Mercury pollution has become an important current issue as a result of its environmental effects on a global scale. The Oak Ridge Reservation, established in 1942, was the designated site for the construction of the a...Mercury pollution has become an important current issue as a result of its environmental effects on a global scale. The Oak Ridge Reservation, established in 1942, was the designated site for the construction of the atomic bomb. During a 20-year period from 1944-1963 radioactive and toxic chemical pollutants, especially mercury compounds were released into the surrounding waterways.A germination study was conducted to investigate the ability of three tree species, American sycamore (Platanus occidentalis),shortleaf pine (Pinus echinata), and loblolly pine (Pinus taeda) seeds to germinate in mercuric nitrate (Hg(NO3)2 and methylmercury chloride (CH3HgCl) solutions. A subsequent greenhouse study was conducted to assess the phytotoxic effects of different mercuric solutions on Platanus occidentalis (American Sycamore), inoculated with soils from East Fork Poplar Creek.We also measured vegetation stress by Near Infrared (NIR) spectroscopy.The wavelengths examined were those thatare specific to chlorophyll and several carotenoids, which are involved in photosynthesis: 430 nm (Chl a), 448 nm (Chl b, carotenoids), 471 nm (carotenoids), 642 nm (Chl b), 662 & 680 nm (Chl a). Principal component analysis (PCA) was performed to identify patterns in sycamore leaf spectral data.Under in vitro conditions, as mercury concentration increased above 100 mg·kg-1, germination of all species decreased, with P. echinata being the least sensitive. Germination was inhibited more when seeds were exposed to methyl mercury chloride than to mercuric nitrate. Organic species of mercury proved to be more toxic than inorganic species of mercury in our greenhouse study. Significant changes occurred in levels of all pigments sampled (p430, p448, p471, p642, p662, and p680) over the course of the experiment. NIR spectroscopy was not sensitive enough to detect other chemical changes to foliage following mercury application.展开更多
Mercuric reductase is detected in Cephalosporium tabacinum F2.The enzyme, which is an intracel- lular one,catalyzes the reduction of mercuric ions to elemental mercury,which requires NADH as an electron donor and adde...Mercuric reductase is detected in Cephalosporium tabacinum F2.The enzyme, which is an intracel- lular one,catalyzes the reduction of mercuric ions to elemental mercury,which requires NADH as an electron donor and added sulfhydryl compound.The optimum temperature and pH of the enzymatic reaction are 30℃ and 7.0- 8. 0,respectively.The enzyme activity is stable in the range of 25- 30℃ for 40min,and stable at pH 7. 0 for 2 hours. Metal ions such as Ag￣+ ,CO￣(2+), Cu￣(2+),Zh￣(2+), Mn￣(2+),Ni￣(2+) show different degrees of in- hibitory effect on the enzyme activity,other compounds such as phenylmercury acetate and potassium ferri- cyanide also partially inhibit the enzyme activity.展开更多
Objective To explore the toxic effects of mercuric chloride (HgCl 2) on vascular smooth muscle as well as its relationship to calcium antagonist. Methods By using isolated vascular tension methods, we studied the effe...Objective To explore the toxic effects of mercuric chloride (HgCl 2) on vascular smooth muscle as well as its relationship to calcium antagonist. Methods By using isolated vascular tension methods, we studied the effect of HgCl 2 on isolated rabbit aortic rings. Results HgCl 2 (1-100 μmol·L -1) caused a concentration-dependent contraction of rabbit aortic rings, which did not change with phentolamin or without endothelium. In KH solution with Ca 2+ , the maximum contraction amplitude reduced by(61.2±3.3)%. Nifedipine produced a concentration-dependent decrease of the maximum contraction amplitude. Conclusion Calcium antagonist has protective effects on vascular smooth muscle against damage induced by HgCl 2.展开更多
