at synapses between inter- and motoneurons. We also demonstrate that DP size is determined by the activity of the AZ protein SYD-2/Liprin-α. Whereas loss of syd-2 function led to smaller DPs, syd-2 gain-of-function mutants displayed larger ribbonlike DPs through increased recruitment of ELKS-1/ELKS. Therefore, our data suggest that a main role of SYD-2/Liprin-α in synaptogenesis is to regulate the polymerization of DPs.

Electron Microscopy of Metal-Matrix Composites

1970 ◽  
Vol 28 ◽  
pp. 404-405
Author(s):  
A. Lawley ◽  
M. R. Pinnel ◽  
A. Pattnaik
Keyword(s):  
Electron Microscopy ◽  
Metal Matrix Composites ◽  
Metal Matrix ◽  
Critical Evaluation ◽  
Elastic Behavior ◽  
Matrix Composites ◽  
Directionally Solidified ◽  
Fracture Characteristics ◽  
Broad Program

As part of a broad program on composite materials, the role of the interface on the micromechanics of deformation of metal-matrix composites is being studied. The approach is to correlate elastic behavior, micro and macroyielding, flow, and fracture behavior with associated structural detail (dislocation substructure, fracture characteristics) and stress-state. This provides an understanding of the mode of deformation from an atomistic viewpoint; a critical evaluation can then be made of existing models of composite behavior based on continuum mechanics. This paper covers the electron microscopy (transmission, fractography, scanning microscopy) of two distinct forms of composite material: conventional fiber-reinforced (aluminum-stainless steel) and directionally solidified eutectic alloys (aluminum-copper). In the former, the interface is in the form of a compound and/or solid solution whereas in directionally solidified alloys, the interface consists of a precise crystallographic boundary between the two constituents of the eutectic.

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