SKN-1-independent transcriptional activation of glutathione S-transferase 4 (GST-4) by EGF signaling

Tracking Chlamydia - Host interactions and antichlamydial activity in Caenorhabditis elegans

The fading efficacy of antibiotics is a growing global health concern due to its life-threatening consequences and increased healthcare costs. Non-genetic mechanisms of antimicrobial resistance, such as those employed by Chlamydia pneumoniae and Chlamydia trachomatis, complicate treatment as these bacteria can enter a non-replicative, persistent state under stress, evading antibiotics and linking to inflammatory conditions. Understanding chlamydial persistence at the molecular level is challenging, and new models for studying Chlamydia-host interactions in vivo are urgently needed. Caenorhabditis elegans offers an alternative given its immune system and numerous orthologues of human genes. This study established C. elegans as an in vivo model for chlamydial infection. Both Chlamydia species reduced the worm's lifespan, their DNA being detectable at three- and six-days post-infection. Azithromycin at its MIC (25 nM) failed to prevent the infection-induced lifespan reduction, indicating a persister phenotype. In contrast, the methanolic extract of Schisandra chinensis berries showed anti-chlamydial activity both in vitro (in THP-1 macrophages) and in vivo, significantly extending the lifespan of infected C. elegans and reducing the bacterial load. Moreover, S. chinensis increased the transcriptional activity of SKN-1 in the worms, but was unable to impact the bacterial load or lifespan in a sek-1 defective C. elegans strain. In summary, this study validated C. elegans as a chlamydial infection model and showcased S. chinensis berries' in vivo anti-chlamydial potential, possibly through SEK/SKN-1 signaling modulation.

Ovalbumin promotes innate immune response of Caenorhabditis elegans through DAF-16 and SKN-1 pathways in insulin/IGF-1 signaling

Ovalbumin (OVA) is a major allergen in eggs and could induce severe allergic reactions in sensitive individuals, where the innate immune system works as a regulator. The mechanism of how innate immunity adjusts to food allergy is relatively well-studied, however, the effects of allergen uptake on the innate immune system remain unclear. Therefore, the Caenorhabditis elegans (C. elegans) model was utilized to assess the effects of OVA on its innate immune system. OVA enhanced the immune response of C. elegans with higher survival rates under Pseudomonas aeruginosa infection. Moreover, sustaining OVA treatment improved the health states that were reflected in the prolonged lifespan, alleviated oxidative stress, accelerated growth, and promoted motility. RNA-sequencing analysis and the slow-killing assays in the mutants of insulin/IGF-1 signaling (IIS)-related genes confirmed that IIS was necessary for OVA to regulate innate immunity. Besides, OVA activated SKN-1 temporarily and facilitated the nuclear localization of DAF-16 for improving immunity and health status in C. elegans. Together, OVA could enhance the innate immune responses via DAF-16 and SKN-1 pathways in the IIS of C. elegans, and this work will provide novel insights into the regulation of innate immunity by OVA in higher organisms.

Experimental variables that impact outcomes in Caenorhabditis elegans aging stress response

Cellular stress is a fundamental component of age-associated disease. Cells encounter various forms of stress - oxidative stress, protein misfolding, DNA damage, etc. - and respond by activating specific, well-defined stress response pathways. As we age, the burden of stress and resulting damage increases while our cells' ability to deal with the consequences becomes diminished due to dysregulation of cellular stress response pathways. Many interventions that extend lifespan activate one or more stress response pathways or allow cells to maintain normal stress response later in life. The nematode Caenorhabditis elegans is a commonly used model for both aging and stress response research. As such, stress response experiments are regularly conducted as part of studies focused on mechanisms of aging in C. elegans. However, experimental design across experiments in the field are highly variable, including stressor dose, age at exposure, culture type (liquid vs. solid), bacterial strain used as a food source, and environmental temperature. These differences can result in different experimental outcomes, making comparison of results between studies challenging. Here we evaluate several experimental variables that are variable in the published literature and find that each can meaningfully alter experimental outcomes for multiple stressors. Our goal is to raise awareness of the issue of experimental variability within the field and suggest a standardized experimental design to serve as a set of guidelines for future experiments. By adopting these guidelines as a starting point, and explicitly noting differences in specific experiments, we aim to promote rigor and reproducibility, ultimately fostering more interpretable and translatable outcomes in geroscience research.

