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Sample records for methylmercury exposure immunofluorescent

  1. Methylmercury Exposure and Health Effects

    PubMed Central

    Hong, Young-Seoub; Kim, Yu-Mi

    2012-01-01

    Methylmercury is a hazardous substance that is of interest with regard to environmental health, as inorganic mercury circulating in the general environment is dissolved into freshwater and seawater, condensed through the food chain, ingested by humans, and consequently affects human health. Recently, there has been much interest and discussion regarding the toxicity of methylmercury, the correlation with fish and shellfish intake, and methods of long-term management of the human health effects of methylmercury. What effects chronic exposure to a low concentration of methylmercury has on human health remains controversial. Although the possibility of methylmercury poisoning the heart and blood vessel system, the reproductive system, and the immune system is continuously raised and discussed, and the carcinogenicity of methylmercury is also under discussion, a clear conclusion regarding the human health effects according to exposure level has not yet been drawn. The Joint FAO/WHO Expert Committee on Food Additives proposed to prepare additional fish and shellfish intake recommendations for consumers based on the quantified evaluation of the hazardousness of methylmercury contained in fish and shellfish, methylmercury management in the Korea has not yet caught up with this international trend. Currently, the methylmercury exposure level of Koreans is known to be very high. The starting point of methylmercury exposure management is inorganic mercury in the general environment, but food intake through methylation is the main exposure source. Along with efforts to reduce mercury in the general environment, food intake management should be undertaken to reduce the human exposure to methylmercury in Korea. PMID:23230465

  2. EFFECTS OF DIETARY METHYLMERCURY EXPOSURE ON AMERICAN KESTRELS

    EPA Science Inventory

    Several recent ecological risk assessments and criteria development efforts suggest that sensitive individuals of some piscivorous (fish eating) wildlife populations may be experiencing adverse effects from methylmercury exposure. The primary exposure route of methylmercury to t...

  3. Health risks from increases in methylmercury exposure.

    PubMed Central

    Mottet, N K; Shaw, C M; Burbacher, T M

    1985-01-01

    Our present knowledge of the human health effects of methylmercury exposure is derived from study of major outbreaks of human poisonings in Japan and Iraq and experimental studies on primates. Methylmercury readily passes through such physiological barriers as the blood-brain barrier, blood-testes barrier, and the placenta. Its major pathological effects are on the nervous and reproductive systems and the developing embryo/fetus. The neurotoxicity of methylmercury is well established in both humans and non-human primates. Lesions in the cerebral and cerebellar gray matter consist of necrosis and lysis of neurons, phagocytosis and gliosis. The changes are most prominent in the deep sulci and may have a vascular component. A late effect is cerebral atrophy. At high dose levels the liver, kidneys, and other organs may also have degenerative changes. Although not yet described in humans, a major effect of exposure of female primates is an adverse effect on pregnancy. Maternal female M. fascicularis blood mercury levels above 1 ppm are associated with a decreased pregnancy rate and increased abortion rate. To date our experimental data lack sufficient numbers to detect infrequent pregnancy effects below 1 ppm. Preliminary studies also reveal that methylmercury may also decrease the number and function (swim speed) of sperm. Both human and primate studies demonstrate deleterious effects of methylmercury on the developing embryo/fetus. Autopsies on human and primate infants reveal retarded brain development and the occurrence of a cerebral palsy-like behavior in the newborns, whereas the mother may be free of signs and symptoms of methylmercury toxicity. The fetal blood level of mercury is higher than the maternal level.(ABSTRACT TRUNCATED AT 250 WORDS) Images FIGURE 1. FIGURE 2. FIGURE 3. FIGURE 5. PMID:3908085

  4. Neurobehavioral effects of developmental methylmercury exposure.

    PubMed Central

    Gilbert, S G; Grant-Webster, K S

    1995-01-01

    Methylmercury (MeHg) is a global environmental problem and is listed by the International Program of Chemical Safety as one of the six most dangerous chemicals in the world's environment. Human exposure to MeHg primarily occurs through the consumption of contaminated food such as fish, although catastrophic exposures due to industrial pollution have occurred. The fetus is particularly sensitive to MeHg exposure and adverse effects on infant development have been associated with levels of exposure that result in few, if any, signs of maternal clinical illness or toxicity. High levels of prenatal exposure in humans result in neurobehavioral effects such as cerebral palsy and severe mental retardation. Prenatal exposure to MeHg in communities with chronic low-level exposure is related to decreased birthweight and early sensorimotor dysfunction such as delayed onset of walking. Neurobehavioral alterations have also been documented in studies with nonhuman primates and rodents. Available information on the developmental neurotoxic effects of MeHg, particularly the neurobehavioral effects, indicates that the fetus and infant are more sensitive to adverse effects of MeHg. It is therefore recommended that pregnant women and women of childbearing age be strongly advised to limit their exposure to potential sources of MeHg. Based on results from human and animal studies on the developmental neurotoxic effects of methylmercury, the accepted reference dose should be lowered to 0.025 to 0.06 MeHg microgram/kg/day. Continued research on the neurotoxic effects associated with low level developmental exposure is needed. PMID:8549462

  5. Neurobehavioral effects of developmental methylmercury exposure

    SciTech Connect

    Gilbert, S.G.; Grant-Webster, K.S.

    1995-09-01

    Methylmercury (MeHg) is a global environmental problem and is listed by the International Program of Chemical Safety as one of the six most dangerous chemicals in the world`s environment. Human exposure to MeHg primarily occurs through the consumption of contaminated food such as fish, although catastrophic exposures due to industrial pollution have occurred. The fetus is particularly sensitive to MeHg exposure and adverse effects on infant development have been associated with levels of exposure that result in few, if any, signs of maternal clinical illness or toxicity. High levels of prenatal exposure in humans result in neurobehavioral effects such as cerebral palsy and severe mental retardation. Prenatal exposure to MeHg in communities with chronic low-level exposure is related to decreased birthweight and early sensorimotor dysfunction such as delayed onset of walking. Neurobehavioral alterations have also been documented in studies with non human primates and rodents. Available information on the developmental neurotoxic effects of MeHg, particularly the neurobehavioral effects, indicates that the fetus and infant are more sensitive to adverse effects of MEHg. It is therefore recommended that pregnant women and women of childbearing age be strongly advised to limit their exposure to potential sources of MeHg. Based on results from human and animal studies on the developmental neurotoxic effects of methylmercury, the accepted reference dose should be lowered to 0.025 to 0.06 MeHg {mu}g/kg/day. Continued research on the neurotoxic effects associated with low level developmental exposure is needed. 107 refs., 3 tabs.

  6. Reducing uncertainty in risk modeling for methylmercury exposure

    SciTech Connect

    Ponce, R.; Egeland, G.; Middaugh, J.; Lee, R.

    1995-12-31

    The biomagnification and bioaccumulation of methylmercury in marine species represents a challenge for risk assessment related to the consumption of subsistence foods in Alaska. Because of the profound impact that food consumption advisories have on indigenous peoples seeking to preserve a way of life, there is a need to reduce uncertainty in risk assessment. Thus, research was initiated to reduce the uncertainty in assessing the health risks associated with the consumption of subsistence foods. Because marine subsistence foods typically contain elevated levels of methylmercury, preliminary research efforts have focused on methylmercury as the principal chemical of concern. Of particular interest are the antagonistic effects of selenium on methylmercury toxicity. Because of this antagonism, methylmercury exposure through the consumption of marine mammal meat (with high selenium) may not be as toxic as comparable exposures through other sources of dietary intake, such as in the contaminated bread episode of Iraq (containing relatively low selenium). This hypothesis is supported by animal experiments showing reduced toxicity of methylmercury associated with marine mammal meat, by the antagonistic influence of selenium on methylmercury toxicity, and by negative clinical findings in adult populations exposed to methylmercury through a marine diet not subject to industrial contamination. Exploratory model development is underway to identify potential improvements and applications of current deterministic and probabilistic models, particularly by incorporating selenium as an antagonist in risk modeling methods.

  7. Rice Methylmercury Exposure and Mitigation: A Comprehensive Review

    PubMed Central

    Rothenberg, Sarah E.; Windham-Myers, Lisamarie; Creswell, Joel E.

    2014-01-01

    Rice cultivation practices from field preparation to post-harvest transform rice paddies into hot spots for microbial mercury methylation, converting less-toxic inorganic mercury to more-toxic methylmercury, which is likely translocated to rice grain. This review includes 51 studies reporting rice total mercury and/or methylmercury concentrations, based on rice cultivated or purchased in 15 countries. Not surprisingly, both rice total mercury and methylmercury levels were significantly higher in polluted sites compared to non-polluted sites (Wilcoxon rank sum, p<0.001). However, rice percent methylmercury (of total mercury) did not differ statistically between polluted and non-polluted sites (Wilcoxon rank sum, p=0.35), suggesting comparable mercury methylation rates in paddy soil across these sites and/or similar accumulation of mercury species for these rice cultivars. Studies characterizing the effect of rice cultivation under more aerobic conditions were reviewed to determine the mitigation potential of this practice. Rice management practices utilizing alternating wetting and drying (instead of continuous flooding) caused soil methylmercury levels to spike, resulting in a strong methylmercury pulse after fields were dried and reflooded; however, it is uncertain whether this led to increased translocation of methylmercury from paddy soil to rice grain. Due to the potential health risks, it is advisable to investigate this issue further, and to develop separate water management strategies for mercury polluted and non-polluted sites, which minimize methylmercury exposure through rice ingestion. PMID:24972509

  8. Rice methylmercury exposure and mitigation: a comprehensive review

    USGS Publications Warehouse

    Rothenberg, Sarah E.; Windham-Myers, Lisamarie; Creswell, Joel E.

    2014-01-01

    Rice cultivation practices from field preparation to post-harvest transform rice paddies into hot spots for microbial mercury methylation, converting less-toxic inorganic mercury to more-toxic methylmercury, which is likely translocated to rice grain. This review includes 51 studies reporting rice total mercury and/or methylmercury concentrations, based on rice (Orzya sativa) cultivated or purchased in 15 countries. Not surprisingly, both rice total mercury and methylmercury levels were significantly higher in polluted sites compared to non-polluted sites (Wilcoxon rank sum, p<0.001). However, rice percent methylmercury (of total mercury) did not differ statistically between polluted and non-polluted sites (Wilcoxon rank sum, p=0.35), suggesting comparable mercury methylation rates in paddy soil across these sites and/or similar accumulation of mercury species for these rice cultivars. Studies characterizing the effects of rice cultivation under more aerobic conditions were reviewed to determine the mitigation potential of this practice. Rice management practices utilizing alternating wetting and drying (instead of continuous flooding) caused soil methylmercury levels to spike, resulting in a strong methylmercury pulse after fields were dried and reflooded; however, it is uncertain whether this led to increased translocation of methylmercury from paddy soil to rice grain. Due to the potential health risks, it is advisable to investigate this issue further, and to develop separate water management strategies for mercury polluted and non-polluted sites, in order to minimize methylmercury exposure through rice ingestion.

  9. Rice methylmercury exposure and mitigation: a comprehensive review.

    PubMed

    Rothenberg, Sarah E; Windham-Myers, Lisamarie; Creswell, Joel E

    2014-08-01

    Rice cultivation practices from field preparation to post-harvest transform rice paddies into hot spots for microbial mercury methylation, converting less-toxic inorganic mercury to more-toxic methylmercury, which is likely translocated to rice grain. This review includes 51 studies reporting rice total mercury and/or methylmercury concentrations, based on rice (Orzya sativa) cultivated or purchased in 15 countries. Not surprisingly, both rice total mercury and methylmercury levels were significantly higher in polluted sites compared to non-polluted sites (Wilcoxon rank sum, p<0.001). However, rice percent methylmercury (of total mercury) did not differ statistically between polluted and non-polluted sites (Wilcoxon rank sum, p=0.35), suggesting comparable mercury methylation rates in paddy soil across these sites and/or similar accumulation of mercury species for these rice cultivars. Studies characterizing the effects of rice cultivation under more aerobic conditions were reviewed to determine the mitigation potential of this practice. Rice management practices utilizing alternating wetting and drying (instead of continuous flooding) caused soil methylmercury levels to spike, resulting in a strong methylmercury pulse after fields were dried and reflooded; however, it is uncertain whether this led to increased translocation of methylmercury from paddy soil to rice grain. Due to the potential health risks, it is advisable to investigate this issue further, and to develop separate water management strategies for mercury polluted and non-polluted sites, in order to minimize methylmercury exposure through rice ingestion. PMID:24972509

  10. Neurological and neurocognitive functions from intrauterine methylmercury exposure.

    PubMed

    Yorifuji, Takashi; Kado, Yoko; Diez, Midory Higa; Kishikawa, Toshihiro; Sanada, Satoshi

    2016-05-01

    In the 1950s, large-scale food poisoning caused by methylmercury was identified in Minamata, Japan. Although severe intrauterine exposure cases (ie, congenital Minamata disease patients) are well known, possible impacts of methylmercury exposure in utero among residents, which is likely at lower levels than in congenital Minamata disease patients, are rarely explored. In 2014, the authors examined neurological and neurocognitive functions among 18 exposed participants in Minamata, focusing on fine motor, visuospatial construction, and executive functions. More than half of the participants had some fine motor and coordination difficulties. In addition, several participants had lower performance for neurocognitive function tests (the Rey-Osterrieth Complex Figure test and Keio version of the Wisconsin card sorting test). These deficits imply diffuse brain damage. This study suggests possible neurological and neurocognitive impacts of prenatal exposure to methylmercury among exposed residents of Minamata. PMID:26267674

  11. Monitoring methylmercury during pregnancy: maternal hair predicts fetal brain exposure.

    PubMed

    Cernichiari, E; Brewer, R; Myers, G J; Marsh, D O; Lapham, L W; Cox, C; Shamlaye, C F; Berlin, M; Davidson, P W; Clarkson, T W

    1995-01-01

    Autopsy brains were obtained from infants dying from a variety of causes within a few days of birth in a population exposed to methylmercury in fish. Infant and maternal blood and hair samples were also obtained. The concentration of total mercury in 6 major brain regions were highly correlated with maternal hair levels. This correlation was confirmed by a sequence of comparisons of maternal hair to maternal blood to infant blood and finally to infant brain. The results lend support to the use of maternal hair in assessing fetal exposure to methylmercury in fish-eating populations. PMID:8714874

  12. Human milk as a source of methylmercury exposure in infants

    SciTech Connect

    Grandjean, P. ); Jorgensen, P.J. ); Weihe, P. )

    1994-01-01

    As methylmercury is excreted in human milk and infants are particularly susceptible to toxicity due to this compound, the purpose of this study was to evaluate the possible transfer of methylmercury to infants via breast-feeding. In a community with a high intake of seafood, 583 children from a birth cohort were followed. The duration of nursing was recorded, and hair samples were obtained for mercury analysis at approximately 12 months of age. The hair mercury concentrations increased with the length of the nursing period, and those nursed throughout the first year showed the highest geometric mean (9.0 nmol/g or 1.8 [mu]g/g). Human milk therefore seems to be an important source of methylmercury exposure in infants. As increasing time interval from weaning to hair sample collection was not associated with any detectable decrease in mercury concentrations. A slow or absent elimination of methylmercury during the first year after birth could explain this finding. In certain fishing communities, infants nursed for long periods may be at increased risk of developing methylmercury toxicity. 25 refs., 2 figs., 3 tabs.

  13. Exposures of dental professionals to elemental mercury and methylmercury.

    PubMed

    Goodrich, Jaclyn M; Chou, Hwai-Nan; Gruninger, Stephen E; Franzblau, Alfred; Basu, Niladri

    2016-01-01

    Mercury (Hg) exposure, a worldwide public health concern, predominantly takes two forms--methylmercury from fish consumption and elemental Hg from dental amalgam restorations. We recruited 630 dental professionals from an American Dental Association meeting to assess Hg body burden and primary sources of exposure in a dually exposed population. Participants described occupational practices and fish consumption patterns via questionnaire. Hg levels in biomarkers of elemental Hg (urine) and methylmercury (hair and blood) were measured with a Direct Mercury Analyzer-80 and were higher than the general US population. Geometric means (95% CI) were 1.28 (1.19-1.37) μg/l in urine, 0.60 (0.54-0.67) μg/g in hair and 3.67 (3.38-3.98) μg/l in blood. In multivariable linear regression, personal amalgams predicted urine Hg levels along with total years in dentistry, amalgams handled, working hours and sex. Fish consumption patterns predicted hair and blood Hg levels, which were higher among Asians compared with Caucasians. Five species contributed the majority of the estimated Hg intake from fish--swordfish, fresh tuna, white canned tuna, whitefish and king mackerel. When studying populations with occupational exposure to Hg, it is important to assess environmental exposures to both elemental Hg and methylmercury as these constitute a large proportion of total exposure. PMID:26329138

  14. FUNCTIONAL CONSEQUENCES OF PRENATAL METHYLMERCURY EXPOSURE: EFFECTS ON RENAL AND HEPATIC RESPONSES TO TROPHIC STIMULI AND ON RENAL EXCRETORY MECHANISMS

    EPA Science Inventory

    The effects of prenatal exposure to methylmercury on the functional development of renal and hepatic response systems was examined in the developing rat. Methylmercury produced an elevation of basal activity of renal ornithine decarboxylase (ODC, an enzyme involved in regulation ...

  15. Assessing sources of human methylmercury exposure using stable mercury isotopes.

    PubMed

    Li, Miling; Sherman, Laura S; Blum, Joel D; Grandjean, Philippe; Mikkelsen, Bjarni; Weihe, Pál; Sunderland, Elsie M; Shine, James P

    2014-01-01

    Seafood consumption is the primary route of methylmercury (MeHg) exposure for most populations. Inherent uncertainties in dietary survey data point to the need for an empirical tool to confirm exposure sources. We therefore explore the utility of Hg stable isotope ratios in human hair as a new method for discerning MeHg exposure sources. We characterized Hg isotope fractionation between humans and their diets using hair samples from Faroese whalers exposed to MeHg predominantly from pilot whales. We observed an increase of 1.75‰ in δ(202)Hg values between pilot whale muscle tissue and Faroese whalers' hair but no mass-independent fractionation. We found a similar offset in δ(202)Hg between consumed seafood and hair samples from Gulf of Mexico recreational anglers who are exposed to lower levels of MeHg from a variety of seafood sources. An isotope mixing model was used to estimate individual MeHg exposure sources and confirmed that both Δ(199)Hg and δ(202)Hg values in human hair can help identify dietary MeHg sources. Variability in isotopic signatures among coastal fish consumers in the Gulf of Mexico likely reflects both differences in environmental sources of MeHg to coastal fish and uncertainty in dietary recall data. Additional data are needed to fully refine this approach for individuals with complex seafood consumption patterns. PMID:24967674

  16. Human exposure to methylmercury from crayfish (Procambarus clarkii) in China.

    PubMed

    Peng, Qian; Greenfield, Ben K; Dang, Fei; Zhong, Huan

    2016-02-01

    Methylmercury (MeHg) accumulation in aquatic food raises global concerns about human exposure to MeHg. Crayfish is the world's third largest farmed crustacean species and a favorite aquatic food in many countries. However, human health hazard due to MeHg exposure via crayfish consumption is unclear, partly because appropriate survey data are lacking. We report on mercury concentrations and speciation in edible tail muscle of crayfish collected from restaurants in 23 Chinese cities. On average, MeHg constituted 99.1 % of mercury in tail muscle, and MeHg concentrations were comparable with those reported for fish in China. Variation in MeHg concentrations was not attributable to broad geographic region (i.e., provinces) or tail length. For different populations, potential health risk (characterized by hazard quotient or HQ) of MeHg exposure through crayfish consumption depended largely on crayfish consumption rates. In particular, a health hazard (HQ > 1) was found for high-rate consumers (i.e., 95 %ile or higher) in some cities in the middle and lower reaches of the Yangtze River (MLYR), during the peak consumption season. Our results suggest that more attention should be paid to dietary MeHg intake via crayfish consumption in China, particularly for communities with high consumption in MLYR. PMID:25850898

  17. Developmental selenomethionine and methylmercury exposures affect zebrafish learning

    PubMed Central

    Smith, Leigh E.; Carvan, Michael J.; Dellinger, John A.; Ghorai, Jugal K.; White, Donald B.; Williams, Frederick E.; Weber, Daniel N.

    2009-01-01

    Methylmercury (MeHg) is a ubiquitous environmental pollutant and has been shown to affect learning in vertebrates following relatively low exposures. Zebrafish were used to model long-term learning deficits after developmental MeHg exposure. Selenomethionine (SeMet) co-exposure was used to evaluate its role in neuroprotection. Embryos were exposed from 2–24 hours post fertilization to (1) MeHg without SeMet, (2) SeMet without MeHg and (3) in combination of MeHg and SeMet. In case (1), the levels of MeHg were 0.00, 0.01, 0.03, 0.06, 0.10, 0.30 µM. In case (2), the levels of SeMet were 0.00. 0.03, 0.06, 0.10, 0.30 µM. In case (3), co-exposure levels of (MeHg, SeMet) were (0.03, 0.03), (0.03, 0.06), (0.03, 0.10), (0.03, 0.30), (0.10, 0.03), (0.10, 0.06), (0.10, 0.10), (0.10, 0.30) µM. Learning functions were tested in individual adults, four months after developmental exposure using a spatial alternation paradigm with food delivery on alternating sides of the aquarium. Low levels of MeHg (<0.1 µM) exposure delayed learning in treated fish; fish exposed to higher MeHg levels were unable to learn the task; SeMet co-exposure did not prevent this deficit. These data are consistent with findings in laboratory rodents. The dorsal and lateral telencephalon are the primary brain regions in fish involved in spatial learning and memory. Adult telencephalon cell body density decreased significantly at all MeHg exposures >0.01 µM MeHg. SeMet co-exposure ameliorated but did not prevent changes in telencephalon cell body density. In summary, MeHg affected both learning and brain structure, but SeMet only partially reversed the latter. PMID:19800969

  18. Selenomethionine reduces visual deficits due to developmental methylmercury exposures

    PubMed Central

    Weber, Daniel N.; Connaughton, Victoria P.; Dellinger, John A.; Klemer, David; Udvadia, Ava; Carvan, Michael J.

    2008-01-01

    Developmental exposures to methylmercury (MeHg) have life-long behavioral effects. Many micronutrients, including selenium, are involved in cellular defenses against oxidative stress and may reduce the severity of MeHg-induced deficits. Zebrafish embryos (<4 hours post fertilization, hpf) were exposed to combinations of 0.0-0.30 μM MeHg and/or selenomethionine (SeMet) until 24 hpf then placed in clean medium. Fish were tested as adults under low light conditions (~60 μW/m2) for visual responses to a rotating black bar. Dose-dependent responses to MeHg exposure were evident (ANOVA, P<0.001) as evidenced by reduced responsiveness, whereas SeMet did not induce deficits except at 0.3 μM,. Ratios of SeMet:MeHg of 1:1 or 1:3 resulted in responses that were indistinguishable from controls (ANOVA, P<0.001). No gross histopathologies were observed (H&E stain) in the retina or optic tectum at any MeHg concentration. Whole-cell, voltage-gated, depolarization-elicited outward K+ currents of bipolar cells in intact retina of slices adult zebrafish were recorded and outward K+ current amplitude was larger in bipolar cells of MeHg-treated fish. This was due to the intense response of cells expressing the delayed rectifying IK current; cells expressing the transient IA current displayed a slight trend for smaller amplitude among MeHg-treated fish. Developmental co-exposure to SeMet reduced but did not eliminate the increase in the MeHg-induced IK response, however, IA responses increased significantly over MeHg-treated fish to match control levels. Electrophysiological deficits parallel behavioral patterns in MeHg-treated fish, i.e., initial reactions to the rotating bar were followed by periods of inactivity and then a resumption of responses. PMID:17905328

  19. Country-specific estimates of the incidence of intellectual disability associated with prenatal exposure to methylmercury.

    PubMed

    Bellinger, David C; O'Leary, Keri; Rainis, Holly; Gibb, Herman J

    2016-05-01

    This paper describes country-specific estimates of the incidence of intellectual disability in children associated with prenatal exposure to methylmercury. A systematic review was undertaken to identify country-specific data on hair mercury concentrations in women of reproductive age. A variety of approaches were used to estimate biomarker concentrations for countries lacking such data. A dose-effect relationship derived on the basis of the data from three large prospective studies relating prenatal methylmercury exposure to IQ in children was used to estimate the country-specific incidences of mild, moderate, severe, and profound intellectual disability in children as a result of prenatal methylmercury exposure. The incidence of methylmercury-associated mild intellectual disability (IQ scores 50-70) varied nearly 40-fold across countries, with the greatest incidences generally in countries that are islands or that are coastal. Countries with high birth rates and greater consumption of foods that contribute most to methylmercury intake in humans (seafood, rice) can be expected to make the largest contributions to the worldwide burden of disease associated with methylmercury. The assumptions and limitations of the estimates are discussed. PMID:26874048

  20. [Methylmercury exposure in the general population; toxicokinetics; differences by gender, nutritional and genetic factors].

    PubMed

    González-Estecha, Montserrat; Bodas-Pinedo, Andrés; Guillén-Pérez, José Jesús; Rubio-Herrera, Miguel Ángel; Ordóñez-Iriarte, José M; Trasobares-Iglesias, Elena M; Martell-Claros, Nieves; Martínez-Álvarez, Jesús Román; Farré-Rovira, Rosaura; Herráiz-Martínez, Miguel Ángel; Martínez-Astorquiza, Txantón; Calvo-Manuel, Elpidio; Sáinz-Martín, María; Bretón-Lesmes, Irene; Prieto-Menchero, Santiago; Llorente-Ballesteros, M Teresa; Martínez-García, M José; Salas-Salvadó, Jordi; Bermejo-Barrera, Pilar; García-Donaire, José Antonio; Cuadrado-Cenzual, M Ángeles; Gallardo-Pino, Carmen; Moreno-Rojas, Rafael; Arroyo-Fernández, Manuel; Calle-Pascual, Alfonso

    2014-01-01

    Mercury is an environmental toxicant that causes numerous adverse effects on human health and natural ecosystems. The factors that determine the existance of adverse effects, as well as their severity are, among others: the chemical form of mercury (elemental, inorganic, organic), dosis, age, period of exposure, pathways of exposure and environmental, nutritional and genetic factors. In the aquatic cycle of mercury, once it has been deposited, it is transformed into methylmercury due to the action of certain sulphate-reducing bacteria, which bioaccumulates in the aquatic organisms and moves into the food chain. The methylmercury content of large, long-lived fish such as swordfish, shark, tuna or marlin, is higher. Methylmercury binds to protein in fish and is therefore not eliminated by cleaning or cooking the fish. Fetuses and small children are more vulnerable to the neurotoxic effects of methylmercury from the consumption of contaminated fish. Methylmercury is absorbed in the gastrointestinal tract and crosses the blood-brain barrier and the placenta. The intake of certain dietary components such as polyunsaturated fatty acids, selenium, fiber, thiol compounds, certain phytochemicals and other nutrients can modify methylmercury bioaccesibility and its toxicity. Apart from environmental factors, genetic factors can influence mercury toxicity and explain part of the individual vulnerability. PMID:25365001

  1. [Fish and seafood as a source of human exposure to methylmercury].

    PubMed

    Mania, Monika; Wojciechowska-Mazurek, Maria; Starska, Krystyna; Rebeniak, Małgorzata; Postupolski, Jacek

    2012-01-01

    Fish and seafood are recommended diet constituents providing high quality protein, vitamins, minerals and omega-3 fatty acids, mainly eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). However, these foodstuffs can also be the major source ofmethylmercury intake in humans. In general, more than 90% of the mercury in fish is found as methylmercury, but contents of methylmercury can vary considerably between species. Predatory species that are at the top of the food chain and live a long time, may accumulate higher levels of methylmercury. This paper contains information about sources of human exposure to organic compounds of mercury, toxicity, metabolism and transformation of mercury in the environment. Assessment of methylmercury by international risk assessment bodies such as the Joint FAO/WHO Expert Committee on Food Additives (JECFA) and U.S. National Research Council (NRC) were presented. Climate changes and their influence on the mercury cycle in the environment especially mercury methylation and concentrations of methylmercury in marine species were also presented. Consumer advice prepared by European Commission and Member States as regards consumption of predatory fishes such as swordfish, tuna, shark, marlin and pike, taking into account the most vulnerable groups of population e.g. women planning pregnancy, pregnant or breastfeeding women and children were presented. Mercury and methylmercury contamination of fishes and seafood on the basis of the literature references as well as intake of mercury with fish and fish products in Poland and other European country were discussed. The role of selenium as a factor which counteracts methylmercury toxicity and protects against some neurological effects of methylmercury exposure in humans, as well as information on potential etiological factors connected with autism disorder were also described. Attention has also been drawn to increasing number of notifications to Rapid Alert System for Food and Feed

  2. EFFECTS OF NEONATAL METHYLMERCURY EXPOSURE ON ADRENERGIC RECEPTOR BINDING SITES IN PERIPHERAL TISSUES OF THE DEVELOPING RAT

    EPA Science Inventory

    Neonatal exposure to methylmercury produces changes in patterns of tissue growth and function, in part, due to alterations in adrenergic neuronal input. To explore the mechanisms by which these changes come about, newborn rats were exposed to methylmercury (1 or 2.5 mg/kg/day) th...

  3. Patterns and Consequences of in ovo Exposure to Methylmercury in Common Loons, poster presentation

    EPA Science Inventory

    A critical component of a common loon/mercury (Hg) risk assessment model under development is the determination of the concentration of Hg in eggs that poses a population level risk. We conducted a field study to (1) characterize in ovo methylmercury (MeHg) exposure in Wisconsin...

  4. [Consensus document on the prevention of exposure to methylmercury in Spain].

    PubMed

    González-Estecha, Montserrat; Bodas-Pinedo, Andrés; Guillén-Pérez, José Jesús; Rubio-Herrera, Miguel Ángel; Martínez-Álvarez, Jesús Román; Herráiz-Martínez, Miguel Ángel; Martell-Claros, Nieves; Ordóñez-Iriarte, José M; Sáinz-Martín, María; Farré-Rovira, Rosaura; Martínez-Astorquiza, Txantón; García-Donaire, José Antonio; Calvo-Manuel, Elpidio; Bretón-Lesmes, Irene; Prieto-Menchero, Santiago; Llorente-Ballesteros, M Teresa; Martínez-García, M José; Moreno-Rojas, Rafael; Salas-Salvadó, Jordi; Bermejo-Barrera, Pilar; Cuadrado-Cenzual, María Ángeles; Gallardo-Pino, Carmen; Blanco Fuentes, María; Torres-Moreno, Miriam; Trasobares-Iglesias, Elena M; Barceló Martín, Bernardino; Arroyo-Fernández, Manuel; Calle-Pascual, Alfonso

    2015-01-01

    The beneficial effects of fish consumption in both children and adults are well known. However, the intake of methylmercury, mainly from contaminated fish and shellfish, can have adverse health effects. The study group on the prevention of exposure to methylmercury (GEPREM-Hg), made up of representatives from different Spanish scientific societies, has prepared a consensus document in a question and answer format, containing the group's main conclusions, recommendations and proposals. The objective of the document is to provide broader knowledge of factors associated with methylmercury exposure, its possible effects on health among the Spanish population, methods of analysis, interpretation of the results and economic costs, and to then set recommendations for fish and shellfish consumption. The group sees the merit of all initiatives aimed at reducing or prohibiting the use of mercury as well as the need to be aware of the results of contaminant analyses performed on fish and shellfish marketed in Spain. In addition, the group believes that biomonitoring systems should be set up in order to follow the evolution of methylmercury exposure in children and adults and perform studies designed to learn more about the possible health effects of concentrations found in the Spanish population, ta king into account the lifestyle, eating patterns and the Mediterranean diet. PMID:25561095

  5. Methylmercury content of eggs in yellow perch related to maternal exposure in four Wisconsin lakes

    SciTech Connect

    Hammerschmidt, C.R.; Frazier, B.E.; Rada, R.G.; Wiener, J.G.

    1999-04-01

    The authors examined the influence of maternal mercury and selected lacustrine variables on the mercury content of eggs from yellow perch (Perca flavescens). Total mercury, methylmercury, and inorganic mercury were determined in eggs and carcasses (less eggs) from three seepage lakes with a pH range of 6.1--7.0 and a fourth lake in which pH was experimentally increased from 5.5 to 6.8 by addition of alkaline groundwater. The concentration of total mercury in eggs was strongly correlated with that in the material carcass. Concentrations and burdens of mercury in eggs and carcasses were inversely correlated with lake water pH, acid-neutralizing capacity, calcium, and dissolved organic carbon. In eggs containing more than 30 ng/g dry weight of total mercury, methylmercury averaged 91% of total mercury and ranged from 85% to 96%. Mean burdens of total mercury in individual eggs varied greatly among lakes and the egg mass averaged 1.9% of the whole-body burden. The authors conclude that exposure of the developing yellow perch embryo to methylmercury is strongly affected by maternal bioaccumulation, which can vary substantially among and within lakes; however, the toxicological significance of the observed exposure of embryos to methylmercury is unclear.

  6. Methylmercury content of eggs in yellow perch related to maternal exposure in four Wisconsin lakes

    USGS Publications Warehouse

    Hammerschmidt, Chad R.; Wiener, James G.; Frazier, Brdaley E.; Rada, Ronald G.

    1999-01-01

    We examined the influence of maternal mercury and selected lacustrine variables on the mercury content of eggs from yellow perch (Perca flavescens). Total mercury, methylmercury, and inorganic mercury were determined in eggs and carcasses (less eggs) from three seepage lakes with a pH range of 6.1a??7.0 and a fourth lake in which pH was experimentally increased from 5.5 to 6.8 by addition of alkaline groundwater. The concentration of total mercury in eggs was strongly correlated with that in the maternal carcass. Concentrations and burdens of mercury in eggs and carcasses were inversely correlated with lake water pH, acid-neutralizing capacity, calcium, and dissolved organic carbon. In eggs containing more than 30 ng/g dry weight (4.5 ng/g wet weight) of total mercury, methylmercury averaged 91% of total mercury and ranged from 85% to 96%. Mean burdens of total mercury in individual eggs varied greatly among lakes (range, 2.3a??63 pg), and the egg mass averaged 1.9% of the whole-body burden. We conclude that exposure of the developing yellow perch embryo to methylmercury is strongly affected by maternal bioaccumulation, which can vary substantially among and within lakes; however, the toxicological significance of the observed exposure of embryos to methylmercury is unclear.

  7. Perinatal and lifetime exposure to methylmercury in the mouse: behavioral effects.

    PubMed

    Weiss, Bernard; Stern, Sander; Cox, Christopher; Balys, Marlene

    2005-08-01

    This project was undertaken to more completely understand the consequences of lifetime exposure to methylmercury. A series of experiments examined how perinatal or lifetime exposure to methylmercury affected behavioral performances in the adult mouse at different ages. One hundred female B6C3F1/HSD mice were assigned to one of three dose groups, 0 ppm, 1 ppm, or 3 ppm methylmercury chloride administered in a 5 nM sodium carbonate drinking solution. Four weeks after initiating dosing, the females were bred with male CBA/J HSD mice to produce the trihybrid offspring B6C3F1/HSD x CBA/J HSD. The methylmercury-treated litters were split into two subgroups, one exposed throughout its lifetime to the original dose, the other exposed through postnatal day 13. Altogether, then, five groups were studied: Control, 1 ppm perinatal, 1 ppm lifetime, 3 ppm perinatal, and 3 ppm lifetime. Three neurobehavioral indices were evaluated: (1) delayed spatial alternation (a test of memory) and (2) running in a wheel to earn food pellets (schedule-controlled operant behavior) were assessed starting at 5 and 15 months of age; (3) hindlimb splay, a measure of motor function, was assessed at 5, 15, and 26 months of age. Subjects tested at one age were littermates of those tested at the other ages. MeHg altered the hindlimb splay distance; control mice differed from methylmercury-exposed mice, the 1 ppm lifetime and 3 ppm lifetime groups differed from each other, and the analysis yielded an age by dose interaction. MeHg exposure altered different measures of wheel running under the 3 ppm lifetime condition. In the delayed alternation procedure, the mouse was required to respond to one of two locations in a strictly alternating sequence. More mice from the treated groups, except for the 1 ppm perinatal group, failed to meet the criterion at longer delay values. Overall, the results show that exposure to low levels of methylmercury produces behavioral effects that depend on the test procedure

  8. Functional consequences of prenatal methylmercury exposure: effects on renal and hepatic responses to trophic stimuli and on renal excretory mechanisms

    SciTech Connect

    Slotkin, T.A.; Kavlock, R.J.; Cowdery, T.; Orband, L.; Bartolome, M.

    1986-01-01

    The effects of prenatal exposure to methylmercury on the functional development of renal and hepatic response systems was examined in the developing rat. Methylmercury produced an elevation of basal activity of renal ornithine decarboxylase (ODC, an enzyme involved in regulation of cellular maturation) and an eventual relative hypertrophy; liver ODC was reduced and hypertrophy was not evident. In contrast, the reactivity of liver ODC to trophic stimulants (vasopressin, isoproterenol) was markedly enhanced by prenatal methylmercury exposure, whereas renal ODC responses were much less affected (vasopressin) or actually reduced (isoproterenol). Targeted actions of methylmercury on renal excretory function were also prominent, with increased fractional excretions urea and electrolytes and an eventual reduction in glomerular filtration as assessed by creatinine clearance. These studies show that doses of methylmercury ordinarily associated with selective actions on development of neurobehavioral patterns also influence the functional ontogeny of other organ systems; furthermore, the fact that the target tissues are different for prenatal vs postnatal methylmercury exposure, indicates that the functional teratology of methylmercury exhibits critical periods of sensitivity.

  9. Relation of Prenatal Methylmercury Exposure from Environmental Sources to Childhood IQ

    PubMed Central

    Muckle, Gina; Ayotte, Pierre; Dewailly, Éric

    2015-01-01

    Background Although prenatal methylmercury exposure has been linked to poorer intellectual function in several studies, data from two major prospective, longitudinal studies yielded contradictory results. Associations with cognitive deficits were reported in a Faroe Islands cohort, but few were found in a study in the Seychelles Islands. It has been suggested that co-exposure to another contaminant, polychlorinated biphenyls (PCBs), may be responsible for the positive findings in the former study and that co-exposure to nutrients in methylmercury-contaminated fish may have obscured and/or protected against adverse effects in the latter. Objectives We aimed to determine the degree to which co-exposure to PCBs may account for the adverse effects of methylmercury and the degree to which co-exposure to docosahexaenoic acid (DHA) may obscure these effects in a sample of Inuit children in Arctic Québec. Methods IQ was estimated in 282 school-age children from whom umbilical cord blood samples had been obtained and analyzed for mercury and other environmental exposures. Results Prenatal mercury exposure was related to poorer estimated IQ after adjustment for potential confounding variables. The entry of DHA into the model significantly strengthened the association with mercury, supporting the hypothesis that beneficial effects from DHA intake can obscure adverse effects of mercury exposure. Children with cord mercury ≥ 7.5 μg/L were four times as likely to have an IQ score < 80, the clinical cut-off for borderline intellectual disability. Co-exposure to PCBs did not alter the association of mercury with IQ. Conclusions To our knowledge, this is the first study to document an association of prenatal mercury exposure with poorer performance on a school-age assessment of IQ, a measure whose relevance for occupational success in adulthood is well established. This association was seen at levels in the range within which many U.S. children of Asian-American background are

  10. Fetal and maternal immune responses to methylmercury exposure: a cross-sectional study.

    PubMed

    Nyland, Jennifer F; Wang, Susie B; Shirley, Devon L; Santos, Elisabeth O; Ventura, Ana Maria; de Souza, Jose M; Silbergeld, Ellen K

    2011-05-01

    Methylmercury (MeHg) is a ubiquitous environmental contaminant with known neurodevelopmental effects. In humans, prenatal exposures primarily occur through maternal consumption of contaminated fish. In this study, we evaluated the association between prenatal exposure to MeHg and titers of total immunoglobulins (Ig) and specific autoantibodies in both mothers and fetuses by analyzing maternal and cord blood serum samples. We examined multiple immunoglobulin isotypes to determine if these biomarkers could inform as to fetal or maternal responses since IgG but not IgM can cross the placenta. Finally, we evaluated serum cytokine levels to further characterize the immune response to mercury exposure. The study was conducted using a subset of serum samples (N=61 pairs) collected from individuals enrolled in a population surveillance of MeHg exposures in the Brazilian Amazon during 2000/2001. Serum titers of antinuclear and antinucleolar autoantibodies were measured by indirect immunofluorescence. Serum immunoglobulins were measured by enzyme-linked immunosorbent assay (ELISA) and BioPlex multiplex assay. Serum cytokines were measured by BioPlex multiplex assay. In this population, the geometric mean mercury level was within the 95th percentile for US populations of women of childbearing age but the upper level of the range was significantly higher. Fetal blood mercury levels were higher (1.35 times) than those in their mothers, but highly correlated (correlation coefficient [r]=0.71; 95% CI: 0.54, 0.89). Total IgG (r=0.40; 95% CI: 0.19, 0.62) and antinuclear autoantibody (odds ratio [OR]=1.05; 95% CI: 1.02, 1.08) levels in paired maternal and fetal samples were also associated; in contrast, other immunoglobulin (IgM, IgE, and IgA) levels were not associated between pairs. Total IgG levels were significantly correlated with both maternal (r=0.60; 95% CI: 0.25, 0.96) and cord blood mercury levels (r=0.61; 95% CI: 0.25, 0.97), but individual isotypes were not. Serum

  11. Short-term effect of severe exposure to methylmercury on atherosclerotic heart disease and hypertension mortality in Minamata.

    PubMed

    Inoue, Sachiko; Yorifuji, Takashi; Tsuda, Toshihide; Doi, Hiroyuki

    2012-02-15

    Recent studies suggest potential adverse effects of methylmercury exposure on myocardial infarction and hypertension, although the evidence is still limited. We thus evaluated this association using age-standardized mortality ratios (ASMRs) in Minamata, where severe methylmercury poisoning had occurred. We obtained mortality data from annual vital statistics and demographic statistics from census. We then compared mortality of atherosclerotic heart disease including degenerative heart disease and hypertension in Minamata-city with those in Kumamoto Prefecture, which includes Minamata city, as a control. We estimated ASMRs and 95% confidence intervals (CIs) during the period from 1953 to 1970. ASMRs of atherosclerotic heart disease were continuously decreased during the period from 1953 to 1967. In contrast, the ASMR of hypertension was significantly elevated during the period from 1963 to 1967 (SMR=1.38, CI; 1.06-1.80); but they decreased later. Although dilution is present in this ecological study, our study supports the notion that methylmercury exposure induces hypertension. PMID:22277149

  12. Effects of early life exposure to methylmercury in Daphnia pulex on standard and reduced food ration

    PubMed Central

    Doke, Dzigbodi A.; Hudson, Sherri L.; Dawson, John A.; Gohlke, Julia M.

    2015-01-01

    As a well-known eco-toxicological model organism, Daphnia pulex may also offer advantages in human health research for assessing long-term effects of early life exposures to coupled stressors. Here, we examine consequences of early life exposure to methylmercury (MeHg) under standard and reduced food ration. We exposed Daphnia for 24 h in early life to varying concentrations of methylmercury(II) chloride (0, 200, 400, 800 and 1600 ng/L) and thereafter kept Daphnia on either a standard or a reduced food ration. The data suggests an additive effect of MeHg concentration and food ration on decreasing lifespan, although MeHg concentration does not affect survival linearly. Food ration and MeHg concentration were predictive of reduced reproduction, and there is some evidence of an interaction (p = 0.048). Multi-stressor work in alternative model systems may be useful for prioritizing research, taking into account potential antagonistic, additive or synergistic effects that nutritional status may have on chemical toxicity. PMID:25263226

  13. EFFECTS OF NEONATAL METHYLMERCURY EXPOSURE ON DEVELOPMENT OF NUCLEIC ACIDS AND PROTEINS IN RAT BRAIN: REGIONAL SPECIFICITY

    EPA Science Inventory

    Exposure of neonatal rats to methylmercury (1 or 2.5 mg/kg SC daily) during the preweaning period caused regionally-specific alterations in DNA, RNA and protein content in brain. In midbrain + brainstem, where neuronal replication and differentiation conclude early, reduced DNA c...

  14. Effects of neonatal methylmercury exposure on adrenergic-receptor binding sites in peripheral tissues of the developing rat

    SciTech Connect

    Slotkin, T.A.; Kavlock, R.J.; Cowdery, T.; Orband, L.; Bartolome, M.

    1986-01-01

    Neonatal exposure to methylmercury produces changes in patterns of tissue growth and function, in part, due to alterations in adrenergic neuronal input. To explore the mechanisms by which these changes come about, newborn rats were exposed to methylmercury (1 or 2.5 mg/kg/day) throughout the preweaning stage and the ontogeny of adrenergic receptor binding sites evaluated in liver, kidney, heart and lung, using (/sup 3/H)prazosin (alpha 1-receptors), (/sup 3/H)rauwolscine (alpha 2-receptors) and (/sup 125/I)pindolol (beta-receptors). In the kidney, methylmercury caused decreases in beta- and alpha 1-receptor binding and increases in alpha 2-binding, and the alterations persisted into adulthood; previous work has shown that beta-receptor-mediated responses are generally enhanced in methylmercury-exposed pups, and the down-regulation of beta-receptor binding thus probably represents a compensatory action secondary to alterations in post-receptor coupling mechanisms. The effects of methylmercury on hepatic adrenergic receptors were different from those seen in the kidney, with substantial elevations in beta- and alpha-receptor binding apparent in the preweaning stage; this agrees also with the differences in effects of the mercurial on trophic reactivity and growth in the two tissues.

  15. Re-evaluation of the reference dose for methylmercury and assessment of current exposure levels

    SciTech Connect

    Stern, A.H. )

    1993-06-01

    Methylmercury (Me-Hg) is widely distributed through freshwater and saltwater food chains and human consumption of fish and shellfish has lead to widespread exposure. Both the US EPA Reference Dose (0.3 [mu]g/kg/day) and the FAO/WHO Permissible Tolerable Weekly Intake (3.3 [mu]g/kg/week) are currently based on the prevention of paraesthesia in adult and older children. However, Me-Hg exposure in utero is known to result in a range of developmental neurologic effects including clinical CNS symptoms and delayed onset of walking. Based on a critical review of development toxicity data from human and animal studies, it is concluded that current guidelines for the prevention of paraesthesia are not adequate to address developmental effects. A dose of 0.07 [mu]g/kg/day is suggested as the best estimate of a potential reference dose for developmental effects. Data on nationwide fish consumption rates and Me-Hg levels in fish/seafood weighted by proportion of the catch intended for human consumption are analyzed in a Monte Carlo simulation to derive a probability distribution of background Me-Hg exposure. While various uncertainties in the toxicologic and exposure data limit the precision with which health risk can be estimated, this analysis suggests that at current levels of Me-Hg exposure, a significant fraction of women of childbearing age have exposures above this suggested reference dose.

  16. Effects of methylmercury and alcohol exposure in Drosophila melanogaster: Potential risks in neurodevelopmental disorders.

    PubMed

    Chauhan, Ved; Chauhan, Abha

    2016-06-01

    Extensive evidence suggests the role of oxidative stress in autism and other neurodevelopmental disorders. In this study, we investigated whether methylmercury (MeHg) and/or alcohol exposure has deleterious effects in Drosophila melanogaster (fruit flies). A diet containing different concentrations of MeHg in Drosophila induced free radical generation and increased lipid peroxidation (markers of oxidative stress) in a dose-dependent manner. This effect of MeHg on oxidative stress was enhanced by further exposure to alcohol. It was observed that alcohol alone could also induce free radical generation in flies. After alcohol exposure, MeHg did not affect the immobilization of flies, but it increased the recovery time in a concentration-dependent manner. MeHg significantly inhibited the activity of alcohol dehydrogenase (ADH) in a dose-dependent manner. Linear regression analysis showed a significant negative correlation between ADH activity and recovery time upon alcohol exposure in the flies fed a diet with MeHg. This relationship between ADH activity and recovery time after alcohol exposure was confirmed by adding 4-methyl pyrazole (an inhibitor of ADH) to the diet for the flies. These results suggest that consumption of alcohol by pregnant mothers who are exposed to MeHg may lead to increased oxidative stress and to increased length of time for alcohol clearance, which may have a direct impact on the development of the fetus, thereby increasing the risk of neurodevelopmental disorders. PMID:27151262

  17. The effect of a low iron diet and early life methylmercury exposure in Daphnia pulex.

    PubMed

    Hudson, Sherri L; Doke, Dzigbodi A; Gohlke, Julia M

    2016-03-01

    Iron (Fe) deficiency increases risk for adverse health outcomes in humans; however little is known about the potential interaction with methylmercury (MeHg) exposure. Studies testing multiple stressor hypotheses are expensive and time consuming in mammalian model systems; therefore, determining relevance of alternative models is important. Daphnia pulex were fed standard or low-Fe diets of freshwater algae, Ankistrodesmus falcatus. MeHgCl (1600 ng/L) or vehicle was added to culture media for 24 h during early life, and the combinatorial effects of a low-Fe diet and MeHg exposure on lifespan, maturation time, and reproduction were evaluated. Lipid storage effects were measured using image analysis of Oil Red O staining and triacylglyceride quantification. Our results show a dose-dependent reduction in lifespan in D. pulex fed low Fe diets. Lipid analysis suggests an interactive effect of diet and MeHg exposure, with MeHg exposure increasing lipid storage in D. pulex fed a low-Fe diet. These findings suggest the effects of dietary iron intake and early life MeHg exposure in D. pulex may be mediated by changes in energetics that result in differential lipid storage. Therefore, lipid storage in D. pulex may be a useful screen for detecting long-term effects of multiple stressors early in life. PMID:26806633

  18. Elevated prenatal methylmercury exposure in Nigeria: evidence from maternal and cord blood.

    PubMed

    Obi, Ejeatuluchukwu; Okafor, Charles; Igwebe, Anthony; Ebenebe, Joy; Afonne, Onyenmechi Johnson; Ifediata, Francis; Orisakwe, Orish Ebere; Nriagu, Jerome O; Basu, Niladri

    2015-01-01

    Methylmercury is a neurodevelopmental toxicant that is globally distributed though little is known about prenatal exposures in sub-Saharan Africa. The objective of the current study was to measure total mercury levels in cord blood and maternal blood from 95 mother-newborn pairs recruited from hospitals in Nnewi, Nigeria. The secondary aims of the study were to explore if demographic and dietary factors were associated with blood mercury levels, and to explore if mercury levels were associated with any self-reported health outcome and childbirth outcome. Maternal blood mercury levels averaged 3.6 μg L(-1) and ranged from 1.1 μg L(-1) to 9.5 μg L(-1). Cord blood mercury averaged 5.1 μg L(-1) and ranged from 1.2 μg L(-1) to 10.6 μg L(-1). The mean ratio of mercury in paired cord blood to maternal blood was 1.5 and it ranged from 0.4 to 3.2. Mercury in maternal and cord blood were significantly correlated (r=0.471). More than one-third of mothers reported eating fish at least once per day, and a weak (p=0.08) fish consumption-related increase in blood mercury was found. Cord blood mercury was positively and significantly associated with birth weight and length, and head and chest circumference. Mercury levels in 36% of the participants exceeded the biomonitoring guideline associated with the United States Environmental Protection Agency (U.S. EPA) reference dose for mercury. The study shows that pregnant women and their newborns are exposed to methylmercury and that their exposures are higher compared to general populations sampled from other regions of the world. PMID:25112573

  19. Gene expression changes in female zebrafish (Danio rerio) brain in response to acute exposure to methylmercury

    USGS Publications Warehouse

    Richter, Catherine A.; Garcia-Reyero, Natàlia; Martyniuk, Chris; Knoebl, Iris; Pope, Marie; Wright-Osment, Maureen K.; Denslow, Nancy D.; Tillitt, Donald E.

    2011-01-01

    Methylmercury (MeHg) is a potent neurotoxicant and endocrine disruptor that accumulates in aquatic systems. Previous studies have shown suppression of hormone levels in both male and female fish, suggesting effects on gonadotropin regulation in the brain. The gene expression profile in adult female zebrafish whole brain induced by acute (96 h) MeHg exposure was investigated. Fish were exposed by injection to 0 or 0.5(mu or u)g MeHg/g. Gene expression changes in the brain were examined using a 22,000-feature zebrafish microarray. At a significance level of pexposure. Individual genes exhibiting altered expression in response to MeHg exposure implicate effects on glutathione metabolism in the mechanism of MeHg neurotoxicity. Gene ontology (GO) terms significantly enriched among altered genes included protein folding, cell redox homeostasis, and steroid biosynthetic process. The most affected biological functions were related to nervous system development and function, as well as lipid metabolism and molecular transport. These results support the involvement of oxidative stress and effects on protein structure in the mechanism of action of MeHg in the female brain. Future studies will compare the gene expression profile induced in response to MeHg with that induced by other toxicants and will investigate responsive genes as potential biomarkers of MeHg exposure.

  20. Methylmercury Exposure and Health Effects from Rice and Fish Consumption: A Review

    PubMed Central

    Li, Ping; Feng, Xinbin; Qiu, Guangle

    2010-01-01

    Methylmercury (MeHg) is highly toxic, and its principal target tissue in humans is the nervous system, which has made MeHg intoxication a public health concern for many decades. The general population is primarily exposed to MeHg through consumption of contaminated fish and marine mammals, but recent studies have reported high levels of MeHg in rice and confirmed that in China the main human exposure to MeHg is related to frequent rice consumption in mercury (Hg) polluted areas. This article reviews the progress in the research on MeHg accumulation in rice, human exposure and health effects, and nutrient and co-contaminant interactions. Compared with fish, rice is of poor nutritional quality and lacks specific micronutrients identified as having health benefits (e.g., n-3 long chain polyunsaturated fatty acid, selenium, essential amino acids). The effects of these nutrients on the toxicity of MeHg should be better addressed in future epidemiologic and clinical studies. More emphasis should be given to assessing the health effects of low level MeHg exposure in the long term, with appropriate recommendations, as needed, to reduce MeHg exposure in the rice-eating population. PMID:20644695

  1. Developmental neurotoxicity: methylmercury and prenatal exposure protection in the context of the Minamata Convention.

    PubMed

    Boischio, Ana

    2015-09-01

    Mercury is a global pollutant of public environmental health concern due to its long-range atmospheric distribution, environmental distribution, and neurotoxic effects. Following biological methylation, methylmercury (MeHg) can be un-evenly bioaccumulated within aquatic food chains. Fish consumption can be a significant route of human exposure to MeHg. MeHg exposure in the prenatal stage, at relatively low levels, has recently been established as harmful during neurological development, potentially leading to intellectual disability. The Minamata Convention on Mercury is a global agreement, currently under ratification, to protect human health and the environment from anthropogenic emissions and releases of mercury and mercury compounds. The resolution regarding the role of the World Health Organization and ministries of health in the implementation of the Convention includes protection of human health from critical exposures to MeHg. Riverside populations living in areas with artisanal small-scale gold mining, and relying heavily on fish consumption, have been identified as the most vulnerable population in terms of MeHg exposure and developmental neurotoxicity. This article focuses on the proper design and dissemination of fish advisories within the context of implementation of the Convention. PMID:26758003

  2. Effects of Gestational Exposure to Methylmercury and Dietary Selenium on Reinforcement Efficacy in Adulthood

    PubMed Central

    Reed, Miranda N.; Banna, Kelly M.; Donlin, Wendy D.; Newland, M. Christopher

    2008-01-01

    It has recently been demonstrated that developmental exposure to methylmercury (MeHg) is associated with perseveration on operant tasks. An understanding of the behavioral mechanisms underlying this phenomenon may improve human testing of MeHg exposures and could provide insight into clinical syndromes that include perseveration as a component. One possible mechanism is that MeHg-induced enhancement of reinforcer efficacy produces a “reinforcement trap” that inhibits change in novel situations. Rats were exposed gestationally to 0, 0.5 or 5 ppm mercury (Hg) as MeHg via maternal drinking water. They also received a diet during gestation and throughout life that was marginal (0.06 ppm) or rich (0.6 ppm) in selenium (Se), a nutrient believed to protect against MeHg's toxicity. Reinforcer efficacy was evaluated using a progressive ratio schedule of reinforcement during adulthood. Maximum ratio obtained (MRO) was determined using 20 or 60 mg sucrose pellets and with ratio requirements that increased at 5% or 20% per reinforcer. MRO was related to the rate at which the ratio increased, reinforcer magnitude, sex, and exposure regimen; MRO was increased for the 0.6 ppm Se, 5 ppm Hg group. This extends an earlier observation that developmental MeHg exposure enhances reinforcer efficacy, an effect that could be related to reports of perseveration. PMID:18096364

  3. GENE EXPRESSION CHANGES IN FEMALE ZEBRAFISH (DANIO RERIO) BRAIN IN RESPONSE TO ACUTE EXPOSURE TO METHYLMERCURY

    PubMed Central

    Richter, Catherine A.; Garcia-Reyero, Natàlia; Martyniuk, Chris; Knoebl, Iris; Pope, Marie; Wright-Osment, Maureen K.; Denslow, Nancy D.; Tillitt, Donald E.

