[Show abstract][Hide abstract] ABSTRACT: Mercury (Hg) is a global pollutant that poses a serious threat to human and the environment. Rice was found as an important source for human exposure to Hg in some areas. In this study, the transportation and transformation of IHg and MeHg in rice plants exposed to IHg or MeHg were investigated. The IHg and MeHg concentrations in rice roots and shoots collected every five days were analyzed by HPLC-ICP-MS and SR-XANES. When exposed to MeHg, the percent of IHg in rice roots and shoots increased while MeHg decreased significantly, suggesting prominent demethylation of MeHg occurred. However no notable MeHg was found in both roots and shoots of rice plant when exposed to IHg. SR-XANES analysis further confirmed the demethylation of MeHg with rice. This study provides a new finding that demethylation of MeHg could occur in growing rice, which may be a self-defense process of rice plant.
Full-text · Article · Mar 2016 · Environmental Pollution
[Show abstract][Hide abstract] ABSTRACT: The toxicity mechanisms of rice roots under inorganic mercury (IHg) or methylmercury (MeHg) stress were investigated using metalloproteomic approaches. Rice seedlings were cultivated in nutrient solutions with IHg or MeHg for three weeks. Proteins were extracted from the roots and separated by two-dimensional electrophoresis (2-DE). Differentially expressed proteins were analyzed using ESI-MS/MS and identified by PMF. 26 and 29 protein spots were differentially expressed in the IHg- and MeHg-exposed roots, respectively. The proteins responsive to Hg exposure are involved in antioxidative defense, sulfur and glutathione metabolism, carbohydrate and energy metabolism, programmed cell death, and pathogen defense. Chitinase and salt stress-induced proteins exhibited a greater differentially expression in response to MeHg stress compared to IHg stress. Hg-binding proteins were detected by the combined use of 1-DE, SRXRF, and ESI-MS/MS. The results showed that Hg was bound to proteins of 15-25 kDa in rice roots under Hg stress. The Hg contents in the band under IHg stress were remarkably higher than those under MeHg. Hg binds to proteins, which leads to irreversible damage of root growth. Rice roots changed the related protein expression levels in response to Hg stress. These results may provide new insights into the mechanism of toxicity of IHg and MeHg in rice.
[Show abstract][Hide abstract] ABSTRACT: Mercury is a potent neurotoxin, which causes serious and permanent damage to biota including human beings. Nanomaterials like gold have been used to detect mercury, especially the mercuric ions in recent years, but few have been done on the determination of methylmercury (CH3Hg+). In this study, we present a simple, selective and sensitive method for the determination of CH3Hg+ coexisting with Hg2+ based on the fluorescence quenching of bovine serum albumin (BSA) stabilized gold nanoclusters (BSA-Au NCs). It was found that the fluorescence quenching of BSA-Au NCs by Hg2+ is stronger than CH3Hg+ at the same concentration. Hg2+ can be masked by EDTA while CH3Hg+ is less affected. Therefore, the determination of CH3Hg+ was achieved through EDTA masking. The detection limit for CH3Hg+ is 35 nmol/L after masking Hg2+ with EDTA. This method has been successfully applied to quantify CH3Hg+ in rice paddy water from Qingzhen, Guizhou and tap water from Beijing.
No preview · Article · Jan 2016 · Journal of Nanoscience and Nanotechnology
[Show abstract][Hide abstract] ABSTRACT: Mercury is toxic with widespread contamination. Highly sensitive and selective approaches for mercury analysis are desired. Although conventional techniques are accurate and sensitive in the determination of mercury, these procedures are time-consuming, labor-intensive and dependent heavily on expensive instrumentation. In recent years, nanomaterial-based approaches have been proved to be effective alternatives in the detection and speciation of mercury. In this review, the development of different nanomaterial-based approaches was summarized, as well as their utilization for the detection of mercury in environmental and biological samples, such as gold nanomaterials, carbon nanomaterials, quantum dots and so on. Moreover, the speciation of mercury using nanomaterials was also reviewed.
[Show abstract][Hide abstract] ABSTRACT: Background and aims
Iron plaque can affect the absorption and accumulation of metal(loid)s in plants. However, it is still unclear whether iron plaque plays different roles in the accumulation of different mercury species in rice plants. The aims of this study are 1) to explore the adsorption of IHg and MeHg onto iron plaque, 2) to investigate the influence of iron plaque on the absorption, translocation of IHg and MeHg in rice plants, 3) to explore whether the process of methylation and demethylation of Hg in vivo occurs in rice plants, and 4) to investigate the effects of iron plaque on the IHg and MeHg transformation in rice.