Probiotic effects of Lactococcus lactis and Leuconostoc mesenteroides on stress and longevity in Caenorhabditis elegans

The short lifespan of Caenorhabditis elegans enables the efficient investigation of probiotic interventions affecting stress and longevity involving the potential therapeutic value of Lactococcus lactis and Leuconostoc mesenteroides isolated from organic basil. The lactic acid bacteria were cultured from the produce collected from a local grocery store in Tulsa, Oklahoma, and then identified through 16S rDNA sequencing and biochemical tests. To dive deep into this analysis for potential probiotic therapy, we used fluorescent reporters that allow us to assess the differential induction of multiple stress pathways such as oxidative stress and the cytoplasmic, endoplasmic reticulum, and the mitochondrial unfolded protein response. This is combined with the classic health span measurements of survival, development, and fecundity, allowing a wide range of organismal observations of the different communities of microbes supported by probiotic supplementation with Lactococcus lactis and Leuconostoc mesenteroides. These strains were initially assessed in relation to the Escherichia coli feeding strain OP50 and the C. elegans microbiome. The supplementation showed a reduction in the median lifespan of the worms colonized within the microbiome. This was unsurprising, as negative results are common when probiotics are introduced into healthy microbiomes. To further assess the supplementation potential of these strains on an unhealthy (undifferentiated) microbiome, the typical axenic C. elegans diet, OP50, was used to simulate this single-species biome. The addition of lactic acid bacteria to OP50 led to a significant improvement in the median and overall survival in simulated biomes, indicating their potential in probiotic therapy. The study analyzed the supplemented cultures in terms of C. elegans' morphology, locomotor behavior, reproduction, and stress responses, revealing unique characteristics and stress response patterns for each group. As the microbiome's influence on the health span gains interest, the study aims to understand the microbiome relationships that result in differential stress resistance and lifespans by supplementing microbiomes with Lactococcus lactis and Leuconostoc mesenteroides isolated from organic basil in C. elegans.

Ribosome biogenesis disruption mediated chromatin structure changes revealed by SRAtac, a customizable end to end analysis pipeline for ATAC-seq

The nucleolus is a large nuclear body that serves as the primary site for ribosome biogenesis. Recent studies have suggested that it also plays an important role in organizing chromatin architecture. However, to establish a causal relationship between nucleolar ribosome assembly and chromatin architecture, genetic tools are required to disrupt nucleolar ribosome biogenesis. In this study, we used ATAC-seq to investigate changes in chromatin accessibility upon specific depletion of two ribosome biogenesis components, RPOA-2 and GRWD-1, in the model organism Caenorhabditis elegans. To facilitate the analysis of ATAC-seq data, we introduced two tools: SRAlign, an extensible NGS data processing workflow, and SRAtac, a customizable end-to-end ATAC-seq analysis pipeline. Our results revealed highly comparable changes in chromatin accessibility following both RPOA-2 and GRWD-1 perturbations. However, we observed a weak correlation between changes in chromatin accessibility and gene expression. While our findings corroborate the idea of a feedback mechanism between ribosomal RNA synthesis, nucleolar ribosome large subunit biogenesis, and chromatin structure during the L1 stage of C. elegans development, they also prompt questions regarding the functional impact of these alterations on gene expression.

2-Butoxytetrahydrofuran and Palmitic Acid from Holothuria scabra Enhance C. elegans Lifespan and Healthspan via DAF-16/FOXO and SKN-1/NRF2 Signaling Pathways

