Davis L, Radman I, Goutou A, Tynan A, Baxter K, Xi Z, O’Shea JM, Chin JW, Greiss S. Precise optical control of gene expression in C elegans using improved genetic code expansion and Cre recombinase. Elife 2021;10:e67075. doi: 10.7554/eLife.67075.

 

Background: Genetic code expansion enables precise optical control of protein function through incorporation of non-canonical amino acids (ncAAs). In Caenorhabditis elegans, this approach allows for spatiotemporal manipulation of gene expression and neuronal activity. However, limitations in ncAA incorporation efficiency and cell-specific targeting have restricted its application in complex neural circuits.

 

Hypothesis: This study hypothesized that optimizing the genetic code expansion machinery and combining it with photoactivatable Cre recombinase would enable single-cell optical control of transgene expression in C. elegans, permitting functional dissection of individual neurons within bilateral pairs.

 

Methods: The authors improved ncAA incorporation by adding a strong nuclear export sequence to the pyrrolysyl-tRNA synthetase (PCKRS) and optimizing its cognate tRNA. They developed a light-activated Cre recombinase (optPC-Cre) and applied this LaserTAC system to induce gene expression in specific neurons. Behavioral responses were recorded using the WormLab Imaging System, and locomotion tracking and quantification were performed with WormLab.

 

Results: NES-tagged PCKRS variants increased ncAA incorporation efficiency, confirmed by fluorescence and western blot analyses. optPC-Cre achieved nearly complete recombination following light activation. Targeting of optogenetic channels to individual PLM neurons revealed that PLML and PLMR act synergistically in producing robust tail touch responses, with asymmetric contributions to habituation upon repeated stimulation.

 

Conclusions: The study established LaserTAC as a powerful tool for precise, single-cell genetic manipulation in C. elegans, enabling new insights into neural circuit function and offering broad applicability across tissues and model systems.

Nagarajan A, Ning Y, Reisner K, Buraei Z, Larsen JP, Hobert O, Doitsidou M. Progressive degeneration of dopaminergic neurons through TRP channel-induced cell death. J Neurosci 2014;34(17):5738-5746. doi: 10.1523/JNEUROSCI.4540-13.2014.

 

Background: Dopaminergic neurodegeneration underlies several human disorders, yet the genetic mechanisms that initiate and propagate neuronal loss remain poorly understood. Calcium dysregulation is a common feature of many neurodegenerative conditions, and members of the transient receptor potential (TRP) channel family have been implicated in cellular calcium homeostasis. However, mutations in TRP channels have not previously been shown to directly cause dopaminergic neuron degeneration.

 

Hypothesis: This study hypothesized that mutations in the trp-4 gene, which encodes a mechanosensitive TRP channel in Caenorhabditis elegans, lead to progressive dopaminergic neuron degeneration through calcium-dependent mechanisms.

 

Methods: The authors performed an unbiased forward genetic screen for mutants with progressive dopaminergic neuron loss, mapped mutations using whole-genome sequencing, and conducted behavioral and pharmacological analyses. Dopaminergic integrity was visualized using GFP reporters, and locomotor activity was quantified with WormLab.

 

Results: Two independent mutations, ot337 and ot477, were identified as gain-of-function alleles of trp-4, causing semidominant, progressive degeneration of head dopaminergic neurons. Degeneration was dopamine-independent, exhibited necrotic morphology, and was not suppressed by apoptotic pathway mutations. Chelation of cytoplasmic calcium or inhibition of endoplasmic reticulum calcium release (via crt-1, itr-1, unc-68, or dantrolene treatment) significantly suppressed neuronal loss.

 

Conclusions: Gain-of-function mutations in the TRP-4 channel induce calcium-mediated necrotic death of dopaminergic neurons in C. elegans. This model establishes TRP channel–related calcium dysregulation as a potential mechanism contributing to neurodegeneration.

