Toxics

26 pages, 2267 KiB

Open AccessArticle

Exploring Novel Fungal–Bacterial Consortia for Enhanced Petroleum Hydrocarbon Degradation

by João Paulo Silva Monteiro, André Felipe da Silva, Rubens Tadeu Delgado Duarte and Admir José Giachini

Toxics 2024, 12(12), 913; https://doi.org/10.3390/toxics12120913 - 17 Dec 2024

Abstract

Bioremediation, involving the strategic use of microorganisms, has proven to be a cost-effective alternative for restoring areas impacted by persistent contaminants such as polycyclic aromatic hydrocarbons (PAHs). In this context, the aim of this study was to explore hydrocarbon-degrading microbial consortia by prospecting [...] Read more.

Bioremediation, involving the strategic use of microorganisms, has proven to be a cost-effective alternative for restoring areas impacted by persistent contaminants such as polycyclic aromatic hydrocarbons (PAHs). In this context, the aim of this study was to explore hydrocarbon-degrading microbial consortia by prospecting native species from soils contaminated with blends of diesel and biodiesel (20% biodiesel/80% diesel). After enrichment in a minimal medium containing diesel oil as the sole carbon source and based on 16S rRNA, Calmodulin and β-tubulin gene sequencing, seven fungi and 12 bacteria were identified. The drop collapse test indicated that all fungal and four bacterial strains were capable of producing biosurfactants with a surface tension reduction of ≥20%. Quantitative analysis of extracellular laccase production revealed superior enzyme activity among the bacterial strains, particularly for Stenotrophomonas maltophilia P05R11. Following antagonistic testing, four compatible consortia were formulated. The degradation analysis of PAHs and TPH (C5–C40) present in diesel oil revealed a significantly higher degradation capacity for the consortia compared to isolated strains. The best results were observed for a mixed bacterial-fungal consortium, composed of Trichoderma koningiopsis P05R2, Serratia marcescens P10R19 and Burkholderia cepacia P05R9, with a degradation spectrum of ≥91% for all eleven PAHs analyzed, removing 93.61% of total PAHs, and 93.52% of TPH (C5–C40). Furthermore, this study presents the first report of T. koningiopsis as a candidate for bioremediation of petroleum hydrocarbons. Full article

(This article belongs to the Section Toxicity Reduction and Environmental Remediation)

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Graphical abstract

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Dendrogram constructed from the BOX-PCR data profile of 12 bacterial isolates. The UPGMA method was used based on the similarity matrix. At 58% similarity, the isolates were grouped into 5 clusters. Full article ">Figure 2
Results of screening for biosurfactant-producing isolates. Classification into groups according to Scott–Knott statistical analysis, where different letters indicate significant difference between the means of the treatments; p-value < 0.0001. Full article ">Figure 3
Monitoring extracellular laccase activity for fungal species. Full article ">Figure 4
Monitoring laccase extracellular activity and microbial growth for bacterial species. Comparison of enzymatic activity relative to bacterial growth, measured by a spectrophotometer at 600 nm. Full article ">Figure 5
Efficiency of hydrocarbon degradation by individual strains and consortia. p-value < 0.05 according to ANOVA statistical analysis; mixed fungi-bacteria consortia FFB1 (Trichoderma koningiopsis P05R2, Penicillium Janthinellum P05R3, and Serratia marcescens P10R19), bacteria consortia BB1 (Stenotrophomonas maltophilia P05R11 and S. marcescens P10R19), fungi consortia FF1 (T. koningiopsis P05R2 and P. Janthinellum P05R3), mixed bacteria-fungi consortia FBB1 (T. koningiopsis P05R2, S. marcescens P10R19 and Burkholderia cepacia P05R9), individual fungal strain T. koningiopsis P05R2, individual fungal strain P. Janthinellum P05R3, individual bacterial strain S. marcescens P10R19, and individual bacterial strain S. maltophilia P05R11 are presented. Full article ">

17 pages, 4274 KiB

Open AccessArticle

Neurotransmitter Metabolic Disturbance in Methamphetamine Abusers: Focus on Tryptophan and Tyrosine Metabolic Pathways

by Xi Wang, Weilan Wu, Jing Liu, Miaoyang Hu, Jie Cheng, Jianping Xiong, Xufeng Chen, Rong Gao and Jun Wang

Toxics 2024, 12(12), 912; https://doi.org/10.3390/toxics12120912 - 16 Dec 2024

Abstract

Methamphetamine (METH) abuse disrupts the homeostasis of neurotransmitter (NT) metabolism, contributing to a wide range of neurological and psychological disorders. However, the specific effects of METH on NT metabolism, particularly for the tryptophan (TRP) and tyrosine (TYR) metabolic pathways, remain poorly understood. In [...] Read more.

Methamphetamine (METH) abuse disrupts the homeostasis of neurotransmitter (NT) metabolism, contributing to a wide range of neurological and psychological disorders. However, the specific effects of METH on NT metabolism, particularly for the tryptophan (TRP) and tyrosine (TYR) metabolic pathways, remain poorly understood. In this study, serum samples from 78 METH abusers and 79 healthy controls were analyzed using Ultra-High-Performance Liquid Chromatography with Tandem Mass Spectrometry (UHPLC-MS/MS). A total of 41 substances, primarily from the TRP and TYR metabolic pathways, were detected and subjected to multivariate analysis. Principal Component Analysis (PCA) and Partial Least Squares Discriminant Analysis (PLS-DA) revealed a significant separation of serum metabolites between METH abusers and controls, encompassing the disturbance of serotonergic, kynurenic, and microbial metabolism. In the serotonergic pathway, METH significantly reduced melatonin (MLT) levels and impaired the conversion of serotonin (5-HT) to N-acetylserotonin (NAS), a key precursor of MLT. In the kynurenic pathway, METH promoted a shift to the toxic metabolic pathway, evidenced by elevated levels of 3-hydroxykynurenine (3-HK) and quinolinic acid (QA). Furthermore, microbial metabolic pathway-related indole and its derivatives were markedly suppressed in METH abusers. Gender-specific differences were also observed, with NT metabolism in TRP and TYR pathways showing more pronounced alterations in male or female subgroups. Therefore, the current study provides a comprehensive overview of the disturbance in TRP- and TYR-associated NT metabolism caused by METH abuse and highlights NT metabolism as a promising therapeutic target for METH-induced neural and psychiatric disorders. Full article

(This article belongs to the Section Neurotoxicity)

