La Exposure Research Articles

Association between Exposure of Rare Earth Elements and Outcomes of In Vitro Fertilization-Embryo Transfer in Beijing

Objective The study aimed to investigate the impact of rare earth elements (REEs) exposure on pregnancy outcomes of in vitro fertilization-embryo transfer (IVF-ET) by analyzing samples from spouses.Methods A total of 141 couples were included. Blood and follicular fluid from the wives and semen plasma from the husbands, were analyzed for REEs using inductively coupled plasma mass spectrometry (ICP-MS). Spearman's correlation coefficients and the Mann–Whitney U test were used to assess correlations and compare REE concentrations among three types of samples, respectively. Logistic models were utilized to estimate the individual REE effect on IVF-ET outcomes, while BKMR and WQS models explored the mixture of REE interaction effects on IVF-ET outcomes.Results Higher La concentration in semen (median 0.089 ng/mL, P = 0.03) was associated with a lower fertilization rate. However, this effect was not observed after artificial selection intervention through intracytoplasmic sperm injection (ICSI) (P = 0.27). In semen, the REEs mixture did not exhibit any significant association with clinical pregnancy.Conclusion Our study revealed a potential association between high La exposure in semen and a decline in fertilization rate, but not clinical pregnancy rate. This is the first to report REEs concentrations in follicular fluid with La, Ce, Pr, and Nd found at significantly lower concentrations than in serum, suggesting that these four REEs may not accumulate in the female reproductive system. However, at the current exposure levels, mixed REEs exposure did not exhibit reproductive toxicity.

Appraisal of the Physiological Response of Cakile maritima and Brassica juncea for Tolerating Lanthanum Stress

Rare earth elements were extensively employed for many years to improve plant growth in farming. However, their effect on plant’s behavior relies on their concentration and the plant species. The impact of low doses of lanthanum (La; 1–10 µM) on plant growth, mineral uptake, and the production of secondary metabolites was assessed in two Brassicaceae species (Cakile maritime and Brassica juncea) after 14 days of La exposure. The La accumulation potential was also evaluated. Results showed that both species were able to maintain good dry biomass production under La. C. maritima plants accumulated more La than B. juncea, and a higher accumulation was noticed in the roots (in both plant species). Accordingly to La accumulation in plant tissues, nutrient absorption was affected in C. maritima shoots and roots, whereas no severe effect on nutrient contents was noticed in B. juncea. Phenolic compounds increased in the aerial and underground parts of both species; thus, the accretion was more notorious in shoots of the highest La concentrations. The studied Brassicaceae species showed an ability to survive in a La-contaminated medium. However, according to tolerance index values, C. maritima was found to be more tolerant of La than B. juncea.

Toxic effects of lanthanum(III) on photosynthetic performance of rice seedlings: Combined chlorophyll fluorescence, chloroplast structure and thylakoid membrane protein assessment

Rare earth elements (REEs) are emerging as an anticipated pollution in the environment due to their active use in many areas. However, the effects of REEs on the photosynthesis of rice have not been thoroughly explored. Therefore, this study emphasizes how high levels of La(III) affect the thylakoid membrane of rice seedlings, thereby inhibiting photosynthesis and growth. Here, we reported that rice plants treated with La(III) exhibited an increase in La accumulation in the leaves, accompanied by a decrease in chlorophyll content and photosynthetic capacity. La(III) exposure decreased Mg content in leaves, but possibly increased other nutrients including Cu, Mn, and Zn through systemic endocytosis. K-band and L-band appeared in the fluorescence OJIP transients, indicating La(III) stress destroyed the donor and receptor sides of photosystem II (PSII). Numerous reaction centers (RC/CSm) were inactivated by La(III) treatment, which resulted in a reduction in electron transport capacity (decreased ETo/RC and ETo/CSm) and an increase in the dissipation of the excess excitation energy by heat (increased DIo/RC and DIo/CSm). The BN-PAGE analysis of thylakoid membrane protein complexes showed that La(III) induced the degradation of supercomplexes, PSII core, LHCII, PSI core, LHCI, and F1-ATPase binding Cyt b6f complex. Collectively, this study revealed that La(III) causes significant degradation of thylakoid membrane proteins, thereby promoting the decomposition of photosynthetic complexes, ultimately destroying the chloroplast structure and reducing the photosynthetic performance of rice seedlings.