In order to further understand the effects of drought stress on hydraulic characteristics and the relationship between hydraulic conductivity and aquaporins or water channels of root systems of three wolfberry cultiva...In order to further understand the effects of drought stress on hydraulic characteristics and the relationship between hydraulic conductivity and aquaporins or water channels of root systems of three wolfberry cultivars(Lycium chinense Mill.),hydraulic conductivity of 2-yearold pot-grown seedlings was measured under drought stress,rewatering,and treatment with exogenous mercuric chloride andβ-mercaptoethanol.Under moderate and severe drought stress levels,the most significant decrease of hydraulic conductivity was 37.3%and 24.0%,respectively,in the‘Ningqi 5’cultivar compared with the nonstressed control.After rewatering,the rate of recovery in specific conductivity was most rapid in the‘Mengqi 1’cultivar,at 0.058 and 0.072 kg MPa^-1 m^-2 s^-1 h^-1 under moderate and severe drought stress levels,respectively.The‘Mengqi 1’cultivar had the highest recovery degree of hydraulic conductivity under two concentrations ofβ-ME(500 or 1000 lmol L^-1),reaching 82.4%and 88.5%,respectively,of the initial conductivity.The adaptive capacity of hydraulic conductivity in the‘Ningqi 5’cultivar was weaker than in the‘Ningqi 1’and‘Mengqi 1’cultivars under drought stress.The recovery capacity of hydraulic conductivity in‘Mengqi 1’cultivar was stronger than the‘Ningqi 1’and‘Ningqi 5’cultivars after rewatering.Aquaporins of the‘Ningqi 1’cultivar root systems had the highest binding affinity with mercuric chloride,which was the most likely cause in the decrease in hydraulic conductivity,whereas aquaporins of‘Mengqi 1’root systems had the weakest binding affinity.The inhibitory effect of mercuric chloride was readily eliminated byβ-mercaptoethanol in the‘Mengqi 1’cultivar.The hydraulic characteristics of this cultivar were more sensitive to drought,mercuric chloride andβ-mercaptoethanol than the other cultivars.展开更多
The fluorescent characteristics of a fluorimetric chemosensor for mercuric ion, Hg2+, employing a synthesized Rhodamine 6G derivative, have been analyzed. For that, a portable spectrofluorimeter composed of a 515 nm L...The fluorescent characteristics of a fluorimetric chemosensor for mercuric ion, Hg2+, employing a synthesized Rhodamine 6G derivative, have been analyzed. For that, a portable spectrofluorimeter composed of a 515 nm LED as excitation source, two fiber-optics and a CCD camera as detector, has been used, intended for “in situ” analysis. A highly selective Rhodamine based probe for Hg2+, that is water soluble and gives a positive response upon analyte binding, is reported. The reagent is bearing a monothiospirolactone group in a Rhodamine 6G architecture and the thiol atom served for the direct attack of thiophilic Hg2+. The fluorescence enhancement is attributed to the spirolactone ring opening and the coordination of two sulphur atoms to Hg2+ giving a 2:1 reagent: Hg2+ stoichiometry complex.展开更多
Free radicals are common outcome of normal aerobic cellular metabolism. In-built antioxidant system of body plays its decisive role in prevention of any loss due to free radicals. However, imbalanced defense mechanism...Free radicals are common outcome of normal aerobic cellular metabolism. In-built antioxidant system of body plays its decisive role in prevention of any loss due to free radicals. However, imbalanced defense mechanism of antioxidants and overproduction or incorporation of free radicals from environment to living systems leads to serious damage. It also attacks nervous system resulting in neural-degeneration. In order to evaluate the neurotoxic effect on the brain parts of mercury in our study, oxidative stress indices of enzymatic and non enzymatic components were measured in rats intoxicated with mercury (2 mg and 4 mg/kg body weight) for 60 days to adult rats. Along with gravimetry, tissue burden was also recorded. Alterations in these indices were further supported by ultrastructural studies carried out in the brain as indicated by myelin disintegration, cell organelle alterations and neuronal loss by mercury poisoning. Treatment with the antioxidant melatonin (N-acetyl 5-methoxy tryptamine, 5 mg/kg) prevented mercury exerted toxicity due to its antioxidant property. The pathological changes were also ameliorated in the brain region comparatively to support biochemical profile of brain. Thus, melatonin produced neuroprotection against mercury poisoning in rats.展开更多