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PCA of the NTs and their metabolites in the serum of METH abusers and healthy controls. (A) Nonsupervised PCA score plot. (B) PLS-DA score plot. (C) OPLS-DA score plot. Red triangles represent the METH abusers’ serum metabolomes; blue dots represent the healthy controls’ serum metabolomes. (D) Permutation test. It verifies the prediction ability of the OPLS-DA model. p values of <0.05 were considered statistically significant. The permutation number was set to 100. (E) VIP plot of the serum metabolomes. VIP > 0.8. (F) Volcano plot. Red dots: upregulated metabolites; blue dots: downregulated metabolites; gray dots: no obviously affected metabolites. Full article ">Figure 2
The changed serum NTs and the dynamic metabolism of the TRP–kynurenic pathway in METH abusers. (A) Pathway schematic of TRP–kynurenic metabolism. Black arrows show the host pathway; blue arrows show the microbial pathway. Host enzymes with genomic evidence are marked in red; microbial enzymes with genomic evidence are marked in green. (B) Differences in absolute concentrations (ng/mL) of TRP–kynurenic metabolites and the statistically significant ratios in the TRP–kynurenic pathway. C, healthy controls. M, METH abusers. * p < 0.05; ** p < 0.01. Full article ">Figure 3
The changed serum NTs and the dynamic metabolism of the TRP–serotonergic pathway in METH abusers. (A) Pathway schematic of TRP–serotonergic metabolism. Black arrows indicate the host degradation pathway; host enzymes with genomic evidence are marked in red. (B) Differences in absolute concentrations (ng/mL) of TRP–serotonergic metabolites and the statistically significant ratios in the TRP–serotonergic pathway. C, healthy controls. M, METH abusers. * p < 0.05; ** p < 0.01. Full article ">Figure 4
The changed serum NTs and the dynamic metabolism of the TRP–microbial metabolic pathway in METH abusers. (A) Pathway schematic of TRP–microbial metabolism. Black arrows show the host pathway; blue arrows show the microbial pathway. Host enzymes with genomic evidence are marked in red; microbial enzymes with genomic evidence are marked in green. (B) Differences in absolute concentrations (ng/mL) of TRP–microbial metabolism and the statistically significant ratios in the TRP–microbial metabolic pathway. C, healthy controls. M, METH abusers. * p < 0.05; ** p < 0.01. Full article ">Figure 5
The changed serum NTs and the dynamic metabolism of the TYR–dopamine pathway in METH abusers. (A) Pathway schematic of TYR–dopamine metabolism. Black arrows indicate the host degradation pathway; host enzymes with genomic evidence are marked in red. (B,C) Differences in absolute concentrations (ng/mL) of TYR–dopamine metabolism, other amino acid NTs, and the statistically significant ratios. C, healthy controls. M, METH abusers. * p < 0.05; ** p < 0.01. Full article ">Figure 6
ROC curves distinguishing the controls and the METH abusers. Model 1 contained the TRP–microbial metabolic pathway. Model 2 contained the TRP–kynurenic pathway. Model 3 contained the TRP–serotonergic pathway. Full article ">Figure 7
Alterations in NTs and neuroactive metabolites from the t-test in METH abusers of different genders. (A,B) Heatmaps of statistically significant metabolites from the t-test in male and female METH abusers. C, healthy controls. M, METH abusers. hrM, METH abusers of higher exposure. hM, METH abusers of high exposure. mM, METH abusers of medium exposure. lM, METH abusers of low exposure. (C) Venn plot that illustrates differences in serum metabolites between male and female METH abusers, with overlapping areas indicating shared changes caused by METH use in both genders. Full article ">

17 pages, 1935 KiB

Open AccessArticle

Exogenously Applied Triacontanol Mitigates Cadmium Toxicity in Vigna radiata L. by Optimizing Growth, Nutritional Orchestration, and Metal Accumulation

by Saba Mudassar, Shakil Ahmed, Rehana Sardar, Nasim Ahmad Yasin, Muhammad Jabbar and Maximilian Lackner

Toxics 2024, 12(12), 911; https://doi.org/10.3390/toxics12120911 - 14 Dec 2024

Abstract

Cadmium (Cd) is one of the foremost phytotoxic elements. Its proportion in agricultural soil is increasing critically due to anthropogenic activities. Cd stress is a major crop production threat affecting food security globally. Triacontanol (TRIA) is a phytohormone that promotes growth, development, and [...] Read more.

Cadmium (Cd) is one of the foremost phytotoxic elements. Its proportion in agricultural soil is increasing critically due to anthropogenic activities. Cd stress is a major crop production threat affecting food security globally. Triacontanol (TRIA) is a phytohormone that promotes growth, development, and metabolic processes in plants. The current study explicates the mitigation of Cd toxicity in Vigna radiata L. (mung bean) seedlings through the application of TRIA by a seed priming technique under Cd stress. The role of TRIA in improving metabolic processes to promote Vigna radiata (mung bean, green gram) vegetative growth and performance under both stressed and unstressed conditions was examined during this study. To accomplish this, three doses of TRIA (10, 20, and 30 µmol L⁻¹) were used to pretreat V. radiata seeds before they were allowed to grow for 40 days in soil contaminated with 20 mg kg⁻¹ Cd. Cd stress lowered seed germination, morphological growth, and biomass in V. radiata plants. The maximum root and shoot lengths, fresh and dry weights of roots, and shoot and seed germination rates were recorded for TRIA2 compared with those of TRIA1 and TRIA3 under Cd stress. In Cd-stressed V. radiata plants, TRIA2 increased the content of chlorophyll a (2.1-fold) and b (3.1-fold), carotenoid (4.3-fold), total chlorophyll (3.1-fold), and gas exchange attributes, such as the photosynthetic rate (2.9-fold), stomatal conductance (6.0-fold), and transpiration rate (3.5-fold), compared with those in plants treated with only Cd. TRIA seed priming increased nutrient uptake (K¹⁺, Na¹⁺, Mg²⁺, and Zn²⁺), total phenolic content, total soluble protein content, and DPPH (2,2-diphenyl-1-picrylhydrazyl) activity. Additionally, TRIA2 significantly reduced the quantity of Cd in the plants (3.0-fold) and increased the metal tolerance index (6.6-fold) in plants contrasted with those in the Cd-treated plants. However, TRIA2 promoted plant growth and biomass production by lowering Cd-induced stress through modifying the plant antioxidant machinery and reducing oxidative stress. The improved yield characteristics of V. radiata seedlings treated with TRIA suggest that exogenous TRIA may be used to increase plant tolerance to Cd stress. Full article

(This article belongs to the Special Issue Cadmium and Trace Elements Toxicity)

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Effect of TRIA and Cd on proline and total soluble protein content of V. radiata. Values demonstrate means ± SE of four replicates (n = 4). Non-identical letters over error bars exhibit significant differences between the treatments at p ≤ 0.05. C = control, Cd = 20 mg kg−1 Cd, TRIA1 = 10 µM L−1 TRIA, TRIA2 = 20 µM L−1 TRIA, TRIA3 = 30 µM L−1 TRIA. Full article ">Figure 2
Effect of TRIA and Cd on photosynthetic rate, stomatal conductance, and transpiration rate of V. radiata. Values demonstrate means ± SE of four replicates (n = 4). Non-identical letters over error bars exhibit significant differences between the treatments at p ≤ 0.05. C = control, Cd = 20 mg kg−1 Cd, TRIA1 = 10 µM L−1 TRIA, TRIA2 = 20 µM L−1 TRIA, TRIA3 = 30 µM L−1 TRIA. Full article ">Figure 3
Effect of TRIA and Cd on DDPH and total phenolic content of V radiata. Values demonstrate means ± SE of four replicates (n = 4). Non-identical letters over error bars exhibit significant differences between the treatments at p ≤ 0.05. C = control, Cd = 20 mg kg−1 Cd, TRIA1 = 10 µM L−1 TRIA, TRIA2 = 20 µM L−1 TRIA, TRIA3 = 30 µM L−1 TRIA. Full article ">Figure 4
Pearson correlation for V. radiata under TRIA and Cd affect. Different abbreviated forms shown in figure as follows: Zn (Zn concentration in shoots), Mg (Mg concentration in shoots), k (K concentration in shoots), Na (Na concentration in shoots), Chl (chlorophyll), RL (root length), SL (shoot length), LA (leaf area), NP (net photosynthesis), SC (stomatal conductance), Caro (carotenoid content), Pro (protein content), Germ (germination percentage), MTI (metal tolerance index), AC (accumulation factor), Prol (proline concentration), Phe (phenolic level), NOL (number of leaves), SFW (shoot fresh weight), RFW (shoot fresh weight), RDW (root dry weight), SDW (shoot dry weight), ROT (rate of transpiration). Full article ">Figure 5
Loading plots of principal component analysis (PCA) demonstrated a relation between physiological parameters and growth under TRIA treatment and Cd on Vigna radiate L. Various abbreviations used in the figures are as follows: Zn (Zn amount in shoots), Chl (chlorophyll concentration), RL (length of root), SL (length of shoot), LA (leaf area), NP (net photosynthesis), TR (rate of transpiration), SC (stomatal conductance), Caro (carotenoid concentration), pro (protein), MTI (metal tolerance index), AC (accumulation factor), Prol (proline concentration), Phe (phenolic content), Ger (percentage of germination). Full article ">

