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Caenorhabditis elegans as a powerful tool in natural product bioactivity research
Applied Biological Chemistry volume 65, Article number: 18 (2022)
In addition to synthetic and semisynthetic compounds, natural products have received much attention as prolific sources of lead compounds with therapeutic effects on various diseases. In the process of screening the bioactivities of potential candidates, an in vivo assay is very important for providing meaningful insight into the efficacy, adverse effects, and modes of action that are relevant to humans. Among the many experimental models, Caenorhabditis elegans is particularly efficient due to its advantages in morphology, behavior, and genetic aspects. This review summarizes some basic and useful techniques commonly used in screening the bioactivities of natural products. Recent studies of naturally occurring extracts as well as bioactive compounds in various areas, namely, anti-aging, anti-neurodegeneration, anti-obesity, anti-infection, and gut health, are reviewed as examples of the applicability of the C. elegans model. Technological developments that incorporate C. elegans in other fields, such as instrumental analysis and emerging methods, are also discussed in this paper.
Caenorhabditis elegans is a small, transparent, free-living nematode that lives in soil . The organism has attracted attention for its use as an alternative in vivo model, especially in studies involving the potential biological activity of natural products (NPs). Due to its small size (approximately 1 mm in length for adults), C. elegans and its behavior, such as moving, eating, mating, and laying eggs, can be easily observed by microscopy. When comparing the genomes of humans and C. elegans, it is evident that many human disease genes and disease pathways are present in the worm. A total of 40–80% of human genes have orthologous genes in the C. elegans genome [2, 3], and 40–50% of human disease-associated genes have orthologs in the worm genome [3, 4]. Human disease-related and lipid metabolism genes and signaling pathways including the insulin signaling pathway are highly conserved in C. elegans [5, 6]. Because of these significant points, the nematode model has been utilized in a wide range of evaluations for therapeutic effects using bioactive NPs.
In this review, we described some basic C. elegans procedures in terms of morphological analysis, behavior analysis, biochemical analysis, and molecular assays. Many promising candidates in various areas from natural sources that have successfully been discovered using the C. elegans model are also summarized.
General information of C. elegans
Life cycle and anatomy
C. elegans are either self-fertilizing hermaphrodites or males; however, males account for approximately 0.1% of the population. Hermaphrodites that self-fertilize can produce approximately 300 offspring, whereas male-fertilized hermaphrodites can produce more than 1000 offspring. C. elegans has a short life cycle (3 days at 20 °C from eggs to gravid adults), and its life cycle consists of four larval stages (L1, L2, L3, and L4) and adulthood . Under optimal culture conditions, the average lifespan of C. elegans is 2 to 3 weeks . Figure 1 illustrates the life cycle of C. elegans.
The anatomy of C. elegans is simple and consists of the mouth, pharynx, intestine, gonad, and cuticle. It has a nervous system containing 302 neurons that are completely connected. The digestive system of C. elegans includes a pharynx, intestine, and rectum. The C. elegans intestine has various functions, such as food digestion by enzymes, nutrient absorption, and the synthesis and storage of various macromolecules. The intestine includes approximately 20 cells arranged to form a tube with a central lumen. The surface of intestinal cells carries numerous microvilli to increase the absorption surface .
Database of C. elegans
Currently, there are many databases available for research using the C. elegans model. WormAtlas (https://www.wormatlas.org/) is a valuable online database of nematode behavior and structural anatomy, anatomical methods, cell function, and cell identification. When examining the genomics of C. elegans, WormBase (http://www.wormbase.org/) is a helpful tool that provides information on the genetics, genomics, and biology of C. elegans, including gene sequences, gene expression patterns, loss-of-function mutants, RNAi phenotypes, and genetic maps. Many other online databases related to C. elegans, such as WormImage (http://www.wormimage.org/), which is a database of C. elegans electron micrographs and associated data, and WormBook (http://www.wormbook.org/), which contains basic reviews of C. elegans biology and methodology.
The advantages and disadvantages of the C. elegans model
Overall, C. elegans is a powerful model organism for research involving the biological activity of NP. This is not only because of the convenience of maintaining C. elegans in the laboratory but also because of its high fertility rates and short life cycle . In addition, the availability of its complete genome sequence makes C. elegans a valuable model for investigating the molecular basis of human diseases . Currently, with the development of many high-throughput screening (HTS) methods, thousands to millions of natural compounds can be simultaneously screened for targeted bioactivity. C. elegans, with its many advantages, such as its small size, short generation time with a high number of eggs, and short life cycle, has become a suitable candidate for HTS methods for new drug development from natural sources. Moreover, experiments with C. elegans do not have ethical concerns [10, 12].
However, using C. elegans still has some limitations compared to other mammalian animal models because C. elegans has a simple anatomy and lacks some mammalian organs or tissues, such as lungs, livers, kidneys, and blood transport systems. Therefore, it is not appropriate to use C. elegans as a research model for human diseases directly related to these organs . In addition, the small size (only 1.1 mm) of C. elegans can cause difficulties for inexperienced researchers in experimental manipulation. Each animal model has its own advantages and disadvantages, and the selection of model animals to use as a research model depends on many factors. Table 1 compares some of the advantages and limitations of commonly used model organisms including C. elegans, fruit fly (Drosophila melanogaster), zebrafish (Danio rerio), mouse (Mus musculus), and human cells.
Experimental techniques using C. elegans
Lifespan assays play an important role as markers for screening and elucidating the underlying molecular mechanism in studies involving aging, stress resistance, and toxicology . Due to its advantage of a relatively short life expectancy, a lifespan assay using C. elegans lasts for 21 days, and resistance assays with heat, chemical, or oxidative stress could last for a shorter duration [8, 13]. Lifespan assays can be conducted in both solid and liquid media. The traditional workflow involves counting the live and dead worms from an initial synchronized population over a period of time. The live and dead worms are recorded based on their responses to being touched with platinum wire in agar plates, shaking, or exposure to light or by the fluorescence signal from viable staining dye in the case of liquid media . Recently, a system using vibrotaxis with a controllable angular speed and a controllable duration of stimulus application was suggested to enhance the sensitivity and to minimize the mechanical damage to worms . The lifespan curve was then constructed based on the percentage of live worms. A detailed method was described in the review paper by Park et al. . This commonly used approach is labor intensive because it is necessary to regularly and manually transfer worms to fresh plates; thus, it is time consuming and inappropriate for assessing a large population of worms . Therefore, significant efforts have been made to provide increasingly automated approaches.
The last decade has shown an ever-increasing development of lifespan assays assisted by lab-on-chip methods. The general concept of this method is the fabrication of many chambers for housing worms on polymers, such as polydimethylsiloxane . Valves, pumps, and branching channels accurately facilitate all processes, such as feeding E. coli OP50, supplementing media or reagents, disposing waste and loading, sorting animals across progeny and immobilizing worms for imaging. The system is incorporated with an image acquisition module and software that allows real-time and automated scoring. Another automated technology that has been developed is the lifespan assay machine using a platform of standard Petri dishes or microfabricated well plates, which uses cessation in worm movement as a live or dead criterion. Some representative designs of microfluidic and automatic system, such as NemaLife chip, WorMotel, and WormBot, were previously thoroughly reviewed [15, 16]. All these approaches can be complementary to conventional methods that provide more reliable results.
Our group has reported a protocol for measuring the growth retardation of C. elegans treated with chemicals [17, 18]. Beginning with synchronized eggs, worms were incubated at 20 °C for 4 days. Microscopic images were taken every day for 4 days to exclude the possibility of starvation. Starvation was a considered possibility in the toxicity tests and was minimized by feeding worms a sufficient amount of E. coli or by adjusting the initial eggs. The growth rate assay can also be conducted in liquid with a 96-well plate platform using a high-throughput imaging analysis system to obtain microscopic pictures . Growth rate assays are especially useful in the assessment of toxins or side effects of bioactive substances at different developmental stages. Wittkowsky et al. demonstrated that correlation existed between the growth retardation effect of toxic chemical substances on C. elegans and a reduction in liver weight in rats .
Locomotion is a remarkable phenotype in studying aging, neuronal behavior, and metabolism in C. elegans. Worms have distinct forms of locomotion including swimming, burrowing, or crawling in response to complex environments, and these forms have a pattern that is classified into the following categories: forward locomotion, backward locomotion, dwelling, and quiescence . Despite some different patterns of motor control, swimming, and crawling are not qualitatively different, as there is a linear correlation among frequency and wavelength amplitude. In the laboratory, locomotive behaviors focus on kinematic parameters, especially forward locomotion, in the form of worm trails and shape. The basic assay follows the steps of transferring a number of worms into agar plates or liquid media and recording their movement under a microscope . The parameters of locomotion, such as body bends and velocity, can be calculated based on the frame-to-frame image of recoded video. The movement of the tip of the tail from one side to the other is counted as one body bend. The straightness rate was represented by the ratio of distance traveled to track the length. The dwelling time periods when the worms moved less than one body bend forward or backward are also determined. In addition to the manual count of body bends, models and software have been used to automatically analyze other motion parameters, such as wave initiation rate, asymmetry, stretch, and curling . For large-scale screening purposes, microfluidics technology has also been applied to evaluate worm locomotion in liquid environments. Recently, a 3D system to perform burrowing assays on Pluronic gel was reported .
Pharynx pumping assay
Caenorhabditis elegans is famous for its neural circuits underlying behavior, especially its feeding motion. The rhythmic feeding motions, termed pharyngeal pumping, are controlled by an autonomous network of 20 neurons of 14 types. Therefore, pharynx pumping is not only correlated with the rate of food intake and the rate of growth but is also connected with various chronic diseases, such as obesity, type 2 diabetes, cardiovascular diseases, and cancers [25, 26]. Similar to the locomotion assay, the conventional pharynx pumping assay relies on visually scoring pumps of short recordings during a particular time . Counting the number of pumps, which is one complete cycle of contraction and relaxation of the corpus and the terminal bulb, per minute is the simplest way to determine the pumping rate. Pharynx pumping assays are often used to estimate eating behavior changes and healthspan extension .
