Trans-generational effects of copper on nerve damage in Caenorhabditis elegans

Mitochondria UPR stimulation by pelargonidin-3-glucoside contributes to ameliorating lipid accumulation under copper exposure

Intensification of copper pollution in the environment has led to its excessive accumulation in humans, causing oxidative stress and lipid metabolism disorders. It is necessary to look for effective targets and safe methods to alleviate copper toxicity. Pelargonidin-3-glucoside (Pg3G) is a natural anthocyanin with metal ion chelating ability and multiple physiological activities. In this study, lipid accumulation was investigated under copper exposure in Caenorhabditis elegans which can be improved by Pg3G. Transcriptome analysis revealed that differentially expressed genes are enriched in lipid metabolism and protein folding/degradation. Pg3G activated mitochondrial unfold protein response (UPRmt) to mitigate mitochondrial damage caused by copper and regulated the expression of genes involved in lipid absorption, transport, and synthesis, thereby reducing lipid levels in C. elegans. This improvement disappeared in the ubl-5 knockout strain, indicating that ubl-5 is one target of Pg3G. Meanwhile, in HepG2 cells, Pg3G enhanced the cellular antioxidant capacity by activating UPRmt for maintaining mitochondrial homeostasis, followed by inhibition of excessive lipid accumulation. Overall, these results suggested that UPRmt activation can be a strategy for mitigating lipid disorders induced by copper and Pg3G with excellent ability to resist oxidative stress specially targeted for ubl-5 has a promising application in controlling copper contamination.

Nanoplastics aggravated TDCIPP-induced transgenerational developmental neurotoxicity in zebrafish depending on the involvement of the dopamine signaling pathway

Plastics pose a hazard to the environment. Although plastics have toxicity, microplastics (MPs) and nanoplastics (NPs) are capable of interacting with the rest pollutants in the environment, so they serve as the carriers and interact with organic pollutants to modulate their toxicity, thus resulting in unpredictable ecological risks. PS-NPs and TDCIPP were used expose from 2 h post-fertilization (hpf) to 150 days post-fertilization (dpf) to determine the bioaccumulation of tris(1,3-dichloro-2-propyl) phosphate (TDCIPP) and its potential effects on neurodevelopment in F1 zebrafish (Danio rerio) offspring under the action of polystyrene nano plastics (PS-NPs). The exposure groups were assigned to TDCIPP (0, 0.4, 2 or 10 µg/L) alone group and the PS-NPs (100 µg/L) and TDCIPP co-exposed group. F1 embryos were collected and grown in clean water to 5 dpf post-fertilization. PS-NPs facilitated the bioaccumulation of TDCIPP in the gut, gill, head，gonad and liver of zebrafish in a sex-dependent manner and promoted the transfer of TDCIPP to their offspring, thus contributing to PS-NPs aggravated the inhibition of offspring development and neurobehavior of TDCIPP-induced. In comparison with TDCIPP exposure alone, the combination could notably down-regulate the levels of the dopamine neurotransmitter, whereas the levels of serotonin or acetylcholine were not notably different. This result was achieved probably because PS-NPs interfered with the TDCIPP neurotoxic response of zebrafish F1 offspring not through the serotonin or acetylcholine neurotransmitter pathway. The increased transfer of TDCIPP to the offspring under the action of PS-NPs increased TDCIPP-induced transgenerational developmental neurotoxicity, which was proven by a further up-regulation/down-regulation the key gene and protein expression related to dopamine synthesis, transport, and metabolism in F1 larvae, in contrast to TDCIPP exposure alone. The above findings suggested that dopaminergic signaling involvement could be conducive to the transgenerational neurodevelopmental toxicity of F1 larval upon parental early co-exposure to PS-NPs and TDCIPP.

Copper Homeostasis in the Model Organism C. elegans

Cellular and organismic copper (Cu) homeostasis is regulated by Cu transporters and Cu chaperones to ensure the controlled uptake, distribution and export of Cu ions. Many of these processes have been extensively investigated in mammalian cell culture, as well as in humans and in mammalian model organisms. Most of the human genes encoding proteins involved in Cu homeostasis have orthologs in the model organism, Caenorhabditis elegans (C. elegans). Starting with a compilation of human Cu proteins and their orthologs, this review presents an overview of Cu homeostasis in C. elegans, comparing it to the human system, thereby establishing the basis for an assessment of the suitability of C. elegans as a model to answer mechanistic questions relating to human Cu homeostasis.

