Nictation Assays for Caenorhabditis and Other Nematodes

Lee, Daehan; Lee, Harksun; Choi, Myung-Kyu; Park, Sungsu; Lee, Jun-Ho

doi:10.21769/bioprotoc.1433

Cited by 14 publications

(29 citation statements)

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“…To establish whether natural strains of C. elegans vary in a potential dispersal behavior, we focused on nictation—a behavior where the long-lived dauer larvae lift and wave their bodies to increase interactions with larger, more mobile species. We used a previously established quantitative assay to measure the fraction of nictating dauers among a population of moving dauers 8 , 14 for a collection of genetically diverse wild strains (Fig. 1a and Supplementary Data 1 ).…”

Section: Resultsmentioning

confidence: 99%

“…Ten to twenty L4 larvae or young adults were transferred to synthetic pheromone plates containing agar (10 g/L), agarose (7 g/L), NaCl (2 g/L), KH 2 PO 4 (3 g/L), K 2 HPO 4 (0.5 g/L), cholesterol (8 mg/L), and synthetic pheromone-ascaroside 1, 2, 3 (2 mg/L each) 38 , 39 seeded with Escherichia coli OP50 at 25 °C for dauer induction 8 , 14 . After 4 days, dauers were morphologically identified by their dark intestines and radially constricted bodies.…”

Section: Methodsmentioning

confidence: 99%

“…After 4 days, dauers were morphologically identified by their dark intestines and radially constricted bodies. Micro-dirt chips were made by pouring 3.5% agar solution onto polydimethylsiloxane (PDMS) mold 14 . Solidified agar micro-dirt chip was detached from the PDMS mold and dried for 90 min at 37 °C.…”

Section: Methodsmentioning

confidence: 99%

“…Because natural variants are known to contribute to phenotypic differences in wild populations, quantitative genetic approaches have been used to successfully elucidate the molecular bases of the natural variation underlying a variety of C. elegans traits 10 – 13 . We investigated natural variation in the nictation behavior of C. elegans wild isolates, utilizing a previously established quantitative assay to measure the fraction of nictating dauers among a population of moving dauers 8 , 14 . We find significant differences among the strains, including two strains (N2 from Bristol, England and CB4856 from Hawaii, USA) for which recombinant inbred lines have been constructed to enable linkage-mapping approaches 15 .…”

Section: Introductionmentioning

confidence: 99%

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The genetic basis of natural variation in a phoretic behavior

et al. 2017

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Phoresy is a widespread form of commensalism that facilitates dispersal of one species through an association with a more mobile second species. Dauer larvae of the nematode Caenorhabditis elegans exhibit a phoretic behavior called nictation, which could enable interactions with animals such as isopods or snails. Here, we show that natural C. elegans isolates differ in nictation. We use quantitative behavioral assays and linkage mapping to identify a genetic locus (nict-1) that mediates the phoretic interaction with terrestrial isopods. The nict-1 locus contains a Piwi-interacting small RNA (piRNA) cluster; we observe that the Piwi Argonaute PRG-1 is involved in the regulation of nictation. Additionally, this locus underlies a trade-off between offspring production and dispersal. Variation in the nict-1 locus contributes directly to differences in association between nematodes and terrestrial isopods in a laboratory assay. In summary, the piRNA-rich nict-1 locus could define a novel mechanism underlying phoretic interactions.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The genetic basis of natural variation in a phoretic behavior

et al. 2017

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“…A chemosensory index (CI) was calculated following host-finding assays, giving a measure of relative attraction for participating IJs [8]. For the nictation assays, micro-dirt chips were made from a PDMS mould [26], with 3.5% ddH 2 O agar. 20 IJs suspended in 1.5 μl PBS were pipetted onto the micro-dirt chip, under a binocular light microscope.…”