Egg laying assay
Caenorhabditis elegans egg laying is another established rhythmic behavior of interest in neuroscience and signaling research, as it is controlled by neural circuits and turns in behaviors . After egg synchronization, initial plates with and without the compound of interest that contained five L4 worms were prepared. Those worms were left to lay eggs and were transferred daily to fresh plates alongside the count of egg number laid on previous plates. In addition, the worms that crawled off, died, or were internally hatched were counted. The process continued until the adults stopped laying eggs, and approximately five days for the wild-type worms and total eggs at the end of the experiment were recorded . Egg laying assays can be used to evaluate the reproductive toxicity of chemicals [17, 18].
Another aspect of egg-laying behavior is the egg-in-worm assay, which counts the number of eggs retained in the uterus of C. elegans . Egg laying retention in is an effort to protect their progeny until the environment becomes more favorable, which indicates the toxicity of substances or drugs that affect neurotransmitter signaling. This assay takes advantage of bleaching solution to dissolve the cuticle, thus making the eggs visible.
Reactive oxygen species (ROS) measurement
ROS levels are a remarkable indicator of redox status, giving clues to inflammatory or aging processes . Due to transparency, using fluorescent or chemiluminescent probes that can be taken up by cells and emit detectable signals is a common method to measure ROS in C. elegans.
Generally, synchronized worms are routinely grown in nematode growth medium plates coated with E. coli OP50 as a food source. ROS measurement is often conducted under stress conditions such as toxins, heat, or supplementation with chemicals. On the day of the assessment, the worms were incubated with the target dye and permitted to eat the dye or transferred to a multiwell plate containing dye. After destaining the dye by washing or allowing animals to forage on seeded plates, fluorescence or chemiluminescence was measured in a microplate reader or by mounting the worms and was visualized under a fluorescence microscope. Confocal microscopy, electron spin resonance, or high-performance liquid chromatography (HPLC) with detection by absorbance, fluorescence, or mass spectrometry (MS) are also used for quantification .
Each dye has a specific mechanistic target for different types of ROS, enabling the tracking of ROS formation in specific compartments. For example, 2′,7′-dichlorodihydrofluorescein diacetate, the most common reporter for intracellular ROS, enters the membrane and is then converted to 2′,7′-dichlorodihydrofluorescein and then to 2′,7′-dichlorofluorescein, which is impermeable and highly fluorescent, upon oxidation [31, 32]. Regarding mitochondrial ROS, the MitoTracker Red CM-H2Xros or MitoSOX are useful probes for detecting O2• − or H2O2. Although MitoTracker Red has greater sensitivity, MitoSOX would be preferable over MitoTracker Red in certain cases due to its lower non-specific fluorescence . Other fluorescent probes have been used, such as peroxy orange I, 2-methyl-6-(p-methoxyphenyl)-3,7-dihydroimidazole[1,2-a]pyrazin-3-one (MCLA) or CellROX Green [34,35,36,37]. CellROX Green was used by Min et al. to study the influence of maternal nicotinamide supplementation on mitochondrial ROS in aged C. elegans . Most recently, a novel fluorogenic probe (CBH) , a nuclear-localized fluorescent probe (Nuclear Peroxy Emerald 1) , and a near-infrared fluorescent probe (DCHP)  with high sensitivity and selectivity have been introduced as promising analysis tools in studying oxidative-related conditions such as inflammation or Parkinson’s disease. The detailed characteristics of the probes used in C. elegans are summarized in Table 2.
The lipid content is an important indicator in elucidating metabolic disorders such as obesity . Although many microscopy techniques are able to visualize cellular lipids, such as conventional light microscopy, Raman microscopy, and anti-Stokes Raman microscopy, imaging techniques using fluorescent probes remain powerful to quantify lipid content and identify their distribution . Sudan Black, Oil Red O, boron dipyrromethene (BODIPY), and Nile red are common dyes that have been used in cells as well as C. elegans to stain lipid droplets, which are cellular organelles for lipid storage containing neutral lipid cores [43, 44]. Sudan Black and Oil Red O are azo dyes used to stain fixed animals. The fixation step takes place with the addition of isopropanol solution to the synchronized population. Worms are allowed to settle down before incubation with staining dyes such as Oil Red O or Sudan black. Finally, the staining solution was removed, and the fixed worms were mounted onto agarose pads for visualization under a microscope [42, 45]. The fixed staining procedure can be time-consuming and inconsistent due to artifacts during the fixation, permeabilization, and washing steps . The drawback of Oil Red O staining is that it is unable to visualize all fat stores in worms, and the signal from autofluorescence granules or lipofuscin and other nonspecific cellular organelles may decrease the accuracy . In contrast, vital dyes such as Nile red and BODIPY that stain living worms when mixed with E. coli as a food source examine fat content in intact living animals, which may analyze epistasis in large-scale analyses. This approach also incorporates RNA interference screening to demonstrate the roles of hundreds of fat-regulatory genes . However, the signal may be different with different endogenous uptake and transport pathways, affecting the conciseness in certain cases . For example, Nile red stains only lysosome-related organelles by accumulating in gut granules instead of all lipid stores. The result yielded by BODIPY staining was also variable because of the changes in dye uptake during food consumption. In addition to the common commercial lipid staining dyes mentioned, fluoranthene FLUN-550 and 7-((7-(4-methoxyphenyl)benzo[c]-[1,2,5]thiadiazol-4-yl)amino)-4-methyl-2H-chromen-2-one (BTD-Lip) were developed as new fluorescent probes for the selective quantification of intracellular lipid droplets [48, 49]. The staining pattern from BTD-Lip displayed a much more intense and highly specific signal without background noise than that of BODIPY .
Fluorescent protein expression
Since the first introduction of the gene for green fluorescent protein, gfp, in C. elegans by Dr. Chalfie in 1994, these genetically encoded sensors have become one of the standard tools of research in C. elegans. This technique is of significance in worms because of their transparency and thin diameter that allow live visualization under a fluorescence microscope . Moreover, fluorescent proteins can be targeted to specific locations, which is useful in many highly specific biological processes, such as ROS production. In particular, C. elegans possesses much larger gene families related to oxidative status and pathways than other model organisms and humans . The typical example is the group of superoxide dismutases (SODs). While most organisms have three SODs, five SODs are expressed in C. elegans.
A typical example of a protein probe in ROS evaluation is hydrogen peroxide sensor (HyPer), an H2O2-specific probe constructed by combining the H2O2-sensitive regulatory domain of the E. coli transcription factor OxyR and circularly permuted yellow fluorescent protein . When exposed to H2O2, an intramolecular cysteine disulfide bridge is formed, leading to a conformational change near the yellow fluorescent protein chromophore. HyPer has been applied in many studies in C. elegans. HyPer was modulated in the muscle cells of C. elegans, and therefore, the production patterns of H2O2 during the entire life span of wild-type N2, daf-2, and daf-16 mutants were revealed, in which the developmental stage had higher levels of H2O2, and this level was reduced at the start of the reproductive phase . This study showed that a major advantage is the monitoring of real-time H2O2 levels during aging, which is currently not possible in other model animals. One consideration when using HyPer is its sensitivity to pH changes and its overexpression.
In addition to direct ROS measurement, GFP mutant worms such as SKN-1::GFP or GST-4::GFP strains have been used as an indicator of oxidative state. As SKN-1 (mammalian Nrf2 homolog) induces phase II detoxification gene expression, which is required for oxidative stress resistance and longevity, nuclear localization assays and downstream gene expression using those mutant worms have been utilized to elucidate the signaling pathways of natural product bioactivities [54,55,56].
RNA interference (RNAi) assay
RNAi serves as a simple and quick tool for assessing genetic interactions by introducing a specific double-stranded RNA to worms to silence a particular gene. The loss-of-function phenotype observations may then reveal gene functions [57, 58]. In C. elegans, RNAi experiments can be performed in worms using several different protocols, including microinjection, feeding, and soaking. A detailed description can be found in the review of Zhuang et al. .
The choice of method for introducing RNA depends on the experimental purpose. Although microinjection may be more technically difficult than other approaches, it may also yield rapid results using in vitro double-stranded RNA through polymerase chain reaction. The simultaneous inhibition of two or more genes is also possible in this approach . In contrast, the feeding of double-stranded RNA in microtiter format is simple and requires no specific technical system . Despite its advantages, several important factors must be considered when interpreting RNAi results. The differences in the downregulation of gene expression depending on RNAi methods remain unclear. Moreover, there are differences between the knockdown phenotypes produced by RNAi and the genetic mutant phenotype .
Caenorhabditis elegans as useful tool in NP bioactivity research
Because of the advantages and available techniques mentioned above, many NP studies have been conducted using the C. elegans model. Table 3 summarizes some representative examples of the biological activities of NPs and probiotics in the C. elegans model.
Many potential bioactive NPs that extend the worm lifespan have been investigated. Plant extracts serve as important sources of potential lifespan extension materials such as Commiphora leptophloeos, tart cherry, Hibiscus sabdariffa L., ginseng, Glochidion zeylanicum, and Caesalpinia sappan L. [54,55,56, 61,62,63]. Phenethylamine and N-acetylphenethylamine are metabolites from the oral commensal bacterium Corynebacterium durum that induce a significant and dose-dependent increase in the lifespan of C. elegans . Among anti-aging and antioxidant NPs, many well-known anti-aging bioactive compounds are phenolic compounds such as myricetin, rutin, vitexin, quercetin, naringin, curcumin, epicatechin, and phenolic acids (protocatechuic, gallic, and vanillic acid) [63, 65, 66]. Curcumin, the pigment component from spices turmeric, is a well-known bioactive compound that has strong antioxidant activity due to the presence of phenolic hydroxyl groups at its active sites that quench ROS. Curcumin increased mean lifespan by 1.39 days under normal conditions as well as the survival rate during juglone-induced oxidative stress compared to those of the control group . Another example is myricetin, a widely distributed substance found in tea, berries, fruits, vegetables, and medicinal herbs. Myricetin enhanced both the lifespan and health span of C. elegans, as evidenced by the prolongation of the mean adult lifespan by 32.9% without an increase in the pharyngeal pumping rate and motility of aged worms .
