Fluoride exposure disrupts the cytoskeletal arrangement and ATP synthesis of HT-22 cell by activating the RhoA/ROCK signaling pathway.

BACKGROUND: Fluoride, an environmental contaminant, is ubiquitously present in air, water, and soil. It usually enters the body through drinking water and may cause structural and functional disorders in the central nervous system in humans and animals. Fluoride exposure affects cytoskeleton and neural function, but the mechanism is not clear. METHODS: The specific neurotoxic mechanism of fluoride was explored in HT-22 cells. Cellular proliferation and toxicity detection were investigated by CCK-8, CCK-F, and cytotoxicity detection kits. The development morphology of HT-22 cells was observed under a light microscope. Cell membrane permeability and neurotransmitter content were determined using lactate dehydrogenase (LDH) and glutamate content determination kits, respectively. The ultrastructural changes were detected by transmission electron microscopy, and actin homeostasis was observed by laser confocal microscopy. ATP enzyme and ATP activity were determined using the ATP content kit and ultramicro-total ATP enzyme content kit, respectively. The expression levels of GLUT1 and 3 were assessed by Western Blot assays and qRT-PCR. RESULTS: Our results showed that fluoride reduced the proliferation and survival rates of HT-22 cells. Cytomorphology showed that dendritic spines became shorter, cellular bodies became rounder, and adhesion decreased gradually after fluoride exposure. LDH results showed that fluoride exposure increased the membrane permeability of HT-22 cells. Transmission electron microscopy results showed that fluoride caused cells to swell, microvilli content decreased, cellular membrane integrity was damaged, chromatin was sparse, mitochondria ridge gap became wide, and microfilament and microtubule density decreased. Western Blot and qRT-PCR analyses showed that RhoA/ROCK/LIMK/Cofilin signaling pathway was activated by fluoride. F-actin/G-actin fluorescence intensity ratio remarkably increased in 0.125 and 0.5 mM NaF, and the mRNA expression of MAP2 was significantly decreased. Further studies showed that GLUT3 significantly increased in all fluoride groups, while GLUT1 decreased (p < 0.05). ATP contents remarkably increased, and ATP enzyme activity substantially decreased after NaF treatment with the control. CONCLUSION: Fluoride activates the RhoA/ROCK/LIMK/Cofilin signaling pathway, impairs the ultrastructure, and depresses the connection of synapses in HT-22 cells. Moreover, fluoride exposure affects the expression of glucose transporters (GLUT1 and 3) and ATP synthesis. Sum up fluoride exposure disrupts actin homeostasis, ultimately affecting structure, and function in HT-22 cells. These findings support our previous hypothesis and provide a new perspective on the neurotoxic mechanism of fluorosis.

Performance evaluation of rhamnolipids addition for the biodegradation and bioutilization of petroleum pollutants during the composting of organic wastes with waste heavy oil.

Environmental pollution caused by petroleum hydrocarbons is being paid more and more attention worldwide. Surfactants are able to improve the solubility of petroleum hydrocarbons, but their effects on petroleum hydrocarbon degradation in composting systems are still unclear. In this study, the effects on microbial community succession were investigated by adding petroleum hydrocarbons and rhamnolipids during composting of organic wastes. The results showed that the compost and the addition of rhamnolipids could effectively reduce the petroleum hydrocarbon content with an efficiency of 73.52%, compared to 53.81% for the treatment without addition. Network analyses and Structural Equation Model suggested that there were multiple potential petroleum degraders microbes that might be regulated by nitrogen. The findings in this study can also provide an implication for the treatment of petroleum hydrocarbon pollutants from oil-polluted soil, and the technology can be potentially applied on an industrial scale in practice.

Bisphenol A induces apoptosis in response to DNA damage through c-Abl/YAPY357/ p73 pathway in P19 embryonal carcinoma stem cells.

