Counting Caenorhabditis elegans: Protocol Optimization and Applications for Population Growth and Toxicity Studies in Liquid Medium

Assessment of the effects of cannabidiol and a CBD-rich hemp extract in Caenorhabditis elegans

Consumer use of cannabidiol (CBD) is growing, but there are still data gaps regarding its possible adverse effects on reproduction and development. Multiple pathways and signaling cascades involved in organismal development and neuronal function, including endocannabinoid synthesis and signaling systems, are well conserved across phyla, suggesting that Caenorhabditis elegans can model the in vivo effects of exogenous cannabinoids. The effects in C. elegans on oxidative stress response (OxStrR), developmental timing, juvenile and adult spontaneous locomotor activity, reproductive output, and organismal CBD concentrations were assessed after exposure to purified CBD or a hemp extract suspended in 0.5% sesame oil emulsions. In C. elegans, this emulsion vehicle is equivalent to a high-fat diet (HFD). As in mammals, HFD was associated with oxidative-stress-related gene expression in C. elegans adults. CBD reduced HFD-induced OxStrR in transgenic adults and counteracted the hypoactivity observed in HFD-exposed wild-type adults. In C. elegans exposed to CBD from the onset of feeding, delays in later milestone acquisition were irreversible, while later juvenile locomotor activity effects were reversible after the removal of CBD exposure. CBD-induced reductions in mean juvenile population body size were cumulative when chronic exposures were initiated at parental reproductive maturity. Purified CBD was slightly more toxic than matched concentrations of CBD in hemp extract for all tested endpoints, and both were more toxic to juveniles than to adults. Dosimetry indicated that all adverse effect levels observed in C. elegans far exceeded recommended CBD dosages for humans.

Light-powered biodegradation of Imidacloprid by Scenedesmus sp. TXH202001: Assessing complete removal, metabolic pathways, and toxicity verification

Imidacloprid (IMI) is used extensively as an insecticide and poses a significant risk to both the ecological environment and human health. Biological methods are currently gaining recognition among the different strategies tested for wastewater treatment. This study focused on evaluating a recently discovered green alga, Scenedesmus sp. TXH202001, isolated from a municipal wastewater treatment plant (WWTP), exhibited notable capacity for IMI removal. After an 18-day evaluation, medium IMI concentrations (50 and 100 mg/L) facilitated the growth of microalgae whereas low (5 and 20 mg/L) and high (150 mg/L) concentrations had no discernible impact. No statistically significant disparities were detected in Fv/Fm, Malonaldehyde or Superoxide dismutase across all concentrations, suggesting Scenedesmus sp. TXH202001 exhibited notable resilience and adaptability to IMI conditions. Most notably, Scenedesmus sp. TXH202001 successfully eliminated > 99 % of IMI within 18 days subjected to IMI concentrations as high as 150 mg/L, which was contingent on the environmental factor of illumination. Molecular docking was used to identify the chemical reaction sites between IMI and typical degrading enzyme CYP450. Furthermore, the study revealed that the primary path for IMI removal was biodegradation and verified that the toxicity of the degraded product was lower than parent IMI in Caenorhabditis elegans. The efficacy of Scenedesmus sp. TXH202001 in wastewater was exceptional, thereby validating its practical utility.

The Importance of Biotinylation for the Suitability of Cationic and Neutral Fourth-Generation Polyamidoamine Dendrimers as Targeted Drug Carriers in the Therapy of Glioma and Liver Cancer

In this study, we hypothesized that biotinylated and/or glycidol-flanked fourth-generation polyamidoamine (PAMAM G4) dendrimers could be a tool for efficient drug transport into glioma and liver cancer cells. For this purpose, native PAMAM (G4) dendrimers, biotinylated (G4B), glycidylated (G4gl), and biotinylated and glycidylated (G4Bgl), were synthesized, and their cytotoxicity, uptake, and accumulation in vitro and in vivo were studied in relation to the transport mediated by the sodium-dependent multivitamin transporter (SMVT). The studies showed that the human temozolomide-resistant glioma cell line (U-118 MG) and hepatocellular carcinoma cell line (HepG2) indicated a higher amount of SMVT than human HaCaT keratinocytes (HaCaTs) used as a model of normal cells. The G4gl and G4Bgl dendrimers were highly biocompatible in vitro (they did not affect proliferation and mitochondrial activity) against HaCaT and U-118 MG glioma cells and in vivo (against Caenorhabditis elegans and Wistar rats). The studied compounds penetrated efficiently into all studied cell lines, but inconsistently with the uptake pattern observed for biotin and disproportionately for the level of SMVT. G4Bgl was taken up and accumulated after 48 h to the highest degree in glioma U-118 MG cells, where it was distributed in the whole cell area, including the nuclei. It did not induce resistance symptoms in glioma cells, unlike HepG2 cells. Based on studies on Wistar rats, there are indications that it can also penetrate the blood-brain barrier and act in the central nervous system area. Therefore, it might be a promising candidate for a carrier of therapeutic agents in glioma therapy. In turn, visualization with a confocal microscope showed that biotinylated G4B penetrated efficiently into the body of C. elegans, and it may be a useful vehicle for drugs used in anthelmintic therapy.