18 pages, 5075 KiB

Open AccessArticle

Integrative Analysis of Pharmacology and Transcriptomics Predicts Resveratrol Will Ameliorate Microplastics-Induced Lung Damage by Targeting Ccl2 and Esr1

by Yadong Zhang, Jingyi Ren, Siqi Zhu, Zihao Guo, Huanting Pei, Xiaoya Sun, Jiarui Wu, Weijie Yang, Jinshi Zuo and Yuxia Ma

Toxics 2024, 12(12), 910; https://doi.org/10.3390/toxics12120910 - 14 Dec 2024

Abstract

Background: Microplastics (MPs) are ubiquitous on earth, posing a growing threat to human health. Previous studies have shown that the lung is a primary organ for MPs exposure. Resveratrol (RES) is a common dietary polyphenol that exhibits anti-inflammatory and antioxidant effects. However, whether [...] Read more.

Background: Microplastics (MPs) are ubiquitous on earth, posing a growing threat to human health. Previous studies have shown that the lung is a primary organ for MPs exposure. Resveratrol (RES) is a common dietary polyphenol that exhibits anti-inflammatory and antioxidant effects. However, whether RES exerts a protective effect against MPs-induced lung damage is still unknown. Methods: The targets of RES were retrieved from five databases. Differentially expressed genes (DEGs) were identified through comprehensive bioinformatic analysis. Multiple algorithms were employed to screen for the core targets. Ultimately, molecular docking analysis and molecular dynamics (MD) simulations were utilized to confirm the binding affinity between RES and the core targets. Results: In total, 1235 DEGs were identified in the transcriptomes. After removing duplicates, a total of 739 RES targets were obtained from five databases, and 66 of these targets intersected with DEGs. The potential core targets (Esr1, Ccl2) were further identified through topological analysis and machine learning. These findings were subsequently verified by molecular docking and MD simulations. Conclusions: This study demonstrated that RES may mitigate lung injury induced by MPs by targeting Esr1 and Ccl2. Our research offers a novel perspective on the prevention and treatment of MPs-induced lung injury. Full article

(This article belongs to the Special Issue Health Effects and Toxicology Studies of Emerging Contaminants)

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29 pages, 3426 KiB

Open AccessReview

Microplastics as an Emerging Potential Threat: Toxicity, Life Cycle Assessment, and Management

by Sameh S. Ali, Mohammed Hussein M. Alsharbaty, Rania Al-Tohamy, Maha A. Khalil, Michael Schagerl, Majid Al-Zahrani and Jianzhong Sun

Toxics 2024, 12(12), 909; https://doi.org/10.3390/toxics12120909 - 14 Dec 2024

Abstract

The pervasiveness of microplastics (MPs) in terrestrial and aquatic ecosystems has become a significant environmental concern in recent years. Because of their slow rate of disposal, MPs are ubiquitous in the environment. As a consequence of indiscriminate use, landfill deposits, and inadequate recycling [...] Read more.

The pervasiveness of microplastics (MPs) in terrestrial and aquatic ecosystems has become a significant environmental concern in recent years. Because of their slow rate of disposal, MPs are ubiquitous in the environment. As a consequence of indiscriminate use, landfill deposits, and inadequate recycling methods, MP production and environmental accumulation are expanding at an alarming rate, resulting in a range of economic, social, and environmental repercussions. Aquatic organisms, including fish and various crustaceans, consume MPs, which are ultimately consumed by humans at the tertiary level of the food chain. Blocking the digestive tracts, disrupting digestive behavior, and ultimately reducing the reproductive growth of entire living organisms are all consequences of this phenomenon. In order to assess the potential environmental impacts and the resources required for the life of a plastic product, the importance of life cycle assessment (LCA) and circularity is underscored. MPs-related ecosystem degradation has not yet been adequately incorporated into LCA, a tool for evaluating the environmental performance of product and technology life cycles. It is a technique that is designed to quantify the environmental effects of a product from its inception to its demise, and it is frequently employed in the context of plastics. The control of MPs is necessary due to the growing concern that MPs pose as a newly emergent potential threat. This is due to the consequences of their use. This paper provides a critical analysis of the formation, distribution, and methods used for detecting MPs. The effects of MPs on ecosystems and human health are also discussed, which posed a great challenge to conduct an LCA related to MPs. The socio-economic impacts of MPs and their management are also discussed. This paper paves the way for understanding the ecotoxicological impacts of the emerging MP threat and their associated issues to LCA and limits the environmental impact of plastic. Full article

(This article belongs to the Special Issue Emissions, Environmental Behavior, Pollution Distribution, Modeling, and Risk Assessment of Persistent Organic Pollutants (POPs))

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20 pages, 1292 KiB

Open AccessReview

Unmasking the Invisible Threat: Biological Impacts and Mechanisms of Polystyrene Nanoplastics on Cells

by Wenxia Bu, Ye Cui, Yueyuan Jin, Xuehai Wang, Mengna Jiang, Ruiyao Huang, JohnPaul Otuomasiri Egbobe, Xinyuan Zhao and Juan Tang

Toxics 2024, 12(12), 908; https://doi.org/10.3390/toxics12120908 - 14 Dec 2024

Abstract

Polystyrene nanoplastics (PS-NPs), a pervasive component of plastic pollution, have emerged as a significant environmental and health threat due to their microscopic size and bioaccumulative properties. This review systematically explores the biological effects and mechanisms of PS-NPs on cellular systems, encompassing oxidative stress, [...] Read more.