The present study was performed in order to discern the effects of combined exposure to cadmium and mercury on liver function and histopathological alterations in male adult Wistar rats. In the present investigation, ...The present study was performed in order to discern the effects of combined exposure to cadmium and mercury on liver function and histopathological alterations in male adult Wistar rats. In the present investigation, cadmium (100 mg/l) and mercury (25 mg/l) were administered orally for 10 weeks separately or in combination. The rational for studying cadmium and mercury is that both of these metals are encountered frequently in the same contaminated areas. In liver, the activities of serum alanine aminotransferase (ALT) and aspartate amino tranferase (AST) increased significantly in the cadmium (Cd) and mercury (Hg) alone or in combination (Cd + Hg) compared to the control suggesting that both cadmium and mercury cause hepatotoxicity spatially when co-administrated. We noted an increase in serum lactate dehydrogenase (LDH) activity in Cd and combined Cd + Hg treated groups while it decreased in Hg treated group. There was no statistically significant change in the level of total bilirubilin. Serum urea concentration showed a significant increase in the Cd and Hg groups compared to the control group. However an increase in serum creatinine concentration was noted only in the combined treated rats showing that renal insufficiency is more serious in the co-exposed group. Light microscopic examination indicated severe histological changes in the two organs under Cd and mercury influence. Results of the present investigation clearly showed that mercury has profound effects of hepatic handling of cadmium (synergistic effect) as shown by histological and biochemical results. Moreover, we observed a antagonist effect between these two toxic metals on kidney markers such as urea.展开更多
Up to 1980 s,the most used preservative for herbaria specimens was HgCl2,sublimating at ambient air conditions;ionic Hg then reduces to Hg0(gaseous elemental mercury,GEM)and diffuses throughout poor ventilated environ...Up to 1980 s,the most used preservative for herbaria specimens was HgCl2,sublimating at ambient air conditions;ionic Hg then reduces to Hg0(gaseous elemental mercury,GEM)and diffuses throughout poor ventilated environments.High GEM levels may indeed persist for decades,representing a health hazard.In this study,we present new GEM data from the Central Italian Herbarium and Tropical Herbarium Studies Centre of the University of Florence(Italy).These herbaria host one of the largest collection of plants in the world.Here,HgCl2 was documented as plant preservative up to the 1920 s.GEM surveys were conducted in July 2013 and July and December 2017,to account for temporal and seasonal variations.Herbaria show GEM concentrations well above those of external locations,with peak levels within specimen storage cabinets,exceeding 50,000 ng/m3.GEM concentrations up to^7800 ng/m3 were observed where the most ancient collections are stored and no ventilation systems were active.On the contrary,lower GEM concentrations were observed at the first floor.Here,lower and more homogeneously distributed GEM concentrations were measured in 2017 than in 2013 since the air-conditioning system was updated in early2017.GEM concentrations were similar to other herbaria worldwide and lower than Italian permissible exposure limit of 20,000 ng/m3(8-hr working day).Our results indicate that after a century from the latest HgCl2 treatment GEM concentrations are still high,i.e.,the treatment itself is almost irreversible.Air conditioning and renewing is probably the less expensive and more effective method for GEM lowering.展开更多