Application of 3Rs in Caenorhabditis elegans Research for the Identification of Health-Promoting Natural Products

The average age of the population is increasing worldwide, which has a profound impact on our society. This leads to an increasing demand for medicines and requires the development of new strategies to promote health during the additional years. In the search for resources and therapeutics for improved health during an extended life span, attention has to be paid to environmental exposure and ecosystem burdens that inevitably emerge with the extended consumption of medicines and drug development, even in the preclinical stage. The hereby introduced sustainable strategy for drug discovery is built on 3Rs, "R: obustness, R: eliability, and saving R: esources", inspired by both the 3Rs used in animal experiments and environmental protection, and centers on the usefulness and the variety of the small model organism Caenorhabditis elegans for detecting health-promoting natural products. A workflow encompassing a multilevel screening approach is presented to maximize the amount of information on health-promoting samples, while considering the 3Rs. A detailed, methodology- and praxis-oriented compilation and discussion of proposed C. elegans health span assays and more disease-specific assays are presented to offer guidance for scientists intending to work with C. elegans, thus facilitating the initial steps towards the integration of C. elegans assays in their laboratories.

Microbes are potential key players in the evolution of life histories and aging in Caenorhabditis elegans

Microbes can have profound effects on host fitness and health and the appearance of late-onset diseases. Host-microbe interactions thus represent a major environmental context for healthy aging of the host and might also mediate trade-offs between life-history traits in the evolution of host senescence. Here, we have used the nematode Caenorhabditis elegans to study how host-microbe interactions may modulate the evolution of life histories and aging. We first characterized the effects of two non-pathogenic and one pathogenic Escherichia coli strains, together with the pathogenic Serratia marcescens DB11 strain, on population growth rates and survival of C. elegans from five different genetic backgrounds. We then focused on an outbred C. elegans population, to understand if microbe-specific effects on the reproductive schedule and in traits such as developmental rate and survival were also expressed in the presence of males and standing genetic variation, which could be relevant for the evolution of C. elegans and other nematode species in nature. Our results show that host-microbe interactions have a substantial host-genotype-dependent impact on the reproductive aging and survival of the nematode host. Although both pathogenic bacteria reduced host survival in comparison with benign strains, they differed in how they affected other host traits. Host fertility and population growth rate were affected by S. marcescens DB11 only during early adulthood, whereas this occurred at later ages with the pathogenic E. coli IAI1. In both cases, these effects were largely dependent on the host genotypes. Given such microbe-specific genotypic differences in host life history, we predict that the evolution of reproductive schedules and senescence might be critically contingent on host-microbe interactions in nature.

Exploring the Potential of Lapatinib, Fulvestrant, and Paclitaxel Conjugated with Glycidylated PAMAM G4 Dendrimers for Cancer and Parasite Treatment

Fulvestrant (F), lapatinib (L), and paclitaxel (P) are hydrophobic, anticancer drugs used in the treatment of estrogen receptor (ER) and epidermal growth factor receptor (EGFR)-positive breast cancer. In this study, glycidylated PAMAM G4 dendrimers, substituted with F, L, and/or P and targeting tumor cells, were synthesized and characterized, and their antitumor activity against glioma U-118 MG and non-small cell lung cancer A549 cells was tested comparatively with human non-tumorogenic keratinocytes (HaCaT). All cell lines were ER+ and EGFR+. In addition, the described drugs were tested in the context of antinematode therapy on C. elegans. The results show that the water-soluble conjugates of G4P, G4F, G4L, and G4PFL actively entered the tested cells via endocytosis due to the positive zeta potential (between 13.57-40.29 mV) and the nanoparticle diameter of 99-138 nm. The conjugates of G4P and G4PFL at nanomolar concentrations were the most active, and the least active conjugate was G4F. The tested conjugates inhibited the proliferation of HaCaT and A549 cells; in glioma cells, cytotoxicity was associated mainly with cell damage (mitochondria and membrane transport). The toxicity of the conjugates was proportional to the number of drug residues attached, with the exception of G4L; its action was two- and eight-fold stronger against glioma and keratinocytes, respectively, than the equivalent of lapatinib alone. Unfortunately, non-cancer HaCaT cells were the most sensitive to the tested constructs, which forced a change in the approach to the use of ER and EGFR receptors as a goal in cancer therapy. In vivo studies on C. elegans have shown that all compounds, most notably G4PFL, may be potentially useful in anthelmintic therapy.

Evidence for Complex Interplay between Quorum Sensing and Antibiotic Resistance in Pseudomonas aeruginosa

Quorum sensing (QS) is a cell-density-dependent, intercellular communication system mediated by small diffusible signaling molecules. QS regulates a range of bacterial behaviors, including biofilm formation, virulence, drug resistance mechanisms, and antibiotic tolerance. Enzymes capable of degrading signaling molecules can interfere in QS-a process termed as quorum quenching (QQ). Remarkably, previous work reported some cases where enzymatic interference in QS was synergistic to antibiotics against Pseudomonas aeruginosa. The premise of combination therapy is attractive to fight against multidrug-resistant bacteria, yet comprehensive studies are lacking. Here, we evaluate the effects of QS signal disruption on the antibiotic resistance profile of P. aeruginosa by testing 222 antibiotics and antibacterial compounds from 15 different classes. We found compelling evidence that QS signal disruption does indeed affect antibiotic resistance (40% of all tested compounds; 89/222), albeit not always synergistically (not synergistic for 19% of compounds; 43/222). For some tested antibiotics, such as sulfathiazole and trimethoprim, we were able to relate the changes in resistance caused by QS signal disruption to the modulation of the expression of key genes of the folate biosynthetic pathway. Moreover, using a P. aeruginosa-based Caenorhabditis elegans killing model, we confirmed that enzymatic QQ modulates the effects of antibiotics on P. aeruginosa's pathogenicity in vivo. Altogether, these results show that signal disruption has profound and complex effects on the antibiotic resistance profile of P. aeruginosa. This work suggests that combination therapy including QQ and antibiotics should be discussed not globally but, rather, in case-by-case studies. IMPORTANCE Quorum sensing (QS) is a cell-density-dependent communication system used by a wide range of bacteria to coordinate behaviors. Strategies pertaining to the interference in QS are appealing approaches to control microbial behaviors that depend on QS, including virulence and biofilms. Interference in QS was previously reported to be synergistic with antibiotics, yet no systematic assessment exists. Here, we evaluate the potential of combination treatments using the model opportunistic human pathogen Pseudomonas aeruginosa PA14. In this model, collected data demonstrate that QS largely modulates the antibiotic resistance profile of PA14 (for more than 40% of the tested drugs). However, the outcome of combination treatments is synergistic for only 19% of them. This research demonstrates the complex relationship between QS and antibiotic resistance and suggests that combination therapy including QS inhibitors and antibiotics should be discussed not globally but, rather, in case-by-case studies.