Polystyrene nanoplastics (PS-NPs), a pervasive component of plastic pollution, have emerged as a significant environmental and health threat due to their microscopic size and bioaccumulative properties. This review systematically explores the biological effects and mechanisms of PS-NPs on cellular systems, encompassing oxidative stress, mitochondrial dysfunction, DNA damage, inflammation, and disruptions in autophagy. Notably, PS-NPs induce multiple forms of cell death, including apoptosis, ferroptosis, necroptosis, and pyroptosis, mediated through distinct yet interconnected molecular pathways. The review also highlights various factors that influence the cytotoxicity of PS-NPs, such as particle size, surface modifications, co-exposure with other pollutants, and protein corona formation. These complex interactions underscore the extensive and potentially hazardous impacts of PS-NPs on cellular health. The findings presented here emphasize the need for continued research on the mechanisms underlying PS-NP toxicity and the development of effective strategies for mitigating their effects, thereby informing regulatory frameworks aimed at minimizing environmental and biological risks. Full article

(This article belongs to the Section Exposome Analysis and Risk Assessment)

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15 pages, 1818 KiB

Open AccessArticle

Application of Phosphate-Based Binders for the Stabilization and Solidification of Metal-Contaminated Soil: Mechanisms and Efficacy Evaluation

by Shiliang Xu, Ayesha Imtiyaz Cheema, Yunhui Zhang and Bin Dong

Toxics 2024, 12(12), 907; https://doi.org/10.3390/toxics12120907 - 13 Dec 2024

Abstract

At present, contamination due to toxic metals is a global concern. The management of problems caused by heavy metals relies on stabilization/solidification, which is the most effective technique for the control of metal pollution in soil. This study examined the immobilization efficiency of [...] Read more.

At present, contamination due to toxic metals is a global concern. The management of problems caused by heavy metals relies on stabilization/solidification, which is the most effective technique for the control of metal pollution in soil. This study examined the immobilization efficiency of various phosphate-based binders (Na₃PO₄, Na₂HPO₄, NaH₂PO₄), in addition to ordinary Portland cement (OPC), MgO, and CaO, for the stabilization of multi-metal-contaminated soils. Moreover, this study focused on the leachability of copper, nickel, zinc, lead, cadmium, and manganese (Cu, Ni, Zn, Pb, Cd, Mn, respectively) over different time periods and with different concentrations. Batch leaching experiments were conducted to determine the leaching ratios and percentages of the various metal concentrations, along with measuring the pH values of the leachates. Our results indicate that the use of OPC was validated due to its superior immobilization performance across all metals present in the soil, but particularly with regard to metals in high concentrations. This was due to the formation of stable hydroxides and the high pH values, which assisted in abating the metals’ solubility. Additionally, phosphate-based binders, despite being environmentally favorable, were found to be less effective, particularly for Pb and Cu, and the leaching results exceeded non-hazardous waste limits. MgO showed reasonable immobilization results but was less effective compared to OPC; on the other hand, CaO exhibited increased leaching over time. Therefore, the present research serves primarily to highlight that OPC is more suitable for soil remediation at industrial sites and in the construction of infrastructure. Meanwhile, phosphate-based binders are shown to be more appropriate for eco-friendly, non-load-bearing applications. Full article

(This article belongs to the Section Toxicity Reduction and Environmental Remediation)

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23 pages, 3699 KiB

Open AccessArticle

Multigenerational Consequences of Prenatal Exposure to Benzophenone-3 Demonstrate Sex- and Region-Dependent Neurotoxic and Pro-Apoptotic Effects in Mouse Brain

by Karolina Przepiórska-Drońska, Andrzej Łach, Bernadeta Angelika Pietrzak-Wawrzyńska, Joanna Rzemieniec, Małgorzata Kajta, Agnieszka Wawrzczak-Bargieła, Wiktor Bilecki, Karolina Noworyta and Agnieszka Wnuk

Toxics 2024, 12(12), 906; https://doi.org/10.3390/toxics12120906 - 13 Dec 2024

Abstract

Benzophenone-3 (BP-3), commonly used as a UV filter in personal care products and as a stabilizer, is an alleged endocrine disruptor with potential neurodevelopmental impacts. Despite its abundance in the environment, the studies on its effect on brain development are scarce, especially in [...] Read more.

Benzophenone-3 (BP-3), commonly used as a UV filter in personal care products and as a stabilizer, is an alleged endocrine disruptor with potential neurodevelopmental impacts. Despite its abundance in the environment, the studies on its effect on brain development are scarce, especially in terms of multigenerational impact. In this work, for the first time, we examined neurotoxic and pro-apoptotic effects of BP-3 on mouse brain regions (cerebral cortex and hippocampus) in both the first (F₁) and second (F₂) generations after maternal exposure to environmentally relevant BP-3 levels. We found disregulated markers of cell damage (LDH, H₂O₂, caspase-3 and -8) and observed increased expression of pro-apoptotic Fas/FAS or Fasl/FASL. BP-3 exposure disrupted the BAX/BCL2 pathway, showing stronger effects in the F₁ than in the F₂ generation, with a dominance of extrinsic pathway (FAS, FASL, caspase-8) over intrinsic one (BAX, BCL2), suggesting that BP-3-induced apoptosis primarily operates via the extrinsic pathway and could impair brain homeostasis across generations. This study underscores the potential of BP-3 to increase multigenerational risks associated with disrupted neurodevelopment and highlights the importance of understanding its long-term neurotoxic effects. Full article

(This article belongs to the Special Issue The Effects of Environmental Exposures on Fetal Growth, Children Development and the Corresponding Mechanisms)

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14 pages, 2155 KiB

Open AccessArticle

Integration of Copper Toxicity Mechanisms in Raphidocelis subcapitata: Advancing Insights at Environmentally Relevant Concentrations

by Manuela D. Machado and Eduardo V. Soares

Toxics 2024, 12(12), 905; https://doi.org/10.3390/toxics12120905 - 13 Dec 2024

Abstract

This work aimed to characterize the impact of copper (Cu), at environmentally relevant concentrations, using the freshwater microalga Raphidocelis subcapitata. Algae were incubated with 33 or 53 µg/L Cu, in OECD medium, and toxic impacts were evaluated over 72 h, using different [...] Read more.

This work aimed to characterize the impact of copper (Cu), at environmentally relevant concentrations, using the freshwater microalga Raphidocelis subcapitata. Algae were incubated with 33 or 53 µg/L Cu, in OECD medium, and toxic impacts were evaluated over 72 h, using different cellular and biochemical biomarkers. The exposure to 33 µg/L Cu had an algistatic effect: slowing growth and reducing algal population (53%, at 72 h) without compromising the cell membrane. This Cu concentration promoted a transient reduction in chlorophyll a (chla) content and typical markers of oxidative stress: increased levels of reactive oxygen species (ROS), augmented catalase (CAT) activity, and lipid peroxidation (malondialdehyde, MDA). Algae exposed to 53 µg/L Cu, suffered a severe effect with a 93% reduction in the number of cells, 50% decrease in chla content, and diminished (17%) maximum photochemical quantum yield of PSII (F_v/F_m). This population also presented increased levels of ROS and MDA, 33 and 20 times higher than the control, respectively, at 72 h, augmented CAT activity, and permeabilized cell membrane (5%, at 72 h). These findings provide valuable insights into Cu toxicity in aquatic ecosystems, highlighting the biochemical and physiological impacts at environmentally relevant concentrations. Full article

(This article belongs to the Section Ecotoxicology)