Two-phase effects of environmentally relevant lanthanum on life-history traits of Daphnia magna and transgenerational bioenergetic profiles: Implications for nutritional and environmental consequences

The versatile applicability of rare earth elements (REEs) especially lanthanum (La) in diverse fields, has led to large-scale mineral exploitation globally, inevitably resulting in substantial release of La into environment. As emerging anthropogenic environmental contaminant, La-induced toxicological effects and potential ecotoxicological implications in relation to realistic levels of La in aquatic ecosystems are becoming major concerns. To address these issues, Daphnia magna was selected as a prototype, and toxicity tests were conducted to explore the effects of La exposure on life-history characteristics and fecundity fitness, as showcased by quantitative variations from the individual level to population scale. In parallel, to further denote transgenerational caloric impacts of parental La exposure, bioenergetic profiles on newborn neonates were concurrently determined by measuring macromolecule forms in terms of proteins, glycogens and lipids to quantify nutritional alterations at progeny level. The results revealed that low-dose La exposure slightly stimulated the demographic potential and nutritional responses, exhibiting dose-dependent hormesis-like effects and promising non-toxicological potential to Daphnia, whereas high-dose La exposure of greater than 59.2 µg La L − 1, conspicuously imposed detrimental effects on quantity and quality of offspring, i.e. not only reducing body size, lifespan expectancy and reproductive output in a concentration-dependent way and resulting in lower population fitness by a dynamic life-table analysis, but eventually leading to the decrease of nutritional qualities and caloric contents on neonates. Taken together, these two-phase findings regarding the dose-related shift from hormesis to inhibition not only provided valuable insights into the complicated biological outcomes of La effects on environmentally-relevant organisms, but experimentally highlighted the significant implications of considering environmental and nutritional consequences in ecologically assessing the La-triggered risk at environmentally realistic occurrences, particularly on gradient scenarios crossing upstream and downstream of highly complex mining watersheds.

Photosynthetic, antioxidative, and metabolic adjustments of a crop plant to elevated levels of La and Ce exposure

Rare earth elements (REEs) have been widely applied as fertilizers in farmland of China for decades to improve the yield and quality of crops. Unfortunately, adverse effects on plants have been observed due to overdosing with REEs. Until now, the toxicology of REEs was mainly evaluated based on phenotypic responses, but knowledge gaps still exist concerning their metabolic effects. Here, the physiological responses and nontargeted metabolomics studies were combined to systematically explore the potential effects of La and Ce on a crop plant, wheat Triticum aestivum. It was observed that REEs accumulated in the shoots of wheat, with significant reduction of the shoot biomass at higher exposure doses. The disturbance of photosynthesis and induced oxidative stress were identified by analyzing indicators of the photosynthetic (chlorophyll a/b, carotenoid and rubisco) and antioxidant systems (POD, CAT, SOD, GSH and MDA). Furthermore, the global metabolic profiles of REEs treatment groups and the non-exposed control group were screened and compared, and the metabolomic disturbance of REEs was dose-dependent. A high overlap of significantly changed metabolites and matched disturbed biological pathways was found between La and Ce treatments, indicating similarity of their toxicity mechanism in wheat shoots. Generally, the perturbed metabolomic pathways were mainly related to carbohydrate, amino acid and nucleotide/side metabolism, suggesting a disturbance of carbon and nitrogen metabolism, which finally affected the growth of wheat. We thus proved the potential adverse effect of inappropriate application of REEs in crop plants and postulated metabolomics as a feasible tool to identify the underlying toxicological mechanisms.