    2010-01-01

    Methylmercury (MeHg) is a potent neurotoxicant and endocrine disruptor that accumulates in aquatic systems. Previous studies have shown suppression of hormone levels in both male and female fish, suggesting effects on gonadotropin regulation in the brain. The gene expression profile in adult female zebrafish whole brain induced by acute (96 hr) MeHg exposure was investigated. Fish were exposed by injection to 0 or 0.5 μg MeHg/g. Gene expression changes in the brain were examined using a 22,000 feature zebrafish microarray. At a significance level of p<0.01, 79 genes were up-regulated and 76 genes were down-regulated in response to MeHg exposure. Individual genes exhibiting altered expression in response to MeHg exposure implicate effects on glutathione metabolism in the mechanism of MeHg neurotoxicity. Gene ontology (GO) terms significantly enriched among altered genes included protein folding, cell redox homeostasis, and steroid biosynthetic process. The most affected biological functions were related to the nervous system development and function, as well as lipid metabolism and molecular transport. These results support the involvement of oxidative stress and effects on protein structure in the mechanism of action of MeHg in the female brain. Future studies will compare the gene expression profile induced in response to MeHg with that induced by other toxicants and investigate responsive genes as potential biomarkers of MeHg exposure. PMID:21082716

  4. Neurodevelopmental Effects of Maternal Nutritional Status and Exposure to Methylmercury from Eating Fish during Pregnancy

    PubMed Central

    Davidson, Philip W.; Strain, J.J.; Myers, Gary J.; Thurston, Sally W.; Bonham, Maxine P.; Shamlaye, Conrad F.; Stokes-Riner, Abbie; Wallace, Julie M.W.; Robson, Paula J.; Duffy, Emeir M.; Georger, Lesley A.; Sloane-Reeves, Jean; Cernichiari, Elsa; Canfield, Richard L.; Cox, Christopher; Huang, Li Shan; Janciuras, Joanne; Clarkson, Thomas W.

    2008-01-01

    Fish contain nutrients that promote optimal brain growth and development but also contain methylmercury (MeHg) that can have toxic effects. The present study tested the hypothesis that the intake of selected nutrients in fish or measures of maternal nutritional status may represent important confounders when estimating the effects of prenatal methylmercury exposure on child development. The study took place in the Republic of Seychelles, an Indian Ocean archipelago where fish consumption is high. A longitudinal cohort study design was used. A total of 300 mothers were enrolled early in pregnancy. Nutrients considered to be important for brain development were measured during pregnancy along with prenatal MeHg exposure. The children were evaluated periodically to age 30 months. There were 229 children with complete outcome and covariate data for analysis. The primary endpoint was the Bayley Scales of Infant Development-II (BSID-II), administered at 9 and 30 months of age. Combinations of four secondary measures of infant cognition and memory were also given at 5, 9 and 25 months. Cohort mothers consumed an average of 537 gm of fish (9 meals containing fish) per week. The average prenatal MeHg exposure was 5.9 ppm in maternal hair. The primary analysis examined the associations between MeHg, maternal nutritional measures and children’s scores on the BSID-II and showed an adverse association between MeHg and the mean Psychomotor Developmental Index (PDI) score at 30 months. Secondary analyses of the association between the PDI and only MeHg alone or nutritional factors alone showed only a borderline significant association between MeHg and the PDI at 30 months and no associations with nutritional factors. One experimental measure at 5 months of age was positively associated with iodine status, but not prenatal MeHg exposure. These findings suggest a possible confounding role of maternal nutrition in studies examining associations between prenatal MeHg exposures and

  5. Methylmercury and nutrition: adult effects of fetal exposure in experimental models.

    PubMed

    Newland, M Christopher; Paletz, Elliott M; Reed, Miranda N

    2008-09-01

    Human exposure to the life-span developmental neurotoxicant, methylmercury (MeHg), is primarily via the consumption of fish or marine mammals. Fish are also excellent sources of important nutrients, including selenium and n-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Laboratory models of developmental MeHg exposure can be employed to assess the roles of nutrients and MeHg and to identify potential mechanisms of action if the appropriate exposure measures are used. When maternal exposure is protracted, relationships between daily intake and brain mercury are consistent and orderly across species, even when large differences in blood:brain ratios exist. It is well established that low-level developmental MeHg produces sensory deficits. Recent studies also show that perseveration in reversal-learning tasks occurs after gestational exposures that produce low micromolar concentrations in the brain. A no-effect level has not been identified for this effect. These exposures do not affect the acquisition or performance of discrimination learning, set shifting (extradimensional shift), or memory. Reversal-learning deficits may be related to enhanced impact of reinforcers as measured using progressive ratio reinforcement schedules, an effect that could result in perseveration. Also reported is enhanced sensitivity to dopamine reuptake inhibitors and diminished sensitivity to pentobarbital, a GABA(A) agonist. Diets rich in PUFAs or selenium do not protect against MeHg's effects on reversal learning but, by themselves, may diminish variability in performance, enhance attention or psychomotor function and may confer some protection against age-related deficits in these areas. It is hypothesized that altered reward processing, dopamine and GABAergic neurotransmitter systems, and cortical regions associated with choice and perseveration are especially sensitive to developmental MeHg at low exposure levels. Human testing for MeHg's neurotoxicity

  6. METHYLMERCURY AND NUTRITION: ADULT EFFECTS OF FETAL EXPOSURE IN EXPERIMENTAL MODELS

    PubMed Central

    Paletz, Elliott M.; Reed, Miranda N.

    2008-01-01

    Human exposure to the life-span developmental neurotoxicant, methylmercury (MeHg), is primarily via the consumption of fish or marine mammals. Fish are also excellent sources of important nutrients, including selenium and n-3 polyunsaturated fatty acids (PUFAs), such as docosahexaenoic acid (DHA). Laboratory models of developmental MeHg exposure can be employed to assess the roles of nutrients and MeHg and to identify potential mechanisms of action if the appropriate exposure measures are used. In describing chronic exposures, relationships between daily intake and brain mercury are consistent and orderly across species, even when large differences in blood:brain ratios exist. It is well-established that low level developmental MeHg produces sensory deficits. Recent studies also show that perseveration in reversal-learning tasks occurs after gestational exposures that produce low micromolar concentrations in the brain. A no-effect level has not been identified for this effect. These exposures do not affect the acquisition or performance of discrimination learning, set shifting (extra-dimensional shift), or memory. Reversal learning deficits may be related to enhanced impact of reinforcers as measured using progressive ratio reinforcement schedules, an effect that could result in perseveration. Also reported is enhanced sensitivity to dopamine reuptake inhibitors and diminished sensitivity to pentobarbital, a GABAA agonist. Diets rich in PUFAs or selenium do not protect against MeHg's effects on reversal learning but, by themselves, may diminish variability in performance, enhance attention or psychomotor function and may confer some protection against age-related deficits in these areas. It is hypothesized that altered reward processing, dopamine and GABAergic neurotransmitter systems, and cortical regions associated with choice and perseveration are especially sensitive to developmental MeHg at low exposure levels. Human testing for MeHg's neurotoxicity should

  7. A Hypothesis About How Early Developmental Methylmercury Exposure Disrupts Behavior in Adulthood

    PubMed Central

    Newland, M. Christopher; Reed, Miranda N.; Rasmussen, Erin

    2015-01-01

    Events that disrupt the early development of the nervous system have lifelong, irreversible behavioral consequences. The environmental contaminant, methylmercury (MeHg), impairs neural development with effects that are manifested well into adulthood and even into aging. Noting the sensitivity of the developing brain to MeHg, the current review advances an argument that one outcome of early MeHg exposure is a distortion in the processing of reinforcing consequences that results in impaired choice, poor inhibition of prepotent responding, and perseveration on discrimination reversals (in the absence of alteration of extradimensional shifts). Neurochemical correlates include increased sensitivity to dopamine agonists and decreased sensitivity to gamma-aminobutyric acid (GABA) agonists. This leads to a hypothesis that the prefrontal cortex or dopamine neurotransmission is especially sensitive to even subtle gestational MeHg exposure and suggests that public health assessments of MeHg based on intellectual performance may underestimate the impact of MeHg in public health. Finally, those interested in modeling neural development may benefit from MeHg as an experimental model. PMID:25795099

  8. Assessing exposure risks for freshwater tilapia species posed by mercury and methylmercury.

    PubMed

    Cheng, Yi-Hsien; Lin, Yi-Jun; You, Shu-Han; Yang, Ying-Fei; How, Chun Ming; Tseng, Yi-Ting; Chen, Wei-Yu; Liao, Chung-Min

    2016-08-01

    Waterborne and dietborne exposures of freshwater fish to mercury (Hg) in the forms of inorganic (Hg(II)) and organic (methylmercury or MeHg) affect their growth, development, and reproduction. However, an integrated mechanistic risk model framework to predict the impact of Hg(II)/MeHg on freshwater fish is lacking. Here, we integrated biokinetic, physiological and biogeographic data to calibrate and then establish key risk indices-hazardous quotient and exceedance risk-for freshwater tilapia species across geographic ranges of several major rivers in Taiwan. We found that Hg(II) burden was highest in kidney followed by gill, intestine, liver, blood, and muscle. Our results showed that Hg was less likely to pose mortality risk (mortality rate less than 5 %) for freshwater tilapia species. However, Hg is likely to pose the potential hazard to aquatic environments constrained by safety levels for aquatic organisms. Sensitivity analysis showed that amount of Hg accumulated in tilapia was most influenced by sediment uptake rate. Our approach opens up new possibilities for predicting future fish population health with the impacts of continued Hg exposure to provide information on which fish are deemed safe for human consumption. PMID:27207496

  9. Evidence on the Human Health Effects of Low-Level Methylmercury Exposure

    PubMed Central

    Choi, Anna L.; Oken, Emily; Horvat, Milena; Schoeny, Rita; Kamai, Elizabeth; Cowell, Whitney; Grandjean, Philippe; Korrick, Susan

    2012-01-01

    Background: Methylmercury (MeHg) is a known neuro-toxicant. Emerging evidence indicates it may have adverse effects on the neuro-logic and other body systems at common low levels of exposure. Impacts of MeHg exposure could vary by individual susceptibility or be confounded by bene-ficial nutrients in fish containing MeHg. Despite its global relevance, synthesis of the available literature on low-level MeHg exposure has been limited. Objectives: We undertook a synthesis of the current knowledge on the human health effects of low-level MeHg exposure to provide a basis for future research efforts, risk assessment, and exposure remediation policies worldwide. Data sources and extraction: We reviewed the published literature for original human epidemio-logic research articles that reported a direct biomarker of mercury exposure. To focus on high-quality studies and those specifically on low mercury exposure, we excluded case series, as well as studies of populations with unusually high fish consumption (e.g., the Seychelles), marine mammal consumption (e.g., the Faroe Islands, circumpolar, and other indigenous populations), or consumption of highly contaminated fish (e.g., gold-mining regions in the Amazon). Data synthesis: Recent evidence raises the possibility of effects of low-level MeHg exposure on fetal growth among susceptible subgroups and on infant growth in the first 2 years of life. Low-level effects of MeHg on neuro-logic outcomes may differ by age, sex, and timing of exposure. No clear pattern has been observed for cardio-vascular disease (CVD) risk across populations or for specific CVD end points. For the few studies evaluating immunologic effects associated with MeHg, results have been inconsistent. Conclusions: Studies targeted at identifying potential mechanisms of low-level MeHg effects and characterizing individual susceptibility, sexual dimorphism, and non-linearity in dose response would help guide future prevention, policy, and regulatory efforts

  10. The role of gut microbiota in fetal methylmercury exposure: Insights from a pilot study

    DOE PAGESBeta

    Rothenberg, Sarah E.; Keiser, Sharon; Ajami, Nadim J.; Wong, Matthew C.; Gesell, Jonathan; Petrosino, Joseph F.; Johs, Alexander

    2016-02-01

    The mechanisms by which gut microbiota contribute to methylmercury metabolism remain unclear. Among a cohort of pregnant mothers, the main objectives of our pilot study were to determine 1) associations between gut microbiota and mercury concentrations in biomarkers (stool, hair and cord blood) and 2) the contributions of gut microbial mercury methylation/demethylation to stool methylmercury. Moreover, for pregnant women (36-39 weeks gestation, n=17) donated hair and stool specimens, and cord blood was collected for a subset (n=7). The diversity of gut microbiota was determined using 16S rRNA gene profiling (n=17). For 6 stool samples with highest/lowest methylmercury concentrations, metagenomic wholemore » genome shotgun sequencing was employed to search for one mercury methylation gene (hgcA), and two mer operon genes involved in methylmercury detoxification (merA and merB). There were seventeen bacterial genera that were significantly correlated (increasing or decreasing) with stool methylmercury, stool inorganic mercury, or hair total mercury; however, aside from one genus, there was no overlap between biomarkers. No definitive matches for hgcA or merB, while merA were detected at low concentrations in all six samples. Proportional differences in stool methylmercury were not likely attributed to gut microbiota through methylation/demethylation. Gut microbiota potentially altered methylmercury metabolism using indirect pathways.« less

  11. Assessing pre/post-weaning neurobehavioral development for perinatal exposure to low doses of methylmercury.

    PubMed

    Cheng, Jinping; Fujimura, Masatake; Bo, Dandan

    2015-12-01

    Fetuses and neonates are known to be high-risk groups for Methylmercury (MeHg) exposure. MeHg can be transferred to the fetus through the placenta and to newborn offspring through breast milk. The aim of the present study was to investigate the neurotoxic effects of low doses of MeHg (1 and 5μg/mL in drinking water) administration, from gestational day 1 to postnatal day (PND) 21, on the neurobehavioral development of rats. The results showed that the no-observed-effect level of MeHg is somewhere in the range of 1-4μg/mL. Neurobehavioral development analysis revealed a delayed appearance of cliff drop and negative geotaxis reflexes in the 5μg/mL MeHg exposure group. Developmental exposure to MeHg affected locomotor activity functions for the females, but not for the males, implying that the female pups were more vulnerable than the male pups. All pups exposed to 5μg/mL of MeHg showed a significant deficit in motor coordination in the rotarod test compared with controls, and the highest accumulated concentrations of Hg were found in the cerebellum, followed by the hippocampus and cerebral cortex, indicating that the cerebellum is a possible target for MeHg toxicity. We demonstrated adverse effects of developmental exposure to MeHg associated with tissue concentrations very close to the current human body burden of this persistent and bioaccumulative compound. PMID:26702966

  12. Brain and tissue levels of mercury after chronic methylmercury exposure in the monkey

    SciTech Connect

    Rice, D.C.

    1989-01-01

    Estimated half-lives of mercury following methylmercury exposure in humans are 52-93 d for whole body and 49-164 d for blood. In its most recent 1980 review, the World Health Organization concluded that there was no evidence to suggest that brain half-life differed from whole-body half-life. In the present study, female monkeys (Macaca fascicularis) were dosed for at least 1.7 yr with 10, 25, or 50 micrograms/kg.d of mercury as methylmercuric chloride. Dosing was discontinued, and blood half-life was determined to be about 14 d. Approximately 230 d after cessation of dosing, monkeys were sacrificed and organ and regional brain total mercury levels determined. One monkey that died while still being dosed had brain mercury levels three times higher than levels in blood. Theoretical calculations were performed assuming steady-state brain:blood ratios of 3, 5, or 10. Brain mercury levels were at least three orders of magnitude higher than those predicted by assuming the half-life in brain to be the same as that in blood. Estimated half-lives in brain were between 56 (brain:blood ratio of 3) and 38 (brain:blood ratio of 10) d. In addition, there was a dose-dependent difference in half-lives for some brain regions. These data clearly indicate that brain half-life is considerably longer than blood half-life in the monkey under conditions of chronic dosing.

  13. Methylmercury exposure and neurological outcomes in Taiji residents accustomed to consuming whale meat.

    PubMed

    Nakamura, Masaaki; Hachiya, Noriyuki; Murata, Ken-ya; Nakanishi, Ichiro; Kondo, Tomoyoshi; Yasutake, Akira; Miyamoto, Ken-ichiro; Ser, Ping Han; Omi, Sanae; Furusawa, Hana; Watanabe, Chiho; Usuki, Fusako; Sakamoto, Mineshi

    2014-07-01

    Methylmercury (MeHg) is a major environmental neurotoxicant that causes damage to the central nervous system. In Japan, industrial emission of MeHg has resulted in MeHg intoxication in Minamata and Niigata, the so-called Minamata disease. Humans are exposed to MeHg derived from natural sources, primarily fish and fish predators. Therefore, MeHg continues to be an environmental risk to human health, particularly in susceptible populations that frequently consume substantial amounts of fish or fish predators such as whale. This study aimed to investigate the health effects of MeHg exposure in adults. The subjects were 194 residents (117 males, 77 females; age 20-85 years) who resided in the coastal town of Taiji, the birthplace of traditional whaling in Japan. We analyzed hair for mercury content and performed detailed neurological examinations and dietary surveys. Audiometry, magnetic resonance imaging, and electromyography were performed to diagnose neurological defects. Whole blood mercury and selenium (Se) levels were measured in 23 subjects. The geometric mean of the hair mercury levels was 14.9 μg/g. Twelve subjects revealed hair mercury levels >50 μg/g (NOAEL) set by WHO. Hair mercury levels significantly correlated with daily whale meat intake. These results suggested that residents in Taiji were highly exposed to MeHg by ingesting MeHg-contaminated whale meat. Multivariate regression analysis demonstrated no significant correlations between hair mercury levels and neurological outcomes, whereas some of the findings significantly correlated with age. A significantly positive correlation between whole blood mercury and Se levels was observed and the whole blood mercury/Se molar ratios of all subjects were <1. These findings suggested that sufficient Se intake might be one of causes of the absence of adverse effects of MeHg exposure in this study. PMID:24685489

  14. Biomarkers of Methylmercury Exposure Immunotoxicity among Fish Consumers in Amazonian Brazil

    PubMed Central

    Fillion, Myriam; Barbosa, Fernando; Shirley, Devon L.; Chine, Chiameka; Lemire, Melanie; Mergler, Donna; Silbergeld, Ellen K.

    2011-01-01

    Background: Mercury (Hg) is a ubiquitous environmental contaminant with neurodevelopmental and immune system effects. An informative biomarker of Hg-induced immunotoxicity could aid studies on the potential contribution to immune-related health effects. Objectives: Our objectives were to test the hypothesis that methylmercury (MeHg) exposures affect levels of serum biomarkers and to examine interactions between Hg and selenium (Se) in terms of these responses. Methods: This cross-sectional epidemiological study assessed adults living along the Tapajós River, a system long affected by MeHg. We measured antinuclear (ANA) and antinucleolar (ANoA) autoantibody levels and eight cytokines in serum samples (n = 232). Total Hg (including MeHg) and Se were measured in blood, plasma, hair, and urine. Results: The median (range) total Hg concentrations were 14.1 μg/g (1.1–62.4), 53.5 μg/L (4.3–288.9), 8.8 μg/L (0.2–40), and 3.0 μg/L (0.2–16.1) for hair, blood, plasma, and urine, respectively. Elevated titers of ANA (but not ANoA) were positively associated with MeHg exposure (log-transformed, for blood and plasma), unadjusted [odds ratio (OR) = 2.6; 95% confidence interval (CI): 1.1, 6.2] and adjusted for sex and age (OR = 2.9; 95% CI: 1.1, 7.5). Proinflammatory [interleukin (IL)-6 and interferon (IFN)-©], anti-inflammatory (IL-4), and IL-17 cytokine levels were increased with MeHg exposure; however, in the subset of the population with elevated ANA, proinflammatory IL-1®, IL-6, IFN-©, and tumor necrosis factor (TNF)-〈 and anti-inflammatory (IL-4) cytokine levels were decreased with MeHg exposure. Although Se status was associated with MeHg level (correlation coefficient = 0.86; 95% CI: 0.29, 1.43), Se status was not associated with any changes in ANA and did not modify associations between Hg and ANA titers. Conclusions: MeHg exposure was associated with an increased ANA and changes in serum cytokine profile. Moreover, alterations in serum cytokine profiles

  15. In Inland China, Rice, Rather than Fish, Is the Major Pathway for Methylmercury Exposure

    PubMed Central

    Zhang, Hua; Feng, Xinbin; Larssen, Thorjørn; Qiu, Guangle; Vogt, Rolf D.

    2010-01-01

    Background Fish consumption is considered the primary pathway of methylmercury (MeHg) exposure for most people in the world. However, in the inland regions of China, most of the residents eat little fish, but they live in areas where a significant amount of mercury (Hg) is present in the environment. Objectives We assessed concentrations of total Hg and MeHg in samples of water, air, agricultural products, and other exposure media to determine the main exposure pathway of Hg in populations in inland China. Methods We selected Guizhou Province for our study because it is highly contaminated with Hg and therefore is representative of other Hg-contaminated areas in China. We selected four study locations in Guizhou Province: three that represent typical environments with severe Hg pollution [due to Hg mining and smelting (Wanshan), traditional zinc smelting (recently closed; Weining), and heavy coal-based industry (Qingzhen)], and a village in a remote nature reserve (Leigong). Results The probable daily intake (PDI) of MeHg for an adult population based on 60 kg body weight (bw) was considerably higher in Wanshan than in the other three locations. With an average PDI of 0.096 μg/kg bw/day (range, 0.015–0.45 μg/kg bw/day), approximately 34% of the inhabitants in Wanshan exceeded the reference dose of 0.1 μg/kg bw/day established by the U.S. Environmental Protection Agency. The PDI of MeHg for residents in the three other locations were all well below 0.1 μg/kg bw/day (averages from 0.017 to 0.023 μg/kg bw/day, with a maximum of 0.095 μg/kg bw/day). In all four areas, rice consumption accounted for 94–96% of the PDI of MeHg. Conclusion We found that rice consumption is by far the most important MeHg exposure route; however, most of the residents (except those in Hg-mining areas) have low PDIs of MeHg. PMID:20378486

  16. Global methylmercury exposure from seafood consumption and risk of developmental neurotoxicity: a systematic review

    PubMed Central

    Burke, Thomas A; Navas-Acien, Ana; Breysse, Patrick N; McGready, John; Fox, Mary A

    2014-01-01

    Abstract Objective To examine biomarkers of methylmercury (MeHg) intake in women and infants from seafood-consuming populations globally and characterize the comparative risk of fetal developmental neurotoxicity. Methods A search was conducted of the published literature reporting total mercury (Hg) in hair and blood in women and infants. These biomarkers are validated proxy measures of MeHg, a neurotoxin found primarily in seafood. Average and high-end biomarkers were extracted, stratified by seafood consumption context, and pooled by category. Medians for average and high-end pooled distributions were compared with the reference level established by a joint expert committee of the Food and Agriculture Organization (FAO) and the World Health Organization (WHO). Findings Selection criteria were met by 164 studies of women and infants from 43 countries. Pooled average biomarkers suggest an intake of MeHg several times over the FAO/WHO reference in fish-consuming riparians living near small-scale gold mining and well over the reference in consumers of marine mammals in Arctic regions. In coastal regions of south-eastern Asia, the western Pacific and the Mediterranean, average biomarkers approach the reference. Although the two former groups have a higher risk of neurotoxicity than the latter, coastal regions are home to the largest number at risk. High-end biomarkers across all categories indicate MeHg intake is in excess of the reference value. Conclusion There is a need for policies to reduce Hg exposure among women and infants and for surveillance in high-risk populations, the majority of which live in low-and middle-income countries. PMID:24700993

  17. Porphyrins as biomarkers of methylmercury and PCB exposure in experimental quail

    SciTech Connect

    Leonzio, C.; Fossi, M.C.; Casini, S.

    1996-02-01

    Chemicals such as heavy metals and polyhalogenated hydrocarbons have a high capacity to interfere with the enzymatic processes responsible for haem biosynthesis. These compounds can produce accumulation in tissues and organs and increased elimination of porphyrins in excreta. The development of fast and easy analytical methods and the wide variety of biological media in which porphynins can be detected have suggested their use as biomarkers of environmental pollution. The analysis of porphynins in the excreta is of special interest because it enables non-destructive monitoring of wild animals in the assessment of threatened or endangered species. Methylmercury and PCBs are ubiquitous global pollutants and there is evidence they accumulate in ternfuinal consumers, particularly those belonging to marine trophic chain. There have been some reports on methylmercury-induced and PCB-induced porphyria but little data on their combined effect. In order to investigate the quality of porphyrins as biomarkers we performed an experiment in which Japanese quail were fed a diet containing methylmercury and polychlorobyphenyls (PCBs as Arochlor 1260) individually or combined in different ratios. The present study aims to provide preliminary data on liver and fecal levels of porphynins in response to methylmercury and PCB administration, and on whether the indicator is sensitive to synergism or antagonism between the two compounds, administered simultaneously.

  18. Transcriptomic and Physiological Responses of the Green Microalga Chlamydomonas reinhardtii during Short-Term Exposure to Subnanomolar Methylmercury Concentrations.

    PubMed

    Beauvais-Flück, Rebecca; Slaveykova, Vera I; Cosio, Claudia

    2016-07-01

    The effects of short-term exposure to subnanomolar methyl-mercury (MeHg) concentrations, representative of contaminated environments, on the microalga Chlamydomonas reinhardtii were assessed using both physiological end points and gene expression analysis. MeHg bioaccumulated and induced significant increase of the photosynthesis efficiency, while the algal growth, oxidative stress, and chlorophyll fluorescence were unaffected. At the molecular level, MeHg significantly dysregulated the expression of genes involved in motility, energy metabolism, lipid metabolism, metal transport, and antioxidant enzymes. Data suggest that the cells were able to cope with subnanomolar MeHg exposure, but this tolerance resulted in a significant cost to the cell energy and reserve metabolism as well as ample changes in the nutrition and motility of C. reinhardtii. The present results allowed gaining new insights on the effects and uptake mechanisms of MeHg at subnanomolar concentrations in aquatic primary producers. PMID:27254783

  19. EFFECTS OF SUBSCUTE EXPOSURE TO NANOMOLAR CONCENTRATIONS OF METHYLMERCURY ON VOLTAGE-GATES SODIUM AND CALCIUM CURRENTS IN PC12 CELLS.

    EPA Science Inventory

    Methylmercury (CH3Hg+) alters the function of voltage-gated Na+ and Ca2+ channels in neuronal preparations following acute, in vitro, exposure. Because the developing nervous system is particularly sensitive to CH3Hg+ neurotoxicity, effects on voltage-gated Na+ (INa) and Ca2+ (IC...

  20. Effects of embryonic exposure to methylmercury on larval prey-capture ability in the mummichog, Fundulus heteroclitus

    SciTech Connect

    Weis, J.S. . Dept. of Biological Sciences); Weis, P. . Dept. of Anatomy, Cell Biology and Injury Science)

    1995-01-01

    Embryos of the mummichog (Fundulus heteroclitus) were exposed to 2, 5, or 10 [mu]g/L methylmercury (meHg) throughout development; these are concentrations below those which cause teratological effects in this species. After hatching, larvae were maintained in clean seawater and tested for pre-capture ability, using Artemia salina nauplii. Larvae that had been exposed to 10 [mu]g/L methylmercury initially exhibited slower prey-capture ability than did the other groups. This is an indication of a subtle functional impairment due to the toxicant (behavioral teratology). However, the effect was transitory, and by about 1 week after hatching the pre capture of these larvae equaled that of the controls and the other treated groups. Growth of these larvae was also comparable to that of controls. The exposure may have caused retardation of neurological development, which was subsequently compensated for, and therefore no long-lasting effects were produced. In the field, however, embryos exposed to toxicants would probably continue to be exposed as larvae, and might not have the opportunity to recover from the deleterious effects, but rather might have them augmented.

  1. Perturbation of myelin basic protein (Mbp) splice variant expression in developing rat cerebellum following perinatal exposure to methylmercury.

    PubMed

    Padhi, Bhaja K; Pelletier, Guillaume

    2012-09-18

    Myelin sheaths surrounding axons are essential for saltatory conduction of nerve impulse in the central nervous system. A major protein constituent of myelin sheaths is produced by the myelin basic protein (Mbp) gene, whose expression in oligodendrocytes is conserved across vertebrates. In rat, five Mbp splice variants resulting from alternative splicing of exons 2, 5 and/or 6 are characterized. We developed a PCR-based strategy to quantify individual Mbp splice variants and characterized a sixth Mbp splice variant lacking only exon 5. This newly identified splice variant is predominantly expressed in developing rat brain and has orthologs in mouse and human. Many neurotoxic chemicals can perturb myelination and Mbp gene expression. Regulation of Mbp gene expression at the post-transcriptional level was assessed following perinatal exposure to neurotoxic methylmercury (2 mg/kg b.w./day). Similar reductions in total and individual Mbp splice variant mRNA levels suggest that methylmercury-induced perturbation in Mbp gene expression occurred as a consequence of decreased oligodendrocyte cell population in absence of a significant impact on its post-transcriptional regulation. PMID:22835759

  2. Neurobehavioral effect of chronic and bolus doses of methylmercury following prenatal exposure in C57BL/6 weanling mice.

    PubMed

    Liang, Jacky; Inskip, Mike; Newhook, Deborah; Messier, Claude

    2009-01-01

    Several studies with animals have shown that even low and medium prenatal and postnatal exposure to methylmercury (MeHg) can result in locomotor, motor coordination and learning deficits. However, some behavioural effects of MeHg remain controversial and the methods to model human MeHg exposure in animal still remain to be optimized. We investigated the neurobehavioral effects of two different patterns of MeHg exposure. MeHg was given mixed in palatable food that mice readily ate. For the first pattern (chronic group), C57BL/6 mice dams were given 1.4 microg/g body weight (BW)/day (n=20) throughout gestation mixed in palatable food. For the second pattern (bolus) dams were given 6.0 microg/g BW/day mixed in palatable food on gestation day 12 and 16 together with a lower chronic dose of 0.85 microg/g BW/day mixed in palatable food on all remaining gestation days (n=20). Day 12 and 16 were chosen because neuron proliferation and the start of migration for many brain regions occur during that period. Behavioural testing on weanling animals started at 8 weeks. Both the chronic and bolus groups showed an impairment of working memory and visual spatial ability in the radial arm maze task. Other tests did not provide clear evidence that methylmercury exposure had significant adverse effects on locomotor activity, motor coordination or emotional reactivity. However, the chronic groups had a tendency for lower performance in most tests including activity in Skinner box and open field trials, as well as a higher number of anxiety-like behaviors. Chronic exposure to lower levels of MeHg combined to acute exposure with high levels of a few days during gestation appears to be less damaging than chronic exposure to slightly higher levels without acute MeHg exposure even though, equal amounts were administered during gestation. Possibly, as indicated by preliminary data, the relatively larger impact of chronic administration of a higher daily dose could be the consequence of a

  3. Balancing the benefits of n-3 polyunsaturated fatty acids and the risks of methylmercury exposure from fish consumption

    PubMed Central

    Mahaffey, Kathryn R; Sunderland, Elsie M; Chan, Hing Man; Choi, Anna L; Grandjean, Philippe; Mariën, Koenraad; Oken, Emily; Sakamoto, Mineshi; Schoeny, Rita; Weihe, Pál; Yan, Chong-Huai; Yasutake, Akira

    2011-01-01

    Fish and shellfish are widely available foods that provide important nutrients, particularly n-3 polyunsaturated fatty acids (n-3 PUFAs), to many populations globally. These nutrients, especially docosahexaenoic acid, confer benefits to brain and visual system development in infants and reduce risks of certain forms of heart disease in adults. However, fish and shellfish can also be a major source of methylmercury (MeHg), a known neurotoxicant that is particularly harmful to fetal brain development. This review documents the latest knowledge on the risks and benefits of seafood consumption for perinatal development of infants. It is possible to choose fish species that are both high in n-3 PUFAs and low in MeHg. A framework for providing dietary advice for women of childbearing age on how to maximize the dietary intake of n-3 PUFAs while minimizing MeHg exposures is suggested. PMID:21884130

  4. Early Developmental Low-Dose Methylmercury Exposure Alters Learning and Memory in Periadolescent but Not Young Adult Rats

    PubMed Central

    Albores-Garcia, Damaris; Hernandez, Alberto J.; Loera, Miriam J.

    2016-01-01

    Few studies have assessed the effects of developmental methylmercury (MeHg) exposure on learning and memory at different ages. The possibility of the amelioration or worsening of the effects has not been sufficiently investigated. This study aimed to assess whether low-dose MeHg exposure in utero and during suckling induces differential disturbances in learning and memory of periadolescent and young adult rats. Four experimental groups of pregnant Sprague-Dawley rats were orally exposed to MeHg or vehicle from gestational day 5 to weaning: (1) control (vehicle), (2) 250 μg/kg/day MeHg, (3) 500 μg/kg/day MeHg, and (4) vehicle, and treated on the test day with MK-801 (0.15 mg/kg i.p.), an antagonist of the N-methyl D-aspartate receptor. The effects were evaluated in male offspring through the open field test, object recognition test, Morris water maze, and conditioned taste aversion. For each test and stage assessed, different groups of animals were used. MeHg exposure, in a dose-dependent manner, disrupted exploratory behaviour, recognition memory, spatial learning, and acquisition of aversive memories in periadolescent rats, but alterations were not observed in littermates tested in young adulthood. These results suggest that developmental low-dose exposure to MeHg induces age-dependent detrimental effects. The relevance of decreasing exposure to MeHg in humans remains to be determined. PMID:26885512

  5. Modeled methylmercury exposure and risk from rice consumption for vulnerable populations in a traditional fish-eating area in China.

    PubMed

    Tong, Yin-Dong; Ou, Lang-Bo; Chen, Long; Wang, Huan-Huan; Chen, Cen; Wang, Xue-Jun; Zhang, Wei; Wang, Qi-Guang

    2015-05-01

    The circulation of rice from contaminated areas could escalate exposure risk from a local problem to a national issue and affect a wider population beyond the region of origin, as confirmed by the "Poison Rice Incident" in May 2013 in Guangzhou, China. In the present study, the authors established a food chain model based on the aquivalence method to identify major sources of methylmercury (MeHg), estimate the levels of MeHg, and quantify exposure to MeHg via rice and aquatic food consumption. Different types of organism samples from the Haihe River also were collected to verify the calculated values. The MeHg intake in pregnant women was 1529.1 ng/d from the aquatic food chain and as high as 2804.0 ng/d from rice, although the intake varied among scenarios. The maximum possible MeHg concentration in the blood of pregnant women was 5.21 µg/L, higher than the threshold value of MeHg recommended by the US Environmental Protection Agency (4.4 µg/L), which indicated that pregnant women could face risk from MeHg exposure. The authors also assessed the risk of MeHg exposure in pregnant women and their breastfed infants using a new index, HQEquivalent . In 4 scenarios, the HQEquivalent indices ranged from 0.42 to 1.18 for pregnant women and from 0.29 to 0.83 for breastfed infants. PMID:25639888

  6. Methylmercury poisoning

    MedlinePlus

    ... mercury , a metal that is liquid at room temperature. A nickname for mercury is quicksilver. Most compounds ... methylmercury are present in many foods from the ocean, including deep-sea tuna. Fortunately, the levels are ...

  7. Prenatal methylmercury exposure and language delay at three years of age in the Norwegian Mother and Child Cohort Study.

    PubMed

    Vejrup, Kristine; Schjølberg, Synnve; Knutsen, Helle Katrine; Kvalem, Helen Engelstad; Brantsæter, Anne Lise; Meltzer, Helle Margrete; Alexander, Jan; Magnus, Per; Haugen, Margaretha

    2016-01-01

    Prenatal methylmercury (MeHg) exposure and its possible neurodevelopmental effects in susceptible children are of concern. Studies of MeHg exposure and negative health outcomes have shown conflicting results and it has been suggested that co-exposure to other contaminants and/or nutrients in fish may confound the effect of MeHg. Our objective was to examine the association between prenatal exposure to MeHg and language and communication development at three years, adjusting for intake of fish, n-3 long chain polyunsaturated fatty acids (n-3 LCPUFAs) and co-exposure to dioxins and dioxin like polychlorinated biphenyls (dl-PCBs). We used data from the Norwegian Mother and Child Cohort Study (MoBa) collected between 2002 and 2008. The study sample consisted of 46,750 mother-child pairs. MeHg exposure was calculated from reported fish intake during pregnancy by a FFQ in mid-pregnancy. Children's language and communication skills were measured by maternal report on the Dale and Bishop grammar rating and the Ages and Stages communication scale (ASQ). We estimated odds ratios (OR) and 95% confidence intervals (CI) using logistic regressions. Median MeHg exposure was 1.3μg/day, corresponding to 0.14μg/kgbw/week. An exposure level above the 90th percentile (>2.6μg/day, >0.29μg/kgbw/week) was defined as the high MeHg exposure. Results indicated an association between high MeHg exposure and unintelligible speech with an adjusted OR 2.22 (1.31, 3.72). High MeHg exposure was also associated with weaker communication skills adjusted OR 1.33 (1.03, 1.70). Additional adjustment for fish intake strengthened the associations, while adjusting for PCBs and n-3 LCPUFA from diet or from supplements had minor impact. In conclusion, significant associations were found between prenatal MeHg exposure above the 90th percentile and delayed language and communication skills in a generally low exposed population. PMID:27058928

  8. Parental Whole Life Cycle Exposure to Dietary Methylmercury in Zebrafish (Danio rerio) Affects the Behavior of Offspring.

    PubMed

    Mora-Zamorano, Francisco X; Klingler, Rebekah; Murphy, Cheryl A; Basu, Niladri; Head, Jessica; Carvan, Michael J

    2016-05-01

    Methylmercury (MeHg) is an established neurotoxicant of concern to fish-eating organisms. While most studies have focused on the fish consumers, much less is known about the effects of MeHg on the fish themselves, especially following exposures to chronic and environmentally relevant scenarios. Here we evaluated the behavioral effects of developmental MeHg insult by exposing parental generations of zebrafish to an environmentally realistic MeHg dietary concentration (1 ppm) and two higher concentrations (3 and 10 ppm) throughout their whole life span. Upon reaching adulthood, their offspring were analyzed through a series of behavioral tests, including the visual-motor response (VMR) assay, analysis of spontaneous swimming and evaluation of foraging efficiency. The VMR assay identified decreased locomotor output in the 6 day postfertilization (dpf) offspring of fish exposed to 3 and 10 ppm MeHg. However, in a second test 7 dpf fish revealed an increase in locomotor activity in all MeHg exposures tested. Increases in locomotion continued to be observed until 16 dpf, which coincided with increased foraging efficiency. These results suggest an association between MeHg and hyperactivity, and imply that fish chronically exposed to MeHg in the wild may be vulnerable to predation. PMID:27023211

  9. Mercury Isotope Study of Sources and Exposure Pathways of Methylmercury in Estuarine Food Webs in the Northeastern U.S.

    PubMed Central

    2015-01-01

    We measured mercury (Hg) isotope ratios in sediments and various estuarine organisms (green crab, blue mussel, killifish, eider) to investigate methylmercury (MMHg) sources and exposure pathways in five Northeast coast (U.S.) estuaries. The mass independent Hg isotopic compositions (MIF; Δ199Hg) of the sediments were linearly correlated with the sediment 1/Hg concentrations (Δ199Hg: r2 = 0.77, p < 0.05), but the mass dependent isotope compositions (MDF; δ202Hg) were not (r2 = 0.26, p = 0.16), reflecting inputs of anthropogenic Hg sources with varying δ202Hg. The estuarine organisms all display positive Δ199Hg values (0.21 to 0.98 ‰) indicating that MMHg is photodegraded to varying degrees (5–12%) prior to entry into the food web. The δ202Hg and Δ199Hg values of most organisms can be explained by a mixture of MMHg and inorganic Hg from sediments. At one contaminated site mussels have anomalously high δ202Hg, indicating exposure to a second pool of MMHg, compared to sediment, crabs and fish. Eiders have similar Δ199Hg as killifish but much higher δ202Hg, suggesting that there is an internal fractionation of δ202Hg in birds. Our study shows that Hg isotopes can be used to identify multiple anthropogenic inorganic Hg and MMHg sources and determine the degree of photodegradation of MMHg in estuarine food webs. PMID:25116221

  10. Mercury isotope study of sources and exposure pathways of methylmercury in estuarine food webs in the Northeastern U.S.

    PubMed

    Kwon, Sae Yun; Blum, Joel D; Chen, Celia Y; Meattey, Dustin E; Mason, Robert P

    2014-09-01

    We measured mercury (Hg) isotope ratios in sediments and various estuarine organisms (green crab, blue mussel, killifish, eider) to investigate methylmercury (MMHg) sources and exposure pathways in five Northeast coast (U.S.) estuaries. The mass independent Hg isotopic compositions (MIF; Δ(199)Hg) of the sediments were linearly correlated with the sediment 1/Hg concentrations (Δ(199)Hg: r(2) = 0.77, p < 0.05), but the mass dependent isotope compositions (MDF; δ(202)Hg) were not (r(2) = 0.26, p = 0.16), reflecting inputs of anthropogenic Hg sources with varying δ(202)Hg. The estuarine organisms all display positive Δ(199)Hg values (0.21 to 0.98 ‰) indicating that MMHg is photodegraded to varying degrees (5-12%) prior to entry into the food web. The δ(202)Hg and Δ(199)Hg values of most organisms can be explained by a mixture of MMHg and inorganic Hg from sediments. At one contaminated site mussels have anomalously high δ(202)Hg, indicating exposure to a second pool of MMHg, compared to sediment, crabs and fish. Eiders have similar Δ(199)Hg as killifish but much higher δ(202)Hg, suggesting that there is an internal fractionation of δ(202)Hg in birds. Our study shows that Hg isotopes can be used to identify multiple anthropogenic inorganic Hg and MMHg sources and determine the degree of photodegradation of MMHg in estuarine food webs. PMID:25116221

  11. Assessing noxious effects of dietary exposure to methylmercury, PCBs and Se coexisting in environmentally contaminated rice in male mice.

    PubMed

    Cheng, Jinping; Yang, Yichen; Ma, Jing; Wang, Wenhua; Liu, Xiaojie; Sakamoto, Mineshi; Qu, Yiya; Shi, Wei

    2009-04-01

    Polychlorinated biphenyls and methylmercury are two of the most ubiquitous environmental contaminants in Guizhou province. Rice is eaten with almost every meal and provides more calories than any single food in Guizhou province. The estimated tolerable daily intake of total mercury, MeHg, Se and PCBs from Guizhou contaminated rice by Chinese people showed that MeHg and/or PCBs exceeded the corresponding limits. The aim of this study was to characterize the effects of exposure to environmental contaminated rice on neurobehavioral development and neurobiological disruptions in mice. Animals were treated from postnatal day (PND) 22 to 91. At PND 26-91 days of age, mice were tested for neurobehavioural development and neurochemical level changes. We showed that dietary exposure to environmentally contaminated rice gave rise to different changes in antioxidants. Reduced superoxide dismutase (SOD) activity and excess increased nitric oxide (NO) indicated aggravation of oxidative status after long-term dietary intake of Hg and PCBs. Neurobehavioral derangement in the central nervous system and significant delay in the Morris water maze test response on PND 91 are correlated with the increased of c-fos/c-jun expression levels in the cerebral cortex. These results suggest that MeHg neurotoxicity might be a greater hazard than that associated with PCB, but PCB may augment the neurobehavioral deficits caused by increased levels of mercury exposure. The simultaneous intake of selenium might have a protective effect on Hg accumulation in the body, and vitamin C might protect mice against the toxic effects of PCBs. However, the protective role of Se and vitamin C is very limited for multiple-agent pollution. Immediately early genes in the brain response to contaminated rice might be dependent on interaction among NO, NO synthase (NOS), SOD and reduced glutathione (GSH). We should be alert to mental health problems in human beings when any kind of Hg- and PCB-polluted food is

  12. Acute embryotoxic effects but no long-term reproductive effects of in ovo methylmercury exposure in zebra finches (Taeniopygia guttata).

    PubMed

    Yu, Maria S; Eng, Margaret L; Williams, Tony D; Basu, Niladri; Elliott, John E

    2016-06-01

    Mercury bioaccumulates in terrestrial ecosystems as methylmercury (MeHg), yet little is known about its effects on terrestrial organisms, including songbirds. The authors used a model songbird species, the zebra finch (Taeniopygia guttata), to assess short-term embryotoxic effects of in ovo MeHg exposure on hatching success and posthatching growth and nestling survival, as well as longer-term effects on mating behavior and reproduction. Egg treatment groups included a low-MeHg dose of 0.2 μg Hg g(-1) egg (n = 36), a high-MeHg dose of 3.2 μg Hg g(-1) egg (n = 49), and a control (n = 34). Doses were dissolved in nanopure filtered water and injected into the albumen on the day eggs showed signs of viability (3 d incubation). In ovo exposure to MeHg significantly reduced hatching success (53% in the high-MeHg dose group vs 94% in vehicle controls). Among hatched chicks, however, no effects of MeHg on growth, hematological variables, or nestling survival were detected. While the in ovo injection method resulted in a dose-dependent pattern of MeHg concentrations in blood of surviving chicks at 15 d and 30 d posthatching, there was evidence of rapid excretion of MeHg with nestling age during that growth period. At reproductive maturity (90 d of age), no long-term effects of in ovo exposure to MeHg on female mating behavior, reproductive effort (egg or clutch size), or growth and survivorship of offspring were observed. Environ Toxicol Chem 2016;35:1534-1540. © 2015 SETAC. PMID:26573953

  13. Methylmercury Exposure during Early Xenopus laevis Development Affects Cell Proliferation and Death but not Neural Progenitor Specification

    PubMed Central

    Huyck, Ryan W.; Nagarkar, Maitreyi; Olsen, Nina; Clamons, Samuel E.; Saha, Margaret S.

    2015-01-01

    Methylmercury (MeHg) is a widespread environmental toxin that preferentially and adversely affects developing organisms. To investigate the impact of MeHg toxicity on the formation of the vertebrate nervous system at physiologically relevant concentrations, we designed a graded phenotype scale for evaluating Xenopus laevis embryos exposed to MeHg in solution. Embryos displayed a range of abnormalities in response to MeHg, particularly in brain development, which is influenced by both MeHg concentration and the number of embryos per ml of exposure solution. A TC50 of ~50 μg/l and LC50 of ~100 μg/l were found when maintaining embryos at a density of one per ml, and both increased with increasing embryo density. In situ hybridization and microarray analysis showed no significant change in expression of early neural patterning genes including sox2, en2, or delta; however a noticeable decrease was observed in the terminal neural differentiation genes GAD and xGAT, but not xVGlut. PCNA, a marker for proliferating cells, was negatively correlated with MeHg dose, with a significant reduction in cell number in the forebrain and spinal cord of exposed embryos by tadpole stages. Conversely, the number of apoptotic cells in neural regions detected by a TUNEL (terminal deoxynucleotidyl transferase dUTP nick end labeling) assay was significantly increased. These results provide evidence that disruption of embryonic neural development by MeHg may not be directly due to a loss of neural progenitor specification and gene transcription, but to a more general decrease in cell proliferation and increase in cell death throughout the developing nervous system. PMID:25496965

  14. Methylmercury exposure affects motor performance of a riverine population of the Tapajós river, Brazilian Amazon.

    PubMed

    Dolbec, J; Mergler, D; Sousa Passos, C J; Sousa de Morais, S; Lebel, J

    2000-04-01

    . Although dose-effect relationships were observed in this cross-sectional study, they may reflect higher exposure levels in the past. The findings of this study demonstrated neurobehavioral manifestations of subtle neurotoxic effects on motor functions, associated with low-level methylmercury exposure. PMID:10787135

  15. Prenatal exposure to methylmercury and LCPUFA in relation to birth weight

    PubMed Central

    van Wijngaarden, E; Harrington, D; Kobrosly, R; Thurston, SW; O’Hara, T; McSorley, EM; Myers, GJ; Watson, GE; Shamlaye, CF; Strain, JJ; Davidson, PW

    2014-01-01

    Background Epidemiologic studies have been inconclusive regarding the impact of co-exposure to long chain polyunsaturated fatty acids (LCPUFA) and methyl mercury (MeHg) from fish consumption during pregnancy on measures of fetal development. Objectives We evaluated the association between birth weight and prenatal maternal LCPUFA status and MeHg exposure in the Republic of Seychelles. Methods We measured LCPUFA in maternal whole blood collected at 28 weeks of gestation and following delivery, and MeHg in maternal hair obtained at delivery. There were 230 births with complete data on birth weight and covariates. Multiple linear regression models controlled for infant sex, gestational age, maternal age, smoking during pregnancy, intrapartum weight gain, pre-pregnancy body mass index, maternal socioeconomic status, parity, gestational diabetes, and alcohol use during pregnancy. Results The average birth weight was 3,252 g (range 1654–4450) and the average gestational age was 39 weeks (range 34–41). Prenatal MeHg exposure and maternal LCPUFA status were not associated with birth weight. Infant sex and length of gestation were the only predictors, with male sex and increased gestational age consistently associated with greater birth weight. Conclusions These findings do not support a relationship between prenatal exposure to LCPUFA and/or MeHg from fish consumption and birth weight. PMID:24525104

  16. Prenatal methylmercury exposure hampers glutathione antioxidant system ontogenesis and causes long-lasting oxidative stress in the mouse brain

    SciTech Connect

    Stringari, James; Nunes, Adriana K.C.; Franco, Jeferson L.; Bohrer, Denise; Garcia, Solange C.; Dafre, Alcir L.; Milatovic, Dejan; Souza, Diogo O.; Rocha, Joao B.T.; Aschner, Michael; Farina, Marcelo

    2008-02-15

    During the perinatal period, the central nervous system (CNS) is extremely sensitive to metals, including methylmercury (MeHg). Although the mechanism(s) associated with MeHg-induced developmental neurotoxicity remains obscure, several studies point to the glutathione (GSH) antioxidant system as an important molecular target for this toxicant. To extend our recent findings of MeHg-induced GSH dyshomeostasis, the present study was designed to assess the developmental profile of the GSH antioxidant system in the mouse brain during the early postnatal period after in utero exposure to MeHg. Pregnant mice were exposed to different doses of MeHg (1, 3 and 10 mg/l, diluted in drinking water, ad libitum) during the gestational period. After delivery, pups were killed at different time points - postnatal days (PND) 1, 11 and 21 - and the whole brain was used for determining biochemical parameters related to the antioxidant GSH system, as well as mercury content and the levels of F{sub 2}-isoprostane. In control animals, cerebral GSH levels significantly increased over time during the early postnatal period; gestational exposure to MeHg caused a dose-dependent inhibition of this developmental event. Cerebral glutathione peroxidase (GPx) and glutathione reductase (GR) activities significantly increased over time during the early postnatal period in control animals; gestational MeHg exposure induced a dose-dependent inhibitory effect on both developmental phenomena. These adverse effects of prenatal MeHg exposure were corroborated by marked increases in cerebral F{sub 2}-isoprostanes levels at all time points. Significant negative correlations were found between F{sub 2}-isoprostanes and GSH, as well as between F{sub 2}-isoprostanes and GPx activity, suggesting that MeHg-induced disruption of the GSH system maturation is related to MeHg-induced increased lipid peroxidation in the pup brain. In utero MeHg exposure also caused a dose-dependent increase in the cerebral levels of

  17. Immunofluorescence Staining.

    PubMed

    Donaldson, Julie G

    2015-01-01

    This unit provides a protocol for indirect immunofluorescence, which is a method that provides information about the locations of specific molecules and the structure of the cell. Antibody molecules for a specific target molecule are exposed to the cell or tissue being investigated. The binding of these molecules is detected by incubating the sample with a secondary antibody specific for immunoglobulin molecules and conjugated to a fluorophore. This provides both a visible signal and amplification of the signal and the results are observed with a fluorescence microscope. This unit describes the widely used and powerful technique of localization of proteins in cells by immunofluorescence. The location can be determined by double labeling with an antibody directed against a protein of known location. The technique can be used as a supplement to immunolocalization by electron microscopy and subcellular fractionation. It allows not only identification of the antigen distribution in the cell but also a survey of the dynamic aspects of protein movements in the cell-on and off membranes, into and out of the nucleus, and through membrane traffic pathways. PMID:26621373

  18. Mercury Exposure in a Riverside Amazon Population, Brazil: A Study of the Ototoxicity of Methylmercury

    PubMed Central

    Hoshino, Ana; Pacheco-Ferreira, Heloisa; Sanches, Seisse Gabriela G.; Carvallo, Renata; Cardoso, Nathália; Perez, Maurício; Câmara, Volney de Magalhães

    2015-01-01

    Introduction Mercury poisoning causes hearing loss in humans and animals. Acute and long-term exposures produce irreversible peripheral and central auditory system damage, and mercury in its various forms of presentation in the environment is ototoxic. Objective We investigated the otoacoustic emissions responses in a riverside population exposed to environmental mercury by analyzing the inhibitory effect of the medial olivocochlear system (MOCS) on transient otoacoustic emissions (TEOAE). Methods The purpose of the research was to evaluate the entire community independently of variables of sex and age. All of the participants were born and lived in a riverside community. After otolaryngologic evaluation, participants were received tympanometry, evaluation of contralateral acoustic reflexes, pure tone audiometry, and recording of TEOAEs with nonlinear click stimulation. Hair samples were collect to measure mercury levels. Results There was no significant correlation between the inhibitory effect of the MOCS, age, and the level of mercury in the hair. Conclusions The pathophysiological effects of chronic exposure may be subtle and nonspecific and can have a long period of latency; therefore, it will be important to monitor the effects of mercury exposure in the central auditory system of the Amazon population over time. Longitudinal studies should be performed to determine whether the inhibitory effect of the MOCS on otoacoustic emissions can be an evaluation method and diagnostic tool in populations exposed to mercury. PMID:25992169

  19. Methylmercury exposure in a subsistence fishing community in Lake Chapala, Mexico: an ecological approach

    PubMed Central

    2010-01-01

    Background Elevated concentrations of mercury have been documented in fish in Lake Chapala in central Mexico, an area that is home to a large subsistence fishing community. However, neither the extent of human mercury exposure nor its sources and routes have been elucidated. Methods Total mercury concentrations were measured in samples of fish from Lake Chapala; in sections of sediment cores from the delta of Rio Lerma, the major tributary to the lake; and in a series of suspended-particle samples collected at sites from the mouth of the Lerma to mid-Lake. A cross-sectional survey of 92 women ranging in age from 18-45 years was conducted in three communities along the Lake to investigate the relationship between fish consumption and hair mercury concentrations among women of child-bearing age. Results Highest concentrations of mercury in fish samples were found in carp (mean 0.87 ppm). Sediment data suggest a pattern of moderate ongoing contamination. Analyses of particles filtered from the water column showed highest concentrations of mercury near the mouth of the Lerma. In the human study, 27.2% of women had >1 ppm hair mercury. On multivariable analysis, carp consumption and consumption of fish purchased or captured from Lake Chapala were both associated with significantly higher mean hair mercury concentrations. Conclusions Our preliminary data indicate that, despite a moderate level of contamination in recent sediments and suspended particulate matter, carp in Lake Chapala contain mercury concentrations of concern for local fish consumers. Consumption of carp appears to contribute significantly to body burden in this population. Further studies of the consequences of prenatal exposure for child neurodevelopment are being initiated. PMID:20064246

  20. Is susceptibility to prenatal methylmercury exposure from fish consumption non-homogeneous? Tree-structured analysis for the Seychelles Child Development Study.