Development of a 96-Well Electrophilic Allergen Screening Assay for Skin Sensitization Using a Measurement Science Approach

The Electrophilic Allergen Screening Assay (EASA) has emerged as a promising in chemico method to detect the first key event in the adverse outcome pathway (AOP) for skin sensitization. This assay functions by assessing the depletion of one of two probe molecules (4-nitrobenzenethiol (NBT) and pyridoxylamine (PDA)) in the presence of a test compound (TC). The initial development of EASA utilized a cuvette format resulting in multiple measurement challenges such as low throughput and the inability to include adequate control measurements. In this study, we describe the redesign of EASA into a 96-well plate format that incorporates in-process control measurements to quantify key sources of variability each time the assay is run. The data from the analysis of 67 TCs using the 96-well format had 77% concordance with animal data from the local lymph node assay (LLNA), a result consistent with that for the direct peptide reactivity assay (DPRA), an OECD test guideline (442C) protein binding assay. Overall, the measurement science approach described here provides steps during assay development that can be taken to increase confidence of in chemico assays by attempting to fully characterize the sources of variability and potential biases and incorporate in-process control measurements into the assay.

Spatiotemporal bio-shielding of bacteria through consolidated geometrical structuring

The probiotic bacterium Lactobacillus plantarum is often reckoned as a ‘generalist’ for its ability to adapt and survive in diverse ecological niches. The genomic signatures of L. plantarum have shown its intricate evolutionary ancestry and dynamic lifestyles. Here, we report on a unique geometrical arrangement of the multicellular population of L. plantarum cells. Prominently, a phenomenon of the cone-shaped colony formation and V-shaped cell chaining are discovered in response to the acidic-pH environment. Moreover, subsequent cold stress response triggers an unusual cellular arrangement of consolidated bundles, which appeared to be independently governed by a small heat shock protein (HSP 1). We further report that the V-shaped L. plantarum chaining demonstrates potent antagonistic activity against Candida albicans, a pathogenic yeast, both in vitro and in a Caenorhabditis elegans co-infection model. Finally, we deduce that the multifaceted traits manifested by this probiotic bacterium is an outcome of its dynamic flexibility and cellular heterogeneity.

The Bacillary Postbiotics, Including 2-Undecanone, Suppress the Virulence of Pathogenic Microorganisms

Secreted molecules from probiotic Bacilli have often been considered potential pharmaceuticals to fight infections caused by bacterial or yeast pathogens. In the present study, we investigated the antagonistic potential of secreted probiotic filtrates (hereafter, postbiotics) derived from Lactobacillus plantarum cells against pathogenic microorganisms, such as Escherichia coli, Staphylococcus aureus, and Candida albicans. We found that the postbiotics mitigate the biofilms of the tested pathogens with no notable effect on their planktonic growth. In addition, the postbiotics suppressed some virulence traits, for instance, the dendrite swarming motility of E. coli and yeast-to-hyphal switch in C. albicans. Further assays with an active constituent produced by the L. plantarum cells–2-undecanone revealed two significant findings: (i) 2-undecanone inhibits C. albicans biofilms and hyphae in vitro and in a Caenorhabditis elegans model, and (ii) it interacts specifically with Gln 58 amino acid residue of hyphal wall protein-1 (Hwp-1) in molecular docking analysis. The results suggest the targeted mode of antagonistic action of 2-undecanone against C. albicans biofilm. In total, the findings of the study depict an appealing strategy to use postbiotics, including specific ketone molecules, produced by L. plantarum for developing novel antibiofilm and anti-hyphal pharmaceuticals.

