Behavioral control by depolarized and hyperpolarized states of an integrating neuron

Coordinated transitions between mutually exclusive motor states are central to behavioral decisions. During locomotion, the nematode Caenorhabditis elegans spontaneously cycles between forward runs, reversals, and turns with complex but predictable dynamics. Here, we provide insight into these dynamics by demonstrating how RIM interneurons, which are active during reversals, act in two modes to stabilize both forward runs and reversals. By systematically quantifying the roles of RIM outputs during spontaneous behavior, we show that RIM lengthens reversals when depolarized through glutamate and tyramine neurotransmitters and lengthens forward runs when hyperpolarized through its gap junctions. RIM is not merely silent upon hyperpolarization: RIM gap junctions actively reinforce a hyperpolarized state of the reversal circuit. Additionally, the combined outputs of chemical synapses and gap junctions from RIM regulate forward-to-reversal transitions. Our results indicate that multiple classes of RIM synapses create behavioral inertia during spontaneous locomotion.

Behavioral control by depolarized and hyperpolarized states of an integrating neuron by

10.1101/2021.02.19.431690 ◽

2021 ◽

Cited By ~ 1

Author(s):

Aylesse Sordillo ◽

Cornelia I. Bargmann

Keyword(s):

Caenorhabditis Elegans ◽

Gap Junctions ◽

Behavioral Control ◽

Spontaneous Behavior ◽

Chemical Synapses ◽

ABSTRACTCoordinated transitions between mutually exclusive motor states are central to behavioral decisions. During locomotion, the nematode Caenorhabditis elegans spontaneously cycles between forward runs, reversals, and turns with complex but predictable dynamics. Here we provide insight into these dynamics by demonstrating how RIM interneurons, which are active during reversals, act in two modes to stabilize both forward runs and reversals. By systematically quantifying the roles of RIM outputs during spontaneous behavior, we show that RIM lengthens reversals when depolarized through glutamate and tyramine neurotransmitters and lengthens forward runs when hyperpolarized through its gap junctions. RIM is not merely silent upon hyperpolarization: RIM gap junctions actively reinforce a hyperpolarized state of the reversal circuit. Additionally, the combined outputs of chemical synapses and gap junctions from RIM regulate forward-to-reversal transitions. Our results indicate that multiple classes of RIM synapses create behavioral inertia during spontaneous locomotion.

Dissection of neuronal gap junction circuits that regulate social behavior in Caenorhabditis elegans

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1621274114 ◽

2017 ◽

Vol 114 (7) ◽

pp. E1263-E1272 ◽

Cited By ~ 21

Author(s):

Heeun Jang ◽

Sagi Levy ◽

Steven W. Flavell ◽

Fanny Mende ◽

Richard Latham ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Gap Junctions ◽

Gap Junction ◽

Behavioral Responses ◽

Dominant Negative ◽

Complex Behavior ◽

Hub And Spoke ◽

Cellular Resolution ◽

Chemical Synapses ◽

Electrical Signaling

A hub-and-spoke circuit of neurons connected by gap junctions controls aggregation behavior and related behavioral responses to oxygen, pheromones, and food in Caenorhabditis elegans. The molecular composition of the gap junctions connecting RMG hub neurons with sensory spoke neurons is unknown. We show here that the innexin gene unc-9 is required in RMG hub neurons to drive aggregation and related behaviors, indicating that UNC-9–containing gap junctions mediate RMG signaling. To dissect the circuit in detail, we developed methods to inhibit unc-9–based gap junctions with dominant-negative unc-1 transgenes. unc-1(dn) alters a stomatin-like protein that regulates unc-9 electrical signaling; its disruptive effects can be rescued by a constitutively active UNC-9::GFP protein, demonstrating specificity. Expression of unc-1(dn) in RMG hub neurons, ADL or ASK pheromone-sensing neurons, or URX oxygen-sensing neurons disrupts specific elements of aggregation-related behaviors. In ADL, unc-1(dn) has effects opposite to those of tetanus toxin light chain, separating the roles of ADL electrical and chemical synapses. These results reveal roles of gap junctions in a complex behavior at cellular resolution and provide a tool for similar exploration of other gap junction circuits.

Electrical synaptic transmission requires a postsynaptic scaffolding protein

10.1101/2020.12.03.410696 ◽

2020 ◽

Author(s):

Abagael M. Lasseigne ◽

Fabio A. Echeverry ◽

Sundas Ijaz ◽

Jennifer Carlisle Michel ◽

E. Anne Martin ◽

...