A variety of high-throughput assays have been developed to analyze the molecular mechanism of NP bioactivity. Nonsense mutants of age-1, daf-2, and daf-16 are commonly used to identify biological pathways with lifespan-extending effects. The curcumin-mediated lifespan-extending effects mentioned were modulated by age-1 and skn-1 . A study demonstrated that fullerenol decreased the endogenous ROS levels and protected C. elegans by upregulating stress-related genes in a DAF-16-dependent manner, thus improving lifespan . In the case of myricetin, studies have suggested that the regulation of transcription factors DAF-16 (mammalian FOXO homolog) and SKN-1, the promotion of mitochondrial function via SIRT, and the inhibition of protein misfolding through protein aggregation are possible mechanisms of myricetin’s effects [68, 70,71,72]. SIRT was also found to be involved in the activity of other NPs, such as curcumin, monoamines, oligonol, and 5,5′-diferulic acid, suggesting that epigenetic mechanisms are potential targets in screening anti-aging compounds [64, 73,74,75].
Somatic aging is related to reproductive aging, which is the earliest aging phenotype in C. elegans . Reproductive aging begins in day-3 adult hermaphrodites, whereas intestinal aging begins in day-10 adult hermaphrodites . Furthermore, in the germ line of C. elegans hermaphrodites, the entire process of germ cell development, including germ cell proliferation, gametogenesis, and germ cell death, can be observed at the same time . Therefore, C. elegans is an excellent model organism to investigate reproductive capacity with age in association with somatic aging. It was previously reported that nicotinamide supplementation improves oocyte quality in an aging C. elegans model , suggesting that the roles of potential anti-aging NPs can be investigated to understand the molecular link between soma and the germ line in the process of aging using C. elegans as a model.
C. elegans stores fat in the form of lipid droplets in its intestinal and hypodermal cells instead of adipose tissue in mammals . With the ease of visualization under microscopy by using lipid staining dyes, C. elegans is useful in the screening of therapeutic compounds that potentially decrease body weight through the reduction in lipid droplets. Many plant extracts (Momordica charantia, Ilex paraguariensis, and chia seed oil) as well as compounds such as flavonoids (baicalein, chrysin, scutellarein, 6-hydroxyflavone, apigenin, chrysin, luteolin, kaempferol, myricetin, and quercetin) have been shown to reduce fat accumulation [79,80,81,82,83]. L1 worms treated with Ilex paraguariensis extract had 63.36% less intestinal fat than that of the control worms in the BODIPY fat staining assay . trans-Trismethoxy resveratrol, a methyl analog of resveratrol at a concentration of 200 μM, significantly reduced triglyceride accumulation by 20% without interfering with nematode growth, food intake, and fecundity . Similarly, luteolin showed a potent anti-fat effect, and the effect is mediated by the induction of lipolysis and fatty acid β-oxidation that is triggered by central serotonin signaling . Based on natural sources, the lipid-reducing efficacy of many nanoconstructions was also tested in the C. elegans model. Curcumin-loaded nanoemulsions and liposomes loaded with ethanolic extract of purple pitanga, exerted a significant fat reduction in C. elegans [85, 86]. In addition to the lipid-reducing effects in wild-type worms under normal conditions, diet-induced obesity and associated metabolic disorders were demonstrated. Momordica saponin extract significantly decreased the Oil Red O staining intensities by 21% and 24% in worms fed a normal diet and a glucose diet, respectively, which indicates the preventive and therapeutic effects of Momordica saponin extract . Barley β-glucan, one kind of polysaccharide from bitter melon, could reduce fat accumulation in C. elegans with excessive glucose intake via the insulin/IGF-1 and fatty acid desaturase-dependent pathways. It was also found that barley β-glucan reduced fat accumulation by affecting fat-5, fat-6, and fat-7, which mediated fatty acid desaturase pathways in C. elegans .
To date, many neurodegenerative disease models have been established using C. elegans, including models for Alzheimer’s disease (AD), Parkinson’s disease (PD), and polyglutamine expansion diseases . Through the overexpression of neurodegeneration-associated genes, such as beta amyloid (Aβ) peptides and neurofibrillary tangles of hyperphosphorylated tau proteins in AD or alpha-synuclein and other genes such as Lewy bodies in PD, clues were revealed through the correlations between the genotype of human diseases and the phenotypes of transgenic C. elegans. Based on this principle, the neuroprotective effects of various natural compounds, including Cleistocalyx nervosum var. paniala extract, magnolol from Magnolia officinalis, and caffeine were documented in the assessment of various worm strains [89,90,91]. Selvaraj et al. demonstrated the neuroprotective effect of a chalcone derivative in 6-hydroxyl dopamine-injured wild-type C. elegans N2, which is an experimental model of oxidative stress-induced dopaminergic neurodegeneration . CL4176 is a transgenic worm that possesses an Aβ-dependent paralysis phenotype due to the expression of the human Aβ1–42 peptide in muscle cells. Supplementation with magnolol (2.5–10 μM) delayed the onset of the paralyzed phenotype, in which the time to paralyze 50% of worms treated with 5 μM magnolol was 10 h, 20% longer than that in worms treated with accepted anti-AD drug . Caffeic acid (300 μM) prolonged the mean lifespan by 15.57%, and daf-16 expression was significantly upregulated in caffeic acid-treated CL4176 worms . Similarly, using another Aβ-expressing worm, CL2006, Cleistocalyx nervosum var. paniala extract (10 μg/mL) reduced Aβ toxicity by increasing the median lifespan to 28 days compared to the untreated control of 22 days. The effect was further explained through the involvement of the DAF-16 pathway, in which daf-16 was upregulated, while daf-2, age-1, and utx-1 were downregulated significantly .
In the PD model, the marker is the degeneration of dopaminergic neurons and the accumulation of Lewy bodies containing aggregated α-synuclein protein . Many extracts, including red seaweed Chondrus crispus, Sorbus alnifolia, Mucuna pruriens seed extract, Dioscorea alata L. tubers, and Holothuria leucospilota, were reported to reduce the aggregation of α-synuclein in a transgenic model expressing “human” α-synuclein worms [93,94,95,96,97]. Two polyphenols from olive oil, namely, hydroxytyrosol and oleuropein aglycone, attenuated the α-synuclein-induced locomotion impairments, in which the movement indexes, such as the wave initiation rate and body wave number on day-7 of adulthood. The increase in degenerated neurons with age was also completely blocked by 250 µg/mL of hydroxytyrosol . Worms grown from L1 on an E. coli diet supplemented with probiotic Bacillus subtilis crude extracts or vegetative pellets showed a reduction in α-synuclein aggregation, partially demonstrating the anti-Parkinson effect of active and stable B. subtilis metabolites .
Gut health improvement
C. elegans can be a good animal model for in vivo experiments to evaluate the effects of NPs on intestinal permeability and gut health. Le et al. established a high-throughput image analysis system that screens intestinal permeability alterations by various chemicals and pathogenic bacteria in C. elegans . Kim et al. demonstrated that 3,3′-diindolylmethane, a digestive metabolite from broccoli, ameliorated intestinal permeability dysfunction and extended the lifespan of C. elegans fed the intestinal pathogen P. aeruginosa PAO1 . The mean lifespan of 3,3′-diindolylmethane-treated worms (10.8 ± 1.3 days) was higher than that of the vehicle control worms (9.7 ± 1.1 days). The general working scheme of the phenotype-based gut permeability HTS of NPs against gut pathogens is illustrated in Fig. 2.
In addition, as bacteria associated with the animal gut are important for gastrointestinal function, C. elegans is a meaningful model to study the interaction among microbiota, pathogen, and food: the worms use bacteria as food, and the laboratory culture is a mono-association. Han et al. have suggested that the beneficial effects on longevity in worms may be exerted through modulation of the gut microbiota. E. coli mutants deficient in some biochemical components can extend C. elegans longevity. They reported that the increased secretion of the polysaccharide colanic acid by E. coli mutants extended the lifespan and decreased age-related pathologies by regulating mitochondrial dynamics and the unfolded protein response in C. elegans . Similarly, metformin, a synthetic derivative of guanidine, which is a drug for treating type 2 diabetes, can extend the lifespan and regulate lipid metabolism via production of agmatine, a metabolite derived from the gut microbiota . In addition to the metabolites from microbes, C. elegans was utilized to assess the effect of probiotic strains . Studies have shown that a strain of probiotic Lactobacillus rhamnosus or Weissella bacteria activates the DAF-16 signaling pathway and extends the lifespan of C. elegans compared to feeding with a normal diet of E. coli. L. casei rescued worms against K. pneumoniae infection by strengthening host resistance in a p38 MAPK-dependent manner . A study showed that a nonpathogenic strain of E. coli can increase the survival of enteropathogenic Escherichia coli-infected worms and interfere with pathogen colonization through a decrease in the luminal level of GFP-labeled enteropathogenic E. coli in the worm intestines. This protective effect that resulted from the improvement of epithelial cell integrity was also confirmed using two markers of tight junction protein, ZOO-1 (human ZO-1 homolog) and F10A3.1 (human claudin homolog) . Recently, Kim et al. reported that L. casei HY2782 treatment prevented a particulate matter-induced decline in reproduction and locomotion activity in C. elegans via the inhibition of intestinal cell death . However, because the main difference between the microbiota in C. elegans and humans is that the gut microbiota composition in the C. elegans experiment is a single bacterial species, further studies are needed to fill this gap.
Using a basic lifespan assay in a C. elegans pathogen infection model, many NPs exhibited antivirulence effects against a wide range of pathogens, such as Phyllanthus emblica, EGCG, lignans (sesamin and sesamolin) from Sesamum indicum, and clove bud oil against P. aeruginosa [108,109,110,111]. An in vivo assay using C. elegans has advantages over a conventional anti-infective screening approach because it can assess efficacy and toxicity at the same time, which eliminates compounds that are toxic to the host at early stages or have poor drug-like properties, while the latter identifies only direct antimicrobial compounds . The basic scheme is based on an excess of live worms compared to nontreated pathogen-infected nematodes to exclude both ineffective compounds and hit compounds that are highly toxic to worms. Based on this principle, Kong et al. successfully revealed that plant extract of Orthosiphon stamineus leaves and its active compound eupatorin improved the survival of S. aureus-infected worms through immunomodulation. They also found that liquid-based assays are more sensitive than conventional agar-based assays in detecting hit compounds . In addition, Yang et al. reported that the three major active compounds from rhubarb (emodin, rhein, and aloe-emodin) increased the survival of worms infected with S. aureus and inhibited the growth of S. aureus replication by using an integrated microfluidic platform . Toxicity tests serve as tools in discovered antihelminthic agents apart from antibacterial and antifungal compounds, and motility/mortality assays or locomotion bioassays have been used with wild-type and mutant C. elegans to screen nematocide compounds from traditional Chinese medicines .
