scholarly journals Systematic analysis of C. elegans embryo behavior reveals a stereotyped developmental progression and a rhythmic pattern of behavioral quiescence

2021 ◽  
Author(s):  
Evan L Ardiel ◽  
Andrew Lauziere ◽  
Stephen Xu ◽  
Brandon J Harvey ◽  
Ryan Christensen ◽  
...  
Keyword(s):  
Late Stage ◽  
Rhythmic Activity ◽  
Light Sheet ◽  
Rhythmic Pattern ◽  
Directed Motion ◽  
Systematic Analysis ◽  
C Elegans ◽  
Light Sheet Microscopy ◽  
Developmental Progression ◽  
Inactive Phase

Systematic analysis of rich behavioral recordings is being used to uncover how circuits encode complex behaviors. Here we apply the approach to embryos. What are the first embryonic behaviors and how do they evolve as early neurodevelopment ensues? To address these questions, we present a systematic description of behavioral maturation for Caenorhabditis elegans embryos. Posture libraries were derived from a genetically encoded motion capture suit imaged with light-sheet microscopy and annotated using custom semi-automated tracking software (Multiple Hypothesis Hypergraph Tracking; MHHT). Analysis of cell trajectories, postures, and behavioral motifs revealed a stereotyped developmental progression. Early movement is dominated by flipping between dorsal and ventral coiling, which gradually slows into a period of reduced motility. Late-stage embryos exhibit sinusoidal waves of dorsoventral bends, prolonged bouts of directed motion, and a rhythmic pattern of pausing, which we designate slow wave twitch (SWT). Synaptic transmission is required for late-stage motion but not for early flipping or the intervening inactive phase. A high-throughput behavioral assay and calcium imaging revealed that SWT is elicited by the rhythmic activity of a quiescence-promoting neuron (RIS). Similar periodic quiescent states are seen prenatally in divergent animals and may play an important role in promoting normal developmental outcomes.

scholarly journals Hydrogel encapsulation of living organisms for long-term microscopy

2017 ◽  
Author(s):  
Kyra Burnett ◽  
Eric Edsinger ◽  
Dirk R. Albrecht
Keyword(s):  
Light Sheet ◽  
C Elegans ◽  
Light Sheet Microscopy ◽  
Confined Spaces ◽  
Single Cell Imaging ◽  
Volumetric Images ◽  
Living Organisms ◽  
Resolution Single ◽  
Hydrogel Encapsulation

AbstractImaging living organisms at high spatial resolution requires effective and innocuous immobilization. Long-term imaging, across development or behavioral states, places further demands on sample mounting with minimal perturbation of the organism. Here we present a simple and inexpensive method for rapid encapsulation of small animals of any developmental stage within a photocrosslinked polyethylene glycol (PEG) hydrogel, gently restricting movement within their confined spaces. Immobilized animals maintained a normal, uncompressed morphology in a hydrated environment and could be exposed to different aqueous chemicals. We focus in particular on the nematode C. elegans, an organism that is typically viewed with paralyzing reagents, nanobeads, adhesives, or microfluidic traps. The hydrogel is optically clear, non-autofluorescent, and nearly index-matched with water for use with light-sheet microscopy. We captured volumetric images of optogenetically-stimulated responses in multiple sensory neurons over 14 hours using a diSPIM light-sheet microscope, and immobilized worms were recoverable and viable after 24 hours encapsulation. We further imaged living pygmy squid hatchlings to demonstrate size scalability, characterized immobilization quality for various crosslinking parameters and identified paralytic-free conditions suitable for high-resolution single cell imaging. PEG hydrogel encapsulation enables continuous observation for hours of small living organisms, from yeast to zebrafish, and is compatible with multiple microscope mounting geometries.

scholarly journals Regulation of RNA granule dynamics by phosphorylation of serine-rich, intrinsically disordered proteins in C. elegans

eLife ◽  
2014 ◽  
Vol 3 ◽  
Author(s):  
Jennifer T Wang ◽  
Jarrett Smith ◽  
Bi-Chang Chen ◽  
Helen Schmidt ◽  
Dominique Rasoloson ◽  
...  
Keyword(s):  
Intrinsically Disordered Proteins ◽  
Light Sheet ◽  
Disordered Proteins ◽  
Liquid Droplets ◽  
P Granules ◽  
C Elegans ◽  
Rna Granules ◽  
Intrinsically Disordered ◽  
Light Sheet Microscopy

