Laser Microsurgery in Caenorhabditis elegans

Fang-Yen, Christopher; Gabel, Christopher V.; Samuel, Aravinthan D. T.; Bargmann, Cornelia I.; Avery, Leon

doi:10.1016/b978-0-12-394620-1.00006-0

Cited by 112 publications

(99 citation statements)

References 74 publications

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“…Strains used and the procedure for isolating the allele pkc-1(pg5) are described in SI Materials and Methods. Laser ablation, KillerRed-mediated ablation, and Caspase-mediated ablation were performed using previously described methods, described in detail in SI Materials and Methods (18,19,41).…”

Section: Methodsmentioning

confidence: 99%

Bidirectional thermotaxis in Caenorhabditis elegans is mediated by distinct sensorimotor strategies driven by the AFD thermosensory neurons

Luo

Cook

Venkatachalam

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

103

116

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The nematode Caenorhabditis elegans navigates toward a preferred temperature setpoint (T s ) determined by long-term temperature exposure. During thermotaxis, the worm migrates down temperature gradients at temperatures above T s (negative thermotaxis) and performs isothermal tracking near T s . Under some conditions, the worm migrates up temperature gradients below T s (positive thermotaxis). Here, we analyze positive and negative thermotaxis toward T s to study the role of specific neurons that have been proposed to be involved in thermotaxis using genetic ablation, behavioral tracking, and calcium imaging. We find differences in the strategies for positive and negative thermotaxis. Negative thermotaxis is achieved through biasing the frequency of reorientation maneuvers (turns and reversal turns) and biasing the direction of reorientation maneuvers toward colder temperatures. Positive thermotaxis, in contrast, biases only the direction of reorientation maneuvers toward warmer temperatures. We find that the AFD thermosensory neuron drives both positive and negative thermotaxis. The AIY interneuron, which is postsynaptic to AFD, may mediate the switch from negative to positive thermotaxis below T s . We propose that multiple thermotactic behaviors, each defined by a distinct set of sensorimotor transformations, emanate from the AFD thermosensory neurons. AFD learns and stores the memory of preferred temperatures, detects temperature gradients, and drives the appropriate thermotactic behavior in each temperature regime by the flexible use of downstream circuits.N avigational behaviors provide a framework for exploring the interplay among sensorimotor circuits, learning, and memory. During a navigational task, animals eventually reach their goals by implementing strategies composed of sensorimotor rules. Experience can modify navigational goals, so memory can also be integrated into sensorimotor pathways. Studying navigation in the nematode Caenorhabditis elegans offers the possibility of understanding the plasticity and programming of sensorimotor circuits from input to output in a small nervous system (1).Previous studies established C. elegans thermotaxis as a model for experience-dependent navigation (2-6). When worms are exposed to specific temperatures between 15°C and 25°C for at least 4 h, they adopt those temperatures as their thermotactic setpoint (T s ) (2, 3, 5, 7). When placed on a spatial temperature gradient, worms seek the T s . When arriving near T s , worms track isotherms. Genetic analysis of thermotaxis has yielded mutants that are athermotactic (crawling randomly on temperature gradients), cryophilic (crawling to the coldest point on a temperature gradient irrespective of T s ), or thermophilic (crawling to the warmest point on a temperature gradient). This observation led to the suggestion that thermotaxis might involve separate circuits for negative thermotaxis (movement down gradients) and positive thermotaxis (movement up gradients) that balance near T s (2, 4).Systematic laser ablation a...

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Section: Methodsmentioning

confidence: 99%

Bidirectional thermotaxis in Caenorhabditis elegans is mediated by distinct sensorimotor strategies driven by the AFD thermosensory neurons

Luo

Cook

Venkatachalam

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

103

116

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“…Laser ablation was performed essentially as previously described (Fang‐Yen et al ., 2012). Briefly, arrested first larval‐stage animals were mounted on microscope slides with 2% agarose pads and anesthetized with 5 m m sodium azide.…”

Section: Methodsmentioning

confidence: 99%

Chemical activation of a food deprivation signal extends lifespan

Lucanic

Garrett

et al. 2016

Aging Cell

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SummaryModel organisms subject to dietary restriction (DR) generally live longer. Accompanying this lifespan extension are improvements in overall health, based on multiple metrics. This indicates that pharmacological treatments that mimic the effects of DR could improve health in humans. To find new chemical structures that extend lifespan, we screened 30 000 synthetic, diverse drug‐like chemicals in Caenorhabditis elegans and identified several structurally related compounds that acted through DR mechanisms. The most potent of these NP1 impinges upon a food perception pathway by promoting glutamate signaling in the pharynx. This results in the overriding of a GPCR pathway involved in the perception of food and which normally acts to decrease glutamate signals. Our results describe the activation of a dietary restriction response through the pharmacological masking of a novel sensory pathway that signals the presence of food. This suggests that primary sensory pathways may represent novel targets for human pharmacology.

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“…chemical genetics | neuronal silencing | neural circuits | avoidance behavior T he analysis of inactivating lesions has provided many insights into human and animal nervous systems, encouraging the development of sophisticated tools for neuronal silencing. In the nematode Caenorhabditis elegans, individual neurons can be killed by laser ablation, cell type-specific expression of caspases or toxic proteins, or genetically encoded photoactivatable toxins (1)(2)(3)(4)(5). Each of these methods has merits, but all are irreversible or poorly reversible.…”

mentioning

confidence: 99%

Inducible and titratable silencing ofCaenorhabditis elegansneurons in vivo with histamine-gated chloride channels

Pokala

Liu

Gordus

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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213

272

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Recent progress in neuroscience has been facilitated by tools for neuronal activation and inactivation that are orthogonal to endogenous signaling systems. We describe here a chemicalgenetic approach for inducible silencing of Caenorhabditis elegans neurons in intact animals, using the histamine-gated chloride channel HisCl1 from Drosophila and exogenous histamine. Administering histamine to freely moving C. elegans that express HisCl1 transgenes in neurons leads to rapid and potent inhibition of neural activity within minutes, as assessed by behavior, functional calcium imaging, and electrophysiology of neurons expressing HisCl1. C. elegans does not use histamine as an endogenous neurotransmitter, and exogenous histamine has little apparent effect on wild-type C. elegans behavior. HisCl1-histamine silencing of sensory neurons, interneurons, and motor neurons leads to behavioral effects matching their known functions. In addition, the HisCl1-histamine system can be used to titrate the level of neural activity, revealing quantitative relationships between neural activity and behavioral output. We use these methods to dissect escape circuits, define interneurons that regulate locomotion speed (AVA, AIB) and escape-related omega turns (AIB), and demonstrate graded control of reversal length by AVA interneurons and DA/VA motor neurons. The histamine-HisCl1 system is effective, robust, compatible with standard behavioral assays, and easily combined with optogenetic tools, properties that should make it a useful addition to C. elegans neurotechnology. chemical genetics | neuronal silencing | neural circuits | avoidance behavior

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Laser Microsurgery in Caenorhabditis elegans

Cited by 112 publications

References 74 publications

Bidirectional thermotaxis in Caenorhabditis elegans is mediated by distinct sensorimotor strategies driven by the AFD thermosensory neurons

Bidirectional thermotaxis in Caenorhabditis elegans is mediated by distinct sensorimotor strategies driven by the AFD thermosensory neurons

Chemical activation of a food deprivation signal extends lifespan

Inducible and titratable silencing ofCaenorhabditis elegansneurons in vivo with histamine-gated chloride channels

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