When testing whole live C. elegans, the interaction between compounds and pathogens as well as the host immune system are easily observed, contributing to the identification of underlying anti-infective mechanisms. Using a worm model also enables the screening of bioactive compounds that only exhibit anti-infective effects in a host pathogen factor modulation-dependent manner. Figure 3 illustrates the use of C. elegans in revealing the mode of action in anti-infective studies. One strategy of bioactive compounds to suppress pathogen infection is to control the virulence of pathogens, such as bacterial membrane microdomains, toxin neutralization, biofilm inhibition, and quorum-sensing (QS) interference . QS is a complicated cell-to-cell communication system that regulates the expression of various virulence factors in gram-positive and negative bacteria, making it an attractive target for antivirulence treatment. It is also believed that QS-inhibiting agents could disrupt the protective biofilms of bacteria, leading to an increase in antimicrobial efficacy. Many natural inhibitors acting on QS and biofilms that have been tested using C. elegans are essential oils from Cymbopogon spp. and Cinnamomum verum against E. coli O157:H7, Diplocyclos palmatus against Serratia marcescens, 5-hydroxymethyl-2-furaldehyde from marine bacterium B. subtilis and Hibiscus sabdariffa extract against Candida albicans [117,118,119,120]. In the worm-S. marcescens infection model, 600 μg/mL D. palmatus extract extended the lifespan by 140 h compared with the 70 h control, which clearly confirmed the in vivo disease protection efficacy of D. palmatus extract. The results also proved that D. palmatus extract has anti-QS activity that further exhibits anti-adhesion activity on S. marcescens-infected C. elegans. through microscopic images and colony forming unit counting assays . Similarly, both broccoli extract and Bifidobacterium longum extract increase the survival of sick C. elegans by inhibiting QS signaling molecule-autoinducer-2 activity [121, 122].
Another mechanism of interest is the activation of the worm immune system. The polyphenols isolated from magnolia plants, i.e., honokiol and magnolol, rescued worms from S. aureus infection . The induced expression of lys-7, p38 MAP kinase, and insulin-like signaling pathways using GFP worms was evidence for the induction of innate defense by the plant extracts O. stamineus and D. palmatus [113, 117].
Antimicrobial photodynamic therapy (APDT) is an alternative therapeutic method for the control and treatment of pathogen infections. APDT is based on the use of photoactive dye molecules, which are widely known as photosensitizers. Upon irradiation with a specific wavelength of light, photosensitizers produce ROS that can destroy biomolecules such as lipids and proteins, causing microbial cell death . The APDT effects using plant-derived photosensitizers, hypericin and plant extract of Tripterygium wilfordii were evaluated on C. elegans infected with various pathogenic bacteria and fungi. After APDT using natural compounds and extracts, C. elegans survived without significant side effects, and the growth retardation induced by pathogen infections was reversed [125, 126].
Instrumental method for NP research using C. elegans
High-throughput screening using C. elegans
With the diversity of origin and structure of natural compounds, the screening of bioactive compounds is an emerging issue that needs to be investigated. Nowadays, with the development of many HTS methods, thousands to millions of natural compounds can be screened simultaneously for targeted bioactivity. Among many model animals, C. elegans is one of the most suitable for organism-level phenotype-based HTS because of its advantages such as small size, transparent body, cost effectiveness, maintainability, and speed. Natural compounds and extracts were assessed for bioactivity by evaluating various phenotypic characteristics, such as growth, lifespan, reproduction, movement of the worm, or intestinal permeability.
Moy et al. have developed an HTS method to find compounds that enhance the survival of C. elegans infected with E. faecalis. A total of 37,200 compounds and natural extracts were screened in this study, and 28 compounds and extracts were reported to have antimicrobial activity, but they did not affect the growth of the pathogen in vitro . A library of 1280 compounds was screened by Ye et al. to identify compounds that increase the lifespan of C. elegans. Sixty compounds were found to increase the longevity of worm, 33 of which also increased the oxidative stress resistance of C. elegans. Many of the candidate compounds are drugs approved for human use, such as minocycline hydrochloride, cinnarizine, and vincristine sulfate . Lucanic et al. screened over 300,000 compounds to identify new chemical structures that extend the lifespan of C. elegans through a dietary restriction mechanism. They described that out of 57 compounds found to prolong C. elegans lifespan, 3 compounds contained a nitrophenyl piperazine backbone and induced a significant lifespan extension . Taki et al. developed an HTS method to establish the effect of small molecules on the motility of C. elegans using infrared light interference. A total of 14,400 compounds were screened by this method, and the results showed that 43 compounds decreased worm motility by ≥ 70%, equating to a hit rate of 0.3% .
High-performance liquid chromatography (HPLC) for evaluating NP metabolism in C. elegans
HPLC is a simple, convenient method used for quantifying natural compounds. Zheng et al. evaluated the metabolism of resveratrol, a natural phenolic compound with a good antioxidant effect on C. elegans by HPLC. The results showed that the rate of metabolism of resveratrol was dependent on both dose and time. The concentration of resveratrol in worms ranged from approximately 300 to 600 mg/kg after treatment with 100 μM resveratrol, which was comparable with studies in mice, which ranged from 4.9 to 400 mg/kg . The HPLC–UV method was developed by Stupp et al. to evaluate the metabolism of two toxicants, 1-hydroxyphenazine and indole, released by P. aeruginosa and E. coli, respectively. The analysis results show that the worms can glycosylate both toxins, a metabolic modification that significantly decreases their toxicity .
Nuclear magnetic resonance (NMR) and mass spectrometry (MS) using C. elegans
NMR and MS have already been demonstrated to be effective tools for metabolic profiling in C. elegans by investigating the metabolism of amino acids, organic acids, choline, sugars, nucleotides, or cofactors . Figure 4 illustrates the use of NMR to study the metabolism of NP. NMR and MS have been used to investigate the metabolic changes in C. elegans exposed to toxicity. The metabolic change in C. elegans exposed to the heavy metal nickel, the pesticide chlorpyrifos, and their mixture was reported using gas chromatography–MS and NMR. It has been reported that novel metabolic profiles are associated with both exposure and dose levels. In addition, changes in branch chain amino acids and tricarboxylic acid cycle intermediates were also observed .
Ascarosides are a group of water-soluble small molecules secreted by C. elegans for chemical communication to control certain behaviors, such as mating attraction, aggregation, and avoidance. Zhang et al. reported an experimental method for analyzing the types and concentration of ascaroside in C. elegans by NMR and liquid chromatography-tandem mass spectrometry LC–MS/MS . Stasiuk et al. reported the biotransformation of five benzimidazole anthelmintics, namely, albendazole, mebendazole, thiabendazole, oxfendazole, and fenbendazole, in C. elegans by LC–MS/MS analysis. The results showed that glucose conjugation is the primary biotransformation pathway for benzimidazole drugs in C. elegans. The biotransformation of albendazole by C. elegans reduced drug efficacy and was inhibited by the UGT inhibitor chrysin . Interestingly, Nguyen et al. demonstrated real-time metabolomics changes in C. elegans by using in-organism NMR analysis . Currently, the applications of NMR and MS are mainly in studies of the metabolism of C. elegans. Therefore, these methods will be useful for evaluating the pharmacokinetics (absorption, distribution, metabolism, elimination, and toxicity) of natural compounds in the C. elegans model.
Emerging technologies in C. elegans studies
Currently, an increasing number of techniques have been developed to support research on the C. elegans model. Modern technologies, such as artificial intelligence, machine learning, and computational techniques, have been applied to simulate the body structure, nervous system, and behaviors of C. elegans. OpenWorm is one of the first projects to simulate C. elegans at the cellular level. This project’s long-term goal is to model all 959 cells of C. elegans, and users can access datasets about C. elegans neuronal structure .
An automatic pipeline, CShaper, was developed by Cao J et al. . It was applied to quantify the morphological parameters of cells in 17 developing C. elegans embryos. A time-lapse 3D atlas of cell morphology for the worm embryo from the 4- to 350-cell stages has been generated, which consists of cell shape, cell volume, cell surface area, cell migration, nucleus position, and cell-to-cell contact.
Xu et al. investigated the chemotaxis behaviors of C. elegans through association with biological nerve connections . These behaviors include food attraction, toxin avoidance, and mixed behaviors (finding food and avoiding toxins simultaneously). Eight dynamic neural network models, two artificial models, and six biological models were used to understand the chemotaxis behaviors of worm. The results showed that the developed models could effectively simulate the real chemotaxis behaviors of C. elegans in different environments.
Martineau et al. reported a multidimensional phenotyping method that predicts lifespan and quantifies healthspan in C. elegans . Multiple phenotypes at the organismal scale were characterized to measure the aging process, including the morphological, postural, and behavioral changes extracted from high-resolution videos. In a total of 1019 features extracted, 896 aging biomarkers correlated with relative age, and vector regression was used to predict the age, remaining life, and lifespan expectancy of worms. More features added to the model lead to an increase in the quality of the prediction.