Navarro-Hortal MD, Romero-Márquez JM, Muñoz-Ollero P, Jiménez-Trigo V, Esteban-Muñoz A, Tutusaus K, Giampieri F, Battino M, Sánchez-González C, Rivas-García L, Llopis J, Forbes-Hernández TY, Quiles JL. Amyloid β-but not Tau-induced neurotoxicity is suppressed by Manuka honey via HSP-16.2 and SKN-1/Nrf2 pathways in an in vivo model of Alzheimer’s disease. Food Funct 2022;13(21):11185-11199. doi: 10.1039/d2fo01739c.

 

Background: Alzheimer’s disease is a progressive neurodegenerative disorder characterized by β-amyloid (Aβ) aggregation and hyperphosphorylated Tau tangles, processes linked to oxidative stress. Natural products with antioxidant properties may ameliorate these pathologies, but the neuroprotective effects of Manuka honey (MH) had not been previously studied.

 

Hypothesis: This study hypothesized that Manuka honey could alleviate Aβ- and Tau-induced neurotoxicity in Caenorhabditis elegans through modulation of oxidative stress–related pathways.

 

Methods: The authors used several C. elegans strains, including Aβ- and Tau-expressing transgenics, to evaluate MH effects on oxidative stress, paralysis and locomotion. Phenolic composition and antioxidant capacity were measured, and RNA interference assays targeted stress-related genes. Locomotion parameters such as swimming speed, wavelength, and activity were analyzed using WormLab and the WormLab Imaging System.

 

Results: Manuka honey significantly reduced reactive oxygen species levels and delayed Aβ-induced paralysis, decreasing β-amyloid aggregation. RNAi experiments indicated that its protective effects required HSP-16.2 and SKN-1/Nrf2 pathways, while DAF-16 was not involved. Conversely, MH impaired locomotion in both wild-type and Tau-transgenic worms, an effect attributed to its sugar content rather than Tau aggregation.

 

Conclusions: Manuka honey improved oxidative stress resistance and reduced Aβ-induced neurotoxicity via HSP-16.2 and SKN-1/Nrf2 pathways, but its sugars negatively affected locomotor behavior. The study suggests that MH’s antioxidant activity underlies its selective neuroprotective effects.

Tiwari V, Buvarp E, Borbolis F, Puligilla C, Croteau DL, Palikaras K, Bohr VA. Loss of DNA glycosylases improves health and cognitive function in a C. elegans model of human tauopathy. Nucleic Acids Res 2024;52(18):10965-10985. doi: 10.1093/nar/gkae705.

 

Background: Alzheimer’s disease (AD) is characterized by amyloid plaques and tau neurofibrillary tangles, leading to oxidative DNA damage and neuronal dysfunction. Base excision repair (BER) is essential for maintaining genomic stability, but dysregulation of DNA glycosylases may contribute to neurodegeneration. Because Caenorhabditis elegans has only two DNA glycosylases, UNG-1 and NTH-1, it provides a simplified model to investigate how BER imbalance influences tau-associated pathology.

 

Hypothesis: This study hypothesized that genetic ablation of the DNA glycosylases NTH-1 and UNG-1 would mitigate tau-induced toxicity by reducing BER-associated DNA damage, thereby improving health span, mitochondrial function and cognition in C. elegans models of tauopathy.

 

Methods: The authors used transgenic C. elegans strains expressing aggregation-prone tau (BR5270) or control tau (BR5271), crossed with NTH-1 or UNG-1 mutants. Locomotion was quantified using WormLab, and lifespan, brood size and memory were assessed through established assays. RNA sequencing and immunohistochemistry were used to analyze transcriptional and cellular outcomes.

 

Results: Loss of NTH-1 or UNG-1 significantly improved lifespan, brood size and memory in tau-expressing worms. NTH-1 deficiency reduced oxidative DNA lesions and TUNEL-positive foci, enhanced mitochondrial membrane potential and extended survival under oxidative and genotoxic stress. RNAseq revealed extensive transcriptional reprogramming in NTH-1 mutants, distinct from UNG-1 deficiency.

 

Conclusions: These findings demonstrate that reduced BER initiation via DNA glycosylase loss alleviates tau-associated neurotoxicity, likely through decreased DNA damage and improved mitochondrial homeostasis. Modulating NTH-1 activity may thus represent a potential therapeutic strategy for AD.

