The Effects of Different Soil Component Couplings on the Methylation and Bioavailability of Mercury in Soil.

Soil composition can influence the chemical forms and bioavailability of soil mercury (Hg). However, previous studies have predominantly focused on the influence of individual components on the biogeochemical behavior of soil Hg, while the influence of various component interactions among several individual factors remain unclear. In this study, artificial soil was prepared by precisely regulating its components, and a controlled potted experiment was conducted to investigate the influence of various organic and inorganic constituents, as well as different soil textures resulting from their coupling, on soil Hg methylation and its bioavailability. Our findings show that inorganic components in the soils primarily exhibit adsorption and fixation effects on Hg, thereby reducing the accumulation of total mercury (THg) and methylmercury (MeHg) in plants. It is noteworthy that iron sulfide simultaneously resulted in an increase in soil MeHg concentration (277%). Concentrations of THg and MeHg in soil with peat were lower in rice but greater in spinach. A correlation analysis indicated that the size of soil particles was a crucial factor affecting the accumulation of Hg in plants. Consequently, even though fulvic acid activated soil Hg, it significantly increased the proportion of soil particles smaller than 100.8 µm, thus inhibiting the accumulation of Hg in plants, particularly reducing the concentration of THg (93%) and MeHg (85%) in water spinach. These results demonstrate that the interaction of organic and inorganic components can influence the biogeochemical behavior of soil Hg not only through their chemical properties, but also by altering the soil texture.

Mercury and methylmercury in Hg-contaminated paddy soil and their uptake in rice as regulated by DOM from different agricultural sources.

In this study, from the perspectives of structural and compositional variations of soil-dissolved organic matter (DOM), we explored the effects of agricultural DOM inputs on methylmercury (MeHg) accumulation in the soil and mercury (Hg) bioaccumulation in rice grains. Pot experiments with the addition of DOMs from maize straw (MaS), rape straw (RaS), rice straw (RiS), composted rice straw (CRiS), cow dung (CD), and composted cow dung (CCD) were then conducted. Results showed that, relative to the control, the DOM amendment from each agricultural source elevated MeHg concentrations in the soil, with an increase of 18-227%, but only parts of DOMs elevated total dissolved Hg (DHg) and MeHg (DMeHg) concentrations in pore water. Among all DOM species, RiS, CRiS, and CCD significantly increased total Hg (THg) and MeHg contents in rice grains by 34-64% and 32-118%, respectively. Compared with RiS, THg and MeHg contents in rice grains in the CRiS treatment decreased slightly, which was consistent with the distributions of DHg and DMeHg concentrations in pore water and the aromaticity variation of soil DOM. In contrast, the CCD input significantly enhanced the enrichment of THg and MeHg in rice grains relative to CD because it significantly reduced the humification of soil DOM at all rice-growing stages while increasing the low-molecular-weight fractions in soil DOM. The THg and MeHg contents in the rice grains were significantly lower treated by RaS than those by MaS and RiS, which may be related to the higher sulfur-containing compounds such as sulfate and cysteine in rape straw or its DOM solution. Overall, DOM amendment from different agricultural sources resulted in significantly discriminative effects on the MeHg accumulation in soil and Hg enrichment in rice in the Hg-contaminated paddy field by shaping soil DOM properties.

Selenium/sulfur-modified montmorillonite materials mitigate mercury pollution in farmland.

Selenium (Se) amendment could reduce mercury (Hg) bioaccumulation in crops, but sometimes it could cause excessive Se accumulation in crops and potential Se exposure risks for humans. In this study, we designed and synthesized selenium and sulfur-modified montmorillonite materials (Se/S-Mont) to effectively reduce mercury levels and avoid excessive Se enrichment in plants. The results of pot experiments (1 g Se/S-Mont/100 g soil) and field microplot trials (0.3 g Se/S-Mont/100 g soil, 8 t/ha) showed that Se/S-Mont amendments significantly reduced the Hg concentrations in water spinach and hybrid Pennisetum by 28-68% and 57%-92% (P < 0.05), respectively, while they did not lead to excessive Se bioaccumulation in the plants. Se/S-Mont was more efficient in mitigating soil Hg pollution than adding raw materials (e.g., NaSeO3) and their combinations, and they significantly reduced the available Se fraction in the soil and the Se levels in the plants (P < 0.05). The potential mechanisms revealed by X-ray absorption near-edge spectra (XANES) and pot experiments were the adsorption and slow release of Hg, S, and Se by Se/S-Mont, the high affinity between Hg and Se, competition between Se and S, and the formation of stable complexes containing Se-S-Hg. The Se/S-Mont immobilizer was easy to prepare and required the application of small amounts, and the remediation effect was relatively stable and exhibited few negative effects; therefore, the approach showed high environmental and economic potentials.

The association between COVID-19 and cognitive performance: A Mendelian randomization analysis.