The seedlings were cultivated in an Fe2+ solution for 24 h to induce the iron plaque and then transferred into a nutrient solution containing 500 μg/L HgCl2 or MeHgCl for 72 h. The Hg content in the iron plaque and rice seedlings was measured by ICP-MS. The chemical forms of Hg in the rice seedlings were determined with HPLC-ICP-MS and XANES.
Both IHg and MeHg, particularly MeHg, could be adsorbed by iron plaque. The IHg content of the root and the MeHg content in both the roots and shoots decreased markedly with the increase in iron plaque. The Hg in the root was mainly in the form of RS-Hg-SR with the exposure to HgCl2 and in the form of CH3-Hg-SR and RS-Hg-SR (4:1) with the exposure to MeHgCl. The iron plaque did not change the chemical forms of Hg in the rice plants.
Iron plaque greatly decreased the absorption and translocation of both IHg and MeHg in rice seedlings. The demethylation of MeHg occurred in rice plants (in vivo) regardless the formation of iron plaque. This work sheds some light on the understanding of different pathways between IHg and MeHg in rice plants.
[Show abstract][Hide abstract] ABSTRACT: A comprehensive approach that can separate and quantify selenium (Se) in seleno-proteins in Se-enriched yeast was developed. The Se-containing compounds in Se-enriched yeast were first extracted, then the fraction of Se-containing proteins in the supernatant was analyzed by 2-dimensional electrophoresis (2-DE) and synchrotron radiation X-ray fluorescence (SR-XRF). The detection limits (DL) of SR-XRF analysis for Se quantification in Se-containing proteins after 2-DE separation was calculated to be 0.20 μg g-1, which is suitable for Se quantification in the Se-containing spots exhibited on the 2-D gel. After scanned by SR-XRF, Only spots with a mean Se content exceeding twice the DL of SR-XRF were considered to be seleno-proteins. In this way, a total of 157 Se-containing spots in the gel were visually separated. Se contents in all the Se-containing proteins of different molecular weight were quantified. The total Se content on the 2-D gel was calculated to be 126.56 μg g-1, which covered most of the seleno-proteins on the 2-D gel.
Full-text · Article · Jun 2015 · Journal of Analytical Atomic Spectrometry
[Show abstract][Hide abstract] ABSTRACT: Aims The consumption of rice grain produced in mercury (Hg) contaminated soil was identified as a major route of dietary Hg exposure. The aims were 1) to determine the most suitable concentration of Se that can lead to least Hg accumulation in rice grain in real Hg contaminated paddy field in Qingzhen, and 2) to elucidate the possible mechanism of the protection against the phytotoxicity of Hg in rice by Se. Methods Rice plants were treated with different concentrations (0, 0.01, 0.1, 0.5, 1 and 5 μg/mL) of sodium selenite in a real paddy field in Qingzhen, Guizhou, China. The concentrations of Hg and Se in soil, stream water, rice tissues, and the seed setting rate (SSR) and thousand seed weight (TSW) were checked. The distribution and chemical forms of Hg and Se in rice root were studied by XRF and XAS. Results Treating the rice plants with 0.5 μg/mL of sodium selenite achieved the lowest Hg accumulation in rice grain while the highest SSR and TSW. In rice root, XRF found decreased Hg uptake, and XAS found Hg-Se complexes were formed. These findings, together with the formation of biological barriers like iron plaque, could explain the decreased accumulation of Hg in rice grain at Se levels below 0.5 μg/mL. Se concentrations over 0.5 μg/mL led to increased Hg accumulation and decreased SSR and TSW, which were ascribed to the significantly increased Se accumulation in rice grain. Conclusions This field study suggest that treatment with appropriate level of Se (0.5 μg/mL in this study) is an efficient way to reduce Hg accumulation in rice and increase rice yield and quality, thereafter to protect the health of the rice-dependent populations in Hg-contaminated area.