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Figure 1
Effect of Cu on R. subcapitata proliferation capacity. Evolution of algal population on OECD medium in the absence (control) or the presence of Cu. Data are presented as mean values ± SD (error bars). At each time, the statistical difference between control and Cu-treated cells was tested using unpaired Student’s t-test; the means with (*) are significantly different from the control (p < 0.05, n = 6). Full article ">Figure 2
Impact of Cu on R. subcapitata chlorophyll a content. Data are presented as mean values ± SD; mean values with different letters are significantly different (p < 0.05, n = 5, Kruskal–Wallis test, Dunn’s post hoc test). Full article ">Figure 3
Influence of Cu on R. subcapitata photosynthetic activity evaluated by pulse-amplitude-modulation fluorescence assay. (A) Maximum photochemical quantum yield of PSII (Fv/Fm). (B) Effective photochemical quantum yield of PSII (ΦPSII). (C) Electron transport rate (ETR). (D) Non-photochemical quenching (NPQ). Data are presented as mean values ± SD. At each time, the statistical difference between control and Cu-treated cells was tested using unpaired Student’s t-test; the means with (*) are significantly different from the control (p < 0.05, n = 5). Full article ">Figure 4
ROS accumulation and antioxidant activity of R. subcapitata cells exposed to Cu. (A) Reactive oxygen species (ROS) production. (B) Visualization of the intracellular accumulation of ROS (green cells) by epifluorescence microscopy and using the H2DCFDA probe on algae not exposed or exposed to Cu for 72 h. (C) Carotenoids content. (D) Superoxide dismutase (SOD) activity. (E) Catalase (CAT) activity. Data are presented as mean values ± SD. At each time, the statistical difference between control and Cu-treated cells was tested using unpaired Student’s t-test; the means with (*) are significantly different from the control (p < 0.05; n = 4). Full article ">Figure 5
Lipid peroxidation and loss of cell membrane integrity of R. subcapitata exposed to Cu. (A) Malondialdehyde (MDA) content (lipid peroxidation). (B) Loss of plasma membrane integrity. Data are presented as mean values ± SD. At each time, the statistical difference between control and Cu-treated cells was tested using unpaired Student’s t-test; the means with (*) are significantly different from the control (p < 0.05; n = 3 for lipid peroxidation and n = 5 for cell membrane integrity). Full article ">Figure 6
Proposal of the mechanism of action (toxicity pathway) of Cu, at environmentally relevant concentrations on the freshwater alga R. subcapitata based on the results here presented and previous works [<a href="#B13-toxics-12-00905" class="html-bibr">13</a>,<a href="#B23-toxics-12-00905" class="html-bibr">23</a>,<a href="#B27-toxics-12-00905" class="html-bibr">27</a>]. Variations in cellular responses are symbolized by “+” or “−“ for an increase or decrease, respectively. CAT—catalase, GSH—reduced glutathione, ROS—reactive oxygen species. Full article ">

9 pages, 623 KiB

Open AccessArticle

Ecotoxicity of a Representative Urban Mixture of Rare Earth Elements to Hydra vulgaris

by Joelle Auclair, Chantale André, Eva Roubeau-Dumont and François Gagné

Toxics 2024, 12(12), 904; https://doi.org/10.3390/toxics12120904 - 12 Dec 2024

Abstract

Rare earth elements (REEs) are considered as emerging contaminants due to their use in the fabrication process of current technologies. As such, their aquatic toxicity, especially as a mixture, is not well understood, as it has been scarcely investigated. The purpose of this [...] Read more.

Rare earth elements (REEs) are considered as emerging contaminants due to their use in the fabrication process of current technologies. As such, their aquatic toxicity, especially as a mixture, is not well understood, as it has been scarcely investigated. The purpose of this study was to shed light on the sublethal and lethal toxicity of a realistic mixture of five REE in Hydra vulgaris. The REE mixture was composed of five elements (Gd, Ce, Nd, Y and Dy, with a total REE concentration of 0.137 µg/L = 1× concentration) that were found in six municipal effluents in Canada at the same concentration ratios. The organisms were exposed to increasing concentrations (0.5, 1, 5, 10, 25, 50 and 100×) of the mixture for 96 h at 20 °C. The lethal and sublethal toxicities were evaluated by morphological changes and the gene expression (mRNA) involved in oxidative stress, damaged protein salvaging (autophagy for the reabsorption of damaged proteins), regeneration, neural activity and DNA repair of oxidatively damaged DNA. The data revealed that the total REE concentration of the environmental mixture was well below the lethal concentrations of the individual REEs, which occur generally at concentrations > 200 µg/L. This study proposes a novel gene transcription set to investigate the mode of action where gene expression changes occurred at concentrations below those reported in municipal effluents, suggesting long-term toxic effects in hydras close to municipal effluent discharges. This suggests that the release of REEs by municipal/hospital (for Gd) effluents should be more closely monitored. Full article

(This article belongs to the Section Ecotoxicology)

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11 pages, 238 KiB

Open AccessArticle

A Health Risk Assessment of Workers Exposed to Organic Paint Solvents Used in the Korean Shipbuilding Industry

by Sue-Ji Seo, Sae-Mi Shin, Wonsuck Yoon and Sang-Hoon Byeon

Toxics 2024, 12(12), 903; https://doi.org/10.3390/toxics12120903 - 11 Dec 2024

Abstract

In the shipbuilding industry, during the painting process, workers are exposed to various substances in paint, including organic solvents that can adversely affect their health. Most workplace exposures to organic solvents involve mixtures of organic compounds. Therefore, in this study, the hazard quotient [...] Read more.

In the shipbuilding industry, during the painting process, workers are exposed to various substances in paint, including organic solvents that can adversely affect their health. Most workplace exposures to organic solvents involve mixtures of organic compounds. Therefore, in this study, the hazard quotient (HQ) and hazard index (HI) were derived using data from the Workplace Environmental Monitoring Program in Korea for six organic solvents (xylene, n-butanol, ethylbenzene, isobutyl alcohol, toluene, and methylisobutyl ketone [MIBK]) commonly used in the steel shipbuilding industry. The non-carcinogenic risk was assessed using Monte Carlo simulations, and sensitivity analysis was performed using the Spearman rank correlation coefficient with the R program. The HI for neurotoxicity and developmental toxicity exceeded 1 in the 25th and 75th percentile, respectively. According to the sensitivity analysis, the HI for neurotoxicity was correlated with the concentration of xylene and its exposure duration, whereas that for developmental toxicity was correlated with the concentration of ethylbenzene and MIBK and their exposure duration. This study investigated the health risks posed by organic solvents among workers involved in the painting process of shipbuilding. Additional research on percutaneous exposure to organic solvents and a detailed process analysis are needed. Full article

(This article belongs to the Section Exposome Analysis and Risk Assessment)

21 pages, 8373 KiB

Open AccessArticle

Analysis of Acute and Short-Term Fluoride Toxicity in Zebrafish Embryo and Sac–Fry Stages Based on Bayesian Model Averaging

by Tingxu Jin, Xiumei Yang, Yuanhui Zhu, Cheng Yan, Rui Yan, Qianlei Yang, Hairu Huang and Yan An

Toxics 2024, 12(12), 902; https://doi.org/10.3390/toxics12120902 - 11 Dec 2024

Abstract

Acute and short-term toxicity tests are foundational to toxicology research. These tests offer preliminary insights into the fundamental toxicity characteristics of the chemicals under evaluation and provide essential data for chronic toxicity assessments. Fluoride is a common chemical in aquatic environments; however, the [...] Read more.