Extracts from a sea cucumber, Holothuria scabra, have been shown to exhibit various pharmacological properties including anti-oxidation, anti-aging, anti-cancer, and anti-neurodegeneration. Furthermore, certain purified compounds from H. scabra displayed neuroprotective effects against Parkinson's and Alzheimer's diseases. Therefore, in the present study, we further examined the anti-aging activity of purified H. scabra compounds in a Caenorhabditis elegans model. Five compounds were isolated from ethyl acetate and butanol fractions of the body wall of H. scabra and characterized as diterpene glycosides (holothuria A and B), palmitic acid, bis (2-ethylhexyl) phthalate (DEHP), and 2-butoxytetrahydrofuran (2-BTHF). Longevity assays revealed that 2-BTHF and palmitic acid could significantly extend lifespan of wild type C. elegans. Moreover, 2-BTHF and palmitic acid were able to enhance resistance to paraquat-induced oxidative stress and thermal stress. By testing the compounds' effects on longevity pathways, it was shown that 2-BTHF and palmitic acid could not extend lifespans of daf-16, age-1, sir-2.1, jnk-1, and skn-1 mutant worms, indicating that these compounds exerted their actions through these genes in extending the lifespan of C. elegans. These compounds induced DAF-16::GFP nuclear translocation and upregulated the expressions of daf-16, hsp-16.2, sod-3 mRNA and SOD-3::GFP. Moreover, they also elevated protein and mRNA expressions of GST-4, which is a downstream target of the SKN-1 transcription factor. Taken together, the study demonstrated the anti-aging activities of 2-BTHF and palmitic acid from H. scabra were mediated via DAF-16/FOXO insulin/IGF and SKN-1/NRF2 signaling pathways.

Neurotoxicity Evaluation of Nanomaterials Using C. elegans: Survival, Locomotion Behaviors, and Oxidative Stress

Nanomaterials are broadly used in a variety of industries and consumer products. However, studies have demonstrated that many nanomaterials, including metal-containing nanoparticles and nanoplastics, have neurotoxic effects. Caenorhabditis elegans (C. elegans) is a widely used model organism with numerous advantages for research, including transparency, short life span, well-characterized nervous system, complete connectome, available genome, and numerous genetic tools. C. elegans has been extensively used to assess the neurotoxicity of multiple chemicals via survival assays, behavioral tests, neuronal morphology studies, and various molecular and mechanistic analyses. However, detailed protocols describing general assays in C. elegans to examine the neurotoxic effects of nanomaterials are limited. Here, we describe protocols for assessing nanomaterial neurotoxicity in C. elegans. We describe the steps for exposure and subsequent evaluation of survival, locomotion behavior, and oxidative stress. Survival and locomotion behavior are measured in wild-type N2 strains to assess acute neurotoxicity. Oxidative stress is used as an endpoint here since it is one of the most predominant and common changes induced by nanomaterials. VP596 nematodes, which express GFP upon activation of skn-1 (the worm homolog of Nrf2), are evaluated for assays of oxidative stress in response to test nanomaterials. These assays can be readily used to quickly examine the neurotoxicity of nanomaterials in vivo, laying the foundation for mechanistic studies of nanomaterials and their impacts on health and physiology. © 2022 Wiley Periodicals LLC. Basic Protocol 1: Exposure of C. elegans to nanomaterials Basic Protocol 2: Survival assessment Basic Protocol 3: Assessment of locomotion behavior Basic Protocol 4: Analysis of oxidative stress.

Aryl Hydrocarbon Receptor-Dependent and -Independent Pathways Mediate Curcumin Anti-Aging Effects

The aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor whose activity can be modulated by polyphenols, such as curcumin. AhR and curcumin have evolutionarily conserved effects on aging. Here, we investigated whether and how the AhR mediates the anti-aging effects of curcumin across species. Using a combination of in vivo, in vitro, and in silico analyses, we demonstrated that curcumin has AhR-dependent or -independent effects in a context-specific manner. We found that in Caenorhabditis elegans, AhR mediates curcumin-induced lifespan extension, most likely through a ligand-independent inhibitory mechanism related to its antioxidant activity. Curcumin also showed AhR-independent anti-aging activities, such as protection against aggregation-prone proteins and oxidative stress in C. elegans and promotion of the migratory capacity of human primary endothelial cells. These AhR-independent effects are largely mediated by the Nrf2/SKN-1 pathway.