Do climate change related factors modify the response of Mytilus galloprovincialis to lanthanum? The case of temperature rise

Most of the electric and electronic waste is not recycled and the release of its components into the environment is expected, including the rare-earth element Lanthanum (La), which has already been reported in the aquatic systems. Furthermore, considering climate change factors such as the predicted increase in temperature, the susceptibility of aquatic organisms to these rare elements may be modified. In light of this, the present study aimed to evaluate the relevance of temperature on La-derived effects in the mussel Mytilus galloprovincialis. Several biomarkers and La bioaccumulation were assessed in organisms exposed to 0 (control) and 10 μg/L of La at two distinct temperatures (17 and 22 °C) for 28 days. Results showed that temperature did not influence La bioaccumulation in mussels. However, exposure to La resulted in a decreased metabolic capacity and an enhancement of biotransformation enzymes activity, as a possible defense behavior of mussels to avoid La accumulation and toxicity. Nevertheless, antioxidant defenses were also inhibited leading to increased lipid peroxidation (LPO) levels. Warming alone seemed to cause a metabolic shutdown seen as reduced enzyme activities and protein carbonylation (PC) levels. Simultaneous La exposure and temperature rise caused combined effects on mussels, as they accused metabolic depression, biotransformation defenses activation, antioxidant capacity reduction, and higher cellular damage. Overall, this study highlights the need to perform environmental risk assessment studies, by considering emerging contaminants exposures at relevant concentrations, both at present and forecasted climate change scenarios.

Short-Term Toxicity of Lanthanum to Embryonic and Yolk-Sac Stage Larvae of the Rare Minnow Gobiocypris rarus Ye & Fu, 1983

The wide use of rare-earth elements in China for aquacultural purposes and many other applications has resulted in their accumulation in the aquatic environment and has caused concern about their safety. In this study, we tested the toxicity of lanthanum (La (III)) to the early life stages (embryonic and sac-fry stages) of the rare minnow Gobiocypris rarus Ye & Fu, 1983. We exposed fertilized eggs to 0, 0.06, 0.13, 0.25, 0.50, 1.00, and 1.92 mg/L of La (III) until the yolk sac was exhausted in any group (at about 168 h of exposure). Exposure to 1.00 and 1.92 mg/L La (III) had obvious lethal effects on embryos, La (III) exposure also accelerated the development of embryos and had a significant inhibitory effect on the hatching rate after 96 h. As the exposure time increased, the larvae exhibited obvious yolk-sac edema, pericardium edema, spinal curvature, tail bending, and other symptoms of poisoning, including deflated swim-bladder. In general, these results clearly indicate that La pollutants hinder the development of rare minnow embryos and are acutely toxic to rare minnow larvae. Our finding would provide a theoretical basis for further research of relevant feed additive criteria for this fish.

Genome-Wide Mutant Screening in Yeast Reveals that the Cell Wall is a First Shield to Discriminate Light From Heavy Lanthanides.

The rapidly expanding utilization of lanthanides (Ln) for the development of new technologies, green energies, and agriculture has raised concerns regarding their impacts on the environment and human health. The absence of characterization of the underlying cellular and molecular mechanisms regarding their toxicity is a caveat in the apprehension of their environmental impacts. We performed genomic phenotyping and molecular physiology analyses of Saccharomyces cerevisiae mutants exposed to La and Yb to uncover genes and pathways affecting Ln resistance and toxicity. Ln responses strongly differed from well-known transition metal and from common responses mediated by oxidative compounds. Shared response pathways to La and Yb exposure were associated to lipid metabolism, ion homeostasis, vesicular trafficking, and endocytosis, which represents a putative way of entry for Ln. Cell wall organization and related signaling pathways allowed for the discrimination of light and heavy Ln. Mutants in cell wall integrity-related proteins (e.g., Kre1p, Kre6p) or in the activation of secretory pathway and cell wall proteins (e.g., Kex2p, Kex1p) were resistant to Yb but sensitive to La. Exposure of WT yeast to the serine protease inhibitor tosyl phenylalanyl chloromethyl ketone mimicked the phenotype of kex2∆ under Ln, strengthening these results. Our data also suggest that the relative proportions of chitin and phosphomannan could modulate the proportion of functional groups (phosphates and carboxylates) to which La and Yb could differentially bind. Moreover, we showed that kex2∆, kex1∆, kre1∆, and kre6∆ strains were all sensitive to light Ln (La to Eu), while being increasingly resistant to heavier Ln. Finally, shotgun proteomic analyses identified modulated proteins in kex2∆ exposed to Ln, among which several plasmalemma ion transporters that were less abundant and that could play a role in Yb uptake. By combining these different approaches, we unraveled that cell wall components not only act in Ln adsorption but are also active signal effectors allowing cells to differentiate light and heavy Ln. This work paves the way for future investigations to the better understanding of Ln toxicity in higher eukaryotes.