    PubMed

    Huang, Li-Shan; Myers, Gary J; Davidson, Philip W; Cox, Christopher; Xiao, Fenyuan; Thurston, Sally W; Cernichiari, Elsa; Shamlaye, Conrad F; Sloane-Reeves, Jean; Georger, Lesley; Clarkson, Thomas W

    2007-11-01

    Studies of the association between prenatal methylmercury exposure from maternal fish consumption during pregnancy and neurodevelopmental test scores in the Seychelles Child Development Study have found no consistent pattern of associations through age 9 years. The analyses for the most recent 9-year data examined the population effects of prenatal exposure, but did not address the possibility of non-homogeneous susceptibility. This paper presents a regression tree approach: covariate effects are treated non-linearly and non-additively and non-homogeneous effects of prenatal methylmercury exposure are permitted among the covariate clusters identified by the regression tree. The approach allows us to address whether children in the lower or higher ends of the developmental spectrum differ in susceptibility to subtle exposure effects. Of 21 endpoints available at age 9 years, we chose the Weschler Full Scale IQ and its associated covariates to construct the regression tree. The prenatal mercury effect in each of the nine resulting clusters was assessed linearly and non-homogeneously. In addition we reanalyzed five other 9-year endpoints that in the linear analysis had a two-tailed p-value <0.2 for the effect of prenatal exposure. In this analysis, motor proficiency and activity level improved significantly with increasing MeHg for 53% of the children who had an average home environment. Motor proficiency significantly decreased with increasing prenatal MeHg exposure in 7% of the children whose home environment was below average. The regression tree results support previous analyses of outcomes in this cohort. However, this analysis raises the intriguing possibility that an effect may be non-homogeneous among children with different backgrounds and IQ levels. PMID:17942158

  1. The effects of prenatal methylmercury exposure on trace element and antioxidant levels in rats following 6-hydroxydopamine-induced neuronal insult.

    PubMed

    Mohamed Moosa, Zulfiah; Daniels, Willie M U; Mabandla, Musa V

    2014-06-01

    Methylmercury (MeHg) is a metal toxin found commonly in the environment. Studies have shown severe neurotoxic effects of MeHg poisoning especially during pregnancy where it crosses the foetoplacental and the blood brain barrier of the foetus leading to neurodevelopmental deficits in the offspring. These deficits may predispose offspring to neurodegenerative diseases later in life. In this study we investigated the effects of prenatal methylmercury exposure (2.5 mg/L in drinking water from GND 1-GND 21) on the trace element status in the brain of adolescent offspring (PND 28). Total antioxidant capacity (TAC) was measured in their blood plasma. In a separate group of animals that was also exposed prenatally to MeHg, 6-hydroydopamine (6-OHDA) was administered at PND 60 as a model of neuronal insult. Trace element and TAC levels were compared before and after 6-OHDA exposure. Prenatal MeHg treatment alone resulted in significantly higher concentrations of zinc, copper, manganese and selenium in the brain of offspring at PND 28 (p < 0.05), when compared to controls. In contrast, brain iron levels in MeHg-exposed adolescent offspring were significantly lower than their controls (p < 0.05). Following 6-OHDA exposure, the levels of iron, zinc, copper and manganese were increased compared to sham-lesioned offspring (p < 0.05). Prenatal MeHg exposure further increased these trace element levels thereby promoting toxicity (p < 0.05). Total antioxidant capacity was not significantly different in MeHg and control groups prior to lesion. However, following 6-OHDA administration, MeHg-exposed animals had a significantly lower TAC than that of controls (p < 0.05). Brain TAC levels were higher in adult male rats than in female rats during adolescence however male rats that had been exposed to MeHg in utero failed to show this increase at PND 74. Prenatal MeHg exposure results in trace element dyshomeostasis in the brain of offspring and reduces total

  2. Methylmercury Poisoning in Iraq

    ERIC Educational Resources Information Center

    Bakir, F.; And Others

    1973-01-01

    Discusses incidence of methylmercury poisoning throughout the world with increasing industrial and agricultural use of mercury compounds. Describes recent epidemic in Iraq resulting from use of wheat treated with methylmercurial fungicide. New data are presented on the toxicity of methylmercury and its metabolic fate in the human body. (JR)

  3. Prenatal Organochlorine and Methylmercury Exposure and Memory and Learning in School-Age Children in Communities Near the New Bedford Harbor Superfund Site, Massachusetts

    PubMed Central

    Orenstein, Sara T.C.; Thurston, Sally W.; Bellinger, David C.; Schwartz, Joel D.; Amarasiriwardena, Chitra J.; Altshul, Larisa M.

    2014-01-01

    Background: Polychlorinated biphenyls (PCBs), organochlorine pesticides, and methylmercury (MeHg) are environmentally persistent with adverse effects on neurodevelopment. However, especially among populations with commonly experienced low levels of exposure, research on neurodevelopmental effects of these toxicants has produced conflicting results. Objectives: We assessed the association of low-level prenatal exposure to these contaminants with memory and learning. Methods: We studied 393 children, born between 1993 and 1998 to mothers residing near a PCB-contaminated harbor in New Bedford, Massachusetts. Cord serum PCB, DDE (dichlorodiphenyldichloroethylene), and maternal peripartum hair mercury (Hg) levels were measured to estimate prenatal exposure. Memory and learning were assessed at 8 years of age (range, 7–11 years) using the Wide Range Assessment of Memory and Learning (WRAML), age-standardized to a mean ± SD of 100 ± 15. Associations with each WRAML index—Visual Memory, Verbal Memory, and Learning—were examined with multivariable linear regression, controlling for potential confounders. Results: Although cord serum PCB levels were low (sum of four PCBs: mean, 0.3 ng/g serum; range, 0.01–4.4), hair Hg levels were typical of the U.S. fish-eating population (mean, 0.6 μg/g; range, 0.3–5.1). In multivariable models, each microgram per gram increase in hair Hg was associated with, on average, decrements of –2.8 on Visual Memory (95% CI: –5.0, –0.6, p = 0.01), –2.2 on Learning (95% CI: –4.6, 0.2, p = 0.08), and –1.7 on Verbal Memory (95% CI: –3.9, 0.6, p = 0.14). There were no significant adverse associations of PCBs or DDE with WRAML indices. Conclusions: These results support an adverse relationship between low-level prenatal MeHg exposure and childhood memory and learning, particularly visual memory. Citation: Orenstein ST, Thurston SW, Bellinger DC, Schwartz JD, Amarasiriwardena CJ, Altshul LM, Korrick SA. 2014. Prenatal

  4. GLIA AND METHYLMERCURY NEUROTOXICITY

    PubMed Central

    Ni, Mingwei; Li, Xin; Rocha, João B. T.; Farina, Marcelo; Aschner, Michael

    2014-01-01

    Methylmercury (MeHg) is a global environmental pollutant with significant adverse effects on human health. As the major target of MeHg, the central nervous system (CNS) exhibits the most recognizable poisoning symptoms. The role of the two major nonneuronal cell types, astrocytes and microglia, in response to MeHg exposure was recently compared. These two cell types share several common features in MeHg toxicity, but interestingly, these cells types also exhibit distinct response kinetics, indicating a cell-specific role in mediating MeHg-induced neurotoxicity. The aim of this study was to review the most recent literature and summarize key features of glial responses to this organometal. PMID:22852858

  5. Methylmercury: a new look at the risks.

    PubMed Central

    Mahaffey, K R

    1999-01-01

    In the US, exposure to methylmercury, a neurotoxin, occurs primarily through consumption of fish. Data from recent studies assessing the health impact of methylmercury exposure due to consumption of fish and other sources in the aquatic food web (shellfish, crustacea, and marine mammals) suggest adverse effects at levels previously considered safe. There is substantial variation in human methylmercury exposure based on differences in the frequency and amount of fish consumed and in the fish's mercury concentration. Although virtually all fish and other seafood contain at least trace amounts of methylmercury, large predatory fish species have the highest concentrations. Concerns have been expressed about mercury exposure levels in the US, particularly among sensitive populations, and discussions are underway about the standards used by various federal agencies to protect the public. In the 1997 Mercury Study Report to Congress, the US Environmental Protection Agency summarized the current state of knowledge on methylmercury's effects on the health of humans and wildlife; sources of mercury; and how mercury is distributed in the environment. This article summarizes some of the major findings in the Report to Congress and identifies issues of concern to the public health community. Images p396-a p397-a p399-a p406-a p408-a p410-a PMID:10590759

  6. Associations of Baroreflex Sensitivity, Heart Rate Variability, and Initial Orthostatic Hypotension with Prenatal and Recent Postnatal Methylmercury Exposure in the Seychelles Child Development Study at Age 19 Years

    PubMed Central

    Périard, Daniel; Beqiraj, Bujar; Hayoz, Daniel; Viswanathan, Bharathi; Evans, Katie; Thurston, Sally W.; Davidson, Philip W.; Myers, Gary J.; Bovet, Pascal

    2015-01-01

    Background: A few studies have suggested an association between prenatal exposure to methylmercury and decreased heart rate variability (HRV) related to autonomic heart function, but no study has examined this association using baroreflex sensitivity (BRS). In this study we assessed the distribution of BRS and immediate orthostatic hypotension (IOH) in young Seychellois adults and their associations with exposure to prenatal and recent postnatal methylmercury. Methods: Subjects in theSeychelles Child Development Study (SCDS) main cohort were evaluated at age 19 years. Non-invasive beat-to-beat blood pressure (BP) monitoring (Finapres, Ohmeda) was performed at rest and during active standing in 95 consecutive subjects. Recent postnatal mercury exposure was measured in subjects’ hair at the age of 19 years and prenatal exposure in maternal hair grown during pregnancy. BRS was estimated by sequence analysis to identify spontaneous ascending and descending BP ramps. HRV was estimated by the following markers: PNN50 (relative numbers of normal-to-normal intervals which are shorter by more than 50 ms than the immediately following normal-to-normal intervals); rMSSD (root mean of the squared sum of successive interval differences); LF/HF (low frequency/high frequency component ratio); ratio of the mean expiratory/inspiratory RR intervals (EI ratio); and the ratio between the longest RR interval 30 s after active standing and the shortest RR interval at 15 s (Max30/Min15). IOH was estimated by the deepest BP fall within the first 15 s after active standing up. Results: Prenatal MeHg exposures were similar in boys and girls (6.7 ± 4.3, 6.7 ± 3.8 ng/g) but recent postnatal mercury levels were higher in males than females (11.2 ± 5.8 vs 7.9 ± 4.3 ng/g, p = 0.003). Markers of autonomic heart rate control were within the normal range (BRS: 24.8 ± 7 ms/mm Hg, PNN50: 24.9 ± 6.8%, rMSSD: 68 ± 22, LF/HF: 0.61 ± 0.28) in both sexes. After standing, 51.4% of subjects had a

  7. Inhibition of the Rho/ROCK pathway prevents neuronal degeneration in vitro and in vivo following methylmercury exposure

    SciTech Connect

    Fujimura, Masatake; Usuki, Fusako; Kawamura, Miwako; Izumo, Shuji

    2011-01-01

    Methylmercury (MeHg) is an environmental neurotoxicant which induces neuropathological changes in both the central nervous and peripheral sensory nervous systems. Our recent study demonstrated that down-regulation of Ras-related C3 botulinum toxin substrate 1 (Rac1), which is known to promote neuritic extension, preceded MeHg-induced damage in cultured cortical neurons, suggesting that MeHg-mediated axonal degeneration is due to the disturbance of neuritic extension. Therefore we hypothesized that MeHg-induced axonal degeneration might be caused by neuritic extension/retraction incoordination. This idea brought our attention to the Ras homolog gene (Rho)/Rho-associated coiled coil-forming protein kinase (ROCK) pathway because it has been known to be associated with the development of axon and apoptotic neuronal cell death. Here we show that inhibition of the Rho/ROCK pathway prevents MeHg-intoxication both in vitro and in vivo. A Rho inhibitor, C3 toxin, and 2 ROCK inhibitors, Fasudil and Y-27632, significantly protected against MeHg-induced axonal degeneration and apoptotic neuronal cell death in cultured cortical neuronal cells exposed to 100 nM MeHg for 3 days. Furthermore, Fasudil partially prevented the loss of large pale neurons in dorsal root ganglia, axonal degeneration in dorsal spinal root nerves, and vacuolar degeneration in the dorsal columns of the spinal cord in MeHg-intoxicated model rats (20 ppm MeHg in drinking water for 28 days). Hind limb crossing sign, a characteristic MeHg-intoxicated sign, was significantly suppressed in this model. The results suggest that inhibition of the Rho/ROCK pathway rescues MeHg-mediated neuritic extension/retraction incoordination and is effective for the prevention of MeHg-induced axonal degeneration and apoptotic neuronal cell death.

  8. Low level postnatal methylmercury exposure in vivo alters developmental forms of short-term synaptic plasticity in the visual cortex of rat

    SciTech Connect

    Dasari, Sameera; Yuan, Yukun

    2009-11-01

    Methylmercury (MeHg) has been previously shown to affect neurotransmitter release. Short-term synaptic plasticity (STP) is primarily related to changes in the probability of neurotransmitter release. To determine if MeHg affects STP development, we examined STP forms in the visual cortex of rat following in vivo MeHg exposure. Neonatal rats received 0 (0.9% NaCl), 0.75 or 1.5 mg/kg/day MeHg subcutaneously for 15 or 30 days beginning on postnatal day 5, after which visual cortical slices were prepared for field potential recordings. In slices prepared from rats treated with vehicle, field excitatory postsynaptic potentials (fEPSPs) evoked by paired-pulse stimulation at 20-200 ms inter-stimulus intervals showed a depression (PPD) of the second fEPSP (fEPSP2). PPD was also seen in slices prepared from rats after 15 day treatment with 0.75 or 1.5 mg/kg/day MeHg. However, longer duration treatment (30 days) with either dose of MeHg resulted in paired-pulse facilitation (PPF) of fEPSP2 in the majority of slices examined. PPF remained observable in slices prepared from animals in which MeHg exposure had been terminated for 30 days after completion of the initial 30 day MeHg treatment, whereas slices from control animals still showed PPD. MeHg did not cause any frequency- or region-preferential effect on STP. Manipulations of [Ca{sup 2+}]{sub e} or application of the GABA{sub A} receptor antagonist bicuculline could alter the strength and polarity of MeHg-induced changes in STP. Thus, these data suggest that low level postnatal MeHg exposure interferes with the developmental transformation of STP in the visual cortex, which is a long-lasting effect.

  9. Low level postnatal methylmercury exposure in vivo alters developmental forms of short-term synaptic plasticity in the visual cortex of rat

    PubMed Central

    Dasari, Sameera; Yuan, Yukun

    2009-01-01

    Methylmercury (MeHg) has been previously shown to affect neurotransmitter release. Short-term synaptic plasticity (STP) is primarily related to changes in the probability of neurotransmitter release. To determine if MeHg affects STP development, we examined STP forms in the visual cortex of rat following in vivo MeHg exposure. Neonatal rats received 0 (0.9% NaCl), 0.75 or 1.5 mg/kg/day MeHg subcutaneously for 15 or 30 days beginning on postnatal day 5, after which visual cortical slices were prepared for field potential recordings. In slices prepared from rats treated with vehicle, field excitatory postsynaptic potentials (fEPSPs) evoked by paired-pulse stimulation at 20 - 200 ms inter-stimulus intervals showed a depression (PPD) of the second fEPSP (fEPSP2). PPD was also seen in slices prepared from rats after 15 day treatment with 0.75 or 1.5 mg/kg/day MeHg. However, longer duration treatment (30 days) with either dose of MeHg resulted in paired-pulse facilitation (PPF) of fEPSP2 in the majority of slices examined. PPF remained observable in slices prepared from animals in which MeHg exposure had been terminated for 30 days after completion of the initial 30 day MeHg treatment, whereas slices from control animals still showed PPD. MeHg did not cause any frequency- or region-preferential effect on STP. Manipulations of [Ca2+]e or application of the GABAA receptor antagonist bicuculline could alter the strength and polarity of MeHg-induced changes in STP. Thus, these data suggest that low level postnatal MeHg exposure interferes with the developmental transformation of STP in the visual cortex, which is a long-lasting effect. PMID:19664649

  10. Effects of methylmercury exposure on glutathione metabolism, oxidative stress, and chromosomal damage in captive-reared common loon (Gavia immer) chicks

    USGS Publications Warehouse

    Kenow, K.P.; Hoffman, D.J.; Hines, R.K.; Meyer, M.W.; Bickham, J.W.; Matson, C.W.; Stebbins, K.R.; Montagna, P.; Elfessi, A.

    2008-01-01

    We quantified the level of dietary mercury (Hg), delivered as methylmercury chloride (CH3HgCl), associated with negative effects on organ and plasma biochemistries related to glutathione (GSH) metabolism and oxidative stress, and chromosomal damage in captive-reared common loon (Gavia immer) chicks reared from hatch to 105 days. Mercury-associated effects related to oxidative stress and altered glutathione metabolism occurred at 1.2 :g Hg/g and 0.4 :g Hg/g, an ecologically relevant dietary mercury level, but not at 0.08 :g Hg/g. Among the variables that contributed most to dissimilarities in tissue chemistries between control and treatment groups were increased levels of oxidized glutathione (GSSG), GSH peroxidase, and the ratio of GSSG to GSH in brain tissue; increased levels of hepatic GSH; and decreased levels of hepatic glucose-6-phosphate dehydrogenase (G-6-PDH). Our results also suggest that chronic exposure to environmentally relevant dietary Hg levels did not result in statistically significant somatic chromosomal damage in common loon chicks. Oxidative stress and altered glutathione metabolism were evident in common loon chicks exposed to >0.4 :g Hg as CH3HgCl per gram wet food intake.

  11. Associations between Prenatal and Recent Postnatal Methylmercury Exposure and Auditory Function at age 19 years in the Seychelles Child Development Study

    PubMed Central

    Orlando, Mark S.; Dziorny, Adam C.; Harrington, Donald; Love, Tanzy; Shamlaye, Conrad F.; Watson, Gene E.; van Wijngaarden, Edwin; Davidson, Philip W.; Myers, Gary J.

    2014-01-01

    Objectives To determine if prenatal or recent postnatal methylmercury (MeHg) exposure from consuming ocean fish and seafood is associated with auditory deficits in young adults. Some investigators have reported adverse associations while others have found no associations. Ocean fish is an important nutrient source for billions of people around the world. Consequently, determining if there is an adverse association with objective auditory measures is important in assessing whether a risk is present or not. Design The peripheral and central auditory function of 534 subjects in the Seychelles Child Development Study (SCDS) Main Cohort was examined at age 19 years. The auditory test battery included standard pure-tone audiometry, tympanometry, Auditory Brainstem Response (ABR) latencies, and both click-evoked and distortion-product Otoacoustic Emissions (OAE). Associations with MeHg were evaluated with multiple linear regression models, adjusting for sex, recent postnatal MeHg exposure, and hearing loss. Results Bilateral hearing loss (defined as a mean pure-tone threshold of greater than 25 dB) was present in 1.1% of the subjects and was not associated with prenatal or recent postnatal MeHg exposure. As expected, absolute and interwave ABR latencies were shorter for women as compared to men, as the stimulus presentation rate decreased from 69.9 to 19.9 clicks/sec and as the stimulus intensity increased from 60 to 80 dBnHL. Similarly, larger OAE amplitudes were elicited in women as compared to men and in the right ears as compared to the left. There was no association of prenatal MeHg exposure with hearing loss, ABR absolute and interwave latencies or OAE amplitudes. As recent postnatal MeHg increased, some associations were found with a few ABR absolute and interwave latencies and a few OAE amplitudes. However, the direction of these associations was inconsistent. As recent postnatal MeHg levels increased the wave I absolute latencies were shorter at 80 dBnHL for all

  12. Low-level exposure to methylmercury modifies muscarinic cholinergic receptor binding characteristics in rat brain and lymphocytes: physiologic implications and new opportunities in biologic monitoring.

    PubMed Central

    Coccini, T; Randine, G; Candura, S M; Nappi, R E; Prockop, L D; Manzo, L

    2000-01-01

    Methylmercury (MeHg) affects several parameters of cholinergic function. These alterations are thought to play a role in MeHg neurotoxicity. In vitro experiments have indicated that MeHg acts as a strong competitive inhibitor of radioligand binding to muscarinic cholinergic receptors (mAChRs) in rat brain. Furthermore, rat brain mAChRs share several pharmacologic characteristics of similar receptors present on lymphocytes. Using the muscarinic antagonist [(3)H]quinuclidinyl benzilate (QNB) to label receptors, we investigated the in vivo interactions of MeHg with rat brain mAChRs. We also investigated whether MeHg-induced central mAChR changes are reflected by similar alterations in splenic lymphocytes. Exposure to low doses of MeHg--0.5 or 2 mg/kg/day in drinking water--for 16 days significantly increased (20-44% of control) mAChRs density (B(max)) in the hippocampus and cerebellum without affecting receptor affinity (K(d)). The effect of MeHg did not occur immediately; it was not apparent until 2 weeks after the termination of treatment. No significant changes in [(3)H]QNB binding were observed in the cerebral cortex. In splenic lymphocytes, mAChR density was remarkably increased (95-198% of control) by day 14 of MeHg exposure and remained enhanced 14 days after the cessation of treatment. These results suggest up-regulation of mAChRs in selected brain regions (hippocampus and cerebellum) after prolonged low-level ingestion of MeHg in rats. These cerebral effects are delayed in onset and are preceded by a marked increase in density of mAChRs on lymphocytes. In chronic MeHg exposure, peripheral lymphocytes may represent a sensitive target for the interaction of MeHg with mAChRs and, therefore, may be predictive indicators of later adaptive response involving cerebral mAChRs. Additionally, the effect of MeHg on lymphocyte mAChRs in vivo indicates that this receptor system should be investigated further as a possible target for MeHg immunotoxicity. Images Figure 1

  13. Implications of mercury concentrations in umbilical cord tissue in relation to maternal hair segments as biomarkers for prenatal exposure to methylmercury.

    PubMed

    Sakamoto, Mineshi; Murata, Katsuyuki; Domingo, José L; Yamamoto, Megumi; Oliveira, Ricardo B; Kawakami, Shoichi; Nakamura, Masaaki

    2016-08-01

    In this study, we investigated how mercury (Hg) concentrations in umbilical cord tissue are correlated with those in biomarkers for prenatal exposure to methylmercury (MeHg). Total Hg (T-Hg) concentrations were measured in 54 mother-child paired samples of maternal blood, umbilical cord tissue, cord blood, and maternal hair segments (1-cm incremental segments from the scalp) collected at parturition. MeHg concentrations were also measured in the cord tissue. Median T-Hg and MeHg concentrations in cord tissue on a dry-weight basis (d.w.) were 62.2ng/g and 56.7ng/g, respectively. Proportions of MeHg to T-Hg were approximately 95%. Both T-Hg and MeHg in cord tissue (d.w.) showed better correlations with T-Hg in cord blood than did T-Hg in cord tissue on a wet-weight basis (w.w.). Median T-Hg concentrations in maternal blood, cord blood, and maternal hair (0-1cm from the scalp) were 3.79ng/g, 7.26ng/g, and 1.35 μg/g, respectively. Median T-Hg concentration in cord blood was 1.92 times higher than that in maternal blood. T-Hg in cord tissue (d.w.) showed a strong correlation with that in cord blood (r=0.912, p<0.01). Among the hair segments, T-Hg in cord tissue (d.w.) showed the strongest correlation (r=0.854, p<0.01) with that in maternal hair at 0-1cm from the scalp, reflecting growth for approximately 1 month before parturition. Based on the present results, T-Hg and MeHg concentrations in cord tissue may be useful biomarkers for prenatal MeHg exposure of the fetus, especially reflecting the maternal MeHg body burden during late gestation. The conversion factors for T-Hg and MeHg concentrations in cord tissue (d.w.) to T-Hg concentrations in maternal hair (0-1cm from the scalp) were calculated to be 22.37 and 24.09, respectively. This information will be useful for evaluating maternal MeHg exposure levels in retrospective studies using preserved umbilical cord tissue. PMID:27156841

  14. Methylmercury and Pregnancy

    MedlinePlus

    ... king crab, shrimp), or canned fish (including light tuna). Fish sticks and fast-food fish are likely ... with lower levels of methylmercury. Canned albacore (white) tuna and fresh tuna steaks typically have higher mercury ...

  15. Somatosensory Psychophysical Losses in Inhabitants of Riverside Communities of the Tapajós River Basin, Amazon, Brazil: Exposure to Methylmercury Is Possibly Involved

    PubMed Central

    Khoury, Eliana Dirce Torres; Souza, Givago da Silva; da Costa, Carlos Araújo; de Araújo, Amélia Ayako Kamogari; de Oliveira, Cláudia Simone Baltazar; Silveira, Luiz Carlos de Lima; Pinheiro, Maria da Conceição Nascimento

    2015-01-01

    The purpose of this work was to evaluate the somatosensory system of methylmercury-exposed inhabitants living in the communities of the Tapajós river basin by using psychophysical tests and to compare with measurements performed in inhabitants of the Tocantins river basin. We studied 108 subjects from Barreiras and São Luiz do Tapajós, two communities of the Tapajós river basin, State of Pará, Amazon, Brazil, aged 13–53 years old. Mercury analysis was performed in head hair samples weighting 0.1–0.2 g by using atomic absorption spectrometry. Three somatosensory psychophysical tests were performed: tactile sensation threshold, vibration sensation duration, and two-point discrimination. Semmes-Weinstein 20 monofilaments with different diameters were used to test the tactile sensation in the lower lip, right and left breasts, right and left index fingers, and right and left hallux. The threshold was the thinner monofilament perceived by the subject. Vibration sensation was investigated using a 128 Hz diapason applied to the sternum, right and left radial sides of the wrist, and right and left outer malleoli. Two trials were performed at each place. A stopwatch recorded the vibration sensation duration. The two-point discrimination test was performed using a two-point discriminator. Head hair mercury concentration was significantly higher in mercury-exposed inhabitants of Tapajós than in non-exposed inhabitants of Tocantins (p < 0.01). When all subjects were divided in two groups independently of age—mercury-exposed and non-exposed—the following results were found: tactile sensation thresholds in mercury-exposed subjects were higher than in non-exposed subjects at all body parts, except at the left chest; vibration sensation durations were shorter in mercury-exposed than in non-exposed subjects, at all locations except in the upper sternum; two-point discrimination thresholds were higher in mercury-exposed than in non-exposed subjects at all body parts

  16. Gender differential effects of developmental exposure to methyl-mercury, polychlorinated biphenyls 126 or 153, or its combinations on motor activity and coordination.

    PubMed

    Cauli, Omar; Piedrafita, Blanca; Llansola, Marta; Felipo, Vicente

    2013-09-01

    Polychlorinated biphenyls (PCBs) and methylmercury (MeHg) are persistent organic pollutants accumulating in the food chain. Pre- and neonatal exposure to these neurotoxicants may affect brain development and lead to long-lasting alterations in cerebral function, which can result in motor alterations in youth and/or adulthood. Some neurotoxicants induce gender specific effects. The aims of the present work were to: (1) assess the effects of developmental exposure to MeHg, PCB 153 or PCB 126 on spontaneous locomotor and vertical activity and motor coordination when the rats are 2-month old; (2) assess whether perinatal exposure to combinations of MeHg with PCB153 or PCB126 alter the effects of the individual neurotoxicants; (3) follow the progression of motor alterations when the rats are 3-, 5- and 7-month old; (4) assess if the effects are similar or different in males and females. Pregnant rats were treated with MeHg (0.5mg/kgday); PCB126 (100ng/kgday) or PCB153 (1mg/kgday) or with combinations of MeHg with each PCB, administered in food from gestational day 7 until weaning at post-natal day 21. PCB 126 impaired motor coordination at 2 months in males but not in females. PCB 153 impaired coordination both in males and females. Combinations of MeHg with PCB153 or PCB126 did not affect motor coordination, indicating that MeHg counteracts the effects of the PBCs. The combination of MeHg and PCB153 induces hypolocomotion at 2 months but hyperactivity at 7 months while the individual compounds did not induce any effect. PCB126 induced gender selective effects, reducing locomotor activity at 2 months in females but not in males. The combination of MeHg and PCB126 behaves as PCB126 alone. All compounds and combinations tested induce gender-selective alterations in vertical activity. The effects on locomotor and vertical activity change with age in the same rats. At 2 months all compounds and combinations reduce vertical activity in females but not in males. At 7 months

  17. Recent evidence from epidemiological studies on methylmercury toxicity.

    PubMed

    Murata, Katsuyuki; Yoshida, Minoru; Sakamoto, Mineshi; Iwai-Shimada, Miyuki; Yaginuma-Sakurai, Kozue; Tatsuta, Nozomi; Iwata, Toyoto; Karita, Kanae; Nakai, Kunihiko

    2011-09-01

    More than fifty years have passed since the outbreak of Minamata disease, and large-scale methylmercury poisoning due to industrial effluents or methylmercury-containing fungicide intoxication has scarcely happened in developed countries. On the other hand, widespread environmental mercury contamination has occurred in gold and mercury mining areas of developing countries. In this article, we provided an overview of recent studies addressing human health effects of methylmercury, which we searched using the PubMed of the US National Library of Medicine. The following suggestions were obtained for low-level methylmercury exposure: (1) In recent years, the proportion of human studies addressing methylmercury has tended to decrease. (2) Prenatal exposure to methylmercury through fish intake, even at low levels, adversely affects child development after adjusting for polychlorinated biphenyls and maternal fish intake during pregnancy, whereas maternal seafood intake has some benefits. (3) Long-term methylmercury exposure through consumption of fish such as bigeye tuna and swordfish may pose a potential risk of cardiac events involving sympathovagal imbalance. (4) In measuring methylmercury levels in preserved umbilical cord collected from inhabitants born in Minamata areas between 1945 and 1989, the elevated concentrations (≥1 mg/g) were observed mainly in inhabitants born between 1947 and 1968, and the peak coincided with the peak of acetaldehyde production in Minamata. (5) Since some developing countries appear to be in similar situations to Japan in the past, attention should be directed toward early recognition of a risky agent and precautions should be taken against it. PMID:21996768

  18. Pathological effects of in utero methylmercury exposure on the cerebellum of the golden hamster: early effects upon the neonatal cerebellar cortex-Part I

    SciTech Connect

    Reuhl, K.R.; Chang, L.W.; Townsend, J.W.

    1981-12-01

    Pregnant golden hamsters (Mesocricetus auratus) were given either a single dose of 10 mg methylmercury/kg on gestational day 10 or daily doses of 2 mg/kg on gestational days 10-15. Cerebella of experimental and control offspring were examined by light and electron microscopy during the first month of postnatal life. Degenerative changes, characterized by accumulations of lysosomes and areas of floccular cytoplasmic degradation, were frequently observed in neuroblasts of the external granular layer (EGL) as well as in more differentiated neural elements in the molecular and internal granular layers. Pyknotic nuclei were seen singly and in groups throughout the EGL of treated animals. Developing dendrites appeared particularly sensitive to methylmercury. Affected dendrites were swollen and packed with degenerating cytoplasmic material. Astrocytes and perivascular macrophages also contained large aggregates of irregular electron-opague debris, lysosomes, and large lipid droplets. Pathological alterations in the cerebellum were most pronounced during the first 15 days of postpartum life.

  19. Negative Confounding by Essential Fatty Acids in Methylmercury Neurotoxicity Associations

    PubMed Central

    Choi, Anna L; Mogensen, Ulla B.; Bjerve, Kristian S.; Debes, Frodi; Weihe, Pal; Grandjean, Philippe; Budtz-Jørgensen, Esben

    2014-01-01

    Background Methylmercury, a worldwide contaminant of fish and seafood, can cause adverse effects on the developing nervous system. However, long-chain n-3 polyunsaturated fatty acids in seafood provide beneficial effects on brain development. Negative confounding will likely result in underestimation of both mercury toxicity and nutrient benefits unless mutual adjustment is included in the analysis. Methods We examined these associations in 176 Faroese children, in whom prenatal methylmercury exposure was assessed from mercury concentrations in cord blood and maternal hair. The relative concentrations of fatty acids were determined in cord serum phospholipids. Neuropsychological performance in verbal, motor, attention, spatial, and memory functions was assessed at 7 years of age. Multiple regression and structural equation models (SEMs) were carried out to determine the confounder-adjusted associations with methylmercury exposure. Results A short delay recall (in percent change) in the California Verbal Learning Test (CVLT) was associated with a doubling of cord blood methylmercury (−18.9, 95% confidence interval [CI] = −36.3, −1.51). The association became stronger after the inclusion of fatty acid concentrations in the analysis (−22.0, 95% confidence interval [CI] = −39.4, −4.62). In structural equation models, poorer memory function (corresponding to a lower score in the learning trials and short delay recall in CVLT) was associated with a doubling of prenatal exposure to methylmercury after the inclusion of fatty acid concentrations in the analysis (−1.94, 95% CI = −3.39, −0.49). Conclusions Associations between prenatal exposure to methylmercury and neurobehavioral deficits in memory function at school age were strengthened after fatty acid adjustment, thus suggesting that n-3 fatty acids need to be included in analysis of similar studies to avoid underestimation of the associations with methylmercury exposure. PMID:24561639

  20. Adverse Effects of Methylmercury: Environmental Health Research Implications

    PubMed Central

    Grandjean, Philippe; Satoh, Hiroshi; Murata, Katsuyuki; Eto, Komyo

    2010-01-01

    Background The scientific discoveries of health risks resulting from methylmercury exposure began in 1865 describing ataxia, dysarthria, constriction of visual fields, impaired hearing, and sensory disturbance as symptoms of fatal methylmercury poisoning. Objective Our aim was to examine how knowledge and consensus on methylmercury toxicity have developed in order to identify problems of wider concern in research. Data sources and extraction We tracked key publications that reflected new insights into human methylmercury toxicity. From this evidence, we identified possible caveats of potential significance for environmental health research in general. Synthesis At first, methylmercury research was impaired by inappropriate attention to narrow case definitions and uncertain chemical speciation. It also ignored the link between ecotoxicity and human toxicity. As a result, serious delays affected the recognition of methylmercury as a cause of serious human poisonings in Minamata, Japan. Developmental neurotoxicity was first reported in 1952, but despite accumulating evidence, the vulnerability of the developing nervous system was not taken into account in risk assessment internationally until approximately 50 years later. Imprecision in exposure assessment and other forms of uncertainty tended to cause an underestimation of methylmercury toxicity and repeatedly led to calls for more research rather than prevention. Conclusions Coupled with legal and political rigidity that demanded convincing documentation before considering prevention and compensation, types of uncertainty that are common in environmental research delayed the scientific consensus and were used as an excuse for deferring corrective action. Symptoms of methylmercury toxicity, such as tunnel vision, forgetfulness, and lack of coordination, also seemed to affect environmental health research and its interpretation. PMID:20529764

  1. Methylmercury (MeHg)

    Integrated Risk Information System (IRIS)

    Methylmercury ( MeHg ) ; CASRN 22967 - 92 - 6 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarci

  2. Marine biogeochemistry: Methylmercury manufacture

    NASA Astrophysics Data System (ADS)

    Cossa, Daniel

    2013-10-01

    The neurotoxin methylmercury can accumulate in marine food webs, contaminating seafood. An analysis of the isotopic composition of fish in the North Pacific suggests that much of the mercury that enters the marine food web originates from low-oxygen subsurface waters.

  3. Immunofluorescence in dermatology.

    PubMed

    Chhabra, Seema; Minz, Ranjana Walker; Saikia, Biman

    2012-01-01

    Direct immunofluorescence (DIF) and indirect immunofluorescence (IIF) tests on skin biopsy are being done mostly in academic teaching hospitals. These tests provide a useful diagnostic aid to dermatologists. Immunohistology and serology can, in conjunction with histology, provide considerable help in delineation and diagnosis of various skin disorders as well as systemic diseases with skin involvement, e.g. systemic lupus erythematosus. Immunofluorescence (IF) studies have now become an invaluable supplement to clinical and histological examination in a variety of dermatological diseases. These skin diseases now include not only bullous and connective tissue disorders, vasculitides, and conditions such as lichen planus, but also the scaling dermatoses, notably psoriasis. In this review article, we share our experience of providing such a diagnostic facility for more than 30 years in a large tertiary care health center in North India and also help to outline the conditions, which can be diagnosed confidently, and others where IF can help in confirming a diagnosis or the immune component of the disease. The article also deals with handling of skin biopsy specimens and interpretation of biopsy findings on DIF and IIF examination. PMID:23075636

  4. Developmental exposure to polychlorinated biphenyls or methylmercury, but not to its combination, impairs the glutamate-nitric oxide-cyclic GMP pathway and learning in 3-month-old rats.

    PubMed

    Piedrafita, B; Erceg, S; Cauli, O; Felipo, V

    2008-07-17

    Prenatal exposure to polychlorinated biphenyls (PCBs) or methylmercury (MeHg) contaminated food may affect brain development, leading to long-term alterations in cognitive function. Both types of contaminants, PCBs and MeHg, are often found together contaminating food, especially fish in some polluted areas. Exposure to combinations of neurotoxicants may exert different effects on the developing nervous system than exposure to individual contaminants. Developmental exposure (during pregnancy and lactation) to PCB126 or PCB153 impairs learning ability when the rats are 3 months old. Impairment of learning seems to be a consequence of impairment of the function of the glutamate-nitric oxide (NO)-cGMP pathway in brain in vivo. The aims of the present work were 1) to assess whether perinatal exposure to MeHg also affects the function of the glutamate-NO-cGMP pathway in brain in vivo analyzed by in vivo brain microdialysis and/or the ability to learn the Y maze task when the rats are 3 months old, and 2) to assess whether perinatal exposure to combinations of MeHg with PCB153 or PCB126 potentiates, decreases or does not modify the effects of the individual neurotoxicants. Perinatal exposure to PCB126, PCB153 or MeHg impaired the function of the glutamate-NO-cGMP pathway in cerebellum and learning ability. However, co-exposure to PCB126+MeHg or PCB153+MeHg inhibits the impairment of the pathway or learning ability. These results support that the function of this pathway modulates learning of the Y maze task. Moreover, they show that co-exposure to these PCBs and MeHg does not exacerbate, but reduces the effects on the ability to learn this task. PMID:18556134

  5. Recognizing and Preventing Overexposure to Methylmercury from Fish and Seafood Consumption: Information for Physicians

    PubMed Central

    Silbernagel, Susan M.; Carpenter, David O.; Gilbert, Steven G.; Gochfeld, Michael; Groth, Edward; Hightower, Jane M.; Schiavone, Frederick M.

    2011-01-01

    Fish is a valuable source of nutrition, and many people would benefit from eating fish regularly. But some people eat a lot of fish, every day or several meals per week, and thus can run a significant risk of overexposure to methylmercury. Current advice regarding methylmercury from fish consumption is targeted to protect the developing brain and nervous system but adverse health effects are increasingly associated with adult chronic low-level methylmercury exposure. Manifestations of methylmercury poisoning are variable and may be difficult to detect unless one considers this specific diagnosis and does an appropriate test (blood or hair analysis). We provide information to physicians to recognize and prevent overexposure to methylmercury from fish and seafood consumption. Physicians are urged to ask patients if they eat fish: how often, how much, and what kinds. People who eat fish frequently (once a week or more often) and pregnant women are advised to choose low mercury fish. PMID:21785592

  6. ETHYLMERCURY: FORMATION IN PLANT TISSUES AND RELATION TO METHYLMERCURY FORMATION

    EPA Science Inventory

    Seedlings of the common dwarf garden pea, Pisum sativum, cv. Little Marvel, exposed to elemental mercury vapor formed both methylmercury and ethylmercury in all parts of the plant. Concentrations of both organomercury compounds fluctuated considerably over a 48-hour exposure peri...

  7. Methylmercury risk assessment issues

    SciTech Connect

    Lipfert, F.W.; Saroff, L.

    1996-07-01

    This paper reviews the general background of health risks associated with mercury (Hg), primarily methylmercury (MeHg), with a view towards application to advanced technologies that could reduce any contributions from coal combustion. The need for accurate assessment of such risks is discussed, since Hg is now widely dispersed in the environment and cannot easily be eliminated. The primary pathway of MeHg intake is through eating contaminated fish. The issues of concern include identification of critical health outcomes (various neurological indices) and their confounding factors, accurate assessment of MeHg intake rates, and appropriate use of dose-response functions. Ultimately, such information will be used to evaluate alternative coal combustion systems.

  8. Uptake of mercury by the hair of methylmercury-treated newborn mice

    SciTech Connect

    Shi, Chenyang; Lane, A.T.; Clarkson, T.W. )

    1990-04-01

    Human hair has unique advantages in monitoring environmental exposures to methyl-mercury. Using newborn Balb/c mice as a model system, the incorporation of methylmercury into the hair was studied and compared with methylmercury distributions in other tissues. Newborn mice were given intraperitoneal injections of {sup 203}Hg-labeled methylmercury at designated times according to hair growth stages of the mouse. Animals were sacrificed 2 days after dosing. Distribution of mercury in pelt and other tissues was measured. The level of mercury in pelt was found to correlate with hair growth. The amount of mercury in pelt peaked when hair growth was most rapid and the total amount of mercury in pelt was significantly higher than that in other tissues, constituting 40% of the whole body burden. However, when the hair ceased growing, the amount of mercury in pelt dramatically dropped to 4% of whole body burden and mercury concentrations in other tissues except brain were elevated. Autoradiographic studies with tritium-labeled methylmercury demonstrated that methylmercury concentrated in hair follicles in the skin. Within hair follicles and hairs, methylmercury accumulated in regions that are rich in high-sulfur proteins. The uptake of inorganic mercury (administered as HgCl{sub 2}) by pelt was also compared with that of methylmercury. The amount of inorganic mercury found in pelt was less than one-half that of methylmercury in animals with growing hair. Cessation of hair growth did not decrease the inorganic mercury level in pelt to the same extent as in the case of methylmercury.

  9. Mercury in women exposed to methylmercury through fish consumption, and in their newborn babies and breast milk

    SciTech Connect

    Skerfving, S.

    1988-10-01

    The presence of methylmercury in fish is a major environmental problem. During the major epidemics of methylmercury poisoning through sea food in Minamata in Japan, and through dressed seed in Iraq, there was a high prevalence of infants, who developed cerebral palsy. This was generally assumed to be due to intrauterine methylmercury poisoning, as it is well known, that methylmercury is transferred through the placenta into the fetus. There is also a possibility that exposure occurred through breast milk, as high levels of mercury in breast milk have been reported in mothers from Minamata. Information on the relationship between methylmercury exposure, mercury levels in blood of mothers and their babies, and levels in breast milk are reported here.

  10. Mental retardation and prenatal methylmercury toxicity

    SciTech Connect

    Trasande, L.; Schechter, C.B.; Haynes, K.A.; Landrigan, P.J.

    2006-03-15

    Methylmercury (MeHg) is a developmental neurotoxicant; exposure results principally from consumption of seafood contaminated by mercury (Hg). In this analysis, the burden of mental retardation (MR) associated with methylmercury exposure in the 2000 U.S. birth cohort is estimated, and the portion of this burden attributable to mercury (Hg) emissions from coal-fired power plants is identified. The aggregate loss in cognition associated with MeHg exposure in the 2000 U.S. birth cohort was estimated using two previously published dose-response models that relate increases in cord blood Hg concentrations with decrements in IQ. MeHg exposure was assumed not to be correlated with native cognitive ability. Previously published estimates were used to estimate economic costs of MR caused by MeHg. Downward shifts in IQ resulting from prenatal exposure to MeHg of anthropogenic origin are associated with 1,566 excess cases of MR annually (range: 376-14,293). This represents 3.2% of MR cases in the US (range: 0.8%-29.2%). The MR costs associated with decreases in IQ in these children amount to $2.0 billion/year (range: $0.5-17.9 billion). Hg from American power plants accounts for 231 of the excess MR cases year (range: 28-2,109), or 0.5% (range: 0.06%-4.3%) of all MR. These cases cost $289 million (range: $35 million-2.6 billion). Toxic injury to the fetal brain caused by Hg emitted from coal-fired power plants exacts a significant human and economic toll on American children.

  11. Methylmercury inhibits prolactin release in a cell line of pituitary origin

    PubMed Central

    Maués, L.A.L.; Macchi, B.M.; Crespo-López, M.E.; Nasciutti, L.E.; Picanço-Diniz, D.L.W.; Antunes-Rodrigues, J.; do Nascimento, J.L.M.

    2015-01-01

    Heavy metals, such as methylmercury, are key environmental pollutants that easily reach human beings by bioaccumulation through the food chain. Several reports have demonstrated that endocrine organs, and especially the pituitary gland, are potential targets for mercury accumulation; however, the effects on the regulation of hormonal release are unclear. It has been suggested that serum prolactin could represent a biomarker of heavy metal exposure. The aim of this study was to evaluate the effect of methylmercury on prolactin release and the role of the nitrergic system using prolactin secretory cells (the mammosomatotroph cell line, GH3B6). Exposure to methylmercury (0-100 μM) was cytotoxic in a time- and concentration-dependent manner, with an LC50 higher than described for cells of neuronal origin, suggesting GH3B6 cells have a relative resistance. Methylmercury (at exposures as low as 1 μM for 2 h) also decreased prolactin release. Interestingly, inhibition of nitric oxide synthase by N-nitro-L-arginine completely prevented the decrease in prolactin release without acute neurotoxic effects of methylmercury. These data indicate that the decrease in prolactin production occurs via activation of the nitrergic system and is an early effect of methylmercury in cells of pituitary origin. PMID:26108095

  12. Temporal Assessment of Methylmercury in an Endangered Pacific Seabird (Invited)

    NASA Astrophysics Data System (ADS)

    Vo, A. E.; Bank, M. S.; Shine, J. P.; Edwards, S. V.

    2010-12-01

    Methylmercury cycling in the Pacific Ocean has garnered significant attention in recent years, especially with regard to rising mercury emissions from Asia. Uncertainty exists over the extent to which mercury accumulation in biota may have resulted from increases in anthropogenic output over time. To address this, we assessed historical and recent mercury exposure in an endangered Pacific seabird, the Black-footed Albatross (Phoebastria nigripes), using feather samples from museum specimens spanning the past 130 years. We additionally analyzed stable isotopes of nitrogen (δ15N) and carbon (δ13C) to control for confounding factors of temporal change in trophic structure or diet. As a long-lived, wide-ranging, top marine predator and an endangered, keystone species in the North Pacific, the Black-footed Albatross comprises an ideal sentinel species for determining the effect of both global increases in mercury throughout the previous century and regional increases during the recent past on bioaccumulation and risk among avian wildlife. A significantly higher proportion of post-1940 samples contained above deleterious threshold levels (~40,000 ng/g) of methylmercury relative to pre-1940 samples, and mean concentrations were significantly higher in post-1990 than in pre-1990 samples. We also found increasingly higher amounts of (presumably curator-mediated) inorganic mercury contamination in older museum samples for the Black-footed Albatross as well as two non-pelagic comparison species, which informs future studies on bioaccumulation in museum specimens to analyze methylmercury rather than total mercury in all but recently collected specimens. Although complementary stable isotope data suggested no historic change in albatross trophic level, there was a significant change in δ13C signature over time. However, after controlling for these potential confounders, time significantly and positively associated with methylmercury exposure. Changes in methylmercury levels

  13. Clinical and epidemiological aspects of methylmercury poisoning.

    PubMed Central

    Bakir, F.; Rustam, H.; Tikriti, S.; Al-Damluji, S. F.; Shihristani, H.

    1980-01-01

    An opportunity to study the effects of methylmercury poisoning in humans was provided by the large outbreak in Iraq in 1971-2. In adults, poisoning resulted from the ingestion of home-made bread prepared from methylmercury-treated seed grain and there was a highly significant correlation between the amount of bread ingested and blood mercury levels. Poisoning in infants resulted either from prior exposure in utero or from suckling or both. Blood mercury levels were higher in infants and children than in adults. There was no increased incidence of congenital defects. Symptoms and signs of poisoning and histopathological changes were mainly confined to the CNS. Symptoms developed, on average, 1-2 months after exposure. In children there was mental retardation with delayed onset of speech and impaired motor, sensory and autonomic function. Severely affected children were blind and deaf. In adults, the clinical picture could be classified as 1, mild (mainly of sensory symptoms) 2, moderate (sensory symptoms accompanied by cerebellar signs) and 3, severe (gross ataxia with marked visual and hearing loss which, in some cases, progressed to akinetic mutism followed by coma). Grades 1 and 2 carried a better prognosis thant grade 3. Interference with transmission at the myoneural junction was found in 14% of patients studied. There was no evidence of peripheral nerve involvement per se and sensory symptoms may be of central origin. The clinical differences between the Iraqi and Japanese outbreaks may be a result, in part at least, of the severe, prolonged and continuous exposure which occurred in the latter outbreak. Improvement was observed among the mild and moderate group. Treatment with chelating agents, thiol resin, haemodialysis and exchange transfusion lowered blood mercury concentrations but produced no convincing clinical benefit. To be effective, treatment may need to be instituted soon after exposure. PMID:7383945

  14. Behavioral teratology of methylmercury in fish

    SciTech Connect

    Weis, P.; Weis, J.S.

    1994-12-31

    Embryos of the mummichog, Fundulus heteroclitus, were exposed to 2, 5, or 10 ug/l methylmercury throughout development. These are concentrations below those that can cause teratological effects. After hatching, larvae were maintained in clean sea water and tested for prey capture ability, using Artemia nauplii as prey. Individual fish larvae were provided with five brine shrimp and their capture times recorded. In all experiments, larvae that had been exposed to 10 ug/l methylmercury initially exhibited slower prey capture ability than the other groups. This is an indication of a subtle functional impairment due to the toxicant (``behavioral teratology``). However, the effect was transitory, and by about one week after hatching the prey capture of these larvae equaled that of the controls and the other treated groups. Growth of these larvae also equaled that of controls and the other groups. The embryonic exposure may have caused retardation of neurological development, which was subsequently compensated for, and therefore no permanent effects were produced. In the field, however, embryos exposed to such toxicants would probably continue to be exposed as larvae, and would not have the opportunity to recover from the effects, but rather might have them reinforced.

  15. Intervention study on cardiac autonomic nervous effects of methylmercury from seafood.

    PubMed

    Yaginuma-Sakurai, Kozue; Murata, Katsuyuki; Shimada, Miyuki; Nakai, Kunihiko; Kurokawa, Naoyuki; Kameo, Satomi; Satoh, Hiroshi

    2010-01-01

    To scrutinize whether the provisional tolerable weekly intake (PTWI, 3.4 microg/kg body weight/week) of methylmercury in Japan is safe for adults, we conducted an intervention study using heart rate variability (HRV) that has been considered to reflect cardiac events. Fifty-four healthy volunteers were recruited and divided into experimental and control groups. The experimental group was exposed to methylmercury at the PTWI level through consumption of bigeye tuna and swordfish for 14 weeks, and HRV parameters were compared between the two groups. In the experimental group, mean hair mercury levels, determined before and after the dietary methylmercury exposure and after 15-week wash-out period following the cessation of exposure, were 2.30, 8.76 and 4.90 microg/g, respectively. The sympathovagal balance index of HRV was significantly elevated after the exposure, and decreased to the baseline level at the end of this study. Still, such changes in HRV parameters were not found in the control group with a mean hair mercury level of around 2.1 microg/g. In conclusion, the PTWI does not appear to be safe for adult health, because methylmercury exposure from fish consumption induced a temporary sympathodominant state. Rather, long-term exposure to methylmercury may pose a potential risk for cardiac events involving sympathovagal imbalance among fish-consuming populations. PMID:19732823

  16. Mouse Cochlear Whole Mount Immunofluorescence

    PubMed Central

    Akil, Omar; Lustig, Lawrence R.

    2016-01-01

    This protocol comprises the entire process of immunofluorescence staining on mouse cochlea whole mount, starting from tissue preparation to the mounting of the tissue. This technique provides “three-dimensional” views of the stained components in order to determine the localization of a protein of interest in the tissue in its natural state and environment. PMID:27547786

  17. Neurotoxic actions of methylmercury on the primate visual system

    SciTech Connect

    Merigan, W.H.; Maurissen, J.P.J.; Weiss, B.; Eskin, T.; Lapham, L.W.

    1983-01-01

    Visual system consequences of exposure to methylmercury were studied in six adult, macaque monkeys. Visual field measures, visual thresholds, and morphological examination were used to determine the nature and possible reversibility of alterations in vision. Visual field constriction (especially in the inferior-nasal field) was an early and apparently reversible indicator of methylmercury intoxication. Such a field loss was found in the absence of either visual threeshold changes or morphologic alterations in visual cortex. More severe poisoning resulted in persistent field constriction, disruption of visual thresholds, and death. A single monkey showed a permanent, bilateral concentric constriction of visual fields. The locus of visual cortex pathology in this monkey corresponded to the projection of the peripheral visual field.

  18. Chronic methylmercurialism in the cat.

    PubMed

    Gruber, T A; Costigan, P; Wilkinson, G T; Seawright, A A

    1978-04-01

    The mercury levels in 69 muscle samples from fish weighing from 0.3 to 200 kg caught in Moreton Bay, Queensland, in the latter half of 1976 ranged from less than 10 to 2,030 ng/g. Mercury levels in blood samples from 53 humans and 100 dogs in Brisbane almost all contained less than 10 ng/ml while the level in 162 cats sampled ranged from less than 10 to 329 ng/ml. Chronic methylmercurialism developed in 2 cats dosed daily with methylmercury, bound to cysteine, at the rate of 0.6 mg/kg body weight for 74 and 77 days respectively. Terminal clinical signs included anorexia, weight loss, knuckling over at the carpus and tarsus, hypermetria initially involving the forelegs and later the hindlegs, sluggish reflexes, paresis involving all limbs, persistent crying, apparent blindness, tonic and clonic convulsions and salivation. Pathological changes were confined to the nervous system and included degeneration of neurones and perivascular cuffing in the cerebrocortical grey matter, focal atrophy of the granular layer, focal spongiosus of the molecular layer and degeneration and loss of Purkinje cells in the cerebellum and demyelination in the fibre tracts of the dorsal funiculus, mainly the fasciculus cuneatus and in the lateral and ventral corticospinal tracts. Terminal blood methylmercury levels were in excess of 18 microgram/ml, while brain methylmercury levels ranged from 21.0 to 28.4 microgram/g. The liver and kidney contained the highest total levels of mercury of 50 to 80 microgram/g, of which 23 to 37% was inorganic. PMID:687273

  19. Quantitative studies of immunofluorescent staining

    PubMed Central

    Wick, G.; Beutner, E. H.

    1970-01-01

    The antiperinuclear factor (APF) is found in a high percentage of sera from patients with rheumatoid arthritis. It can be demonstrated by direct immunofluorescence using the keratohyaline granules of human buccal mucosa as antigenic substrate. Mixing of some normal goat sera with an APF positive serum from a patient with rheumatoid arthritis resulted in an inhibition of the APF titre of the patient's serum. However, there was no clear cut correlation between the APF-positivity of normal goat sera and their inhibitory effect on the APF-reactivity of a human rheumatoid arthritis patient's serum. In reciprocal screening tests the human rheumatoid arthritis serum blocked only one of the APF-reactive goat sera. The reciprocal blocking activity of this goat serum and the patient's serum could be more exactly evaluated by the use of chessboard titrations in an indirect immunofluorescence blocking test. This test consisted of mixing equal volumes of serial dilutions of a goat serum and the patient's serum and subsequent examination of the mixtures for APF using an anti-human IgG conjugate and an anti-goat immunoglobulin conjugate, respectively. The results point to an antibody nature for the APF in preimmune, normal goat sera and to the value of chessboard titrations of this type in demonstrating the identity, non-identity, partial identity (or very close proximity of antigenic determinants) of the antibodies in different antisera which cannot be distinguished by their immunofluorescent staining patterns. ImagesFIG. 1FIG. 2 PMID:4913803

  20. Hormetic effect of methylmercury on Caenorhabditis elegans

    SciTech Connect

    Helmcke, Kirsten J. Aschner, Michael

    2010-10-15

    Research has demonstrated the toxic effects of methylmercury (MeHg), yet molecular mechanisms underlying its toxicity are not completely understood. Caenorhabditis elegans (C. elegans) offers a unique biological model to explore mechanisms of MeHg toxicity given many advantages associated with its ease of use and genetic power. Since our previous work indicated neurotoxic resistance of C. elegans to MeHg, the present study was designed to examine molecular mechanisms associated with this resistance. We hypothesized MeHg would induce expression of gst, hsp or mtl in vivo since glutathione (GSH), heat shock proteins (HSPs), and metallothioneins (MTs) have shown involvement in MeHg toxicity. Our studies demonstrated a modest, but significant increase in fluorescence in gst-4::GFP and mtl-1::GFP strains at an acute, low L1 MeHg exposure, whereas chronic L4 MeHg exposure induced expression of gst-4::GFP and hsp-4::GFP. Knockout gst-4 animals showed no alterations in lethality sensitivity compared to wildtype animals whereas mtl knockouts displayed increased sensitivity to MeHg exposure. GSH levels were increased by acute MeHg treatment and depleted with chronic exposure. We also demonstrate that MeHg induces hormesis, a phenotype whereby a sublethal exposure to MeHg rendered C. elegans resistant to subsequent exposure to the organometal. The involvement of gst-4, hsp-4, mtl-1, and mtl-2 in hormesis was examined. An increase in gst-4::GFP expression after a low-dose acute exposure to MeHg indicated that gst-4 may be involved in this response. Our results implicate GSH, HSPs, and MTs in protecting C. elegans from MeHg toxicity and show a potential role of gst-4 in MeHg-induced hormesis.