Bisphenol A (2,2-bis(4'-hydroxyphenyl) propane, BPA) is a well-known endocrine-disrupting compound that is widely used in various daily products and exhibits embryonic development toxicity and genotoxicity. However, the affected signaling pathways involved in embryonic development especially the interactions of involved proteins remain unclear. In our previous study (Ge et al., 2021), BPA induces DNA damage and apoptosis in Xenopus embryos, resulting in multiple malformations of larvae. However, the signaling pathways induced for apoptosis response to DNA damage are still not well elucidated. Here, we systematically elucidated the enriched pathways affected by BPA and illustrated the interactions of involved proteins. Results indicated that BPA affected multiple embryonic development pathways including Hippo, TGF-ß, Wnt, and Notch pathways. Furthermore, the protein-protein interaction network suggested that the c-Abl/YAPY357/p73 pathway may play a key role in apoptosis induction in response to DNA damage. P19 embryonal carcinoma stem cells, as a developmental toxicity model, were treated with different BPA concentrations to establish an in vitro model to verify the role of the c-Abl/YAPY357/p73 pathway in apoptosis. BPA triggered DNA damage and significantly upregulated the expression levels of c-Abl, phosphorylated YAPY357, phosphorylated p73Y99, and cleaved caspase-3 protein (p < 0.05), thus decreasing cell viability and transcriptionally activating the p73 target genes Bax and Puma. These data suggested that BPA activated the c-Abl/YAPY357/p73 pathway in response to DNA damage. Imatinib, an inhibitor of tyrosine kinase c-Abl, significantly downregulated the elevated expression levels of p-YAPY357, p-p73Y99 and cleaved caspase-3 (p < 0.05) caused by BPA and then ameliorated the cell index of P19 cells in the BPA-treated group. Therefore, this substance restrained the phosphokinase activity of c-Abl and suppressed the c-Abl/YAPY357/p73 pathway. Results showed that the c-Abl/YAPY357/p73 pathway served as a mechanism for caspase-3 activation that induced the apoptosis response to DNA damage stress.

Combined effects of 17ß-estradiol and copper on growth, biochemical characteristics and pollutant removals of freshwater microalgae Scenedesmus dimorphus.

Contamination by estrogens and heavy metals can cause great environment concern and necessitate efficient approaches for their removals. In this study, the combined effects of 17ß-estradiol (E2) and Cu(II) on microalgae growth and biochemical characteristics were investigated. Results showed that 1 mg/L Cu(II) promoted the growth of Scenedesmus dimorphus, while 2 mg/L Cu(II) exhibited growth inhibition, compared with the same concentration of E2. Biochemical characteristics including enzyme activities as well as the contents of chlorophyll, protein and carbohydrate were significantly affected by the coexistence of E2 and Cu(II) after 12 d of cultivation. S. dimorphus exhibited high E2 and Cu(II) removal efficiencies (89.9% of E2 and 76.6% Cu(II) under the coexistence of 0.5 mg/L E2 and 1 mg/L Cu(II), respectively). Lower concentration of Cu(II) might serve as a bridge during E2 removal by S. dimorphus while competitive adsorption of Cu(II) and E2 occurred under the condition of excessive Cu(II). Results could confirm that S. dimorphus was a potential bioresource for the effective removal of E2 and Cu(II).

Growth and cardiovascular development are repressed by florfenicol exposure in early chicken embryos.

Florfenicol (FLO) is one of the most popular antibacterial drugs used in veterinary clinics and aquaculture. The drug was found to decrease the hatchability of eggs laid by treated hens in veterinary clinics and research work. However, the pathological changes in developing embryos and their cardiovascular system and the mechanism underlying FLO-induced embryonic death remain unclear. In the present study, fertilized eggs laid by hens treated with a therapeutic dose of FLO were collected and incubated. Results showed that FLO exposure repressed embryonic development and induced early embryonic death. As a result, FLO decreased the hatchability and increased the proportion of weak chicks. Moreover, FLO exposure led to embryonic lethality and inhibited the development of chick embryos as characterized by decreased weights, lagging distribution of Hamburger-Hamilton stages, and dysplastic eyes. Pathological examination indicated that FLO exposure affected the normal development of the heart in 4.5-day-old chick embryos, as characterized by shorter transverse cardiac diameter, disordered arrangement of trabecular muscles in ventricles, and reduced thickness of ventricular walls. Furthermore, FLO decreased blood vascular densities and downregulated the expression levels of key angiogenesis-related genes, including the vascular endothelial growth factor and fibroblast growth factor, in the yolk sac membrane. These findings indicated that FLO exposure restricted vascular development during early embryonic development. In summary, our data suggest that the restricted growth and abnormal cardiovascular development may be responsible for FLO-induced early embryonic death. Thus, these findings can be useful for guiding the proper use of FLO and in laying a foundation for further studies on the mechanism of FLO-induced embryonic toxicity.