Handelin extends lifespan and healthspan of Caenorhabditis elegans by reducing ROS generation and improving motor function

Aging and aging-related disorders contribute to formidable socioeconomic and healthcare challenges. Several promising small molecules have been identified to target conserved genetic pathways delaying aging to extend lifespan and healthspan in many organisms. We previously found that extract from an edible and medicinal plant Chrysanthemum indicum L. (C. indicum L.) protect skin from UVB-induced photoaging, partially by reducing reactive oxygen species (ROS) generation. Thus, we hypothesized that C. indicum L. and its biological active compound may extend lifespan and health span in vivo. We find that both water and ethanol extracts from C. indicum L. extended lifespan of Caenorhabditis elegans, with better biological effect on life extending for ethanol extracts. As one of the major biological active compounds, handelin extended lifespan of C. elegans too. RNA-seq analysis revealed overall gene expression change of C. elegans post stimulation of handelin focus on several antioxidative proteins. Handelin significantly reduced ROS level and maintained the number and morphology of mitochondria. Moreover, handelin improveed many C. elegans behaviors related to healthspan, including increased pharyngeal pumping and body movement. Muscle fiber imaging analyses revealed that handelin maintains muscle architecture by stabilizing myofilaments. In conclusion, our present study finds a novel compound handelin, from C. indicum L., which bring about biologically beneficial effects by mild stress response, termed as hormetin, that can extend both lifespan and healthspan in vivo on C. elegans. Further study on mammal animal model of natural aging or sarcopenia will verify the potential clinical value of handelin.

Protective Effects of Transient Glucose Exposure in Adult C. elegans

C. elegans are used to study molecular pathways, linking high glucose levels (HG) to diabetic complications. Persistent exposure of C. elegans to a HG environment induces the mitochondrial formation of reactive oxygen species (ROS) and advanced glycation endproducts (AGEs), leading to neuronal damage and decreased lifespan. Studies suggest that transient high glucose exposure (TGE) exerts different effects than persistent exposure. Thus, the effects of TGE on ROS, AGE-formation and life span were studied in C. elegans. Four-day TGE (400 mM) as compared to controls (0mM) showed a persistent increase of ROS (4-days 286 ± 40 RLUs vs. control 187 ± 23 RLUs) without increased formation of AGEs. TGE increased body motility (1-day 0.14 ± 0.02; 4-days 0.15 ± 0.01; 6-days 0.16 ± 0.02 vs. control 0.10 ± 0.02 in mm/s), and bending angle (1-day 17.7 ± 1.55; 3-days 18.7 ± 1.39; 6-days 20.3 ± 0.61 vs. control 15.3 ± 1.63 in degree/s) as signs of neuronal damage. Lifespan was increased by 27% (21 ± 2.4 days) after one-day TGE, 34% (22 ± 1.2 days) after four-days TGE, and 26% (21 ± 1.4 days) after six-days TGE vs. control (16 ± 1.3 days). These experiments suggest that TGE in C. elegans has positive effects on life span and neuronal function, associated with mildly increased ROS-formation. From the perspective of metabolic memory, hormetic effects outweighed the detrimental effects of a HG environment.

p21-Activated kinase 1 (PAK1) in aging and longevity: An overview

The p21-activated kinases (PAKs) belong to serine/threonine kinases family, regulated by ∼21 kDa small signaling G proteins RAC1 and CDC42. The mammalian PAK family comprises six members (PAK1-6) that are classified into two groups (I and II) based on their domain architecture and regulatory mechanisms. PAKs are implicated in a wide range of cellular functions. PAK1 has recently attracted increasing attention owing to its involvement in oncogenesis, tumor progression, and metastasis as well as several life-limiting diseases and pathological conditions. In Caenorhabditis elegans, PAK1 functions limit the lifespan under basal conditions by inhibiting forkhead transcription factor DAF-16. Interestingly, PAK depletion extended longevity and attenuated the onset of age-related phenotypes in a premature-aging mouse model and delayed senescence in mammalian fibroblasts. These observations implicate PAKs as not only oncogenic but also aging kinases. Therefore, PAK-targeting genetic and/or pharmacological interventions, particularly PAK1-targeting, could be a viable strategy for developing cancer therapies with relatively no side effects and promoting healthy longevity. This review describes PAK family proteins, their biological functions, and their role in regulating aging and longevity using C. elegans. Moreover, we discuss the effect of small-molecule PAK1 inhibitors on the lifespan and healthspan of C. elegans.