  1. Hormetic effect of methylmercury on Caenorhabditis elegans.

    PubMed

    Helmcke, Kirsten J; Aschner, Michael

    2010-10-15

    Research has demonstrated the toxic effects of methylmercury (MeHg), yet molecular mechanisms underlying its toxicity are not completely understood. Caenorhabditis elegans (C. elegans) offers a unique biological model to explore mechanisms of MeHg toxicity given many advantages associated with its ease of use and genetic power. Since our previous work indicated neurotoxic resistance of C. elegans to MeHg, the present study was designed to examine molecular mechanisms associated with this resistance. We hypothesized MeHg would induce expression of gst, hsp or mtl in vivo since glutathione (GSH), heat shock proteins (HSPs), and metallothioneins (MTs) have shown involvement in MeHg toxicity. Our studies demonstrated a modest, but significant increase in fluorescence in gst-4::GFP and mtl-1::GFP strains at an acute, low L1 MeHg exposure, whereas chronic L4 MeHg exposure induced expression of gst-4::GFP and hsp-4::GFP. Knockout gst-4 animals showed no alterations in lethality sensitivity compared to wildtype animals whereas mtl knockouts displayed increased sensitivity to MeHg exposure. GSH levels were increased by acute MeHg treatment and depleted with chronic exposure. We also demonstrate that MeHg induces hormesis, a phenotype whereby a sublethal exposure to MeHg rendered C. elegans resistant to subsequent exposure to the organometal. The involvement of gst-4, hsp-4, mtl-1, and mtl-2 in hormesis was examined. An increase in gst-4::GFP expression after a low-dose acute exposure to MeHg indicated that gst-4 may be involved in this response. Our results implicate GSH, HSPs, and MTs in protecting C. elegans from MeHg toxicity and show a potential role of gst-4 in MeHg-induced hormesis. PMID:20691719

  2. Eggshell thickness in mallards fed methylmercury

    SciTech Connect

    Heinz, G.H.

    1980-09-01

    Eggshell thinning has been linked to impaired reproduction in many wild birds. Previous work of my own and others led me to believe that methylmercury may cause some eggshell thinning in birds. The present study was designed to determine whether methylmercury in the diet of mallards would thin their eggshells and whether it would add to eggshell thinning caused by DDE.

  3. Iron status as a covariate in methylmercury-associated neurotoxicity risk.

    PubMed

    Fonseca, Márlon de Freitas; De Souza Hacon, Sandra; Grandjean, Philippe; Choi, Anna Lai; Bastos, Wanderley Rodrigues

    2014-04-01

    Intrauterine methylmercury exposure and prenatal iron deficiency negatively affect offspring's brain development. Since fish is a major source of both methylmercury and iron, occurrence of negative confounding may affect the interpretation of studies concerning cognition. We assessed relationships between methylmercury exposure and iron-status in childbearing females from a population naturally exposed to methylmercury through fish intake (Amazon). We concluded a census (refuse <20%) collecting samples from 274 healthy females (12-49 years) for hair-mercury determination and assessed iron-status through red cell tests and determination of serum ferritin and iron. Reactive C protein and thyroid hormones was used for excluding inflammation and severe thyroid dysfunctions that could affect results. We assessed the association between iron-status and hair-mercury by bivariate correlation analysis and also by different multivariate models: linear regression (to check trends); hierarchical agglomerative clustering method (groups of variables correlated with each other); and factor analysis (to examine redundancy or duplication from a set of correlated variables). Hair-mercury correlated weakly with mean corpuscular volume (r=.141; P=.020) and corpuscular hemoglobin (r=.132; .029), but not with the best biomarker of iron-status, ferritin (r=.037; P=.545). In the linear regression analysis, methylmercury exposure showed weak association with age-adjusted ferritin; age had a significant coefficient (Beta=.015; 95% CI: .003-.027; P=.016) but ferritin did not (Beta=.034; 95% CI: -.147 to .216; P=.711). In the hierarchical agglomerative clustering method, hair-mercury and iron-status showed the smallest similarities. Regarding factor analysis, iron-status and hair-mercury loaded different uncorrelated components. We concluded that iron-status and methylmercury exposure probably occur in an independent way. PMID:24411835

  4. Estimated intake levels for Finnish children of methylmercury from fish.

    PubMed

    Karjalainen, Anna K; Hallikainen, Anja; Hirvonen, Tero; Kiviranta, Hannu; Knip, Mikael; Kronberg-Kippilä, Carina; Leino, Olli; Simell, Olli; Sinkko, Harri; Tuomisto, Jouni T; Veijola, Riitta; Venäläinen, Eija-Riitta; Virtanen, Suvi M

    2013-04-01

    Methylmercury (MeHg) is a well-known neurotoxic agent, and consumption of contaminated fish is the principal environmental source of MeHg exposure in humans. Children are more susceptible to adverse effects than adults. No previous specific data exist for intake by Finnish children of methylmercury from fish. We estimated fish consumption and MeHg intakes from species most commonly consumed by Finnish children aged 1-6 years. The total mercury concentrations were determined in fish species consumed, and age-specific methylmercury intakes were derived. We also examined safety margins and the proportion of children exceeding the tolerable daily intakes set by international expert bodies. The daily intake of MeHg ranged from 0 to 0.33 μg/kg bw. The strictest reference value 0.1 μg/kg bw/day for MeHg, proposed by USEPA, was exceeded by 1-15% of the study population, and FAO/WHO JECFA provisional tolerable weekly intake of 1.6 μg/kg bw was exceeded by 1% of boys and 2.5% of girls aged 6 years. Intakes of 1-year old girls were higher than of boys, whereas for 3-year olds they were the opposite. The highest intakes were observed for 6-year-old boys and girls. There was great variation in the estimated MeHg intakes among Finnish children. PMID:22425939

  5. Protective effect of selenium on methylmercury toxicity: a possible mechanism

    SciTech Connect

    Chang, L.W.; Suber, R.

    1982-09-01

    Young adult male Charles River rats were injected (i.p.) with 2.0 mg/kg b.w. methylmercury chloride (MeHg), with 2.0 mg/kg b.w. sodium selenite (Se), or with 2.0 mg/kg b.w. MeHg and 2.0 mg/kg b.w. Se. Erythrocytic glutathione peroxidase activity was determined and the rate of oxidation of NADPH with t-butyl-hydroperoxide as a substrate was followed at 340 nm and 25/sup 0/C. Toxic signs (crossing reflex of the hind limbs) were displayed by MeHg-treated animals by the 6th week of intoxication. By 8 weeks of the experiment, overt neurological signs (crossing reflex, ataxic gait, and weight loss) were observed in MeHg-treated animals. No observable toxic signs or symptoms were evident in the control animals (saline or Se-treated) and in the MeHg/Se treated rats. Results have confirmed that exposure to methyl-mercury suppresses the activity of glutathione peroxidase. Furthermore, it was demonstrated that with co-administration of selenium (sodium selenite), the inhibitory effect of MeHg on GSH-Px was totally alleviated. These findings suggest that the level of GSH-Px level is important in influencing the toxic consequences in MeHg-intoxicated animals and may be useful as a predictive indicator for methylmercury toxic conditions of the animals. (JMT)

  6. Methylmercury in fish: a review of residue levels, fish consumption and regulatory action in the United States

    SciTech Connect

    Tollefson, L.; Cordle, F.

    1986-09-01

    The dangers associated with the consumption of large amounts of methylmercury in fish are well recognized, and there is some evidence to suggest that methylmercury may be the cause of subtle neurological impairments when ingested at even low to moderate levels, particularly the prenatal and early childhood periods. This concern has prompted a continuing assessment of the risk of methylmercury toxicity among fish consumers in the US as well as other countries. The toxicokinetics of methylmercury in humans are reviewed and used to estimate body burdens associated with toxic effects. To determine seafood consumption patterns among the continental US population the Food and Drug Administration (FDA) has analyzed data from a diary study commissioned by the Tuna Research Foundation. Mercury residue levels in domestic fish sampled by the FDA were used to determine the level of exposure to methylmercury. Until evidence is presented that substantially lowers the known body burden of methylmercury which causes toxicity, calculations indicate that the current 1.0 ppm regulatory level provides adequate protection for the average fish consumer, for young children, and for a significant number of consumers exceeding the acceptable daily intake. However, additional studies are being carried out in a continuing process to ensure that safe levels of prenatal exposure to mercury residues in fish are maintained.

  7. Methylmercury degradation by Pseudomonas putida V1.

    PubMed

    Cabral, Lucélia; Yu, Ri-Qing; Crane, Sharron; Giovanella, Patricia; Barkay, Tamar; Camargo, Flávio A O

    2016-08-01

    Environmental contamination of mercury (Hg) has caused public health concerns with focuses on the neurotoxic substance methylmercury, due to its bioaccumulation and biomagnification in food chains. The goals of the present study were to examine: (i) the transformation of methylmercury, thimerosal, phenylmercuric acetate and mercuric chloride by cultures of Pseudomonas putida V1, (ii) the presence of the genes merA and merB in P. putida V1, and (iii) the degradation pathways of methylmercury by P. putida V1. Strain V1 cultures readily degraded methylmercury, thimerosal, phenylmercury acetate, and reduced mercuric chloride into gaseous Hg(0). However, the Hg transformation in LB broth by P. putida V1 was influenced by the type of Hg compounds. The merA gene was detected in P. putida V1, on the other hand, the merB gene was not detected. The sequencing of this gene, showed high similarity (100%) to the mercuric reductase gene of other Pseudomonas spp. Furthermore, tests using radioactive (14)C-methylmercury indicated an uncommon release of (14)CO2 concomitant with the production of Hg(0). The results of the present work suggest that P. putida V1 has the potential to remove methylmercury from contaminated sites. More studies are warranted to determine the mechanism of removal of methylmercury by P. putida V1. PMID:27062344

  8. Effects of Injected Methylmercury on the Hatching of Common Loon (Gavia immer) Eggs

    EPA Science Inventory

    To determine the level of in ovo methylmercury (MeHg) exposure that results in detrimental effects on fitness and survival of loon embryos and hatched chicks, we conducted a field study in which we injected eggs with various doses of MeHg on day 4 of incubation. Eggs were collect...

  9. A review of methylmercury and child development.

    PubMed

    Myers, G J; Davidson, P W; Shamlaye, C F

    1998-04-01

    Methylmercury (MeHg) is a neurotoxin present in both fresh and saltwater fish throughout the world. Increased levels of MeHg can be found in individuals who regularly consume fish. The developing brain is very sensitive to the deleterious effects of MeHg, and prenatal exposure can occur when the mother has a diet high in fish. If the level of MeHg exposure achieved by eating fish adversely affects the fetus or child's neurological development it could have far reaching public health implications. Studies of human prenatal MeHg poisoning in Iraq suggest that MeHg levels achieved by eating fish may affect neurological development even when the fish MeHg levels are not elevated by obvious pollution. Studies in fish eating populations have identified adverse neurological and developmental outcomes, but these findings have not been consistent. Additional studies are presently underway to determine whether consistent adverse outcomes can be identified using more sensitive testing methods and examining children older than in previous studies. This review examines studies of human prenatal and postnatal MeHg exposure. Studies of poisoning episodes where children are symptomatic and studies of fish eating populations where no symptoms are apparent will be addressed. Individuals around the world depend on fish as a protein source and increasing evidence suggests that regular fish consumption has cardiovascular benefits. It is not presently clear whether MeHg exposures from a high fish diet adversely affect children's neurological development, but it is an important question to answer. PMID:9553968

  10. Immunofluorescence detection methods using microspheres

    NASA Astrophysics Data System (ADS)

    Szurdoki, Ferenc; Michael, Karri L.; Agrawal, Divya; Taylor, Laura C.; Schultz, Sandra L.; Walt, David R.

    1999-01-01

    Microsphere-based immunoassays were devised for compounds of agricultural and biomedical interest (e.g., digoxin, theophylline, and zearalenone). Commercially available microspheres with surface functional groups for chemical derivatization were used as solid carriers. After immobilizing the target substances, the surface of the haptenized microspheres was blocked by a protein to reduce aspecific binding. Competitive immunoassays were performed using the functionalized microspheres and antibodies labeled with horseradish peroxidase. Immunofluorescence signal amplification was achieved by enzyme-catalyzed reporter deposition (CARD). An epifluorescence microscope, a CCD camera interfaced with a computer, and microscopy image analysis software were employed for quantitative detection of fluorescent light emitted from individual microspheres. Integration of several such immunoassays and application of an optical encoding method enabled multianalyte determination. These immunoassays can also be utilized in an immunosensor array format. This immunoarray format could facilitate miniaturization and automation of multianalyte immunoassays.

  11. Assessing and Managing Methylmercury Risks Associated With Power Plant Mercury Emissions in the United States

    PubMed Central

    Charnley, Gail

    2006-01-01

    Abstract and Introduction Abstract Until the Clean Air Mercury Rule was signed in March 2005, coal-fired electric utilities were the only remaining, unregulated major source of industrial mercury emissions in the United States. Proponents of coal-burning power plants assert that methylmercury is not a hazard at the current environmental levels, that current technologies for limiting emissions are unreliable, and that reducing mercury emissions from power plants in the United States will have little impact on environmental levels. Opponents of coal-burning plants assert that current methylmercury exposures from fish are damaging to the developing nervous system of infants, children, and the fetus; that current technology can significantly limit emissions; and that reducing emissions will reduce exposure and risk. One concern is that local mercury emissions from power plants may contribute to higher local exposure levels, or “hot spots.” The impact of the Mercury Rule on potential hot spots is uncertain due to the highly site-specific nature of the relationship between plant emissions and local fish methylmercury levels. The impact on the primary source of exposure in the United States, ocean fish, is likely to be negligible due to the contribution of natural sources and industrial sources outside the United States. Another debate centers on the toxic potency of methylmercury, with the scientific basis of the US Environmental Protection Agency's (EPA's) recommended exposure limit questioned by some and defended by others. It is likely that the EPA's exposure limit may be appropriate for combined exposure to methylmercury and polychlorinated biphenyls (PCBs), but may be lower than the available data suggest is necessary to protect children from methylmercury alone. Mercury emissions from power plants are a global problem. Without a global approach to developing and implementing clean coal technologies, limiting US power plant emissions alone will have little

  12. Evolution of our understanding of methylmercury as a health threat.

    PubMed Central

    Watanabe, C; Satoh, H

    1996-01-01

    Methylmercury (MeHg) is recognized as one of the most hazardous environmental pollutants, primarily due to endemic disasters that have occurred repeatedly. A review of the earlier literature on the Minamata outbreak shows how large-scale poisoning occurred and why it could not be prevented. With the repeated occurrences of MeHg poisoning, it gradually became clear that the fetus is much more susceptible to the toxicity of this compound than the adult. Thus, recent epidemiologic studies in several fish-eating populations have focused on the effects of in utero exposure to MeHg. Also, there have been many studies on neurobehavioral effects of in utero exposure to methylmercury in rodents and nonhuman primates. The results of these studies revealed that the effects encompass a wide range of behavioral categories without clear identification of the functional categories distinctively susceptible to MeHg. The overall neurotoxicity of MeHg in humans, nonhuman primates, and rodents appears to have similarities. However, several gaps exist between the human and animal studies. By using the large body of neurotoxicologic data obtained in human populations and filling in such gaps, we can use MeHg as a model agent for developing a specific battery of tests of animal behavior to predict human risks resulting from in utero exposure to other chemicals with unknown neurotoxicity. Approaches developing such a battery are also discussed. PMID:9182044

  13. Hair methylmercury levels of mummies of the Aleutian Islands, Alaska

    SciTech Connect

    Egeland, G.M. Ponce, Rafael Bloom, Nicolas S. Knecht, Rick Loring, Stephen Middaugh, John P.

    2009-04-15

    Ancient human hair specimens can shed light on the extent of pre-historic exposures to methylmercury and provide valuable comparison data with current-day exposures, particularly for Indigenous Peoples who continue to rely upon local traditional food resources. Human hair from ancient Aleutian Island Native remains were tested for total and methylmercury (Hg, MeHg) and were radiocarbon dated. The remains were approximately 500 years old (1450 A.D.). For four adults, the mean and median total hair mercury concentration was 5.8 ppm (SD=0.9). In contrast, MeHg concentrations were lower with a mean of 1.2 ppm (SD=1.8) and a median of 0.54 ppm (0.12-3.86). For the five infants, the mean and median MeHg level was 1.2 ppm (SD=1.8) and 0.20 ppm (0.007-4.61), respectively. Segmental analyses showed variations in MeHg concentrations in 1-cm segments, consistent with fluctuations in naturally occurring exposure to mercury through dietary sources. The levels are comparable to or lower than those found in fish and marine mammal-eating populations today who rely far less on subsistence food than pre-historic humans. The findings are, therefore, compatible with increased anthropogenic release of trace metals during the past several centuries.

  14. Before You're Pregnant - Methylmercury

    MedlinePlus

    ... nutrients and it's low in fat. However, some fish contain high levels of methylmercury, which can harm ... a metal that can be found in certain fish, including swordfish , tilefish , king mackerel , and shark . Eating ...

  15. Methylmercury in hair fisherman for Turkish coasts

    SciTech Connect

    Vural, N.; Uenlue, H.

    1996-10-01

    Environmental methylmercury mainly arises from the methylation of inorganic mercury. The change in speciation of mercury from inorganic to methylated forms is the first step in the aquatic bioaccumulation processes. The bioconcentration factor of methylmercury in fish tissue to that in water is usually between 10{sup 4} and 10{sup 5}. Among seafood, fish products are the main source of methylmercury absorbed by men from the environment. Since Minimata epidemic health injuries and deaths in relation to mercury pollution, environmental and biological monitoring of inorganic and organic mercury species has gained importance through out the world and many reports have been published on the health effects and biological monitoring of mercury compounds including some Mediterranean countries. This study focuses on methylmercury in hair of fisherman living in different geographical Turkish coasts and relationship to eating fish habit. 17 refs., 1 fig., 2 tabs.

  16. Mercury and Methylmercury in Water and Bottom Sediments of Wetlands at Lostwood National Wildlife Refuge, North Dakota, 2003-04

    USGS Publications Warehouse

    Sando, Steven K.; Krabbenhoft, D.P.; Johnson, Kevin M.; Lundgren, Robert F.; Emerson, Douglas G.

    2007-01-01

    Certain ecosystem types, particularly wetlands, have environmental characteristics that can make them particularly sensitive to mercury inputs and that can result in large mercury concentrations in fish or other aquatic biota. To provide information needed to make effective management decisions to decrease human and wildlife exposure to methylmercury in northern prairie pothole wetlands, the U.S. Geological Survey, in cooperation with the North Dakota Department of Health, conducted a study to assess mercury and methylmercury concentrations in wetlands at the Lostwood National Wildlife Refuge (the Refuge) in northwest North Dakota. In April 2003 and 2004, water and bottom-sediment samples were collected from 44 individual wetlands that were classified as one of four wetland types. Many factors that may affect methylmercury production were considered in the study. The prairie pothole wetlands at the Refuge had large ranges in major environmental characteristics. Hydrologic differences, most notably semiannual wetting and drying cycles, that are intrinsic to prairie pothole wetlands affected methylmercury concentrations. This likely resulted from the stimulation of anaerobic microbial activity following reflooding of soils, particularly soils containing substantial organic carbon. Among the four wetland types considered for this study, seasonal and semipermanent wetlands generally had the largest methylmercury concentrations. Regardless of wetland type, however, methylmercury concentrations at the Refuge are large in relation to reported concentrations for natural aquatic systems.

  17. Functional MRI approach to developmental methylmercury and polychlorinated biphenyl neurotoxicity.

    PubMed

    White, Roberta F; Palumbo, Carole L; Yurgelun-Todd, Deborah A; Heaton, Kristin J; Weihe, Pal; Debes, Frodi; Grandjean, Philippe

    2011-12-01

    Prenatal and early childhood exposure to methylmercury (MeHg) or polychlorinated biphenyls (PCBs) are associated with deficits in cognitive, sensory, motor and other functions measured by neurobehavioral tests. The main objective of this pilot study was to determine whether functional magnetic resonance imaging (fMRI) is effective for visualization of brain function alterations related to neurobehavior in subjects with high prenatal exposure to the two neurotoxicants, MeHg and PCBs. Twelve adolescents (all boys) from a Faroese birth cohort assembled in 1986-1987 were recruited based on their prenatal exposures to MeHg and PCB. All underwent fMRI scanning during behavioral tasks at age 15 years. Subjects with high mixed exposure to MeHg and PCBs were compared to those with low mixed exposure on fMRI photic stimulation and a motor task. Boys with low mixed exposures showed patterns of fMRI activation during visual and motor tasks that are typical of normal control subjects. However, those with high exposures showed activation in more areas of the brain and different and wider patterns of activation than the low mixed exposure group. The brain activation patterns observed in association with increased exposures to MeHg and PCBs are meaningful in regard to the known neurotoxicity of these substances. This methodology therefore has potential utility in visualizing structural neural system determinants of exposure-induced neurobehavioral dysfunction. PMID:21545807

  18. Functional MRI approach to developmental methylmercury and polychlorinated biphenyl neurotoxicity

    PubMed Central

    White, Roberta F.; Palumbo, Carole L.; Yurgelun-Todd, Deborah A.; Heaton, Kristin J.; Weihe, Pal; Debes, Frodi; Grandjean, Philippe

    2015-01-01

    Prenatal and early childhood exposure to methylmercury (MeHg) or polychlorinated biphenyls (PCBs) are associated with deficits in cognitive, sensory, motor and other functions measured by neurobehavioral tests. The main objective of this pilot study was to determine whether functional magnetic resonance imaging (fMRI) is effective for visualization of brain function alterations related to neurobehavior in subjects with high prenatal exposure to the two neurotoxicants, MeHg and PCBs. Twelve adolescents (all boys) from a Faroese birth cohort assembled in 1986–1987 were recruited based on their prenatal exposures to MeHg and PCB. All underwent fMRI scanning during behavioral tasks at age 15 years. Subjects with high mixed exposure to MeHg and PCBs were compared to those with low mixed exposure on fMRI photic stimulation and a motor task. Boys with low mixed exposures showed patterns of fMRI activation during visual and motor tasks that are typical of normal control subjects. However, those with high exposures showed activation in more areas of the brain and different and wider patterns of activation than the low mixed exposure group. The brain activation patterns observed in association with increased exposures to MeHg and PCBs are meaningful in regard to the known neurotoxicity of these substances. This methodology therefore has potential utility in visualizing structural neural system determinants of exposure-induced neurobehavioral dysfunction. PMID:21545807

  19. Immunofluorescent Staining of Mouse Intestinal Stem Cells

    PubMed Central

    O’Rourke, Kevin P.; Dow, Lukas E; Lowe, Scott W

    2016-01-01

    Immunofluorescent staining of organoids can be performed to visualize molecular markers of cell behavior. For example, cell proliferation marked by incorporation of nucleotide (EdU), or to observe markers of intestinal differentiation including paneth cells, goblet cells, or enterocytes (see Figure 1). In this protocol we detail a method to fix, permeabilize, stain and mount intestinal organoids for analysis by immunofluorescent confocal microscopy.

  20. Methylmercury disrupts the balance between phosphorylated and non-phosphorylated cofilin in primary cultures of mice cerebellar granule cells A proteomic study

    SciTech Connect

    Vendrell, Iolanda; Carrascal, Montserrat; Abian, Joaquin

    2010-01-01

    Methylmercury is an environmental contaminant that is particularly toxic to the developing central nervous system; cerebellar granule neurons are especially vulnerable. Here, primary cultures of cerebellar granule cells (CGCs) were continuously exposed to methylmercury for up to 16 days in vitro (div). LC50 values were 508 +- 199, 345 +- 47, and 243 +- 45 nM after exposure for 6, 11, and 16 div, respectively. Proteins from cultured mouse CGCs were separated by 2DE. Seventy-one protein spots were identified by MALDI-TOF PMF and MALDI-TOF/TOF sequencing. Prolonged exposure to a subcytotoxic concentration of methylmercury significantly increased non-phosphorylated cofilin both in cell protein extracts (1.4-fold; p < 0.01) and in mitochondrial-enriched fractions (1.7-fold; p < 0.01). The decrease in P-cofilin induced by methylmercury was concentration-dependent and occurred after different exposure times. The percentage of P-cofilin relative to total cofilin significantly decreased to 49 +- 13% vs. control cells after exposure to 300 nM methylmercury for 5 div. The balance between the phosphorylated and non-phosphorylated form of cofilin regulates actin dynamics and facilitates actin filament turnover. Filamentous actin dynamics and reorganization are responsible of neuron shape change, migration, polarity formation, regulation of synaptic structures and function, and cell apoptosis. An alteration of the complex regulation of the cofilin phosphorylation/dephosphorylation pathway could be envisaged as an underlying mechanism compatible with reported signs of methylmercury-induced neurotoxicity.

  1. [Methylmercury: existing recommendations; methods of analysing and interpreting the results; economic evaluation].

    PubMed

    González-Estecha, Montserrat; Bodas-Pinedo, Andrés; Martínez-García, María José; Trasobares-Iglesias, Elena M; Bermejo-Barrera, Pilar; Ordóñez-Iriarte, José María; Llorente-Ballesteros, María Teresa; Prieto-Menchero, Santiago; Guillén-Pérez, José Jesús; Martell-Claros, Nieves; Cuadrado-Cenzual, María Ángeles; Rubio-Herrera, Miguel Ángel; Martínez-Álvarez, Jesús Román; Calvo-Manuel, Elpidio; Farré-Rovira, Rosaura; Herráiz-Martínez, Miguel Ángel; Bretón Lesmes, Irene; García-Donaire, José Antonio; Sáinz-Martín, María; Martínez-Astorquiza, Txantón; Gallardo-Pino, Carmen; Moreno-Rojas, Rafael; Salas-Salvadó, Jordi; Blanco Fuentes, María; Arroyo-Fernández, Manuel; Calle Pascual, Alfonso

    2015-01-01

    The beneficial effects of fish consumption are well- known. Nevertheless, there is worldwide concern regard methylmercury concentrations in fish, which is why many countries such as the United States, Australia, New Zealand, Canada and numerous European countries have made fish consumption recommendations for their populations, particularly vulnerable groups, in order to México methylmercury intake. Blood and hair are the best biological samples for measuring methylmercury. The most widely-used method to analyse methylmercury is cold vapor atomic absorption spectrometry, although there are also direct methods based on the thermal decomposition of the sample. In recent years, the number of laboratories that measure mercury by inductively coupled plasma mass spectrometry has increased. In addition, the different kinds of mercury can be distinguished by coupling chromatography methods of separation. Laboratories that analyse mercury in biological samples need to participate in external quality control programmes. Even if mercury emissions are reduced, mercury may remain in the environment for many years, so dietary recommendations are fundamental in order to reduce exposure. It is necessary to propose public health measures aimed at decreasing mercury exposure and to evaluate the benefits of such measures from the economic and social standpoints. PMID:25561094

  2. DOE/FDA/EPA: Workshop on methylmercury and human health

    SciTech Connect

    Moskowitz, P.D.; Saroff, L.; Bolger, M.; Cicmanec, J.; Durkee, S.

    1994-12-31

    In the US the general population is exposed to methylmercury (MeHg) principally through the consumption of fish. There is continuing discussion about the sources of this form of mercury (Hg), the magnitudes and trends in exposures to consumers, and the significance of the sources and their contributions to human health. In response to these discussions, the US Department of Energy, the US Food and Drug Administration, and the US Environmental Protection Agency cosponsored a two-day workshop to discuss data and methods available for characterizing the risk to human health presented by MeHg. This workshop was attended by 45 individuals representing various Federal and state organizations and interested stakeholders. The agenda covered: Agency interests; probabilistic approach to risk assessment; emission sources; atmospheric transport; biogeochemical cycling; exposure assessment; health effects of MeHg; and research needs.

  3. Oxidative stress in songbirds exposed to dietary methylmercury.

    PubMed

    Henry, Katie A; Cristol, Daniel A; Varian-Ramos, Claire W; Bradley, Eric L

    2015-04-01

    Long-term, sublethal methylmercury exposure can cause reproductive depression, immune suppression, endocrine disruption and other problems in birds. We used two biomarkers to detect oxidative stress in livers of zebra finches (Taeniopygia guttata) developmentally exposed to sublethal levels of dietary methylmercury (0.0, 0.3, 0.6, 1.2, or 2.4 μg/g wet weight in diet). Our findings indicate that young adult finches exposed to environmentally relevant concentrations of mercury in ovo and through their diets, exhibited oxidative stress in their livers. We measured the ratio of the antioxidant glutathione in its reduced form (GSH) versus its oxidized form (GSSG) and the activity of the superoxide dismutase (SOD) enzyme suite. Blood total mercury served as a proxy for liver mercury concentration, and was on average 8.4 times the dietary dose (e.g., birds consuming 0.6 μg/g had blood mercury levels of ~5 μg/g on a wet weight basis). Consistent with what is known from large, aquatic bird species, there was a significant, negative relationship between GSH/GSSG ratios and tissue mercury concentrations, which is indicative of oxidative stress. This relationship was driven by a significant increase in the oxidized glutathione in the livers of birds with higher blood mercury levels. SOD activity was also found to have a significant, negative relationship with blood mercury. PMID:25519780

  4. Embryotoxicity of maternally transferred methylmercury to fathead minnows (Pimephales promelas).

    PubMed

    Bridges, Kristin N; Soulen, Brianne K; Overturf, Carmen L; Drevnick, Paul E; Roberts, Aaron P

    2016-06-01

    Mercury (Hg) is a ubiquitous environmental contaminant and potent neurotoxin. In aquatic environments, Hg can be transformed into methylmercury (MeHg), which bioaccumulates in aquatic food webs, including fish. Methylmercury has been shown to transfer from female fish to developing eggs; however, relatively little is known regarding the effects of maternally transferred MeHg on fish embryos. The present study evaluated the effects of maternally transferred MeHg on fathead minnow (Pimephales promelas) embryos. Embryos were collected from adult fatheads exposed for 30 d to 1 of 3 diets spiked with MeHg: a control diet (0.02 ppm Hg dry wt), a low diet (0.87 ppm Hg dry wt), or a high diet (5.5 ppm Hg dry wt). No effects on spawning frequency, clutch size, or total egg output were observed. In embryos, Hg concentration was a function of female diet and the duration (number of days) of female exposure. Compared with controls, embryos from the low-diet treatment displayed altered embryonic movement patterns (hyperactivity) and decreased time to hatch. Embryos from the high-diet treatment had delayed hatching and increased mortality compared with the other treatments. Collectively, these results suggest that maternally transferred Hg may impact survival, behavior, and developmental milestones of the embryo-larval stages of fish. Environ Toxicol Chem 2016;35:1436-1441. © 2015 SETAC. PMID:26471903

  5. Cryosectioning of undecalcified tissues for immunofluorescence.

    PubMed

    Rijntjes, N V; Van de Putte, L B; Van der Pol, M; Guelen, P J

    1979-01-01

    The present report describes a procedure for preparing 4--6 micrometers cryostat sections of undecalcified fresh frozen tissue which contain hard tissue, for immunofluorescence. The apparatus used is a cryomicrotome originally designed for cutting sections for whole body autoradiography. To obtain cryostat sections suitable for tissue immunofluorescence the standard procedure was modified with respect to the hardness and edges of the microtome knife, the temperature of the cryostat and the carboxymethyl cellulose concentration of the embedding material. PMID:387879

  6. EFFECTS OF METHYLMERCURY ON REPRODUCTION IN AMERICAN KESTRELS AND COMPARISON TO EFFECTS OBSERVED IN OTHER AVIAN SPECIES

    EPA Science Inventory

    A study of the effects of methylmercury on reproduction in American kestrels was conducted in conjunction with the USGS Patuxent Wildlife Research Center as part of a larger project to improve our understanding of the effects of mercury exposure in the environment to avian popula...

  7. REFERENCE DOSE FOR METHYLMERCURY (EXTERNAL REVIEW DRAFT)

    EPA Science Inventory

    In 1997, U.S. EPA issued the Mercury Study Report to Congress (MSRC). Among the assessments in the MSRC was a state-of-the-science evaluation of the health effects of methylmercury. There has been considerable discussion within the scientific community regarding the level of e...

  8. Neurotoxicity of lead, methylmercury, and PCBs in relation to the Great Lakes.

    PubMed Central

    Rice, D C

    1995-01-01

    There is ample evidence identifying lead, methylmercury, and polychlorinated biphenyls (PCBs) as neurotoxic agents. A large body of data on the neurotoxicity of lead, based on both epidemiologic studies in children and animal models of developmental exposure, reveals that body burdens of lead typical of people in industrialized environments produce behavioral impairment. Methylmercury was identified as a neurotoxicant in both adults and the developing organism based on episodes of human poisoning: these effects have been replicated and extended in animals. High-dose PCB exposure was recognized as a developmental toxicant as a result of several episodes of contamination of cooking oil. The threshold for PCB neurotoxicity in humans is less clear, although research in animals suggests that relatively low-level exposure produces behavioral impairment and other toxic effects. Tissue levels in fish below which human health would not be adversely affected were estimated for methylmercury and PCBs based on calculated reference doses (RfDs) and estimated fish intake. Present levels in fish tissue in the Great Lakes exceed these levels for both neurotoxicants. Great Lakes fish and water do not pose a particular hazard for increased lead intake. However, the fact that the present human body burden is in a range at which functional deficits are probable suggests that efforts should be made to eliminate point sources of lead contamination in the Great Lakes basin. PMID:8635443

  9. Transport of pyruvate into mitochondria is involved in methylmercury toxicity

    PubMed Central

    Lee, Jin-Yong; Ishida, Yosuke; Takahashi, Tsutomu; Naganuma, Akira; Hwang, Gi-Wook

    2016-01-01

    We have previously demonstrated that the overexpression of enzymes involved in the production of pyruvate, enolase 2 (Eno2) and D-lactate dehydrogenase (Dld3) renders yeast highly sensitive to methylmercury and that the promotion of intracellular pyruvate synthesis may be involved in intensifying the toxicity of methylmercury. In the present study, we showed that the addition of pyruvate to culture media in non-toxic concentrations significantly enhanced the sensitivity of yeast and human neuroblastoma cells to methylmercury. The results also suggested that methylmercury promoted the transport of pyruvate into mitochondria and that the increased pyruvate concentrations in mitochondria were involved in intensifying the toxicity of methylmercury without pyruvate being converted to acetyl-CoA. Furthermore, in human neuroblastoma cells, methylmercury treatment alone decreased the mitochondrial membrane potential, and the addition of pyruvate led to a further significant decrease. In addition, treatment with N-acetylcysteine (an antioxidant) significantly alleviated the toxicity of methylmercury and significantly inhibited the intensification of methylmercury toxicity by pyruvate. Based on these data, we hypothesize that methylmercury exerts its toxicity by raising the level of pyruvate in mitochondria and that mitochondrial dysfunction and increased levels of reactive oxygen species are involved in the action of pyruvate. PMID:26899208

  10. Epidemiological studies of neurological signs and symptoms and blood pressure in populations near the industrial methylmercury contamination at Minamata, Japan.

    PubMed

    Yorifuji, Takashi; Tsuda, Toshihide

    2016-07-01

    Severe methylmercury exposure occurred in Minamata, Japan. Only a limited number of epidemiological studies related to that exposure have been carried out. The evidence that methylmercury is cardiotoxic is very limited, and these studies provide only minimal support for that hypothesis. We therefore analyzed the data both from an investigation in Minamata and neighboring communities in 1971 and an investigation in 1974 in another area simultaneously. We included a total of 3,751 participants. We examined the association of residential area with neurological signs or blood pressure using logistic regression or multiple linear regression models, adjusting for sex and age. We found that the prevalence of neurological signs and symptoms was elevated in the Minamata area (high-exposure), followed by the Goshonoura area (medium-exposure). Moreover, blood pressure was elevated in residents of the Minamata area. PMID:26299421

  11. Immunofluorescence Staining — EDRN Public Portal

    Cancer.gov

    Direct immunofluorescence method is used to detect the deposit of immunoglobulins, complement components, fibrinogen, etc. in tissues. This technique is usually performed on frozen sections. The primary antibody is conjugated to fluorescein binds directly with the antigen and can be detected by the fluorescent tag using a fluorescent microscope.

  12. Dietary toxicity and tissue accumulation of methylmercury in American kestrels

    USGS Publications Warehouse

    Bennett, R.S.; French, J.B., Jr.; Rossmann, R.; Haebler, R.

    2009-01-01

    American kestrels (Falco sparverius) were fed meat diets containing 0, 3, 6, or 12 ppm (dry weight) methylmercury chloride. Birds fed the 12-ppm diet started to show signs of neurotoxicity after 26 days and all died in 39?49 days. One male kestrel fed the 6-ppm diet died after 75 days of exposure and several others showed signs of neurotoxicity after 45 days. None of the birds fed the 3-ppm diet died or showed signs of toxicity. After 59 days of exposure, mercury concentrations in the liver, kidney, and blood of nonreproducing kestrels increased with increasing dietary concentration. Tissue concentrations of mercury also steadily increased over time in birds fed diets with 6 ppm mercury, which were necropsied at 8, 15, 29, or 59 days of exposure, reaching mean total mercury concentrations of 57, 46, and 45 ppm (wet weight) at 59 days in the liver, kidney, and whole blood, respectively. Two pairs of kestrels at each dietary concentration were allowed to breed. Eggs averaged 8.3 and 18.1 ppm (wet weight) total mercury from birds fed 3- and 6-ppm diets, respectively. Feathers grown during mercury exposure contained high concentrations of mercury: Birds fed 3- and 6-ppm diets contained 275 and 542 ppm total mercury, respectively.

  13. Effect of methylmercury on acetylcholinestrase and serum cholinesterase activity in monkeys, Macaca fascicularis

    SciTech Connect

    Petruccioli, L.; Turillazzi, P.G. )

    1991-05-01

    The consumption of fish and fish-derived products is the main pathway of human exposure to methylmercury (MeHg). Methylmercury levels vary widely in fish, depending on age, size, the position of the species in the food chain, and most of all, on pollution levels. MeHg affects the Acetylcholinesterase activity (AChE) and the serum Cholinesterase activity (BChE). Histoenzymatic studies showed that 100mg Methyoxyethylmercury chloride administered for 6 days to rats caused a reduction of AChE activity in the thalamus and an increase in different parts of the nervous central system. The present study aims at verifying whether the dose permitted by F.A.O. and doses 10 and 100 fold higher affect the Cholinesterase activity in primates, and whether there is a correlation between AChE and BChE.

  14. Vitamins and monothiols efficacy in the restoration of adenosine nucleotide degradation enzymes altered during methylmercury intoxication

    SciTech Connect

    Sood, P.P.; Bapu, C.; Vijayalakshmi, K.

    1995-12-31

    Male albino mice were intoxicated with a daily dose of 1 mg/kg of methylmercury chloride (MMC) for 7 days, and were treated thereafter with glutathione, N-acetyl-DL-homocysteine thiolactone, vitamin B complex, and vitamin E, either alone or in combinations for the next 7 days. The animals were sacrificed on the eighth day, with the exception of one group that was kept without toxic exposure for an additional 7 days and sacrificed on the fifteenth day. Brain, spinal cord, kidney, and liver of the animals were examined for changes in adenosine deaminase and 5{prime} nucleotidase. We found a severe inhibition of these enzymes during MMC intoxication and significant recovery during monothiols and vitamins administration, indicating the effectiveness of these agents in methylmercury detoxication. 26 refs., 2 figs.

  15. Methylmercury-mediated inhibition of 3H-D-aspartate transport in cultured astrocytes is reversed by the antioxidant catalase.

    PubMed

    Allen, J W; Mutkus, L A; Aschner, M

    2001-05-25

    Astrocytes are essential for removal of glutamate from the extracellular space in the central nervous system. The neurotoxic heavy metal methylmercury potently and specifically inhibits the transport of glutamate in cultured astrocytes by an unknown mechanism. Glutamate transport in astrocytes is also inhibited by reactive oxygen species. A glutamate-induced transporter current is inhibited both by reactive oxygen species and thiol oxidizing agents. These observations suggest that oxidation of the transporter might mediate methylmercury-induced inhibition of glutamate transport. In the present study, we examined the ability of thiol reducing or oxidizing agents to inhibit transport of 3H-D-aspartate, a glutamate analog, in primary cultures of neonatal rat astrocytes. To assess if methylmercury-mediated inhibition of 3H-aspartate transport was due to overproduction of reactive oxygen species, we tested the ability of Trolox, alpha-phenyl-tert-butyl nitrone (PBN), or catalase to attenuate the methylmercury-induced inhibition of aspartate uptake. Neither the thiol reducing agent dithiothreitol (DTT), nor the thiol oxidizing agent 5,5'-dithio-bis(2-nitrobenzoic) acid (DTNB) had any effect on 3H-aspartate transport suggesting that the thiol redox state does not alter transporter function. In contrast, the antioxidant catalase (1000 U/ml) significantly attenuated methylmercury-induced inhibition of 3H-aspartate uptake, suggesting that excess reactive oxygen species, specifically H2O2, inhibit the function of an astrocytic excitatory amino acid transporter (EAAT1). Prolonged exposure (6 h) to inhibitors of glutamate transport significantly decreased EAAT1 mRNA levels suggesting that transporter expression is related to function. This study suggests that methylmercury-induced overproduction of H2O2 is a mechanism for inhibition of glutamate transport and transporter expression in cultured astrocytes. PMID:11376598

  16. FISH CONSUMPTION, METHYLMERCURY, AND HUMAN HEART DISEASE.

    SciTech Connect

    LIPFERT, F.W.; SULLIVAN, T.M.

    2005-09-21

    Environmental mercury continues to be of concern to public health advocates, both in the U.S. and abroad, and new research continues to be published. A recent analysis of potential health benefits of reduced mercury emissions has opened a new area of public health concern: adverse effects on the cardiovascular system, which could account for the bulk of the potential economic benefits. The authors were careful to include caveats about the uncertainties of such impacts, but they cited only a fraction of the applicable health effects literature. That literature includes studies of the potentially harmful ingredient (methylmercury, MeHg) in fish, as well as of a beneficial ingredient, omega-3 fatty acids or ''fish oils''. The U.S. Food and Drug Administration (FDA) recently certified that some of these fat compounds that are primarily found in fish ''may be beneficial in reducing coronary heart disease''. This paper briefly summarizes and categorizes the extensive literature on both adverse and beneficial links between fish consumption and cardiovascular health, which are typically based on studies of selected groups of individuals (cohorts). Such studies tend to comprise the ''gold standard'' of epidemiology, but cohorts tend to exhibit a great deal of variability, in part because of the limited numbers of individuals involved and in part because of interactions with other dietary and lifestyle considerations. Note that eating fish will involve exposure to both the beneficial effects of fatty acids and the potentially harmful effects of contaminants like Hg or PCBs, all of which depend on the type of fish but tend to be correlated within a population. As a group, the cohort studies show that eating fish tends to reduce mortality, especially due to heart disease, for consumption rates up to about twice weekly, above which the benefits tend to level off. A Finnish cohort study showed increased mortality risks in the highest fish-consuming group ({approx}3 times

  17. Immunofluorescence profile of discoid lupus erythematosus.

    PubMed

    Bharti, Shreekant; Dogra, Sunil; Saikia, Biman; Walker, Ranjana Minz; Chhabra, Seema; Saikia, Uma Nahar

    2015-01-01

    The direct immunofluorescence (DIF) of skin in conjunction with histopathology gives the best diagnostic yield. It is invaluable in confirming the diagnosis of small vessel vasculitides and bullous lesions of the skin and can be used as an additional tool to pinpoint the diagnosis of systemic and localized autoimmune diseases involving the skin. This study was undertaken to analyze the strength of DIF vis-à -vis histopathology in the diagnosis of discoid lupus erythematosus (DLE) and at the same time to elaborate the specific immunofluorescence findings in the lesions of DLE. The clinical profile and cutaneous lesions of 75 patients with DLE are described. DIF was positive in 68% and histopathology in 60% of cases. The most common immunoreactant was IgG at the dermoepidermal junction, followed by IgM and IgA. A conclusive diagnosis of DLE could be achieved satisfactorily in 64 cases (85%) by a combination of the two techniques. PMID:26549071

  18. N-acetylcysteine as an antidote in methylmercury poisoning.

    PubMed Central

    Ballatori, N; Lieberman, M W; Wang, W

    1998-01-01

    Methylmercury is a ubiquitous environmental pollutant and potent neurotoxin. Treatment of methylmercury poisoning relies almost exclusively on the use of chelating agents to accelerate excretion of the metal. The present study demonstrates that oral administration of N-acetylcysteine (NAC), a widely available and largely nontoxic amino acid derivative, produces a profound acceleration of urinary methylmercury excretion in mice. Mice that received NAC in the drinking water (10 mg/ml) starting at 48 hr after methylmercury administration excreted from 47 to 54% of the 203Hg in urine over the subsequent 48 hr, as compared to 4-10% excretion in control animals. When NAC-containing water was given from the time of methylmercury administration, it was even more effective at enhancing urinary methylmercury excretion and at lowering tissue mercury levels. In contrast, excretion of inorganic mercury was not affected by oral NAC administration. The ability of NAC to enhance methylmercury excretion when given orally, its relatively low toxicity, and is wide availability in the clinical setting indicate that it may be an ideal therapeutic agent for use in methylmercury poisoning. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:9520359

  19. Possible physiological uptake mechanism of methylmercury by the marine bloodworm (Glycera dibranchiata)

    SciTech Connect

    Medeiros, D.M.; Cadwell, L.L.; Preston, R.L.

    1980-01-01

    The uptake of methylmercury by fish has been studied extensively. There have been some studies on marine invertebrates. These studies have been concerned with either the effect of methylmercury on viability or methylmercury distribution among body parts. The physiological uptake mechanisms of methylmercury in aquatic organisms have not been studied. The objective of this paper is to examine the uptake mechanism of methylmercury from water in a lower-food-chain organism, the marine bloodworm (Glycera dibranchi-ata).

  20. Characterization of the effects of methylmercury on Caenorhabditis elegans

    SciTech Connect

    Helmcke, Kirsten J.; Syversen, Tore; Miller, David M.; Aschner, Michael

    2009-10-15

    The rising prevalence of methylmercury (MeHg) in seafood and in the global environment provides an impetus for delineating the mechanism of the toxicity of MeHg. Deleterious effects of MeHg have been widely observed in humans and in other mammals, the most striking of which occur in the nervous system. Here we test the model organism, Caenorhabditis elegans (C. elegans), for MeHg toxicity. The simple, well-defined anatomy of the C. elegans nervous system and its ready visualization with green fluorescent protein (GFP) markers facilitated our study of the effects of methylmercuric chloride (MeHgCl) on neural development. Although MeHgCl was lethal to C. elegans, induced a developmental delay, and decreased pharyngeal pumping, other traits including lifespan, brood size, swimming rate, and nervous system morphology were not obviously perturbed in animals that survived MeHgCl exposure. Despite the limited effects of MeHgCl on C. elegans development and behavior, intracellular mercury (Hg) concentrations ({<=} 3 ng Hg/mg protein) in MeHgCl-treated nematodes approached levels that are highly toxic to mammals. If MeHgCl reaches these concentrations throughout the animal, this finding indicates that C. elegans cells, particularly neurons, may be less sensitive to MeHgCl toxicity than mammalian cells. We propose, therefore, that C. elegans should be a useful model for discovering intrinsic mechanisms that confer resistance to MeHgCl exposure.

  1. Characterization of the effects of methylmercury on Caenorhabditis elegans

    PubMed Central

    Helmcke, Kirsten J.; Syversen, Tore; Miller, David M.; Aschner, Michael

    2009-01-01

    The rising prevalence of methylmercury (MeHg) in seafood and in the global environment provides an impetus for delineating the mechanism of the toxicity of MeHg. Deleterious effects of MeHg have been widely observed in humans and in other mammals, the most striking of which occur in the nervous system. Here we test the model organism, Caenorhabditis elegans (C. elegans), for MeHg toxicity. The simple, well-defined anatomy of the C. elegans nervous system and its ready visualization with green fluorescent protein (GFP) markers facilitated our study of the effects of methylmercuric chloride (MeHgCl) on neural development. Although MeHgCl was lethal to C. elegans, induced a developmental delay, and decreased pharyngeal pumping, other traits including lifespan, brood size, swimming rate, and nervous system morphology were not obviously perturbed in animals that survived MeHgCl exposure. Despite the limited effects of MeHgCl on C. elegans development and behavior, intracellular mercury (Hg) concentrations (≤ 3 ng Hg/mg protein) in MeHgCl-treated nematodes approached levels that are highly toxic to mammals. If MeHgCl reaches these concentrations throughout the animal, this finding indicates that C. elegans cells, particularly neurons, may be less sensitive to MeHgCl toxicity than mammalian cells. We propose, therefore, that C. elegans should be a useful model for discovering intrinsic mechanisms that confer resistance to MeHgCl exposure. PMID:19341752

  2. Methylmercury monitoring study in Karakuwacho peninsula area in Japan.

    PubMed

    Yan, Junxia; Inoue, Kayoko; Asakawa, Akihiro; Harada, Kouji H; Watanabe, Takao; Hachiya, Noriyuki; Koizumi, Akio

    2014-07-01

    Methylmercury (MeHg) is a worldwide concern owing to its adverse health effects. To explore MeHg exposure burdens and the potential contributing factors in different subpopulations in a peninsula area (Karakuwacho) in Japan, a cross-sectional survey was performed. This study included 189 individuals from 102 families. The geometric means of total hair mercury (THg) were 5.74, 3.78 and 2.37 μg/g for adult males, females and children, respectively, of which 56.5 %, 30.9 % and 12.9 % had hair THg exceeding 5 μg/g, respectively. Tuna and mackerel were the common fish species that were positively correlated with hair THg levels in different subpopulations (standardized coefficient ranged from 0.20 to 0.58, p < 0.05). Frequent consumption of these fish species and a large amount of fish intake are likely major contributors of MeHg exposure in this area. Local-scale risk evaluation and risk communication should be highlighted in future studies. PMID:24599146

  3. Role of direct immunofluorescence in dermatological disorders

    PubMed Central

    Mysorekar, Vijaya V.; Sumathy, T. K.; Shyam Prasad, A. L.

    2015-01-01

    Background: Direct immunofluorescence (DIF) test for tissue-bound autoantibodies, has been found to be of value in the diagnosis of several dermatological disorders. The location and pattern of deposition of immunoreactants helps in classifying various immune-mediated diseases. Aims and Objectives: The aim of this study was to analyze the concordance between the clinical, histopathological and DIF diagnosis in bullous and nonbullous lesions of the skin, and thus determine the impact of immunofluorescence on diagnosis. Materials and Methods: A total of 215 skin biopsies performed in suspected immune-mediated vesiculobullous disease, vasculitis or dermatosis, were studied. Histopathological examination was done along with DIF study for deposits of immunoglobulin G(IgG), IgA, IgM, and C3. Results: Direct immunofluorescence was positive in 103/215 cases. There was very good concordance between the clinical, histological and DIF results (observed agreement = 93.4%, κ =0.90, with 95% confidence interval = 0.86–0.94). The overall sensitivity of DIF in immune-mediated skin disorders was 98.0%. DIF was positive in 52/53 cases (98.1%) in the pemphigus group and 24/25 (96.0%) bullous pemphigoid cases. None of the clinically suspected cases of dermatitis herpetiformis showed DIF positivity. A positive lupus band test was seen in 9/9 (100%) cases of lupus erythematosus. DIF was positive in 10/10 (100%) clinically suspected cases of Henoch–Schönlein purpura. In 110 cases, negative DIF results helped to rule out immune-mediated vesiculobullous disorders, lupus erythematosus and vasculitis, and the final diagnosis was made on the basis of the clinical features and/or histopathology. Conclusion: Direct immunofluorescence is a useful supplement for the accurate diagnosis of immune-mediated dermatological disorders, and helps to classify various autoimmune bullous disorders. When the clinical features/histopathology are inconclusive, the diagnosis often can be made on the basis

  4. THE USE OF LOCAL MERCURY DEPOSITION MEASUREMENTS IN MODELING THE FATE, TRANSPORT AND BIOACCUMULATION OF METHYLMERCURY ON THE CHEYENNE RIVER SIOUX TRIBAL LANDS

    EPA Science Inventory

    Managed farm ponds on Sioux Tribal lands were monitored as a part of a two year study to address the variation in methylmercury bioaccumulation in fishes from 2003-2004. Initial tissue residue monitoring suggested that larger ponds posed less risk for human exposure to methylmer...

  5. SUB-ACUTE TREATMENT WITH METHYLMERCURY DURING DIFFERENTIATION OF PHEOCHROMOCYTOMA (PC12) CELLS DOES NOT ALTER BINDING OF ION CHANNEL LIGANDS OR CELL MORPHOLOGY.

    EPA Science Inventory

    We demonstrated recently that 6 days of exposure to nanomolar concentrations (3-10 nM) of methylmercury (MeHg) during nerve growth factor (NGF) induced PC12 cell differentiation reduced the amplitude and density of voltage-gated sodium and calcium currents. In the present study,...

  6. Comparative toxicogenomic responses of mercuric and methyl-mercury

    PubMed Central

    2013-01-01

    Background Mercury is a ubiquitous environmental toxicant that exists in multiple chemical forms. A paucity of information exists regarding the differences or similarities by which different mercurials act at the molecular level. Results Transcriptomes of mixed-stage C. elegans following equitoxic sub-, low- and high-toxicity exposures to inorganic mercuric chloride (HgCl2) and organic methylmercury chloride (MeHgCl) were analyzed. In C. elegans, the mercurials had highly different effects on transcription, with MeHgCl affecting the expression of significantly more genes than HgCl2. Bioinformatics analysis indicated that inorganic and organic mercurials affected different biological processes. RNAi identified 18 genes that were important in C. elegans response to mercurial exposure, although only two of these genes responded to both mercurials. To determine if the responses observed in C. elegans were evolutionarily conserved, the two mercurials were investigated in human neuroblastoma (SK-N-SH), hepatocellular carcinoma (HepG2) and embryonic kidney (HEK293) cells. The human homologs of the affected C. elegans genes were then used to test the effects on gene expression and cell viability after using siRNA during HgCl2 and MeHgCl exposure. As was observed with C. elegans, exposure to the HgCl2 and MeHgCl had different effects on gene expression, and different genes were important in the cellular response to the two mercurials. Conclusions These results suggest that, contrary to previous reports, inorganic and organic mercurials have different mechanisms of toxicity. The two mercurials induced disparate effects on gene expression, and different genes were important in protecting the organism from mercurial toxicity. PMID:24118919

  7. Comparison of mercury accumulation among the brain, liver, kidney, and the brain regions of rats administered methylmercury in various phases of postnatal development

    SciTech Connect

    Sakamoto, M.; Nakano, A.