[Show abstract][Hide abstract] ABSTRACT: To predict potential medical value or toxicity of nanoparticles (NPs), it is necessary to understand the chemical transformation during intracellular processes of NPs. However, it is a grand challenge to capture a high-resolution image of metallic NPs in a single cell and the chemical information of intracellular NPs. Here, by integrating synchrotron radiation-beam transmission X-ray microscopy (SR-TXM) and SR-X-ray absorption near edge structure (SR-XANES) spectrometry, we successfully capture the 3D distribution of silver NPs (AgNPs) inside a single human monocyte (THP-1), associated with the chemical transformation of silver. The results reveal that the cytotoxicity of AgNPs is largely due to the chemical transformation of particulate silver from elemental silver (Ag0)n, to Ag+ ions and Ag-O-, then Ag-S- species. These results provide direct evidence in the long-lasting debate on whether the nanoscale or the ionic form dominates the cytotoxicity of silver nanoparticles. Further, the present approach provides an integrated strategy capable of exploring the chemical origins of cytotoxicity of metallic nanoparticles.
[Show abstract][Hide abstract] ABSTRACT: Background:
Toxic element exposure and essential trace element consumption may have changed after the Chinese economy transformed to a market-oriented system.The objectives of this study were to measure urinary concentrations of toxic (arsenic,cadmium, lead) and essential trace (selenium, zinc, copper) elements among rural residents in Hainan, China and to examine if variations in economic development are linked to differences in toxic and trace element exposure.
We conducted a questionnaire-based survey and undertook anthropometric measurements of residents aged .20 years (n = 599).Urinary samples were collected and analyzed using inductively coupled plasma mass spectrometry.
The median (ƒÊg/g creatinine) element concentrations were:arsenic, 73.2; cadmium, 1.8; lead, 3.1; selenium, 36.5; zinc, 371; and copper, 11.0. Intra-community variation in element concentrations was explained by age (arsenic,cadmium, zinc and copper), sex (arsenic, cadmium and selenium: higher in females;zinc: higher in males), body mass index (cadmium) and individual involvement in the market economy as indexed by agrochemical use (lead and selenium). The degree of community-level economic development, which was determined by the proportion of people living in better housing among the study communities, was positively associated with cadmium concentration.
The degree of community-level economic development was positively associated with urinary cadmium concentration while individual involvement in the market economy was positively associated with lead and selenium.
Full-text · Article · Dec 2014 · International journal of environmental research and public health
[Show abstract][Hide abstract] ABSTRACT: Rice cultured in Hg- and/or Se-contaminated fields is an important food source of human Hg/Se intake. There are elevated Hg and Se levels in the soil of the Wanshan District, Guizhou Province. Here we attempted to explore how a Hg antagonist, Se, modulates the absorption and accumulation of inorganic mercury (IHg) and methylmercury (MeHg) in rice. The effects of Se on the content and transportation of Hg in hydroponic and soil cultured rice plants were examined. The results show that IHg mainly accumulated in the rice roots, but some also accumulated in the rice grain. In comparison to IHg, MeHg can be concentrated in the rice grain, and the proportion of MeHg in the rice grain may account for above 40% of the total Hg. Se can protect against Hg phytotoxicity in rice and inhibit IHg accumulation in rice tissues, but was not remarkable for MeHg at a low dosage exposure level in this study. These discrepancies imply mechanistic differences between IHg and MeHg absorption and accumulation in rice. This study illustrates that Se plays an important role in modulating Hg uptake, transportation and accumulation in rice. Therefore, Se is considered to be a naturally existing element that effectively reduces Hg accumulation in rice, which may have significant implications for food safety.
[Show abstract][Hide abstract] ABSTRACT: The number and mass concentration, size distribution, and the concentration of 16 elements were studied in aerosol samples during the Spring Festival celebrations in 2013 in Beijing, China. Both the number and mass concentration increased sharply in a wide range from 10 nm to 10 μm during the firecrackers and fireworks activities. The prominent increase of the number concentration was in 50 nm-500 nm with a peak of 1.7 × 10(5)/cm(3) at 150 nm, which is 8 times higher than that after 1.5 h. The highest mass concentration was in 320-560 nm, which is 4 times higher than the control. K, Mg, Sr, Ba and Pb increased sharply during the firework activities in PM10. Although the aerosol emission from firework activities is a short-term air quality degradation event, there may be a substantial hazard arising from the chemical composition of the emitted particles.