U-Shaped Relationship of Rare Earth Element Lanthanum and Oral Cancer Risk: A Propensity Score-Based Study in the Southeast of China.

As an important rare earth element (REE) extensively applied to industry, agriculture, and medicine, lanthanum (La) has attracted a host of health concerns. This study aimed to explore the relationship between La exposure and the risk of developing oral cancer through a case-control study with a large sample size. Serum La levels of 430 oral cancer patients and 1,118 healthy controls were detected by inductively coupled plasma mass spectrometry (ICP-MS). The association of La level with the risk of oral cancer was assessed in two ways: (1) as a continuous scale based on restricted cubic splines (RCS); (2) as a priori defined centile categories using multivariate logistic regression model, based on propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). The RCS revealed a non-linear U-shaped relationship between serum La and oral cancer risk. Serum La deficiency or excess was associated with an increased risk of oral cancer. When the La level was analyzed as a categorical variable, a similar U-shaped association was observed. Of note, compared to those with La concentrations of 0.243–0.341 μg/L (reference quantiles, 41st−60th), the risk was increased in those with the lower or higher quantiles (0.132–0.242 μg/L vs. 0.243–0.341 μg/L: OR = 1.80, 95%CI: 1.07–3.02; 0.342–0.497 μg/L vs. 0.243–0.341 μg/L: OR = 2.30, 95%CI: 1.38–3.84). The results were generally consistent with the PSM and IPTW analyses. This preliminary study provides strong evidence that there was a U-shaped relationship between serum La levels and oral cancer risk. Much additional work is warranted to confirm our findings.

The Global Regulator CcpA of Listeria monocytogenes Confers Sensitivity to Antimicrobial Fatty Acids.

Free fatty acids (FFAs) are known to exhibit antimicrobial and anti-virulent properties against bacterial pathogens. Specific FFAs, such as lauric acid (LA; C12:0), exert both effects against the foodborne pathogen Listeria monocytogenes: at low levels, LA acts to inhibit the activity of the virulence regulator PrfA, whereas at higher levels, LA inhibits bacterial growth. Deletion of prfA is known to promote tolerance toward antimicrobial FFAs, suggesting that the response of L. monocytogenes to anti-virulent and antimicrobial FFAs could be linked. In this study, we explored the response of L. monocytogenes toward antimicrobial FFAs holding an anti-virulence activity by isolating strains that can grow at high concentrations of LA. We found that LA-tolerant isolates carry mutations in the gene encoding the global regulator CcpA. Importantly, we discovered that mutation or deletion of ccpA protect L. monocytogenes against the antimicrobial activity of FFAs, whereas the ccpA mutants remain sensitive toward FFA’s PrfA inhibitory effect. A regulatory link involving CcpA, connecting the response toward the antimicrobial and anti-virulence activities of FFAs, is therefore unlikely. To further study how deletion of ccpA promotes FFA tolerance, we performed a transcriptomic analysis of the response to LA. Our data indicated that the FFA-tolerant phenotype of the ∆ccpA strain is not induced upon LA exposure but appears to be an inherent phenotypic trait of the ccpA deletion mutation. Interestingly, we found that the bacterial surface of L. monocytogenes becomes more hydrophilic upon deletion of ccpA, and we demonstrate that CcpA plays a role in the response of L. monocytogenes to other stress conditions, including low pH and antibiotics. Altogether, our study revealed that regulatory activities of CcpA lead to an increased hydrophobicity of the bacterial surface, which may confer sensitivity of L. monocytogenes against the antimicrobial activity of FFAs. Notably, CcpA is not involved in responding to the PrfA inhibitory effect of FFAs, showing that FFA-tolerant strains can still be targeted by the anti-virulent activity of FFAs.