Biotin Transport-Targeting Polysaccharide-Modified PAMAM G3 Dendrimer as System Delivering α-Mangostin into Cancer Cells and C. elegans Worms

The natural xanthone α-mangostin (αM) exhibits a wide range of pharmacological activities, including antineoplastic and anti-nematode properties, but low water solubility and poor selectivity of the drug prevent its potential clinical use. Therefore, the targeted third-generation poly(amidoamine) dendrimer (PAMAM G3) delivery system was proposed, based on hyperbranched polymer showing good solubility, high biocompatibility and low immunogenicity. A multifunctional nanocarrier was prepared by attaching αM to the surface amine groups of dendrimer via amide bond in the ratio 5 (G3^2B12gh5M) or 17 (G3^2B10gh17M) residues per one dendrimer molecule. Twelve or ten remaining amine groups were modified by conjugation with D-glucoheptono-1,4-lactone (gh) to block the amine groups, and two biotin (B) residues as targeting moieties. The biological activity of the obtained conjugates was studied in vitro on glioma U-118 MG and squamous cell carcinoma SCC-15 cancer cells compared to normal fibroblasts (BJ), and in vivo on a model organism Caenorhabditis elegans. Dendrimer vehicle G3^2B12gh at concentrations up to 20 µM showed no anti-proliferative effect against tested cell lines, with a feeble cytotoxicity of the highest concentration seen only with SCC-15 cells. The attachment of αM to the vehicle significantly increased cytotoxic effect of the drug, even by 4- and 25-fold for G3^2B12gh5M and G3^2B10gh17M, respectively. A stronger inhibition of cells viability and influence on other metabolic parameters (proliferation, adhesion, ATP level and Caspase-3/7 activity) was observed for G3^2B10gh17M than for G3^2B12gh5M. Both bioconjugates were internalized efficiently into the cells. Similarly, the attachment of αM to the dendrimer vehicle increased its toxicity for C. elegans. Thus, the proposed α-mangostin delivery system allowed the drug to be more effective in the dendrimer-bound as compared to free state against both cultured the cancer cells and model organism, suggesting that this treatment is promising for anticancer as well as anti-nematode chemotherapy.

Risperidone induced alterations in feeding and locomotion behavior of Caenorhabditis elegans

Antipsychotic drugs (APDs) are prescribed for the treatment of psychiatric illness. However, these drugs can also contribute to several developmental and behavioral disorders. Contemporary studies to evaluate the toxic effects of numerous atypical antipsychotics are reported to cause behavioral alteration at variable doses in mammals and nematodes. Risperidone, the second most prescribed drug in India, requires more exploration of its adverse effects on humans. Here, we explore effects on feeding behavior and locomotion patterns due to risperidone exposure in C. elegans model. The study targets to work out the toxic effects of risperidone exposure on feeding and locomotion behavior in addition to the expected pharmacological effects. N2 wild type strain was exposed in liquid culture assay for 2, 4, 6, 8, 10, and 12 hours with fixed 50 µM concentration. Feeding behavior was depleted due to inhibition in pharyngeal pumping varying from 11.05% - 45.67% in a time-dependent manner. Results of locomotion assay also show time-varying increase in reversals (4.9%-34.03%) and omega bends (26.23%-62.17%) with reduction in turn counts (29.07%- 42.2%) and peristaltic speed (31.38%-42.22%) amongst exposed groups as to control. The present work shows behavioral alterations due to risperidone exposure (50 µM) in C. elegans is in a time-dependent manner. The study concludes that risperidone exposure in C. elegans produces toxic effects with time, possibly caused by antagonizing other receptors apart from serotonin (5-H2T) and dopamine (D2) adding to its expected pharmacological effects.

Investigation of anthelmintic activity of the acetone extract and constituents of Typha capensis against animal parasitic Haemonchus contortus and free-living Caenorhabditis elegans

This study aimed to determine in vitro anthelmintic activity of plant extracts of eleven plant species used traditionally in South Africa to treat various disorders including symptoms related to nematode infections, and to isolate bioactive compounds from the most active plant extract. Crude plant extracts were tested on different life-cycle stages of Haemonchus contortus. The cytotoxicity of the most active extracts, fractions and compounds was evaluated on Vero cells and the most potent extract, fractions and compounds were tested for their ability to kill the parasitic H. contortus and the free-living nematode Caenorhabditis elegans. Typha capensis acetone extract had the strongest egg hatching inhibitory effect with an EC₅₀ of 184.94 μg/mL, and this extract also halted larval development of H. contortus with an EC₅₀ of 83.30 μg/mL compared to the positive control (albendazole) with an EC₅₀ of 2.66 μg/mL. Typha capensis crude extract and its butanol fraction had promising anthelmintic activity against both parasitic H. contortus and free-living C. elegans. Two compounds isolated from T. capensis, namely, isorhamnetin-3-O-β-D-glucoside and isorhamnetin 3-O-rutinoside, had antioxidant activity with IC₅₀ values of 3.16 μg/mL and 0.96 μg/mL respectively, and good anthelmintic activity against H. contortus with IC₅₀ values of 55.61 μg/mL and 145.17 μg/mL respectively. Identification of bioactive compounds from the T. capensis crude extract supports development of this extract as a complementary or alternative treatment against haemonchosis. However, further research is necessary to confirm the anthelmintic efficacy of the plant, including in vivo studies.

Combining secondary ion mass spectrometry image depth profiling and single particle inductively coupled plasma mass spectrometry to investigate the uptake and biodistribution of gold nanoparticles in Caenorhabditis elegans

Analytical techniques capable of determining the spatial distribution and quantity (mass and/or particle number) of engineered nanomaterials in organisms are essential for characterizing nano-bio interactions and for nanomaterial risk assessments. Here, we combine the use of dynamic secondary ion mass spectrometry (dynamic SIMS) and single particle inductively coupled mass spectrometry (spICP-MS) techniques to determine the biodistribution and quantity of gold nanoparticles (AuNPs) ingested by Caenorhabditis elegans. We report the application of SIMS in image depth profiling mode for visualizing, identifying, and characterizing the biodistribution of AuNPs ingested by nematodes in both the lateral and z (depth) dimensions. In parallel, conventional- and sp-ICP-MS quantified the mean number of AuNPs within the nematode, ranging from 2 to 36 NPs depending on the size of AuNP. The complementary data from both SIMS image depth profiling and spICP-MS provides a complete view of the uptake, translocation, and size distribution of ingested NPs within Caenorhabditis elegans.