Ferulic Acid Supplementation Increases Lifespan and Stress Resistance via Insulin/IGF-1 Signaling Pathway in C. elegans

Ferulic acid (FA) is a naturally-occurring well-known potent antioxidant and free radical scavenger. FA supplementation is an effective strategy to delay aging, but the underlying mechanism remains unknown. In the present study, we examined the effects of FA on lifespan extension and its mechanism of FA in Caenorhabditis elegans (C. elegans). Results suggested that FA increased the lifespan of C. elegans, rather than altering the growth of E. coli OP50. Meanwhile, FA promoted the healthspan of C. elegans by improving locomotion and reducing fat accumulation and polyQ aggregation. FA increased the resistance to heat and oxidative stress through reducing ROS. The upregulating of the expression of the hlh-30, skn-1, and hsf-1 were involved in the FA-mediated lifespan extension. Furthermore, FA treatment had no impact on the lifespan of daf-2, hlh-30, skn-1, and hsf-1 mutants, confirming that insulin/IGF-1 signaling pathway and multiple longevity mechanisms were associated with the longevity mechanism of FA. We further found that mitochondrial signaling pathway was modulation involved in FA-mediated lifespan extension. With the results from RNA-seq results and mutants lifespan assay. These findings contribute to our knowledge of the lifespan extension and underlying mechanism of action of FA in C. elegans.

Bacterial processing of glucose modulates C. elegans lifespan and healthspan

Intestinal microbiota play an essential role in the health of a host organism. Here, we define how commensal Escherichia coli (E. coli) alters its host after long term exposure to glucose using a Caenorhabditis elegans-E. coli system where only the bacteria have direct contact with glucose. Our data reveal that bacterial processing of glucose results in reduced lifespan and healthspan including reduced locomotion, oxidative stress resistance, and heat stress resistance in C. elegans. With chronic exposure to glucose, E. coli exhibits growth defects and increased advanced glycation end products. These negative effects are abrogated when the E. coli is not able to process the additional glucose and by the addition of the anti-glycation compound carnosine. Physiological changes of the host C. elegans are accompanied by dysregulation of detoxifying genes including glyoxalase, glutathione-S-transferase, and superoxide dismutase. Loss of the glutathione-S-transferase, gst-4 shortens C. elegans lifespan and blunts the animal's response to a glucose fed bacterial diet. Taken together, we reveal that added dietary sugar may alter intestinal microbial E. coli to decrease lifespan and healthspan of the host and define a critical role of detoxification genes in maintaining health during a chronic high-sugar diet.

Flavonoids' Effects on Caenorhabditis elegans' Longevity, Fat Accumulation, Stress Resistance and Gene Modulation Involve mTOR, SKN-1 and DAF-16

Flavonoids are potential nutraceutical compounds present in diary food. They are considered health-promoting compounds and promising drugs for different diseases, such as neurological and inflammatory diseases, diabetes and cancer. Therefore, toxicological and mechanistic studies should be done to assert the biological effects and identify the molecular targets of these compounds. In this work we describe the effects of six structurally-related flavonoids—baicalein, chrysin, scutellarein, 6-hydroxyflavone, 6,7-dihydroxyflavone and 7,8-dihydroxyflavone—on Caenorhabditis elegans’ lifespan and stress resistance. The results showed that chrysin, 6-hydroxyflavone and baicalein prolonged C. elegans’ lifespan by up to 8.5%, 11.8% and 18.6%, respectively. The lifespan extensions caused by these flavonoids are dependent on different signaling pathways. The results suggested that chrysin’s effects are dependent on the insulin signaling pathway via DAF-16/FOXO. Baicalein and 6-hydroxyflavone’s effects are dependent on the SKN-1/Nfr2 pathway. In addition, microarray analysis showed that baicalein downregulates important age-related genes, such as mTOR and PARP.