Enrichment process of lanthanum as a nonessential trace element in leaf cells of lettuce (Lactuca sativa L.)

Rare earth elements (REEs) as nonessential trace elements are enriched in living organisms and threaten their health. To early detect and reduce REE enrichment in living organisms, scientists are focused on clarifying the enrichment process of REEs in living organisms and its risks. However, the enrichment process of REEs in edible plant cells has remained unclear. Herein, by using interdisciplinary methods and techniques, the enrichment process of lanthanum (La(III)) in the leaf cells of lettuce (Lactuca sativa L.) was investigated. (1) When La(III) exposure dose is 0.5–5 μmol/L, La(III) is enriched outside the plasma membrane (PM). In this zone, La(III) is bound to vitronectin-like protein (VN) to form La–VN complexes; (2) When La(III) exposure dose is 5–20 μmol/L, besides the zone outside the PM, La(III) is also enriched on the PM and bound to arabinogalactan proteins (AGPs) to form La–AGPs complexes; (3) When La(III) exposure dose is 20–140 μmol/L, besides the zone outside and on the PM, La(III) is enriched inside the PM; (4) When La(III) exposure dose is 60–140 μmol/L, malondialdehyde content (an important indicator of invisible damage) significantly increases. Thus, as La(III) exposure dose increases, La(III) gradually migrates from outside the PM to the PM and inside the PM, enriching in these zones in turn. The enriched La(III) will cause invisible damage to lettuce leaf cells and even enter human bodies along food chains. These results provide references for investigating the enrichment process of REEs in plants and its environmental risks, and finding strategies to early detect and reduce REE enrichment in plants.

Phytoextraction and recovery of rare earth elements using willow (Salix spp.)

Soil and water contaminations are caused by rare earth elements (REEs) due to mining and industrial activities, that threaten the ecosystem and human health. Therefore, phytoremediation methods need to be developed to overcome this problem. To date, little research has been conducted concerning the phytoremediation potential of Salix for REEs. In this study, two Salix species (Salix myrsinifolia and Salix schwerinii) and two Salix cultivars (Klara and Karin) were hydroponically exposed to different concentrations of six–REE for 4 weeks. The treatments were: T1 (Control: tap water), T2 (La: 50 mg/L) and T3 (La 11.50 + Y 11 + Nd 10.50 + Dy 10 + Ce 12 and Tb 11.50 in mg L−1). The effects of the REE on Salix growth indicators (height, biomass, shoot diameter and root length), concentrations of REE in the produced biomass, and accumulation of REE in different parts of the Salix (stem, root, and leaf) tissues, were determined. In addition, the retention of REE in ashes following Salix combustion (800 and 1000 °C) was determined. The result indicates that with La and REE exposure, the height growth, dry biomass, shoot diameter and root length of all Salix remained equivalent to the control treatment excluding Klara, which displayed relatively higher growth in all parameters. Further, among the REE studied, the highest La concentration (8404 μg g−1 DW) and La accumulation (10,548 μg plant−1) were observed in Karin and Klara root respectively. Translocations and bioconcentration factors were discovered at <1 for all Salix, which indicates their phytostabilization potential. The total REE concentrations in bottom ashes varied between 7 and 8% with retention rates between 85 and 89%. This study demonstrates that Salix are suitable candidates for REE phytostabilization and the remediation of wastewater sites to limit metals percolating to the water layers in the ecosystem.