RNA granules have been likened to liquid droplets whose dynamics depend on the controlled dissolution and condensation of internal components. The molecules and reactions that drive these dynamics in vivo are not well understood. In this study, we present evidence that a group of intrinsically disordered, serine-rich proteins regulate the dynamics of P granules in C. elegans embryos. The MEG (maternal-effect germline defective) proteins are germ plasm components that are required redundantly for fertility. We demonstrate that MEG-1 and MEG-3 are substrates of the kinase MBK-2/DYRK and the phosphatase PP2APPTR−½. Phosphorylation of the MEGs promotes granule disassembly and dephosphorylation promotes granule assembly. Using lattice light sheet microscopy on live embryos, we show that GFP-tagged MEG-3 localizes to a dynamic domain that surrounds and penetrates each granule. We conclude that, despite their liquid-like behavior, P granules are non-homogeneous structures whose assembly in embryos is regulated by phosphorylation.

scholarly journals Isoflurane Exposure in Juvenile Caenorhabditis elegans Causes Persistent Changes in Neuron Dynamics

2020 ◽  
Vol 133 (3) ◽  
pp. 569-582 ◽  
Author(s):  
Gregory S. Wirak ◽  
Christopher V. Gabel ◽  
Christopher W. Connor
Keyword(s):  
Caenorhabditis Elegans ◽  
Early Adulthood ◽  
Light Sheet ◽  
Loss Of Function ◽  
Behavioral Impairment ◽  
Mtor Inhibition ◽  
Late Adulthood ◽  
C Elegans ◽  
Light Sheet Microscopy ◽  
Activity Dynamics

Background Animal studies demonstrate that anesthetic exposure during neurodevelopment can lead to persistent behavioral impairment. The changes in neuronal function underlying these effects are incompletely understood. Caenorhabditis elegans is well suited for functional imaging of postanesthetic effects on neuronal activity. This study aimed to examine such effects within the neurocircuitry underlying C. elegans locomotion. Methods C. elegans were exposed to 8% isoflurane for 3 h during the neurodevelopmentally critical L1 larval stage. Locomotion was assessed during early and late adulthood. Spontaneous activity was measured within the locomotion command interneuron circuitry using confocal and light-sheet microscopy of the calcium-sensitive fluorophore GCaMP6s. Results C. elegans exposed to isoflurane demonstrated attenuation in spontaneous reversal behavior, persisting throughout the animal’s lifespan (reversals/min: untreated early adulthood, 1.14 ± 0.42, vs. isoflurane-exposed early adulthood, 0.83 ± 0.55; untreated late adulthood, 1.75 ± 0.64, vs. isoflurane-exposed late adulthood, 1.14 ± 0.68; P = 0.001 and 0.006, respectively; n > 50 animal tracks/condition). Likewise, isoflurane exposure altered activity dynamics in the command interneuron AVA, which mediates crawling reversals. The rate at which AVA transitions between activity states was found to be increased. These anesthetic-induced effects were more pronounced with age (off-to-on activity state transition time (s): untreated early adulthood, 2.5 ± 1.2, vs. isoflurane-exposed early adulthood, 1.9 ± 1.3; untreated late adulthood, 4.6 ± 3.0, vs. isoflurane-exposed late adulthood, 3.0 ± 2.4; P = 0.028 and 0.008, respectively; n > 35 traces acquired from more than 15 animals/condition). Comparable effects were observed throughout the command interneuron circuitry, indicating that isoflurane exposure alters transition rates between behavioral crawling states of the system overall. These effects were modulated by loss-of-function mutations within the FoxO transcription factor daf-16 and by rapamycin-mediated mechanistic Target of Rapamycin (mTOR) inhibition. Conclusions Altered locomotive behavior and activity dynamics indicate a persistent effect on interneuron dynamics and circuit function in C. elegansafter developmental exposure to isoflurane. These effects are modulated by a loss of daf-16 or mTOR activity, consistent with a pathologic activation of stress-response pathways. Editor’s Perspective What We Already Know about This Topic What This Article Tells Us That Is New

scholarly journals A systematic and quantitative comparison of lattice and Gaussian light-sheets

2020 ◽  
Author(s):  
Bo-Jui Chang ◽  
Kevin M. Dean ◽  
Reto Fiolka
Keyword(s):  
Optical Lattices ◽  
Numerical Aperture ◽  
Light Sheet ◽  
Resolving Power ◽  
Narrow Beam ◽  
Propagation Length ◽  
Systematic Analysis ◽  
Light Sheet Microscopy ◽  
Significant Interest ◽  
Confocal Parameter