Exposure to mercuric chloride(HgCl2;5 mg kg–1 body weight;i.p.)induced oxidative stress in mice and substantially increased lipid peroxidation(LPO)and oxidized glutathione(GSSG)levels,decreased the level of reduced g...Exposure to mercuric chloride(HgCl2;5 mg kg–1 body weight;i.p.)induced oxidative stress in mice and substantially increased lipid peroxidation(LPO)and oxidized glutathione(GSSG)levels,decreased the level of reduced glu-tathione(GSH)and various antioxidant enzymes in liver and also increased the activities of liver marker enzymes in serum.Therapy with propolis extract,a resinous wax-like beehive product(200 mg kg–1 orally,after mercury administration),for 3 days inhibited LPO and the formation of GSSG and increased the level of GSH in the liver.Release of serum transaminases,alkaline phosphatase,lactate dehydrogenase and-glutamyl transpeptidase were significantly restored after propolis treatment.The activities of antioxidant enzymes,that is,superoxide dismutase,catalase,glutathione-S-transferase and glucose-6-phosphate dehydrogenase,were also concomitantly restored towards normal levels after propolis administration.These observations clearly demonstrate that propolis treatment augments antioxidant defense against mercury-induced toxicity and provide evidence that propolis has therapeutic potential as a hepatoprotective agent.展开更多
文摘Mercury pollution has become an important current issue as a result of its environmental effects on a global scale. The Oak Ridge Reservation, established in 1942, was the designated site for the construction of the atomic bomb. During a 20-year period from 1944-1963 radioactive and toxic chemical pollutants, especially mercury compounds were released into the surrounding waterways.A germination study was conducted to investigate the ability of three tree species, American sycamore (Platanus occidentalis),shortleaf pine (Pinus echinata), and loblolly pine (Pinus taeda) seeds to germinate in mercuric nitrate (Hg(NO3)2 and methylmercury chloride (CH3HgCl) solutions. A subsequent greenhouse study was conducted to assess the phytotoxic effects of different mercuric solutions on Platanus occidentalis (American Sycamore), inoculated with soils from East Fork Poplar Creek.We also measured vegetation stress by Near Infrared (NIR) spectroscopy.The wavelengths examined were those thatare specific to chlorophyll and several carotenoids, which are involved in photosynthesis: 430 nm (Chl a), 448 nm (Chl b, carotenoids), 471 nm (carotenoids), 642 nm (Chl b), 662 & 680 nm (Chl a). Principal component analysis (PCA) was performed to identify patterns in sycamore leaf spectral data.Under in vitro conditions, as mercury concentration increased above 100 mg·kg-1, germination of all species decreased, with P. echinata being the least sensitive. Germination was inhibited more when seeds were exposed to methyl mercury chloride than to mercuric nitrate. Organic species of mercury proved to be more toxic than inorganic species of mercury in our greenhouse study. Significant changes occurred in levels of all pigments sampled (p430, p448, p471, p642, p662, and p680) over the course of the experiment. NIR spectroscopy was not sensitive enough to detect other chemical changes to foliage following mercury application.
文摘Mercuric reductase is detected in Cephalosporium tabacinum F2.The enzyme, which is an intracel- lular one,catalyzes the reduction of mercuric ions to elemental mercury,which requires NADH as an electron donor and added sulfhydryl compound.The optimum temperature and pH of the enzymatic reaction are 30℃ and 7.0- 8. 0,respectively.The enzyme activity is stable in the range of 25- 30℃ for 40min,and stable at pH 7. 0 for 2 hours. Metal ions such as Ag￣+ ,CO￣(2+), Cu￣(2+),Zh￣(2+), Mn￣(2+),Ni￣(2+) show different degrees of in- hibitory effect on the enzyme activity,other compounds such as phenylmercury acetate and potassium ferri- cyanide also partially inhibit the enzyme activity.
文摘Objective To explore the toxic effects of mercuric chloride (HgCl 2) on vascular smooth muscle as well as its relationship to calcium antagonist. Methods By using isolated vascular tension methods, we studied the effect of HgCl 2 on isolated rabbit aortic rings. Results HgCl 2 (1-100 μmol·L -1) caused a concentration-dependent contraction of rabbit aortic rings, which did not change with phentolamin or without endothelium. In KH solution with Ca 2+ , the maximum contraction amplitude reduced by(61.2±3.3)%. Nifedipine produced a concentration-dependent decrease of the maximum contraction amplitude. Conclusion Calcium antagonist has protective effects on vascular smooth muscle against damage induced by HgCl 2.