Ecotoxicity Risk of Low-Dose Methylmercury Exposure to Caenorhabditis elegans: Multigenerational Toxicity and Population Discrepancy

Methylmercury (MeHg) is a common organic form of mercury in water, which has been linked to several forms of biological toxicity. However, studies on the ecotoxicity risk of long-term exposure to low-dose MeHg are insufficient for the assessment of environmental safety. In the present study, the effects of MeHg on multiple generations (P0-F3) and population of Caenorhabditis elegans were investigated under long-term, low-dose exposure. We investigated the multigenerational toxicity of MeHg by analyzing reproductive and developmental indicators. According to our results, exposure to 100 nM MeHg had little effect on the parental generation (P0) but caused serious reproductive toxicity in the offspring (F1-F3), and the effect of MeHg was aggravated with each passing generation. The genes related to apoptosis and DNA damage were upregulated in the F3 generation. Pearson correlation analysis showed that the changes in these genes were closely related to the apoptosis of gonadal cells. Furthermore, chronic exposure to MeHg (from 100 to 1000 nM group) caused a sharp decline in population size and triggered the "bag of worms" phenotype. Genes related to vulvar development were downregulated in the F3 generation after treatment with 100 nM MeHg. These data suggest that long-term low-dose MeHg exposure adversely affected C. elegans and its offspring and triggered multigenerational toxicity and population discrepancy.

Molecular and cellular responses to short exposure to bisphenols A, F, and S and eluates of microplastics in C. elegans

Bisphenol F (BPF) and bisphenol S (BPS) have been developed as an alternative to bisphenol A (BPA), a well-known endocrine disruptor, leading to their detection in the aquatic environment. In this work, we used the animal model Caenorhabditis elegans to improve our understanding of their potential effects on the biota and the environment. Our findings demonstrated that, after 24 h exposure, all the bisphenols examined increased the number of apoptotic corpses and the expression of the detoxifying enzymes SOD-3 and GST-4, without affecting the ROS levels, while BPA and BPS significantly enhanced DNA fragmentation. Furthermore, similarly to BPA, BPF and BPS did not alter the lifespan through the activation of SEK-1 and SKN-1 pathways. Thus, this study raises the attention of the risks associated with exposure to BPA alternatives. We also examined the effects of microplastic (MP) eluates on C. elegans. Aqueous extracts of weathered microplastic samples, both at high and low degradation state and pellets, have been evaluated for their effects on lifespan, DNA fragmentation, germline apoptosis, and oxidative stress response. Overall, our findings showed that eluates of low degraded plastics exert a greater toxic effect on the nematode C. elegans compared with the aqueous sample of high degraded plastic fragments and pellets.

A quantitative medium-throughput assay to measure Caenorhabditis elegans development and reproduction

Growth and offspring count are two commonly determined toxicological endpoints for chemical- or gene-induced developmental and reproductive effects in Caenorhabditis elegans. Here, we present a protocol for a 96 h, medium-throughput assay, assessing both endpoints quantitatively within an automated framework using open-source software. The assay utilizes whole 96-well fluorescence images taken with a high-content screening system. Alternatively, conventional fluorescence images can also be utilized with only a few adjustments.

For complete details on the use and execution of this protocol, please refer to Wittkowski et al. (2019).

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A medium-throughput assay to determine C. elegans growth and offspring count

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Applicable to high-content screening and conventional fluorescence microscopy

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Automated data acquisition and processing with open-source software

Neonicotinoid-containing insecticide disruption of growth, locomotion, and fertility in Caenorhabditis elegans

Neonicotinoids, a class of insecticides structurally similar to nicotine that target biting and sucking insects, are the most widely used insecticides today, in part due to their supposed low toxicity in other organisms. However, a growing body of research has found that even low doses of neonicotinoids can induce unexpected negative effects on the physiology and survival of a wide range of non-target organisms. Importantly, no work has been done on the commercial formulations of pesticides that include imidacloprid as the active ingredient, but that also contain many other components. The present study examines the sublethal effects of "Tree and Shrub"™ ("T+S"), a commercial insecticide containing the neonicotinoid imidacloprid as its active ingredient, on Caenorhabditis elegans. We discovered that "T+S" significantly stunted the overall growth in wildtype nematodes, an effect that was exacerbated by concurrent exposure to heat stress. "T+S" also negatively impacted fecundity as measured by increased germline apoptosis, a decrease in egg-laying, and fewer viable offspring. Lastly, exposure to "T+S" resulted in degenerative changes in nicotinic cholinergic neurons in wildtype nematodes. As a whole, these findings demonstrate widespread toxic effects of neonicotinoids to critical functions in nematodes.