Salinity influences on the response of Mytilus galloprovincialis to the rare-earth element lanthanum

The multiplicity and wide variety of applications of electrical and electronic equipment has largely increased with the technological and economic progress and, in consequence, the amount of generated waste of electrical and electronic equipment (WEEE). Due to inappropriate processing and disposal of WEEE, different chemical elements and compounds, including rare-earth elements such as Lanthanum (La) have been released in the environment. Nevertheless, the environmental risks resulting from La presence are almost unknown, especially in marine systems, which may be challenged by foreseen climate changes such as water salinity shifts. Within this context, the present study aimed to understand the combined effects of salinity and La by assessing biochemical alterations in mussels Mytilus galloprovincialis exposed to La (0 and 10 μg/L) at different salinity levels (20, 30 and 40). A decrease in salinity caused a wide range of biochemical changes to both non-contaminated and contaminated organisms, such as metabolism, antioxidant and biotransformation defenses activation, associated to hypotonic stress. Furthermore, the decrease in salinity enhanced the effects of La exposure seen as an increase on lipid and protein cellular damage in those exposed, probably due to free metal ions increase at lower salinities, resulting in a higher bioaccumulation and toxicity. In general, La exposure caused cellular damage and inhibition of antioxidant defenses in contaminated mussels when compared to non-contaminated ones, with cellular damages being higher at the lowest salinity. Overall, the present study highlights the need to investigate the presence and impacts of emerging contaminants of WEEE source at environmental relevant concentrations, not just at present but also under forecasted climate change scenarios, thus providing a more realistic environmental risk assessment.

The effect of four lanthanides onto a rat kidney cell line (NRK-52E) is dependent on the composition of the cell culture medium

Lanthanide (Ln) exposure poses a serious health risk to animals and humans. In this study, we investigated the effect of 10−9–10−3 M La, Ce, Eu, and Yb exposure onto the viability of rat renal NRK-52E cells in dependence on Ln concentration, exposure time, and composition of the cell culture medium. Especially, the influence of fetal bovine serum (FBS) and citrate onto Ln cytotoxicity, solubility, and speciation was investigated. For this, in vitro cell viability studies using the XTT assay and fluorescence microscopic investigations were combined with solubility and speciation studies using TRLFS and ICP-MS, respectively. The theoretical Ln speciation was predicted using thermodynamic modeling.All Ln exhibit a concentration- and time-dependent effect on NRK-52E cells. FBS is the key parameter influencing both Ln solubility and cytotoxicity. We demonstrate that FBS is able to bind Ln3+ ions, thus, promoting solubility and reducing cytotoxicity after Ln exposure for 24 and 48 h. In contrast, citrate addition to the cell culture medium has no significant effect on Ln solubility and speciation nor cytotoxicity after Ln exposure for 24 and 48 h. However, a striking increase of cell viability is observable after Ln exposure for 8 h. Out of the four Ln elements under investigation, Ce is the most effective.Results from TRLFS and solubility measurements correlate well to those from in vitro cell culture experiments. In contrast, results from thermodynamic modeling do not correlate to TRLFS results, hence, demonstrating that big gaps in the database render this method, currently, inapplicable for the prediction of Ln speciation in cell culture media. Finally, this study demonstrates the importance and the synergistic effects of combining chemical and spectroscopic methods with cell culture techniques and biological methods.

Action of Akt Pathway on La-Induced Hippocampal Neuron Apoptosis of Rats in the Growth Stage.