Keyword(s):

Synaptic Transmission ◽

Gap Junctions ◽

Functional Organization ◽

Scaffolding Protein ◽

Scaffolding Proteins ◽

Electrical Transmission ◽

Critical Function ◽

Electrical Synapses ◽

Intercellular Channels ◽

SUMMARYElectrical synaptic transmission relies on neuronal gap junctions containing channels constructed by Connexins. While at chemical synapses neurotransmitter-gated ion channels are critically supported by scaffolding proteins, it is unknown if channels at electrical synapses require similar scaffold support. Here we investigated the functional relationship between neuronal Connexins and Zonula Occludens 1 (ZO1), an intracellular scaffolding protein localized to electrical synapses. Using model electrical synapses in zebrafish Mauthner cells, we demonstrated that ZO1 is required for robust synaptic Connexin localization, but Connexins are dispensable for ZO1 localization. Disrupting this hierarchical ZO1/Connexin relationship abolishes electrical transmission and disrupts Mauthner-cell-initiated escape responses. We found that ZO1 is asymmetrically localized exclusively postsynaptically at neuronal contacts where it functions to assemble intercellular channels. Thus, forming functional neuronal gap junctions requires a postsynaptic scaffolding protein. The critical function of a scaffolding molecule reveals an unanticipated complexity of molecular and functional organization at electrical synapses.

The Caenorhabditis elegans DEG-3/DES-2 Channel Is a Betaine-Gated Receptor Insensitive to Monepantel

Molecules ◽

10.3390/molecules27010312 ◽

2022 ◽

Vol 27 (1) ◽

pp. 312

Author(s):

Tina V. A. Hansen ◽

Heinz Sager ◽

Céline E. Toutain ◽

Elise Courtot ◽

Cédric Neveu ◽

...

Keyword(s):

Caenorhabditis Elegans ◽

Nicotinic Acetylcholine Receptors ◽

Acetylcholine Receptors ◽

Parasitic Nematode ◽

Nematode Species ◽

Xenopus Laevis Oocytes ◽

Allosteric Modulators ◽

C Elegans ◽

Electrode Voltage ◽

Natural plant compounds, such as betaine, are described to have nematocidal properties. Betaine also acts as a neurotransmitter in the free-living model nematode Caenorhabditis elegans, where it is required for normal motility. Worm motility is mediated by nicotinic acetylcholine receptors (nAChRs), including subunits from the nematode-specific DEG-3 group. Not all types of nAChRs in this group are associated with motility, and one of these is the DEG-3/DES-2 channel from C. elegans, which is involved in nociception and possibly chemotaxis. Interestingly, the activity of DEG-3/DES-2 channel from the parasitic nematode of ruminants, Haemonchus contortus, is modulated by monepantel and its sulfone metabolite, which belong to the amino-acetonitrile derivative anthelmintic drug class. Here, our aim was to advance the pharmacological knowledge of the DEG-3/DES-2 channel from C. elegans by functionally expressing the DEG-3/DES-2 channel in Xenopus laevis oocytes and using two-electrode voltage-clamp electrophysiology. We found that the DEG-3/DES-2 channel was more sensitive to betaine than ACh and choline, but insensitive to monepantel and monepantel sulfone when used as direct agonists and as allosteric modulators in co-application with betaine. These findings provide important insight into the pharmacology of DEG-3/DES-2 from C. elegans and highlight the pharmacological differences between non-parasitic and parasitic nematode species.

Synaptic polarity and sign-balance prediction using gene expression data in the Caenorhabditis elegans chemical synapse neuronal connectome network

PLoS Computational Biology ◽

10.1371/journal.pcbi.1007974 ◽

2020 ◽

Vol 16 (12) ◽

pp. e1007974

Author(s):

Bánk G. Fenyves ◽

Gábor S. Szilágyi ◽

Zsolt Vassy ◽

Csaba Sőti ◽

Peter Csermely

Keyword(s):

Gene Expression ◽

Caenorhabditis Elegans ◽

Gene Expression Data ◽

Receptor Gene ◽

Directed Network ◽

Chemical Synapse ◽

Expression Data ◽

Chemical Synapses ◽

Theoretical Analyses ◽

Receptor Gene Expression

Graph theoretical analyses of nervous systems usually omit the aspect of connection polarity, due to data insufficiency. The chemical synapse network of Caenorhabditis elegans is a well-reconstructed directed network, but the signs of its connections are yet to be elucidated. Here, we present the gene expression-based sign prediction of the ionotropic chemical synapse connectome of C. elegans (3,638 connections and 20,589 synapses total), incorporating available presynaptic neurotransmitter and postsynaptic receptor gene expression data for three major neurotransmitter systems. We made predictions for more than two-thirds of these chemical synapses and observed an excitatory-inhibitory (E:I) ratio close to 4:1 which was found similar to that observed in many real-world networks. Our open source tool (http://EleganSign.linkgroup.hu) is simple but efficient in predicting polarities by integrating neuronal connectome and gene expression data.