Celecoxib substituted biotinylated poly(amidoamine) G3 dendrimer as potential treatment for temozolomide resistant glioma therapy and anti-nematode agent

Glioblastoma multiforme (GBM) is a one of the most widely diagnosed and difficult to treat type of central nervous system tumors. Resection combined with radiotherapy and temozolomide (TMZ) chemotherapy prolongs patients' survival only for 12 - 15 months after diagnosis. Moreover, many patients develop TMZ resistance, thus important is search for a new therapy regimes including targeted drug delivery. Most types of GBM reveal increased expression of cyclooxygenase-2 (COX-2) and production of prostaglandin E2 (PGE₂), that are considered as valuable therapeutic target. In these studies, the anti-tumor properties of the selective COX-2 inhibitor celecoxib (CXB) and biotinylated third generation of the poly(amidoamine) dendrimer substituted with 31 CXB residues (G3BC31) on TMZ -resistant U-118 MG glioma cell line were examined and compared with the effect of TMZ alone including viability, proliferation, migration and apoptosis, as well as the cellular expression of COX-2, ATP level, and PGE₂ production. Confocal microscopy analysis with the fluorescently labeled G3BC31 analogue has shown that the compound was effectively accumulated in U-118 MG cells in time-dependent manner and its localization was confirmed in lysosomes but not nuclei. G3BC31 reveal much higher cytotoxicity for U-118 MG cells at relatively low concentrations in the range of 2-4 µM with compared to CBX alone, active at 50-100 µM. This was due to induction of apoptosis and inhibition of proliferation and migration. Observed effects were concomitant with reduction of PGE₂ production but independent of COX-2 expression. We suggest that investigated conjugate may be a promising candidate for therapy of TMZ-resistant glioblastoma multiforme, although applicable in local treatment, since our previous study of G3BC31 did not demonstrate selectivity against glioma cells compared to normal human fibroblasts. However, it has to be pointed that in our in vivo studies conducted with model organism, Caenorhabditis elegans indicated high anti-nematode activity of G3BC31 in comparison with CXB alone that confirms of usefulness of that organism for estimation of anti-cancer drug toxicity.

Caenorhabditis elegans, a Host to Investigate the Probiotic Properties of Beneficial Microorganisms

Caenorhabditis elegans, a non-parasitic nematode emerges as a relevant and powerful candidate as an in vivo model for microorganisms-microorganisms and microorganisms-host interactions studies. Experiments have demonstrated the probiotic potential of bacteria since they can provide to the worm a longer lifespan, an increased resistance to pathogens and to oxidative or heat stresses. Probiotics are used to prevent or treat microbiota dysbiosis and associated pathologies but the molecular mechanisms underlying their capacities are still unknown. Beyond safety and healthy aspects of probiotics, C. elegans represents a powerful way to design large-scale studies to explore transkingdom interactions and to solve questioning about the molecular aspect of these interactions. Future challenges and opportunities would be to validate C. elegans as an in vivo tool for high-throughput screening of microorganisms for their potential probiotic use on human health and to enlarge the panels of microorganisms studied as well as the human diseases investigated.

A robust and miniaturized screening platform to study natural products affecting metabolism and survival in Caenorhabditis elegans

In this study a robust, whole organism screening based on Caenorhabditis elegans is presented for the discovery of natural products (NP) with beneficial effects against obesity and age-related diseases. Several parameters of the elaborated workflow were optimized to be adapted for probing multicomponent mixtures combining knowledge from traditional medicine and NP chemistry by generating optimized small-scale extracts considering scarcity of the natural source, solubility issues, and potential assay interferences. The established miniaturized assay protocol allows for in vivo probing of small amounts of even complex samples (~ 1 mg) to test their ability to increase the nematodes' survival time and the suppression of fat accumulation assessed by Nile red staining as hall marks of "healthy aging". The workflow was applied on 24 herbal and fungal materials traditionally used against symptoms of the metabolic syndrome and revealed promising results for the extracts of Gardenia jasminoides fruits and the sclerotia from Inonotus obliquus. Tested at 100 µg/mL they were able to significantly reduce the Nile red fluorescence and extend the 50% survival rate (DT50) compared to the control groups. This phenotype-directed in vivo approach opens up new horizons for the selection of natural starting materials and the investigation of their active principles as fast drug discovery tool with predictive value for human diseases.

Emerging Standards and Analytical Science for Nanoenabled Medical Products

Development and application of nanotechnology-enabled medical products, including drugs, devices, and in vitro diagnostics, are rapidly expanding in the global marketplace. In this review, the focus is on providing the reader with an introduction to the landscape of commercially available nanotechnology-enabled medical products as well as an overview of the international documentary standards and reference materials that support and facilitate efficient regulatory evaluation and reliable manufacturing of this diverse group of medical products. We describe the materials, test methods, and standards development needs for emerging medical products. Scientific and measurement challenges involved in the development and application of innovative nanoenabled medical products motivate discussion throughout this review.

Oxygen consumption rate of Caenorhabditis elegans as a high-throughput endpoint of toxicity testing using the Seahorse XFe96 Extracellular Flux Analyzer

Caenorhabditis elegans presents functioning, biologically relevant phenotypes and is frequently used as a bioindicator of toxicity. However, most C. elegans in vivo effect-assessment methods are laborious and time consuming. Therefore, we developed a novel method to measure the oxygen consumption rate of C. elegans as a sublethal endpoint of toxicity. This protocol was tested by exposing 50 larval stage one C. elegans individuals for 48 h (at 20 °C) to different concentrations of two toxicants i.e. benzylcetyldimethylammonium chloride (BAC-C16) and cadmium (Cd). Following exposures, the oxygen consumption rate of the C. elegans individuals were measured using the high-throughput functionality of the Seahorse XFe96 Extracellular Flux Analyzer. Dose-response curves for BAC-C16 (R2 = 0.93; P = 0.001) and Cd (R2 = 0.98; P = 0.001) were created. Furthermore, a strong, positive correlation was evidenced between C. elegans oxygen consumption rate and a commonly used, ecologically relevant endpoint of toxicity (growth inhibition) for BAC-C16 (R2 = 0.93; P = 0.0001) and Cd (R2 = 0.91; P = 0.0001). The data presented in this study show that C. elegans oxygen consumption rate can be used as a promising functional measurement of toxicity.