FoxO signaling pathway stimulation by Bacillus smithii XY1 contributes to alleviating copper-induced neurotoxicity

Increasingly copper pollution in the environment exacerbates the risk of neurodegenerative diseases. It is necessary to look for effective targets and safe methods for protecting from copper-induced neurotoxicity. Here we firstly explored the impact of copper-exposure on expression profiles in zebrafish. Copper reduced embryo hatching, increased mortality and caused embryonic developmental abnormalities and behavioral dysfunction in juveniles. Transcriptomic analysis revealed that differential genes related to neuron were highly associated with oxidative stress especially enriched to FoxO pathway. Through further validation in Caenorhabditis elegans, copper resulted in nematode neurodegenerative movement disorders and neuronal damage, along with increased levels of reactive oxygen species (ROS) as well as decreased expressions of antioxidant-related enzymes and downstream genes which was also involved in FoxO signaling pathway. Bacillus smithii XY1, a novel strain with an excellent antioxidative activity, showed a great alleviative effect on copper-induced neurotoxicity that was related to FoxO stimulation, being a potential candidate for copper pollution management. Overall, these results suggested that FoxO pathway activation can regard as a strategy for mitigating neurotoxicity caused by copper and B. smithii XY1 with excellent tolerance and outstanding antioxidation specially targeted for FoxO has a promising application in controlling copper contamination.

Dysfunction in atox-1 and ceruloplasmin alters labile Cu levels and consequently Cu homeostasis in C. elegans

Copper (Cu) is an essential trace element, however an excess is toxic due to its redox properties. Cu homeostasis therefore needs to be tightly regulated via cellular transporters, storage proteins and exporters. An imbalance in Cu homeostasis has been associated with neurodegenerative disorders such as Wilson's disease, but also Alzheimer's or Parkinson's disease. In our current study, we explored the utility of using Caenorhabditis elegans (C. elegans) as a model of Cu dyshomeostasis. The application of excess Cu dosing and the use of mutants lacking the intracellular Cu chaperone atox-1 and major Cu storage protein ceruloplasmin facilitated the assessment of Cu status, functional markers including total Cu levels, labile Cu levels, Cu distribution and the gene expression of homeostasis-related genes. Our data revealed a decrease in total Cu uptake but an increase in labile Cu levels due to genetic dysfunction, as well as altered gene expression levels of Cu homeostasis-associated genes. In addition, the data uncovered the role ceruloplasmin and atox-1 play in the worm's Cu homeostasis. This study provides insights into suitable functional Cu markers and Cu homeostasis in C. elegans, with a focus on labile Cu levels, a promising marker of Cu dysregulation during disease progression.

Evaluation of a battery of biotests to improve waste ecotoxicity assessment (HP 14), using incineration bottom ash as a case study