Full-text · Article · Jun 2014 · Environmental Pollution
[Show abstract][Hide abstract] ABSTRACT: We aim to investigate the biological effects of copper particles on the murine brain and their underlying mechanism after nasal instillation of copper particles. We choose different sizes and different concentrations of copper nanoparticles for mice intranasal use. Within one week, the mice were sacrificed. Pathological lesions of glial cells were detected by immunohistochemical assay. Immunohistochemical assay reveals that glial fibrillary acidic protein (GFAP) increased significantly in all experimental groups, especially in nanocopper groups. The ultrastructure of nerve cells was observed through TEM, whose results show that there were chromatin congregation and mitochondria shrinkage in the olfactory cells, and that there was increase of endoplasmic reticulum and disassociation of endoplasmic reticulum ribosomes in hippocampus, particularly in the nanocopper-groups. Oxidative stress indexes were determined with colorimetric methods. There was no significant increase in the antioxidative enzymes (GPX, GST, SOD) in brain tissues; however, significant increase of malondiadehyde (MDA) contents was only found in the Cu nanoparticle-exposed mice at the high dose of 40 mg per kg body weight. Based on the investigation into the biological effects of copper nanoparticles (23.5 nm) after intranasal instillation to the mice, we have found that copper particles can indeed enter into the olfactory bulb and then the deeper brain. The inhalation of high dose copper nanoparticles can induce severer lesions of brain in the experimental mice. The underlying mechanism of copper nanoparticles causing severe brain damage bears little connection with oxidative stress.
No preview · Article · Jun 2014 · Journal of Nanoscience and Nanotechnology
[Show abstract][Hide abstract] ABSTRACT: Health impacts of inhalation exposure to engineered nanomaterials have attracted increasing attention. In this paper, integrated analytical techniques with high sensitivity were used to study the brain translocation and potential impairment induced by intranasally instilled copper nanoparticles (CuNPs). Mice were exposed to CuNPs in three doses (1, 10, 40 mg/kg bw). The body weight of mice decreased significantly in the 10 and 40 mg/kg group (p < 0.05) but recovered slightly within exposure duration. Inductively coupled plasma mass spectrometry (ICP-MS) analysis showed that CuNPs could enter the brain. Altered distribution of some important metal elements were observed by synchrotron radiation X-ray fluorescence (SRXRF). H&E Staining and immunohistochemical analysis showed that CuNPs produced damages to nerve cells and astrocyte might be the one of the potential targets of CuNPs. The changes of neurotransmitter levels in different brain regions demonstrate that the dysfunction occurred in exposed groups. These data indicated that CuNPs could enter the brain after nasal inhalation and induced damages to the central nervous system (CNS). Integration of effective analytical techniques for systematic investigations is a promising direction to better understand the biological activities of nanomaterials.
No preview · Article · Apr 2014 · Toxicology Letters
[Show abstract][Hide abstract] ABSTRACT: To study the arsenic distribution, speciation, its effects on the balance of other elements and the DNA damage by subchronic arsenite exposure in mice.
The 8-week-old C57BL/6N mice were matched by weight and divided into control group and supplementation group, which were given 0 or 10 microg/ml of sodium arsenite in the drinking water, and continuous exposed for 6 months.
Arsenic was found in various tissues and organs. The highest ones were in the kidney, lung and liver, reached (563.9 +/- 222.5), (458.6 +/- 191.0) and (279.8 +/- 81.2) ng/g, respectively while the lowest in the blood and brain, reached (82.2 +/- 26.7) ng/ml and (101.8 +/- 30.1) ng/g, respectively. Arsenic exists mainly in the form of dimethylarsinous acid (DMA). Compared to the control group, there was a significant difference (P < 0.05) between arsenic and chromium, copper, zinc, selenium, lead in some organs of arsenic exposed group, but not cadmium. Furthermore, the 8-hydroxydeoxyguanosine (8-OHdG) level of the exposed group was (149.1 +/- 1.0) ng/ml, which was significantly higher than the control group of (76.4 +/- 27.9) ng/ml.
Arsenic accumulated in various tissues and organs mainly in the form of DMA, which affected the balance of chromium, copper, zinc, selenium and lead in the body, and led to DNA damage after subchronic exposure.