This study investigated the influences of lanthanum (La) exposure on learning and memory and the expression of apoptosis-related proteins in offspring rats. Wistar female rats were randomly divided into a control group (NC) and 0.25%, 0.5% and 1.0% LaCl3 treatment groups, with eight per group. La dye was transmitted to offspring rats through parental blood circulation and breast milk before delactation and through water drinking after delectation. Offspring rats were killed at 14, 28 and 42days after birth. Hippocampal neurons were observed by microscope, and apoptosis and necrosis were tested. The expression levels of apoptosis-related proteins were detected by Western blot, and Morris water maze experiments were used to measure learning and memory abilities. LaCl3 groups showed longer escape latency periods and swimming distances than the NC group (p < 0.05). The 1.0% LaCl3 group passed across the target quadrants and platforms more times and stayed in the target quadrants for less time, than the NC group (p < 0.05). At 42days, the apoptosis rate and necrosis in the hippocampus of the 1.0% LaCl3 group were significantly higher than those of other groups. There was a significant difference among LaCl3 groups in terms of protein expressions measured in the hippocampus. In LaCl3 groups, caspase-3 and caspase-9 were significantly higher than in the NC group (p < 0.05). Therefore, La exposure can promote neuronal apoptosis by regulating the protein expressions of Akt, Bcl-2, Bcl-xl, Bax, Bad, caspase-3 and caspase-9, thus damaging learning and memory and the hippocampal neurons of offspring rats.

Lanthanum Chloride Causes Neurotoxicity in Rats by Upregulating miR-124 Expression and Targeting PIK3CA to Regulate the PI3K/Akt Signaling Pathway

Background Lanthanum (La) exposure can cause central nervous system (CNS) damage and dysfunction in children, seriously affecting intellectual development. miR-124 plays an important role in the development of the nervous system. We exposed rats to a La environment then observed the rats' learning and memory damage and neurotoxicity and the relationship with miR-124. Methods Rats were exposed to LaCl3 via drinking water. The rats' offspring were exposed to LaCl3 from their mother before weaning, then from La water for 28 days. A Morris water maze was used to observe spatial memory capabilities. H&E staining and TUNEL assays were used to observe pathological changes and apoptosis in the hippocampus. miR-124 was detected by RT-qPCR, and its targeting was confirmed by luciferase assay. The HT22 cell line was cultured with LaCl3 and treated with miR-124 mimics or inhibitors; then, expression of PI3K/Akt-related proteins was detected by western blot. Results La exposure can lead to impaired learning and memory ability in offspring. Offspring with La accumulations in the hippocampus showed severe damage, disordered cells, and increased neurocyte apoptosis. In vitro, the postsynaptic density protein 95 was downregulated under La exposure and apoptosis increased. This effect of La can be attenuated by miR-124 inhibitors and enhanced by miR-124 mimics. LaCl3 exposure increased miR-124 expression and targeting on PIK3CA, downregulating PI3K, p-Akt, and p-NF-κB p65. Conclusion La causes neurotoxicity by upregulating miR-124 expression and targeting PIK3CA through the PI3K/Akt signaling pathway.

Rare earth elements exposure and the alteration of the hormones in the hypothalamic-pituitary-thyroid (HPT) axis of the residents in an e-waste site: A cross-sectional study

Rare earth elements (REEs) are widely used in electronic products. But the contaminations of REEs in the e-waste sites and the related health effects were barely investigated. In the present study, we analyzed the concentrations of REEs and the hormones of the HPT axis in plasma of subjects recruited from an e-waste area and a reference area in Taizhou, China. The results showed that the concentrations of several REEs like La, Ce were much higher in the exposed group than in the control group (all p < 0.001). The thyroid hormones, FT3 and FT4, and TRH showed no significant difference between the two groups, while the concentration of TSH was significantly higher in the exposed group when compared to the control group (p = 0.002). Separate regression analysis indicated that elevated La and Ce levels were associated with higher TSH concentrations. MDA and 8-iso, the biomarkers of oxidative stress, were also significantly higher in the exposed group than that of the control group (p = 0.002 and p = 0.003, respectively). The increased oxidative stress might be the mechanism underlying the disruptive effects of REEs on TSH. Our results indicated that the quantities of internal exposure of REEs in the subjects in the e-waste area were considerable and the compositional profile of the REEs in the exposed group was different from the control group due to the e-waste dismantling. The expression of TSH were also affected by high La and Ce exposure which showed an endocrine disruption effects of REEs on HPT axis.

Effects of exogenous lanthanum(III) exposure on the positive interaction between mutually beneficial populations.