Concluding remarks and future prospective
This article has included some general information about C. elegans and the advantages of applying the C. elegans model in NP bioactivity research. The mechanism of action at the cellular and molecular levels of natural compounds has also been elucidated through studies based on the C. elegans model. Techniques to evaluate the effects of NPs in the C. elegans model are also being improved and developed. Many valuable biological activities of NPs have been discovered and studied using C. elegans models, such as anti-aging, antiobesity, anti-neurodegeneration, gut health improvement, and anti-infective effects. With the diversity in the number and structure of natural compounds, HTS methods are essential to shorten research time and save costs for screening and discovering natural compounds with interesting biological effects. With the advantages of their body composition, short life cycle, and rapid reproduction, C. elegans has become a particularly useful tool in HTS methods for the discovery of NP bioactivity. Moreover, research on the C. elegans model is also developing daily with the effective support of modern technologies. Therefore, the C. elegans model will shortly become an effective tool to screen before conducting studies in mammalian animal models to provide sufficient scientific evidence for the efficacy and safety of natural compounds before preclinical and clinical trials. In addition, C. elegans can be a convenient and consumer-friendly experimental model for elucidating the molecular genetic mechanism underlying the bioactivity of popular commercial nutraceuticals with unclear modes of action, and dealing with animal ethical issues is not a problem. Establishing theories of the NP bioactivity and performing experimental verification with the C. elegans model will provide valuable information for NP science and technology.
Antimicrobial photodynamic therapy
Amyloid beta peptide (Aβ)
Green fluorescent protein
High-performance liquid chromatography
Liquid chromatography-tandem mass spectrometry
2-Methyl-6- (4-methoxyphenyl) -3,7-dihydroimidazo [1,2-a] pyrazin-3(7H)-one
Hydrogen peroxide sensor
Nuclear magnetic resonance
Reactive oxygen species
Kenyon C (1988) The nematode Caenorhabditis elegans. Science 240:1448–1453
Kaletta T, Hengartner MO (2006) Finding function in novel targets: C. elegans as a model organism. Nat Rev Drug Discov 5:387–398
Forslund K, Schreiber F, Thanintorn N, Sonnhammer EL (2011) OrthoDisease: tracking disease gene orthologs across 100 species. Brief Bioinform 12:463–473
Culetto E, Sattelle DB (2000) A role for Caenorhabditis elegans in understanding the function and interactions of human disease genes. Hum Mol Genet 9:869–877
Corsi AK, Wightman B, Chalfie M (2015) A transparent window into biology: a primer on Caenorhabditis elegans. Genetics 200:387–407
Kim Y, Park Y, Hwang J, Kwack K (2018) Comparative genomic analysis of the human and nematode Caenorhabditis elegans uncovers potential reproductive genes and disease associations in humans. Physiol Genomics 50:1002–1014
Byerly L, Cassada RC, Russell RL (1976) The life cycle of the nematode Caenorhabditis elegans. I. Wild-type growth and reproduction. Dev Biol 51:23–33
Strange K (2006) An overview of C. elegans biology. Methods Mol Biol 351:1–11
Kormish JD, Gaudet J, McGhee JD (2010) Development of the C. elegans digestive tract. Curr Opin Genet Dev 20:346–354
Johnson TE (2003) Advantages and disadvantages of Caenorhabditis elegans for aging research. Exp Gerontol 38:1329–1332
Consortium CeS (1998) Genome sequence of the nematode C. elegans: a platform for investigating biology. Science 282:2012–2018
Zhang S, Li F, Zhou T, Wang G, Li Z (2020) Caenorhabditis elegans as a useful model for studying aging mutations. Front Endocrinol 11:554994
Park HH, Jung Y, Lee SV (2017) Survival assays using Caenorhabditis elegans. Mol Cells 40:90–99
Puchalt JC, Layana Castro PE, Sánchez-Salmerón AJ (2020) Reducing results variance in lifespan machines: an analysis of the influence of vibrotaxis on wild-type Caenorhabditis elegans for the death criterion. Sensors 20:5981
Felker DP, Robbins CE, McCormick MA (2020) Automation of C. elegans lifespan measurement. Transl Med Aging 4:1–10
Puchalt JC, Sánchez-Salmerón AJ, Ivorra E, Llopis S, Martínez R, Martorell P (2021) Small flexible automated system for monitoring Caenorhabditis elegans lifespan based on active vision and image processing techniques. Sci Rep 11:12289
Lee SY, Kang K (2017) Measuring the effect of chemicals on the growth and reproduction of Caenorhabditis elegans. J Vis Exp 128:e56437
Lee SY, Kim JY, Jung YJ, Kang K (2017) Toxicological evaluation of the topoisomerase inhibitor, etoposide, in the model animal Caenorhabditis elegans and 3T3-L1 normal murine cells. Environ Toxicol 32:1836–1843
Partridge FA, Brown AE, Buckingham SD, Willis NJ, Wynne GM, Forman R, Else KJ, Morrison AA, Matthews JB, Russell AJ, Lomas DA, Sattelle DB (2018) An automated high-throughput system for phenotypic screening of chemical libraries on C. elegans and parasitic nematodes. Int J Parasitol Drugs Drug Resist 8:8–21
Wittkowski P, Marx-Stoelting P, Violet N, Fetz V, Schwarz F, Oelgeschläger M, Schönfelder G, Vogl S (2019) Caenorhabditis elegans as a promising alternative model for environmental chemical mixture effect assessment—a comparative study. Environ Sci Technol 53:12725–12733
Gjorgjieva J, Biron D, Haspel G (2014) Neurobiology of Caenorhabditis elegans locomotion: where do we stand? Bioscience 64:476–486
Lüersen K, Gottschling DC, Döring F (2016) Complex locomotion behavior changes are induced in Caenorhabditis elegans by the lack of the regulatory leak K+ channel TWK-7. Genetics 204:683–701
Ibáñez-Ventoso C, Herrera C, Chen E, Motto D, Driscoll M (2016) Automated analysis of C. elegans swim behavior using CeleST software. J Vis Exp 118:e54359
Lesanpezeshki L, Hewitt JE, Laranjeiro R, Antebi A, Driscoll M, Szewczyk NJ, Blawzdziewicz J, Lacerda CMR, Vanapalli SA (2019) Pluronic gel-based burrowing assay for rapid assessment of neuromuscular health in C. elegans. Sci Rep 9:15246
Blancas-Velazquez A, Mendoza J, Garcia AN, la Fleur SE (2017) Diet-induced obesity and circadian disruption of feeding behavior. Front Neurosci 11:23
Diomede L, Rognoni P, Lavatelli F, Romeo M, del Favero E, Cantù L, Ghibaudi E, di Fonzo A, Corbelli A, Fiordaliso F, Palladini G, Valentini V, Perfetti V, Salmona M, Merlini G (2014) A Caenorhabditis elegans-based assay recognizes immunoglobulin light chains causing heart amyloidosis. Blood 123:3543–3552
Hao L, Buttner EA (2014) Methods for studying the mechanisms of action of antipsychotic drugs in Caenorhabditis elegans. J Vis Exp 84:e50864
Kozlova AA, Lotfi M, Okkema PG (2019) Cross talk with the GAR-3 receptor contributes to feeding defects in Caenorhabditis elegans EAT-2 mutants. Genetics 212:231–243
Koelle MR, Horvitz HR (1996) EGL-10 regulates G protein signaling in the C. elegans nervous system and shares a conserved domain with many mammalian proteins. Cell 84:115–125
Gardner M, Rosell M, Myers EM (2013) Measuring the effects of bacteria on C. elegans behavior using an egg retention assay. J Vis Exp 80:e51203
Labuschagne CF, Brenkman AB (2013) Current methods in quantifying ROS and oxidative damage in Caenorhabditis elegans and other model organism of aging. Ageing Res Rev 12:918–930
Kang K, Jho EH, Lee HJ, Oidovsambuu S, Yun JH, Kim CY, Yoo JH, Kim YJ, Kim JH, Ahn SY, Nho CW (2011) Youngia denticulata protects against oxidative damage induced by tert-butylhydroperoxide in HepG2 cells. J Med Food 14:1198–1207
Hicks KA, Howe DK, Leung A, Denver DR, Estes S (2012) In vivo quantification reveals extensive natural variation in mitochondrial form and function in Caenorhabditis briggsae. PLoS ONE 7:e43837
Min H, Youn E, Shim YH (2020) Maternal caffeine intake disrupts eggshell integrity and retards larval development by reducing yolk production in a Caenorhabditis elegans model. Nutrients 12:1334
Fu X, Tang Y, Dickinson BC, Chang CJ, Chang Z (2015) An oxidative fluctuation hypothesis of aging generated by imaging H2O2 levels in live Caenorhabditis elegans with altered lifespans. Biochem Biophys Res Commun 458:896–900
Dikalov SI, Harrison DG (2014) Methods for detection of mitochondrial and cellular reactive oxygen species. Antioxid Redox Signal 20:372–382
Min H, Lee M, Cho KS, Lim HJ, Shim YH (2021) Nicotinamide supplementation improves oocyte quality and offspring development by modulating mitochondrial function in an aged Caenorhabditis elegans model. Antioxidants 10:519