Hochstrasser H, Kaub L, Maier L, Angstman NB, Kenmoku T, Nussbaum-Krammer C, Schmitz C. Behavioral changes in Caenorhabditis elegans after exposure to radial extracorporeal shock waves. J Clin Med 2025;14(20):7206. doi: 10.3390/jcm14207206.

 

Background: Cerebral palsy (CP) is a leading cause of childhood motor disability, often associated with spasticity. Radial extracorporeal shock wave therapy (rESWT) is a non-invasive treatment that reduces spasticity, but its mechanisms are unclear. The nematode Caenorhabditis elegans offers a well-characterized, cost-effective model for studying neuromuscular signaling, as its cholinergic neurotransmission and acetylcholine receptor subtypes resemble those of vertebrates.

 

Hypothesis: This study hypothesized that exposure of C. elegans to radial extracorporeal shock waves (rESWs) reduces the behavioral effects of the cholinergic agonists nicotine and carbachol, mediated via nicotinic acetylcholine receptors (nAChRs) at the neuromuscular junction (NMJ).

 

Methods: The authors exposed wild-type and acr-16 mutant C. elegans to various combinations of rESWs, nicotine and carbachol in liquid medium. Locomotor activity – quantified as peristaltic speed, wavelength, reversals and omega bends – was analyzed from high-resolution video recordings obtained with WormLab and the WormLab Imaging System.

 

Results: Exposure to rESWs transiently altered locomotion, mainly by reducing forward speed and increasing reversal frequency. Nicotine and carbachol alone or combined with rESWs caused modest or inconsistent effects on locomotor parameters. These behavioral changes were not clearly dependent on NMJ-associated nicotinic receptors, and recovery time modified the magnitude and direction of effects.

 

Conclusions: rESWs induced reversible behavioral alterations in C. elegans, indicating systemic nervous system effects beyond neuromuscular sites. While C. elegans may not directly model rESW-induced antispastic mechanisms in CP, the results suggest broader neuromodulatory actions of rESWs relevant to neurological disorders.

Lee H, Boor SA, Hilbert ZA, Meisel JD, Park J, Wang Y, McKeown R, Fischer SEJ, Andersen EC, Kim DH. Genetic variants that modify neuroendocrine gene expression and foraging behavior of C. elegans. Sci Adv 2024;10(24):eadk9481. doi: 10.1126/sciadv.adk9481.

 

Background: Behavioral diversity in animals often arises from genetic differences affecting neuronal gene expression, but the specific molecular mechanisms remain unclear. In Caenorhabditis elegans, the neuroendocrine ligand DAF-7, a transforming growth factor–β homolog, modulates foraging and feeding behaviors. Its neuron-specific expression is regulated by bacterial and environmental cues, suggesting that natural variation in daf-7 regulation may underlie behavioral differences across strains.

 

Hypothesis: This study hypothesized that naturally occurring genetic variants alter neuron-specific expression of the daf-7 gene in C. elegans and thereby contribute to diversity in foraging behavior.

 

Methods: The authors compared daf-7 expression in ASJ neurons among wild C. elegans strains using a transgenic daf-7p::GFP reporter and mapped causative variants through recombinant inbred lines and near-isogenic lines. Behavioral assays quantified roaming and dwelling states using video recordings analyzed with WormLab, and CRISPR-engineered alleles tested the causal roles of candidate variants in the gap-2 gene.

 

Results: Natural variation in daf-7 ASJ expression was observed among wild strains, with N2 showing the lowest levels. Two gap-2 missense variants (S64T and S11L) were identified that increased daf-7 ASJ expression and promoted roaming behavior relative to wild type. These effects were partially dependent on daf-7 function and acted cell nonautonomously through ADE neurons. The variants were prevalent in global populations, especially in European and African isolates.

 

Conclusions: The findings demonstrate that natural gap-2 variants modulate neuroendocrine daf-7 expression to influence foraging behavior. This work links genetic variation in neuronal signaling pathways to behavioral diversity in C. elegans and illustrates how neuroendocrine regulation contributes to adaptive behavioral traits.