Measurement of Oxidatively Induced DNA Damage in Caenorhabditis elegans with High-Salt DNA Extraction and Isotope-Dilution Mass Spectrometry

Caenorhabditis elegans is used extensively as a medical and toxicological model organism. However, little is known about background levels of oxidatively induced DNA damage in the nematode or how culturing methods affect DNA damage levels. The tough C. elegans cuticle makes it challenging to extract genomic DNA without harsh procedures that can artifactually increase DNA damage. Therefore, a mild extraction protocol based on enzymatic digestion of the C. elegans cuticle with high-salt phase-separation of DNA has been developed and optimized. This method allows for efficient extraction of >50 μg DNA using a minimum of 250000 nematodes grown in liquid culture. The extracted DNA exhibited acceptable RNA levels (<10% contamination), functionality in polymerase chain reaction assays, and reproducible DNA fragmentation. Gas chromatography/tandem mass spectrometry (GC-MS/MS) with isotope-dilution measured lower lesion levels in high-salt extracts than in phenol extracts. Phenolic extraction produced a statistically significant increase in 8-hydroxyguanine, a known artifact, and additional artifactual increases in 2,6-diamino-4-hydroxy-5-formamidopyrimidine, 4,6-diamino-5-formamidopyrimidine, and 8-hydroxyadenine. The high-salt DNA extraction procedure utilizes green solvents and reagents and minimizes artifactual DNA damage, making it more suitable for molecular and toxicological studies in C. elegans. This is, to our knowledge, the first use of GC-MS/MS to measure multiple 8,5'-cyclopurine-2'-deoxynucleosides in a toxicologically important terrestrial organism.

Dual Inhibition of Klebsiella pneumoniae and Pseudomonas aeruginosa Iron Metabolism Using Gallium Porphyrin and Gallium Nitrate

Iron- and heme-uptake pathways and metabolism are promising targets for the development of new antimicrobial agents, as their disruption would lead to nutritional iron starvation and inhibition of bacterial growth. Salts of gallium(III) (Ga), an iron mimetic metal, disrupt iron-dependent biological processes by binding iron-utilizing proteins and competing with iron for uptake by bacterial siderophore-mediated iron uptake systems. Ga porphyrins, heme mimetic complexes, disrupt heme-utilizing hemoproteins. Because Ga(NO₃)₃ and Ga porphyrin disrupt different pathways of bacterial ion acquisition and utilization, we hypothesized that if used in combination, they would result in enhanced antimicrobial activity. Antimicrobial activity of Ga porphyrins (Ga protoporphyrin, GaPP, or Ga mesoporphyrin, GaMP) alone and in combination with Ga(NO₃)₃ were evaluated against Pseudomonas aeruginosa, Klebsiella pneumoniae, Acinetobacter baumannii, and methicillin-resistant Staphylococcus aureus (MRSA) under iron-limited conditions. The Ga porphyrin/Ga(NO₃)₃ combination demonstrated substantial synergism against K. pneumoniae, P. aeruginosa, and MRSA. Time-kill assays revealed that the synergistic combination of GaPP/Ga(NO₃)₃ was bacteriostatic against K. pneumoniae and MRSA and bactericidal against P. aeruginosa. The GaPP/Ga(NO₃)₃ combination significantly disrupted K. pneumoniae and P. aeruginosa biofilms on plasma-coated surfaces and increased the survival of Caenorhabditis elegans infected with K. pneumoniae or P. aeruginosa. When assessing the antibacterial activity of the Ga(III)/antibiotic combinations, GaPP/colistin and Ga(NO₃)₃/colistin combinations also showed synergistic activity against K. pneumoniae and P. aeruginosa. Our results demonstrate that GaPP and Ga(NO₃)₃ have significant synergistic effects against several important human bacterial pathogens through dual inhibition of iron and heme metabolism.

De novo transcriptome assembly of a facultative parasitic nematode Pelodera (syn. Rhabditis) strongyloides

Pelodera strongyloides is a generally free-living gonochoristic facultative nematode. The whole genomic sequence of P. strongyloides remains unknown but 4 small subunit ribosomal RNA (ssrRNA) gene sequences are available. This project launched a de novo transcriptome assembly with 100 bp paired-end RNA-seq reads from normal, starved and wet-plate cultured animals. Trinity assembly tool generated 104,634 transcript contigs with N50 contig being 2195 bp and average contig length at 1103 bp. Transcriptome BLASTX matching results of five nematodes (C. elegans, Strongyloides stercoralis, Necator americanus, Trichuris trichiura, and Pristionchus pacificus) were consistent with their evolutionary relationships. Sixteen genes were identified to be homologous to key elements of the C. elegans RNA interference system, such as Dicer, Argonaute, RNA-dependent RNA polymerase and double strand RNA transport proteins. In starved samples, we observed up-regulation of cuticle related genes and 3 dauer formation genes. Dauer morphology was captured with enlarged phasmid under light microscopy, and dauer and normal larvae counts in clumps had a Pearson's product-moment correlation of 0.805 with P-value = 0.0088. Our results demonstrate that P. strongyloides could be used for studying nematode-related human or pet parasitic diseases. The sequenced assembled transcriptome reported here may be useful to understand the evolution of parasitism in Nematoda.