Zhang G, Li Z, Chen F, Zhang D, Ji W, Yang Z, Wu Q, Zhang C, Li L, Huang W (2020) A novel fluorogenic probe for visualizing the hydrogen peroxide in Parkinson’s disease models. J Innov Opt Health Sci 13:2050013
Dickinson BC, Tang Y, Chang Z, Chang CJ (2011) A nuclear-localized fluorescent hydrogen peroxide probe for monitoring sirtuin-mediated oxidative stress responses in vivo. Chem Biol 18:943–948
He Y, Miao L, Yu L, Chen Q, Qiao Y, Zhang J-F, Zhou Y (2019) A near-infrared fluorescent probe for detection of exogenous and endogenous hydrogen peroxide in vivo. Dye Pigment 168:160–165
Jones KT, Ashrafi K (2009) Caenorhabditis elegans as an emerging model for studying the basic biology of obesity. Dis Model Mech 2:224–229
Escorcia W, Ruter DL, Nhan J, Curran SP (2018) Quantification of lipid abundance and evaluation of lipid distribution in Caenorhabditis elegans by Nile Red and Oil Red O staining. J Vis Exp 133:e57352
Yen K, Le TT, Bansal A, Narasimhan SD, Cheng JX, Tissenbaum HA (2010) A comparative study of fat storage quantitation in nematode Caenorhabditis elegans using label and label-free methods. PLoS ONE 5:e12810
Zhang SO, Trimble R, Guo F, Mak HY (2010) Lipid droplets as ubiquitous fat storage organelles in C. elegans. BMC Cell Biol 11:96
Brooks KK, Liang B, Watts JL (2009) The influence of bacterial diet on fat storage in C. elegans. PLoS ONE 4:e7545
Fam TK, Klymchenko AS, Collot M (2018) Recent advances in fluorescent probes for lipid droplets. Materials 11:1768
Ashrafi K, Chang FY, Watts JL, Fraser AG, Kamath RS, Ahringer J, Ruvkun G (2003) Genome-wide RNAi analysis of Caenorhabditis elegans fat regulatory genes. Nature 421:268–272
Mota AAR, Correa JR, de Andrade LP, Assumpção JAF, de Souza Cintra GA, Freitas-Junior LH, da Silva WA, de Oliveira HCB, Neto BAD (2018) From live cells to Caenorhabditis elegans: selective staining and quantification of lipid structures using a fluorescent hybrid benzothiadiazole derivative. ACS Omega 3:3874–3881
Goel A, Sharma A, Kathuria M, Bhattacharjee A, Verma A, Mishra PR, Nazir A, Mitra K (2014) New fluoranthene FLUN-550 as a fluorescent probe for selective staining and quantification of intracellular lipid droplets. Org Lett 16:756–759
Hobert O, Loria P (2006) Uses of GFP in Caenorhabditis elegans. Methods Biochem Anal 47:203–226
Braeckman BP, Smolders A, Back P, De Henau S (2016) In vivo detection of reactive oxygen species and redox status in Caenorhabditis elegans. Antioxid Redox Signal 25:577–592
Belousov VV, Fradkov AF, Lukyanov KA, Staroverov DB, Shakhbazov KS, Terskikh AV, Lukyanov S (2006) Genetically encoded fluorescent indicator for intracellular hydrogen peroxide. Nat Methods 3:281–286
Knoefler D, Thamsen M, Koniczek M, Niemuth NJ, Diederich AK, Jakob U (2012) Quantitative in vivo redox sensors uncover oxidative stress as an early event in life. Mol Cell 47:767–776
Koch K, Weldle N, Baier S, Büchter C, Wätjen W (2020) Hibiscus sabdariffa L. extract prolongs lifespan and protects against amyloid-β toxicity in Caenorhabditis elegans: involvement of the FoxO and Nrf2 orthologues DAF-16 and SKN-1. Eur J Nutr 59:137–150
Wang H, Zhang S, Zhai L, Sun L, Zhao D, Wang Z, Li X (2021) Ginsenoside extract from ginseng extends lifespan and health span in Caenorhabditis elegans. Food Funct 12:6793–6808
Duangjan C, Rangsinth P, Gu X, Zhang S, Wink M, Tencomnao T (2019) Glochidion zeylanicum leaf extracts exhibit lifespan extending and oxidative stress resistance properties in Caenorhabditis elegans via DAF-16/FoxO and SKN-1/Nrf-2 signaling pathways. Phytomedicine 64:153061
Zhuang JJ, Hunter CP (2012) RNA interference in Caenorhabditis elegans: uptake, mechanism, and regulation. Parasitology 139:560–573
Dudley NR, Labbé JC, Goldstein B (2002) Using RNA interference to identify genes required for RNA interference. Proc Natl Acad Sci USA 99:4191–4196
Maeda I, Kohara Y, Yamamoto M, Sugimoto A (2001) Large-scale analysis of gene function in Caenorhabditis elegans by high-throughput RNAi. Curr Biol 11:171–176
Kamath RS, Ahringer J (2003) Genome-wide RNAi screening in Caenorhabditis elegans. Methods 30:313–321
Jayarathne S, Ramalingam L, Edwards H, Vanapalli SA, Moustaid-Moussa N (2020) Tart cherry increases lifespan in caenorhabditis elegans by altering metabolic signaling pathways. Nutrients 12:1482
Zhao J, Zhu A, Sun Y, Zhang W, Zhang T, Gao Y, Shan D, Wang S, Li G, Zeng K, Wang Q (2020) Beneficial effects of sappanone A on lifespan and thermotolerance in Caenorhabditis elegans. Eur J Pharmacol 888:173558
Cordeiro M, Ribeiro ARC, de Melo LFM, da Silva LF, Fidelis GP, Silva LMP, Caland RBO, Cadavid COM, Aragão CFS, Zucolotto SM, Oliveira RP, Dos Santos D, Rocha HAO, Scortecci KC (2021) Antioxidant activities of Commiphora leptophloeos (Mart.) J. B. Gillett) (Burseraceae) leaf extracts using in vitro and in vivo assays. Oxid Med Cell Longev 2021:3043720
Kim JH, Bang IH, Noh YJ, Kim DK, Bae EJ, Hwang IH (2020) Metabolites produced by the oral commensal bacterium Corynebacterium durum extend the lifespan of Caenorhabditis elegans via SIR-2.1 overexpression. Int J Mol Sci 21:2212
Zhu Q, Qu Y, Zhou XG, Chen JN, Luo HR, Wu GS (2020) A Dihydroflavonoid Naringin extends the lifespan of C. elegans and delays the progression of aging-related diseases in PD/AD models via DAF-16. Oxid Med Cell Longev 2020:6069354
Dilberger B, Weppler S, Eckert GP (2021) Phenolic acid metabolites of polyphenols act as inductors for hormesis in C. elegans. Mech Ageing Dev 198:111518
Yu CW, Wei CC, Liao VH (2014) Curcumin-mediated oxidative stress resistance in Caenorhabditis elegans is modulated by age-1, akt-1, pdk-1, osr-1, unc-43, sek-1, skn-1, sir-2.1, and mev-1. Free Radic Res 48:371–379
Büchter C, Ackermann D, Havermann S, Honnen S, Chovolou Y, Fritz G, Kampkötter A, Wätjen W (2013) Myricetin-mediated lifespan extension in Caenorhabditis elegans is modulated by DAF-16. Int J Mol Sci 14:11895–11914
Cong W, Wang P, Qu Y, Tang J, Bai R, Zhao Y, Chunying C, Bi X (2015) Evaluation of the influence of fullerenol on aging and stress resistance using Caenorhabditis elegans. Biomaterials 42:78–86
Cuanalo-Contreras K, Park KW, Mukherjee A, Millán-Pérez Peña L, Soto C (2017) Delaying aging in Caenorhabditis elegans with protein aggregation inhibitors. Biochem Biophys Res Commun 482:62–67
Grünz G, Haas K, Soukup S, Klingenspor M, Kulling SE, Daniel H, Spanier B (2012) Structural features and bioavailability of four flavonoids and their implications for lifespan-extending and antioxidant actions in C. elegans. Mech Ageing Dev 133:1–10
Jung HY, Lee D, Ryu HG, Choi BH, Go Y, Lee N, Lee D, Son HG, Jeon J, Kim SH, Yoon JH, Park SM, Lee SV, Lee IK, Choi KY, Ryu SH, Nohara K, Yoo SH, Chen Z, Kim KT (2017) Myricetin improves endurance capacity and mitochondrial density by activating SIRT1 and PGC-1α. Sci Rep 7:6237
Wood JG, Rogina B, Lavu S, Howitz K, Helfand SL, Tatar M, Sinclair D (2004) Sirtuin activators mimic caloric restriction and delay ageing in metazoans. Nature 430:686–689
Park SK, Seong RK, Kim JA, Son SJ, Kim Y, Yokozawa T, Shin OS (2016) Oligonol promotes anti-aging pathways via modulation of SIRT1-AMPK-autophagy pathway. Nutr Res Pract 10:3–10
Xue J, Sheng X, Zhang BJ, Zhang C, Zhang G (2020) The Sirtuin-1 relied antioxidant and antiaging activity of 5,5′-diferulic acid glucoside esters derived from corn bran by enzymatic method. J Food Biochem 44:e13519
Luo S, Murphy CT (2011) Caenorhabditis elegans reproductive aging: regulation and underlying mechanisms. Genesis 49:53–65
McGee MD, Weber D, Day N, Vitelli C, Crippen D, Herndon LA, Hall DH, Melov S (2011) Loss of intestinal nuclei and intestinal integrity in aging C. elegans. Aging Cell 10:699–710
Hall DH, Winfrey VP, Blaeuer G, Hoffman LH, Furuta T, Rose KL, Hobert O, Greenstein D (1999) Ultrastructural features of the adult hermaphrodite gonad of Caenorhabditis elegans: relations between the germ line and soma. Dev Biol 212:101–123
Machado ML, Arantes LP, Gubert P, Zamberlan DC, da Silva TC, da Silveira TL, Boligon A, Soares FAA (2018) Ilex paraguariensis modulates fat metabolism in Caenorhabditis elegans through purinergic system (ADOR-1) and nuclear hormone receptor (NHR-49) pathways. PLoS ONE 13:e0204023
Rodrigues CF, Salgueiro W, Bianchini M, Veit JC, Puntel RL, Emanuelli T, Dernadin CC, Ávila DS (2018) Salvia hispanica L. (chia) seeds oil extracts reduce lipid accumulation and produce stress resistance in Caenorhabditis elegans. Nutr Metab 15:83
Lin C, Lin Y, Chen Y, Xu J, Li J, Cao Y, Su Z, Chen Y (2019) Effects of Momordica saponin extract on alleviating fat accumulation in Caenorhabditis elegans. Food Funct 10:3237–3251