Adsorption of 17ß-estradiol from aqueous solution by raw and direct/pre/post-KOH treated lotus seedpod biochar.

Five biochars derived from lotus seedpod (LSP) were applied to examine and compare the adsorption capacity of 17ß-estradiol (E2) from aqueous solution. The effect of KOH activation and the order of activation steps on material properties were discussed. The effect of contact time, initial concentration, pH, ionic strength and humic acid on E2 adsorption were investigated in a batch adsorption process. Experimental results demonstrated that the pseudo second-order model fitted the experimental data best and that adsorption equilibrium was reached within 20 hr. The efficiency of E2 removal increased with increasing E2 concentration and decreased with the increase of ionic strength. E2 adsorption on LSP-derived biochar (BCs) was influenced little by humic acid, and slightly affected by the solution pH when its value ranged from 4.0 to 9.0, but considerably affected at pH 10.0. Low environmental temperature is favorable for E2 adsorption. Chemisorption, π-π interactions, monolayer adsorption and electrostatic interaction are the possible adsorption mechanisms. Comparative studies indicated that KOH activation and the order of activation steps had significant impacts on the material. Post-treated biochar exhibited better adsorption capacity for E2 than direct treated, pre-treated, and raw LSP biochar. Pyrolyzed biochar at higher temperature improved E2 removal. The excellent performance of BCs in removing E2 suggested that BCs have potential in E2 treatment and that the biochar directly treated by KOH would be a good choice for the treatment of E2 in aqueous solution, with its advantages of good efficiency and simple technology.

Cadmium induces actin cytoskeleton alterations and dysfunction in Neuro-2a cells.

Cadmium (Cd) is considered a possible etiological factor in neurodegenerative diseases. However, the exact mechanism by which Cd induces neurotoxicity is not well elucidated. In this study, Neuro-2a cells were treated with 0, 10, 20, and 40 µM cadmium chloride for 24 hours to investigate the effects of Cd on the cytoskeleton of nerve cells. MTT assay and ELISA assay were used to examine cell viability and release of lactate dehydrogenase (LDH) from cells, respectively. Results showed that Cd reduced cell viability and increased the release of LDH in a dose-dependent manner (P < 0.05). The morphology of treated cell was damaged as indicated by cell collapse and dimensionality reduction. Moreover, the axonal spines and normal features of Cd-treated neurons disappeared. We checked the ultrastructure of Neuro-2a cells and found that Cd-induced swelling, membrane damage, overflow of cytoplasm contents, and cell fragmentation. Damaged mitochondria, expanded endoplasmic reticulum, and abnormal microfilaments were found in Cd-treated cells rather than in untreated cells. Compared with the control group, the relative release of glutamate in the supernatant after Cd treatment was reduced, indicating that Cd exposure could reduce the release of glutamate by inhibiting the function of nerve-2a cells. Cd decreased the mRNA and protein expression levels of cytoskeletal proteins including DBN, SYP, and TAU, which might promote cytoskeleton alterations in Cd-treated cells. In conclusion, Cd-induced actin cytoskeleton alterations and dysfunction of cultured neurons. The results of the present study provide new insights for the investigation of Cd-induced neurotoxicity.

Fabrication of Stabilized Fe⁻Mn Binary Oxide Nanoparticles: Effective Adsorption of 17ß-Estradiol and Influencing Factors.