Possik E, Schmitt C, Al-Mass A, Bai Y, Côté L, Morin J, Erb H, Oppong A, Kahloan W, Parker JA, Madiraju SRM, Prentki M. Phosphoglycolate phosphatase homologs act as glycerol-3-phosphate phosphatase to control stress and healthspan in C. elegans. Nat Commun 2022;13(1):177. doi: 10.1038/s41467-021-27803-6.

 

Background: Glycerol-3-phosphate phosphatase (G3PP) regulates glucose and lipid metabolism by hydrolyzing glycerol-3-phosphate (Gro3P) to glycerol. In mammals, G3PP protects against metabolic stress, but its in vivo physiological roles are incompletely understood. Because glycerol production in Caenorhabditis elegans is essential for osmotic adaptation and metabolic regulation, this nematode was used to explore the functions of G3PP homologs in stress responses and aging.

 

Hypothesis: This study hypothesized that G3PP homologs in C. elegans act as glycerol-3-phosphate phosphatases that protect against glucose and osmotic stress, regulate fat metabolism and promote healthy aging by limiting Gro3P-driven lipogenesis.

 

Methods: The authors identified three C. elegans G3PP homologs (pgph-1, pgph-2, pgph-3) and generated deletion and overexpression strains using CRISPR-Cas9 and transgenesis. Worm behaviors, lifespan, fat accumulation, stress resistance and glycerol metabolism were quantified. Locomotion and pumping rates were measured with WormLab to assess neuromuscular and feeding functions.

 

Results: Triple pgph mutants displayed reduced glycerol and increased Gro3P and fat deposition due to enhanced lipogenesis. pgph-2 emerged as the main isozyme required for glycerol synthesis and resistance to hyperosmotic and glucose-induced stress. Loss of PGPH enzymes shortened lifespan and healthspan, accelerated locomotor decline and heightened stress sensitivity. Conversely, pgph-2 overexpression decreased fat content, preserved motility and extended lifespan, especially under high-glucose conditions.

 

Conclusions: PGPH enzymes function as in vivo G3PPs that modulate metabolism and stress tolerance. By reducing lipogenesis and mimicking calorie restriction without altering food intake or fertility, PGPH activation promotes healthy aging in C. elegans.

Jiang L, Wang X, Zhang D, Yee Yuen KW, Tse YC. RSU-1 regulates the integrity of dense bodies in muscle cells of aging Caenorhabditis elegans. iScience 2024;27(6):109854. doi: 10.1016/j.isci.2024.109854.

 

Background: Muscle contraction depends on the sarcomere, whose dense bodies and M-lines ensure force transmission during locomotion. With aging, muscle strength and structure deteriorate, contributing to sarcopenia. The conserved Ras suppressor protein RSU-1 localizes to the dense body and M-line in Caenorhabditis elegans muscle cells, yet its precise role in maintaining sarcomere integrity during aging has remained unclear.

Hypothesis: This study hypothesized that RSU-1, through its interaction with UNC-97/PINCH, is essential for preserving dense body and M-line structure and thus maintaining muscle integrity and locomotion in aging C. elegans.

 

Methods: The authors employed transgenic C. elegans strains expressing fluorescently tagged RSU-1 and UNC-97 to visualize their localization by high-resolution confocal microscopy. Locomotion and burrowing abilities were quantified using WormLab. Structural analyses of muscle sarcomeres were performed through phalloidin staining, immunofluorescence of myosin filaments and transmission electron microscopy.

 

Results: RSU-1 colocalized with UNC-97 at dense bodies and M-lines, forming donut-shaped structures. Loss of RSU-1 or disruption of its UNC-97 interaction did not affect young worms but significantly reduced locomotion and burrowing in aged worms. Aging mutants displayed disorganized actin and myosin filaments, elongated dense bodies, disrupted M-lines and fewer A-bands, demonstrating structural degeneration.

 

Conclusions: RSU-1 is crucial for maintaining sarcomere organization and muscle performance during aging. Its interaction with UNC-97 stabilizes dense bodies and M-lines, preventing premature sarcopenia in C. elegans.