The assessment of waste ecotoxicity (hazardous property HP14 in the European Union) is fundamental for proper waste classification and safe application/disposal. Biotests are relevant for evaluating waste complex matrices, but their efficiency is crucial to encourage their adoption at the industrial level. This work aims at evaluating possibilities of improving the efficiency of a biotest battery previously suggested in the literature, regarding test selection, duration, and/or laboratory resources optimization. Fresh incineration bottom ash (IBA) was the case study. The test battery analysed included standard aquatic (bacteria, microalgae, macrophytes, daphnids, rotifers, fairy shrimp) and terrestrial (bacteria, plants, earthworms, collembolans) organisms. The assessment followed an Extended Limit Test design (three dilutions of eluate or solid IBA) and the Lowest Ineffective Dilution (LID-approach) for ecotoxicity classification. The results emphasize the importance of testing different species. It was also evidenced that tests with daphnids and earthworms may be shortened to 24 h; the miniaturization of tests is suitable as e.g. differential sensitivity of microalgae and macrophytes was captured with low variability; alternative testing kits can be used when methodological difficulties are found. Microalgae were more sensitive than macrophytes. Similar results were found for the Thamnotoxkit and daphnids test for eluates with natural pH, so the former may be used as an alternative. B. rapa was the most sensitive organism, suggesting that it may be tested as the only terrestrial plant species and that minimum test duration is appropriate. F. candida does not appear to add information to the battery. The differences in sensitivity of A. fischeri and E. fetida compared to the remaining species were not significant enough to exclude them from the battery. Thus, this work suggests a biotest battery to test IBA comprising aquatic tests - Aliivibrio fischeri, Raphidocelis subcapitata (miniaturised test), and Daphnia magna (24 h when clear deleterious effects are observed) or Thamnocephalus platyurus (toxkit) - and terrestrial tests - Arthrobacter globiformis, Brassica rapa (14 d), and Eisenia fetida (24 h). Testing waste with natural pH is also recommended. The Extended Limit Test design considering the LID-approach seems useful in waste testing, particularly for the industry, involving low effort, test material requirements, and few laboratory resources. The LID-approach allowed for differentiating ecotoxic from non-ecotoxic effects and captured different sensitivities between species. Ecotoxicological assessment of other waste may benefit from these recommendations, but caution should be taken given the properties of each waste type.

Multigenerational effects of co-exposure to dimethylarsinic acid and polystyrene microplastics on the nematode Caenorhabditis elegans

In the current study, we assessed the impact of DMA (dimethylarsinic acid) and MPs (microplastics) interactions in C. elegans over the course of five generations. We found that the redox state of the organisms changed over generations as a result of exposure to both pollutants. From the third generation onward, exposure to MPs reduced GST activity, indicating reduced detoxifying abilities of these organisms. Additionally, dimethylarsinic exposure decreased the growth of organisms in the second, fourth, and fifth generations. In comparison to isolated pollutants, the cumulative effects of co-exposure to DMA and MPs seem to have been more harmful to the organisms, as demonstrated by correlation analysis. These findings demonstrate that DMA, despite being considered less hazardous than its inorganic equivalents, can still have toxic effects on species at low concentrations and the presence of MPs, can worsen these effects.

Upregulation of postsynaptic cAMP/PKA/CREB signaling alleviates copper(Ⅱ)-induced oxidative stress and pyroptosis in MN9D cells

It has been widely reported that long-term exposure to copper increases the prevalence and mortality of Parkinson's disease. Our previous study showed that CuSO₄ exposure induced a significant increase in the expression of cleaved Caspase1 proteins and the loss of dopaminergic neurons in the SNpc of mice. In this study, the effects of copper(Ⅱ) on cAMP/PKA/CREB pathway and pyroptosis-related proteins in MN9D cells were investigated by setting up copper(Ⅱ) exposure groups with different concentration gradients, to provide possible molecular evidence for studying the mechanism of copper(Ⅱ)-induced degeneration of dopaminergic neurons. We found that after 48hours of copper(Ⅱ) exposure, the cu content in MN9D cells increased in a dose-dependent manner, and the proliferation activity decreased significantly. In addition, copper(Ⅱ) exposure caused up-regulation of PDE4D and down-regulation of D1R, cAMP, PKA and p-CREB/CREB. Simultaneously, we proved that copper(Ⅱ) exposure induced oxidative stress in MN9D cells, including decreased GSH-Px content, Keap1 expression and mitochondrial membrane potential, increased malondialdehyde content, ROS intensity, and Nrf2, NQO1, HO-1, HSP-70 expression, further causing up-regulation of inflammasome and GSDMD protein. After pretreatment with Roflupram, the level of copper(Ⅱ)-induced oxidative damage decreased, the expression of inflammasome and GSDMD proteins were down-regulated. However, the protective effects of ROF were blocked by H-89. In summary, copper(Ⅱ) treatment induced oxidative stress and inflammasome-mediated pyroptosis in MN9D cells, which may be related to copper(Ⅱ)-induced postsynaptic cAMP, PKA, and CREB signal transduction disorders.