基金the National Natural Science Foundation of China(Grant No.31560380)Chief Expert of Modern Agricultural Traditional Chinese Medicine Industry System in Gansu Province(GARS-ZYC-1)the Open Project of Qinghai Key Laboratory of Qinghai-Tibet Plateau Biological Resources(Grant No.2017-ZJ-Y10)。
文摘In order to further understand the effects of drought stress on hydraulic characteristics and the relationship between hydraulic conductivity and aquaporins or water channels of root systems of three wolfberry cultivars(Lycium chinense Mill.),hydraulic conductivity of 2-yearold pot-grown seedlings was measured under drought stress,rewatering,and treatment with exogenous mercuric chloride andβ-mercaptoethanol.Under moderate and severe drought stress levels,the most significant decrease of hydraulic conductivity was 37.3%and 24.0%,respectively,in the‘Ningqi 5’cultivar compared with the nonstressed control.After rewatering,the rate of recovery in specific conductivity was most rapid in the‘Mengqi 1’cultivar,at 0.058 and 0.072 kg MPa^-1 m^-2 s^-1 h^-1 under moderate and severe drought stress levels,respectively.The‘Mengqi 1’cultivar had the highest recovery degree of hydraulic conductivity under two concentrations ofβ-ME(500 or 1000 lmol L^-1),reaching 82.4%and 88.5%,respectively,of the initial conductivity.The adaptive capacity of hydraulic conductivity in the‘Ningqi 5’cultivar was weaker than in the‘Ningqi 1’and‘Mengqi 1’cultivars under drought stress.The recovery capacity of hydraulic conductivity in‘Mengqi 1’cultivar was stronger than the‘Ningqi 1’and‘Ningqi 5’cultivars after rewatering.Aquaporins of the‘Ningqi 1’cultivar root systems had the highest binding affinity with mercuric chloride,which was the most likely cause in the decrease in hydraulic conductivity,whereas aquaporins of‘Mengqi 1’root systems had the weakest binding affinity.The inhibitory effect of mercuric chloride was readily eliminated byβ-mercaptoethanol in the‘Mengqi 1’cultivar.The hydraulic characteristics of this cultivar were more sensitive to drought,mercuric chloride andβ-mercaptoethanol than the other cultivars.
基金supported by the Ministerio de Ciencia e Innovacion of Spain(Project CTQ2011-25388)the Junta de Extremadura(Consolidation Project GR10033 of Research Group FQM003 co-financed by European FEDER Funds).
文摘The fluorescent characteristics of a fluorimetric chemosensor for mercuric ion, Hg2+, employing a synthesized Rhodamine 6G derivative, have been analyzed. For that, a portable spectrofluorimeter composed of a 515 nm LED as excitation source, two fiber-optics and a CCD camera as detector, has been used, intended for “in situ” analysis. A highly selective Rhodamine based probe for Hg2+, that is water soluble and gives a positive response upon analyte binding, is reported. The reagent is bearing a monothiospirolactone group in a Rhodamine 6G architecture and the thiol atom served for the direct attack of thiophilic Hg2+. The fluorescence enhancement is attributed to the spirolactone ring opening and the coordination of two sulphur atoms to Hg2+ giving a 2:1 reagent: Hg2+ stoichiometry complex.
文摘Free radicals are common outcome of normal aerobic cellular metabolism. In-built antioxidant system of body plays its decisive role in prevention of any loss due to free radicals. However, imbalanced defense mechanism of antioxidants and overproduction or incorporation of free radicals from environment to living systems leads to serious damage. It also attacks nervous system resulting in neural-degeneration. In order to evaluate the neurotoxic effect on the brain parts of mercury in our study, oxidative stress indices of enzymatic and non enzymatic components were measured in rats intoxicated with mercury (2 mg and 4 mg/kg body weight) for 60 days to adult rats. Along with gravimetry, tissue burden was also recorded. Alterations in these indices were further supported by ultrastructural studies carried out in the brain as indicated by myelin disintegration, cell organelle alterations and neuronal loss by mercury poisoning. Treatment with the antioxidant melatonin (N-acetyl 5-methoxy tryptamine, 5 mg/kg) prevented mercury exerted toxicity due to its antioxidant property. The pathological changes were also ameliorated in the brain region comparatively to support biochemical profile of brain. Thus, melatonin produced neuroprotection against mercury poisoning in rats.