    1995-10-01

    Several animal studies have indicated that a developing organism in its prenatal and early postnatal stage may be at higher risk in toxic metal exposure than in adult stage. Many infants were congenitally affected by methylmercury in the epidemics in Japan and Iraq. The infants reported from Minamata, Japan, had severe cerebral palsy, whereas their mothers had mild or no manifestations of poisoning. Some of the high susceptibility in infants may resulted from the specific features of the methylmercury metabolism in the developing organisms. Prenatal or postnatal development is characterized by functional immaturity of organs, which may affect the mercury (Hg) accumulation among organs. It seems possible that the Hg distribution might, in fact, reflect the toxic effects of methylmercury during a given developing phase. Thus, its distribution deserves closer examination. In our previous study, when a toxic level of methylmercury was administered, the Hg distribution and its effects on body weight gain and neurological disorders were found to be different among the rat postnatal developing phases. In the present study the Hg distribution among organs and brain regions was investigated during the several development phases with a nontoxic level of methylmercury treatment. 24 refs., 1 fig., 2 tabs.

  8. Reanalysis of dose-response data from the Iraqi methylmercury poisoning episode

    SciTech Connect

    Crump, K.; Clewell, H.; Gearhart, J.

    1995-08-01

    Applying a hockey stick parametric dose-response model to data on late or retarded development in Iraqi children exposed in utero to methylmercury, with mercury (Hg) exposure characterized by the peak Hg concentration in mothers` hair during pregnancy, Cox et al. calculated the {open_quotes}best statistical estimate{close_quotes} of the threshold for health effects as 10 ppm Hg in hair with a 95% range of uncertainty of between 0 and 13.6 ppm. A new application of the hockey stick model to the Iraqi data shows, however, that the statistical upper limit of the threshold based on the hockey stick model could be as high as 255 ppm. Futhermore, the maximum likelihood estimate of the threshold using a different parametric model is virtually zero. These and other analyses demonstrate that threshold estimates based on parametric models exhibit high statistical variability and model dependency, and are highly sensitive to the precise definition of an abnormal response. Consequently, they are not a reliable basis for setting a reference dose (RfD) for methylmercury. Benchmark analyses and statistical analyses useful for deriving NOAELs are also presented. We believe these latter analyses-particularly the benchmark analyses-generally form a sounder basis for determining RfDs than the type of hockey stick analysis presented by Cox et al. However, the acute nature of the exposures, as well as other limitations in the Iraqi data suggest that other data may be more appropriate for determining acceptable human exposures to methylmercury. 24 refs., 5 figs., 2 tabs.

  9. Hippocampal developmental vulnerability to methylmercury extends into prepubescence

    PubMed Central

    Obiorah, Maryann; McCandlish, Elizabeth; Buckley, Brian; DiCicco-Bloom, Emanuel

    2015-01-01

    The developing brain is sensitive to environmental toxicants such as methylmercury (MeHg), to which humans are exposed via contaminated seafood. Prenatal exposure in children is associated with learning, memory and IQ deficits, which can result from hippocampal dysfunction. To explore underlying mechanisms, we have used the postnatal day (P7) rat to model the third trimester of human gestation. We previously showed that a single low exposure (0.6 μg/gbw) that approaches human exposure reduced hippocampal neurogenesis in the dentate gyrus (DG) 24 h later, producing later proliferation and memory deficits in adolescence. Yet, the vulnerable stem cell population and period of developmental vulnerability remain undefined. In this study, we find that P7 exposure of stem cells has long-term consequences for adolescent neurogenesis. It reduced the number of mitotic S-phase cells (BrdU), especially those in the highly proliferative Tbr2+ population, and immature neurons (Doublecortin) in adolescence, suggesting partial depletion of the later stem cell pool. To define developmental vulnerability to MeHg in prepubescent (P14) and adolescent (P21) rats, we examined acute 24 h effects of MeHg exposure on mitosis and apoptosis. We found that low exposure did not adversely impact neurogenesis at either age, but that a higher exposure (5 μg/gbw) at P14 reduced the total number of neural stem cells (Sox2+) by 23% and BrdU+ cells by 26% in the DG hilus, suggesting that vulnerability diminishes with age. To determine whether these effects reflect changes in MeHg transfer across the blood brain barrier (BBB), we assessed Hg content in the hippocampus after peripheral injection and found that similar levels (~800 ng/gm) were obtained at 24 h at both P14 and P21, declining in parallel, suggesting that changes in vulnerability depend more on local tissue and cellular mechanisms. Together, we show that MeHg vulnerability declines with age, and that early exposure impairs later

  10. DEVELOPMENTAL NEUROTOXICITY: EVALUATION OF TESTING PROCEDURES WITH METHYLAZOXYMETHANOL AND METHYLMERCURY

    EPA Science Inventory

    Testing procedures that allow for early, rapid and cost-effective investigation of potential developmental neurotoxicants were evaluated using two prototypical developmental neurotoxicants, methylazoxymethanol (MAM) and methylmercury (MeHg). valuation of offspring of Long-Evans r...

  11. Methylmercury concentrations in broiler's meat and hen's meat and eggs

    SciTech Connect

    Kambamanoli-Dimou, A. ); Kilikidis, S.; Kamarianos, A. )

    1989-05-01

    The concentration of mercury in food has been considered to present the greatest toxicological danger to the average citizen. The presence of mercury in foods has been reported in several studies. Much of the research has been carried out on total mercury concentration in foods and not on methylmercury concentration and as it is known methylmercury is the most dangerous form of mercury. Methylmercury, which is highly resistant to biodegradation, can be synthesized from any other form of mercury in the aquatic biosphere, can be bioconcentrated in the aquatic food chain and through fish-meals can be transported and concentrated in animals and their products. Such food chains, together with the various terrestrial food chains would represent a serious risk for man. This study was undertaken to determine the methylmercury levels in broiler's meat, hen's meat and eggs.

  12. Methylmercury in populations eating large quantities of marine fish

    SciTech Connect

    Turner, M.D.; Marsh, D.O.; Smith, J.C.; Inglis, J.B.; Clarkson, T.W.; Rubio, C.E.; Chiriboga, J.; Chiriboga, C.C.

    1980-11-01

    A Peruvian population was identified that was chronically exposed to methylmercury from the longterm consumption of ocean fish. The weekly fish intake averaged 10.1 kg per average family of 6.2 persons. Blood methylmercury concentrations ranged from 11 to 275 ng/ml, with a mean of 82 ng/ml. Paresthesias were reported by 29.5% of the population. In contrast, a nearby control population had a mean weekly fish consumption of 1.9 kg per average family of 6.4 persons. Their blood methylmercury levels were 3.3-25.1 ng/ml, with a mean of 9.9 ng/ml. Paresthesias were reported by 49.5% of this control group. No individual was identified with symptoms or signs that could be attributed to methylmercury intoxication.

  13. Ecological risk of methylmercury in Everglades National Park, Florida, USA.

    PubMed

    Rumbold, D G; Lange, T R; Axelrad, D M; Atkeson, T D

    2008-10-01

    Dramatic declines in mercury levels have been reported in Everglades biota in recent years. Yet, methylmercury (MeHg) hot spots remain. This paper summarizes a risk assessment of MeHg exposure to three piscivorous wildlife species (bald eagle, Haliaeetus leucocephalus; wood stork, Mycteria americana; and great egret, Ardea albus) foraging at a MeHg hot spot in northern Everglades National Park (ENP). Available data consisted of literature-derived life history parameters and tissue concentrations measured in 60 largemouth bass (Micropterus salmoides), 60 sunfish (Lepomis spp.), and three composite samples of mosquitofish (Gambusia holbrooki) collected from 2003 to 2005. To assess risk, daily MeHg intake was estimated using Monte Carlo methods and compared to literature-derived effects thresholds. The results indicated the likelihood was very high, ranging from 98-100% probability, that these birds would experience exposures above the acceptable dose when foraging in northern ENP. Moreover, the likelihood that these birds would experience exposures above the lowest-observed-adverse-effect level (LOAEL) ranged from a 14% probability for the wood stork to 56% probability for the eagle. Data from this study, along with the results from several other surveys suggest that biota in ENP currently contain the highest MeHg levels in South Florida and that these levels are similar to or greater than other known MeHg hot spots in the United States. Given these findings, this paper also outlines a strategic plan to obtain additional measured and modeled information to support risk-based management decisions in ENP. PMID:18679795

  14. Warming increases methylmercury production in an Arctic soil.

    PubMed

    Yang, Ziming; Fang, Wei; Lu, Xia; Sheng, Guo-Ping; Graham, David E; Liang, Liyuan; Wullschleger, Stan D; Gu, Baohua

    2016-07-01

    Rapid temperature rise in Arctic permafrost impacts not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) toxin that can endanger humans, as well as wildlife in terrestrial and aquatic ecosystems. Currently little is known concerning the effects of rapid permafrost thaw on microbial methylation and how SOC degradation is coupled to MeHg biosynthesis. Here we describe the effects of warming on MeHg production in an Arctic soil during an 8-month anoxic incubation experiment. Net MeHg production increased >10 fold in both organic- and mineral-rich soil layers at warmer (8 °C) than colder (-2 °C) temperatures. The type and availability of labile SOC, such as reducing sugars and ethanol, were particularly important in fueling the rapid initial biosynthesis of MeHg. Freshly amended mercury was more readily methylated than preexisting mercury in the soil. Additionally, positive correlations between mercury methylation and methane and ferrous ion production indicate linkages between SOC degradation and MeHg production. These results show that climate warming and permafrost thaw could potentially enhance MeHg production by an order of magnitude, impacting Arctic terrestrial and aquatic ecosystems by increased exposure to mercury through bioaccumulation and biomagnification in the food web. PMID:27131808

  15. Proteomic Analysis of Cerebellum in Common Marmoset Exposed to Methylmercury.

    PubMed

    Shao, Yueting; Yamamoto, Megumi; Figeys, Daniel; Ning, Zhibin; Chan, Hing Man

    2015-07-01

    The cerebellum is known as the major target regions of methylmercury (MeHg) toxicity, but the mechanisms are still not fully understood. We studied the effects of MeHg exposure in the cerebellum of common marmoset (Callithrix jacchus) using a shotgun proteomic approach with liquid chromatography coupled to mass spectrometry. A total of 1000 common proteins were identified in all samples, and 102 proteins were significantly differentially expressed in the cerebellum of common marmoset with orally dosed MeHg (1.5 mg MeHg/kg body weight for 2 weeks) compared with those of the control group. Functional enrichment analysis and pathway predictions showed that the differentially expressed proteins were involved in carbohydrate derivative metabolic process, ion transport including synaptic transmission, cell development, and calcium signaling pathway. Cellular component enrichment analysis showed that they were mainly distributed in plasma membrane, excitatory synapse, and synaptic membrane. These results indicate that synaptic transmission and calcium signaling pathways are the core functions affected by MeHg. We found a total of 21 novel proteins affected by MeHg in synaptic transmission and calcium signaling pathways. DLG4: (PSD95) and MIR-19A/MIR-19B were found to be potential key targets leading to the multiple effects of MeHg neurotoxicity. These results show the global effects of MeHg on cellular functions and pathways leading to neurological deficits in common marmoset. PMID:25809596

  16. Biochar amendment reduced methylmercury accumulation in rice plants.

    PubMed

    Shu, Rui; Wang, Yongjie; Zhong, Huan

    2016-08-01

    There is growing concern about methylmercury (MeHg) accumulation in rice grains and thus enhanced dietary exposure to MeHg in Asian countries. Here, we explored the possibility of reducing grain MeHg levels by biochar amendment, and the underlying mechanisms. Pot (i.e., rice cultivation in biochar amended soils) and batch experiments (i.e., incubation of amended soils under laboratory conditions) were carried out, to investigate MeHg dynamics (i.e., MeHg production, partitioning and phytoavailability in paddy soils, and MeHg uptake by rice) under biochar amendment (1-4% of soil mass). We demonstrate for the first time that biochar amendment could evidently reduce grain MeHg levels (49-92%). The declines could be attributed to the combined effects of: (1) increased soil MeHg concentrations, probably explained by the release of sulfate from biochar and thus enhanced microbial production of MeHg (e.g., by sulfate-reducing bacteria), (2) MeHg immobilization in soils, facilitated by the large surface areas and high organosulfur content of biochar, and (3) biodilution of MeHg in rice grains, due to the increased grain biomass under biochar amendment (35-79%). These observations together with mechanistic explanations improve understanding of MeHg dynamics in soil-rice systems, and support the possibility of reducing MeHg phytoaccumulation under biochar amendment. PMID:27045620

  17. Synergistic neurotoxicity induced by methylmercury and quercetin in mice

    PubMed Central

    Martins, Roberta de P.; Braga, Hugo de C.; da Silva, Aline P.; Dalmarco, Juliana B.; de Bem, Andreza F.; dos Santos, Adair Roberto S.; Dafre, Alcir L.; Pizzolatti, Moacir G.; Latini, Alexandra; Aschner, Michael; Farina, Marcelo

    2010-01-01

    Methylmercury (MeHg) is a highly neurotoxic pollutant, whose mechanisms of toxicity are related to its pro-oxidative properties. A previous report showed under in vivo conditions the neuroprotective effects of plants of the genus Polygala against MeHg-induced neurotoxicity. Moreover, the flavonoid quercetin, isolated from Polygala sabulosa, displayed beneficial effects against MeHg-induced oxidative damage under in vitro conditions. In this study, we sought for potential beneficial effects of quercetin against the neurotoxicity induced by MeHg in Swiss female mice. Animals were divided into six experimental groups: control, quercetin low dose (5 mg/Kg), quercetin high dose (50 mg/Kg), MeHg (40 mg/L, in tap water), MeHg + quercetin low dose, and MeHg + quercetin high dose. After the treatment (21 days), a significant motor deficit was observed in MeHg + quercetin groups. Biochemical parameters related to oxidative stress showed that the simultaneous treatment with quercetin and MeHg caused a higher cerebellar oxidative damage when compared to the individual exposures. MeHg plus quercetin elicited a higher cerebellar lipid peroxidation than MeHg or quercetin alone. The present results indicate that under in vivo conditions quercetin and MeHg cause additive pro-oxidative effects toward the mice cerebellum and that such phenomenon is associated with the observed motor deficit. PMID:19141311

  18. Phytoremediation of ionic and methylmercury pollution

    SciTech Connect

    Meagher, Richard B

    2010-04-28

    Our long-term goal is to enable highly productive plant species to extract, resist, detoxify, and sequester the toxic elemental pollutants, like the heavy metal mercury. Our current working hypothesis is that transgenic plants controlling the transport, chemical speciation, electrochemical state. volatilization, and aboveground binding of mercury will: a) tolerate mercury and grow rapidly in mercury contaminated environments; b) prevent methylmercury from entering the food chain; c) remove mercury from polluted soil and . water; and d) hyperaccumulate mercury in aboveground tissues for later harvest. Progress toward these specific aims is reported: to increase the transport of mercury into roots and to aboveground vegetative organs; to increase biochemical sinks and storage for mercury in leaves; to increase leaf cell vacuolar storage of mercury; and to demonstrate that several stacked transgenes, when functioning in concert, enhance mercury resistance and hyperaccumulation to high levels.

  19. A Physiologically-based Model for Methylmercury Uptake and Accumulation in Female American Kestrels

    EPA Science Inventory

    A physiologically-based model was developed to describe the uptake, distribution, and elimination of methylmercury in female American Kestrels (Falco sparverius). The model was adapted from established models for methylmercury in rodents. Features unique to the model include meth...

  20. In vitro characterization of the intestinal absorption of methylmercury using a Caco-2 cell model.

    PubMed

    Vázquez, Marta; Vélez, Dinoraz; Devesa, Vicenta

    2014-02-17

    Methylmercury (CH3Hg) is one of the forms of mercury found in food, particularly in seafood. Exposure to CH3Hg is associated with neurotoxic effects during development. In addition, methylmercury has been classified by the International Agency for Research on Cancer as a possible human carcinogen. Although the diet is known to be the main source of exposure, few studies have characterized the mechanisms involved in the absorption of this contaminant. The present study examines the absorption process using the Caco-2 cell line as a model of the intestinal epithelium. The results indicate that transport across the intestinal cell monolayer in an absorptive direction occurs mainly through passive transcellular diffusion. This mechanism coexists with carrier-mediated transcellular transport, which has an active component. The participation of H(+)- and Na(+)-dependent transport was observed. Inhibition tests point to the possible participation of amino acid transporters (B(0,+) system, L system, and/or y(+)L system) and organic anion transporters (OATs). Our study suggests the participation in CH3Hg absorption of transporters that have already been identified as being responsible for the transport of this species in other systems, although further studies are needed to confirm their participation in intestinal absorption. It should be noted that CH3Hg experiences important cellular acumulation (48-78%). Considering the toxic nature of this contaminant, this fact could affect intestinal epithelium function. PMID:24397474

  1. Immunofluorescence and Immunohistochemical Detection of Keratins.

    PubMed

    Stumptner, Cornelia; Gogg-Kamerer, Margit; Viertler, Christian; Denk, Helmut; Zatloukal, Kurt

    2016-01-01

    Reliable detection of keratins in tissues is important for investigating their physiological role and for using keratin expression as a biomarker in medical diagnostics. A particular challenge for the detection of keratins by immunofluorescence microscopy or immunohistochemistry relates to the fact that keratin intermediate filaments are obligatory heteropolymers, which may result in dissociation between RNA and protein expression levels in the event that the homeostasis of the expression of the proper keratin partners is disturbed. Furthermore, variable accessibility of epitopes on keratin polypeptides due to conformational changes may lead to false negative results. Preanalytical effects, such as warm/cold ischemia, fixation, tissue processing, and embedding may result in false negative or inappropriate reactions. An experimental design for how to systematically test preanalytical effects and to validate immunohistochemistry protocols is presented. This kind of evaluation should be performed for each antigen and antibody since the various epitopes recognized by antibodies may behave differently. In this context, one has to be aware that different cell structures may be affected or modified differently by various preanalytical procedures and may thus require different preanalytical and staining protocols. PMID:26795470

  2. Establishment of indirect immunofluorescence assay for rotavirus.

    PubMed

    Tao, J; Zhang, J; Liu, X; Jin, H; Jiang, C; Yin, Y

    2016-03-01

    Rotavirus infection is the most frequent cause of infantile gastroenteritis worldwide and a significant cause of death in infants and young children, following severe diarrhea and dehydration. Rotavirus vaccines are considered the most effective way to prevent rotavirus infections. In the process of developing rotavirus vaccines, it is crucial to establish a reliable and standardized method to determine vaccine titer. In this study, we developed an indirect immunofluorescence assay (IFA) to determine the infectious titer of Lanzhou lamb rotavirus (LLR) vaccine grown in MA104 cells. The activating concentration of trypsin was 1 µg/ml for healthy monolayers of MA104 cells at 100% confluence. After incubation for 18 hr, a rabbit anti-SA11 polyclonal antibody, diluted at 1:800 in PBS, was added to all wells, followed by an Alexa-488-conjugated secondary antibody diluted at 1:500 in PBS. Cells were examined with a fluorescence microscope. Our results show that IFA was more reproducible, more sensitive, simpler, and more rapid than the log 50% cell culture infectious dose-ELISA (lgCCID50-ELISA) in measuring the rotavirus vaccines. IFA provided a reliable basis for the qualitative and quantitative analysis of rotavirus, and the certification of rotavirus vaccine production. PMID:26982471

  3. Effects of embryonic methylmercury exposure on larval behavior of mummichogs

    SciTech Connect

    Zhou, T.; Weis, J.S.; Weis, P.

    1995-12-31

    Fundulus heteroclitus embryos were exposed to 5 and 10 ug/l meHg throughout development. Larvae were maintained in clean seawater and tested regularly for prey capture and predator avoidance. Experimentals captured significantly fewer prey (Artemia nauplii) than controls, although differences disappeared after about one week. However, 2-wk posthatch larvae showed significantly more miscues than controls. Differences were seen between controls from different populations. Fish from Hg-polluted Piles Creek (Linden NJ) which have impaired predation as adults, showed higher prey capture rate as larvae, although they exhibited more miscues than the reference population (from East Hampton, NY). Differences were also seen in the response to meHg: Piles Creek fish, which were previously found to be more resistant to teratogenic effects of higher concentrations of meHg, appeared to be more resistant than the reference population to these behavioral effects as well. In other studies, meHg-exposed larvae (from the reference population) swam greater distances than controls in a test of swimming performance. This difference also disappeared over time. Despite their increased swimming performance, exposed larvae were more vulnerable to predation by the grass shrimp, Palaemonetes pugio, due perhaps to their higher overall level of activity.

  4. Behavioral effects of prenatal methylmercury in rats: a parallel trial to the Collaborative Behavioral Teratology Study.

    PubMed

    Vorhees, C V

    1985-01-01

    Pregnant Sprague-Dawley rats treated with 0, 2.0 or 6.0 mg/kg of methylmercury on days 6-9 of gestation or left untreated as part of the Collaborative Behavioral Teratology Study (CBTS) were assigned to either the CBTS or Cincinnati Test protocol after birth. Offspring assigned to the Cincinnati test system were evaluated for growth, mortality, incisor eruption, eye opening, vaginal patency, surface righting, negative geotaxis, pivoting, olfactory orientation, swimming ontogeny, figure-8 activity, and complex water maze (Biel) problem solving. Methylmercury lengthened gestation, reduced maternal weight, and increased offspring preweaning mortality at the higher dose. This dose also accelerated upper and lower incisor eruption and delayed vaginal patency development. The high dose produced a non-significant reduction in offspring weight from shortly after birth to 30 days of age, and a significant reduction in weight by 60 days of age. This dose caused a significant delay in surface righting development and swimming ontogeny, while the low dose accelerated negative geotaxis turning and swimming angle development. The high dose reduced postweaning figure-8 activity, increased Biel water maze time, errors, and proportion of trial failures (no escape within 6 min), although the effect on errors was not significant. It was concluded that at the doses and exposure period used here, methylmercury was confirmed to be a potent behavioral teratogen using the Cincinnati test system. This finding is in agreement with the results obtained with the same treatment regimen in the CBTS. Two tests from the Cincinnati test system, swimming ontogeny and Biel maze, provided evidence that they would significantly improve the detection power of the CBTS test battery. PMID:3835472

  5. Methylmercury formation in a wetland mesocosm amended with sulfate.

    PubMed

    Harmon, S M; King, J K; Gladden, J B; Chandler, G T; Newman, L A

    2004-01-15

    This study used an experimental model to evaluate methylmercury accumulation when the soil of a constructed wetland is amended with sulfate. The model was planted with Schoenoplectus californicus and designed to reduce wastestream metals and metal-related toxicity. The soil was varied during construction to provide a control and two sulfate treatments which were equally efficient at overall mercury and copper removal. After an initial stabilization period, methylmercury concentrations in porewater were up to three times higher in the sulfate-treated porewater (0.5-1.6 ng/L) than in the control (<0.02-0.5 ng/L). Mean percent methylmercury was 9.0% in the control with 18.5 and 16.6% in the low- and high-sulfate treatments, respectively. Methylmercury concentrations measured in mesocosm surface water did not reflect the differences between the control and the sulfate treatments that were noted in porewater. The mean bulk sediment methylmercury concentration in the top 6 cm of the low-sulfate treatment (2.33 ng/g) was significantly higher than other treatment means which ranged from 0.96 to 1.57 ng/g. Total mercury in sediment ranged from 20.8 to 33.4 ng/g, with no differences between treatments. Results suggest that the non-sulfate-amended control was equally effective in removing metals while keeping mercury methylation low. PMID:14750744

  6. New Evidence on Variations of Human Body Burden of Methylmercury from Fish Consumption

    PubMed Central

    Canuel, René; de Grosbois, Sylvie Boucher; Atikessé, Laura; Lucotte, Marc; Arp, Paul; Ritchie, Charles; Mergler, Donna; Chan, Hing Man; Amyot, Marc; Anderson, Robin

    2006-01-01

    Epidemiologic studies commonly use mercury (Hg) level in hair as a valid proxy to estimate human exposure to methylmercury (MeHg) through fish consumption. This study presents the results yielded by a complete data set on fish consumption habits, Hg levels in edible fish resources, and corresponding Hg accumulation in hair, gathered in three distinct communities of eastern Canada. For one of these communities, the average hair Hg concentration was 14 times less than the expected value based on calculated daily oral exposure and current knowledge of MeHg metabolism. This finding could be explained by differences in specific genetic characteristics and/or interactive effects of other dietary components. PMID:16451872

  7. Interrelationships of blood and hair mercury concentrations in a North American population exposed to methylmercury

    SciTech Connect

    Phelps, R.W.; Clarkson, T.W.

    1980-05-01

    Samples of blood and head hair were analyzed for organic and inorganic mercury from a population which consumed large amonts of fish contaminated with methylmercury. Mercury levels in newly formed hair were found to reflect those in blood with the concentration in hair being approximately 300 times that in blood. Organic and inorganic mercury levels were linearly related in both hair and blood samples, with a mean inorganic/organic ratio of 0.05 in blood and 0.21 in hair, but individual differences were found to exist. In addition, the total mercury concentration and inorganic/organic ratio in hair remained constant with time. Thus, longitudinal analysis of hair samples can provide a simple and accurate method of monitoring continuing exposure and an estimation of peak blood levels months to years after exposure.

  8. Acute toxic responses of the freshwater planarian, Dugesia dorotocephala, to methylmercury

    SciTech Connect

    Best, J.B.; Morita, M.; Ragin, J.; Best, J. Jr.

    1981-07-01

    Toxic responses of planaria to various aquatic habitat concentrations of methylmercury chloride (MMC) were investigated. One hundred percent lethality occurred within 5 h in 2 ppM MMC, 24 h in 1 ppM MMC, and 5 days in 0.5 ppM MMC. No deaths occurred in 0.2 ppM MMC over a 10 day period, however, non-lethal toxic responses were observed. Varying degrees of head resorption, progressing caudally from the snout were observed. With continuing exposure, partial head regeneration and recovery toward more normal appearance occurred by 10 days. Teratogenic effects were observed in surgical decapitation experiments. Head regeneration was retarded in 0.1 and 0.2 ppM MMC. Malformations, visible lesions, or gross behavioral abnormalities were produced by 2 week exposure of planaria to concentrations of 20 ppB MMC or lower. (RJC)

  9. Effects of dietary methylmercury on reproduction of fathead minnows

    USGS Publications Warehouse

    Hammerschmidt, C.R.; Sandheinrich, M.B.; Wiener, J.G.; Rada, R.G.

    2002-01-01

    We examined effects of dietary methylmercury (MeHg) on reproduction of fathead minnows (Pimephales promelas). Juvenile fish were fed one of four diets until sexual maturity (phase 1): a control diet (0.06 μg Hg g-1 dry weight) and three diets contaminated with MeHg at 0.88 (low), 4.11 (medium), and 8.46 μg Hg g-1 dry weight (high). At sexual maturity, male and female fish were paired, again fed one of the four diets, and allowed to reproduce (phase 2). To assess effects of MeHg during gametogenesis, some fish were fed diets during phase 2 that differed from those during phase 1. Spawning success of pairs fed the same diet during phases 1 and 2 was 75% for controls and 46%, 50%, and 36% for the low-, medium-, and high-MeHg treatments, respectively. Spawning success of pairs fed a contaminated diet during phase 1 and a control diet during phase 2 was 63%, 40%, and 14% for the low-, medium-, and high-MeHg treatments, respectively, whereas exposure to dietary MeHg only during phase 2 did not reduce spawning success. Dietary MeHg delayed spawning, and days to spawning was positively correlated with concentration of total mercury in the carcasses of test fish. MeHg reduced the instantaneous rate of reproduction of fish fed the same diets during phases 1 and 2. Both the gonadosomatic index and reproductive effort of female fish were inversely correlated with mercury in carcasses, whereas developmental and hatching success of embryos, 7-d survival, and 7-d growth of larvae were unrelated to mercury concentrations in parental fish or their diets. MeHg decreased reproduction of adult fathead minnows at dietary concentrations encountered by predatory fishes in aquatic systems with MeHg-contaminated food webs, implying that exposed fish populations could be adversely affected by this widespread contaminant.

  10. Effects of diphenyl diselenide on methylmercury toxicity in rats.

    PubMed

    Dalla Corte, Cristiane L; Wagner, Caroline; Sudati, Jéssie H; Comparsi, Bruna; Leite, Gerlania O; Busanello, Alcindo; Soares, Félix A A; Aschner, Michael; Rocha, João B T

    2013-01-01

    This study investigates the efficacy of diphenyl diselenide [(PhSe)2] in attenuating methylmercury- (MeHg-)induced toxicity in rats. Adult rats were treated with MeHg [5 mg/kg/day, intragastrically (i.g.)] and/ or (PhSe)2 [1 mg/kg/day, intraperitoneally (i.p.)] for 21 days. Body weight gain and motor deficits were evaluated prior to treatment, on treatment days 11 and 21. In addition, hepatic and cerebral mitochondrial function (reactive oxygen species (ROS) formation, total and nonprotein thiol levels, membrane potential (ΔΨm), metabolic function, and swelling), hepatic, cerebral, and muscular mercury levels, and hepatic, cerebral, and renal thioredoxin reductase (TrxR) activity were evaluated. MeHg caused hepatic and cerebral mitochondrial dysfunction and inhibited TrxR activity in liver (38,9%), brain (64,3%), and kidney (73,8%). Cotreatment with (PhSe)2 protected hepatic and cerebral mitochondrial thiols from depletion by MeHg but failed to completely reverse MeHg's effect on hepatic and cerebral mitochondrial dysfunction or hepatic, cerebral, and renal inhibition of TrxR activity. Additionally, the cotreatment with (PhSe)2 increased Hg accumulation in the liver (50,5%) and brain (49,4%) and increased the MeHg-induced motor deficits and body-weight loss. In conclusion, these results indicate that (PhSe)2 can increase Hg body burden as well as the neurotoxic effects induced by MeHg exposure in rats. PMID:24459674

  11. Occurrence of methylmercury in Lake Valencia, Venezuela

    SciTech Connect

    Jaffe, R.; Cai, Y.; West-Thomas, J.

    1997-12-31

    The presence of mercury in the environment has received renewed attention during recent years. This is in part due to the known human health and ecological effects of the highly toxic organomercury compounds, and to the fact that novel and improved analytical techniques such as atomic fluorescence spectroscopy (AFS) and capillary chromatography with AFS detection, have enhanced significantly the detection of trace amounts of mercury and organo mercurials in environmental samples. Such techniques have allowed for a better understanding of the biogeochemical cycle of mercury in the aquatic environment. This paper reports on the presence of methylmercury in the water column and sediments of a hyper-eutrophic lake. Lake Valencia is a freshwater lake located in North-Central Venezuela`s Aragua Valley. The lake`s surface area covers approximately 350 km{sup 2}, with a mean depth of 19 m and a maximum depth of 41 m. Due to the discharge of waste waters from the cities of Maracay and Valencia, as well as from other smaller villages and agricultural areas in its watershed, Lake Valencia has become hyper-eutrophic. The population of phytoplankton, particularly of blue-green algae, has increased dramatically during the last two decades resulting in anoxic conditions in the lower part of the water column during most of the year. In addition, concentrations of anthropogenic chemicals, including heavy metals, have increased in the Lake during the last four decades. 15 refs., 2 figs.

  12. Neurotoxic effects of low-level methylmercury contamination in the Amazonian basin

    SciTech Connect

    Lebel, J.; Mergler, D.; Lucotte, M.; Larribe, F.; Dolbec, J.; Branches, F.; Amorim, M.

    1998-10-01

    Many studies have demonstrated mercury contamination in the Amazonian ecosystem, particularly in fish, a dietary mainstay of populations in this region. The present study focused on potential health effects of this low-level methylmercury exposure. The study was carried out in a village on the Tapajos River, a tributary of the Amazon, on 91 adults inhabitants whose hair mercury levels were inferior to 50 {micro}/g. Performance on a neurofunctional test battery and clinical manifestations of nervous system dysfunction were examined in relation to hair mercury concentrations. Near visual contrast sensitivity and manual dexterity, adjusted for age, decreased significantly with hair mercury levels (P < 0.05), while there was a tendency for muscular fatigue to increase and muscular strength to decrease in women. For the most part, clinical examinations were normal, however, hair mercury levels were significantly higher (P < 0.05) for persons who presented disorganized movements on an alternating movement task and for persons with restricted visual fields. These results suggest dose-dependent nervous system alterations at hair mercury levels below 50 {micro}g/g, previously considered a threshold for clinical effects. The profile of dysfunction in this adult population is consistent with the current knowledge on methylmercury poisoning. The long-term implications of these findings are unknown and need to be addressed.

  13. The Chemical Nature of Mercury in Human Brain Following Poisoning or Environmental Exposure

    PubMed Central

    2010-01-01

    Methylmercury is among the most potentially toxic species to which human populations are exposed, both at high levels through poisonings and at lower levels through consumption of fish and other seafood. However, the molecular mechanisms of methylmercury toxicity in humans remain poorly understood. We used synchrotron X-ray absorption spectroscopy (XAS) to study mercury chemical forms in human brain tissue. Individuals poisoned with high levels of methylmercury species showed elevated cortical selenium with significant proportions of nanoparticulate mercuric selenide plus some inorganic mercury and methylmercury bound to organic sulfur. Individuals with a lifetime of high fish consumption showed much lower levels of mercuric selenide and methylmercury cysteineate. Mercury exposure did not perturb organic selenium levels. These results elucidate a key detoxification pathway in the central nervous system and provide new insights into the appropriate methods for biological monitoring. PMID:22826746

  14. Mechanisms of methylmercury transport across the blood-brain barrier

    SciTech Connect

    Kerper, L.E.

    1993-01-01

    Methylmercury readily enters the brain of exposed individuals, and is highly neurotoxic. The goal of this research was to determine the mechanisms of methylmercury transport across both the luminal and abluminal membranes of brain capillary endothelial cells, the cells which comprise the blood-brain barrier. The rapid carotid injection technique was used in rats to investigate the uptake of methylmercury from blood into brain endothelial cells. Uptake of ([sup 203]Hg)-methylmercury complexed with L-cysteine (CH[sub 3] [sup 203]Hg-L-Cys) was more rapid than that of ([sup 203]Hg)-methylmercury complexed with D-cysteine or bovine serum albumin. Uptake of CH[sub 3][sup 203]Hg-L-Cys was saturable, and was inhibited by substrates for the L (alanine-preferring) carrier. Brain uptake of [sup 14]C-L-methionine was inhibited by CH[sub 3]Hg-L-Cys but not by CH[sub 3]HgCl. Uptake of [sup 203]Hg administered as CH[sub 3]Hg-L-Cys-glutathione (CH[sub 3][sup 203]Hg-GSH) was comparable to CH[sub 3][sup 203]Hg-L-Cys uptake at 2 [mu]M. L-Methionine and 2-aminobicyclo-(2,2,1)-heptane-2-carboxylic acid (BCH) inhibited [sup 203]Hg uptake administered as CH[sub 3][sup 203]Hg-GSH, whereas acivicin had no effect. This uptake was also inhibited by S-ethylglutathione when pH of the injection solution was allowed to rise to 8.5. In later experiments performed at pH 8.2, uptake of [sup 203]Hg administered as CH[sub 3][sup 203]Hg-GSH was inhibited only by BCH. To study mechanisms of methylmercury efflux from endothelial cells, a primary culture of bovine brain capillary endothelial cells was developed. Intracellular glutathione concentration was 2.6 [+-] 0.7 mM. Incubation of CH[sub 3][sup 203]HgCl-preloaded cells with GSH depletors decreased ([sup 203]Hg)-methylmercury efflux in a dose-dependent manner which correlated with intracellular GSH concentrations. ([sup 203]Hg)-Methylmercury efflux was also inhibited by GSH-S-conjugates an GSH analogs, but not by amino acids.

  15. Rapid diagnosis of mumps virus infections by immunofluorescence methods.

    PubMed

    Lennette, D A; Emmons, R W; Lennette, E H

    1976-08-01

    Mumps and its complications, particularly meningoencephalitis, is an important disease problem, and more rapid diagnostic methods are desirable. A study was made of immunofluorescence methods for the early detection of mumps virus isolated in cell cultures, or adsorbed directly from clinical specimens onto guinea pig erythrocytes. A specific diagnosis could be made in hours to 2 or 3 days utilizing immunofluorescence methods, in contrast to about 6 days by standard methods. Details of the direct immunofluorescence methods are presented, to encourage wider application in clinical virology laboratories. PMID:787002

  16. Microwave oven-based technique for immunofluorescent staining of paraffin-embedded tissues

    PubMed Central

    Buggs, Colleen

    2011-01-01

    Immunohistochemical analysis of formalin-fixed paraffin-embedded tissues can be challenging due to potential modifications of protein structure by exposure to formalin. Heat-induced antigen retrieval techniques can reverse reactions between formalin and proteins that block antibody recognition. Interactions between antibodies and antigens are further enhanced by microwave irradiation, which has simplified immunohistochemical staining protocols. In this report, we modify a technique for antigen retrieval and immunofluorescent staining of formalin-fixed paraffin-embedded tissues by showing that it works well with several antibodies and buffers. This microwave-assisted method for antigen retrieval and immunofluorescent staining eliminates the need for blocking reagents and extended washes, which greatly simplifies the protocol allowing one to complete the analysis in less than 3 h. PMID:17653827

  17. The immunofluorescence techniques in the diagnosis of endocrine autoimmune diseases.

    PubMed

    Betterle, Corrado; Zanchetta, Renato

    2012-08-01

    In the study of autoimmune diseases, the laboratory plays a very important role. We describe the immunofluorescence techniques (direct, indirect, complement-fixing, double) for determining the presence of autoantibodies and their role in the autoimmune endocrine diseases. PMID:26000129

  18. Flow cytometric immunofluorescence of rat anterior pituitary cells

    NASA Technical Reports Server (NTRS)

    Hatfield, J. Michael; Hymer, W. C.

    1985-01-01

    A flow cytometric immunofluorescence technique was developed for the quantification of growth hormone, prolactin, and luteinizing hormone producing cells. The procedure is based on indirect-immunofluorescence of intracellular hormone using an EPICS V cell sorter and can objectively count 50,000 cells in about 3 minutes. It can be used to study the dynamics of pituitary cell populations under various physiological and pharmacological conditions.

  19. Development of an immunofluorescence focus assay for Ebola virus.

    PubMed Central

    Truant, A L; Regnery, R L; Kiley, M P

    1983-01-01

    A 48-h indirect immunofluorescence focus assay for the quantitation of Ebola virus was developed, utilizing HeLa-229 cell monolayers. The dose dependency and the sensitivity of this assay as compared with conventional assays are reported. This indirect immunofluorescence focus assay can be used as a rapid, quantitative test for the detection of Ebola virus, an agent from Africa known to cause hemorrhagic fever. Images PMID:6352735

  20. A Physiologically Based Model for Methylmercury in Female American Kestrels

    EPA Science Inventory

    A physiologically based toxicokinetic (PBTK) model was developed to describe the uptake, distribution, and elimination of methylmercury (CH3Hg) in female American kestrels. The model consists of six tissue compartments corresponding to the brain, liver, kidney, gut, red blood cel...

  1. Transfer of methylmercury to hens' eggs after oral administration

    SciTech Connect

    Kambamanoli-Dimou, A. ); Kamarianos, A.; Kilikidis, S. )

    1991-01-01

    The present investigation was performed to elucidate the possibility of transport of methylmercury into eggs after its oral administration. Also, to determine the quantity of mercury excreted via eggs after oral administration of a certain quantity of this element once or in doses.

  2. The Engineered Phytoremediation of Ionic and Methylmercury Pollution

    SciTech Connect

    Richard Meagher; Sarah Marshburn; Andrew Heaton; Anne Marie Zimer; Raoufa Rahman

    2003-06-24

    Our current specific objectives are to use transgenic plants to control the chemical species, electrochemical state, and above ground binding of mercury to (a) prevent methylmercury from entering the food-chain, (b) remove mercury from polluted sites, and (c) hyperaccumulate mercury in above ground tissues for later harvest.

  3. Biomagnifications of mercury and methylmercury in tuna and mackerel.

    PubMed

    Hajeb, P; Jinap, S; Ahmad, I

    2010-12-01

    Seawater may be contaminated by harmful substances, including toxic elements released by human activities. The present study evaluates the total mercury and methylmercury concentrations and their correlations to fish body size in longtail tuna and short-bodied mackerel from Chendring, Kuantan, at east coast and Kuala Perlis at west costs of Peninsular Malaysia during May to November 2007. Total mercury and methylmercury in muscle tissue of 69 samples of longtail tuna and short-bodied mackerel, ranged from 0.180 to 1.460 μg/g and 0.0.169-0.973 μg/g and 0.251-1.470 μg/g and 0.202-1.352, whereas the methylmercury to total mercury ratio ranged from 70% to 83%, respectively. Samples of both species from the east coast showed higher levels of mercury compared to those from west coast. In all of the locations, significant positive correlations were found between fish body weight and mercury content (R(2) > 0.470). The estimated weekly intake of total mercury and methylmercury from the consumption 66.33 g/week of short-bodied mackerel and 18.34 g/week of longtail tuna (based on local dietry survey) was found to be lower than the maximum limit of 5 and 1.5 μg/kg bodyweight established by FAO/WHO and codex, respectively. PMID:20041345

  4. BACTERIAL METHYLMERCURY DEGRADATION IN FLORIDA EVERGLADES PEAT SEDIMENT

    EPA Science Inventory

    Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying 14CH4 and 14CO2 production after incubation of anaerobic sediments with [14C]MeHg. Degradation rate constants (k) were consistently <=0.1 d-1 and decreased ...

  5. Photolytic degradation of methylmercury enhanced by binding to natural organic ligands

    NASA Astrophysics Data System (ADS)

    Zhang, Tong; Hsu-Kim, Heileen

    2010-07-01

    Methylmercury is a neurotoxin that accumulates in food webs and poses a significant risk to human health. In natural water bodies, methylmercury concentrations remain low due to the degradation of methylmercury into inorganic mercury by sunlight, a process known as photodecomposition. Rates of photodecomposition are relatively rapid in freshwater lakes, and slow in marine waters, but the cause of this difference is not clear. Here, we carry out incubation experiments with artificial freshwater and seawater samples to examine the mechanisms regulating methylmercury photodecomposition. We show that singlet oxygen-a highly reactive form of dissolved oxygen generated by sunlight falling on dissolved organic matter-drives photodecomposition. However, in our experiments the rate of methylmercury degradation depends on the type of methylmercury-binding ligand present in the water. Relatively fast degradation rates (similar to observations in freshwater lakes) were detected when methylmercury species were bound to sulphur-containing ligands such as glutathione and mercaptoacetate. In contrast, methylmercury-chloride complexes, which are the dominant form of methylmercury in marine systems, did not degrade as easily. Our results could help to explain why methylmercury photodecomposition rates are relatively rapid in freshwater lakes and slow in marine waters.

  6. Mercury dynamics in hair of rats exposed to methylmercury by synchrotron radiation X-ray fluorescence imaging

    SciTech Connect

    Shimojo, Nobuhiro; Homma-Takeda, Shino; Kumagai, Yoshito

    1997-05-02

    Two dimensional distribution of mercury (Hg) in hair samples of rats exposed to methylmercury (MeHg) was analyzed by synchrotron radiation X-ray fluorescence (SR-XRF) imaging. Experiments with endogenous- and exogenous-model for MeHg exposure revealed that the metal level was obviously higher in the hair cortex after the former exposure whereas a dominant site that Hg distributed after the latter exposure was the cuticle. The method also provided us the Hg profile along the hair length with a single hair obtained by the endogenous model. Thus application of SR-XRF analysis to hair sample would facilitate biological monitoring to not only distinct Hg exposure but also determine its dynamics with only the specimen. 12 refs., 7 figs.

  7. Abiotic production of methylmercury by solar radiation.

    PubMed

    Siciliano, Steven D; O'Driscoll, Nelson J; Tordon, Robert; Hill, Jonathan; Beauchamp, Stephen; Lean, David R S

    2005-02-15

    Methylmercury [MeHg(I) in the aerobic surface water of lakes is thought to be rapidly degraded, but contrary to expectations, we show that MeHg(I) concentrations often increase during sunlight hours or remain relatively constant. We hypothesized that there were water column processes that generated MeHg(I) and that these processes were linked to dissolved organic matter (DOM) and solar radiation. A 2-day diurnal pattern of MeHg(I) in surface water with corresponding bottled controls was assessed for two contrasting lakes in Kejimikujik, Nova Scotia, Canada. Following this study, a tangential ultrafiltrator was used to size-fractionate and generate a concentration gradient of DOM from four different lakes located near Lac Berthelot, Quebec, Canada. The watersheds of two of these lakes were not substantially logged whereas the other two had been extensively logged. Different size fractions of DOM as well as different concentrations of DOM were exposed to sunlight for varying periods of time. We observed that, in Keiimikujik, the concentration of MeHg(I) in surface waters peaked in the early afternoon. Furthermore, this also occurred in bottled water for one of the lakes, Puzzle, eliminating the possibility that in-lake mixing played a role in this pattern. The formation of MeHg(I) was found to be dependent on the size fraction and amount of DOM present in the water. Specifically, DOM less than 5 kDa or between 30 and 300 kDa generated MeHg(I) when exposed to sunlight, but larger fractions did not. Furthermore, although data are limited, we found that water from lakes with logged watersheds generated MeHg(I) when exposed to sunlight, whereas water from lakes with low levels of logging in the undisturbed watersheds did not. Our results demonstrate that MeHg(I) can be formed in freshwaters of certain lakes in response to solar radiation. This photoproduction of MeHg(I) is dependent on DOM concentrations and type, with the importance of water chemistry not yet clear. The

  8. Binding Strength of Methylmercury to Aquatic NOM

    SciTech Connect

    Khwaja, A.; Bloom, P; Brezonik, P

    2010-01-01

    A competitive-ligand, equilibrium-dialysis technique using bromide measured methylmercury (MeHg{sup +}) binding to Suwannee River fulvic acid (SRFA) and NOM from a lake and a bog in Minnesota. Distribution coefficients (K{sub OC}) and stability constants (K{prime}) varied only slightly over a range of [Br{sup -}] and ratios of MeHg{sup +} to reduced sulfur, S{sub re}, the putative NOM binding site. For SRFA at pH 3.0, K{sub OC} ranged from 10{sup 7.7} to 10{sup 8.2} and K{prime} ranged from 10{sup 15.5} to 10{sup 16.0} over MeHg{sup +}:S{sub re} ratios from 1:1220 to 1:12200 (well below S{sub re} saturation). The importance of pH depends on the calculation model for binding constants. Over pH 2.98-7.62, K{sub OC} had little pH dependence (slope = 0.2; r{sup 2} = 0.4; range 10{sup 7.7}-10{sup 9.1}), but K{prime} calculated using thiol ligands with pK{sub a} = 9.96 had an inverse relationship (slope = -0.8; r{sup 2} = 0.9; range 10{sup 15.6}-10{sup 12.3}). A pH-independent model was obtained only with thiol pK{sub a} {le} 4. The mean K{prime}{sub 4} for SRFA (K{prime} with thiol pK{sub a} = 4.2) was 10{sup 9.8} (range 10{sup 9.11}-10{sup 10.27}) and small slope (0.02). Similar values were found for Spring Lake NOM; bog S2 NOM had values one-tenth as large. These constants are generally similar to published values; differences reflect variations in methods, pH, types of NOM, and calculation models.

  9. Neurodevelopment of Amazonian children exposed to ethylmercury (from Thimerosal in vaccines) and methylmercury (from fish).

    PubMed

    Marques, Rejane C; Abreu, Luciana; Bernardi, José V E; Dórea, José G

    2016-08-01

    Few studies have addressed co-occurring methylmercury (MeHg) from maternal origin and ethylmercury (EtHg) from Thimerosal-containing vaccines (TCVs) during infant's neurodevelopment. We studied children (n=1139) from the Western Amazon based on combined (low, intermediate, and high) exposure to chronic MeHg from fish consumption and acute TCV- EtHg. Neurodevelopment outcomes were age of walking and age of talking, and the Bayley Scale of Infant Development (BSID). The Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI) were measured at six and 24 months of age. Median hair-Hg (HHg) at birth was 6.4µgg(-1) in mothers, and 1.94µgg(-1) in newborns; total (pregnancy and infancy) EtHg exposure ranged from 0 to 187.5µg. The combined (MeHg+EtHg) exposure showed significant differences for MDI but not for PDI; however, there was a significant decrease in both MDI and PDI scores at 24 months. The increase in BSID delays (scores <80) between six and 24 months was not discernible with regards to EtHg or MeHg exposure. We found a statistically significant increase in neurodevelopmental (BSID) delays related to the combined exposure to Hg (MeHg>EtHg). Neurodevelopment delays due to low-doses of organic mercury (albeit undiscernible) are not predictable but can be avoided by choosing low-Hg fish and providing Thimerosal-free vaccines. PMID:26774584

  10. Methylmercury risk and awareness among American Indian women of childbearing age living on an inland northwest reservation

    SciTech Connect

    Kuntz, Sandra W.; Hill, Wade G.; Linkenbach, Jeff W.; Lande, Gary; Larsson, Laura

    2009-08-15

    American Indian women and children may be the most overrepresented among the list of disparate populations exposed to methylmercury. American Indian people fish on home reservations where a state or tribal fishing license (a source of advisory messaging) is not required. The purpose of this study was to examine fish consumption, advisory awareness, and risk communication preferences among American Indian women of childbearing age living on an inland Northwest reservation. For this cross-sectional descriptive study, participants (N=65) attending a Special Supplemental Nutrition Program for Women, Infants, and Children (WIC) clinic were surveyed between March and June 2006. An electronic questionnaire adapted from Anderson et al. (2004) was evaluated for cultural acceptability and appropriateness by tribal consultants. Regarding fish consumption, approximately half of the women surveyed (49%) indicated eating locally caught fish with the majority signifying they consumed medium- and large-size fish (75%) that could result in exposure to methylmercury. In addition, a serendipitous discovery indicated that an unanticipated route of exposure may be fish provided from a local food bank resulting from sportsman's donations. The majority of women (80%) were unaware of tribal or state fish advisory messages; the most favorable risk communication preference was information coming from doctors or healthcare providers (78%). Since the population consumes fish and has access to locally caught potentially contaminated fish, a biomonitoring study to determine actual exposure is warranted.

  11. Species differences in the sensitivity of avian embryos to methylmercury

    USGS Publications Warehouse

    Heinz, G.H.; Hoffman, D.J.; Klimstra, J.D.; Stebbins, K.R.; Kondrad, S.L.; Erwin, C.A.

    2009-01-01

    We injected doses of methylmercury into the air cells of eggs of 26 species of birds and examined the dose-response curves of embryo survival. For 23 species we had adequate data to calculate the median lethal concentration (LC50). Based on the dose-response curves and LC50s, we ranked species according to their sensitivity to injected methylmercury. Although the previously published embryotoxic threshold of mercury in game farm mallards (Anas platyrhynchos) has been used as a default value to protect wild species of birds, we found that, relative to other species, mallard embryos are not very sensitive to injected methylmercury; their LC50 was 1.79 ug/g mercury on a wet-weight basis. Other species we categorized as also exhibiting relatively low sensitivity to injected methylmercury (their LC50s were 1 ug/g mercury or higher) were the hooded merganser (Lophodytes cucullatus), lesser scaup (Aythya affinis), Canada goose (Branta canadensis), double-crested cormorant (Phalacrocorax auritus), and laughing gull (Larus atricilla). Species we categorized as having medium sensitivity (their LC50s were greater than 0.25 ug/g mercury but less than 1 ug/g mercury) were the clapper rail (Rallus longirostris), sandhill crane (Grus canadensis), ring-necked pheasant (Phasianus colchicus), chicken (Gallus gallus), common grackle (Quiscalus quiscula), tree swallow (Tachycineta bicolor), herring gull (Larus argentatus), common tern (S terna hirundo), royal tern (Sterna maxima), Caspian tern (Sterna caspia), great egret (Ardea alba), brown pelican (Pelecanus occidentalis), and anhinga (Anhinga anhinga). Species we categorized as exhibiting high sensitivity (their LC50s were less than 0.25 ug/g mercury) were the American kestrel (Falco sparverius), osprey (Pandion haliaetus), white ibis (Eudocimus albus), snowy egret (Egretta thula), and tri-colored heron (Egretta tricolor). For mallards, chickens, and ring-necked pheasants (all species for which we could compare the toxicity of our

  12. Species differences in the sensitivity of avian embryos to methylmercury.

    PubMed

    Heinz, Gary H; Hoffman, David J; Klimstra, Jon D; Stebbins, Katherine R; Kondrad, Shannon L; Erwin, Carol A

    2009-01-01

    We injected doses of methylmercury into the air cells of eggs of 26 species of birds and examined the dose-response curves of embryo survival. For 23 species we had adequate data to calculate the median lethal concentration (LC(50)). Based on the dose-response curves and LC(50)s, we ranked species according to their sensitivity to injected methylmercury. Although the previously published embryotoxic threshold of mercury in game farm mallards (Anas platyrhynchos) has been used as a default value to protect wild species of birds, we found that, relative to other species, mallard embryos are not very sensitive to injected methylmercury; their LC(50 )was 1.79 microg/g mercury on a wet-weight basis. Other species we categorized as also exhibiting relatively low sensitivity to injected methylmercury (their LC(50)s were 1 microg/g mercury or higher) were the hooded merganser (Lophodytes cucullatus), lesser scaup (Aythya affinis), Canada goose (Branta canadensis), double-crested cormorant (Phalacrocorax auritus), and laughing gull (Larus atricilla). Species we categorized as having medium sensitivity (their LC(50)s were greater than 0.25 microg/g mercury but less than 1 microg/g mercury) were the clapper rail (Rallus longirostris), sandhill crane (Grus canadensis), ring-necked pheasant (Phasianus colchicus), chicken (Gallus gallus), common grackle (Quiscalus quiscula), tree swallow (Tachycineta bicolor), herring gull (Larus argentatus), common tern (Sterna hirundo), royal tern (Sterna maxima), Caspian tern (Sterna caspia), great egret (Ardea alba), brown pelican (Pelecanus occidentalis), and anhinga (Anhinga anhinga). Species we categorized as exhibiting high sensitivity (their LC(50)s were less than 0.25 microg/g mercury) were the American kestrel (Falco sparverius), osprey (Pandion haliaetus), white ibis (Eudocimus albus), snowy egret (Egretta thula), and tri-colored heron (Egretta tricolor). For mallards, chickens, and ring-necked pheasants (all species for which we

  13. Does methylmercury have a role in causing developmental disabilities in children?

    PubMed Central

    Myers, G J; Davidson, P W

    2000-01-01

    Methylmercury (MeHg) is a potent neurotoxin that in high exposures can cause mental retardation, cerebral palsy, and seizures. The developing brain appears particularly sensitive to MeHg. Exposure levels in pregnant experimental animals that do not result in detectable signs or symptoms in the mother can adversely affect the offspring's development. Studies of human poisonings suggest this may also occur in humans. Human exposure to MeHg is primarily dietary through the consumption of fish: MeHg is present in all fresh and saltwater fish. Populations that depend on fish as a major source of dietary protein may achieve MeHg exposure levels hypothesized to adversely affect brain development. Increasing mercury levels in the environment have heightened concerns about dietary exposure and a possible role for MeHg in developmental disabilities. Follow-up studies of an outbreak of MeHg poisoning in Iraq revealed a dose-response relationship for prenatal MeHg exposure. That relationship suggested that prenatal exposure as low as 10 ppm (measured in maternal hair growing during pregnancy) could adversely affect fetal brain development. However, using the same end points as were used in the Iraq study, no associations have been reported in fish-eating populations. Using a more extensive range of developmental end points, some studies of populations consuming seafood have reported associations with prenatal MeHg exposure, whereas others have found none. This paper reviews the data presently available associating MeHg exposure with development and poses some of the unanswered questions in this field. Images Figure 1 Figure 2 PMID:10852838

  14. Immunofluorescence detection of pea protein in meat products.

    PubMed

    Petrášová, Michaela; Pospiech, Matej; Tremlová, Bohuslava; Javůrková, Zdeňka

    2016-08-01

    In this study we developed an immunofluorescence method to detect pea protein in meat products. Pea protein has a high nutritional value but in sensitive individuals it may be responsible for causing allergic reactions. We produced model meat products with various additions of pea protein and flour; the detection limit (LOD) of the method for pea flour was 0.5% addition, and for pea protein it was 0.001% addition. The repeatabilities and reproducibilities for samples both positive and negative for pea protein were all 100%. In a blind test with model products and commercial samples, there was no statistically significant difference (p > 0.05) between the declared concentrations of pea protein and flour and the immunofluorescence method results. Sensitivity was 1.06 and specificity was 1.00. These results show that the immunofluorescence method is suitable for the detection of pea protein in meat products. PMID:27441410

  15. In situ production of methylmercury within a stream channel in northern California.

    PubMed

    Tsui, Martin Tsz Ki; Finlay, Jacques C; Balogh, Steven J; Nollet, Yabing H

    2010-09-15

    Natural stream ecosystems throughout the world are contaminated by methylmercury, a highly toxic compound that bioaccumulates and biomagnifies in aquatic food webs. Wetlands are widely recognized as hotspots for the production of methylmercury and are often assumed to be the main sources of this neurotoxin in downstream ecosystems. However, many streams lacking wetlands in their drainage basins (e.g., montane and semiarid regions in the western United States) have significant methylmercury contamination, and the sources of methylmercury in these streams remain largely unknown. In this study, we observed substantial production of methylmercury within a highly productive stream channel in northern California (South Fork Eel River) within a drainage basin lacking wetlands. We found that in situ methylmercury production is positively related to phosphorus removal and water temperature within the stream channel, supporting hypothesized biological mediation of in situ mercury transformation. Moreover, our data suggest that epiphytic microbial communities on a dominant filamentous alga (Cladophora glomerata) could play a role in in situ methylmercury production. Because peak in situ methylmercury production coincides with the period of the highest biological productivity during summer baseflow, methylmercury produced internally may be efficiently routed into local stream food webs. Our study provides strong evidence that stream channels, especially those associated with high primary productivity, can be important for regulating the bioavailability and toxicity of this global contaminant. PMID:20715863

  16. Meeting Report: Methylmercury in Marine Ecosystems—From Sources to Seafood Consumers

    PubMed Central

    Chen, Celia Y.; Serrell, Nancy; Evers, David C.; Fleishman, Bethany J.; Lambert, Kathleen F.; Weiss, Jeri; Mason, Robert P.; Bank, Michael S.

