Multi-and transgenerational synergistic effects of glyphosate and chlorpyrifos at environmentally relevant concentrations in the estuarine rotifer Proales similis

Toxicity of binary-metal mixtures (As, Cd, Cu, Fe, Hg, Pb and Zn) in the euryhaline rotifer Proales similis: Antagonistic and synergistic effects

Data regarding the effects of binary metal mixtures in marine zooplankton are scarce, particularly for rotifers. We examined the toxicity of 21 binary equitoxic mixtures of As, Cd, Cu, Fe, Hg, Pb, and Zn on the euryhaline rotifer Proales similis. The toxic units (TU50) revealed that 20 of these binary mixtures exhibited synergistic effects (TU50 < 1.00). The AsHg mixture showed a strong antagonistic effect (TU50 = 2.39), whereas the HgCu interaction exhibited a significant synergistic effect (TU50 = 0.29) on P. similis. TU50 values were <0.60 in all cases that showed synergism (80 %). Regarding the MIXTOX analysis, 13 binary mixtures presented some level of synergism, while two mixtures presented only additivity. Results emphasize the need for environmental agencies to revise and readjust protection guidelines for marine biota in response to the evident synergistic effects occurring at metal mixtures concentrations below the current permissible limits.

The situation of chlorpyrifos in Mexico: a case study in environmental samples and aquatic organisms

Chlorpyrifos (CPF) is one of the most commonly used organophosphate pesticides. Because CPF was described as a toxic compound without safe levels of exposure for children, certain countries in Latin America and the European Union have banned or restricted its use; however, in Mexico it is used very frequently. The aim of this study was to describe the current situation of CPF in Mexico, as well as its use, commercialization, and presence in soil, water, and aquatic organisms in an agricultural region of Mexico. Structured questionnaires were applied to pesticide retailers to determine the sales pattern of CPF (ethyl and methyl); in addition, monthly censuses were conducted with empty pesticide containers to assess the CPF pattern of use. Furthermore, samples of soil (48 samples), water (51 samples), and fish (31 samples) were collected, which were analyzed chromatographically. Descriptive statistics were performed. The results indicate that CPF was one of the most sold (3.82%) and employed OP (14.74%) during 2021. Only one soil sample was found above the CPF limit of quantification (LOQ); in contrast, all water samples had CPF levels above the LOQ (x̄ = 4614.2 ng/L of CPF). In the case of fish samples, 6.45% demonstrated the presence of methyl-CPF. In conclusion, the information obtained in this study indicates the need for constant monitoring in the area, since the presence of CPF in soil, water, and fish constitutes a threat to the health of wildlife and humans. Therefore, CPF should be banned in Mexico to avoid a serious neurocognitive health problem.

Environmental toxin chlorpyrifos induces liver injury by activating P53-mediated ferroptosis via GSDMD-mtROS

AIM

We investigate the mechanism whereby chlorpyrifos (CHI), an environmental toxin, causes liver injury by inducing ferroptosis in hepatocytes.

METHODS

The toxic dose (LD50 = 50 μM) of CHI for inducing AML12 injury in normal mouse hepatocytes was determined, and the ferroptosis-related indices were measured, including the levels of SOD, MDA and GSH-Px, as well as the cellular content of iron ions. JC-1 and DCFH-DA assays were employed to detect the mtROS levels, the levels of mitochondrial proteins (GSDMD, NT-GSDMD), as well as the cellular levels of ferroptosis-related proteins (P53, GPX4, MDM2, SLC7A11). We knocked out the GSDMD and P53 in AML12 and observed the CHI-induced ferroptosis of ALM12 after applying YGC063, an ROS inhibitor. In animal experiments, we explored the effect of CHI on liver injury by using conditional GSDMD-knockout mice (C57BL/6 N-GSDMD^em1(flox)Cya) and ferroptosis inhibitor Fer-1. Small molecule-protein docking and Pull-down assay were employed to verify the association between CHI and GSDMD.

RESULTS

We found that CHI could induce ferroptosis of AML12. CHI promoted the cleavage of GSDMD, leading to upregulation of mitochondrial NT-GSDMD expression, as well as ROS levels. P53 activation promoted the ferroptosis. Knock out of GSDMD and P53 could inhibit the CHI-induced ferroptosis, and YGC063 could also inhibit ferroptosis. In mice experiments, GSDMD knockout or Fer-1 intervention could significantly inhibit the CHI-induced liver injury. CHI promoted the cleavage of GSDMD by binding to its SER234 site.

CONCLUSION

CHI can bind to GSDMD to promote its cleavage, while NT-GSDMD can open mitochondrial membrane to promote the mtROS release. Cytoplasmic upregulation of ROS levels can facilitate the P53-mediated ferroptosis. GSDMD-mtROS is the primary mechanism whereby CHI induces ferroptosis in hepatocytes.

Chlorpyrifos-induced dysregulation of synaptic plasticity in rat hippocampal neurons

Chlorpyrifos (CPF) is a widely used organophosphorus pesticide. Increasing evidence has shown that exposure to CPF in early life might induce neurodevelopmental disorders, but the pathogenesis remains uncertain. Synaptic plasticity plays a crucial role in neurodevelopment. This study aimed to investigate the effect of CPF on synaptic plasticity in hippocampal neurons and establish the cellular mechanism underlying these effects. Using CPF-exposed rat and primary hippocampal neurons model, we analyzed the impact of CPF on the synaptic morphology, the expression level of a presynaptic protein, a postsynaptic protein and ionotropic glutamate receptors (iGluRs), as well as the effects on the Wnt/β-catenin pathway. We found that the synapses were shortened, the spines were decreased, and the expression of synaptophysin (Syp), postsynaptic density-95 (PSD-95), GluN1, GluA1 and Wnt7a, as well as active β-catenin in primary hippocampal neurons was decreased. Our study suggests that CPF exposure induced dysregulation of synaptic plasticity in rat hippocampal neurons, which might provide novel information regarding the mechanism of CPF-induced neurodevelopmental disorders.