Bacillus coagulans (Weizmannia coagulans) XY2 attenuates Cu-induced oxidative stress via DAF-16/FoxO and SKN-1/Nrf2 pathways and gut microbiota regulation

Copper (Cu) pollution has become a serious environmental problem especially in recent decades. In this study, the mechanisms of Bacillus coagulans (Weizmannia coagulans) XY2 against Cu-induced oxidative stress were explored through a dual model. In mice, Cu disturbed microbial community structure, revealing an increased level of Enterorhabdus abundance and decreased levels of Intestinimonas, Faecalibaculu, Ruminococcaceae and Coriobacteriaceae_UCG-002 abundance. Meanwhile, B. coagulans (W. coagulans) XY2 intervention reversed this trend along with alleviated Cu-induced metabolic disturbances by increasing levels of hypotaurine and L-glutamate and declining levels of phosphatidylcholine and phosphatidylethanolamine. In Caenorhabditis elegans, nuclear translocation of DAF-16 and SKN-1 was inhibited by Cu, which in turn suppressed antioxidant-related enzymes activities. XY2 mitigated biotoxicity associated with oxidative damage caused by Cu exposure via regulating DAF-16/FoxO and SKN-1/Nrf2 pathways and intestinal flora to eliminate excess ROS. Our study provides a theoretical basis formulating future strategy of probiotics against heavy metal contamination.

Physicochemical properties and biological activities of Tremella hydrocolloids

In this paper, the physicochemical properties, antioxidant and anti-aging abilities of three new Tremella hydrocolloids were studied. The physicochemical properties were characterized by Fourier transform infrared spectroscopy, differential scanning calorimeter, X-ray diffractometry etc. The antioxidant activities of Tremella hydrocolloids were determined by ABTS radical, DPPH radical scavenging activity. The anti-aging ability of Tremella hydrocolloids was also investigated by using the organism model of Caenorhabditis elegans (C. elegans). The results showed that the ES-THD displayed the highest radical scavenging capacity and the best anti-aging abilities. The ability of ES-THD to scavenge ABTS radicals reached 100 % at 2 mg/mL, the ability of ES-THD to scavenge DPPH radicals reached 45.55 %. Compared with the control group, the average lifespan was 29.17 % longer fed with ES-THD. These results provide the evidence basis for the use of Tremella hydrocolloids as food texture modifiers, antioxidants, and anti-aging agents in the food industries.

Automated recognition and analysis of body bending behavior in C. elegans

BACKGROUND

Locomotion behaviors of Caenorhabditis elegans play an important role in drug activity screening, anti-aging research, and toxicological assessment. Previous studies have provided important insights into drug activity screening, anti-aging, and toxicological research by manually counting the number of body bends. However, manual counting is often low-throughput and takes a lot of time and manpower. And it is easy to cause artificial bias and error in counting results.

RESULTS

In this paper, an algorithm is proposed for automatic counting and analysis of the body bending behavior of nematodes. First of all, the numerical coordinate regression method with convolutional neural network is used to obtain the head and tail coordinates. Next, curvature-based feature point extraction algorithm is used to calculate the feature points of the nematode centerline. Then the maximum distance between the peak point and the straight line between the pharynx and the tail is calculated. The number of body bends is counted according to the change in the maximum distance per frame.

CONCLUSION

Experiments are performed to prove the effectiveness of the proposed algorithm. The accuracy of head coordinate prediction is 0.993, and the accuracy of tail coordinate prediction is 0.990. The Pearson correlation coefficient between the results of the automatic count and manual count of the number of body bends is 0.998 and the mean absolute error is 1.931. Different strains of nematodes are selected to analyze differences in body bending behavior, demonstrating a relationship between nematode vitality and lifespan. The code is freely available at https://github.com/hthana/Body-Bend-Count .