    2008-01-01

    Mercury and other contaminants in coastal and open-ocean ecosystems are an issue of great concern globally and in the United States, where consumption of marine fish and shellfish is a major route of human exposure to methylmercury (MeHg). A recent National Institute of Environmental Health Sciences–Superfund Basic Research Program workshop titled “Fate and Bioavailability of Mercury in Aquatic Ecosystems and Effects on Human Exposure,” convened by the Dartmouth Toxic Metals Research Program on 15–16 November 2006 in Durham, New Hampshire, brought together human health experts, marine scientists, and ecotoxicologists to encourage cross-disciplinary discussion between ecosystem and human health scientists and to articulate research and monitoring priorities to better understand how marine food webs have become contaminated with MeHg. Although human health effects of Hg contamination were a major theme, the workshop also explored effects on marine biota. The workgroup focused on three major topics: a) the biogeochemical cycling of Hg in marine ecosystems, b) the trophic transfer and bioaccumulation of MeHg in marine food webs, and c) human exposure to Hg from marine fish and shellfish consumption. The group concluded that current understanding of Hg in marine ecosystems across a range of habitats, chemical conditions, and ocean basins is severely data limited. An integrated research and monitoring program is needed to link the processes and mechanisms of MeHg production, bioaccumulation, and transfer with MeHg exposure in humans. PMID:19079724

  17. Meeting report: Methylmercury in marine ecosystems--from sources to seafood consumers.

    PubMed

    Chen, Celia Y; Serrell, Nancy; Evers, David C; Fleishman, Bethany J; Lambert, Kathleen F; Weiss, Jeri; Mason, Robert P; Bank, Michael S

    2008-12-01

    Mercury and other contaminants in coastal and open-ocean ecosystems are an issue of great concern globally and in the United States, where consumption of marine fish and shellfish is a major route of human exposure to methylmercury (MeHg). A recent National Institute of Environmental Health Sciences-Superfund Basic Research Program workshop titled "Fate and Bioavailability of Mercury in Aquatic Ecosystems and Effects on Human Exposure," convened by the Dartmouth Toxic Metals Research Program on 15-16 November 2006 in Durham, New Hampshire, brought together human health experts, marine scientists, and ecotoxicologists to encourage cross-disciplinary discussion between ecosystem and human health scientists and to articulate research and monitoring priorities to better understand how marine food webs have become contaminated with MeHg. Although human health effects of Hg contamination were a major theme, the workshop also explored effects on marine biota. The workgroup focused on three major topics: a) the biogeochemical cycling of Hg in marine ecosystems, b) the trophic transfer and bioaccumulation of MeHg in marine food webs, and c) human exposure to Hg from marine fish and shellfish consumption. The group concluded that current understanding of Hg in marine ecosystems across a range of habitats, chemical conditions, and ocean basins is severely data limited. An integrated research and monitoring program is needed to link the processes and mechanisms of MeHg production, bioaccumulation, and transfer with MeHg exposure in humans. PMID:19079724

  18. Trace elements as paradigms of developmental neurotoxicants: Lead, methylmercury and arsenic.

    PubMed

    Grandjean, Philippe; Herz, Katherine T

    2015-01-01

    Trace elements have contributed unique insights into developmental neurotoxicity and serve as paradigms for such adverse effects. Many trace elements are retained in the body for long periods and can be easily measured to assess exposure by inexpensive analytical methods that became available several decades ago so that past and cumulated exposures could be easily characterized through analysis of biological samples, e.g. blood and urine. The first compelling evidence resulted from unfortunate poisoning events that allowed scrutiny of long-term outcomes of acute exposures that occurred during early development. Pursuant to this documentation, prospective studies of children's cohorts that applied sensitive neurobehavioral methods supported the notion that the brain is uniquely vulnerable to toxic damage during early development. Lead, methylmercury, and arsenic thereby serve as paradigm neurotoxicants that provide a reference for other substances that may have similar adverse effects. Less evidence is available on manganese, fluoride, and cadmium, but experience from the former trace elements suggest that, with time, adverse effects are likely to be documented at exposures previously thought to be low and safe. PMID:25175507

  19. Impact of dietary selenium on methylmercury toxicity in juvenile Atlantic cod: a transcriptional survey.

    PubMed

    Olsvik, Pål A; Amlund, Heidi; Sæle, Øystein; Ellingsen, Ståle; Skjaerven, Kaja H

    2015-02-01

    Selenium (Se) and its derivatives are known to have protective effects against mercury (Hg) toxicity in mammals. In this study we wanted to evaluate whether Se co-exposure affect the transcription of methylmercury (MeHg) toxicity-relevant genes in early life stages of fish. Juvenile Atlantic cod were exposed to regular feed (control), Se-spiked feed (3mg Se kg(-1)), MeHg-spiked feed (10mg Hg kg(-1)) or to Se- and MeHg-spiked feed (3mg Se kg(-1) and 10mg Hg kg(-1), respectively) for ten weeks. Liver tissue was harvested for transcriptional analysis when the fish were weighing 11.4 ± 3.2g. Accumulated levels of Hg in liver of the two groups of fish exposed to MeHg were 1.5mg Hg kg(-1) wet weight, or 44-fold higher than in the control group, while the Se concentrations differed with less than 2-fold between the fish groups. Selenium co-exposure had no effect on the accumulated levels of Hg in liver tissue; however, MeHg co-exposure reduced the accumulated level of Se. Dietary exposure to MeHg had no effect on fish growth. Interaction effects between Se and MeHg exposure were observed for the transcriptional levels of CAT, GPX1, GPX3, NFE2L2, UBA52, SEPP1 and DNMT1. Significant effects of MeHg exposure were seen for DNMT1 and PPARG, while effects of Se exposure were seen for GPX4B and SEPP1A, as well as for DNA methyltransferase activity. The transcriptional results suggest, by considering up-regulation as a proxy for negative impact and at the tested concentrations, a pro-oxidative effect of Se co-exposure with MeHg, rather than an antioxidative effect. PMID:25062025

  20. Accumulation of dietary methylmercury in the testes of the adult brown norway rat: Impaired testicular and epididymal function

    SciTech Connect

    Friedmann, A.S.; Chen, H.; Zirkin, B.R.; Rabuck, L.D.

    1998-05-01

    The widespread consumption of fish containing elevated concentrations of methylmercury has prompted concern over the health effects of such a diet. Previous studies with rodents have indicated that exposure to dietary mercury (Hg) impairs male reproductive health. However, adverse effects were observed following doses in the range of milligrams per kilogram of body weight, whereas typical human consumption in the United States is in the range of micrograms per kilogram of body weight. This study examined the effects of dietary Hg on male rats using levels of the metal that are more similar to those typically consumed by humans. For 19 weeks, adult male Brown Norway rats were administered methylmercury twice weekly at 0.8, 8.0, or 80 {micro}g/kg. Intratesticular testosterone levels in the high-dose group were reduced by 44$, suggesting that steroidogenesis in these animals was dramatically impaired. Although sperm production was not significantly affected, numbers of sperm in the cauda epididymides of the high-dose group were reduced by 17%. Furthermore, there was a negative correlation between fertility and testicular Hg content. These results raise the possibility that exposure to Hg at levels consumed by humans may result in steroidogenic impairment, reduced sperm counts, and fertility problems.

  1. Teratogenic efects of injected methylmercury on avian embryos

    USGS Publications Warehouse

    Heinz, Gary H.; Hoffman, David J.; Klimstra, Jon D.; Stebbins, Katherine R.; Kondrad, Shannon L.; Erwin, Carol A.

    2011-01-01

    Controlled laboratory studies with game farm mallards (Anas platyrhynchos) and chickens (Gallus gallus) have demonstrated that methylmercury can cause teratogenic effects in birds, but studies with wild species of birds are lacking. To address this need, doses of methylmercury chloride were injected into the eggs of 25 species of birds, and the dead embryos and hatched chicks were examined for external deformities. When data for controls were summed across all 25 species tested and across all types of deformities, 24 individuals out of a total of 1,533 (a rate of 1.57%) exhibited at least one deformity. In contrast, when data for all of the mercury treatments and all 25 species were summed, 188 deformed individuals out of a total of 2,292 (8.20%) were found. Some deformities, such as lordosis and scoliosis (twisting of the spine), misshapen heads, shortening or twisting of the neck, and deformities of the wings, were seldom observed in controls but occurred in much greater frequency in Hg-treated individuals. Only 0.59% of individual control dead embryos and hatchlings exhibited multiple deformities versus 3.18% for Hg-dosed dead embryos and hatchlings. Methylmercury seems to have a widespread teratogenic potential across many species of birds.

  2. Net methylmercury production in 2 contrasting stream sediments and associated accumulation and toxicity to periphyton.

    PubMed

    Klaus, Jaclyn E; Hammerschmidt, Chad R; Costello, David M; Burton, G Allen

    2016-07-01

    Periphyton uptake of bioaccumulative methylmercury (MeHg) may be an important entryway into the food web of many stream ecosystems where periphyton can be dominant primary producers. The net production of MeHg in stream sediment, its bioaccumulation in periphyton, and the potential toxicity of divalent Hg (Hg[II]) and MeHg in sediment to periphyton were investigated with a 67-d in situ incubation experiment using chemical exposure substrates containing either a fine-grained, organic-rich or a sandy, low-organic sediment, each amended with varying concentrations of mercuric chloride. Methylmercury was produced in sediment, and concentrations increased with greater amounts of added Hg(II); however, the net production of MeHg was inhibited in the highest Hg(II) treatments of both sediments. The range of total Hg concentrations that inhibited MeHg production was between approximately 80 000 ng Hg and 350 000 ng Hg per gram of organic matter for both sediments. Periphyton colonizing substrates accumulated MeHg in proportion to the concentration in sediment, but periphyton exposed to the sandy sediment accumulated approximately 20-fold more than those exposed to the organic-rich sediment relative to sediment MeHg concentrations. Toxicity of either Hg(II) or MeHg to periphyton was not observed with either periphyton organic content, net primary production, or respiration as endpoints. These results suggest that in situ production and bioaccumulation of MeHg in stream ecosystems can vary as a function of sediment characteristics and Hg(II) loadings to the sediment. Environ Toxicol Chem 2016;35:1759-1765. © 2015 SETAC. PMID:26636557

  3. An immunofluorescence assay to detect soybean rust urediniospores

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An indirect immunofluorescence assay (IF) was developed to detect urediniospores of Phakopsora pachyrhizi and P. meibomiae, utilizing rabbit polyclonal antisera produced in response to intact non-germinated (SBR1A) or germinated (SBR2) urediniospores of P. pachyrhizi. Both antisera were specific to ...

  4. Methods of Immunohistochemistry and Immunofluorescence: Converting Invisible to Visible.

    PubMed

    Mori, Hidetoshi; Cardiff, Robert D

    2016-01-01

    Observing changes in pathophysiological tissue samples often relies on immunohistochemical or immunofluorescence analysis. These techniques show target microanatomy by visualizing marker molecules on cells and their microenvironment. Here, we describe the "pros and cons" in each method, along with alternative procedures and the suggested imaging equipment. PMID:27581010

  5. Immunofluorescence Microscopy of Schizosaccharomyces pombe Using Chemical Fixation.

    PubMed

    Hagan, Iain M

    2016-01-01

    Establishing the subcellular distribution of molecules of interest and the dynamics of their spatial control underpins all areas of cell and developmental biology. Although the ability to monitor the distribution of fluorescent fusion proteins has revolutionized cell and developmental biology, indirect immunofluorescence microscopy of fixed samples remains an essential complement to this approach. Immunofluorescence is often a more appropriate approach for the study of subcellular architecture. It avoids potential artifacts caused by studying fusion proteins, which might show altered function under stressful imaging conditions. Furthermore, the quantitative analysis of multiple cells in an unperturbed population by immunofluorescence invariably provides a more accurate assessment of the spatial and temporal control of a particular process than does the analysis of individual cells that is the hallmark of live-cell imaging. Parallel studies of living and fixed cells often provide complementary data sets, both of which can be considered necessary for a comprehensive understanding of molecular function. This protocol provides a method for the visualization of the Schizosaccharomyces pombe microtubule cytoskeleton by indirect immunofluorescence microscopy following chemical fixation with formaldehyde and glutaraldehyde. It includes discussion of common modifications used to monitor the distribution of other fission yeast antigens and forms a basis from which to develop protocols to localize new molecules of interest. PMID:27371599

  6. 21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section 866.3460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3460...

  7. 21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section 866.3460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3460...

  8. 21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Mycobacterium tuberculosis immunofluorescent reagents. 866.3370 Section 866.3370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological...

  9. 21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Mycobacterium tuberculosis immunofluorescent reagents. 866.3370 Section 866.3370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological...

  10. 21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Mycobacterium tuberculosis immunofluorescent reagents. 866.3370 Section 866.3370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological...

  11. 21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section 866.3460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3460...

  12. 21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section 866.3460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3460...

  13. 21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Mycobacterium tuberculosis immunofluorescent reagents. 866.3370 Section 866.3370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological...

  14. 21 CFR 866.3370 - Mycobacterium tuberculosis immunofluorescent reagents.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Mycobacterium tuberculosis immunofluorescent reagents. 866.3370 Section 866.3370 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological...

  15. 21 CFR 866.3460 - Rabiesvirus immuno-fluorescent reagents.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Rabiesvirus immuno-fluorescent reagents. 866.3460 Section 866.3460 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES IMMUNOLOGY AND MICROBIOLOGY DEVICES Serological Reagents § 866.3460...

  16. Methylmercury-induced changes in target organs of suckling rat pups.

    PubMed

    Abdalla, Faida Husein; Bellé, Luziane Potrich; Bitencourt, Paula Eliete Rodrigues; da Silva, José Edson; Roman, Silvana; da Rosa, Cíntia; Schetinger, Maria Rosa; Moretto, Maria Beatriz

    2012-09-01

    Methylmercury (MeHg) is an organic form of mercury with toxic effects in multiple organs. The aim of the present investigation was to evaluate the in vivo effects of MeHg (1 and 4 mg/kg) given orally for seven consecutive days on adenosine deaminase (ADA), n-acetyl-β-D-glucosaminidase (NAG) and ecto-nucleoside triphosphate phosphohydrolase (NTPDase) activities, and on lipid peroxidation in hippocampus, cerebral cortex, kidney and liver of suckling rat pups. The results showed that NAG activity and lipid peroxidation levels increased in the kidney in both treatments, whereas urinary NAG activity increased only in the 1 mg/kg treatment. Despite the fact that the lipid peroxidation increased in both cerebral cortex and hippocampus, the latter appeared to be more vulnerable to MeHg exposure as it also had an increase in ADA activity. Thus, although dietary MeHg modified renal cell function, it did not alter histological features in suckling rat pups. The results of our investigation are of significant importance because they demonstrated responses to exposition to low doses of MeHg in target organs during the development of the rat. Especially the kidney was affected by the oral exposure to MeHg, suggesting the vulnerability of this organ at this stage of development. Moreover, the urinary NAG may provide important data that could serve as basis for risk assessment purposes following MeHg exposure. PMID:21194914

  17. Uptake dynamics of inorganic mercury and methylmercury by the earthworm Pheretima guillemi.

    PubMed

    Dang, Fei; Zhao, Jie; Zhou, Dongmei

    2016-02-01

    Mercury uptake dynamics in the earthworm Pheretima guillemi, including the dissolved uptake rate constant (ku) from pore-water and assimilation efficiencies (AEs) from mercury-contaminated soil, was quantified in this study. Dissolved uptake rate constants were 0.087 and 0.553 L g(-1) d(-1) for inorganic mercury (IHg) and methylmercury (MeHg), respectively. Assimilation efficiency of IHg in field-contaminated soil was 7.2%, lower than 15.4% of spiked soil. In contrast, MeHg exhibited comparable AEs for both field-contaminated and spiked soil (82.4-87.2%). Within the framework of biodynamic model, we further modelled the exposure pathways (dissolved exposure vs soil ingestion) to source the accumulated mercury in Pheretima guillemi. The model showed that the relative importance of soil ingestion to mercury bioaccumulation depended largely on mercury partitioning coefficients (K(d)), and was also influenced by soil ingestion rate of earthworms. In the examined field-contaminated soil, almost (>99%) accumulated IHg and MeHg was predicted to derive from soil ingestion. Therefore, soil ingestion should be carefully considered when assessing mercury exposure risk to earthworms. PMID:26583294

  18. Effects of environmental temperatures on the toxicity of methylmercury in rats

    SciTech Connect

    Yamaguchi, S.; Shimojo, N.; Sano, K.; Kano, K.; Hirota, Y.; Saisho, A.

    1984-05-01

    The study was designed to examine the influence of environmental temperatures on subacute (5 mg/kg/3 days) methylmercury toxicity in rats by observations of mortality, manifestation of the hindleg-crossing phenomenon, and measurement of total and methylmercury in tissue samples.

  19. A COMBINED PHYSIOLOGICAL AND BIOENERGETICS-BASED MODEL FOR METHYLMERCURY IN FEMALE AMERICAN KESTRELS

    EPA Science Inventory

    The results of this combined dose-response and modeling effort will be used to improve effects characterizations for methylmercury in avian wildlife. This information will reduce uncertainty in risk assessments for methylmercury in the environment and contribute to the developme...

  20. Maternal milk as methylmercury source for suckling mice: neurotoxic effects involved with the cerebellar glutamatergic system.

    PubMed

    Manfroi, C B; Schwalm, F D; Cereser, V; Abreu, F; Oliveira, A; Bizarro, L; Rocha, J B T; Frizzo, M E S; Souza, D O; Farina, M

    2004-09-01

    Methylmercury (MeHg) is a highly neurotoxic compound and several studies have reported intoxication signs in children whose mothers were exposed to this environmental toxicant. Although it is well established that the in utero exposure to MeHg causes neurological deficits in animals and humans, there is no evidence of the exclusive contribution of lactational exposure to MeHg as a possible cause of neurotoxicity in the offspring. In this study, we investigated the exclusive contribution of MeHg exposure through maternal milk on biochemical parameters related to the glutamatergic homeostasis (glutamate uptake by slices) and to the oxidative stress (total and nonprotein sulfhydryl groups, nonprotein hydroperoxides, glutathione peroxidase and catalase activities) in the cerebellum of suckling mice (Swiss albino). The same parameters were also evaluated in the cerebellum of mothers. Our results showed, for the first time, that lactational exposure to MeHg caused a high percent of inhibition (50%) on glutamate uptake by cerebellar slices in pups. Contrarily, this effect was not observed in mothers, which were submitted to a direct oral exposure to MeHg (15 mg/l in drinking water). In addition, behavioral/functional changes were observed in the weaning mice exposed to MeHg. It was observed an increase in the levels of nonprotein hydroperoxides in cerebellum, and this increase was negatively correlated to the glutamate uptake by cerebellar slices. This study indicates that (1) the exposure of lactating mice to MeHg causes inhibition of the glutamate uptake by cerebellar slices in the offspring; (2) this inhibitory effect seems to be related to increased levels of hydroperoxide. PMID:15201443

  1. Clinical aspects of indirect immunofluorescence for autoimmune diseases.

    PubMed

    Ghanadan, Alireza; Saghazadeh, Amene; Jahanzad, Issa; Rezaei, Nima

    2015-05-01

    Because the most common term used in conversations considering autoimmunity is autoantibodies, it is well-expected that the indirect immunofluorescence assay, which detects antibodies directed against various antigens, is one of our most impressive techniques for investigating autoimmune diseases (AIDs). Roughly speaking, the current literature corroborates that this immunopathologic investigation means that autoantibodies detection makes a considerable contribution to both diagnostic and prognostic aspects of AIDs in the clinical setting. However, it varies between different AIDs, autoantibodies, ethnicities or detection methodologies. Directly focusing on the indirect immunofluorescence assay, we present evidence to support this multidimensional variation regarding the subject via reviewing briefly the best-investigated autoantibodies in the well-documented AIDs, including vasculitis, inflammatory bowel disease, scleroderma, autoimmune hepatitis, primary biliary cirrhosis, systemic lupus erythematosus and Sjögren's syndrome. PMID:25786676

  2. Biomonitoring of Lead, Cadmium, Total Mercury, and Methylmercury Levels in Maternal Blood and in Umbilical Cord Blood at Birth in South Korea

    PubMed Central

    Kim, Yu-Mi; Chung, Jin-Young; An, Hyun Sook; Park, Sung Yong; Kim, Byoung-Gwon; Bae, Jong Woon; Han, Myoungseok; Cho, Yeon Jean; Hong, Young-Seoub

    2015-01-01

    With rising concerns of heavy metal exposure in pregnancy and early childhood, this study was conducted to assess the relationship between the lead, cadmium, mercury, and methylmercury blood levels in pregnancy and neonatal period. The study population included 104 mothers and their children pairs who completed both baseline maternal blood sampling at the second trimester and umbilical cord blood sampling at birth. The geometric mean maternal blood levels of lead, cadmium, total mercury, and methylmercury at the second trimester were 1.02 ± 1.39 µg/dL, 0.61 ± 1.51 µg/L, 2.97 ± 1.45 µg/L, and 2.39 ± 1.45 µg/L, respectively, and in the newborns, these levels at birth were 0.71 ± 1.42 µg/dL, 0.01 ± 5.31 µg/L, 4.44 ± 1.49 µg/L, and 3.67 ± 1.51 µg/L, respectively. The mean ratios of lead, cadmium, total mercury, and methylmercury levels in the newborns to those in the mothers were 0.72, 0.04, 1.76, and 1.81, respectively. The levels of most heavy metals in pregnant women and infants were higher in this study than in studies from industrialized western countries. The placenta appears to protect fetuses from cadmium; however, total mercury and methylmercury were able to cross the placenta and accumulate in fetuses. PMID:26516876

  3. RGB method in immunofluorescence investigations on stem cells

    NASA Astrophysics Data System (ADS)

    Riccio, Massimo; Resca, Elisa; Bertoni, Laura; Cavani, Francesco; Sena, Paola; Ferretti, Marzia; Baldini, Andrea; Palumbo, Carla; De Pol, Anto

    2011-03-01

    Colour is not related to a particular discipline, but it is transversely present in many circles and in almost all the aspects of life. It has a special value in art, but also as far as other disciplines are concerned, like the sciences, the colour is at the basis of some of their intrinsic significances and it often needed to allow the interpretation of some of their phenomena as well. As regards the development of cell biology knowledge, colour acquired more and more importance in revealing the observations of the researchers. A field in which the methods based on the colours are particularly employed is the immunofluorescence, used to identify specific proteins in cells and tissues. These techniques combine the fluorochrome properties with specific molecules, i.e. antibodies, directed against particular substances to investigate, for example a specific protein. In single immunofluorescence analysis, the signal from an excited fluorochrome corresponds to a particular protein. In multiple immunofluorescence analysis, two or more signals are simultaneously detected to show the localization of different proteins on the same sample. The three primary colours red, green and blue were currently assigned to the signals from immunofluorescence-processed samples and visualized by the RGB method. In the present work, different examples of RGB applications in immunocytochemical investigations are showed: the first concerns the multiple analysis of three markers, localized in different loci of the cell plasma membrane; the second is related to the co-localization of two signals in the same site of specific subcellular structures. In this case the secondary colours, obtained by overlapping the primary ones, demonstrate the specific co-presence of two proteins in the same site. With the present paper, the authors wish to underline the relevant role of colours also in those areas in which colours are the means not the end.

  4. Oxygen intrusion into anoxic fjords leads to increased methylmercury availability

    NASA Astrophysics Data System (ADS)

    Veiteberg Braaten, Hans Fredrik; Pakhomova, Svetlana; Yakushev, Evgeniy

    2013-04-01

    Mercury (Hg) appears in the oxic surface waters of the oceans at low levels (sub ng/L). Because inorganic Hg can be methylated into the toxic and bioaccumulative specie methylmercury (MeHg) levels can be high at the top of the marine food chain. Even though marine sea food is considered the main risk driver for MeHg exposure to people most research up to date has focused on Hg methylation processes in freshwater systems. This study identifies the mechanisms driving formation of MeHg during oxygen depletion in fjords, and shows how MeHg is made available in the surface water during oxygen intrusion. Studies of the biogeochemical structure in the water column of the Norwegian fjord Hunnbunn were performed in 2009, 2011 and 2012. In autumn of 2011 mixing flushing events were observed and lead to both positive and negative effects on the ecosystem state in the fjord. The oxygenated water intrusions lead to a decrease of the deep layer concentrations of hydrogen sulfide (H2S), ammonia and phosphate. On the other hand the intrusion also raised the H2S boundary from 8 m to a shallower depth of just 4 m. Following the intrusion was also observed an increase at shallower depths of nutrients combined with a decrease of pH. Before flushing events were observed concentrations of total Hg (TotHg) increased from 1.3 - 1.7 ng/L in the surface layer of the fjord to concentrations ranging from 5.2 ng/L to 6.4 ng/L in the anoxic zone. MeHg increased regularly from 0.04 ng/L in the surface water to a maximum concentration of 5.2 ng/L in the deeper layers. This corresponds to an amount of TotHg present as MeHg ranging from 2.1 % to 99 %. The higher concentrations of MeHg in the deeper layer corresponds to an area where no oxygen is present and concentrations of H2S exceeds 500 µM, suggesting a production of MeHg in the anoxic area as a result of sulphate reducing bacteria activity. After flushing the concentrations of TotHg showed a similar pattern ranging from 0.6 ng/L in the

  5. An immunofluorescence diagnostic test for feline viral rhinotracheitis.

    PubMed

    Carlson, J H; Scott, F W

    1978-03-01

    Hyperimmune serum against feline viral rhinotracheitis was produced in a goat and conjugated with a fluorescent dye. Cell cultures infected with rhinotracheitis virus had positive immunofluorescence. Cell cultures infected with other feline viruses and herpesviruses of other species did not fluoresce. In cats experimentally infected with rhinotracheitis virus, the virus was isolated from nasal and conjunctival swabs 1 to 9 days after inoculation. Nasal smears stained with the conjugated antiserum fluoresced 1 to 9 days after inoculation when clinical disease was most apparent. Conjunctival smears had positive immunofluorescence 1 to 6 days, but not 9 days, after inoculation. On postinoculation day 23, rhinotracheitis virus was not isolated from nasal or conjunctival swabs and nasal and conjunctival smears did not fluoresce. Rhinotracheitis virus or feline calicivirus was isolated from naturally infected cats with upper respiratory tract disease. Nasal and conjunctival smears from rhinotracheitis virus-infected cats had positive immunofluorescence in all cast showing clinical illness. Smears from 1 clinically normal cat from which rhinotracheitis virus was isolated did not fluoresce. Nasal and conjunctival smears from calicivirus-infected cats did not fluoresce. PMID:205147

  6. Analysis of Cardiomyocyte Development using Immunofluorescence in Embryonic Mouse Heart

    PubMed Central

    Wilsbacher, Lisa D.; Coughlin, Shaun R.

    2015-01-01

    During heart development, the generation of myocardial-specific structural and functional units including sarcomeres, contractile myofibrils, intercalated discs, and costameres requires the coordinated assembly of multiple components in time and space. Disruption in assembly of these components leads to developmental heart defects. Immunofluorescent staining techniques are used commonly in cultured cardiomyocytes to probe myofibril maturation, but this ex vivo approach is limited by the extent to which myocytes will fully differentiate in culture, lack of normal in vivo mechanical inputs, and absence of endocardial cues. Application of immunofluorescence techniques to the study of developing mouse heart is desirable but more technically challenging, and methods often lack sufficient sensitivity and resolution to visualize sarcomeres in the early stages of heart development. Here, we describe a robust and reproducible method to co-immunostain multiple proteins or to co-visualize a fluorescent protein with immunofluorescent staining in the embryonic mouse heart and use this method to analyze developing myofibrils, intercalated discs, and costameres. This method can be further applied to assess cardiomyocyte structural changes caused by mutations that lead to developmental heart defects. PMID:25866997

  7. Magneto immunofluorescence assay for diagnosis of celiac disease.

    PubMed

    Kergaravat, Silvina V; Beltramino, Luis; Garnero, Nidia; Trotta, Liliana; Wagener, Marta; Fabiano, Silvia N; Pividori, Maria Isabel; Hernandez, Silvia R

    2013-10-10

    A magneto immunofluorescence assay for the detection of anti-transglutaminase antibodies (ATG2) in celiac disease was developed. The ATG2 were recognized by transglutaminase enzyme immobilized on the magnetic beads and then the immunological reaction was revealed by antibodies labeled with peroxidase. The fluorescent response of the enzymatic reaction with o-phenylenediamine and H2O2 as substrates was correlated with anti-transglutaminase titer, showing EC50 and LOD values of 1:11,600 and 1:74,500 of antibody titers, respectively. A total number of 29 sera samples from clinically confirmed cases of celiac disease and 19 negative control samples were tested by the novel magneto immunofluorescence assay. The data were submitted to the receiver-operating characteristic plot (ROC) analysis which indicated that 8.1 U was the most effective cut-off value to discriminate correctly between celiac and non-celiac patients. The immunofluorescence assay exhibited a sensitivity of 96.6%, a specificity of 89.5% and an efficiency 93.8% compared with the commercial optical ELISA kit. PMID:24070488

  8. Research Techniques Made Simple: Immunofluorescence Antigen Mapping in Epidermolysis Bullosa.

    PubMed

    Has, Cristina; He, Yinghong

    2016-07-01

    Inherited epidermolysis bullosa is a group of genetic blistering diseases with a broad spectrum of clinical severity and molecular defects. Epidermolysis bullosa results from mutations in genes encoding proteins involved in cell-cell and cell-matrix adhesion in the epidermis. Immunofluorescence antigen mapping makes use of monoclonal antibodies against proteins of the dermal-epidermal junction zone to determine the layer of skin where cleavage occurs and the relative protein abundance. It allows the diagnosis of the type and subtype of inherited epidermolysis bullosa and sheds light on molecular mechanisms underlying the disease. Immunofluorescence mapping steps include obtaining a skin biopsy sample, processing the biopsy material, antigen-antibody interaction on tissue, washing, incubation with fluorescently conjugated secondary antibodies, mounting, observation under a fluorescence microscope, and interpretation. A minimal antibody panel allows discrimination of the main epidermolysis bullosa subtypes. Extended panels can be used depending on the diagnostic or scientific question to be addressed. Immunofluorescence mapping contributed to significant progress in understanding epidermolysis bullosa, including identification of new underlying genetic mutations, mutation mechanisms, and the presence of revertant mosaicism. It is also an important tool in the assessment of the efficacy of experimental therapeutic approaches. PMID:27342035

  9. Methylmercury-induced changes in gene transcription associated with neuroendocrine disruption in largemouth bass (Micropterus salmoides)

    USGS Publications Warehouse

    Richter, Catherine A.; Martyniuk, Christopher J.; Annis, Mandy L.; Brumbaugh, William G.; Chasar, Lia C.; Denslow, Nancy D.; Tillitt, Donald E.

    2014-01-01

    Methyl-mercury (MeHg) is a potent neuroendocrine disruptor that impairs reproductive processes in fish. The objectives of this study were to (1) characterize transcriptomic changes induced by MeHg exposure in the female largemouth bass (LMB) hypothalamus under controlled laboratory conditions, (2) investigate the health and reproductive impacts of MeHg exposure on male and female largemouth bass (LMB) in the natural environment, and (3) identify MeHg-associated gene expression patterns in whole brain of female LMB from MeHg-contaminated habitats. The laboratory experiment was a single injection of 2.5 μg MeHg/g body weight for 96 h exposure. The field survey compared river systems in Florida, USA with comparably lower concentrations of MeHg (Wekiva, Santa Fe, and St. Johns Rivers) in fish and one river system with LMB that contained elevated concentrations of MeHg (St. Marys River). Microarray analysis was used to quantify transcriptomic responses to MeHg exposure. Although fish at the high-MeHg site did not show overt health or reproductive impairment, there were MeHg-responsive genes and pathways identified in the laboratory study that were also altered in fish from the high-MeHg site relative to fish at the low-MeHg sites. Gene network analysis suggested that MeHg regulated the expression targets of neuropeptide receptor and steroid signaling, as well as structural components of the cell. Disease-associated gene networks related to MeHg exposure, based upon expression data, included cerebellum ataxia, movement disorders, and hypercalcemia. Gene responses in the CNS are consistent with the documented neurotoxicological and neuroendocrine disrupting effects of MeHg in vertebrates.

  10. Methylmercury teratogenesis in the killifish, Fundulus heteroclitus.

    PubMed

    Weis, P; Weis, J S

    1977-12-01

    Exposure of developing eggs of the killifish, Fundulus heteroclitus, to 0.03 or 0.04 mg/l of methylmercuric chloride resulted in a variety of abnormalities. Percentage of axis formation was reduced somewhat, and many embryos developed cyclopia or intermediate conditions leading to cyclopia, reflecting interference with induction of the forebrain. Defects in the cardiovascular system also appeared in the form of failure of the heart to differentiate properly into chambers. The heart was a thin, feebly beating tube, incapable of causing the blood to circulate. Other tissues, however, continued developing fairly normally, and embryos showed spontaneous movement comparable to controls. Embryos with severe cardiovascular or optic defects did not hatch. Upon hatching, some embryos which had previously appeared normal were found to have skeletal malformations in the form of vertebral bends or the inability to uncurl from the position which they had while still inside the chorion. Exposure to the toxicant for shorter periods of time (6, 12, or 24 hours) reduced the incidence of abnormalities. The second day of development was found to be the most sensitive period. PMID:413205

  11. Methylmercury Bioaccumulation in Rice and Wetland Biota: employing integrated indices of processes that drive methylmercury risk

    NASA Astrophysics Data System (ADS)

    Eagles-Smith, C.; Ackerman, J.; Windham-Myers, L.; Fleck, J.

    2013-12-01

    Wetlands often are associated with elevated methylmercury (MeHg) production and food web bioaccumulation, making them potentially important sources of Hg to surrounding waters and to wetland-dependent fish and wildlife. However, the cycling of MeHg through wetlands can vary markedly with wetland type. Agricultural wetlands such as rice fields can exhibit particularly pronounced MeHg concentrations and bioaccumulation because their biogeochemical, hydrological, and ecological characteristics facilitate the conversion of inorganic mercury (Hg) to MeHg. Rice fields are characterized by a series of seasonal extreme wetting and drying cycles, sulfate-containing fertilizers, and high levels of labile organic carbon, all of which are key processes in the Hg cycle. Rice fields comprise approximately 20% of freshwater habitats and 11% of cultivated land area globally, providing critical wildlife habitat while offering substantial economic, human health, and ecosystem benefits. Thus, there is strong impetus to better understand the drivers of Hg cycling in rice fields and to develop useful management approaches for minimizing Hg risk associated with rice agriculture without compromising rice production. We examined the role of rice wetlands on MeHg bioaccumulation through foodwebs by employing biosentinel caged fish as integrators of MeHg cycling processes. With experimental field studies in California's Central Valley, we placed biosentinel fishes into nine rice wetlands that were subjected to three different harvest strategies, and into nine managed wetlands that encompassed three different hydrological regimes. We simultaneously measured a suite of biogeochemical processes in surface water, sediment, and pore water in order to link the response in fish Hg bioaccumulation with within-field processes that regulate MeHg cycling. Our preliminary results indicate that fish Hg concentrations were 1.6 times higher in rice wetlands than in managed wetlands. Additionally, fish Hg

  12. Photodemethylation of Methylmercury in Eastern Canadian Arctic Thaw Pond and Lake Ecosystems.

    PubMed

    Girard, Catherine; Leclerc, Maxime; Amyot, Marc

    2016-04-01

    Permafrost thaw ponds of the warming Eastern Canadian Arctic are major landscape constituents and often display high levels of methylmercury (MeHg). We examined photodegradation potentials in high-dissolved organic matter (DOC) thaw ponds on Bylot Island (BYL) and a low-DOC oligotrophic lake on Cornwallis Island (Char Lake). In BYL, the ambient MeHg photodemethylation (PD) rate over 48 h of solar exposure was 6.1 × 10(-3) m(2) E(-1), and the rate in MeHg amended samples was 9.3 × 10(-3) m(2) E(-1). In contrast, in low-DOC Char Lake, PD was only observed in the first 12 h, which suggests that PD may not be an important loss process in polar desert lakes. Thioglycolic acid addition slowed PD, while glutathione and chlorides did not impact northern PD rates. During an ecosystem-wide experiment conducted in a covered BYL pond, there was neither net MeHg increase in the dark nor loss attributable to PD following re-exposure to sunlight. We propose that high-DOC Arctic thaw ponds are more prone to MeHg PD than nearby oligotrophic lakes, likely through photoproduction of reactive species rather than via thiol complexation. However, at the ecosystem level, these ponds, which are widespread through the Arctic, remain likely sources of MeHg for neighboring systems. PMID:26938195

  13. Brain lesions in mallard ducklings from parents fed methylmercury

    USGS Publications Warehouse

    Heinz, G.H.; Locke, L.N.

    1976-01-01

    Methylmercury dicyandiamide was fed to mallard ducks at 3 ppm mercury. Mercury accumulated in the eggs to an average of 7.18 and 5.46 ppm on a wet-weight basis in 2 successive years. Mercury in the eggs is believed to have caused brain lesions in the hatched ducklings. Lesions included demyelination, neuron shrink-age, necrosis, and hemorrhage in the meninges overlying the cerebellum. Brains of dead ducklings contained an average of 6.17 and 5.19 ppm mercury on a wet-weight basis in 2 successive years.

  14. [Microcosm Simulation Study and Methylmercury Forming Mechanism at Landscape Water of City].

    PubMed

    Liu, Xiao-hong; Si, You-bin; Guo, Zi-wei; Du, Cheng-zhu; Zhu, Cong-cong

    2016-04-15

    Mercury is harmful to the environment, which has gradually become one of the research hotspots. Sediments, as a main repository of pollutants, have an important impact on water quality and the internal organisms, which deserves our research. In this paper, we focused on Hefei landscape water sediment and tried to investigate the status of inorganic mercury and methylmercury pollutions in the sediment. To study the conversion process from inorganic mercury to methylmercury and their enrichment levels and mechanism, we established the ecological chain of "sediment-water-grass-fish" through analog microcosm examination. The results were as follows: from ten water and sediment samples in Hefei landscape water sediment, we found that the contents of inorganic mercury and methylmercury ranged 11.74-13.12 µg · kg⁻¹ and 0.37-2.23 µg · kg⁻¹, respectively. The microcosm examination showed that: with increasing culture time, inorganic mercury in sediments gradually decreased. There was a phenomenon that the content of methylmercury increased at first and then decreased to reach the balance later. Both the inorganic mercury and methylmercury in water change showed an increasing trend. The enrichment contents of inorganic mercury in Egeria densa Planch, and golden mandarin fish (Siniperca scherzeri Steindachner) were low while their enrichment of methylmercury could he great. In addition, we found that both the bioaccumulation ability and the enrichment coefficient of methylmercury in the body of golden mandarin fish were the maximum during the same period. PMID:27548953

  15. Methylmercury determination in biological samples using electrothermal atomic absorption spectrometry after acid leaching extraction.

    PubMed

    Saber-Tehrani, Mohammad; Hashemi-Moghaddam, Hamid; Givianrad, Mohammad Hadi; Abroomand-Azar, Parviz

    2006-11-01

    An efficient and sensitive method for the determination of methylmercury in biological samples was developed based on acid leaching extraction of methylmercury into toluene. Methylmercury in the organic phase was determined by electrothermal atomic absorption spectrometry (ETAAS). The methylmercury signal was enhanced and the reproducibility increased by formation of certain complexes and addition of Pd-DDC modifier. The complex of methylmercury with DDC produced the optimum analytical signal in terms of sensitivity and reproducibility compared to complexes with dithizone, cysteine, 1,10-phenanthroline, and diethyldithiocarbamate. Method performance was optimized by modifying parameters such as temperature of mineralization, atomization, and gas flow rate. The limit of detection for methylmercury determination was 0.015 mug g(-1) and the RSD of the whole procedure was 12% for human teeth samples (n=5) and 15.8% for hair samples (n=5). The method's accuracy was investigated by using NIES-13 and by spiking the samples with different amounts of methylmercury. The results were in good agreement with the certified values and the recoveries were 88-95%. PMID:16896613

  16. Inhibition of the thioredoxin system in the brain and liver of zebra-seabreams exposed to waterborne methylmercury

    SciTech Connect

    Branco, Vasco; Canario, Joao; Holmgren, Arne; Carvalho, Cristina

    2011-03-01

    Mercury compounds were recently found to interact in vitro with the thioredoxin system, inhibiting both Thioredoxin (Trx) and Thioredoxin reductase (TrxR). In order to evaluate if Trx and TrxR are affected in vivo by methylmercury (MeHg), we exposed juvenile zebra-seabreams to different concentrations of this toxicant in water for 28 days followed by a 14-day depuration period. Methylmercury accumulated to a larger extent in the kidney and liver of fishes, but decreased significantly during the depuration. During the exposure, MeHg percentage in the liver reached levels above 90% of total mercury (HgT) decreasing to 60% of HgT by the end of the depuration period. In the kidney, MeHg accounted for 50-70% of HgT. In the brain and muscle, mercury accumulated throughout the exposure with all mercury being MeHg. The total mercury kept increasing in these organs during the depuration period. However, in the brain, this increase in HgT was accompanied by a decrease in the MeHg percentage ({approx} 10%). In the liver, both Trx and TrxR activities were significantly reduced (TrxR - 40%; Trx - 70%) by the end of the exposure, but recovered to control levels (100%) during the depuration. In the brain, both enzymes where inhibited during the depuration period (TrxR - 75%; Trx - 70%) when some production of inorganic mercury was detected. Activity of glutathione reductase showed increased levels when TrxR activity was low, suggesting complementarity between both systems. These results indicate that in vivo the thioredoxin system is a toxicological target for MeHg with TrxR being particularly affected.

  17. Methylmercury is the predominant form of mercury in bird eggs: a synthesis

    USGS Publications Warehouse

    Ackerman, Joshua T.; Herzog, Mark P.; Schwarzbach, Steven E.

    2013-01-01

    Bird eggs are commonly used in mercury monitoring programs to assess methylmercury contamination and toxicity to birds. However, only 6% of >200 studies investigating mercury in bird eggs have actually measured methylmercury concentrations in eggs. Instead, studies typically measure total mercury in eggs (both organic and inorganic forms of mercury), with the explicit assumption that total mercury concentrations in eggs are a reliable proxy for methylmercury concentrations in eggs. This assumption is rarely tested, but has important implications for assessing risk of mercury to birds. We conducted a detailed assessment of this assumption by (1) collecting original data to examine the relationship between total and methylmercury in eggs of two species, and (2) reviewing the published literature on mercury concentrations in bird eggs to examine whether the percentage of total mercury in the methylmercury form differed among species. Within American avocets (Recurvirostra americana) and Forster’s terns (Sterna forsteri), methylmercury concentrations were highly correlated (R2 = 0.99) with total mercury concentrations in individual eggs (range: 0.03–7.33 μg/g fww), and the regression slope (log scale) was not different from one (m = 0.992). The mean percentage of total mercury in the methylmercury form in eggs was 97% for American avocets (n = 30 eggs), 96% for Forster’s terns (n = 30 eggs), and 96% among all 22 species of birds (n = 30 estimates of species means). The percentage of total mercury in the methylmercury form ranged from 63% to 116% among individual eggs and 82% to 111% among species means, but this variation was not related to total mercury concentrations in eggs, foraging guild, nor to a species life history strategy as characterized along the precocial to altricial spectrum. Our results support the use of total mercury concentrations to estimate methylmercury concentrations in bird eggs.

  18. Methylmercury is the predominant form of mercury in bird eggs: a synthesis.

    PubMed

    Ackerman, Joshua T; Herzog, Mark P; Schwarzbach, Steven E

    2013-02-19

    Bird eggs are commonly used in mercury monitoring programs to assess methylmercury contamination and toxicity to birds. However, only 6% of >200 studies investigating mercury in bird eggs have actually measured methylmercury concentrations in eggs. Instead, studies typically measure total mercury in eggs (both organic and inorganic forms of mercury), with the explicit assumption that total mercury concentrations in eggs are a reliable proxy for methylmercury concentrations in eggs. This assumption is rarely tested, but has important implications for assessing risk of mercury to birds. We conducted a detailed assessment of this assumption by (1) collecting original data to examine the relationship between total and methylmercury in eggs of two species, and (2) reviewing the published literature on mercury concentrations in bird eggs to examine whether the percentage of total mercury in the methylmercury form differed among species. Within American avocets (Recurvirostra americana) and Forster's terns (Sterna forsteri), methylmercury concentrations were highly correlated (R(2) = 0.99) with total mercury concentrations in individual eggs (range: 0.03-7.33 μg/g fww), and the regression slope (log scale) was not different from one (m = 0.992). The mean percentage of total mercury in the methylmercury form in eggs was 97% for American avocets (n = 30 eggs), 96% for Forster's terns (n = 30 eggs), and 96% among all 22 species of birds (n = 30 estimates of species means). The percentage of total mercury in the methylmercury form ranged from 63% to 116% among individual eggs and 82% to 111% among species means, but this variation was not related to total mercury concentrations in eggs, foraging guild, nor to a species life history strategy as characterized along the precocial to altricial spectrum. Our results support the use of total mercury concentrations to estimate methylmercury concentrations in bird eggs. PMID:23331121

  19. Effects of methylmercury on epigenetic markers in three model species: mink, chicken and yellow perch

    PubMed Central

    Basu, Niladri; Head, Jessica; Nam, Dong-Ha; Pilsner, J. Richard; Carvan, Michael J; Chan, Hing Man; Goetz, Frederick W; Murphy, Cheryl A; Rouvinen-Watt, Kirsti; Scheuhammer, Anton M

    2015-01-01

    We previously reported that methylmercury (MeHg) exposure is associated with DNA hypomethylation in the brain stem of male polar bears. Here, we conveniently use archived tissues obtained from controlled laboratory exposure studies to look for evidence that MeHg can disrupt DNA methylation across taxa. Brain (cerebrum) tissues from MeHg-exposed mink (Neovison vison), chicken (Gallus gallus) and yellow perch (Perca flavescens) were analyzed for total Hg levels and global DNA methylation. Tissues from chicken and mink, but not perch, were also analyzed for DNA methyltransferase (DNMT) activity. In mink we observed significant reductions in global DNA methylation in an environmentally-relevant dietary exposure group (1ppm MeHg), but not in a higher group (2ppm MeHg). DNMT activity was significantly reduced in all treatment groups. In chicken or yellow perch, no statistically significant effects of MeHg were observed. Dose-dependent trends were observed in the chicken data but the direction of the change was not consistent between the two endpoints. Our results suggest that MeHg can be epigenetically active in that it has the capacity to affect DNA methylation in mammals. The variability in results across species may suggest inter-taxa differences in epigenetic responses to MeHg, or may be related to differences among the exposure scenarios used as animals were exposed to MeHg through different routes (dietary, egg injection), for different periods of time (19 – 89 days) and at different life stages (embryonic, juvenile, adult). PMID:23481557

  20. Differences in mortality among bobwhite fed methylmercury chloride dissolved in various carriers

    USGS Publications Warehouse

    Spann, J.W.; Heinz, G.H.; Camardese, M.B.; Hill, E.F.; Moore, J.F.; Murray, H.C.

    1986-01-01

    Twelve-day-old bobwhite chicks were fed a diet containing 0, 5.4 or 20 ppm methylmercury chloride. The methylmercury chloride was added to the diet either in a dry, pulverized form or dissolved in acetone, propylene glycol or corn oil. Mortality was measured for 6 weeks, and samples of liver were saved for mercury analysis. Mortality was significantly lower in birds fed 20 ppm methylmercury chloride when acetone was the solvent. The reduced mortality could not be explained by effects of acetone on dietary level of mercury or on uptake of mercury into the body.

  1. Dissolved organic matter reduces algal accumulation of methylmercury

    USGS Publications Warehouse

    Luengen, Allison C.; Fisher, Nicholas S.; Bergamaschi, Brian A.

    2012-01-01

    Dissolved organic matter (DOM) significantly decreased accumulation of methylmercury (MeHg) by the diatom Cyclotella meneghiniana in laboratory experiments. Live diatom cells accumulated two to four times more MeHg than dead cells, indicating that accumulation may be partially an energy-requiring process. Methylmercury enrichment in diatoms relative to ambient water was measured by a volume concentration factor (VCF). Without added DOM, the maximum VCF was 32 x 104, and the average VCF (from 10 to 72 h) over all experiments was 12.6 x 104. At very low (1.5 mg/L) added DOM, VCFs dropped by approximately half. At very high (20 mg/L) added DOM, VCFs dropped 10-fold. Presumably, MeHg was bound to a variety of reduced sulfur sites on the DOM, making it unavailable for uptake. Diatoms accumulated significantly more MeHg when exposed to transphilic DOM extracts than hydrophobic ones. However, algal lysate, a labile type of DOM created by resuspending a marine diatom in freshwater, behaved similarly to a refractory DOM isolate from San Francisco Bay. Addition of 67 μM L-cysteine resulted in the largest drop in VCFs, to 0.28 x 104. Although the DOM composition influenced the availability of MeHg to some extent, total DOM concentration was the most important factor in determining algal bioaccumulation of MeHg.

  2. Role of Protein A in Nonspecific Immunofluorescence of Staphylococcus aureus

    PubMed Central

    Forsgren, Arne; Forsum, Urban

    1970-01-01

    γG-globulin from nonimmunized rabbits and from rabbits immunized with various bacteria reacted in the immunofluorescence technique with protein A-containing Staphylococcus aureus. Pepsin digestion of most immunoglobulin preparations eliminated the reaction, thus showing that the Fc fragment is involved and that the reaction is not a true antigen-antibody reaction. As the specific immunological activity of the immunoglobulin molecules was intact after digestion, it is suggested that the method be used to eliminate reactions with S. aureus in the fluorescent-antibody technique. PMID:16557850

  3. The protein transportation pathway from Golgi to vacuoles via endosomes plays a role in enhancement of methylmercury toxicity

    NASA Astrophysics Data System (ADS)

    Hwang, Gi-Wook; Murai, Yasutaka; Takahashi, Tsutomu; Naganuma, Akira

    2014-07-01

    Methylmercury causes serious damage to the central nervous system, but the molecular mechanisms of methylmercury toxicity are only marginally understood. In this study, we used a gene-deletion mutant library of budding yeast to conduct genome-wide screening for gene knockouts affecting the sensitivity of methylmercury toxicity. We successfully identified 31 genes whose deletions confer resistance to methylmercury in yeast, and 18 genes whose deletions confer hypersensitivity to methylmercury. Yeast genes whose deletions conferred resistance to methylmercury included many gene encoding factors involved in protein transport to vacuoles. Detailed examination of the relationship between the factors involved in this transport system and methylmercury toxicity revealed that mutants with loss of the factors involved in the transportation pathway from the trans-Golgi network (TGN) to the endosome, protein uptake into the endosome, and endosome-vacuole fusion showed higher methylmercury resistance than did wild-type yeast. The results of our genetic engineering study suggest that this vesicle transport system (proteins moving from the TGN to vacuole via endosome) is responsible for enhancing methylmercury toxicity due to the interrelationship between the pathways. There is a possibility that there may be proteins in the cell that enhance methylmercury toxicity through the protein transport system.

  4. Studies of micronuclei and other nuclear abnormalities in red blood cells of Colossoma macropomum exposed to methylmercury

    PubMed Central

    da Rocha, Carlos Alberto Machado; da Cunha, Lorena Araújo; da Silva Pinheiro, Raul Henrique; de Oliveira Bahia, Marcelo; Burbano, Rommel Mario Rodríguez

    2011-01-01

    The frequencies of micronuclei (MN) and morphological nuclear abnormalities (NA) in erythrocytes in the peripheral blood of tambaqui (Colossoma macropomum), treated with 2 mg.L−1 methylmercury (MeHg), were analyzed. Two groups (nine specimens in each) were exposed to MeHg for different periods (group A - 24 h; group B - 120 h). A third group served as negative control (group C, untreated; n = 9). Although, when compared to the control group there were no significant differences in MN frequency in the treated groups, for NA, the differences between the frequencies of group B (treated for 120 h) and the control group were extremely significant (p < 0.02), thus demonstrating the potentially adverse effects of MeHg on C. macropomum erythrocytes after prolonged exposure. PMID:22215976

  5. Performance Evaluation of an Improved GC-MS Method to Quantify Methylmercury in Fish.

    PubMed

    Watanabe, Takahiro; Kikuchi, Hiroyuki; Matsuda, Rieko; Hayashi, Tomoko; Akaki, Koichi; Teshima, Reiko

    2015-01-01

    Here, we set out to improve our previously developed methylmercury analytical method, involving phenyl derivatization and gas chromatography-mass spectrometry (GC-MS). In the improved method, phenylation of methylmercury with sodium tetraphenylborate was carried out in a toluene/water two-phase system, instead of in water alone. The modification enabled derivatization at optimum pH, and the formation of by-products was dramatically reduced. In addition, adsorption of methyl phenyl mercury in the GC system was suppressed by co-injection of PEG200, enabling continuous analysis without loss of sensitivity. The performance of the improved analytical method was independently evaluated by three analysts using certified reference materials and methylmercury-spiked fresh fish samples. The present analytical method was validated as suitable for determination of compliance with the provisional regulation value for methylmercury in fish, set in the Food Sanitation haw. PMID:26156161

  6. A systems approach to risk assessment: Application to methylmercury from coal combustion

    SciTech Connect

    Saroff, L.; Lipfert, F.W.; Moskowitz, P.D.