Acute and short-term toxicity tests are foundational to toxicology research. These tests offer preliminary insights into the fundamental toxicity characteristics of the chemicals under evaluation and provide essential data for chronic toxicity assessments. Fluoride is a common chemical in aquatic environments; however, the findings of toxicological data, such as LC₅₀ for aquatic organisms, often exhibit inconsistency. Consequently, this study employed zebrafish as a model organism during their early life stages to assess the acute and short-term toxicity of fluoride exposure. Bayesian model averaging was utilized to calculate the LC₅₀/EC₅₀ values and establish baseline concentrations. The results indicated a dose–response relationship between water fluoride concentration and harmful outcomes. The 20 mg/L group was identified as the lowest observed adverse effect level (LOAEL) for the majority of toxicity indicators and warrants special attention. Based on the BBMD model averages, the LC₅₀ of fluoride for 1 to 5 days post-fertilization (dpf) zebrafish was 147.00, 80.80, 61.25, 56.50, and 37.50 mg/L, while the EC₅₀ of cumulative malformation rate for 5 dpf zebrafish was 59.75 mg/L. As the benchmark response (BMR) increased, both the benchmark concentrations (BMCs) and benchmark dose levels (BMDLs) also increased. The research aims to provide essential data for the development of environmental water guidelines and to mitigate ecological risks associated with fluoride in aquatic ecosystems. Full article

(This article belongs to the Special Issue Molecular Mechanisms of Disease Caused from Environmental Fluoride and Arsenic Exposures)

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16 pages, 974 KiB

Open AccessArticle

Determinants of Indoor NO₂ and PM_2.5 Concentration in Senior Housing with Gas Stoves

by Khafayat Kadiri, David Turcotte, Rebecca Gore, Anila Bello and Susan R. Woskie

Toxics 2024, 12(12), 901; https://doi.org/10.3390/toxics12120901 - 11 Dec 2024

Abstract

Nitrogen dioxide (NO₂) and particulate matter of 2.5 microns (PM_2.5) are air pollutants that impact health, especially among vulnerable populations with respiratory disease. This study identifies factors influencing indoor NO₂ and PM_2.5 in low-income households of older [...] Read more.

Nitrogen dioxide (NO₂) and particulate matter of 2.5 microns (PM_2.5) are air pollutants that impact health, especially among vulnerable populations with respiratory disease. This study identifies factors influencing indoor NO₂ and PM_2.5 in low-income households of older adults with asthma who use gas stoves in Lowell, Massachusetts. Environmental sampling was conducted in 73 homes, measuring NO₂, PM_2.5, fractional stove-use, temperature, and humidity for 5–7 days. Participants were recruited between December 2020 and July 2022. Questionnaires were used to collect data on factors influencing indoor NO₂ and PM_2.5 concentrations. Daily outdoor NO₂ and PM_2.5 concentrations were obtained from a United States Environmental Protection Agency (EPA) monitoring station. Paired t-tests were conducted between indoor and outdoor NO₂ and PM_2.5 concentrations, and linear regression was used to evaluate factors influencing indoor NO₂ and PM_2.5 concentrations. The average indoor concentration for NO₂ and PM_2.5 were 21.8 (GSD = 2.1) ppb and 16.2 (GSD = 2.7) µg/m³, respectively. Indoor NO₂ and PM_2.5 concentrations exceeded outdoor concentrations significantly. In multiple regression models, season and pilot light stove use significantly predicted indoor NO₂. Season and air freshener use for 6–7 days/week significantly predicted indoor PM_2.5. Season-influenced higher indoor concentrations are likely due to reduced ventilation in colder months in the Northeast U.S. Full article

(This article belongs to the Section Air Pollution and Health)

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11 pages, 945 KiB

Open AccessArticle

Identification and Assessment of Toxic Substances in Environmental Justice Cases

by Xiaowei Xu, Dapeng Zhang, Jun Zhang, Zehua Zhao, Jing Hua, Yi Wang, Houhu Zhang and Qi Yu

Toxics 2024, 12(12), 900; https://doi.org/10.3390/toxics12120900 - 11 Dec 2024

Abstract

This study assessed heavy metal contamination in industrial solid waste (S1, S2, S3, and S4) from the Yangtze River Delta region, employing nine risk assessment methods including total content indices (e.g., Igeo, CF) and speciation indices (e.g., ICF, GCF). Four types of industrial [...] Read more.

This study assessed heavy metal contamination in industrial solid waste (S1, S2, S3, and S4) from the Yangtze River Delta region, employing nine risk assessment methods including total content indices (e.g., Igeo, CF) and speciation indices (e.g., ICF, GCF). Four types of industrial solid waste not classified as hazardous but containing heavy metals were analyzed. Key findings revealed significant variability in risk assessments based on chemical speciation versus total content. For example, while S1, S3, and S4 exceeded background levels, S4 showed higher mobility of Pb, Cr (VI), Cu, Ni, and As despite lower overall content. Elements like Cd and Cr (VI) exhibited discrepancies between total content and speciation-based assessments due to low background values and high toxicity. Multi-element indices (DC, RI) indicated higher pollution degrees compared to speciation indices (GCF, GRI). These results underscore the need for integrating multiple assessment methods to accurately evaluate environmental risks in judicial practices. Full article

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12 pages, 2432 KiB

Open AccessArticle

Clonal Integration Promotes the Photosynthesis of Clonal Plant Under Heterogeneous Pb and/or Pyrene Stress

by Yichen Liu, Sunan Xu, Xuemei Li and Lihong Zhang

Toxics 2024, 12(12), 899; https://doi.org/10.3390/toxics12120899 - 11 Dec 2024

Abstract

Clonal plants can support the growth of their ramets in heterogeneous environments through clonal integration between the ramets. However, the role of clonal integration in modulating ramet photosynthesis under toxic stress, especially combined stress, is unclear. This study examines the impact of clonal [...] Read more.

Clonal plants can support the growth of their ramets in heterogeneous environments through clonal integration between the ramets. However, the role of clonal integration in modulating ramet photosynthesis under toxic stress, especially combined stress, is unclear. This study examines the impact of clonal integration on Zoysia japonica under three heterogeneous stresses (Pb, pyrene, and Pb+Pyrene) with two stolon connection conditions (connected and disconnected). Our results show that clonal integration significantly enhances P_N, g_s, C_i, E, and CE while reducing WUE. It also improves ΦPSII, F_v′/F_m′, F_v/F_m, F_v/F₀, and q_P while reducing NPQ. Clonal integration lowers MDA levels, increases SOD activity, and mitigates the decline in CAT and POD activity, resulting in increased biomass under stress. Furthermore, we observed that the synergistic effects of the Pb+Pyrene mixture negatively impacted the adaptability of clonal integration. Our study underscores the role of clonal integration in maintaining photosynthesis and supporting the success of clonal plants in toxic environments. Full article