α- and β-Santalols Delay Aging in Caenorhabditis elegans via Preventing Oxidative Stress and Protein Aggregation

α- and β-Santalol (santalol isomers) are the most abundant sesquiterpenoids found in sandalwood, contributing to its pleasant fragrance and wide-spectrum bioactivity. This study aimed at identifying the antiaging and antiaggregation mechanism of α- and β-santalol using the genetic tractability of an in vivo model Caenorhabditis elegans. The results showed that santalol isomers retard aging, improved health span, and inhibited the aggregation of toxic amyloid-β (Aβ1-42) and polyglutamine repeats (Q35, Q40, and HtnQ150) in C. elegans models for Alzheimer's and Huntington's disease, respectively. The genetic study, reporter gene expression, RNA-based reverse genetic approach (RNA interferences/RNAi), and gene expression analysis revealed that santalol isomers selectively regulate SKN-1/Nrf2 and EOR-1/PLZF transcription factors through the RTK/Ras/MAPK-dependent signaling axis that could trigger the expression of several antioxidants and protein aggregation inhibitory genes, viz., gst-4, gcs-1, gst-10, gsr-1, hsp-4, and skr-5, which extend longevity and help minimize age-induced protein oxidation and aggregation. We believe that these findings will further promote α- and β-santalol to become next-generation prolongevity and antiaggregation molecules for longer and healthier life.

Stress and timing associated with Caenorhabditis elegans immobilization methods

Background

Caenorhabditis elegans is a model organism used to study gene, protein, and cell influence on function and behavior. These studies frequently require C. elegans to be immobilized for imaging or laser ablation experiments. There are a number of known techniques for immobilizing worms, but to our knowledge, there are no comprehensive studies of the various agents in common use today.

New method

This study determines the relationship between concentration, immobilization time, exposure time, and recovery likelihood for several immobilization agents. The agents used in this study are 1-Phenoxy-2-propanol, levamisole, sodium azide, polystyrene beads, and environmental cold shock. These tests are conducted using a humidified chamber to keep chemical concentrations consistent. Each of these agents is also tested to determine if they exhibit stress-related after effects using the gcs-1, daf-16, hsp-4, hif-1, hsp-16.2, and tmem-135 stress reporters.

Results

We present a range of quick mount immobilization and recovery conditions for each agent tested. This study shows that, under controlled conditions, 1-Phenoxy-2-propanol shows significant stress from the daf-16 reporter. While 1-Phenoxy-2-propanol and sodium azide both create stress related after effects with long term recovery in the case of the hsp-16.2 reporter.

Comparison with existing method(s)

This study shows that commonly used concentrations of immobilizing agents are ineffective when evaporation is prevented.

Conclusions

To improve reproducibility of results it is essential to use consistent concentrations of immobilizing agents. It is also critically important to account for stress-related after effects elicited by immobilization agents when designing any experiment.

Thallium Toxicity in Caenorhabditis elegans: Involvement of the SKN-1 Pathway and Protection by S-Allylcysteine

Monovalent thallium (Tl⁺) is a cation that can exert complex neurotoxic patterns in the brain by mechanisms that have yet to be completely characterized. To learn more about Tl⁺ toxicity, it is necessary to investigate its major effects in vivo and its ability to trigger specific signaling pathways (such as the antioxidant SKN-1 pathway) in different biological models. Caenorhabditis elegans (C. elegans) is a nematode constituting a simple in vivo biological model with a well-characterized nervous system, and high genetic homology to mammalian systems. In this study, both wild-type (N2) and skn-1 knockout (KO) mutant C. elegans strains subjected to acute and chronic exposures to Tl⁺ [2.5-35 μM] were evaluated for physiological stress (survival, longevity, and worm size), motor alterations (body bends), and biochemical changes (glutathione S-transferase regulation in a gst-4 fluorescence strain). While survival was affected by Tl⁺ in N2 and skn-1 KO (worms lacking the orthologue of mammalian Nrf2) strains in a similar manner, the longevity was more prominently decreased in the skn-1 KO strain compared with the wild-type strain. Moreover, chronic exposure led to a greater compromise in the longevity in both strains compared with acute exposure. Tl⁺ also induced motor alterations in both skn-1 KO and wild-type strains, as well as changes in worm size in wild-type worms. In addition, preconditioning nematodes with the well-known antioxidant S-allylcysteine (SAC) reversed the Tl⁺-induced decrease in survival in the N2 strain. GST fluorescent expression was also decreased by the metal in the nematode, and recovered by SAC. Our results describe and validate, for the first time, features of the toxic pattern induced by Tl⁺ in an in vivo biological model established with C. elegans, supporting an altered redox component in Tl⁺ toxicity, as previously described in mammal models. We demonstrate that the presence of the orthologous SKN-1 pathway is required for worms in evoking an efficient antioxidant defense. Therefore, the nematode represents an optimal model to reproduce mammalian Tl⁺ toxicity, where toxic mechanisms and novel therapeutic approaches of clinical value may be successfully pursued.