    1995-01-01

    The Department of Energy (DOE) asked Brookhaven National Laboratory (BNL) to perform a probabilistic assessment of the health risks associated with Hg from coal-fired power plants. The objective of the assessment is to estimate the incremental health risks that might ensue from a typical coal-fired power plant, together with their uncertainties, taking into account existing background levels and the actual adverse health effects that have previously been associated with exposure to various Hg species. Mercury has a long history of association with adverse neurological effects at high exposure levels. The most important current exposure pathway has been found to be ingestion of fish containing methylmercury (MeHg), which is the end product of bioconcentration moving up the aquatic food chain. Mercury can enter natural waters from either industrial discharges or from atmospheric deposition of various inorganic Ho. compounds. Because of the worldwide background and the existence of local emissions sources, Hg deposition must be considered on local, regional and global scales. The regulatory technical challenge presented by methy1mercury is to protect public health without foreclosing an appreciable a portion of the food supply or impacting on the lifestyles of North American native populations. This paper presents an abbreviated account of the DOE/BNL risk assessment, as viewed from a systems perspective. We review the structure of the model, the sources of data used, the assumptions that were made, and the interpretation of the findings. Since publication of the first risk assessment report, we have refined our estimates of local atmospheric dispersion and deposition and {open_quotes}calibrated{close_quotes} the pharmacokinetic portion of the model against observations.

  7. Methylmercury and trace elements in the marine fish from coasts of East China.

    PubMed

    Xia, Chonghuan; Wu, Xiaoguo; Lam, James C W; Xie, Zhouqing; Lam, Paul K S

    2013-01-01

    Fish consumption is an important source of human exposure to heavy metals. To determine the health risks for metals by consumption of marine fish in China, three species of fish, namely large yellow croaker (Pseudosciaena crocea), small yellow croaker (Pseudosciaena polyactis) and silver pomfret (Pampus argenteus) were collected and analyzed for methylmercury (MeHg), total mercury (T-Hg), selenium, cadmium, cobalt, chromium, copper, iron, manganese, nickel, lead, strontium and zinc. The large yellow croakers had the highest concentrations of mercury, lead, nickel and zinc, and the levels of MeHg were positively correlated to T-Hg. The ratios of MeHg to T-Hg in yellow croakers were significantly higher than those in silver pomfret, indicating differences in accumulation and magnification of MeHg in these two types of fish. The concentration of T-Hg was found to decrease as the Se level in fish tissues increased. Cadmium levels in 16% of the samples were higher than the criterion recommended by the European Commission Regulation. The concentrations of other metals were well below international standards. A human health risk assessment showed that the estimated daily intake of these metals did not exceed the reference dose established by the US Environmental Protection Agency. The hazard quotients (HQs) were all less than 1, indicating a situation of no risk for consumption of these fish. PMID:23802158

  8. Hepatic enzyme activity after combined administration of methylmercury, lead and cadmium in the pekin duck

    SciTech Connect

    Jordan, S.A.; Bhatnagar, M.K. )

    1990-04-01

    In order to assess adequately the environmental impact of heavy metals it is important to consider that they may occur simultaneously in the environment, where they may interact to alter their individual toxicities on living systems. Metals such as mercury (Hg), lead (Pb) and cadmium (Cd) can be found in all levels of the polluted ecosystem, and in animals inhabiting such areas. In the polluted aquatic environment waterfowl have been noted to accumulate high levels of these metals in their tissues. A major toxic manifestation of heavy metal exposure is the perturbation of a wide range of enzyme systems in virtually all subcellular compartments. With the exception of lead, little data is available on the effects of metals on avian enzyme systems. The present report describes the effects observed in vivo on acid phosphatase (AP), glutathione S-transferase (GST) and cytochrome c oxidase (cyt c ox) in the liver of pekin ducks exposed to combinations of methylmercury (MeHg), lead and cadmium.

  9. Pharmacokinetics and distribution of dietary tributyltin and methylmercury in the snow crab (Chionoecetes opilio)

    SciTech Connect

    Rouleau, C.; Gobeil, C.; Tjaelve, H.

    1999-10-01

    The pharmacokinetics and distribution of a single 5-{micro}g dietary dose of radiolabeled [{sup 113}Sn]tributyltin (TBT) and [{sup 203}Hg]methylmercury (MeHg) were studied over 154 days in the snow crab, using in vivo gamma counting and whole-body autoradiography. Experiment was done under conditions typical of those encountered in the cold natural habitat of this crustacean. Retention efficiency was high for both compounds, and two kinetic pools could be distinguished. Elimination of the first pool proceeded within 20--80 days, but it accounted for 27--62% of the assimilated TBT, compared to 8--11% for MeHg. Biological half-life of the second pool was 33--187 days for TBT and 520--650 days for MeHg. Autoradiographic and dissection data revealed a less homogeneous distribution of the radiolabel and much higher radioactivity in gut lumen for TBT compared to MeHg. This suggests that the larger size of the first pool in the case of TBT resulted from metabolization in the hepatopancreas and fecal elimination of the metabolites. The whole-body biomagnification factor (BMF) that would result from the long-term chronic exposure of snow crab to TBT-contaminated food was estimated as 0.1--0.6. Although these BMF values were an order of magnitude lower than those estimated for MeHg, they are not negligible and indicate that uptake of TBT via food may be an important accumulation route.

  10. Maternal transfer of inorganic mercury and methylmercury in aquatic and terrestrial arthropods.

    PubMed

    Saxton, Heidi J; Goodman, James R; Collins, Jeffrey N; Black, Frank J

    2013-11-01

    The transfer of mercury from females to their offspring plays an important role in mercury accumulation and toxicity during early development. To quantify the transfer of inorganic mercury and methylmercury from female arthropods to their eggs, the authors collected and analyzed brine shrimp (Artemia franciscana), wolf spiders (Alopecosa spp.), and their attached eggs from aquatic and terrestrial ecosystems at the Great Salt Lake, Utah, USA. Essentially all of the mercury in both the female brine shrimp and their eggs was methylmercury (94 ± 17% and 90 ± 21%, respectively). The brine shrimp eggs had methylmercury concentrations that were 84 ± 2% lower than in the females, reflecting the fact that females transferred 45 ± 4% of their total body mass but only 11 ± 3% of their methylmercury burden to their eggs. As a result of this sequestration, the concentration of methylmercury in the female brine shrimp increased by 62 ± 8% during egg formation. The percentage of the total mercury that was methylmercury in female wolf spiders (77 ± 21%) was similar to that in their egg masses (81 ± 19%), indicating similar maternal transfer efficiencies for inorganic mercury and methylmercury in these invertebrates. The concentration of inorganic mercury and methylmercury in the female spiders was the same as in their eggs. These arachnids transferred 48 ± 9% of their total body mass, 55 ± 13% of their inorganic mercury, and 50 ± 9% of their methylmercury to their egg masses. Thus, female wolf spiders do not have the ability to reduce the transfer of methylmercury to their eggs, nor does this process represent an important pathway for the depuration of mercury. The present study demonstrates that although some arthropods have mechanisms to minimize the transfer of methylmercury to their eggs and reduce the potential for mercury toxicity during early development, other arthropods do not. PMID:23939924

  11. Effect of Lycium bararum polysaccharides on methylmercury-induced abnormal differentiation of hippocampal stem cells

    PubMed Central

    Tian, Jian-Ying; Chen, Wei-Wei; Cui, Jing; Wang, Hao; Chao, Ci; Lu, Zhi-Yan; Bi, Yong-Yi

    2016-01-01

    The aim of the present study was to observe the effects of a general extract of Lycium bararum polysaccharides (LBPs) on methylmercury (MeHg)-induced damage in hippocampus neural stem cells (hNSCs). The hippocampal tissues of embryonic day 16 Sprague-Dawley rats were extracted for the isolation, purification and cloning of hNSCs. Following passage and proliferation for 10 days, the cells were allocated at random into the following groups: Control, LBPs, MeHg and MeHg + LBPs. MTT and microtubule-associated protein 2 (MAP-2)/glial fibrillary acidic protein/Hoechst immunofluorescence tests were performed to detect the differentiation and growth of hNSCs in the various groups. The differentiation rate of MeHg-treated hNSCs and the perimeter of MAP-2-positive neurons were 3.632±0.63% and 62.36±5.58 µm, respectively, significantly lower compared with the control group values of 6.500±0.81% and 166±8.16 µm (P<0.05). Furthermore, the differentiation rate and the perimeter of MAP-2-positive neurons in LBPs groups cells was 7.75±0.59% and 253.3±11.21 µm, respectively, significantly higher compared with the control group (P<0.05). The same parameters in the MeHg + LBPs group were 5.92±0.98% and 111.9±6.07 µm, respectively, significantly higher than the MeHg group (P<0.05). The astrocyte differentiation rates in the MeHg and MeHg + LBPs group were 41.19±2.14 and 34.58±1.70, respectively (P<0.05). These results suggest that LBPs may promote the generation and development of new neurons and inhibit the MeHg-induced abnormal differentiation of astrocytes. Thus, LBPs may be considered to be a potential new treatment for MeHg-induced neurotoxicity in hNSCs. PMID:27446261

  12. Why dissolved organic matter (DOM) enhances photodegradation of methylmercury

    SciTech Connect

    Qian, Yun; Yin, Xiangping Lisa; Brooks, Scott C; Liang, Liyuan; Gu, Baohua

    2014-01-01

    Methylmercury (MeHg) is known to degrade photochemically, but it remains unclear what roles naturally dissolved organic matter (DOM) and complexing organic ligands play in MeHg photodegradation. Here we investigate the rates and mechanisms of MeHg photodegradation using DOM samples with varying oxidation states and origins as well as organic ligands with known molecular structures. All DOM and organic ligands increased MeHg photodegradation under solar irradiation, but the first-order rate constants varied depending on the oxidation state of DOM and the type and concentration of the ligands. Compounds containing both thiols and aromatics (e.g., thiosalicylate and reduced DOM) increased MeHg degradation rates far greater than those containing only aromatic or thiol functional groups (e.g., salicylate or glutathione). Our results suggest that, among other factors, the synergistic effects of thiolate and aromatic moieties in DOM greatly enhance MeHg photodegradation.

  13. Variability of neuropathologic lesions in experimental methylmercurial encephalopathy in primates.

    PubMed Central

    Shaw, C. M.; Mottet, N. K.; Body, R. L.; Luschei, E. S.

    1975-01-01

    Acute and chronic intoxications of rhesus monkeys with methylmercury produced lesions in the central nervous system (CNS) with different distributions. Neuronal degeneration and astroglial proliferation predominated in the dentate nucleus, lateral geniculate nucleus, thalamus and pontine nuclei in 2 monkeys that received 2 mg/kg/day for 17 and 18 days, whereas pseudolaminar necrosis and astroglial proliferation were observed in the cerebral crotex, maximally in the calcarine and insular regions, in 4 monkeys that received 0.5 to 0.8 mg/kg/day for 3 to 8.5 months. Mercury concentrations in the CNS were much higher in the acutely intoxicated animals than in the chronically intoxicated animals, but the correlation between concentrations of mercury and the histologic destruction was not precise. Images Figure 5 Figure 6 Figure 7 Figure 8 Figure 9 Figure 1 Figure 2 Figure 3 Figure 4 PMID:821350

  14. Adaptive automatic segmentation of Leishmaniasis parasite in Indirect Immunofluorescence images.

    PubMed

    Ouertani, F; Amiri, H; Bettaib, J; Yazidi, R; Ben Salah, A

    2014-01-01

    This paper describes the first steps for the automation of the serum titration process. In fact, this process requires an Indirect Immunofluorescence (IIF) diagnosis automation. We deal with the initial phase that represents the fluorescence images segmentation. Our approach consists of three principle stages: (1) a color based segmentation which aims at extracting the fluorescent foreground based on k-means clustering, (2) the segmentation of the fluorescent clustered image, and (3) a region-based feature segmentation, intended to remove the fluorescent noisy regions and to locate fluorescent parasites. We evaluated the proposed method on 40 IIF images. Experimental results show that such a method provides reliable and robust automatic segmentation of fluorescent Promastigote parasite. PMID:25571049

  15. Chemical Pretreatment of Growth Plate Cartilage Increases Immunofluorescence Sensitivity

    PubMed Central

    Ahrens, Molly J.; Dudley, Andrew T.

    2011-01-01

    Immunofluorescence detection of proteins in growth plate cartilage is often unsuccessful because of innate autofluorescence, fixative-induced fluorescence, and dense cartilage matrix, which can inhibit antibody penetration. To overcome these limitations, the authors have tested various chemical pretreatments, including the autofluorescence quencher sodium borohydride, the antigen retrieval method of boiling sodium citrate, sugar-degrading enzymes (hyaluronidase, heparinase, and chondroitinase), and the proteolytic enzyme protease XXIV. Here the authors show that, in most cases, background fluorescence in cartilage is the primary obstacle to high-quality imaging. Blocking intrinsic fluorescence of the specimen in combination with specific pretreatments allows visualization using antibodies that previously did not generate a robust signal in the growth plate. Each antibody requires a specific combination of chemical pretreatments that must be empirically determined to achieve optimal staining levels. This manuscript contains online supplemental material at http://www.jhc.org. Please visit this article online to view these materials. PMID:21411811

  16. Immunofluorescence studies of disseminated Hantaan virus infection of suckling mice.

    PubMed Central

    Kurata, T; Tsai, T F; Bauer, S P; McCormick, J B

    1983-01-01

    Hantaan virus, the etiological agent of Korean hemorrhagic fever, was inoculated intracerebrally or intraperitoneally into suckling mice, and the course of the infection was followed by infectivity titration and immunofluorescence studies. Mice became ill and were moribund by 13 to 14 days postinfection. In mice inoculated either intracerebrally or intraperitoneally, virus antigen was present in brain, heart, lungs, liver, and kidney. Less consistently, specific fluorescence was observed in spleen, pituitary gland, thymus, lymph nodes, adrenal, pancreas, salivary glands, trigeminal ganglia, adipose tissue, intestine, and muscle. In all of these tissues, the primary target of infection was the capillary endothelium. In mice inoculated intracerebrally, virus antigen was present mainly in choroid plexus, hippocampal nuclei, and meninges, but in mice inoculated intraperitoneally, central nervous system infection was marked by antigen accumulation in cortical nuclei and thalamus. Images PMID:6134678

  17. Direct immunofluorescence on hair follicles--present and future perspectives.

    PubMed

    Alexandru, Adina; Zurac, Sabina; Salavastru, Carmen M; Andrei, Razvan; Tebeica, Tiberiu; Staniceanu, Florica; Tiplica, George S

    2013-06-01

    Direct immunofluorescence (DIF) is an important tool for evaluating bullous autoimmune and connective tissue disorders. We report 21 cases of pemphigus vulgaris, bullous pemphigoid and lupus erythematosus that were investigated by performing DIF on scalp hair follicles. The study was done using a simplified technique of preparing the hairs for DIF testing. The anagen hairs tested positive in pemphigus vulgaris patients while the telogen hairs were negative. In bullous pemphigoid and lupus erythematosus cases hair DIF presented negative results.Hair DIF has the potential of taking the place of skin or mucosal DIF in pemphigus patients if performed on anagen hair follicles. The technique used to perform hair DIF is important in obtaining reliable results and eliminating the possibility of generating false-negative testing. Larger studies are needed in order to validate this method. PMID:23689693

  18. Immunofluorescence versus ELISA for the detection of antinuclear antigens.

    PubMed

    Rondeel, Jan M M

    2002-05-01

    Determining the presence and specificity of antinuclear antigens (ANA) is a challenge to a laboratory involved in the diagnosis of connective tissue disease (CTD). The immunofluorescent technique (IF), once considered the gold standard, is more and more displaced by ELISA. ELISA can be fully automated and the interpretation does not require the extensive experience needed in IF. However, literature in which both techniques are compared does not give unequivocal conclusions that ELISA indeed performs better. The clue as to which technique is best in the cascade testing of ANA, is given by its clinical value, not only by its technical and logistic performance. Selective test ordering is strongly recommended to increase the predictive value of these tests. The pros and cons of both techniques are discussed. PMID:12050861

  19. Dermoscopy and direct immunofluorescence findings of elastosis perforans serpiginosa.

    PubMed

    Ramírez-Bellver, J L; Bernárdez, C; Macías, E; Moya, L; Molina-Ruiz, A M; Cannata Ortiz, P; Requena, L

    2016-08-01

    Elastosis perforans serpiginosa (EPS) is a rare skin disorder characterized by transepidermal elimination of abnormal elastic fibres. We present a new case of D-penicillamine (DPA)-induced EPS, and describe the clinical, dermoscopic, histopathological and direct immunofluorescence (DIF) findings. A 33-year-old woman receiving treatment with DPA presented with annular skin lesions. Digital dermoscopy of the lesions showed a central area of pink and yellowish discolouration with keratotic papules in the periphery, surrounded by a white halo, disposed in a way that resembled the islands of an archipelago. Other lesions showed a white to yellow central colouration and 'chrysalides' surrounding the keratotic plugs. Linear and granular deposits of IgG attached to the abnormal elastic fibres were seen with DIF. Dermoscopy can be helpful in the diagnosis of EPS. Moreover, DIF findings in skin biopsies of this case support the immune-mediated pathogenesis of EPS. PMID:27378586

  20. Clinical Application of Immunofluorescence I. Grouping β-Hemolytic Streptococci

    PubMed Central

    Smith, Thomas B.

    1965-01-01

    Smith, Thomas B. (Armed Forces Institute of Pathology, Washington, D.C.). Clinical application of immunofluorescence. I. Grouping β-hemolytic streptococci. J. Bacteriol. 89:198–204. 1965.—Procedures are described for the production of antistreptococcal serum in rabbits and for the preparation of group-specific conjugates for Lancefield groups A, C, and G. A modification of the conventional technique of absorption and inhibition to prevent cross-reactions with common antigens was used with excellent results. In addition, a promising new approach to eliminating cross-reactions of group A conjugate with antigens of groups C and G by dilution with group A-variant antiserum was tested. A complete method is introduced that enables the clinical laboratory to report whether group A streptococci are present in a given throat culture well within 24 hr after the physician collects the sample. Images PMID:14255663

  1. Quantitative Immunofluorescence Analysis of Nucleolus-Associated Chromatin.

    PubMed

    Dillinger, Stefan; Németh, Attila

    2016-01-01

    The nuclear distribution of eu- and heterochromatin is nonrandom, heterogeneous, and dynamic, which is mirrored by specific spatiotemporal arrangements of histone posttranslational modifications (PTMs). Here we describe a semiautomated method for the analysis of histone PTM localization patterns within the mammalian nucleus using confocal laser scanning microscope images of fixed, immunofluorescence stained cells as data source. The ImageJ-based process includes the segmentation of the nucleus, furthermore measurements of total fluorescence intensities, the heterogeneity of the staining, and the frequency of the brightest pixels in the region of interest (ROI). In the presented image analysis pipeline, the perinucleolar chromatin is selected as primary ROI, and the nuclear periphery as secondary ROI. PMID:27576710

  2. A brain proteome profile in rats exposed to methylmercury or thimerosal (ethylmercury).

    PubMed

    de Oliveira Souza, Vanessa Cristina; de Marco, Kátia Cristina; Laure, Hélen Julie; Rosa, José Cesar; Barbosa, Fernando

    2016-01-01

    Exposure to organomercurials has been associated with harmful effects on the central nervous system (CNS). However, the mechanisms underlying organomercurial-mediated neurotoxic effects need to be elucidated. Exposure to toxic elements may promote cellular modifications such as alterations in protein synthesis in an attempt to protect tissues and organs from damage. In this context, the use of a "proteomic profile" is an important tool to identify potential early biomarkers or targets indicative of neurotoxicity. The aim of this study was to investigate potential modifications in rat cerebral cell proteome following exposure to methylmercury (MeHg) or ethylmercury (EtHg). For MeHg exposure, animals were administered by gavage daily 140 µg/kg/d of Hg (as MeHg) for 60 d and sacrificed 24 h after the last treatment. For EtHg exposure, 800 µg/kg/d of Hg (as EtHg) was given intramuscularly (im) in a single dose and rats were sacrificed after 4 h. Control groups received saline either by gavage or im. After extraction of proteins from whole brain samples and separation by two-dimensional electrophoresis (2-DE), 26 differentially expressed proteins were identified from exposed animals by matrix-assisted laser desorption ionization-time of flight (MALDI-TOF/TOF). Both MeHg and EtHg exposure induced an overexpression of calbindin, a protein that acts as a neuroprotective agent by (1) adjusting the concentration of Ca(2+) within cells and preventing neurodegenerative diseases and (2) decreasing expression of glutamine synthetase, a crucial protein involved in regulation of glutamate concentration in synaptic cleft. In contrast, expression of superoxide dismutase (SOD), a protein involved in antioxidant defense, was elevated in brain of MeHg-exposed animals. Taken together, our data provide new valuable information on the possible molecular mechanisms associated with MeHg- and EtHg-mediated toxicity in cerebral tissue. These observed protein alterations may be considered as

  3. Methylmercury effects on migratory behaviour in glass eels (Anguilla anguilla): an experimental study using isotopic tracers.

    PubMed

    Claveau, Julie; Monperrus, Mathilde; Jarry, Marc; Baudrimont, Magalie; Gonzalez, Patrice; Cavalheiro, Joana; Mesmer-Dudons, Nathalie; Bolliet, Valérie

    2015-05-01

    The effect of methylmercury (MeHg) on glass eels' propensity to migrate, mitochondrial activity and antioxidative defence systems was investigated. Marine glass eels were first sorted in an experimental flume according to their response to dusk. Fish responding to the decrease in light intensity by ascending in the water column and moving with or against the flow were considered as having a high propensity to migrate (migrant). Glass eels still sheltering at the end of the 24 h catching period were considered as having a low propensity to migrate and were called non-migrant. Migrant and non-migrant glass eels were then individually tagged and exposed to isotopically enriched (201)MeHg (50 ng L(-1)) for 11 days. The effect of contamination was studied on muscle fibre structure, and the expression level of genes involved in mitochondrial activity and antioxidative defence systems. To investigate the effect of MeHg on glass eel behaviour, migrant and non-migrant glass eels were sorted again and the bioaccumulation of (201)MeHg and its demethylation product ((201)Hg(II)) were determined for each individual. MeHg exposure increased activity in non-migrant glass eels but not migratory behaviour. Contamination affected mitochondrial structure and metabolism and suggests a higher oxidative stress and activation of antioxidative defence systems in non-migrant glass eels. Overall, our results suggest that exposure to MeHg might induce an increase in energy expenditure and a higher vulnerability to predation in non-migrant glass eels in the wild. PMID:25797033

  4. A bout analysis reveals age-related methylmercury neurotoxicity and nimodipine neuroprotection.

    PubMed

    Shen, Andrew Nathanael; Cummings, Craig; Pope, Derek; Hoffman, Daniel; Newland, M Christopher

    2016-09-15

    Age-related deficits in motor and cognitive functioning may be driven by perturbations in calcium (Ca(2+)) homeostasis in nerve terminals, mechanisms that are also thought to mediate the neurotoxicity of methylmercury (MeHg). Calcium-channel blockers (CCBs) protect against MeHg toxicity in adult mice, but little is known about their efficacy in other age groups. Two age groups of BALB/c mice were exposed to 0 or 1.2mg/kg/day MeHg and 0 or 20mg/kg/day of the CCB nimodipine for approximately 8.5 months. Adults began exposure on postnatal day (PND) 72 and the retired breeders on PND 296. High-rate operant behavior was maintained under a percentile schedule, which helped to decouple response rate from reinforcer rate. Responding was analyzed using a log-survivor bout analysis approach that partitioned behavior into high-rate bouts separated by pauses. MeHg-induced mortality did not depend on age but nimodipine neuroprotection was age-dependent, with poorer protection occurring in older mice. Within-bout response rate (a marker of sensorimotor function) was more sensitive to MeHg toxicity than bout-initiation rate (a marker of motivation). Within-bout rate declined almost 2 months prior to overt signs of toxicity for the MeHg-only retired breeders but not adults, suggesting greater delay to toxicity in younger animals. Motor-based decrements also appeared in relatively healthy adult MeHg+NIM animals. Aging appeared to alter the processes underlying Ca(2+) homeostasis thereby diminishing protection by nimodipine, even in mice that have not reached senescence. The study of MeHg exposure presents an experimental model by which to study potential mechanisms of aging. PMID:27196441

  5. Whole-lake nitrate addition for control of methylmercury in mercury-contaminated Onondaga Lake, NY.

    PubMed

    Matthews, David A; Babcock, David B; Nolan, John G; Prestigiacomo, Anthony R; Effler, Steven W; Driscoll, Charles T; Todorova, Svetoslava G; Kuhr, Kenneth M

    2013-08-01

    Methylmercury (MeHg) strongly bioaccumulates in aquatic food webs resulting in exposure to humans and wildlife through consumption of fish. Production of MeHg is promoted by anaerobic conditions and the supply of inorganic Hg (Hg(2+)), sulfate (SO4(2-)), and labile organic carbon. The anaerobic sediments of stratified lakes are particularly active zones for methylation of Hg(2+) and can be an important source of MeHg to the water column during summer anoxia and fall turnover. Nitrate (NO3(-)) addition has recently been proposed as a novel approach for the control of MeHg accumulation in the hypolimnia of Hg-contaminated lakes. In 2011, a whole-lake NO3(-) addition pilot test was conducted in Hg-contaminated Onondaga Lake, NY with the objective of limiting release of MeHg from the pelagic sediments to the hypolimnion through maintenance of NO3(-)-N concentrations >1mgN/L. A liquid calcium-nitrate solution was added to the hypolimnion as a neutrally buoyant plume approximately three times per week during the summer stratification interval. Maximum hypolimnetic concentrations of MeHg and soluble reactive phosphorus (SRP) decreased 94% and 95% from 2009 levels, suggesting increased sorption to Fe and Mn oxyhydroxides in surficial sediments as the regulating mechanism. Increased MeHg concentrations in the upper waters during fall turnover, which had been a generally recurring pattern, did not occur in 2011, resulting in decreased exposure of aquatic organisms to MeHg. Over the 1992-2011 interval, the hypolimnetic NO3(-) supply explained 85% and 95% of the interannual variations in hypolimnetic accumulations of SRP and MeHg, respectively. PMID:23683521

  6. Modulation of methylmercury uptake by methionine: Prevention of mitochondrial dysfunction in rat liver slices by a mimicry mechanism

    SciTech Connect

    Roos, Daniel Henrique; Puntel, Robson Luiz; Farina, Marcelo; Aschner, Michael; Bohrer, Denise; Rocha, Joao Batista T.; Vargas Barbosa, Nilda B. de

    2011-04-01

    Methylmercury (MeHg) is an ubiquitous environmental pollutant which is transported into the mammalian cells when present as the methylmercury-cysteine conjugate (MeHg-Cys). With special emphasis on hepatic cells, due to their particular propensity to accumulate an appreciable amount of Hg after exposure to MeHg, this study was performed to evaluate the effects of methionine (Met) on Hg uptake, reactive species (RS) formation, oxygen consumption and mitochondrial function/cellular viability in both liver slices and mitochondria isolated from these slices, after exposure to MeHg or the MeHg-Cys complex. The liver slices were pre-treated with Met (250 {mu}M) 15 min before being exposed to MeHg (25 {mu}M) or MeHg-Cys (25 {mu}M each) for 30 min at 37 {sup o}C. The treatment with MeHg caused a significant increase in the Hg concentration in both liver slices and mitochondria isolated from liver slices. Moreover, the Hg uptake was higher in the group exposed to the MeHg-Cys complex. In the DCF (dichlorofluorescein) assay, the exposure to MeHg and MeHg-Cys produced a significant increase in DFC reactive species (DFC-RS) formation only in the mitochondria isolated from liver slices. As observed with Hg uptake, DFC-RS levels were significantly higher in the mitochondria treated with the MeHg-Cys complex compared to MeHg alone. MeHg exposure also caused a marked decrease in the oxygen consumption of liver slices when compared to the control group, and this effect was more pronounced in the liver slices treated with the MeHg-Cys complex. Similarly, the loss of mitochondrial activity/cell viability was greater in liver slices exposed to the MeHg-Cys complex when compared to slices treated only with MeHg. In all studied parameters, Met pre-treatment was effective in preventing the MeHg- and/or MeHg-Cys-induced toxicity in both liver slices and mitochondria. Part of the protection afforded by Met against MeHg may be related to a direct interaction with MeHg or to the competition

  7. Modulation of methylmercury uptake by methionine: Prevention of mitochondrial dysfunction in rat liver slices by a mimicry mechanism

    PubMed Central

    Roos, Daniel Henrique; Puntel, Robson Luiz; Farina, Marcelo; Aschner, Michael; Bohrer, Denise; Rocha, João Batista T.; de Vargas Barbosa, Nilda B.

    2016-01-01

    Methylmercury (MeHg) is an ubiquitous environmental pollutant which is transported into the mammalian cells when present as the methylmercury-cysteine conjugate (MeHg–Cys). With special emphasis on hepatic cells, due to their particular propensity to accumulate an appreciable amount of Hg after exposure to MeHg, this study was performed to evaluate the effects of methionine (Met) on Hg uptake, reactive species (RS) formation, oxygen consumption and mitochondrial function/cellular viability in both liver slices and mitochondria isolated from these slices, after exposure to MeHg or the MeHg–Cys complex. The liver slices were pre-treated with Met (250 μM) 15 min before being exposed to MeHg (25 μM) or MeHg–Cys (25 μM each) for 30 min at 37 °C. The treatment with MeHg caused a significant increase in the Hg concentration in both liver slices and mitochondria isolated from liver slices. Moreover, the Hg uptake was higher in the group exposed to the MeHg–Cys complex. In the DCF (dichlorofluorescein) assay, the exposure to MeHg and MeHg–Cys produced a significant increase in DFC reactive species (DFC-RS) formation only in the mitochondria isolated from liver slices. As observed with Hg uptake, DFC-RS levels were significantly higher in the mitochondria treated with the MeHg–Cys complex compared to MeHg alone. MeHg exposure also caused a marked decrease in the oxygen consumption of liver slices when compared to the control group, and this effect was more pronounced in the liver slices treated with the MeHg–Cys complex. Similarly, the loss of mitochondrial activity/cell viability was greater in liver slices exposed to the MeHg–Cys complex when compared to slices treated only with MeHg. In all studied parameters, Met pre-treatment was effective in preventing the MeHg-and/or MeHg–Cys-induced toxicity in both liver slices and mitochondria. Part of the protection afforded by Met against MeHg may be related to a direct interaction with MeHg or to the

  8. Analysis of rapid alternating movements in Cree subjects exposed to methylmercury and in subjects with neurological deficits.

    PubMed

    Beuter, A; de Geoffroy, A; Edwards, R

    1999-01-01

    To quantify rapid alternating movements (RAMs) we used a simple prototype developed in our laboratory that requires the subject to rotate two hand-held foam spheres connected to optical encoders via flexible rods. Ninety-six participants, including 30 control subjects, 36 Cree subjects exposed to methylmercury, 21 subjects with Parkinson's disease, 6 subjects with cerebellar deficits, and 3 subjects with essential tremor, were involved in the study (though data for 5 were later removed). Twelve characteristics were developed and calculated from the raw data. Conditions examined included two hands at natural cadence (NC2), right and left hands separately at fast cadence (FCl), and both hands at fast cadence (FC2). Two ratios (FC2/NC2) and (FC2/FC1) combining these conditions were also examined. Test-retest reliability was >0.80 for most characteristics but was <0.70 for some characteristics, especially in the conditions executed at normal cadence. Correlations between characteristics and numbers of outliers with respect to the control group distribution were used to reduce the set of characteristics from 12 to 7 (i.e., duration, range, maximum slope, similarity in shape, smoothness, sharpness, and coherence). ANOVAs on the three largest groups generated significant results for most characteristics in the three conditions and the two ratios for Cree subjects and subjects with Parkinson's disease. ANOVAs on 3 age-matched groups (n=6) suggest that methylmercury affects the performance of the Cree subjects with the higher exposure, especially in terms of smoothness, sharpness, and coherence. These preliminary results suggest that this test is sufficiently specific and sensitive to characterize the performance of different groups of subjects. Ratios tend to improve discrimination for Cree subjects in a few characteristics but not for patients with Parkinson's disease. PMID:9931228

  9. Freshwater discharges drive high levels of methylmercury in Arctic marine biota.

    PubMed

    Schartup, Amina T; Balcom, Prentiss H; Soerensen, Anne L; Gosnell, Kathleen J; Calder, Ryan S D; Mason, Robert P; Sunderland, Elsie M

    2015-09-22

    Elevated levels of neurotoxic methylmercury in Arctic food-webs pose health risks for indigenous populations that consume large quantities of marine mammals and fish. Estuaries provide critical hunting and fishing territory for these populations, and, until recently, benthic sediment was thought to be the main methylmercury source for coastal fish. New hydroelectric developments are being proposed in many northern ecosystems, and the ecological impacts of this industry relative to accelerating climate changes are poorly characterized. Here we evaluate the competing impacts of climate-driven changes in northern ecosystems and reservoir flooding on methylmercury production and bioaccumulation through a case study of a stratified sub-Arctic estuarine fjord in Labrador, Canada. Methylmercury bioaccumulation in zooplankton is higher than in midlatitude ecosystems. Direct measurements and modeling show that currently the largest methylmercury source is production in oxic surface seawater. Water-column methylation is highest in stratified surface waters near the river mouth because of the stimulating effects of terrestrial organic matter on methylating microbes. We attribute enhanced biomagnification in plankton to a thin layer of marine snow widely observed in stratified systems that concentrates microbial methylation and multiple trophic levels of zooplankton in a vertically restricted zone. Large freshwater inputs and the extensive Arctic Ocean continental shelf mean these processes are likely widespread and will be enhanced by future increases in water-column stratification, exacerbating high biological methylmercury concentrations. Soil flooding experiments indicate that near-term changes expected from reservoir creation will increase methylmercury inputs to the estuary by 25-200%, overwhelming climate-driven changes over the next decade. PMID:26351688

  10. Freshwater discharges drive high levels of methylmercury in Arctic marine biota

    PubMed Central

    Schartup, Amina T.; Balcom, Prentiss H.; Soerensen, Anne L.; Gosnell, Kathleen J.; Calder, Ryan S. D.; Mason, Robert P.; Sunderland, Elsie M.

    2015-01-01

    Elevated levels of neurotoxic methylmercury in Arctic food-webs pose health risks for indigenous populations that consume large quantities of marine mammals and fish. Estuaries provide critical hunting and fishing territory for these populations, and, until recently, benthic sediment was thought to be the main methylmercury source for coastal fish. New hydroelectric developments are being proposed in many northern ecosystems, and the ecological impacts of this industry relative to accelerating climate changes are poorly characterized. Here we evaluate the competing impacts of climate-driven changes in northern ecosystems and reservoir flooding on methylmercury production and bioaccumulation through a case study of a stratified sub-Arctic estuarine fjord in Labrador, Canada. Methylmercury bioaccumulation in zooplankton is higher than in midlatitude ecosystems. Direct measurements and modeling show that currently the largest methylmercury source is production in oxic surface seawater. Water-column methylation is highest in stratified surface waters near the river mouth because of the stimulating effects of terrestrial organic matter on methylating microbes. We attribute enhanced biomagnification in plankton to a thin layer of marine snow widely observed in stratified systems that concentrates microbial methylation and multiple trophic levels of zooplankton in a vertically restricted zone. Large freshwater inputs and the extensive Arctic Ocean continental shelf mean these processes are likely widespread and will be enhanced by future increases in water-column stratification, exacerbating high biological methylmercury concentrations. Soil flooding experiments indicate that near-term changes expected from reservoir creation will increase methylmercury inputs to the estuary by 25–200%, overwhelming climate-driven changes over the next decade. PMID:26351688

  11. Machine-based method for multiplex in situ molecular characterization of tissues by immunofluorescence detection

    PubMed Central

    Yarilin, Dmitry; Xu, Ke; Turkekul, Mesruh; Fan, Ning; Romin, Yevgeniy; Fijisawa, Sho; Barlas, Afsar; Manova-Todorova, Katia

    2015-01-01

    Immunofluorescent staining is an informative tool that is widely used in basic research. Automation of immunostaining improves reproducibility and quality of the results. Up to now, use of automation in immunofluorescent staining was mostly limited to one marker. Here we present tyramide signal amplification based method of multiple marker immunofluorescent detection, including detection of antibodies, raised in the same species, in tissue sections and cultured cells. This method can be beneficial for both basic and clinical research. PMID:25826597

  12. Epidermal innervation morphometry by immunofluorescence and bright-field microscopy.

    PubMed

    Nolano, Maria; Biasiotta, Antonella; Lombardi, Raffaella; Provitera, Vincenzo; Stancanelli, Annamaria; Caporaso, Giuseppe; Santoro, Lucio; Merkies, Ingemar S J; Truini, Andrea; Porretta-Serapiglia, Carla; Cazzato, Daniele; Dacci, Patrizia; Vitale, Dino F; Lauria, Giuseppe

    2015-12-01

    We investigated the agreement between simple indirect immunofluorescence (IF) and bright-field immunohistochemistry (BFI) on free-floating sections for intraepidermal nerve fiber density (IENFD) quantification. Fifty-five healthy subjects and 63 patients with probable small fiber neuropathy (SFN) underwent two adjacent skin biopsies at the distal leg processed by IF and BFI technique. Agreement between IENFD pairs obtained by each method was assessed by Bland-Altman testing. The area under the curve of the receiving operating characteristics (ROC) curves was used to compare the discrimination ability. The diagnostic judgment was based on sex and age-adjusted normative values. IF and BFI showed good correlation (r = 0.81), with a ratio of about 2:1 and a mean difference of 5.5 ± 3.0 IENF per millimeter between paired measures, as demonstrated by linear regression and Bland-Altman test analyses. The square root transformation confirmed a Poisson distribution of the data and a fixed bias between IF and BFI measurements. The ROC curves analysis demonstrated a striking overlap between IF and BFI (0.83 and 0.82; p = 0.72). The diagnosis of SFN disagreed in only 6.7% of cases when the judgment was based on a difference of >1 IENF from 5% cut-off value. IF and BFI showed comparable diagnostic efficiency when referred to appropriate normative reference values. PMID:26309146

  13. Immunofluorescence Analysis of Endogenous and Exogenous Centromere-kinetochore Proteins.

    PubMed

    Niikura, Yohei; Kitagawa, Katsumi

    2016-01-01

    "Centromeres" and "kinetochores" refer to the site where chromosomes associate with the spindle during cell division. Direct visualization of centromere-kinetochore proteins during the cell cycle remains a fundamental tool in investigating the mechanism(s) of these proteins. Advanced imaging methods in fluorescence microscopy provide remarkable resolution of centromere-kinetochore components and allow direct observation of specific molecular components of the centromeres and kinetochores. In addition, methods of indirect immunofluorescent (IIF) staining using specific antibodies are crucial to these observations. However, despite numerous reports about IIF protocols, few discussed in detail problems of specific centromere-kinetochore proteins.(1-4) Here we report optimized protocols to stain endogenous centromere-kinetochore proteins in human cells by using paraformaldehyde fixation and IIF staining. Furthermore, we report protocols to detect Flag-tagged exogenous CENP-A proteins in human cells subjected to acetone or methanol fixation. These methods are useful in detecting and quantifying endogenous centromere-kinetochore proteins and Flag-tagged CENP-A proteins, including those in human cells. PMID:26967065

  14. Multiplexed immunofluorescence delineates proteomic cancer cell states associated with metabolism

    PubMed Central

    Sood, Anup; Miller, Alexandra M.; Brogi, Edi; Sui, Yunxia; Armenia, Joshua; McDonough, Elizabeth; Santamaria-Pang, Alberto; Carlin, Sean; Stamper, Aleksandra; Campos, Carl; Pang, Zhengyu; Li, Qing; Port, Elisa; Graeber, Thomas G.; Schultz, Nikolaus; Ginty, Fiona; Larson, Steven M.; Mellinghoff, Ingo K.

    2016-01-01

    The phenotypic diversity of cancer results from genetic and nongenetic factors. Most studies of cancer heterogeneity have focused on DNA alterations, as technologies for proteomic measurements in clinical specimen are currently less advanced. Here, we used a multiplexed immunofluorescence staining platform to measure the expression of 27 proteins at the single-cell level in formalin-fixed and paraffin-embedded samples from treatment-naive stage II/III human breast cancer. Unsupervised clustering of protein expression data from 638,577 tumor cells in 26 breast cancers identified 8 clusters of protein coexpression. In about one-third of breast cancers, over 95% of all neoplastic cells expressed a single protein coexpression cluster. The remaining tumors harbored tumor cells representing multiple protein coexpression clusters, either in a regional distribution or intermingled throughout the tumor. Tumor uptake of the radiotracer 18F-fluorodeoxyglucose was associated with protein expression clusters characterized by hormone receptor loss, PTEN alteration, and HER2 gene amplification. Our study demonstrates an approach to generate cellular heterogeneity metrics in routinely collected solid tumor specimens and integrate them with in vivo cancer phenotypes. PMID:27182557

  15. IFDOTMETER: A New Software Application for Automated Immunofluorescence Analysis.

    PubMed

    Rodríguez-Arribas, Mario; Pizarro-Estrella, Elisa; Gómez-Sánchez, Rubén; Yakhine-Diop, S M S; Gragera-Hidalgo, Antonio; Cristo, Alejandro; Bravo-San Pedro, Jose M; González-Polo, Rosa A; Fuentes, José M

    2016-04-01

    Most laboratories interested in autophagy use different imaging software for managing and analyzing heterogeneous parameters in immunofluorescence experiments (e.g., LC3-puncta quantification and determination of the number and size of lysosomes). One solution would be software that works on a user's laptop or workstation that can access all image settings and provide quick and easy-to-use analysis of data. Thus, we have designed and implemented an application called IFDOTMETER, which can run on all major operating systems because it has been programmed using JAVA (Sun Microsystems). Briefly, IFDOTMETER software has been created to quantify a variety of biological hallmarks, including mitochondrial morphology and nuclear condensation. The program interface is intuitive and user-friendly, making it useful for users not familiar with computer handling. By setting previously defined parameters, the software can automatically analyze a large number of images without the supervision of the researcher. Once analysis is complete, the results are stored in a spreadsheet. Using software for high-throughput cell image analysis offers researchers the possibility of performing comprehensive and precise analysis of a high number of images in an automated manner, making this routine task easier. PMID:26303944

  16. Deformability-based cell selection with downstream immunofluorescence analysis.

    PubMed

    Shaw Bagnall, Josephine; Byun, Sangwon; Miyamoto, David T; Kang, Joon Ho; Maheswaran, Shyamala; Stott, Shannon L; Toner, Mehmet; Manalis, Scott R

    2016-05-16

    Mechanical properties of single cells have been shown to relate to cell phenotype and malignancy. However, until recently, it has been difficult to directly correlate each cell's biophysical characteristics to its molecular traits. Here, we present a cell sorting technique for use with a suspended microchannel resonator (SMR), which can measure biophysical characteristics of a single cell based on the sensor's record of its buoyant mass as well as its precise position while it traverses through a constricted microfluidic channel. The measurement provides information regarding the amount of time a cell takes to pass through a constriction (passage time), as related to the cell's deformability and surface friction, as well as the particular manner in which it passes through. In the method presented here, cells of interest are determined based on passage time, and are collected off-chip for downstream immunofluorescence imaging. The biophysical single-cell SMR measurement can then be correlated to the molecular expression of the collected cell. This proof-of-principle is demonstrated by sorting and collecting tumor cells from cell line-spiked blood samples as well as a metastatic prostate cancer patient blood sample, identifying them by their surface protein expression and relating them to distinct SMR signal trajectories. PMID:26999591

  17. Purification, characterization, and immunofluorescence localization of Saccharomyces cerevisiae capping protein.

    PubMed

    Amatruda, J F; Cooper, J A

    1992-06-01

    Capping protein binds the barbed ends of actin filaments and nucleates actin filament assembly in vitro. We purified capping protein from Saccharomyces cervisiae. One of the two subunits is the product of the CAP2 gene, which we previously identified as the gene encoding the beta subunit of capping protein based on its sequence similarity to capping protein beta subunits in chicken and Dictyostelium (Amatruda, J. F., J. F. Cannon, K. Tatchell, C. Hug, and J. A. Cooper. 1990. Nature (Lond.) 344:352-354). Yeast capping protein has activity in critical concentration and low-shear viscometry assays consistent with barbed-end capping activity. Like chicken capping protein, yeast capping protein is inhibited by PIP2. By immunofluorescence microscopy yeast capping protein colocalizes with cortical actin spots at the site of bud emergence and at the tips of growing buds and shmoos. In contrast, capping protein does not colocalize with actin cables or with actin rings at the site of cytokinesis. PMID:1315784

  18. Detection of CXCR2 cytokine receptor surface expression using immunofluorescence.

    PubMed

    Lam, Clarissa; Pavel, Mahmud Arif; Kashyap, Parul; Salehi-Najafabadi, Zahra; Valentino, Victoria; Yu, Yong

    2014-01-01

    The interleukin-8 (IL-8, CXCL8) chemokine, also known as the neutrophil chemotactic factor, is a cytokine that plays a key role in inflammatory response, cell proliferation, migration, and survival. IL-8 expression is increased not only in inflammatory disorders, but also in many types of cancer, including prostate cancer. IL-8 acts as a ligand for the C-X-C chemokine receptor 2 (CXCR2) protein present on the cell plasma membrane. Binding of the IL-8 ligand to the CXCR2 receptor results in an intracellular signaling pathway mediated by GTP binding proteins coupled to the receptor itself. Knowledge of the CXCR2 expression levels facilitates the understanding of the role and function of IL-8. In this chapter, we describe a protocol that uses the immunofluorescence method and confocal microscopy to analyze the CXCR2 surface expression in human prostate cancer cells. However, this protocol is easily adaptable to analyze the surface expression of other cytokine receptors in different cell types. PMID:24908306

  19. Borrelia burgdorferi visualized in Ixodes scapularis tick excrement by immunofluorescence.

    PubMed

    Patton, Toni G; Brandt, Kevin S; Gilmore, Robert D

    2012-11-01

    The enzootic cycle of Borrelia burgdorferi, the etiologic agent of Lyme disease, involves Ixodes spp. ticks and vertebrates. Resident tick Borrelia, harbored inside the midgut, are eventually expelled with the tick's saliva into the vertebrate host when a tick consumes a blood meal. During this 4- to 5-day feeding period I. scapularis will defecate onto the host's skin. Previously we detected borrelial DNA in tick feces throughout engorgement. In this study we report the microscopic examination for B. burgdorferi in nymphal excrement. Using immunofluorescence assays, we observed Borrelia in all mouse skin and capsule fecal swabs tested, although we could not culture the spirochetes. These results update our previous analysis by revealing that spirochetes can also be visualized in tick excrement. Furthermore, the results emphasize that borrelial contamination by defecation is a possibility, and that caution should be exercised by researchers investigating pathogen/host/vector interactions. The biological significance of the presence of non-culturable Borrelia in tick feces during engorgement is unclear. PMID:22651382

  20. Measuring Temporal Variability of Methylmercury and Methane in the Pore Waters of a Chesapeake Bay Tidal Marsh

    NASA Astrophysics Data System (ADS)

    Martin, K. R.; Oster, J.; Lapham, L.; Heyes, A.

    2015-12-01

    This study assesses the use of OsmoSampler technology to monitor methylmercury production in a tidal marsh and examines temporal variability of methylmercury in relation to controlling factors. We collected pore water samples in a Chesapeake Bay marsh using continuous pore-fluid sampling devices called OsmoSamplers. OsmoSampler technology has not previously been used to investigate mercury cycling. We designed systems using OsmoSamplers to collect pore water samples for methylmercury, methane, chloride, and sulfate analysis, sampling in a vegetated area and an area devegetated by clipping. Samples were collected over a 27 day period and stored in coils to create a temporal data set of in situ concentrations. This time series allows us to explore the methane-methylmercury connection and the effects of vegetation removal on methylmercury production. Some methanogens are known to methylate mercury, but the relative importance of the methane community in mercury methylation is not well understood. We hypothesized a positive correlation between methane and methylmercury production and a decrease in methylmercury production corresponding to vegetation removal. We also sought to demonstrate the feasibility of using OsmoSamplers to look at methylmercury flux in relation to these controls on mercury methylation. This study is a preliminary exploration of this technology in a marsh environment. Using our system we have successfully collected pore water samples. We present the temporal variability of measured concentrations with a discussion of adjustments for future long-term deployment.

  1. New method for detecting methylmercury by its enzymatic conversion to methane

    SciTech Connect

    Baldi, F. ); Filippelli, M. )

    1991-02-01

    A new method is suggested for determining methylmercury in biological samples. The determination is based on the use of whole cells of a broad-spectrum mercury-resistant bacterium, Pseudomonas putida, strain FB1, which is induced to produce the enzymes organomercurial lyase and mercuric reductase. These biocatalysts convert organomercurials to elemental mercury and their derivative hydrocarbons. The extraction procedure for methylmercury in biological samples follows the conventional toluene extraction method, which is retained until methylmercury is concentrated in an aqueous phase containing 0.01 M Na{sub 2}S{sub 2}O{sub 3}. This solution is mixed with bacterial cells in exponential growth phase and then incubated in microreaction vessels. A complete biological degradation of methylmercury to methane occurs. The efficiency of derivatization depends on the organomercurial concentration, the incubation time, and the cell density. The detection limit is 15 ng of methylmercury in 1 g of biological tissue and the coefficient of variation is 1.9% in 10 replicate samples with 100 ng/mL.

  2. Rapid changes in concentrations of essential elements in organs of rats exposed to methylmercury chloride and mercuric chloride as shown by simultaneous multielemental analysis.

    PubMed Central

    Muto, H; Shinada, M; Tokuta, K; Takizawa, Y

    1991-01-01

    An in vivo study of rats given a dominant lethal dose of methylmercury chloride (MMC) or mercuric chloride (HgCl2) was conducted to elucidate the rapid biotransformation of essential elements. The elements were measured by inductively coupled plasma atomic emission spectrometry. For the rat brain Zn concentrations were higher in the MMC group than in the HgCl2 and control groups. The highest Cu concentration was found in HgCl2 dosed rat liver. For the rat kidney the highest Zn concentration was seen in the MMC group. From principal component analysis on the time dependent behaviour of each element in rat organs, characteristics specific to Cu in the liver and kidney and Mn in the brain were found after exposure to HgCl2 and Ca and Zn in the brain after exposure to MMC. PMID:2064976

  3. Evidence of early nervous system dysfunction in Amazonian populations exposed to low-levels of methylmercury.

    PubMed

    Lebel, J; Mergler, D; Lucotte, M; Amorim, M; Dolbec, J; Miranda, D; Arantès, G; Rheault, I; Pichet, P

    1996-01-01

    There is increasing concern about the potential neurotoxic effects of exposure to methylmercury in Amazonian populations due to mercury (Hg) release from gold-mining activities. A preliminary study was undertaken in two villages on the Tapajos River, an effluent of the Amazon, situated over 200 km downstream from the extraction areas. The study population included 29 young adults (< or = 35 years), 14 women and 15 men, randomly chosen from a previous survey. Hair analyses were conducted with cold vapor atomic fluorescence spectrophotometry. Total hair Hg (THg) varied between 5.6 micrograms/g and 38.4 micrograms/gl, with MeHg levels from 72.2% to 93.3% of the THg. A quantitative behavioural neurophysiological test battery, designed for use under standard conditions, in an area without electricity and for persons with minimal education was administered to all participants. The results of visual testing showed that although all participants had good near and far visual acuity, color discrimination capacity (Lanthony D-15 desaturated panel) decreased with increasing THg (F = 4.1; p = 0.05); near visual contrast sensitivity profiles (Vistech 6000) and peripheral visual field profiles (Goldman Perimetry with Targets I and V) were reduced for those with the highest levels of THg. For the women, manual dexterity (Santa Ana, Helsinki version) decreased with increasing THg (F = 16.7; p < 0.01); this was not the case for the men. Although the women showed a tendency towards reduced grip strength, muscular fatigue did not vary with THg for either sex. The findings of this study demonstrate that it is possible, using a sensitive test battery, to detect alterations in nervous system functions, consistent with knowledge on Hg toxicity, at levels below the currently recognized threshold of 50 micrograms/g THg. PMID:8784826

  4. MRP2 involvement in renal proximal tubular elimination of methylmercury mediated by DMPS or DMSA

    SciTech Connect

    Zalups, Rudolfs K. Bridges, Christy C.

    2009-02-15

    2, 3-Dimercaptopropane-1-sulfonic acid (DMPS) and meso-2, 3-Dimercaptosuccinic acid (DMSA) are dithiols used to treat humans exposed to methylmercury (CH{sub 3}Hg{sup +}). After treatment, significant amounts of mercury are eliminated rapidly from the kidneys and are excreted in urine. In the present study, we extended our previous studies by testing the hypothesis that MRP2 mediates the secretion of DMPS or DMSA S-conjugates of CH{sub 3}Hg{sup +}. To test this hypothesis, the disposition of mercury was assessed in control and Mrp2-deficient (TR{sup -}) rats exposed intravenously to a 5.0-mg/kg dose of CH{sub 3}HgCl. Twenty-four and 28 h after exposure, groups of four control and four TR{sup -} rats were injected with saline, DMPS, or DMSA. Tissues were harvested 48 h later. Renal and hepatic contents of mercury were greater in saline-injected TR{sup -} rats than in controls. In contrast, the amounts of mercury excreted in urine and feces by TR{sup -} rats were less than those by controls. DMPS and DMSA significantly reduced the renal and hepatic content of mercury in both groups of rats, with the greatest reduction in controls. A significant increase in urinary and fecal excretion of mercury (which was greater in the controls) was also observed. Our findings in inside-out membrane vesicles prepared from hMRP2-transfected Sf9 cells show that uptake of DMPS and DMSA S-conjugates of CH{sub 3}Hg{sup +} was greater in the vesicles containing hMRP2 than in control vesicles. Overall, these dispositional findings indicate that MRP2 does play a role in DMPS- and DMSA-mediated elimination of mercury from the kidney.

  5. Identification and prioritization of management practices to reduce methylmercury exports from wetlands and irrigated agricultural lands.

    PubMed

    McCord, Stephen A; Heim, Wesley A

    2015-03-01

    The Sacramento-San Joaquin Delta's (Delta) beneficial uses for humans and wildlife are impaired by elevated methylmercury (MeHg) concentrations in fish. MeHg is a neurotoxin that bioaccumulates in aquatic food webs. The total maximum daily load (TMDL) implementation plan aimed at reducing MeHg in Delta fish obligates dischargers to conduct MeHg control studies. Over 150 stakeholders collaborated to identify 24 management practices (MPs) addressing MeHg nonpoint sources (NPS) in three categories: biogeochemistry (6), hydrology (14), and soil/vegetation (4). Land uses were divided into six categories: permanently and seasonally flooded wetlands, flooded and irrigated agricultural lands, floodplains, and brackish-fresh tidal marshes. Stakeholders scored MPs based on seven criteria: scientific certainty, costs, MeHg reduction potential, spatial applicability, technical capacity to implement, negative impacts to beneficial uses, and conflicting requirements. Semi-quantitative scoring for MPs applicable to each land use (totaling >400 individual scores) led to consensus-based prioritization. This process relied on practical experience from diverse and accomplished NPS stakeholders and synthesis of 17 previous studies. Results provide a comprehensive, stakeholder-driven prioritization of MPs for wetland and irrigated agricultural land managers. Final prioritization highlights the most promising MPs for practical application and control study, and a secondary set of MPs warranting further evaluation. MPs that address hydrology and soil/vegetation were prioritized because experiences were positive and implementation appeared more feasible. MeHg control studies will need to address the TMDL conundrum that MPs effective at reducing MeHg exports could both exacerbate MeHg exposure and contend with other management objectives on site. PMID:25566831

  6. Proteome profiling reveals regional protein alteration in cerebrum of common marmoset (Callithrix jacchus) exposed to methylmercury.

    PubMed

    Shao, Yueting; Yamamoto, Megumi; Figeys, Daniel; Ning, Zhibin; Chan, Hing Man

    2016-03-10

    Methylmercury (MeHg) is known to selectively damage the calcarine and precentral cortices along deep sulci and fissures in adult cases, but the detailed mechanism is still unclear. This study aims to identify and analyze the differential proteome expression in two regions of the cerebrum (the frontal lobe and the occipital lobe including the calcarine sulcus) of the common marmoset exposed to MeHg using a shot-gun proteomic approach. A total of 1045 and 1062 proteins were identified in the frontal lobe (FL) and occipital lobe (OL), of which, 62 and 89 proteins were found significantly changed with MeHg exposure. Functional enrichment/depletion analysis showed that the lipid metabolic process and proteolysis were affected in both two lobes. Functional changes in FL were characterized in cell cycle and cell division, sulfur compound metabolic process, microtubule-based process and glycerolipid metabolic process. In comparison, proteins were enriched in the functions of transport, carbohydrate metabolic process, chemical caused homeostasis and regulation of body fluid levels in OL. Pathway analysis predicted that vasopressin-regulated water reabsorption was disturbed in MeHg-treated FL. Our results showed that MeHg induced regional specific protein changes in FL and OL but with similar endpoint effects such as energy diminish and disruption of water transport. APOE and GPX1 were shown to be possible key proteins targeted by MeHg leading to multiple functional changes in OL. This is the first report of the whole proteome changes of primate cerebrum for MeHg neurotoxicity, and the results will contribute to the understanding of molecular basis of MeHg intoxication in humans. PMID:27012723

  7. Identification and Prioritization of Management Practices to Reduce Methylmercury Exports from Wetlands and Irrigated Agricultural Lands

    NASA Astrophysics Data System (ADS)

    McCord, Stephen A.; Heim, Wesley A.