No preview · Article · Sep 2013 · Wei sheng yan jiu = Journal of hygiene research
[Show abstract][Hide abstract] ABSTRACT: Mercury is one of the most hazardous pollutants in the environment. In this paper, the structural change of human hair induced by mercury exposure was studied. Human hair samples were, respectively, collected from the normal Beijing area and the Hg-contaminated Wanshan area of the Guizhou Province, China. Inductively Coupled Plasma Mass Spectroscopy was used to detect the element contents. Small angle x-ray scattering technique was used to probe the structural change. Three reflections with 8.8, 6.7 and 4.5-nm spacing were compared between the normal and the Hg-contaminated hair samples. The results confirm that the 4.5-nm reflection is from the ordered fibrillar structure of glycosaminoglycan (GAG) in proteoglycan (PG) that composes the matrix around the intermediate filaments. The increase of Ca content makes the regular orientated fibrillar structure of GAG transform to a random orientated one, broadening the angular extent of the reflection with 4.5-nm spacing. However, over-dose Hg makes the core proteins where the ordered fibrils of GAG are attached become coiled, which destroys the ordered arrangements of fibrillar GAG in PG, resulting in the disappearance of the reflections with 4.5-nm spacing. The disappearance of the 4.5-nm reflection can be used as a bio-indicator of over-dose Hg-contamination to human body. A supercoiled-coil model of hair nanoscale structure and a possible mechanism of mercury effect in human hair are proposed in this paper.
No preview · Article · Aug 2013 · Environmental Science & Technology
[Show abstract][Hide abstract] ABSTRACT: The response of E. coli to Hg(2+) exposure was investigated using proteomic and metalloproteomic approaches. E. coli was cultured in the LB medium containing HgCl2 and/or selenomethionine. The growth curve of E. coli was measured to estimate the toxicity of Hg(2+) or selenomethionine. After two-dimensional gel electrophoresis (2-DE), distribution of Hg in 2-DE gel was detected with synchrotron radiation X-ray fluorescence (SRXRF) at 4W1B, Beijing Synchrotron Radiation Facility. The proteins with differential expression and those containing Hg were identified with electrospray ionization tandem mass spectrometry (ESI-MS/MS) and peptide mass fingerprinting analysis. The results showed that Hg(2+) can inhibit the growth of E. coli, while supplement of selenomethionine can shorten the lag period induced by Hg(2+), indicating an antagonistic effect of selenomethionine against Hg(2+) toxicity. Mechanistically, Hg was observed to be able to bind pyruvate kinase, a glycolytic enzyme, and modulate the expression of five other proteins, including down-regulation of outer membrane protein W and up-regulation of transcription termination factor rho, cysteine synthase, transaldolase A and alkyl hydroperoxide reductase subunit C. Therefore, our results indicated that mercury may influence osmosis of plasma membrane, antioxidant defense, and glycometabolism of the microorganism. This study demonstrates the high sensitivity of SRXRF in identifying metal-associated proteins compared to conventional proteomic approaches.
[Show abstract][Hide abstract] ABSTRACT: Combined pollution of selenium (Se) and mercury (Hg) has been known in Wanshan district (Guizhou Province, China). A better understanding of how Se and Hg interact in plants and the phytotoxicity thereof will provide clues about how to avoid or mitigate adverse effects of Se/Hg on local agriculture. In this study, the biological activity of Se has been investigated in garlic with or without Hg exposure. Se alone can promote garlic growth at low levels (<0.1 mg L(-1)), whereas it inhibits garlic growth at high levels (>1 mg L(-1)). The promotive effect of Se in garlic can be enhanced by low Hg exposure (<0.1 mg L(-1)). When both Se and Hg are at high levels, there is a general antagonistic effect between these two elements in terms of phytotoxicity. Inductively coupled plasma mass spectrometry (ICP-MS) data suggest that Se is mainly concentrated in garlic roots, compared to the leaves and the bulbs. Se uptake by garlic in low Se medium (<0.1 mg L(-1)) can be significantly enhanced as Hg exposure levels increase (P < 0.05), while it can be inhibited by Hg when Se exposure levels exceed 1 mg L(-1). The synchrotron radiation X-ray fluorescence (SRXRF) mapping further shows that Se is mainly concentrated in the stele of the roots, bulbs and the veins of the leaves, and Se accumulation in garlic can be reduced by Hg. The X-ray absorption near edge structure (XANES) study indicates that Se is mainly formed in C-Se-C form in garlic. Hg can decrease the content of inorganic Se mainly in SeO3(2-) form in garlic while increasing the content of organic Se mainly in C-Se-C form (MeSeCys and its derivatives). Hg-mediated changes in Se species along with reduced Se accumulation in garlic may account for the protective effect of Hg against Se phytotoxicity.