New strategies for evaluating imidacloprid-induced biological consequences targeted to Eisenia fetida species and the corresponding mechanisms of its toxicity

Novel mechanistic insights into Cr(VI) and Cr(III) induced discrepancies of cellular toxicity and oxidative injury events in Eisenia fetida

Chromium (Cr) poses a high ecological risk, however the toxic mechanisms of Cr in different valence states to soil organisms at cellular and molecular levels are not exactly. In this study, the Eisenia fetida coelomocytes and Cu/Zn-superoxide dismutase (Cu/Zn-SOD) were chosen as the target subjects to investigate the effects and mechanisms of cellular toxicity induced by Cr(VI) and Cr(III). Results indicated that Cr(VI) and Cr(III) significantly reduced the coelomocytes viability. The level of reactive oxygen species (ROS) was markedly increased after Cr(VI) exposure, which finally reduced antioxidant defense abilities, and induced lipid peroxidation and cellular membrane damage in earthworm coelomocytes. However, Cr(III) induced lower levels of oxidative stress and cellular damage with respect to Cr(VI). From a molecular perspective, the binding of both Cr(VI) and Cr(III) with Cu/Zn-SOD resulted in protein backbone loosening and reduced β-Sheet content. The Cu/Zn-SOD showed fluorescence enhancement with Cr(III), whereas Cr(VI) had no obvious effect. The activity of Cu/Zn-SOD continued to decrease with the exposure of Cr. Molecular docking indicated that Cr(III) interacted more readily with the active center of Cu/Zn-SOD. Our results illustrate that oxidative stress induced by Cr(VI) and Cr(III) plays an important role in the cytotoxic differences of Eisenia fetida coelomocytes and the binding of Cr with Cu/Zn-SOD can also affect the normal structures and functions of antioxidant defense-associated protein.

Assessment of toxic effects of thallium on the earthworm Eisenia fetida using the biomarker response index

Thallium (Tl), though not essential for biological systems, is widely used in industrial activities, resulting in soil pollution and adverse effects on soil biota. Systematic toxicological studies on Tl, especially concerning soil organisms, are relatively rare. This research evaluates the toxic effects of Tl on earthworms by measuring oxidative stress biomarkers, such as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), malondialdehyde (MDA), and 8-hydroxydeoxyguanosine (8-OHdG), and by assessing the expression of functional genes, such as heat shock protein 70 (Hsp70), metallothionein (MT), and annetocin (ANN). Additionally, this study employs the Biomarker Response Index (BRI) and two-way ANOVA to comprehensively assess the cumulative toxicity of Tl in earthworms. The findings indicate that Tl exposure significantly exacerbates oxidative stress and cellular damage in earthworms, particularly under conditions of high concentration and prolonged exposure. BRI results demonstrate a continuous decline in the physiological state of earthworms with increasing Tl concentration and exposure duration. Two-way ANOVA reveals significant dose-responsive increases in SOD and CAT activities, as well as in ANN gene expression. Apart from GST activity, other biomarkers significantly increased over time, and the changes in biomarkers such as SOD, CAT, MDA, and 8-OHdG were significantly influenced by dose and time. LSD post hoc tests show significant effects of dose, time, and their interactions on all biomarkers except for GST. These findings are valuable for gaining a deeper understanding of the ecological risks of Tl in soil environments and its potential threats to soil biota, aiding in the management of ecological risks associated with Tl-contaminated soils.

Co-exposure of decabromodiphenyl ethane and cadmium increases toxicity to earthworms: Enrichment, oxidative stress, damage and molecular binding mechanisms

The increase of electronic waste worldwide has resulted in the exacerbation of combined decabromodiphenyl ethane (DBDPE) and cadmium (Cd) pollution in soil, posing a serious threat to the safety of soil organisms. However, whether combined exposure increases toxicity remains unclear. Therefore, this study primarily investigated the toxic effects of DBDPE and Cd on earthworms at the individual, tissue, and cellular levels under single and combined exposure. The results showed that the combined exposure significantly increased the enrichment of Cd in earthworms by 50.32-90.42 %. The toxicity to earthworms increased with co-exposure, primarily resulting in enhanced oxidative stress, inhibition of growth and reproduction, intensified intestinal and epidermal damage, and amplified coelomocyte apoptosis. PLS-PM analysis revealed a significant and direct relationship between the accumulation of target pollutants in earthworms and oxidative stress, damage, as well as growth and reproduction of earthworms. Furthermore, IBR analysis indicated that SOD and POD were sensitive biomarkers in earthworms. Molecular docking elucidated that DBDPE and Cd induced oxidative stress responses in earthworms through the alteration of the conformation of the two enzymes. This study enhances understanding of the mechanisms behind the toxicity of combined pollution and provides important insights for assessing e-waste contaminated soils.

Ecotoxicological effects of tungsten on celery (Apium graveolens L) and pepper (Capsicum spp.)

Background

Tungsten (W) is an emerging heavy metal pollutant, yet research remains scarce on the biomonitor and sensitive biomarkers for W contamination.

Methods

In this study, celery and pepper were chosen as study subjects and subjected to exposure cultivation in solutions with five different levels of W. The physiological and biochemical toxicities of W on these two plants were systematically analyzed. The feasibility of utilizing celery and pepper as biomonitor organisms for W contamination was explored and indicative biomarkers were screened.

Results

The results indicated that W could inhibit plants' root length, shoot height, and fresh weight while concurrently promoting membrane lipid peroxidation. Additionally, W enhanced the activities of superoxide dismutase (SOD), catalase (CAT), peroxidase (POD), and total antioxidant capacity (TAOC) to counteract oxidative damage. From a physiological perspective, pepper exhibited potential as a biomonitor for W contamination. Biochemical indicators suggested that SOD could serve as a sensitive biomarker for W in celery, while TAOC and POD were more suitable for the roots and leaves of pepper. In conclusion, our study investigated the toxic effects of W on celery and pepper, contributing to the understanding of W's environmental toxicity. Furthermore, it provided insights for selecting biomonitor organisms and sensitive biomarkers for W contamination.