Lin Y, Yang N, Bao B, Wang L, Chen J, Liu J (2020) Luteolin reduces fat storage in Caenorhabditis elegans by promoting the central serotonin pathway. Food Funct 11:730–740
Guerrero-Rubio MA, Hernández-García S, García-Carmona F, Gandía-Herrero F (2021) Flavonoids’ effects on Caenorhabditis elegans’ longevity, fat accumulation, stress resistance and gene modulation involve mTOR, SKN-1 and DAF-16. Antioxidants 10:438
Yue Y, Shen P, Chang AL, Qi W, Kim KH, Kim D, Park Y (2019) trans-Trismethoxy resveratrol decreased fat accumulation dependent on fat-6 and fat-7 in Caenorhabditis elegans. Food Funct 10:4966–4974
Roncato JFF, Camara D, Brussulo Pereira TC, Quines CB, Colomé LM, Denardin C, Haas S, Ávila DS (2019) Lipid reducing potential of liposomes loaded with ethanolic extract of purple pitanga (Eugenia uniflora) administered to Caenorhabditis elegans. J Liposome Res 29:274–282
Shen P, Zhang R, McClements DJ, Park Y (2019) Nanoemulsion-based delivery systems for testing nutraceutical efficacy using Caenorhabditis elegans: demonstration of curcumin bioaccumulation and body-fat reduction. Food Res Int 120:157–166
Zhu Y, Bai J, Zhou Y, Zhang Y, Zhao Y, Dong Y, Xiao X (2021) Water-soluble and alkali-soluble polysaccharides from bitter melon inhibited lipid accumulation in HepG2 cells and Caenorhabditis elegans. Int J Biol Macromol 166:155–165
Dimitriadi M, Hart AC (2010) Neurodegenerative disorders: insights from the nematode Caenorhabditis elegans. Neurobiol Dis 40:4–11
Prasanth MI, Brimson JM, Chuchawankul S, Sukprasansap M, Tencomnao T (2019) Antiaging, stress resistance, and neuroprotective efficacies of Cleistocalyx nervosum var. paniala fruit extracts using Caenorhabditis elegans model. Oxid Med Cell Longev 2019:7024785
Xie Z, Zhao J, Wang H, Jiang Y, Yang Q, Fu Y, Zeng H, Hölscher C, Xu J, Zhang Z (2020) Magnolol alleviates Alzheimer’s disease-like pathology in transgenic C. elegans by promoting microglia phagocytosis and the degradation of beta-amyloid through activation of PPAR-γ. Biomed Pharmacother 124:109886
Li H, Yu X, Li C, Ma L, Zhao Z, Guan S, Wang L (2021) Caffeic acid protects against Aβ toxicity and prolongs lifespan in Caenorhabditis elegans models. Food Funct 12:1219–1231
Selvaraj B, Nguyen UTT, Huh G, Nguyen DH, Mok IK, Lee H, Kang K, Bae AN, Kim DW, Lee JW (2020) Synthesis and biological evaluation of chalcone derivatives as neuroprotective agents against glutamate-induced HT22 mouse hippocampal neuronal cell death. Bioorg Med Chem Lett 30:127597
Johnson SL, Park HY, DaSilva NA, Vattem DA, Ma H, Seeram NP (2018) Levodopa-reduced mucuna pruriens seed extract shows neuroprotective effects against parkinson’s disease in murine microglia and human neuroblastoma cells, Caenorhabditis elegans, and Drosophila melanogaster. Nutrients 10:1139
Liu J, Banskota AH, Critchley AT, Hafting J, Prithiviraj B (2015) Neuroprotective effects of the cultivated Chondrus crispus in a C. elegans model of Parkinson’s disease. Mar Drugs 13:2250–2266
Cheon SM, Jang I, Lee MH, Kim DK, Jeon H, Cha DS (2017) Sorbus alnifolia protects dopaminergic neurodegeneration in Caenorhabditis elegans. Pharm Biol 55:481–486
Govindan S, Amirthalingam M, Duraisamy K, Govindhan T, Sundararaj N, Palanisamy S (2018) Phytochemicals-induced hormesis protects Caenorhabditis elegans against α-synuclein protein aggregation and stress through modulating HSF-1 and SKN-1/Nrf2 signaling pathways. Biomed Pharmacother 102:812–822
Malaiwong N, Chalorak P, Jattujan P, Manohong P, Niamnont N, Suphamungmee W, Sobhon P, Meemon K (2019) Anti-Parkinson activity of bioactive substances extracted from Holothuria leucospilota. Biomed Pharmacother 109:1967–1977
Brunetti G, Di Rosa G, Scuto M, Leri M, Stefani M, Schmitz-Linneweber C, Calabrese V, Saul N (2020) Healthspan maintenance and prevention of Parkinson’s-like phenotypes with hydroxytyrosol and oleuropein aglycone in C. elegans. Int J Mol Sci 21:2588
Goya ME, Xue F, Sampedro-Torres-Quevedo C, Arnaouteli S, Riquelme-Dominguez L, Romanowski A, Brydon J, Ball KL, Stanley-Wall NR, Doitsidou M (2020) Probiotic Bacillus subtilis protects against α-synuclein aggregation in C. elegans. Cell Rep 30:367–380
Le TAN, Selvaraj B, Lee JW, Kang K (2019) Measuring the effects of bacteria and chemicals on the intestinal permeability of Caenorhabditis elegans. J Vis Exp 154:e60419
Kim JY, Le TAN, Lee SY, Song DG, Hong SC, Cha KH, Lee JW, Pan CH, Kang K (2019) 3,3′-Diindolylmethane improves intestinal permeability dysfunction in cultured human intestinal cells and the model animal Caenorhabditis elegans. J Agric Food Chem 67:9277–9285
Han B, Sivaramakrishnan P, Lin CJ, Neve IAA, He J, Tay LWR, Sowa JN, Sizovs A, Du G, Wang J, Herman C, Wang MC (2017) Microbial genetic composition tunes host longevity. Cell 169:1249–1262
Pryor R, Norvaisas P, Marinos G, Best L, Thingholm LB, Quintaneiro LM, De Haes W, Esser D, Waschina S, Lujan C, Smith RL, Scott TA, Martinez-Martinez D, Woodward O, Bryson K, Laudes M, Lieb W, Houtkooper RH, Franke A, Temmerman L, Bjedov I, Cochemé HM, Kaleta C, Cabreiro F (2019) Host-microbe-drug-nutrient screen identifies bacterial effectors of metformin therapy. Cell 178:1299–1312
Park MR, Ryu S, Maburutse BE, Oh NS, Kim SH, Oh S, Jeong SY, Jeong DY, Oh S, Kim Y (2018) Probiotic Lactobacillus fermentum strain JDFM216 stimulates the longevity and immune response of Caenorhabditis elegans through a nuclear hormone receptor. Sci Rep 8:7441
Kamaladevi A, Balamurugan K (2016) Lactobacillus casei triggers a TLR mediated RACK-1 dependent p38 MAPK pathway in Caenorhabditis elegans to resist Klebsiella pneumoniae infection. Food Funct 7:3211–3223
Kim J, Moon Y (2019) Worm-based alternate assessment of probiotic intervention against gut barrier infection. Nutrients 11:2146
Kim JY, Lee SY, Jung SH, Kim MR, Choi ID, Lee JL, Sim JH, Pan CH, Kang K (2020) Protective effect of Lactobacillus casei HY2782 against particulate matter toxicity in human intestinal CCD-18Co cells and Caenorhabditis elegans. Biotechnol Lett 42:519–528
Patel P, Joshi C, Kothari V (2020) The anti-infective potential of hydroalcoholic extract of Phyllanthus emblica seeds against selected human-pathogenic bacteria. Infect Disord Drug Targets 20:672–692
Hao S, Yang D, Zhao L, Shi F, Ye G, Fu H, Lin J, Guo H, He R, Li J, Chen H, Khan MF, Li Y, Tang H (2021) EGCG-mediated potential inhibition of biofilm development and quorum sensing in Pseudomonas aeruginosa. Int J Mol Sci 22:4946
Anju VT, Busi S, Ranganathan S, Ampasala DR, Kumar S, Suchiang K, Kumavath R, Dyavaiah M (2021) Sesamin and sesamolin rescues Caenorhabditis elegans from Pseudomonas aeruginosa infection through the attenuation of quorum sensing regulated virulence factors. Microb Pathog 155:104912
Haripriyan J, Omanakuttan A, Menon ND, Vanuopadath M, Nair SS, Corriden R, Nair BG, Nizet V, Kumar GB (2018) Clove bud oil modulates pathogenicity phenotypes of the opportunistic human pathogen Pseudomonas aeruginosa. Sci Rep 8:3437
Peterson ND, Pukkila-Worley R (2018) Caenorhabditis elegans in high-throughput screens for anti-infective compounds. Curr Opin Immunol 54:59–65
Kong C, Tan MW, Nathan S (2014) Orthosiphon stamineus protects Caenorhabditis elegans against Staphylococcus aureus infection through immunomodulation. Biol Open 3:644–655
Yang J, Chen Z, Ching P, Shi Q, Li X (2013) An integrated microfluidic platform for evaluating in vivo antimicrobial activity of natural compounds using a whole-animal infection model. Lab Chip 13:3373–3382
Liu M, Kipanga P, Mai AH, Dhondt I, Braeckman BP, De Borggraeve W, Luyten W (2018) Bioassay-guided isolation of three anthelmintic compounds from Warburgia ugandensis Sprague subspecies ugandensis, and the mechanism of action of polygodial. Int J Parasitol 48:833–844
Li Z, Nair SK (2012) Quorum sensing: how bacteria can coordinate activity and synchronize their response to external signals? Protein Sci 21:1403–1417
Alexpandi R, Prasanth MI, Ravi AV, Balamurugan K, Durgadevi R, Srinivasan R, De Mesquita JF, Pandian SK (2019) Protective effect of neglected plant Diplocyclos palmatus on quorum sensing mediated infection of Serratia marcescens and UV-A induced photoaging in model Caenorhabditis elegans. J Photochem Photobiol B 201:111637
Subramenium GA, Swetha TK, Iyer PM, Balamurugan K, Pandian SK (2018) 5-hydroxymethyl-2-furaldehyde from marine bacterium Bacillus subtilis inhibits biofilm and virulence of Candida albicans. Microbiol Res 207:19–32
Scotti R, Stringaro A, Nicolini L, Zanellato M, Boccia P, Maggi F, Gabbianelli R (2021) Effects of essential oils from Cymbopogon spp. and Cinnamomum verum on biofilm and virulence properties of Escherichia coli O157:H7. Antibiotics 10:113