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Full article ">Figure 1
Experimental design. Connected and disconnected ramets of Zoysia were subjected to heterogeneous Pb and/or pyrene stress. Full article ">Figure 2
Growth parameters in connected and disconnected Zoysia ramets under heterogeneous stresses. Fresh weight (A), SPAD value (B), fresh weight of the whole clone under Pb treatment (C), fresh weight of the whole clone under pyrene treatment (D), and fresh weight of the whole clone under combined Pb+Pyrene treatment (E) graphs are shown. Fresh weights represent the total biomass per pot. Values are mean ± SD for n = 3. Bars with different letters are statistically different at p < 0.05, by LSD test (A,B). NS means not significant and * p < 0.05, by two-tailed Student’s t-test (C–E). Full article ">Figure 3
Photosynthetic parameters in connected and disconnected Zoysia ramets under heterogeneous stresses. PN (A), gs (B), Ci (C), E (D), WUE (E), and CE (F) graphs are shown. Values are mean ± SD for n = 3. Bars with different letters are statistically different at p < 0.05, by LSD test. Full article ">Figure 4
Spider chart of chlorophyll fluorescence parameters in connected and disconnected Zoysia ramets under heterogeneous stresses. Each line represents the average of 3 measurements per treatment. Each parameter is expressed as a fraction relative to the values of CNH (black line with a value 100% = 1). Full article ">Figure 5
Lipid peroxidation and antioxidant enzyme activity in connected and disconnected Zoysia ramets under heterogeneous stresses. MDA content (A), SOD activity (B), CAT activity (C), and POD activity (D) are shown. Values are mean ± SD for n = 3. Bars with different letters are statistically different at p < 0.05, by LSD test. Full article ">

11 pages, 1984 KiB

Open AccessArticle

Short-Term Effects of NO₂ Exposure on Hospitalization for Chronic Kidney Disease

by Wancheng Zhang, Ye Ruan and Jianglong Ling

Toxics 2024, 12(12), 898; https://doi.org/10.3390/toxics12120898 - 11 Dec 2024

Abstract

This study investigates the correlation between short-term exposure to nitrogen dioxide (NO₂) and hospitalization for chronic kidney disease (CKD) in Lanzhou, China. A distributed lag nonlinear model (DLNM) was employed to examine the relationship between changes in NO₂ concentration and [...] Read more.

This study investigates the correlation between short-term exposure to nitrogen dioxide (NO₂) and hospitalization for chronic kidney disease (CKD) in Lanzhou, China. A distributed lag nonlinear model (DLNM) was employed to examine the relationship between changes in NO₂ concentration and CKD hospitalizations. Subgroup analyses were conducted to assess the sensitivity of different populations to NO₂ exposure. A total of 35,857 CKD hospitalizations occurred from 1 January 2014 to 31 December 2019. The average daily concentration of NO₂ was 47.33 ± 17.27 µg/m³. A significant exposure response relationship was observed between changes in NO₂ concentration and the relative risk (RR) of CKD hospitalization. At lag0 (the same day) and lag0-1 (cumulative same day and the previous 1 day) to lag0-4 (cumulative same day and the previous 4 days), NO₂ exhibited a harmful effect on CKD hospitalizations, with the maximum effect occurring at lag0-1. For every 10 µg/m³ increase in NO₂ concentration, the RR of CKD hospitalization was 1.034 [95% confidence interval (CI): 1.017, 1.050]. Subgroup analyses revealed that the adverse effects of NO₂ were more pronounced in females and individuals aged ≥65 years. The harmful effects were also more significant during the cold season. In conclusion, short-term NO₂ exposure is associated with an increased relative risk of CKD hospitalization. Continuous efforts to improve air quality are essential to protect public health. Full article

(This article belongs to the Topic The Effect of Particulate Matter and Heat Waves, and the Corresponding Health Management)

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19 pages, 324 KiB

Open AccessReview

A Review on Remediation Technology and the Remediation Evaluation of Heavy Metal-Contaminated Soils

by Lei Xu, Feifei Zhao, Xiangyu Xing, Jianbiao Peng, Jiaming Wang, Mingfei Ji and B. Larry Li

Toxics 2024, 12(12), 897; https://doi.org/10.3390/toxics12120897 - 10 Dec 2024

Abstract

With the rapid development of industry and agriculture, soil contamination has become a significant environmental issue, and the heavy metal contamination of soils is an important part of it. The main methods for the remediation of heavy metal-contaminated soils include physical methods, chemical [...] Read more.

With the rapid development of industry and agriculture, soil contamination has become a significant environmental issue, and the heavy metal contamination of soils is an important part of it. The main methods for the remediation of heavy metal-contaminated soils include physical methods, chemical methods, biological methods, and combined remediation methods have been proposed as research deepens. However, the standards and evaluation methods for the remediation of heavy metal-contaminated soils are still not well-established. This article discusses the sources and contamination status of heavy metals in soils, the advantages and disadvantages of remediation technology for heavy metal-contaminated soils, remediation standards, and post-remediation evaluation methods. It also proposes scientific issues to be addressed in future research and provides an outlook on future development, hoping to assist in subsequent remediation studies of heavy metal-contaminated soils. Full article

18 pages, 4971 KiB

Open AccessArticle

Triptolide Causes Spermatogenic Disorders by Inducing Apoptosis in the Mitochondrial Pathway of Mouse Testicular Spermatocytes

by Jiantao Zhao, Maosheng Cao, Haisheng Yi, Guitian He, Tong Chen, Lingyun Liu, Kaimin Guo, Yin Cao, Chunjin Li, Xu Zhou, Boqi Zhang and Hongliang Wang

Toxics 2024, 12(12), 896; https://doi.org/10.3390/toxics12120896 - 10 Dec 2024

Abstract

Triptolide (TP) is a diterpenoid compound extracted from the traditional Chinese medicinal herb Tripterygium wilfordii. It has antitumor and anti-inflammatory effects and stimulates immunity. However, its serious side effects, especially reproductive toxicity, limit its clinical application. This study employed a testicular injury model [...] Read more.

Triptolide (TP) is a diterpenoid compound extracted from the traditional Chinese medicinal herb Tripterygium wilfordii. It has antitumor and anti-inflammatory effects and stimulates immunity. However, its serious side effects, especially reproductive toxicity, limit its clinical application. This study employed a testicular injury model established by intraperitoneally injecting TP (0.2 mg/kg) in C57BL/6J male mice (age = 7–8 weeks) for 14 days. The control and TP mice’s testicular tissues were subjected to transcriptome sequencing to assess potential testicular damage mechanisms. Based on the transcriptome sequencing results and relevant literature reports, further experiments were performed. In addition, to alleviate triptolide-induced testicular damage, we treated the mice with N-acetyl-L-cysteine (NAC). The acquired data revealed that compared with the control mice, the TP-treated mice’s testes indicated severe damage. Transcriptome sequencing identified differentially expressed genes that showed enrichment in cell differentiation, apoptotic process, cell cycle, glutathione (GSH) metabolism, and the p53 signaling pathway. Furthermore, TUNEL assays and Western blot analysis showed that in the TP mice’s testicular tissues, the spermatocytes had mitochondrial pathway apoptosis as well as abnormal mitochondrial morphology and structure. Triptolide induces oxidative stress in testicular tissue by enhancing pro-oxidative systems and inhibiting antioxidant systems. NAC reduced testicular damage and apoptosis by alleviating TP-induced oxidative stress. This study also employed a GC2 cell line for in-vitro analyses, and the results were consistent with the in vivo experiments. This study provides evidence for alleviating TP’s adverse effects on the male reproductive system for better clinical application. Full article