Dietary Restriction Extends Lifespan through Metabolic Regulation of Innate Immunity

Chronic inflammation predisposes to aging-associated disease, but it is unknown whether immunity regulation might be important for extending healthy lifespan. Here we show that in C. elegans, dietary restriction (DR) extends lifespan by modulating a conserved innate immunity pathway that is regulated by p38 signaling and the transcription factor ATF-7. Longevity from DR depends upon p38-ATF-7 immunity being intact but downregulated to a basal level. p38-ATF-7 immunity accelerates aging when hyperactive, influences lifespan independently of pathogen exposure, and is activated by nutrients independently of mTORC1, a major DR mediator. Longevity from reduced insulin/IGF-1 signaling (rIIS) also involves p38-ATF-7 downregulation, with signals from DAF-16/FOXO reducing food intake. We conclude that p38-ATF-7 is an immunometabolic pathway that senses bacterial and nutrient signals, that immunity modulation is critical for DR, and that DAF-16/FOXO couples appetite to growth regulation. These conserved mechanisms may influence aging in more complex organisms.

Iron/Heme Metabolism-Targeted Gallium(III) Nanoparticles Are Active against Extracellular and Intracellular Pseudomonas aeruginosa and Acinetobacter baumannii

Iron/heme acquisition systems are critical for microorganisms to acquire iron from the human host, where iron sources are limited due to the nutritional immune system and insolubility of the ferric form of iron. Prior work has shown that a variety of gallium compounds can interfere with bacterial iron acquisition. This study explored the intra- and extracellular antimicrobial activities of gallium protoporphyrin (GaPP), gallium mesoporphyrin (GaMP), and nanoparticles encapsulating GaPP or GaMP against the Gram-negative pathogens Pseudomonas aeruginosa and Acinetobacter baumannii, including clinical isolates. All P. aeruginosa and A. baumannii isolates were susceptible to GaPP and GaMP, with MICs ranging from 0.5 to ∼32 μg/ml in iron-depleted medium. Significant intra- and extracellular growth inhibition was observed against P. aeruginosa cultured in macrophages at a gallium concentration of 3.3 μg/ml (5 μM) of all Ga(III) compounds, including nanoparticles. Nanoparticle formulations showed prolonged activity against both P. aeruginosa and A. baumannii in previously infected macrophages. When the macrophages were loaded with the nanoparticles 3 days prior to infection, there was a 5-fold decrease in growth of P. aeruginosa in the presence of single emulsion F127 copolymer nanoparticles encapsulating GaMP (eFGaMP). In addition, all Ga(III) porphyrins and nanoparticles showed significant intracellular and antibiofilm activity against both pathogens, with the nanoparticles exhibiting intracellular activity for 3 days. Ga nanoparticles also increased the survival rate of Caenorhabditis elegans nematodes infected by P. aeruginosa and A. baumannii Our results demonstrate that Ga nanoparticles have prolonged in vitro and in vivo activities against both P. aeruginosa and A. baumannii, including disruption of their biofilms.

Circular Estimate Method (CEM) - a Simple Method to Estimate Caenorhabditis elegans Culture Densities in Liquid Medium

Background

Nematodes are used in many different fields of science, including environmental and biomedical research. Counting and/or estimating nematode numbers is required during research. Although being one of the most common procedures, this apparently simple task is a time-consuming process, prone to errors and concerns regarding procedure, reliability, and accuracy. When an estimate is necessary, there is a traditional manual counting procedure that in this study it will be called as "drop method" (DM). This popular method that extrapolates an animal count from a small drop of fluid shows a high coefficient of variation. To solve this problem, the present study used the free-living nematode Caenorhabditis elegans to develop a new estimation procedure that was based on a relationship between area and volume of a larger sample.

Results

The new method showed a low coefficient of variation and a close relationship between estimated and real counts of the total number of nematodes in large C. elegans suspensions. Reactive oxygen concentration was measured as an example of method application and to allow comparison between methods.

Conclusion

The proposed method is accurate, facile and reproducible, requiring simple, inexpensive materials that make it an excellent alternative to the DM manual counting procedure. Although the DM is faster, its estimates are not as accurate or as precise as those of the new proposed method.

LED based real-time survival bioassays for nematode research

Nematode bioassays are extensively conducted worldwide, either for screening anthelmintic drugs or for assessing the toxicity of drug candidates. Recently, the US Environmental Protection Agency mandated the use of invertebrate models including nematodes especially Caenorhabditis elegans, for toxicity testing as an alternative to rodent models. The significance of nematode bioassays in the biological sciences is escalating, but no standardized protocol is available to assess nematode mortality in a liquid medium. Manual counting under white light is the only approach currently practiced, which exhibit large variabilities and false positive results. Here, we describe an innovative counting strategy that employs light-emitting diode (LED) technology. We found that the nematodes stopped moving under white light (360–760 nm) when administered with sub-lethal dosage (LC₅₀) of a toxic drug, whereas they responded rapidly to blue (450–490 nm) and ultraviolet (UV) (100–400 nm) LED lights. Furthermore, paralyzed nematodes responded in less than 5 seconds to a LED pulse. The response to the LED stimulus was distinctively noted in C. elegans dauers, which squirmed away from illuminated sites within seconds. LED produced an incoherent beam, and uniformly distributed light across the sampling area. In conclusion, this method is more accurate than the conventional counting techniques, and enables us to differentiate paralyzed and dead nematodes virtually in real-time. Furthermore, this technique would appear to be suitable for incorporating a motion-sensor based automated system.