Dwivedi M, Muralidhar S, Saluja D (2020) Hibiscus sabdariffa extract inhibits adhesion, biofilm initiation and formation in Candida albicans. Indian J Microbiol 60:96–106
Kim Y, Lee JW, Kang SG, Oh S, Griffiths MW (2012) Bifidobacterium spp. influences the production of autoinducer-2 and biofilm formation by Escherichia coli O157:H7. Anaerobe 18:539–545
Lee KM, Lim J, Nam S, Yoon MY, Kwon YK, Jung BY, Park Y, Park S, Yoon SS (2011) Inhibitory effects of broccoli extract on Escherichia coli O157:H7 quorum sensing and in vivo virulence. FEMS Microbiol Lett 321:67–74
Choi EJ, Kim HI, Kim JA, Jun SY, Kang SH, Park DJ, Son SJ, Kim Y, Shin OS (2015) The herbal-derived honokiol and magnolol enhances immune response to infection with methicillin-sensitive Staphylococcus aureus (MSSA) and methicillin-resistant S. aureus (MRSA). Appl Microbiol Biotechnol 99:4387–4396
Polat E, Kang K (2021) Natural photosensitizers in antimicrobial photodynamic therapy. Biomedicines 9:584
Alam ST, Le TAN, Park JS, Kwon HC, Kang K (2019) Antimicrobial biophotonic treatment of ampicillin-resistant Pseudomonas aeruginosa with hypericin and ampicillin cotreatment followed by orange light. Pharmaceutics 11:641
Alam ST, Hwang H, Son JD, Nguyen UTT, Park JS, Kwon HC, Kwon J, Kang K (2021) Natural photosensitizers from Tripterygium wilfordii and their antimicrobial photodynamic therapeutic effects in a Caenorhabditis elegans model. J Photochem Photobiol B 218:112184
Moy TI, Conery AL, Larkins-Ford J, Wu G, Mazitschek R, Casadei G, Lewis K, Carpenter AE, Ausubel FM (2009) High-throughput screen for novel antimicrobials using a whole animal infection model. ACS Chem Biol 4:527–533
Ye X, Linton JM, Schork NJ, Buck LB, Petrascheck M (2014) A pharmacological network for lifespan extension in Caenorhabditis elegans. Aging Cell 13:206–215
Lucanic M, Garrett T, Yu I, Calahorro F, Asadi Shahmirzadi A, Miller A, Gill MS, Hughes RE, Holden-Dye L, Lithgow GJ (2016) Chemical activation of a food deprivation signal extends lifespan. Aging Cell 15:832–841
Taki AC, Byrne JJ, Boag PR, Jabbar A, Gasser RB (2021) Practical high-throughput method to screen compounds for anthelmintic activity against Caenorhabditis elegans. Molecules 26:4156
Zheng SQ, Ding AJ, Li GP, Wu GS, Luo HR (2013) Drug absorption efficiency in Caenorhbditis elegans delivered by different methods. PLoS ONE 8:e56877
Stupp GS, von Reuss SH, Izrayelit Y, Ajredini R, Schroeder FC, Edison AS (2013) Chemical detoxification of small molecules by Caenorhabditis elegans. ACS Chem Biol 8:309–313
Salzer L, Witting M (2021) Quo Vadis Caenorhabditis elegans metabolomics—a review of current methods and applications to explore metabolism in the nematode. Metabolites 11:284
Jones OA, Swain SC, Svendsen C, Griffin JL, Sturzenbaum SR, Spurgeon DJ (2012) Potential new method of mixture effects testing using metabolomics and Caenorhabditis elegans. J Proteome Res 11:1446–1453
Zhang X, Noguez JH, Zhou Y, Butcher RA (2013) Analysis of ascarosides from Caenorhabditis elegans using mass spectrometry and NMR spectroscopy. Methods Mol Biol 1068:71–92
Stasiuk SJ, MacNevin G, Workentine ML, Gray D, Redman E, Bartley D, Morrison A, Sharma N, Colwell D, Ro DK, Gilleard JS (2019) Similarities and differences in the biotransformation and transcriptomic responses of Caenorhabditis elegans and Haemonchus contortus to five different benzimidazole drugs. Int J Parasitol Drugs Drug Resist 11:13–29
Nguyen TTM, An YJ, Cha JW, Ko YJ, Lee H, Chung CH, Jeon SM, Lee J, Park S (2020) Real-time in-organism NMR metabolomics reveals different roles of AMP-activated protein kinase catalytic subunits. Anal Chem 92:7382–7387
Sarma GP, Lee CW, Portegys T, Ghayoomie V, Jacobs T, Alicea B, Cantarelli M, Currie M, Gerkin RC, Gingell S, Gleeson P, Gordon R, Hasani RM, Idili G, Khayrulin S, Lung D, Palyanov A, Watts M, Larson SD (2018) OpenWorm: overview and recent advances in integrative biological simulation of Caenorhabditis elegans. Philos Trans R Soc Lond B Biol Sci 373:20170382
Cao J, Guan G, Ho VWS, Wong MK, Chan LY, Tang C, Zhao Z, Yan H (2020) Establishment of a morphological atlas of the Caenorhabditis elegans embryo using deep-learning-based 4D segmentation. Nat Commun 11:6254
Xu JX, Deng X (2013) Biological modeling of complex chemotaxis behaviors for C. elegans under speed regulation—a dynamic neural networks approach. J Comput Neurosci 35:19–37
Martineau CN, Brown AEX, Laurent P (2020) Multidimensional phenotyping predicts lifespan and quantifies health in Caenorhabditis elegans. PLoS Comput Biol 16:e1008002
Fernandez-Moreno MA, Farr CL, Kaguni LS, Garesse R (2007) Drosophila melanogaster as a model system to study mitochondrial biology. Methods Mol Biol 372:33–49
Kishi S, Slack BE, Uchiyama J, Zhdanova IV (2009) Zebrafish as a genetic model in biological and behavioral gerontology: where development meets aging in vertebrates—a mini-review. Gerontology 55:430–441
Perlman RL (2016) Mouse models of human disease: an evolutionary perspective. Evol Med Public Health 2016:170–176
Lebedeva L, Zhumabayeva B, Gebauer T, Kisselev I, Aitasheva Z (2020) Zebrafish (Danio rerio) as a model for understanding the process of caudal fin regeneration. Zebrafish 17:359–372
Muschiol D, Schroeder F, Traunspurger W (2009) Life cycle and population growth rate of Caenorhabditis elegans studied by a new method. BMC Ecol 9:14
Zon LI (1999) Zebrafish: a new model for human disease. Genome Res 9:99–100
Lin SY, Craythorn RG, O’Connor AE, Matzuk MM, Girling JE, Morrison JR, de Kretser DM (2008) Female infertility and disrupted angiogenesis are actions of specific follistatin isoforms. Mol Endocrinol 22:415–429
Patton EE, Zon LI, Langenau DM (2021) Zebrafish disease models in drug discovery: from preclinical modelling to clinical trials. Nat Rev Drug Discov 20:611–628
Ero C, Gewaltig MO, Keller D, Markram H (2018) A cell atlas for the mouse brain. Front Neuroinform 12:84
Hinsch K, Zupanc GK (2007) Generation and long-term persistence of new neurons in the adult zebrafish brain: a quantitative analysis. Neuroscience 146:679–696
Scheffer LK, Xu CS, Januszewski M, Lu Z, Takemura SY, Hayworth KJ, Huang GB, Shinomiya K, Maitlin-Shepard J, Berg S, Clements J, Hubbard PM, Katz WT, Umayam L, Zhao T, Ackerman D, Blakely T, Bogovic J, Dolafi T, Kainmueller D, Kawase T, Khairy KA, Leavitt L, Li PH, Lindsey L, Neubarth N, Olbris DJ, Otsuna H, Trautman ET, Ito M, Bates AS, Goldammer J, Wolff T, Svirskas R, Schlegel P, Neace E, Knecht CJ, Alvarado CX, Bailey DA, Ballinger S, Borycz JA, Canino BS, Cheatham N, Cook M, Dreher M, Duclos O, Eubanks B, Fairbanks K, Finley S, Forknall N, Francis A, Hopkins GP, Joyce EM, Kim S, Kirk NA, Kovalyak J, Lauchie SA, Lohff A, Maldonado C, Manley EA, McLin S, Mooney C, Ndama M, Ogundeyi O, Okeoma N, Ordish C, Padilla N, Patrick CM, Paterson T, Phillips EE, Phillips EM, Rampally N, Ribeiro C, Robertson MK, Rymer JT, Ryan SM, Sammons M, Scott AK, Scott AL, Shinomiya A, Smith C, Smith K, Smith NL, Sobeski MA, Suleiman A, Swift J, Takemura S, Talebi I, Tarnogorska D, Tenshaw E, Tokhi T, Walsh JJ, Yang T, Horne JA, Li F, Parekh R, Rivlin PK, Jayaraman V, Costa M, Jefferis GS, Ito K, Saalfeld S, George R, Meinertzhagen IA, Rubin GM, Hess HF, Jain V, Plaza SM (2020) A connectome and analysis of the adult Drosophila central brain. Elife 9:e57443
White JG, Southgate E, Thomson JN, Brenner S (1986) The structure of the nervous system of the nematode Caenorhabditis elegans. Philos Trans R Soc Lond B Biol Sci 314:1–340
Zhou M, Diwu Z, Panchuk-Voloshina N, Haugland RP (1997) A stable nonfluorescent derivative of resorufin for the fluorometric determination of trace hydrogen peroxide: applications in detecting the activity of phagocyte NADPH oxidase and other oxidases. Anal Biochem 253:162–168
Zhao B, Summers FA, Mason RP (2012) Photooxidation of Amplex Red to resorufin: implications of exposing the Amplex Red assay to light. Free Radic Biol Med 53:1080–1087
Di Rosa G, Brunetti G, Scuto M, Trovato Salinaro A, Calabrese EJ, Crea R, Schmitz-Linneweber C, Calabrese V, Saul N (2020) Healthspan enhancement by olive polyphenols in C. elegans wild type and Parkinson’s models. Int J Mol Sci 21:3893
This work was supported by an intramural research grant from KIST (2E31311).
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Ha, N.M., Tran, S.H., Shim, YH. et al. Caenorhabditis elegans as a powerful tool in natural product bioactivity research. Appl Biol Chem 65, 18 (2022). https://doi.org/10.1186/s13765-022-00685-y
- Caenorhabditis elegans
- Gut health
- High-throughput screening
- Natural products