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Triptolide-induced testicular damage and spermatogenic disorders. (A) The chemical structure of triptolide. (B) A flowchart of medication administration. (C) The epididymal sperm count (n = 5). (D) The size of the testis (a) and organ index (b). (E) H&E staining, the seminiferous tubule diameter, the epithelium height (a), and the tunica albuginea thickness of the testes (b). (F) The relative mRNA level of Sycp3 (n = 4). (G) The Western blot of Sycp3 (n = 3) (a,b). (H) The immunohistochemistry staining of testes. * p < 0.05, ** p < 0.01 vs. control (means ± SEM). Full article ">Figure 2
Transcriptomic analysis of testes. (A) A volcano plot of differential expression genes (DEGs). (B) The number of DEGs. (C) GO enhancement analyses of the DEGs. (D) KEGG enhancement analyses of the DEGs. Full article ">Figure 3
Triptolide caused apoptosis of the mitochondrial pathway in testicular spermatogonia and GC2 cell lines. (A) TUNEL staining of testes. (B) Western blot analysis of Bax, Bcl-2, cleaved-caspase3 (n = 3) (a,b). (C) The cell viability of GC2 cells treated with different concentrations of triptolide. (D) The detection of apoptosis in GC2 cells by flow cytometry (a,b). (E) Western blot analysis of Bax, Bcl-2 (a), and cleaved-caspase3 (n = 3) (b). (F) Flow cytometric analysis was used to examine the mitochondrial membrane potential (MMP) levels in GC2 cells (a,b). (G) The electron microscopic observation of testicular (a) and GC2 cell mitochondria (b). * p < 0.05, ** p < 0.01 vs. control (means ± SEM). Full article ">Figure 4
Triptolide led to oxidative stress in mouse testicular tissue and GC2 cell lines by enhancing the oxidative system and attenuating the antioxidant system (A) The MDA (a) and GSH (b) levels of testicular tissue. (B) The intracellular ROS levels of GC2 cell lines (a,b). (C) The MDA and GSH levels of GC2 cell lines (a,b). (D) The relative mRNA level of Gpx4, Txnd2, Hmox2, Aptx, Lcn2, Romo1 (a), and Cyp11a1 in testicular tissue (n = 4) (b). (E) The relative mRNA level of Gpx4, Hmox2, HO-1, Lcn2 (a), and Jun in GC2 cell lines (n = 3) (b). (F) The molecular docking of TP, Gpx4, Nrf2. * p < 0.05, ** p < 0.01 vs. control (means ± SEM). Full article ">Figure 5
The activation of oxidative stress-mediated apoptosis in the mitochondrial pathway by triptolide caused impaired spermatogenesis in mice. (A) A flowchart of medication administration. (B) The epididymal sperm count (n = 6). (C) The size of the testis (a) and the testis index (b). (D) H&E staining (a), the seminiferous tubule diameter (b), the epithelium height (c), and the tunica albuginea thickness of testes (d). (E) The MDA (a) and GSH (b) levels of testicular tissue. (F) Western blot analysis of Bax, Bcl-2, cleaved-caspase3 of testicular tissues with different treatments (n = 3) (a–e). (G) TUNEL staining of the testes. (H) Relative mRNA levels of Sycp3 (n = 3). (I) Western blot analysis of Sycp3 of testicular tissues with different treatments (n = 3) (a,b). (J) Immunohistochemistry staining of the testes. * p < 0.05, ** p < 0.01 vs. control (means ± SEM). Full article ">Figure 6
The inhibition of oxidative stress alleviates triptolide-induced apoptosis of GC2 cell lines. (A) The cell viability of GC2 cells treated with different concentrations of NAC (1–5 mM). (B) The intracellular ROS levels of GC2 cell lines (a,b). (C) The MDA (a) and GSH (b) levels of GC2 cell lines. (D) Western blot analysis of Bax, Bcl-2, cleaved-caspase3 of GC2 cells with different treatments (n = 3) (a–e). (E) The detection of apoptosis in GC2 cells by flow cytometry (a,b). * p < 0.05, ** p < 0.01 vs. control (means ± SEM). Full article ">

15 pages, 2793 KiB

Open AccessArticle

A Mechanism of Reducing Methane Production During Sewage Sludge Composting by Adding Urea

by Ke Zhang, Haopeng Guo, Yujing Liang, Fuyong Liu, Guodi Zheng, Jun Zhang, Aihua Gao, Nan Liu and Chuang Ma

Toxics 2024, 12(12), 895; https://doi.org/10.3390/toxics12120895 - 10 Dec 2024

Abstract

The study of the effect of the mechanism of urea addition to sewage sludge and sawdust-composting substrates on methane production is still limited. In the present study, the systematic investigation of the effect of urea addition (0.18, 0.9 and 1.8 kg) on methane [...] Read more.

The study of the effect of the mechanism of urea addition to sewage sludge and sawdust-composting substrates on methane production is still limited. In the present study, the systematic investigation of the effect of urea addition (0.18, 0.9 and 1.8 kg) on methane production is discussed through the dynamics of physical properties, enzymes, and the microbial community during composting. The results showed that high urea addition (1.8 kg) suppressed methane production, with a lower rate and a shorter duration of warming in the thermophilic phase, but significantly enhanced cellulase activity, urease, and peroxidase, and promoted the degradation of organic carbon, as well as the loss of nitrogen. A high addition of urea stimulated the growth and reproduction of Sinibacillus, Pseudogracilibacillus, Sporosarcina, and Oceanobacillus. The random forest model indicated that the top six independent determinants of CH₄ emissions were Methanobacterium, temperature, organic matter (OM), Methanospirillum, and NH₄⁺-N. Furthermore, structural equation modeling displayed that NH₄⁺-N, O₂, and pH were the main physicochemical properties affecting CH₄ emissions. Methanobacterium, Methanosarcina, and Methanosphaera were the main archaea, and Bacillaceae were the main bacteria affecting CH₄ emissions. This study provides new insights and a theoretical basis for optimizing urea addition strategies during composting. Full article

(This article belongs to the Section Ecotoxicology)

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Changes in (a) Temperature, (b) pH, (c) OM, (d) O2, (e) CH4 and (f) GI during composting. Full article ">Figure 2
Changes in (a) Temperature, (b) pH, (c) OM and (d) O2 during composting. Full article ">Figure 3
Evolution of enzyme activities of different piles during the composting process. Enzyme legends: (a) cellulase, (b) protease, (c) urease, (d) arylsulfatase, (e) peroxidase. Note: significance is considered at p < 0.05. Full article ">Figure 4
Changes in bacterial (a) and archaeal (b) community composition in different piles at the genus level during the composting process. Full article ">Figure 5
Random forest models (RF) quantifying the contribution of urea coupled with exogenous factors to microbial community structure, networks, and environmental genes. * p < 0.05, ** p < 0.01. Full article ">Figure 6
The structural equation model showed the direct and indirect effects of association of CH4 with cellulases, physicochemical properties, Methanobacterium, and Methanosarcina. The continuous arrow and the dotted arrow indicate positive and negative relationships, respectively. Asterisks denote significant effect (*, p < 0.05; **, p < 0.01; ***, p < 0.001). Full article ">

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