Electron microscopy of Golgi-impregnated photoreceptors reveals connections between red and green cones in the turtle retina

Journal of Neurophysiology ◽

10.1152/jn.1985.54.2.304 ◽

1985 ◽

Vol 54 (2) ◽

pp. 304-317 ◽

Cited By ~ 34

Author(s):

H. Kolb ◽

J. Jones

Keyword(s):

Electron Microscopy ◽

Light Microscopy ◽

Gap Junctions ◽

Plexiform Layer ◽

Thin Sections ◽

Turtle Species ◽

Ribbon Synapses ◽

Central Elements ◽

Spectral Identity ◽

Red and green cones of two turtle species (Pseudemys scripta elegans and Chelydra serpentina) retina have been stained with Golgi procedures and examined by light microscopy of whole-mount tissue and by electron microscopy of serial thin sections. By light microscopy, red and green single cones appear indistinguishable, but double cones can be readily identified. All Golgi-stained photoreceptors in turtle retina have a spray of telodendria radiating from their synaptic pedicles. The telodendria of single cones are 10-20 micron long and end in clusters of terminals, whereas double cones have 30- to 50-micron long telodendria in addition to a very short bush of telodendria arising from one side of the pedicle. Electron microscopy of the Golgi-stained cones allows them to be distinguished into red or green spectral types by the appearance of their oil droplets. Furthermore, the spectral identity of cones contacted by the telodendria of identified Golgi-stained cones can similarly be determined. Red single cones make telodendrial contacts with other red singles, both members of the double cones, and with green single cones. Green single cones likewise connect to many surrounding red cones, both single and double types, and a few other green singles. Both members of the double cone connect to neighboring red and green singles and occasionally to double cones. The telodendria of stained cones end on spectrally homologous or heterologous cone types at basal junctions, central elements of ribbon synapses or, sometimes, as lateral elements of ribbon synapses. However, all these synaptic contacts appear to be of the same type, i.e., narrow-cleft basal junctions. Small gap junctions occur between neighboring cone pedicles, regardless of spectral type, in the visual streak area of the retina. Large gap junctions occur between unidentified cone telodendria in the neuropil of the outer plexiform layer. The telodendrial connections between red and green cones in the turtle retina have the appearance of chemical synapses and suggest an anatomical pathway responsible for the mixing of red and green signals in red or green cones of the turtle retina as reported in the accompanying physiological paper by Normann, Perlman, and Daly (27).

Ultrastructural analysis of chemical synapses and gap junctions betweenDrosophila brain neurons in culture

Developmental Neurobiology ◽

10.1002/dneu.20575 ◽

2008 ◽

Vol 68 (3) ◽

pp. 281-294 ◽

Cited By ~ 10

Author(s):

Hyun-Woo Oh ◽

Jorge M. Campusano ◽

Lutz G.W. Hilgenberg ◽

Xicui Sun ◽

Martin A. Smith ◽

...

Keyword(s):

Gap Junctions ◽

Ultrastructural Analysis ◽

Brain Neurons ◽

Gap junctions and chemical synapses

Nature ◽

10.1038/273410a0 ◽

1978 ◽

Vol 273 (5661) ◽

pp. 410-410

Author(s):

Anne Warner

Keyword(s):

Gap Junctions ◽

Experimental insight into the proximate causes of male persistence variation among two strains of the androdioecious Caenorhabditis elegans (Nematoda)

BMC Ecology ◽

10.1186/1472-6785-8-12 ◽

2008 ◽

Vol 8 (1) ◽

pp. 12 ◽

Cited By ~ 27

Author(s):

Viktoria Wegewitz ◽

Hinrich Schulenburg ◽

Adrian Streit

Keyword(s):

Caenorhabditis Elegans ◽

Proximate Causes ◽

The Factors that Affect Accountants' Decisions to Seek Careers with Big 4 versus Non-Big 4 Accounting Firms

Accounting Horizons ◽

10.2308/acch-50123 ◽

2012 ◽

Vol 26 (2) ◽

pp. 239-264 ◽

Cited By ~ 26

Author(s):

Penelope L. Bagley ◽

Derek Dalton ◽

Marc Ortegren

Keyword(s):

Behavioral Control ◽

Data Availability ◽

Accounting Students ◽

Perceived Behavioral Control ◽

Additional Insight ◽

Accounting Firms ◽

Accounting Professionals ◽

Big 4 ◽

Different Types ◽

SYNOPSIS Finding qualified accounting staff has consistently been a top issue facing CPA firms. However, little is known about the factors that influence accountants' decisions to seek careers with different types of firms. In our paper, we use Ajzen's (1991) theory of planned behavior to examine the reasons why some accountants seek careers at Big 4 firms, while other accountants seek careers at non-Big 4 firms. We survey accounting students and find that attitudes, subjective norms, and perceived behavioral control each influence firm-choice decisions. To provide additional insight into our results, we survey accounting professionals from Big 4 and non-Big 4 accounting firms. We find that, overall, students' perceptions, while more limited, are similar to those of accounting professionals. Further, we find that accounting professionals provide a number of insightful comments that offer several important implications for accounting firms. Finally, we assess whether accounting professionals perceive that certain types of accounting students are more likely to succeed at Big 4 versus non-Big 4 firms, and whether recruiting efforts are consistent with these perceptions. Data Availability: Data are available upon request.