文摘The present study was performed in order to discern the effects of combined exposure to cadmium and mercury on liver function and histopathological alterations in male adult Wistar rats. In the present investigation, cadmium (100 mg/l) and mercury (25 mg/l) were administered orally for 10 weeks separately or in combination. The rational for studying cadmium and mercury is that both of these metals are encountered frequently in the same contaminated areas. In liver, the activities of serum alanine aminotransferase (ALT) and aspartate amino tranferase (AST) increased significantly in the cadmium (Cd) and mercury (Hg) alone or in combination (Cd + Hg) compared to the control suggesting that both cadmium and mercury cause hepatotoxicity spatially when co-administrated. We noted an increase in serum lactate dehydrogenase (LDH) activity in Cd and combined Cd + Hg treated groups while it decreased in Hg treated group. There was no statistically significant change in the level of total bilirubilin. Serum urea concentration showed a significant increase in the Cd and Hg groups compared to the control group. However an increase in serum creatinine concentration was noted only in the combined treated rats showing that renal insufficiency is more serious in the co-exposed group. Light microscopic examination indicated severe histological changes in the two organs under Cd and mercury influence. Results of the present investigation clearly showed that mercury has profound effects of hepatic handling of cadmium (synergistic effect) as shown by histological and biochemical results. Moreover, we observed a antagonist effect between these two toxic metals on kidney markers such as urea.
文摘Up to 1980 s,the most used preservative for herbaria specimens was HgCl2,sublimating at ambient air conditions;ionic Hg then reduces to Hg0(gaseous elemental mercury,GEM)and diffuses throughout poor ventilated environments.High GEM levels may indeed persist for decades,representing a health hazard.In this study,we present new GEM data from the Central Italian Herbarium and Tropical Herbarium Studies Centre of the University of Florence(Italy).These herbaria host one of the largest collection of plants in the world.Here,HgCl2 was documented as plant preservative up to the 1920 s.GEM surveys were conducted in July 2013 and July and December 2017,to account for temporal and seasonal variations.Herbaria show GEM concentrations well above those of external locations,with peak levels within specimen storage cabinets,exceeding 50,000 ng/m3.GEM concentrations up to^7800 ng/m3 were observed where the most ancient collections are stored and no ventilation systems were active.On the contrary,lower GEM concentrations were observed at the first floor.Here,lower and more homogeneously distributed GEM concentrations were measured in 2017 than in 2013 since the air-conditioning system was updated in early2017.GEM concentrations were similar to other herbaria worldwide and lower than Italian permissible exposure limit of 20,000 ng/m3(8-hr working day).Our results indicate that after a century from the latest HgCl2 treatment GEM concentrations are still high,i.e.,the treatment itself is almost irreversible.Air conditioning and renewing is probably the less expensive and more effective method for GEM lowering.
基金The authors wish to thank the Indian Council of Medical Research,New Delhi,India(45/15/2002/PHA/BMS)for financial assistance.
文摘Exposure to mercuric chloride(HgCl2;5 mg kg–1 body weight;i.p.)induced oxidative stress in mice and substantially increased lipid peroxidation(LPO)and oxidized glutathione(GSSG)levels,decreased the level of reduced glu-tathione(GSH)and various antioxidant enzymes in liver and also increased the activities of liver marker enzymes in serum.Therapy with propolis extract,a resinous wax-like beehive product(200 mg kg–1 orally,after mercury administration),for 3 days inhibited LPO and the formation of GSSG and increased the level of GSH in the liver.Release of serum transaminases,alkaline phosphatase,lactate dehydrogenase and-glutamyl transpeptidase were significantly restored after propolis treatment.The activities of antioxidant enzymes,that is,superoxide dismutase,catalase,glutathione-S-transferase and glucose-6-phosphate dehydrogenase,were also concomitantly restored towards normal levels after propolis administration.These observations clearly demonstrate that propolis treatment augments antioxidant defense against mercury-induced toxicity and provide evidence that propolis has therapeutic potential as a hepatoprotective agent.