Disruption of mitochondrial dynamics increases stress resistance through activation of multiple stress response pathways

Mitochondria are dynamic organelles that can change shape and size depending on the needs of the cell through the processes of mitochondrial fission and fusion. In this work, we investigated the role of mitochondrial dynamics in organismal stress response. By using C. elegans as a genetic model, we could visualize mitochondrial morphology in a live organism with well‐established stress assays and well‐characterized stress response pathways. We found that disrupting mitochondrial fission (DRP1/drp‐1) or fusion (OPA1/eat‐3, MFN/fzo‐1) genes caused alterations in mitochondrial morphology that impacted both mitochondrial function and physiologic rates. While both mitochondrial fission and mitochondrial fusion mutants showed increased sensitivity to osmotic stress and anoxia, surprisingly we found that the mitochondrial fusion mutants eat‐3 and fzo‐1 are more resistant to both heat stress and oxidative stress. In exploring the mechanism of increased stress resistance, we found that disruption of mitochondrial fusion genes resulted in the upregulation of multiple stress response pathways. Overall, this work demonstrates that disrupting mitochondrial dynamics can have opposite effects on resistance to different types of stress. Our results suggest that disruption of mitochondrial fusion activates multiple stress response pathways that enhance resistance to specific stresses.

Antioxidant CoQ10 Restores Fertility by Rescuing Bisphenol A-Induced Oxidative DNA Damage in the Caenorhabditis elegans Germline

Endocrine-disrupting chemicals are ubiquitously present in our environment, but the mechanisms by which they adversely affect human reproductive health and strategies to circumvent their effects remain largely unknown. Here, we show in Caenorhabditis elegans that supplementation with the antioxidant Coenzyme Q10 (CoQ10) rescues the reprotoxicity induced by the widely used plasticizer and endocrine disruptor bisphenol A (BPA), in part by neutralizing DNA damage resulting from oxidative stress. CoQ10 significantly reduces BPA-induced elevated levels of germ cell apoptosis, phosphorylated checkpoint kinase 1 (CHK-1), double-strand breaks (DSBs), and chromosome defects in diakinesis oocytes. BPA-induced oxidative stress, mitochondrial dysfunction, and increased gene expression of antioxidant enzymes in the germline are counteracted by CoQ10. Finally, CoQ10 treatment also reduced the levels of aneuploid embryos and BPA-induced defects observed in early embryonic divisions. We propose that CoQ10 may counteract BPA-induced reprotoxicity through the scavenging of reactive oxygen species and free radicals, and that this natural antioxidant could constitute a low-risk and low-cost strategy to attenuate the impact on fertility by BPA.

CEH-60/PBX regulates vitellogenesis and cuticle permeability through intestinal interaction with UNC-62/MEIS in Caenorhabditis elegans

The onset of sexual maturity involves dramatic changes in physiology and gene expression in many animals. These include abundant yolk protein production in egg-laying species, an energetically costly process under extensive transcriptional control. Here, we used the model organism Caenorhabditis elegans to provide evidence for the spatiotemporally defined interaction of two evolutionarily conserved transcription factors, CEH-60/PBX and UNC-62/MEIS, acting as a gateway to yolk protein production. Via proteomics, bimolecular fluorescence complementation (BiFC), and biochemical and functional readouts, we show that this interaction occurs in the intestine of animals at the onset of sexual maturity and suffices to support the reproductive program. Our electron micrographs and functional assays provide evidence that intestinal PBX/MEIS cooperation drives another process that depends on lipid mobilization: the formation of an impermeable epicuticle. Without this lipid-rich protective layer, mutant animals are hypersensitive to exogenous oxidative stress and are poor partners for mating. Dedicated communication between the hypodermis and intestine in C. elegans likely supports these physiological outcomes, and we propose a fundamental role for the conserved PBX/MEIS interaction in multicellular signaling networks that rely on lipid homeostasis.