Rare earth elements (REEs) are widely used in various fields, and their accumulation has been reported to pose environmental risks. Most studies confirmed the damage of excessive REE exposure to individual plants; however, little attention has been given to their effects on plant populations. A positive interaction indicates a mutually beneficial relationship between two populations, which is beneficial to the survival and growth of the populations. However, it remains unknown whether exogenous REEs affect the positive interactions between populations. This study investigated the effects of exogenous lanthanum(III) [La(III)] exposure on the positive interaction between soybean (Glycine max L.) and wheat (Triticum aestivum L.) populations by their modules. At normal nutrient level (½-strength Hoagland), the inhibition of excessive La(III) on population modules decreased with increasing population density. Decreases of 39.26 to 1.05% for soybean and 41.45 to 2.41% for wheat indicated the inhibition of La(III) on the positive interaction of both populations weakened with increasing population density. At low nutrient level (¼-strength Hoagland), the inhibition of excessive La(III) on population modules increased with increasing population density. Decreases of 5.82-57.14% for soybean and 4.22-59.04% for wheat indicated the inhibition of La(III) on the positive interaction of both population was strengthened with increasing population density. In summary, the inhibitory effects of exogenous La(III) exposure on the positive interaction between populations vary with both nutrient level and population density. This is a new factor that needs to be considered when evaluating the safety risks of REEs in the environment.

Ecotoxicological effects of lanthanum in Mytilus galloprovincialis: Biochemical and histopathological impacts

Inappropriate processing and disposal of electronic waste contributes to the contamination of aquatic systems by various types of pollutants such as the rare-earth elements (REE) in which lanthanum (La) is included. Knowledge on the toxicity of these elements in marine organisms is still scarce when compared to other metals such as mercury (Hg) and arsenic (As). Therefore, this study aims to assess the toxicity of La on the mussel Mytilus galloprovincialis, considered a good bioindicator of aquatic pollution, through the analysis of metabolic, oxidative stress, neurotoxicity and histopathological markers. Organisms were exposed to different concentrations of La for a period of 28 days (0, 0.1, 1, 10 mg/L) under controlled temperature (18 °C ± 1.0) and salinity (30 ± 1) conditions. La concentrations in mussels increased in higher exposure concentrations. La exposure demonstrated a biochemical response in mussels, evidenced by lowered metabolism and accumulation of energy reserves, activation of the antioxidant defences SOD and GPx as well as the biotransformation enzymes GSTs, especially at intermediate concentrations. Despite oxidative stress being shown by a decrease in GSH/GSSG, oxidative damage was avoided as evidenced by lower LPO and PC levels. Inhibition of the enzyme AChE demonstrated the neurotoxicity of La in this species. Histopathological indices were significantly different from the control group, indicating impacts in gonads, gills and digestive glands of mussels due to La. These results show that La can be considered a risk for marine organisms and thus its discharge into the environment should be monitored.

Effect of four lanthanides onto the viability of two mammalian kidney cell lines

Exposure to lanthanides (Ln) poses a serious health risk to animals and humans. Since Ln are mainly excreted with urine, we investigated the effect of La, Ce, Eu, and Yb exposure on renal rat NRK-52E and human HEK-293 cells for 8, 24, and 48 h in vitro. Cell viability studies using the XTT assay and microscopic investigations were combined with solubility and speciation studies using ICP-MS and TRLFS. Thermodynamic modeling was applied to predict the speciation of Ln in the cell culture medium.All Ln show a concentration- and time-dependent effect on both cell lines with Ce being the most potent element. In cell culture medium, the Ln are completely soluble and most probably complexed with proteins from fetal bovine serum.The results of this study underline the importance of combining biological, chemical, and spectroscopic methods in studying the effect of Ln on cells in vitro and may contribute to the improvement of the current risk assessment for Ln in the human body. Furthermore, they demonstrate that Ln seem to have no effect on renal cells in vitro at environmental trace concentrations. Nevertheless, especially Ce has the potential for harmful effects at elevated concentrations observed in mining and industrial areas.