Molecular mechanisms of polystyrene nanoplastics and alpha-amylase interactions and their binding model: A multidimensional analysis

Plastic fragments are widely distributed in different environmental media and has recently drawn special attention due to its difficulty in degradation and serious health and environmental problems. Among, nanoplastics (NPs) are smaller in size, larger in surface/volume ratio, and more likely to easily adsorb ambient pollutants than macro plastic particles. Moreover, NPs can be easily absorbed by wide variety of organisms and accumulate in multiple tissues/organs and cells, thus posing a more serious threat to living organisms. Alpha-amylase (α-amylase) is a hydrolase, which can be derived from various sources such as animals, plants, and microorganisms. Currently, no studies have concentrated on the binding of NPs with α-amylase and their interaction mechanisms by employing a multidimensional strategy. Hence, we explored the interaction mechanisms of polystyrene nanoplastics (PS-NPs) with α-amylase by means of multispectral analysis, in vitro enzymatic activity analysis, and molecular simulation techniques under in vitro conditions. The findings showed that PS-NPs had the capability to bind with the intrinsic fluorescence chromophores, leading to fluorescence changes of these specific amino acids. This interaction also caused the alterations in the micro-environment of the fluorophore residues mainly tryptophan (TRP) and tyrosine (TYR) residues of α-amylase. PS-NPs interaction promoted the unfolding and partial expansion of polypeptide chains and the loosening of protein skeletons, and destroyed the secondary structure (increased random coil contents and decreased α-helical contents) of this protein, forming a larger particle size of the PS-NPs-α-amylase complex. Moreover, the enzymatic activity of α-amylase in vitro was found to be inhibited in a concentration dependent manner, thereby impairing its physiological functions. Further molecular simulation found that PS-NPs had a higher tendency to bind to the active site of α-amylase, which is the cause for its structural and functional changes. Additionally, the hydrophobic force played a major role in mediating the binding interactions between PS-NPs and α-amylase. Taken together, our study indicated that PS-NPs interaction can initiate the abnormal physiological functions of α-amylase through PS-NPs-induced structural and conformational alternations.

Molecular mechanisms of nano-sized polystyrene plastics induced cytotoxicity and immunotoxicity in Eisenia fetida

Nanoplastics (NPs) are currently everywhere and environmental pollution by NPs is a pressing global problem. Nevertheless, until now, few studies have concentrated on the mechanisms and pathways of cytotoxic effects and immune dysfunction of NPs on soil organisms employing a multidimensional strategy. Hence, earthworm immune cells and immunity protein lysozyme (LZM) were selected as specific receptors to uncover the underlying mechanisms of cytotoxicity, genotoxicity, and immunotoxicity resulting from exposure to polystyrene nanoplastics (PS-NPs), and the binding mechanisms of PS-NPs-LZM interaction. Results on cells indicated that when earthworm immune cells were exposed to high-dose PS-NPs, it caused a notable rise in the release of reactive oxygen species (ROS), resulting in oxidative stress. PS-NPs exposure significantly decreased the cell viability of earthworm immune cells, inducing cytotoxicity through ROS-mediated oxidative stress pathway, and oxidative injury effects, including reduced antioxidant defenses, lipid peroxidation, DNA damage, and protein oxidation. Moreover, PS-NPs stress inhibited the intracellular LZM activity in immune cells, resulting in impaired immune function and immunotoxicity by activating the oxidative stress pathway mediated by ROS. The results from molecular studies revealed that PS-NPs binding destroyed the LZM structure and conformation, including secondary structure changes, protein skeleton unfolding/loosening, fluorescence sensitization, microenvironment changes, and particle size changes. Molecular docking suggested that PS-NPs combined with active center of LZM easier and inhibited the protein function more, and formed a hydrophobic interaction with TRP 62, a crucial amino acid residue closely associated with the function and conformation of LZM. This is also responsible for LZM conformational changes and functional inhibition /inactivation. These results of this research offer a fresh outlook on evaluating the detriment of NPs to the immune function of soil organisms using cellular and molecular strategies.

Regulation mechanisms of ferric ions release from iron-loaded transferrin protein caused by nano-sized polystyrene plastics-induced conformational and structural changes

Currently, the binding of iron-binding protein transferrin (TF) with NPs and their interaction mechanisms have not been completely elucidated yet. Here, we probed the conformation-dependent release of Fe ions from TF induced by nano-sized polystyrene plastics (PS-NPs) using dialysis, ICP-MS, multi-spectroscopic techniques, and computational simulation. The results showed that the release of free Fe ions from TF was activated after PS-NPs binding, which displayed a clear dose-effect correlation. PS-NPs binding can induce the unfolding and loosening of polypeptide chain and backbone of TF. Alongside this we found that the TF secondary structure was destroyed, thereby causing TF protein misfolding and denaturation. In parallel, PS-NPs interacted with the chromophores, resulting in the occurrence of fluorescence sensitization effects and the disruption of the surrounding micro-environment of aromatic amino acids. Also, the binding of PS-NPs induced the formation of new aggregates in the PS-NPs-TF system. Further simulations indicated that PS-NPs exhibited a preference for binding to the hinge region that connects the C-lobe and N-lobe, which is responsible for the Fe ions release and structural alterations of TF. This finding provides a new understanding about the regulation of the release of Fe ions of iron-loaded TF through NPs-induced conformational and structural changes.