Lifespan Extending and Oxidative Stress Resistance Properties of a Leaf Extracts from Anacardium occidentale L. in Caenorhabditis elegans

Anacardium occidentale (AO) contains a number of polyphenolic secondary metabolites with antioxidant activity. The objectives of this study were aimed at investigating the roles of AO leaf extracts in antioxidative stress and longevity, as well as their underlying mechanisms, in the Caenorhabditis elegans (C. elegans) model. AO extracts mediated the survival rate of nematodes under oxidative stress by attenuating intracellular reactive oxygen species (ROS) via the DAF-16/FoxO and SKN-1/Nrf-2 signaling pathways. AO extracts stimulated the expression of stress response genes including SOD-3 and GST-4. Moreover, AO extracts exhibited antiaging activities and enhanced longevity. We observed improved pharyngeal pumping function, attenuation of pigment accumulation (lipofuscin), and an increased lifespan of the worms. Collectively, our results demonstrated that AO extracts exerted both oxidative stress resistance and antiaging properties in the C. elegans model and may lead to new agents to benefit humans in the near future.

The glutathione system and the related thiol network in Caenorhabditis elegans

Advances in the field of redox biology have contributed to the understanding of the complexity of the thiol-based system in mediating signal transduction. The redox environment is the overall spatiotemporal balance of oxidation-reduction systems within the integrated compartments of the cell, tissues and whole organisms. The ratio of the reduced to disulfide glutathione redox couple (GSH:GSSG) is a key indicator of the redox environment and its associated cellular health. The reaction mechanisms of glutathione-dependent and related thiol-based enzymes play a fundamental role in the function of GSH as a redox regulator. Glutathione homeostasis is maintained by the balance of GSH synthesis (de novo and salvage pathways) and its utilization through its detoxification, thiol signalling, and antioxidant defence functions via GSH-dependent enzymes and free radical scavenging. As such, GSH acts in concert with the entire redox network to maintain reducing conditions in the cell. Caenorhabditis elegans offers a simple model to facilitate further understanding at the multicellular level of the physiological functions of GSH and the GSH-dependent redox network. This review discusses the C. elegans studies that have investigated glutathione and related systems of the redox network including; orthologs to the protein-encoding genes of GSH synthesis; glutathione peroxidases; glutathione-S-transferases; and the glutaredoxin, thioredoxin and peroxiredoxin systems.

Chronic exposure to a glyphosate-containing pesticide leads to mitochondrial dysfunction and increased reactive oxygen species production in Caenorhabditis elegans

Glyphosate-containing herbicides are among the most widely-used in the world. Although glyphosate itself is relatively non-toxic, growing evidence suggests that commercial herbicide formulations may lead to increased oxidative stress and mitochondrial inhibition. In order to assess these mechanisms in vivo, we chronically (24h) exposed Caenorhabditis elegans to various concentrations of the glyphosate-containing herbicide TouchDown (TD). Following TD exposure, we evaluated the function of specific mitochondrial electron transport chain complexes. Initial oxygen consumption studies demonstrated inhibition in mid- and high-TD concentration treatment groups compared to controls. Results from tetramethylrhodamine ethyl ester and ATP assays indicated reductions in the proton gradient and ATP levels, respectively. Additional studies were designed to determine whether TD exposure resulted in increased reactive oxygen species (ROS) production. Data from hydrogen peroxide, but not superoxide or hydroxyl radical, assays showed statistically significant increases in this specific ROS. Taken together, these data indicate that exposure of Caenorhabditis elegans to TD leads to mitochondrial inhibition and hydrogen peroxide production.