INTRODUCTION: People with COVID-19 had poorer general cognitive functioning compared to people without COVID-19. The causal link between COVID-19 and cognitive impairment is still unknown. METHODS: Mendelian randomization (MR) is a statistical approach based on genome-wide association studies (GWAS) to construct instrumental variables (IVs) and can effectively bring down the confounding bias of environmental or other disease factors, because alleles are randomly assigned to offspring. RESULTS: There was consistent evidence that cognitive performance was causally associated with COVID-19; this suggests that people with better cognitive performance are less likely to be infected with COVID-19. The reverse MR analysis treating COVID-19 as the exposure and cognitive performance as the outcome demonstrated an insignificant association, indicating the unidirectionality of the relationship. DISCUSSION: Our study provided credible evidence that cognitive performance has an impact on COVID-19. Future research should focus on long-term impact of cognitive performance on COVID-19.

Effects of Composted Agricultural Organic Materials on Mercury Methylation in Paddy Soil and Mercury Enrichment in Rice.

Many studies have shown that returning fresh straw to the field can promote mercury accumulation in crops; therefore, it is necessary to find an appropriate way to use agricultural organic materials in mercury-contaminated farmlands. In this study, pot experiments were conducted to study the effects of composted agricultural organic materials on mercury bioaccumulation in the paddy field ecosystem by adding fresh rice straw (RS), composted rice straw (CRS), cow dung (CD) and composted cow dung (CCD) to the soils. Compared with RS and CD, the CRS and CCD amendments reduced dissolved organic matter (DOM) contents in soil, but increased the aromaticity and small molecule proportion of DOM, and also increased the tartaric acid contents in soil, as well as the methylation and release of mercury in soil. However, the increased available mercury and methylmercury in the soils in the CRS and CCD treatments were not effectively absorbed by rice plants. Overall, compared with fresh organic materials, composted organic materials amendments could reduce mercury accumulation in rice to a certain extent.

Identification of LRRK2 gene related to sarcopenia and neuroticism using weighted gene co-expression network analysis.

BACKGROUND: Sarcopenia is reported to be associated with neuroticism, but the mechanisms are not fully understood. Thus, it's of vital importance to elucidate the molecular mechanism of sarcopenia and neuroticism and to explore the potential molecular target of medical therapies for sarcopenia and neuroticism. METHODS: The expression datasets (sarcopenia: GSE111006 and neuroticism: GSE60491) were downloaded from the Gene Expression Omnibus. Weighted gene co-expression network analysis (WGCNA) was used to build the gene co-expression network, screen important modules, and filter the hub genes. Genes with significance over 0.2 and a module membership over 0.8 were hub genes. The overlapped hub genes between sarcopenia and neuroticism were defined as key genes. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses were performed for the genes in modules with clinical interest. RESULTS: In this study, we identified 28 gene modules for sarcopenia and 7 for neuroticism by WGCNA. The key modules of sarcopenia and neuroticism were the tan and turquoise modules, respectively. Hub genes of sarcopenia and neuroticism were 20 genes and 107 genes, respectively. The function enrichment found that apoptosis was the common pathway for sarcopenia and neuroticism. Finally, LRRK2 was identified as key genes. LIMITATIONS: The sarcopenia dataset contained fewer samples. CONCLUSION: Based on WGCNA, our study identified apoptosis pathway and LRRK2 that acted as essential components in the etiology of sarcopenia and neuroticism, which may enhance our fundamental knowledge of the molecular mechanisms underlying the disease.

Effects of fulvic acid and humic acid from different sources on Hg methylation in soil and accumulation in rice.

Humus is often used as an organic modifier to reduce the bioaccumulation of heavy metals in plants, but the effects of different humus components from different sources on the fate of mercury (Hg) in paddy fields are still unclear. Here, fulvic acid (FA) and humic acid (HA) extracted from composted straw (CS), composted cow dung (CCD), peat soil (PM) and lignite coal (LC) were used to understand their effects on the methylation and bioaccumulation of Hg in paddy soil by pot experiments. Amendments of both FA and HA largely increased the abundance of Hg-methylating microbes and low-molecular-weight organic matters (e.g, cysteine) in paddy soil. They were also found to change the aromaticity, molecular size and Chromophoric DOM concentration of DOM, and resulted in heterogeneous effects on migration and transformation of Hg. All the FA-amended treatments increased the mobility and methylation of Hg in soil and its absorption in roots. Nevertheless, FA from different sources have heterogeneous effects on transport of Hg between rice tissues. FA-CCD and FA-PM promoted the translocation of MeHg from roots to rice grains by 32.95% and 41.12%, while FA-CS and FA-LC significantly inhibited the translocation of inorganic Hg (IHg) by 52.65% and 66.06% and of MeHg by 46.65% and 36.23%, respectively. In contrast, all HA-amended treatments reduced the mobility of soil Hg, but promoted Hg methylation in soil. Among which, HA-CCD and HA-PM promoted the translocation of MeHg in rice tissues by 88.95% and 64.10%, while its accumulation in rice grains by 28.43% and 28.69%, respectively. In general, the application of some FA and HA as organic modifiers to reduce Hg bioaccumulation in rice is not feasible.