Zinc homeostasis may reverse the synergistic neurotoxicity of heavy metal mixtures in Caenorhabditis elegans

Heavy metal mixtures can cause nerve damage. However, the combined effects of metal mixtures are extremely complex and rarely studied. Zinc (Zn) homeostasis plays an integral role in neural function, but the role of Zn homeostasis in the toxicity of metal mixtures is not well understood. Here, we investigated the combined effects of manganese (Mn), lead (Pb) and arsenic (As) on nerves and the effect of Zn homeostasis on metal toxicity. Caenorhabditis elegans (Maupas, 1900) were exposed to single and multiple metals for 8 days, their movement, behavior, neurons and metal concentration were detected to evaluate the combined effect of metal mixtures. After nematodes were co-treated with metal mixtures and Zn, the nerve function, Zn concentration and redox balance were detected to evaluate the effect of Zn homeostasis on metal toxicity. The results showed that Mn + Pb and Pb + As mixtures induced synergistic toxicity for nematode nerves, which damaged movement, behavior and neurons, and decreased Zn concentration. While Zn supplementation recovered Zn homeostasis and promoted redox balance on nematodes, and then improved the nerve function. Our study demonstrated the combined effects of metal mixtures and the neuroprotective effect of Zn homeostasis. Therefore, assessment of metal mixtures toxicity should consider their interaction and the impacts of essential metals homeostasis.

Chronic and transgenerational effects of silver nanoparticles in freshwater gastropod Lymnaea stagnalis

Traditional ecotoxicological studies prove to be focused mainly on single-generation, multigenerational research in ecotoxicological testing is needed to improve the predictive approaches in ecological risk assessment. Silver nanoparticles (AgNPs) have been increasingly detected in aquatic environments due to their extensive use in consumer products. We investigated the transgenerational effects of AgNPs on the life traits of freshwater model gastropods Lymnaea stagnalis for two generations. The reversibility of the effects of using recovery experiments was also performed. Results showed that AgNPs induced high Ag bioaccumulation in the whole soft tissues of parental L. stagnalis after 21 days of exposure. The increased ROS production and reduced condition index and fecundity were found after exposure to AgNPs at 500 μg/L. These results highlight that under AgNPs exposure, adult gastropods might allocate more resources to resist oxidative stress rather than to growth or reproduction. Furthermore, the Ag accumulation and ROS production of egg clutches were significantly related to parental exposure duration and concentrations. On the other hand, isolated eggs exposure demonstrated biological effects were persistent in terms of the next generation. For example, after transfer to a clean medium, similar Ag bioaccumulation and ROS production were observed from eggs which parents were pre-exposed to 50 and 500 μg/L AgNPs. Current explicit consideration of offspring performance adds value to existing toxicity testing protocols. Parental exposure duration has important implications for offspring effects, and parental exposure can cause transgenerational changes in resistance that have significant implications for toxicity testing and adaptive responses. These effects across generations point out the need for multigenerational tests to assess the environmental risk of MNPs in aquatic organisms.

Automated recognition and analysis of head thrashes behavior in C. elegans

Background

Locomotive behaviors are a rapid evaluation indicator reflecting whether the nervous system of worms is damaged, and has been proved to be sensitive to chemical toxicity. In many toxicological studies, C. elegans head thrashes is a key indicator of locomotive behaviors to measure the vitality of worms. In previous studies, the number of head thrashes was manually counted, which is time-consuming and labor-intensive.

Results

This paper presents an automatic recognition and counting method for head thrashes behavior of worms from experimental videos. First, the image processing algorithm is designed for worm morphology features calculation, mean gray values of head and tail are used to locate the head of worm accurately. Next, the worm skeleton is extracted and divided into equal parts. The angle formulas are used to calculate the bending angle of the head of worm. Finally, the number of head thrashes is counted according to the bending angle of the head in each frame. The robustness of the proposed algorithm is evaluated by comparing the counting results of the manual counting. It is proved that the proposed algorithm can recognize the occurrence of head thrashes of C. elegans of different strains. In addition, the difference of the head thrashes behavior of different worm strains is analyzed, it is proved that the relationship between worm head thrashes behavior and lifespan.

Conclusions

A new method is proposed to automatically count the number of head thrashes of worms. This algorithm makes it possible to count the number of head thrashes from the worm videos collected by the automatic tracking system. The proposed algorithm will play an important role in toxicological research and worm vitality research. The code is freely available at https://github.com/hthana/HTC.