Xie J, Cai R, Hou X, Zhao K, Xiao J, Cao Y, Liu X. Z-Astaxanthin exhibits superior anti-obesity effects in Caenorhabditis elegans: insights from geometric isomers and signaling pathways. J Sci Food Agric 2025;105(9):4795-4807. doi: 10.1002/jsfa.14202.

 

Background: Astaxanthin (AST) is a carotenoid found in aquatic organisms that exists in both all-E and Z isomeric forms. The Z isomers have been reported to exhibit stronger antioxidant and biological activity than the all-E form. Although all-E AST is known for its anti-obesity potential, the effects of its Z isomers have not been fully clarified. This study therefore investigated whether Z AST exhibits superior lipid-lowering and anti-obesity effects compared with all-E AST using Caenorhabditis elegans as a model organism.

 

Hypothesis: This study hypothesized that Z isomers of astaxanthin, particularly 9-Z and 13-Z AST, would exert stronger anti-obesity effects than the all-E form by modulating lipid metabolism and energy balance through distinct molecular pathways.

 

Methods: The authors used synchronized C. elegans cultured under normal and high-fat conditions, treating them with all-E, 9-Z or 13-Z AST (60 μM). Lipid accumulation was visualized using oil red O staining, triglycerides were quantified and fatty acid composition was analyzed by GC–MS. Food intake and locomotion were recorded using the WormLab Imaging System, and locomotion speed was quantified with WormLab. Gene expression of key lipid and energy-regulating pathways was assessed by qPCR and fluorescence imaging in wild-type and mutant nematodes.

 

Results: Z AST, especially 9-Z, significantly reduced total fat and triglyceride levels by 41.2% and decreased large lipid droplets by up to 85.5%. The ratio of oleic to stearic acid (C18:1Δ9/C18:0) fell by 60–73%. Z isomers enhanced locomotion, reduced food intake and more effectively downregulated sbp-1, mdt-15, daf-2, daf-16, fat-6, and fat-7 than all-E AST.

 

Conclusions: Z-isomer astaxanthins exhibited markedly superior anti-obesity effects by suppressing lipid synthesis and promoting energy expenditure via sbp-1/mdt-15 and insulin signaling pathways. These findings highlight Z AST’s potential as an optimized bioactive compound for obesity prevention.

Kim AT, Li S, Kim Y, You YJ, Park Y. Food preference-based screening method for identification of effectors of substance use disorders using Caenorhabditis elegans. Life Sci 2024;345:122580. doi: 10.1016/j.lfs.2024.122580.

 

Background: Substance use disorders (SUD) affect millions globally and involve complex behavioral and neurochemical mechanisms. Opioid and endocannabinoid systems are key mediators of hedonic feeding and reward, but identifying effectors influencing these systems remains challenging. Caenorhabditis elegans, a model organism with conserved neurotransmission pathways, offers a simple platform to study such behaviors through quantifiable assays of food preference.

 

Hypothesis: This study hypothesized that modulation of opioid and cannabinoid receptors would alter C. elegans food preference behavior, enabling development of a screening assay to identify potential effectors of substance use–related systems.

 

Methods: The authors developed a binary food preference assay in C. elegans, assessing preference for high-quality (E. coli HB101) versus low-quality (Bacillus megaterium) food. They employed the WormLab Imaging System and WormLab to measure locomotion and analyze behavioral data. Wild-type, mutant and humanized strains expressing human μ-opioid receptor (MOPR) or cannabinoid 1 receptor (CB1R) were treated with known receptor agonists and antagonists.

 

Results: C. elegans preferred E. coli HB101 (preference index ≈0.2). Loperamide and ACEA (MOPR and CB1R agonists) increased, while naloxone and rimonabant decreased the preference index in receptor-dependent manners. Dopaminergic, serotonergic and olfactory mutants retained these responses. Humanized strains phenocopied wild-type results. Esculetin and L-theanine decreased preference via MOPR and CB1R, respectively.

 

Conclusions: Opioid and endocannabinoid signaling modulate food preference in C. elegans. This validated assay provides a rapid, behavior-based screening tool to identify modulators of MOPR and CB1R with translational potential for substance use disorder research.