AbstractThe axial resolving power of a light-sheet microscope is determined by the thickness of the illumination beam and the numerical aperture of its detection optics. Bessel-based optical lattices have generated significant interest owing to their potentially narrow beam waist and propagation-invariant characteristics. Yet, despite their significant use in Lattice Light-Sheet Microscopy, and recent incorporation into commercialized systems, there are very few quantitative reports on their physical properties and how they compare to standard Gaussian illumination beams. Here, we systematically measure the beam properties in transmission of dithered square lattices, which is the most commonly used variant of Lattice Light-Sheet Microscopy, and Gaussian-based light-sheets. After a systematic analysis, we find that square lattices are very similar to Gaussian-based light-sheets in terms of thickness, confocal parameter and propagation length.

scholarly journals Structural and developmental principles of neuropil assembly in C. elegans

2020 ◽  
Author(s):  
Mark W. Moyle ◽  
Kristopher M. Barnes ◽  
Manik Kuchroo ◽  
Alex Gonopolskiy ◽  
Leighton H. Duncan ◽  
...  
Keyword(s):  
Cell Tracking ◽  
Clustering Algorithm ◽  
Sensory Information ◽  
Coarse Graining ◽  
Light Sheet ◽  
Nerve Ring ◽  
C Elegans ◽  
Light Sheet Microscopy ◽  
Tissue Organization ◽  
Developmental Principles

SummaryNeuropil is a fundamental form of tissue organization within brains1. In neuropils, densely packed neurons synaptically interconnect into precise circuit architecture2,3, yet the structural and developmental principles governing nanoscale precision in bundled neuropil assembly remain largely unknown4–6. Here we use diffusion condensation, a coarse-graining clustering algorithm7, to identify nested circuit structures within the C. elegans cerebral neuropil (called the nerve ring). We determine that the nerve ring neuropil is organized into four tightly bundled strata composed of related behavioral circuits. We demonstrate that the stratified architecture of the neuropil is a geometrical representation of the functional segregation of sensory information and motor outputs, with specific sensory organs and muscle quadrants mapping onto particular neuropil strata. We identify groups of neurons with unique morphologies that integrate information across strata and that create a sophisticated honeycomb-shaped scaffold that encases the strata within the nerve ring. We resolve the developmental sequence leading to stratified neuropil organization through the integration of lineaging and cell tracking algorithms with high resolution light-sheet microscopy, and reveal principles of cell position, migration and hierarchical outgrowth that guide neuropil organization. Our results uncover conserved design principles underlying nerve ring neuropil architecture and function, and a pioneer neuron-based, temporal progression of outgrowth that guides the hierarchical development of the layered neuropil. Our findings provide a blueprint for using structural and developmental approaches to systematically understand neuropil organization within brains.

scholarly journals Imaging adult C. elegans live using light‐sheet microscopy

2020 ◽  
Author(s):  
J. VAN KRUGTEN ◽  
K.‐K.H. TARIS ◽  
ERWIN J.G. PETERMAN
Keyword(s):  
Light Sheet ◽  
C Elegans ◽  
Light Sheet Microscopy

scholarly journals Achromatic terahertz Airy beam generation with dielectric metasurfaces

Nanophotonics ◽  
2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Qingqing Cheng ◽  
Juncheng Wang ◽  
Ling Ma ◽  
Zhixiong Shen ◽  
Jing Zhang ◽  
...  
Keyword(s):  
Biomedical Imaging ◽  
Frequency Dispersion ◽  
Light Sheet ◽  
Photonic Devices ◽  
Self Healing ◽  
Beam Focusing ◽  
Light Sheet Microscopy ◽  
Airy Beam ◽  
Potential Applications ◽  
Airy Beams

AbstractAiry beams exhibit intriguing properties such as nonspreading, self-bending, and self-healing and have attracted considerable recent interest because of their many potential applications in photonics, such as to beam focusing, light-sheet microscopy, and biomedical imaging. However, previous approaches to generate Airy beams using photonic structures have suffered from severe chromatic problems arising from strong frequency dispersion of the scatterers. Here, we design and fabricate a metasurface composed of silicon posts for the frequency range 0.4–0.8 THz in transmission mode, and we experimentally demonstrate achromatic Airy beams exhibiting autofocusing properties. We further show numerically that a generated achromatic Airy-beam-based metalens exhibits self-healing properties that are immune to scattering by particles and that it also possesses a larger depth of focus than a traditional metalens. Our results pave the way to the realization of flat photonic devices for applications to noninvasive biomedical imaging and light-sheet microscopy, and we provide a numerical demonstration of a device protocol.

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