Fe⁻Mn binary oxide nanoparticles (FMBON) were reported to be high performance as adsorbent for pollutants removal from aqueous solution. However, there are still limitations in practice application due to the FMBON tend to aggregate into the micro millimeter level. In order to avoid the agglomeration of nanoparticles, this work synthesized the stabilized Fe⁻Mn binary oxide nanoparticles (CMC-FMBON) by using water-soluble carboxymethyl celluloses (CMC) as the stabilizer. The characteristics of CMC-FMBON and FMBON were measured by using Transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, and Zeta potential. This work systematically investigated the adsorption capacity of CMC-FMBON for 17ß-estradiol (E2) and the influences of external environmental factors on E2 removal. The results indicated that CMC-FMBON had much smaller particles, wider dispersion and larger surface area than the FMBON. CMC-FMBON showed better adsorption performance for E2 than FMBON with the maximum adsorption capacity of CMC-FMBON and FMBON were 124.10 and 98.14 mg/g at 298 K, respectively. The experimental data can be well fitted by the model of pseudo-second-order and Langmuir model. The E2 removal by CMC-FMBON was obviously dependent on pH with the maximum adsorption occurring when the pH was acidic. The removal capacity of CMC-FMBON increased when enhancing ionic strength in solution. Background electrolytes promoted slightly E2 adsorption process whereas the presence of humic acid inhibited the E2 removal. π-π interactions, hydrogen bonds, and oxidation might be responsible for E2 removal. This research suggested that the CMC-FMBON has been considered to be a cost-efficient adsorbent for removing E2 from water.

Lead-induced changes of cytoskeletal protein is involved in the pathological basis in mice brain.

Lead poisoning is a geochemical disease. On the other hand, lead is highly carcinogenic and exhibits liver and kidney toxicity. This element can also cross the blood-brain barrier, reduce learning and memory ability and damage the structure of the cerebral cortex and hippocampus. To further investigate the mechanism of lead neurotoxicity, 4-week-old Kunming mice were used to explore the effects of different concentrations of Pb2+ (0, 2.4, 4.8 and 9.6 mM) for 9 days. In this study, pathological and ultrastructural changes in brain cells of the treated group were related to damages to mitochondria, chromatin and the nucleus. Lead content in blood was tested by atomic absorption spectroscopy, which showed high lead concentrations in the blood with increasing doses of lead. Distribution of lead in nerve cells was analysed by transmission electron microscopy with energy dispersive spectroscopy. Data showed the presence of lead in nucleopores, chromatin and nuclear membrane of nerve cells in the treatment groups, whereas lead content increased with increasing doses of lead acetate. Finally, microtubule-associated protein 2 (MAP2) mRNA and protein expression levels were detected by real-time PCR and Western blotting, which showed a reduction in MAP2 expression with increasing lead doses in the mouse brain. These findings suggest that acute lead poisoning can cause significant dose-dependent toxic effects on mouse brain function and can contribute to better understanding of lead-induced toxicity.

Adsorption Removal of 17ß-Estradiol from Water by Rice Straw-Derived Biochar with Special Attention to Pyrolysis Temperature and Background Chemistry.

Rice straw biochar that produced at three pyrolysis temperatures (400, 500 and 600 °C) were used to investigate the adsorption properties of 17ß-estradiol (E2). The biochar samples were characterized by scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), elemental analysis and BET surface area measurements. The influences of pyrolysis temperature, E2 concentration, pH, ionic strength, background electrolyte and humic acid were studied. Kinetic and isotherm results illustrated that the adsorption process could be well described by pseudo-second-order and Freundlich models. Experimental results showed that ionic strength had less influence on the adsorption of E2 by 500 and 600 °C rice straw biochar. Further, multivalent ions had positive impact on E2 removal than monovalent ions and the influence of the pyrolysis temperature was unremarkable when background electrolyte existed in solutions. The adsorption capacity of E2 decreased with the pH ranged from 3.0 to 12.0 and the humic acid concentration from 2 to 10 mg L-1. Electrostatic attractions and π-π interaction were involved in the adsorption mechanisms. Compared to low-temperature biochar, high-temperature biochar exhibited a better adsorption capacity for E2 in aqueous solution, indicated it had a greater potential for E2 pollution control.