Section: Methodsmentioning

confidence: 99%

Transcriptional variation and divergence of host-finding behaviour in Steinernema carpocapsae infective juveniles

et al. 2019

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BackgroundSteinernema carpocapsae is an entomopathogenic nematode that employs nictation and jumping behaviours to find potential insect hosts. Here we aimed to investigate the transcriptional basis of variant host-finding behaviours in the infective juvenile (IJ) stage of three S. carpocapsae strains (ALL, Breton and UK1), with a focus on neuronal genes known to influence behaviour in other nematode species. Identifying gene expression changes that correlate with variant host-finding behaviours will further our understanding of nematode biology.ResultsRNA-seq analysis revealed that whilst up to 28% of the S. carpocapsae transcriptome was differentially expressed (P < 0.0001) between strains, remarkably few of the most highly differentially expressed genes (> 2 log2 fold change, P < 0.0001) were from neuronal gene families. S. carpocapsae Breton displays increased chemotaxis toward the laboratory host Galleria mellonella, relative to the other strains. This correlates with the up-regulation of four srsx chemosensory GPCR genes, and a sodium transporter gene, asic-2, relative to both ALL and UK1 strains. The UK1 strain exhibits a decreased nictation phenotype relative to ALL and Breton strains, which correlates with co-ordinate up-regulation of neuropeptide like protein 36 (nlp-36), and down-regulation of an srt family GPCR gene, and a distinct asic-2-like sodium channel paralogue. To further investigate the link between transcriptional regulation and behavioural variation, we sequenced microRNAs across IJs of each strain. We have identified 283 high confidence microRNA genes, yielding 321 predicted mature microRNAs in S. carpocapsae, and find that up to 36% of microRNAs are differentially expressed (P < 0.0001) between strains. Many of the most highly differentially expressed microRNAs (> 2 log2 fold, P < 0.0001) are predicted to regulate a variety of neuronal genes that may contribute to variant host-finding behaviours. We have also found evidence for differential gene isoform usage between strains, which alters predicted microRNA interactions, and could contribute to the diversification of behaviour.ConclusionsThese data provide insight to the transcriptional basis of behavioural variation in S. carpocapsae, supporting efforts to understand the molecular basis of complex behaviours in nematodes.

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Three‐Dimensional Fruit Tissue Habitats for Culturing Caenorhabditis elegans

et al. 2021

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Environmental factors influence many traits of biological interest, but reproducing an animal's natural habitat in a controlled laboratory environment is challenging. Environmental enrichment-adding complexity to the usually simplistic conditions under which laboratory animals are raised-offers a potential tool for better understanding biological traits while maintaining controlled laboratory conditions. For the model nematode Caenorhabditis elegans, the contrast between the natural environment and the laboratory conditions in which they are raised is enormous. Although several methods have been developed in an effort to complexify C. elegans laboratory conditions, there is still a need for an enriched controlled laboratory habitat in which C. elegans can be raised over several generations, the bacterial food availability is similar to that in traditional agar plates, and the animals are crawling as opposed to swimming or burrowing. To this end, we describe here a standardized protocol for creating controlled, reproducible, three-dimensional environments for multigenerational maintenance of C. elegans in the laboratory. These environments are derived from decellularized apple hypanthium tissue and have bacterial food uniformly distributed throughout. We also describe how traditional C. elegans methods of collecting synchronized eggs, cleaning contaminated stocks, and collecting animal populations are adapted to our scaffold environment. These methods can be adapted to host different bacteria or bacterial populations, and the resulting scaffolds can be used in a range of experimental designs for behavioral and phenotypical studies in C. elegans and other nematodes.

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Nictation Assays for Caenorhabditis and Other Nematodes

Cited by 14 publications

References 2 publications

The genetic basis of natural variation in a phoretic behavior

The genetic basis of natural variation in a phoretic behavior

Transcriptional variation and divergence of host-finding behaviour in Steinernema carpocapsae infective juveniles

Three‐Dimensional Fruit Tissue Habitats for Culturing Caenorhabditis elegans

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