    2015-03-01

    The Sacramento-San Joaquin Delta's (Delta) beneficial uses for humans and wildlife are impaired by elevated methylmercury (MeHg) concentrations in fish. MeHg is a neurotoxin that bioaccumulates in aquatic food webs. The total maximum daily load (TMDL) implementation plan aimed at reducing MeHg in Delta fish obligates dischargers to conduct MeHg control studies. Over 150 stakeholders collaborated to identify 24 management practices (MPs) addressing MeHg nonpoint sources (NPS) in three categories: biogeochemistry (6), hydrology (14), and soil/vegetation (4). Land uses were divided into six categories: permanently and seasonally flooded wetlands, flooded and irrigated agricultural lands, floodplains, and brackish-fresh tidal marshes. Stakeholders scored MPs based on seven criteria: scientific certainty, costs, MeHg reduction potential, spatial applicability, technical capacity to implement, negative impacts to beneficial uses, and conflicting requirements. Semi-quantitative scoring for MPs applicable to each land use (totaling >400 individual scores) led to consensus-based prioritization. This process relied on practical experience from diverse and accomplished NPS stakeholders and synthesis of 17 previous studies. Results provide a comprehensive, stakeholder-driven prioritization of MPs for wetland and irrigated agricultural land managers. Final prioritization highlights the most promising MPs for practical application and control study, and a secondary set of MPs warranting further evaluation. MPs that address hydrology and soil/vegetation were prioritized because experiences were positive and implementation appeared more feasible. MeHg control studies will need to address the TMDL conundrum that MPs effective at reducing MeHg exports could both exacerbate MeHg exposure and contend with other management objectives on site.

  8. A physiologically based toxicokinetic model for methylmercury in female American kestrels

    USGS Publications Warehouse

    Nichols, J.W.; Bennett, R.S.; Rossmann, R.; French, J.B.; Sappington, K.G.

    2010-01-01

    A physiologically based toxicokinetic (PBTK) model was developed to describe the uptake, distribution, and elimination of methylmercury (CH 3Hg) in female American kestrels. The model consists of six tissue compartments corresponding to the brain, liver, kidney, gut, red blood cells, and remaining carcass. Additional compartments describe the elimination of CH3Hg to eggs and growing feathers. Dietary uptake of CH 3Hg was modeled as a diffusion-limited process, and the distribution of CH3Hg among compartments was assumed to be mediated by the flow of blood plasma. To the extent possible, model parameters were developed using information from American kestrels. Additional parameters were based on measured values for closely related species and allometric relationships for birds. The model was calibrated using data from dietary dosing studies with American kestrels. Good agreement between model simulations and measured CH3Hg concentrations in blood and tissues during the loading phase of these studies was obtained by fitting model parameters that control dietary uptake of CH 3Hg and possible hepatic demethylation. Modeled results tended to underestimate the observed effect of egg production on circulating levels of CH3Hg. In general, however, simulations were consistent with observed patterns of CH3Hg uptake and elimination in birds, including the dominant role of feather molt. This model could be used to extrapolate CH 3Hg kinetics from American kestrels to other bird species by appropriate reassignment of parameter values. Alternatively, when combined with a bioenergetics-based description, the model could be used to simulate CH 3Hg kinetics in a long-term environmental exposure. ?? 2010 SETAC.

  9. Effects of photodemethylation on the methylmercury budget of boreal Norwegian lakes.

    PubMed

    Poste, Amanda E; Braaten, Hans Fredrik Veiteberg; de Wit, Heleen A; Sørensen, Kai; Larssen, Thorjørn

    2015-06-01

    Methylmercury (MeHg) concentrations in freshwater fish from southeastern Norway continue to increase, highlighting the need for a comprehensive understanding of MeHg sources, cycling, and degradation in the aquatic environment. The authors assessed the importance of photodemethylation in the MeHg budget of 4 Norwegian lakes. Photodemethylation rates were determined using incubation experiments with MeHg-spiked natural lake water. The authors determined full-spectrum exposure rates at all study sites and waveband-specific rates (photosynthetically active radiation, ultraviolet-A radiation, and ultraviolet-B radiation) at 1 clear-water (Sognsvann) and 1 humic (Langtjern) site. No significant differences in photodemethylation rates between the sites were found, and the authors' observed rates agreed with available literature for lake and wetland waters. The authors paired experimentally derived photodemethylation rates with lake-specific incident irradiation, light attenuation, and MeHg concentrations to estimate MeHg loss through photodemethylation for the study sites. For Langtjern, losses through photodemethylation equalled 27% of total annual inputs, highlighting the importance of photodemethylation in the MeHg budget. Furthermore, the authors assessed how changes in terrestrial dissolved organic carbon (DOC) exported to freshwaters and climate-driven reductions in ice cover duration may affect MeHg losses through photodemethylation. Results suggest that future increases in DOC may lead to higher aqueous MeHg concentrations in boreal lakes due to increased DOC-associated MeHg inputs paired with significant decreases in the loss of MeHg through photodemethylation due to increased light attenuation. PMID:25663582

  10. Simple analysis of total mercury and methylmercury in seafood using heating vaporization atomic absorption spectrometry.

    PubMed

    Yoshimoto, Keisuke; Anh, Hoang Thi Van; Yamamoto, Atsushi; Koriyama, Chihaya; Ishibashi, Yasuhiro; Tabata, Masaaki; Nakano, Atsuhiro; Yamamoto, Megumi

    2016-01-01

    This study aimed to develop a simpler method for determining total mercury (T-Hg) and methylmercury (MeHg) in biological samples by using methyl isobutyl ketone (MIBK) in the degreasing step. The fat in the samples was extracted by MIBK to the upper phase. T-Hg transferred into the water phase. This was followed by the extraction of MeHg from the water phase using HBr, CuCl2 and toluene. The MeHg fraction was reverse-extracted into L-cysteine-sodium acetate solution from toluene. The concentrations of T-Hg and MeHg were determined by heating vaporization atomic absorption spectrometry. Certified reference materials for T-Hg and MeHg in hair and fish were accurately measured using this method. This method was then applied to determine T-Hg and MeHg concentrations in the muscle, liver and gonads of seafood for the risk assessment of MeHg exposure. The mean T-Hg and MeHg concentrations in squid eggs were 0.023 and 0.022 µg/g, and in squid nidamental glands 0.052 and 0.049 µg/g, respectively. The MeHg/T-Hg ratios in the eggs and nidamental glands of squid were 94.4% and 96.5%, respectively. The mean T-Hg and MeHg concentrations in the gonads of sea urchins were 0.043 and 0.001 µg/g, respectively, with a MeHg/T-Hg ratio of 3.5%. We developed an efficient analytical method for T-Hg and MeHg using MIBK in the degreasing step. The new information on MeHg concentration and MeHg/T-Hg ratios in the egg or nidamental glands of squid and gonads of sea urchin will also be useful for risk assessment of mercury in seafood. PMID:27432235

  11. Tissue distribution and histopathological effects of dietary methylmercury in benthic grubby Myoxocephalus aenaeus

    SciTech Connect

    Pelletier, E.; Audet, C.

    1995-05-01

    There is a need to test deterministic models predicting the behavior and effects of chemicals on aquatic systems by conducting experiments with more than one trophic step at a time. This approach requires the set-up of an experimental food chain in pounds or mesocosm facilities which can be used for dietary uptake studies and assessment of sublethal stress induced by contaminated food. In the course of our current research program at the INRS marine mesocosms facilities, a model benthic food chain including inter- and sub-tidal species such as the mussel (Mytilus edulis), clam (Mya arenaria), starfish (Leptasterias polaris), polychaete (Nereis virens), amphipod (Gammarus sp.), gastropod (Buccinum undatum), and fishes (Pleuronectec americanus, Myoxocephalus aenaeus), is used for testing food uptake models and for the development of sublethal toxicity tests which could be used in the environmental assessment of coastal and estuarine waters. Among these test organisms, the grubby (M. aenaeus) is a small coastal fish (12-15 cm) characterized by a broad head. The grubby is tolerant of water temperature and salinity variations and lives on a wide variety of bottom strata at low depths. The grubby is carnivorous and consumes a wide variety of molluscs and the young of many species of fish. Because of its size, its estuarine and coastal distribution and its large spectrum of prey, this species was seen as an ideal fish to fit into our experimental food chain model. This paper reports a preliminary experiment designed to measure distribution of mercury in tissues and to test the response of various histopathological and biochemical stress indicators in grubby exposed to dietary contamination by methylmercury (MeHg) for a 20-day exposure period. MeHg was chosen because it is rapidly bioaccumulated by most living organisms and its toxicity has been studied for decades in numerous aquatic ecosystems. 17 refs., 2 tabs.

  12. Warming increases methylmercury production in an Arctic soil

    DOE PAGESBeta

    Yang, Ziming; Fang, Wei; Lu, Xia; Sheng, Guo-Ping; Graham, David E.; Liang, Liyuan; Wullschleger, Stan D.; Gu, Baohua

    2016-04-29

    The rapid temperature rise in Arctic permafrost concerns not only the degradation of stored soil organic carbon (SOC) and climate feedback, but also the production and bioaccumulation of methylmercury (MeHg) that may endanger humans, as well as wildlife in terrestrial, aquatic, and marine ecosystems. Decomposition of SOC provides an energy source for microbial methylation, although little is known how rapid permafrost thaw affects Hg methylation and how SOC degradation is coupled to MeHg biosynthesis. We describe rates of MeHg production in Arctic soils from an 8-month warming microcosm experiment under anoxic conditions. MeHg production increased >10 fold in both organic-more » and the mineral-rich soil layers at a warmer temperature (8 C) compared to a sub-zero temperature ( 2 C). MeHg production was positively correlated to methane and ferrous ion concentrations, suggesting that Hg methylation is coupled with methanogenesis and iron reduction. Labile SOC, such as reducing sugars and alcohol, were particularly effective in fueling the initial rapid biosynthesis of MeHg. In freshly amended Hg we found that there was more bioavailable than existing Hg in the mineral soil. Finally, the data indicate that climate warming and permafrost thaw could greatly enhance MeHg production, thereby impacting Arctic aquatic and marine ecosystems through biomagnification in the food web.« less

  13. Improvements of reliability for methylmercury determination in environmental samples.

    PubMed

    Yang, Dan-Yi; Truong, Hoang-Yen Thi; Chen, Yu-Wei; Belzile, Nelson

    2009-02-01

    The determination of methylmercury (MeHg) in environmental samples by ethylation derivation-gas chromatography-atomic fluorescence spectrometry (ED-GC-AFS) is associated with an intimate problem of water moisture accumulation introduced in the ethylation step, which enters the detection system and cause a spectroscopic interference. With a simple modification on the GC-AFS system, this problem was eliminated and the analytical quality of the measurements was significantly improved. The presence of dissolved sulfide in samples can also cause serious chemical interference in the ethylation step resulting in lower or total loss of the MeHg signal. It was found that a masking system of CuSO(4)-Na(2)C(2)O(4) was able to eliminate this interference. With this system, the accurate determination of trace amount of MeHg in high dissolved sulfide containing samples was achieved. Satisfactory analytical results were obtained with the certified reference sediment IAEA405, sulfate reducing bacteria culture and sulfide containing water samples. The limit of detection and quantitation of this masking system is 0.01 and 0.04ngL(-1) respectively. Other factors affecting ethylation are also discussed. PMID:19166718

  14. Effect of methylmercury on the rat mast cell degranulation

    NASA Astrophysics Data System (ADS)

    Graevskaya, E. E.; Yasutake, A.; Aramai, R.; Rubin, A. B.

    2003-05-01

    Methylmercury is the well-known neurotoxicant as weil as a modulator of the immune system. We investigated the effects of MeHg on the rat mast cell degranulation induced by nonimmunological stimuli (the selective liberator of histamine, compound 48/80, and calcium ionophore A23187) both in vivo and in vitro. In 8, 12 and 15 days afterthe final administration of MeHg we observed the suppression of calcium ionophore A23187-and 48/80-induced histamine release, which enhanced with time. In experiments in vitro incubation of peritoneal mast cells with MeHg alone in the dose range 10^{-8} to 10^{-6} did not induce mast cell degranulation, however modified the activation of mast cells by compound 48/80, and calcium ionophore A23187. We observed activation of stimulated secretion by preliminary incubation with low dose of MeHg 10^{-8} M and inhibition by dose of MeHg 10^{-6} M. These results show that MeHg treatment can modify mast cell function in vivo and in vitro and provide insight into the understanding what role this cell has in the pathogenesis of Minamata disease-comlected disorders.

  15. Methylmercury cycling in High Arctic wetland ponds: sources and sinks.

    PubMed

    Lehnherr, Igor; St Louis, Vincent L; Emmerton, Craig A; Barker, Joel D; Kirk, Jane L

    2012-10-01

    The sources of methylmercury (MeHg; the toxic form of mercury that is biomagnified through foodwebs) to Arctic freshwater organisms have not been clearly identified. We used a mass balance approach to quantify MeHg production in two wetland ponds in the Lake Hazen region of northern Ellesmere Island, NU, in the Canadian High Arctic and to evaluate the importance of these systems as sources of MeHg to Arctic foodwebs. We show that internal production (1.8-40 ng MeHg m(-2) d(-1)) is a much larger source of MeHg than external inputs from direct atmospheric deposition (0.029-0.051 ng MeHg m(-2) d(-1)), as expected. Furthermore, MeHg cycling in these systems is dominated by Hg(II) methylation and MeHg photodemethylation (2.0-33 ng MeHg m(-2) d(-1)), which is a sink for a large proportion of the MeHg produced by Hg(II) methylation in these ponds. We also show that MeHg production in the two study ponds is comparable to what has previously been measured in numerous more southerly systems known to be important MeHg sources, such as temperate wetlands and lakes, demonstrating that wetland ponds in the High Arctic are important sources of MeHg to local aquatic foodwebs. PMID:22779785

  16. Methylmercury biomagnification in an Arctic pelagic food web.

    PubMed

    Ruus, Anders; Øverjordet, Ida B; Braaten, Hans Fredrik V; Evenset, Anita; Christensen, Guttorm; Heimstad, Eldbjørg S; Gabrielsen, Geir W; Borgå, Katrine

    2015-11-01

    Mercury (Hg) is a toxic element that enters the biosphere from natural and anthropogenic sources, and emitted gaseous Hg enters the Arctic from lower latitudes by long-range transport. In aquatic systems, anoxic conditions favor the bacterial transformation of inorganic Hg to methylmercury (MeHg), which has a greater potential for bioaccumulation than inorganic Hg and is the most toxic form of Hg. The main objective of the present study was to quantify the biomagnification of MeHg in a marine pelagic food web, comprising species of zooplankton, fish, and seabirds, from the Kongsfjorden system (Svalbard, Norway), by use of trophic magnification factors. As expected, tissue concentrations of MeHg increased with increasing trophic level in the food web, though at greater rates than observed in several earlier studies, especially at lower latitudes. There was strong correlation between MeHg and total Hg concentrations through the food web as a whole. The concentration of MeHg in kittiwake decreased from May to October, contributing to seasonal differences in trophic magnification factors. The ecology and physiology of the species comprising the food web in question may have a large influence on the magnitude of the biomagnification. A significant linear relationship was also observed between concentrations of selenium and total Hg in birds but not in zooplankton, suggesting the importance of selenium in Hg detoxification for individuals with high Hg concentrations. PMID:26274519

  17. Controls on methylmercury accumulation in northern Gulf of Mexico sediments

    NASA Astrophysics Data System (ADS)

    Liu, Bian; Schaider, Laurel A.; Mason, Robert P.; Shine, James P.; Rabalais, Nancy N.; Senn, David B.

    2015-06-01

    We examined Hg biogeochemistry in northern Gulf of Mexico (nGOM) sediments along a ∼400 km east-west transect off the Louisiana coast in order to characterize primary controls on net methylmercury (MeHg) production and accumulation in sediments and evaluate the potential influence of water column hypoxia. Total Hg (THg) and MeHg concentrations ranged from 52 to 340 pmol g-1 and 0.08 to 1.4 pmol g-1, respectively, and exhibited no clear east-west spatial trends, or trends related to water column hypoxia. Potential methylation and demethylation rate constants (km and kdm), from enriched isotope spikes (201Hg(II) and Me199Hg) to intact sediment cores, were substantially higher (0.02-0.19 d-1 and 39-63 d-1, respectively) than in other coastal sediment systems. The percentage of Hg present as MeHg in sediment cores (%MeHg = 0.04-1.1%) was comparable to other systems. Both %MeHg and km decreased with sediment depth and were significantly correlated, but neither was correlated with organic carbon (OC). Together, OC and km explained 56% of the variation in [MeHg]. These results suggest that OC primarily acts as a MeHg-binding ligand in nGOM sediments, unlike some other coastal systems where OC has been shown to directly influence Hg methylation.

  18. Collaborative study on determination of mono methylmercury in seafood.

    PubMed

    Valdersnes, Stig; Fecher, Peter; Maage, Amund; Julshamn, Kaare

    2016-03-01

    Eight laboratories participated in an inter-laboratory method-performance (collaborative) study of a method for the determination of mono methylmercury (MMHg) in foodstuffs of marine origin by gas chromatography inductively coupled plasma isotope dilution mass spectrometry (GC-ICP-IDMS) after dissolution, derivatisation and extraction of the species. The method was tested on seven seafood products covering both a wide concentration range and variations in the MMHg concentrations as well as matrix compositions. The samples were mussel tissue, squid muscle, crab claw meat, whale meat, cod muscle, Greenland halibut muscle and dogfish liver (NRCC DOLT-4), with MMHg concentrations ranging from 0.035 to 3.58mg/kg (as Hg) dry weight. Repeatability relative standard deviations (RSDr) for MMHg ranged from 2.1% to 8.7%. Reproducibility relative standard deviations (RSDR) ranged from 5.8% to 42%. All samples showed HorRat value below 1.0, except for the sample with the lowest MMHg content, mussel tissue, with a HorRat value of 1.6. PMID:26471575

  19. Methylmercury production in estuarine sediments: role of organic matter

    PubMed Central

    Schartup, Amina T.; Mason, Robert P.; Balcom, Prentiss H.; Hollweg, Terill A.; Chen, Celia Y.

    2013-01-01

    Methylmercury (MeHg) affects wildlife and human health mainly through marine fish consumption. In marine systems, MeHg is formed from inorganic mercury (HgII) species primarily in sediments then accumulates and biomagnifies in the food web. Most of the fish consumed in the US are from estuarine and marine systems highlighting the importance of understanding MeHg formation in these productive regions. Sediment organic matter has been shown to limit mercury methylation in estuarine ecosystems, as a result it is often described as the primary control over MeHg production. In this paper, we explore the role of organic matter by looking at the effects of its changing sediment concentrations on the methylation rates across multiple estuaries. We measured sedimentary MeHg production at eleven estuarine sites that were selected for their contrasting biogeochemical characteristics, mercury (Hg) content, and location in the Northeastern US (ME, NH, CT, NY, and NJ). Sedimentary total Hg concentrations ranged across five orders of magnitude, increasing in concentration from the pristine, sandy sediments of Wells (ME), to industrially contaminated areas like Portsmouth (NH) and Hackensack (NJ). We find that methylation rates are the highest at locations with high Hg content (relative to carbon), and that organic matter does not hinder mercury methylation in estuaries. PMID:23194318

  20. Production and retention of methylmercury in inundated boreal forest soils.

    PubMed

    Rolfhus, Kristofer R; Hurley, James P; Bodaly, Richard A Drew; Perrine, Gregory

    2015-03-17

    The Flooded Uplands Dynamics Experiment (FLUDEX) was an ecosystem-scale study examining the production of methylmercury (MeHg) and greenhouse gases from reservoirs constructed on an upland boreal forest landscape in order to quantify their dependence upon carbon stores. We detail the within-reservoir production and storage of MeHg before, during, and nine years after the experiment. The reservoirs were net MeHg producers during the first two years of flooding, and net demethylating systems afterward. During years 1-3, a rapid pulse of MeHg and total Hg was observed in floodwater, followed by substantial increases in MeHg in seston and sediment. Resampling of the dry reservoirs nine years after the experiment ended indicated that organic soil MeHg was still 8 to 52-fold higher than preflood conditions, and averaged 86% of the levels recorded at the end of the third flooding year. Both total Hg and MeHg retention in soil were a strong function of organic carbon content. The time scale of soil MeHg retention may help explain the decadal time lag frequently observed for the decrease of piscivorous fish Hg concentrations in new reservoirs. Predicted extreme precipitation events associated with climate change may serve to make landscapes more susceptible to this process. PMID:25668143

  1. Flood hydrology and methylmercury availability in Coastal Plain rivers

    USGS Publications Warehouse

    Bradley, Paul M.; Journey, Celeste A.; Chapelle, Francis H.; Lowery, Mark A.; Conrads, Paul A.

    2010-01-01

    Mercury (Hg) burdens in top-predator fish differ substantially between adjacent South Carolina Coastal Plain river basins with similar wetlands coverage. In the Congaree River, floodwaters frequently originate in the Blue Ridge and Piedmont regions, where wetlands coverage and surface water dissolved methylmercury (MeHg) concentrations are low. Piedmont-driven flood events can lead to downward hydraulic gradients in the Coastal Plain riparian wetland margins, inhibiting MeHg transport from wetland sediments, and decreasing MeHg availability in the Congaree River habitat. In the adjacent Edisto River basin, floodwaters originate only within Coastal Plain sediments, maintaining upward hydraulic gradients even during flood events, promoting MeHg transport to the water column, and enhancing MeHg availability in the Edisto River habitat. These results indicate that flood hydrodynamics contribute to the variability in Hg vulnerability between Coastal Plain rivers and that comprehensive regional assessment of the relationship between flood hydrodynamics and Hg risk in Coastal Plain streams is warranted.

  2. Specific immunofluorescence staining of Treponema pallidum in smears and tissues.

    PubMed

    Ito, F; Hunter, E F; George, R W; Swisher, B L; Larsen, S A

    1991-03-01

    To date, tissue sections prepared from Formalin-fixed tissues have not been successfully stained with Treponema pallidum subspecies-specific antibody in a direct fluorescent-antibody assay. While current methods stain T. pallidum, they do not distinguish T. pallidum from other spirochetes such as Borrelia burgdorferi (E. F. Hunter, P. W. Greer, B. L. Swisher, A. R. Simons, C. E. Farshy, J. A. Crawford, and K. R. Sulzer, Arch. Pathol. Lab. Med. 108:878-880, 1984). Because trypsin pretreatment of tissue sections has enhanced other immunofluorescent-antibody (IFA) applications, we compared the use of the trypsin digestion method with the current 1% ammonium hydroxide (NH4OH) method as a means to obtain specific staining of T. pallidum in tissues by both direct and indirect IFA techniques. Pretreated T. pallidum-infected tissues sections from rabbits, hamsters, and humans were quantitatively examined with the direct fluorescent-antibody-T. pallidum test conjugate absorbed with Treponema phagedenis, the Reiter treponeme. For indirect staining, a serum specimen from a patients with syphilis absorbed by affinity chromatography with T. phagedenis was used as the primary reagent, and a fluorescein isothiocyanate-labeled rabbit anti-human globulin was used as the secondary reagent. Serum specificity was established first by examining antigen smears of T. pallidum subsp. pallidum, T. pallidum subsp. pertenue, B. burgdorferi, T. phagedenis, and Treponema denticola MRB and then by examining tissues infected with these pathogens plus those infected with four Leptospira serovars. When we stained tissue using the direct IFA method that is currently a standard method for the examination of chancre smears, we found it to be unsuitable for use with tissue. Trypsin digestion did not offer an improvement over the NH4OH pretreatment method in the specific identification of T. pallidum by direct IFA. However, specific identification of T. pallidum in tissue sections was obtained by the

  3. Dense fine speckled indirect immunofluorescence pattern in an Australian population.

    PubMed

    Broadfoot, Andrew; Sivertsen, Terri; Baumgart, Karl

    2016-04-01

    The dense fine speckled (DFS) pattern is an antinuclear antibody (ANA) pattern that has recently become of interest. This particular pattern has not been associated with systemic autoimmune rheumatic disorders (SARD) but has been associated with other inflammatory conditions such as interstitial nephritis, autoimmune thyroid disease and atopic eczema as well as being found in healthy individuals. We have been reporting this pattern in our laboratory for the past 3 years. The objective of this study was to determine the frequency of the DFS pattern as detected on indirect immunofluorescence (IIF) in an Australian population and to assess association of this pattern with other laboratory autoimmune markers. ANA tests performed by IIF from July 2012 until June 2014 were reviewed and the frequency of DFS pattern was determined. All DFS positive samples that had undergone concurrent testing for antibodies to extractable nuclear antigens (ENA), anti-dsDNA antibodies, rheumatoid factor (RF), anti-citrullinated protein antibodies (CCP) and anti- phospholipid antibodies were compared. Over the 2 year period, 181,819 patients had ANA tests performed and 51,905 were ANA positive. The DFS pattern was found in 5.7% of ANA positive patients. Within this group of patients, only 1.8% were positive for antibodies to ENA and only 0.7% had anti-dsDNA antibodies level greater than 9 IU/mL. RF and anti-CCP antibodies were positive in 6.3% and 4.1% of DFS positive samples, respectively. There were only two samples positive for anti-phospholipid antibodies when the DFS pattern was present. The presence of the DFS pattern as detected by IIF is infrequently associated with autoimmune markers of SARD which is consistent with international studies. PMID:27020500

  4. Percent methylmercury and organic mercury in tissues of marine mammals and fish using different experimental and calculation methods

    SciTech Connect

    Wagemann, R.; Trebacz, E.; Hunt, R.; Boila, G.

    1997-09-01

    Muscle and liver tissues of marine mammals and fish were extracted with methylene chloride-hexane (DCM-hexane) or toluene and the extracts were analyzed for organic mercury by cold vapor atomic absorption spectroscopy (CVAAS) and for methylmercury by gas liquid chromatography with an electron capture detector (GC-ECD). Total mercury in tissues was determined by VCAAS. Methylmercury and organic mercury concentrations in muscle agreed with each other and with total mercury for both marine mammals and fish, indicating that on average 100% of the total mercury in this tissue was in the form of methylmercury. Either total mercury or organic mercury determined by CVAAS was found to be a valid measure of the average methylmercury concentration in muscles of marine mammals and fish. In liver, the CVAAS method produced higher mercury values (15% organic mercury) than the GC-ECD method (6% methylmercury), methylmercury being only 38% of organic mercury. From this, the presence of organic mercury compound(s) other than methylmercury was inferred. The CVAAS method produced a biased estimate of methylmercury in liver; an accurate measure of methylmercury in this tissue was obtained by GC-ECD, either with DCM-hexane or with toluene extraction. The DCM-hexane extract could be directly analyzed by CVAAS for organic mercury while toluene required an additional back-extraction step for such a determination. In calculating the average percentage of methylmercury and organic mercury in a sample, three different calculation methods were used. Only one of them, linear, robust regression analysis produced acceptable results when the variables (MeHg, organic Hg, total Hg) were significantly correlated. The other two methods overestimated the mean percentage under these conditions.

  5. [An immunofluorescent analysis of bovine rotavirus during its isolation and adaptation to cell cultures].

    PubMed

    Skybyts'kyĭ, V H; Nosach, L M; Martynenko, D L; Onufriiev, V P

    1993-01-01

    The results from comparative studies in the reactions of immunofluorescence, complement binding, diffusion precipitation, hemagglutination, solid-phase immunoenzyme analysis, histochemical variant of immunoenzyme analysis as tests for detection of cattle rotavirus in the process of its isolation from pathological material and adaptation to cell cultures are presented. The immunofluorescence reaction is shown to have an advantage over the other reactions. PMID:8388533

  6. Role of hydrosulfide ions (HS-) in methylmercury resistance in Saccharomyces cerevisiae.

    PubMed Central

    Ono, B; Ishii, N; Fujino, S; Aoyama, I

    1991-01-01

    Methylmercury-resistant mutants were obtained from Saccharomyces cerevisiae. They were divided into two complementation groups, met2 (homoserine O-acetyltransferase deficiency) and met15 (enzyme deficiency unknown), as reported previously. It was found that met15 was allelic to met17 (O-acetylserine and O-acetylhomoserine sulfhydrylase deficiency). Methylmercury toxicity was counteracted by exogenously added HS-, and both met2 and met17 (met15) mutants overproduced H2S. On the basis of these results, we conclude that met2 and met17 (met15) cause accumulation of hydrosulfide ions in the cell and that the increased level of hydrosulfide is responsible for detoxification of methylmercury. Images PMID:1781681

  7. Laser light-scattering study of the toxic effects of methylmercury on sperm motility

    SciTech Connect

    Mohamed, M.K.; Lee, W.I.; Mottet, N.K.; Burbacher, T.M.

    1986-01-01

    An in vitro study was designed using the laser light-scattering technique to obtain further information on the dose-effect relationship of methylmercury on sperm motility. The technique provided a quantitative evaluation of sperm swimming speed. Semen samples were collected from normal male Macaca fascicularis monkeys by anal electroejaculation. Methylmercury was added to aliquots of sperm suspensions in BWW medium in doses of 10, 5, 2, and 1 ppm. After 3 hours, the relative speed was 35%, 59%, 69%, and 92% of the corresponding controls at doses of 10, 5, 2, and 1 ppm, respectively. The percentage of motile spermatozoa decreased significantly at 10 ppm. By microscopic observation abnormal motility was detected at 5 and 10 ppm, especially after 20 to 40 minutes. Head movement increased from side to side, and many spermatozoa developed coiled tails. The technique proved useful for defining the dose-effect relationship of methylmercury and sperm swimming speed.

  8. A regional mass balance of methylmercury in San Francisco Bay, California, USA.

    PubMed

    Yee, Donald; McKee, Lester J; Oram, John J

    2011-01-01

    The San Francisco Bay (California, USA) is a water body listed as impaired because of Hg contamination in sport fish for human consumption, as well as possible effects on resident wildlife. A legacy of Hg mining in local watersheds and Hg used in Au mining in the Sierra Nevada (USA) has contributed to contamination seen in the bay, with additional more recent and ongoing inputs from various sources. Methylmercury is the species of Hg most directly responsible for contamination in biota, so better understanding of its sources, loads, and processes was sought to identify the best means to reduce impacts. A regional scale model of San Francisco Bay was developed to characterize major methylmercury inputs and processes. The model was used to evaluate the potential impact of uncertainties in estimates for methylmercury loading pathways and environmental processes, identify major data gaps, and explore management prospects for reducing methylmercury contamination. External loading pathways considered in the mass balance include methylmercury loads entering via atmospheric deposition to the bay surface, and discharges from the Sacramento/San Joaquin Delta, local watersheds, municipal wastewater, and fringing wetlands. Internal processes considered include exchange between bed and suspended sediments and the water column, in situ production and demethylation, biological uptake, and losses via hydrologic transport to the ocean through the Golden Gate. In situ sediment methylation and demethylation were dominant sources and losses determining ambient steady-state concentrations in the model, with changes in external loads and export causing smaller changes. Better information on methylation and demethylation is thus most critical to improving understanding of methylmercury balances and management. PMID:20872899

  9. [Comparative study of indirect immunofluorescence (IIF) and ELISA techniques in the detection of parvovirus B19].

    PubMed

    González, M; Hassanhi, M; Rivera, S; Bracho, M P

    2000-03-01

    To determine the seroprevalence of IgG and IgM antibodies against Parvovirus B19 (P. B19), we studied the sera of 53 patients with different hematologic disorders and the sera of 15 controls using indirect immunofluorescence (IFI) and the ELISA method. The prevalence of IgG in the control group was 46.6%, in patients with aplastic crisis was 83.3% (IFI) and 66.7% (ELISA) and, in patients without crisis was 68.9% (IFI) and 72.4% (ELISA). IgM was negative except for patients with crisis: 8.3% (IFI) and 29.1% (ELISA). The higher seroprevalence (IgG) found in patients in comparison with controls might be due to a greater exposure of of patients to the virus. The agreement for both techniques was 81%(IgG) and 93% (IgM) however ELISA technique was more sensitive for detecting IgM of P. B19. In spite of serologic evidence and evaluating a simple serum sample per patient, we could establish an association between aplastic crisis and viral infection for IgM ELISA but not for IgG between hematologic disorders and infection for the P. B19. PMID:10758696

  10. An Immunofluorescent Method for Characterization of Barrett’s Esophagus Cells

    PubMed Central

    Inge, Landon J.; Fowler, Aaron J.; Bremner, Ross M.

    2014-01-01

    Esophageal adenocarcinoma (EAC) has an overall survival rate of less than 17% and incidence of EAC has risen dramatically over the past two decades. One of the primary risk factors of EAC is Barrett’s esophagus (BE), a metaplastic change of the normal squamous esophagus in response to chronic heartburn. Despite the well-established connection between EAC and BE, interrogation of the molecular events, particularly altered signaling pathways involving progression of BE to EAC, are poorly understood. Much of this is due to the lack of suitable in vitro models available to study these diseases. Recently, immortalized BE cell lines have become commercially available allowing for in vitro studies of BE. Here, we present a method for immunofluorescent staining of immortalized BE cell lines, allowing in vitro characterization of cell signaling and structure after exposure to therapeutic compounds. Application of these techniques will help develop insight into the mechanisms involved in BE to EAC progression and provide potential avenues for treatment and prevention of EAC. PMID:25079877

  11. Automated Image Analysis for Determination of Antibody Titers Against Occupational Bacterial Antigens Using Indirect Immunofluorescence.

    PubMed

    Brauner, Paul; Jäckel, Udo

    2016-06-01

    Employees who are exposed to high concentrations of microorganisms in bioaerosols frequently suffer from respiratory disorders. However, etiology and in particular potential roles of microorganisms in pathogenesis still need to be elucidated. Thus, determination of employees' antibody titers against specific occupational microbial antigens may lead to identification of potentially harmful species. Since indirect immunofluorescence (IIF) is easy to implement, we used this technique to analyze immunoreactions in human sera. In order to address disadvantageous inter-observer variations as well as the absence of quantifiable fluorescence data in conventional titer determination by eye, we specifically developed a software tool for automated image analysis. The 'Fluorolyzer' software is able to reliably quantify fluorescence intensities of antibody-bound bacterial cells on digital images. Subsequently, fluorescence values of single cells have been used to calculate non-discrete IgG titers. We tested this approach on multiple bacterial workplace isolates and determined titers in sera from 20 volunteers. Furthermore, we compared image-based results with the conventional manual readout and found significant correlation as well as statistically confirmed reproducibility. In conclusion, we successfully employed 'Fluorolyzer' for determination of titers against various bacterial species and demonstrated its applicability as a useful tool for reliable and efficient analysis of immune response toward occupational exposure to bioaerosols. PMID:27026659

  12. Delayed effects of methylmercury on the mitochondria of dopaminergic neurons and developmental toxicity in zebrafish larvae (Danio rerio).

    PubMed

    Huang, Susie S Y; Noble, Sandra; Godoy, Rafael; Ekker, Marc; Chan, Hing Man

    2016-06-01

    Methylmercury (MeHg) is a known neurotoxicant affecting the central nervous system but effects on dopaminergic (DA) neurons are not well understood. Wild-type zebrafish (Danio rerio) and two transgenic lines: Tg(dat:eGFP) expressing enhanced green fluorescent protein (eGFP) in DA neuron clusters and Tg(dat:tom20 MLS-mCherry) expressing red fluorescence (mCherry) targeted to mitochondria of DA neurons were used to evaluate the effects of micromolar MeHg exposure on DA neuron and whole animal motor function during early development. Three-day-old larvae were exposed to micromolar concentrations of MeHg (0.03, 0.06, and 0.3μM) in system water. Exposure to 0.3μM MeHg caused mortality and significant morphological abnormalities including edema, curvature of the spine, and hemorrhages in zebrafish larvae after a 48h exposure period. At 0.06μM MeHg, the appearance of morphological abnormalities was delayed for 72h and far less severe, whereas 0.03μM MeHg did not cause any morphological defects or mortalities. A delayed but significant reduction in locomotor ability and mCherry fluorescence in specific brain regions in the 0.06μM MeHg exposed larvae suggests that DA neuron function rather than neuron numbers was compromised. Double immunolabeling with tyrosine hydroxylase and pan neural staining showed no effect of MeHg exposure. We have established Tg(dat:tom20 MLS-mCherry) zebrafish larvae as a model which can be used to assess MeHg neurotoxicity and that exposure to low dose MeHg (0.06μM) during development may predispose DA neurons to impairment caused by changes in mitochondrial dynamics. PMID:26994370

  13. Methylmercury distribution in the Upper Part of the Southern Ocean Water Column

    NASA Astrophysics Data System (ADS)

    Cossa, D.; Butler, E.; Heimbuerger, L.; Averty, B.; Bowie, A.; Watson, R.; Remenyi, T.

    2008-12-01

    Methylmercury has been determined in 93 sea water samples from the first thousand meters on 10 stations between Tasmania and Terre-Adelie in the Southern Ocean (SR3 Geotraces transect). Concentrations varied wildly from <15 to 858 fM, with a mean concentration of 272 fM and a standard deviation of 212 fM. The vertical distributions exhibited systematic nutrient like profiles. Highest methylmercury concentrations were found in the high productive region near the Antarctica divergence zone and the lowest in and quite unproductive pool of water north of the Subantarctic Front structure.

  14. Methylmercury photodegradation in surface water of the Florida Everglades: importance of dissolved organic matter-methylmercury complexation.

    PubMed

    Tai, Chao; Li, Yanbin; Yin, Yongguang; Scinto, Leonard J; Jiang, Guibin; Cai, Yong

    2014-07-01

    Photodegradation is the major pathway of methylmercury (MeHg) degradation in many surface waters. However, the mechanism of MeHg photodegradation is still not completely understood. Dissolved organic matter (DOM) is expected to play a critical role in MeHg photodegradation. By using several techniques, including N2/O2 purging and the addition of stable isotope (Me(201)Hg), scavengers, competing ligands, and a singlet oxygen ((1)O2) generator, the role played by MeHg-DOM complexation in MeHg photodegradation of Everglades surface water was investigated. DOM appeared to be involved in MeHg photodegradation via the formation MeHg-DOM complexes based on three findings: (1) MeHg was quickly photodegraded in solutions containing DOM extracts; (2) degradation of MeHg did not occur in deionized water; and (3) addition of competing complexation reagents (dithiothreitol-DTT) dramatically prohibited the photodegradation of MeHg in Everglades water. Further experiments indicated that free radicals/reactive oxygen species, including hydroxyl radical (·OH), (1)O2, triplet excited state of DOM ((3)DOM*), and hydrated electron (e(-)aq), played a minor role in MeHg photodegradation in Everglades water, based on the results of scavenger addition, (1)O2 generator addition and N2/O2 purging. A pathway, involving direct photodegradation of MeHg-DOM complexes via intramolecular electron transfer, is proposed as the dominant mechanism for MeHg photodegradation in Everglades water. PMID:24901379

  15. Methylmercury Concentration in Fish and Risk-Benefit Assessment of Fish Intake among Pregnant versus Infertile Women in Taiwan.

    PubMed

    Hsi, Hsing-Cheng; Hsu, You-Wen; Chang, Tien-Chin; Chien, Ling-Chu

    2016-01-01

    This study examined methylmercury (MeHg) concentrations in fish, the daily MeHg exposure dose, and the risk-benefit of MeHg, ω-3 polyunsaturated fatty acid (ω-3 PUFA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) related to fish intake among pregnant and infertile women in Taiwan. The measured MeHg concentrations in fish did not exceed the Codex guideline level of 1 mg/kg. Swordfish (0.28 ± 0.23 mg/kg) and tuna (0.14 ± 0.13 mg/kg) had the highest MeHg concentrations. The MeHg concentration in the hair of infertile women (1.82 ± 0.14 mg/kg) was significantly greater than that of pregnant women (1.24 ± 0.18 mg/kg). In addition, 80% of infertile women and 68% of pregnant women had MeHg concentrations in hair that exceeded the USEPA reference dose (1 mg/kg). The MeHg concentrations in hair were significantly and positively correlated with the estimated daily MeHg exposure dose. Based on the risk-benefit evaluation results, this paper recommends consumption of fish species with a low MeHg concentration and high concentrations of DHA + EPA and ω-3 PUFA (e.g., salmon, mackerel, and greater amberjack). PMID:27187161

  16. The putative multidrug resistance protein MRP-7 inhibits methylmercury-associated animal toxicity and dopaminergic neurodegeneration in Caenorhabditis elegans.

    PubMed

    VanDuyn, Natalia; Nass, Richard

    2014-03-01

    Parkinson's disease (PD) is the most prevalent neurodegenerative motor disorder worldwide, and results in the progressive loss of dopamine (DA) neurons in the substantia nigra pars compacta. Gene-environment interactions are believed to play a significant role in the vast majority of PD cases, yet the toxicants and the associated genes involved in the neuropathology are largely ill-defined. Recent epidemiological and biochemical evidence suggests that methylmercury (MeHg) may be an environmental toxicant that contributes to the development of PD. Here, we report that a gene coding for the putative multidrug resistance protein MRP-7 in Caenorhabditis elegans modulates whole animal and DA neuron sensitivity to MeHg. In this study, we demonstrate that genetic knockdown of MRP-7 results in a twofold increase in Hg levels and a dramatic increase in stress response proteins associated with the endoplasmic reticulum, golgi apparatus, and mitochondria, as well as an increase in MeHg-associated animal death. Chronic exposure to low concentrations of MeHg induces MRP-7 gene expression, while exposures in MRP-7 genetic knockdown animals results in a loss of DA neuron integrity without affecting whole animal viability. Furthermore, transgenic animals expressing a fluorescent reporter behind the endogenous MRP-7 promoter indicate that the transporter is expressed in DA neurons. These studies show for the first time that a multidrug resistance protein is expressed in DA neurons, and its expression inhibits MeHg-associated DA neuron pathology. PMID:24266639

  17. Methylmercury Concentration in Fish and Risk-Benefit Assessment of Fish Intake among Pregnant versus Infertile Women in Taiwan

    PubMed Central

    Hsi, Hsing-Cheng; Hsu, You-Wen; Chang, Tien-Chin; Chien, Ling-Chu

    2016-01-01

    This study examined methylmercury (MeHg) concentrations in fish, the daily MeHg exposure dose, and the risk–benefit of MeHg, ω-3 polyunsaturated fatty acid (ω-3 PUFA), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA) related to fish intake among pregnant and infertile women in Taiwan. The measured MeHg concentrations in fish did not exceed the Codex guideline level of 1 mg/kg. Swordfish (0.28 ± 0.23 mg/kg) and tuna (0.14 ± 0.13 mg/kg) had the highest MeHg concentrations. The MeHg concentration in the hair of infertile women (1.82 ± 0.14 mg/kg) was significantly greater than that of pregnant women (1.24 ± 0.18 mg/kg). In addition, 80% of infertile women and 68% of pregnant women had MeHg concentrations in hair that exceeded the USEPA reference dose (1 mg/kg). The MeHg concentrations in hair were significantly and positively correlated with the estimated daily MeHg exposure dose. Based on the risk–benefit evaluation results, this paper recommends consumption of fish species with a low MeHg concentration and high concentrations of DHA + EPA and ω-3 PUFA (e.g., salmon, mackerel, and greater amberjack). PMID:27187161

  18. Sources of Mercury Exposure for U.S. Seafood Consumers: Implications for Policy

    EPA Science Inventory

    Recent policies attempting to reduce adverse effects of methylmercury exposure from fish consumption in the U.S. have targeted reductions in anthropogenic emissions from U.S. sources. Methods: We use models that simulate global atmospheric chemistry (GEOS-Chem); the fate, transp...

  19. Bacterial methylmercury degradation in Florida Everglades peat sediment

    USGS Publications Warehouse

    Marvin-DiPasquale, M. C.; Oremland, R.S.

    1998-01-01

    Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying 14CH4 and 14CO2 production after incubation of anaerobic sediments with [14C]MeHg. Degradation rate constants (k) were consistently ???0.1 d-1 and decreased with sediment depth. Higher k values were observed when shorter incubation times and lower MeHg amendment levels were used, and k increased 2-fold as in-situ MeHg concentrations were approached. The average floc layer k was 0.046 ?? 0.023 d-1 (n = 17) for 1-2 day incubations. In-situ degradation rates were estimated to be 0.02-0.5 ng of MeHg (g of dry sediment)-1 d-1, increasing from eutrophied to pristine areas. Nitrate-respiring bacteria did not demethylate MeHg, and NO3- addition partially inhibited degradation in some cases. MeHg degradation rates were not affected by PO43- addition. 14CO2 production in all samples indicated that oxidative demethylation (OD) was an important degradation mechanism. OD occurred over 5 orders of magnitude of applied MeHg concentration, with lowest limits [1-18 ng of MeHg (g of dry sediment)-1] in the range of in-situ MeHg levels. Sulfate reducers and methanogens were the primary agents of anaerobic OD, although it is suggested that methanogens dominate degradation at in-situ MeHg concentrations. Specific pathways of OD by these two microbial groups are proposed.Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying 14CH4 and 14CO2 production after incubation of anaerobic sediments with [14C]MeHg. Degradation rate constants (k) were consistently ???0.1 d-1 and decreased with sediment depth. Higher k values were observed when shorter incubation times and lower MeHg amendment levels were used, and k increased 2-fold as in-situ MeHg concentrations were approached. The average floc layer k was 0.046??0.023 d-1 (n = 17) for 1-2 day incubations. In-situ degradation rates were estimated to be 0

  20. Total Mercury and Methylmercury Dynamics; stream export in an upland forested watershed in the Adirondack region of New York State

    NASA Astrophysics Data System (ADS)

    Carleton, W.; Vidon, P.; Mitchell, M. J.

    2012-12-01

    Although levels of mercury and acid rain deposition have greatly declined in recent years due to legislation controls on industry emissions, their legacy has had a lasting effect on the Adirondack region of New York State. This historical mercury deposition is of concern because of the high chance for methylmercury production and export to occur. The impact of forested uplands on methylmercury export remains poorly understood in relation to other ecosystems. Research indicates that sulfate dynamics play a large role in regulating the production of methylmercury in the presence of inorganic mercury; however the relationship between methylmercury production and nitrate availability at various times of the year is less understood, yet, hypothesized to potentially impact sulfate reduction and ultimately methylmercury production in a variety of ecosystems. In this study, mercury and water quality (including sulfate and nitrate) will be monitored in spring, summer and fall of 2012 at 7 locations in Arbutus Watershed, Adirondacks, NY. Proxies (UV absorbance, Fluorescence indices) for total mercury and methylmercury will be utilized to predict export. The main objectives of this research are to determine the relevance of forested uplands in methylmercury export, as well as gain further understanding of mercury dynamics and associated proxies in relation to nitrate and sulfate availability. Photo courtesy of the Adirondack Ecological Center

  1. Methylmercury production in a Chesapeake Bay salt marsh

    NASA Astrophysics Data System (ADS)

    Mitchell, Carl P. J.; Gilmour, Cynthia C.

    2008-06-01

    In a detailed study of the biogeochemical factors affecting the methylation of mercury in a Chesapeake Bay salt marsh, we examined relationships between mercury methylation and numerous variables, including sulfate reduction rates, organic carbon mineralization rates, iron and sulfur chemistry, and the character of dissolved organic matter (DOM). Our data show that salt marshes are important sites of de novo methylmercury (MeHg) production in coastal ecosystems. Some of the controls on MeHg production that have been well-described in other ecosystems also impacted MeHg production in this salt marsh, specifically the effect of sulfide accumulation on mercury bioavailability. We observed some novel biogeochemical relationships with Hg(II)-methylation and MeHg accumulation, particularly the positive association of Hg(II)-methylation with zones of microbial iron reduction. On the basis of this relationship, we suggest caution in wetland and groundwater remediation approaches involving iron additions. Aqueous phase Hg complexation appeared to be the dominant control on Hg bioavailability across the marsh sites examined, rather than Hg partitioning behavior. A detailed examination of DOM character in the marsh suggested a strong positive association between Hg(II)-methylation rate constants and increasing DOM molecular weight. Overall, our results indicate that net MeHg production is controlled by a balance between microbial activity and geochemical effects on mercury bioavailability, but that a significant zone of MeHg production can persist in near surface salt marsh soils. Production of MeHg in coastal marshes may negatively impact ecosystems via export to adjacent estuaries or through direct bioaccumulation in birds, fish and amphibians that feed in these highly productive ecosystems.

  2. Bacterial methylmercury degradation in Florida Everglades peat sediment

    SciTech Connect

    Marvin-Dipasquale, M.C.; Oremland, R.S.

    1998-09-01

    Methylmercury (MeHg) degradation was investigated along an eutrophication gradient in the Florida Everglades by quantifying {sup 14}CH{sub 4} and {sup 14}CO{sub 2} production after incubation of anaerobic sediments with [{sup 14}C]MeHg. Degradation rate constants (k) were consistently {le}0.1 d{sup {minus}1} and decreased with sediment depth. Higher k values were observed when shorter incubation times and lower MeHg amendment levels were used, and k increased 2-fold as in-situ MeHg concentrations were approached. The average floc layer k was 0.046 {+-} 0.023 d{sup {minus}1} (n = 17) for 1--2 day incubations. In-situ degradation rates were estimated to be 0.02--0.5 ng of MeHg (g of dry sediment){sup {minus}1} d{sup {minus}1}, increasing from eutrophied to pristine areas. Nitrate-respiring bacteria did not demethylate MeHg, and NO{sub 3}{sup {minus}} addition partially inhibited degradation in some cases. MeHg degradation rates were not affected by PO{sub 4}{sup 3{minus}} addition. {sup 14}CO{sub 2} production in all samples indicated that oxidative demethylation (OD) was an important degradation mechanism. OD occurred over 5 orders of magnitude of applied MeHg concentration, with lowest limits in the range of in-situ MeHg levels. Sulfate reducers and methanogens were the primary agents of anaerobic OD, although it is suggested that methanogens dominate degradation at in-situ MeHg concentrations. Specific pathways of OD by these two microbial groups are proposed.

  3. Influence of nutrient level on methylmercury content in water spinach.

    PubMed

    Greger, Maria; Dabrowska, Beata

    2010-08-01

    Widely consumed vegetables are often cultivated in sewage waters with high nutrient levels. They can contain high levels of methylmercury (MeHg), because they can form MeHg from inorganic Hg in their young shoots. We determined whether the MeHg uptake and the MeHg formation in the shoots of water spinach (Ipomoea aquatica) were affected by the presence of a high nutrient level in the growth medium. Water spinach shoots were rooted and pretreated in growth medium containing 7% (low) or 70% (high) Hoagland nutrient solution; thereafter, the plants were treated with either 0.02 microM MeHg or 0.2 microM HgCl2 for 3 d. Half the plants were then analyzed for total Hg and MeHg. The remaining plants were transferred to mercury-free medium with low or high nutrient levels and posttreated for 3 days before analysis of total Hg and MeHg in order to measure MeHg formation in the absence of external Hg. The results indicate that nutrient level did not influence MeHg uptake, but that a high nutrient level reduced the distribution of MeHg to the shoots 2.7-fold versus low nutrient level. After treatment with HgCl2, MeHg was found in roots and new shoots but not in old shoots. The MeHg:total-Hg ratio was higher in new shoots than in roots, being 13 times higher at high versus low nutrient levels. Thus, MeHg formation was the same in new shoots independent of inorganic Hg concentration, since the total Hg level decreased at a high nutrient level. PMID:20821626

  4. Effects of methylmercury on reproduction in American kestrels

    USGS Publications Warehouse

    Albers, P.H.; Koterba, M.T.; Rossmann, R.; Link, W.A.; French, J.B.; Bennett, R.S.; Bauer, W.C.

    2007-01-01

    Sixty breeding pairs of captive American kestrels (Falco sparverius) were exposed to a range of sublethal dietary concentrations of mercury (Hg), in the form of methylmercuric chloride, and their subsequent reproduction was measured. Egg production, incubation performance, and the number and percent of eggs hatched decreased markedly between 3.3 and 4.6 mg/kg dry weight of Hg (1.2 and 1.7 mg/kg wet wt), in the diet. The number of fledglings and the percent of nestlings fledged were reduced markedly at 0.7 mg/kg dry weight (0.3 mg/kg wet wt) and declined further between 2 and 3.3 mg/kg dry weight (0.7 and 1.2 mg/kg wet wt). Dietary concentrations of ?4.6 mg/kg dry weight (1.7 mg/kg wet wt) were associated with total fledging failure. The estimated decline in fledged young per pair (24%, Bayesian regression) for kestrels consuming 0.7 mg/kg dry weight (0.3 mg/ kg wet wt) raises concerns about population maintenance in areas subject to high inputs of anthropogenic Hg. Mercury concentrations in 20 second-laid eggs collected from all groups were related to dietary concentrations of Hg, and the Hg concentrations in 19 of these eggs were related to eggs laid and young fledged. Concentrations of Hg in eggs from the highest diet group (5.9 mg/kg dry wt; 2.2 mg/kg wet wt) were higher than egg concentrations reported for either wild birds or for captive birds (nonraptors) fed dry commercial food containing 5 mg/kg methylmercury. Accumulation ratios of Hg from diets to eggs were higher than those reported for feeding studies with other species.

  5. Sulfate threshold target to control methylmercury levels in wetland ecosystems

    USGS Publications Warehouse

    Corrales, J.; Naja, G.M.; Dziuba, C.; Rivero, R.G.; Orem, W.

    2011-01-01

    Sulfate contamination has a significant environmental implication through the stimulation of toxic hydrogen sulfide and methylmercury (MeHg) production. High levels of MeHg are a serious problem in many wetland ecosystems worldwide. In the Florida Everglades, it has been demonstrated that increasing MeHg occurrence is due to a sulfate contamination problem. A promising strategy of lowering the MeHg occurrence is to reduce the amount of sulfate entering the ecosystem. High surface water sulfate concentrations in the Everglades are mainly due to discharges from the Everglades Agricultural Area (EAA) canals. Water and total sulfur mass balances indicated that total sulfur released by soil oxidation, Lake Okeechobee and agricultural application were the major sources contributing 49,169, 35,217 and 11,775mtonsyear-1, respectively. Total sulfur loads from groundwater, levees, and atmospheric deposition contributed to a lesser extent: 4055; 5858 and 4229mtonsyear-1, respectively. Total sulfur leaving the EAA into Water Conservation Areas (WCAs) through canal discharge was estimated at 116,360mtonsyear-1, and total sulfur removed by sugarcane harvest accounted for 23,182mtonsyear-1. Furthermore, a rise in the mineral content and pH of the EAA soil over time, suggested that the current rates of sulfur application would increase as the buffer capacity of the soil increases. Therefore, a site specific numeric criterion for sulfate of 1mgL-1 was recommended for the protection of the Everglades; above this level, mercury methylation is enhanced. In parallel, sulfide concentrations in the EAA exceeded the 2??gL-1 criterion for surface water already established by the U.S. Environmental Protection Agency (EPA). ?? 2011 Elsevier B.V.

  6. Sex-Dependent and Non-Monotonic Enhancement and Unmasking of Methylmercury Neurotoxicity by Prenatal Stress

    PubMed Central

    Weston, Hiromi I.; Sobolewski, Marissa; Allen, Joshua L.; Weston, Doug; Conrad, Katherine; Pelkowski, Sean; Watson, Gene E.; Zareba, Grazyna; Cory-Slechta, Deborah A.

    2014-01-01

    Methylmercury (MeHg) and prenatal stress (PS) are risk factors for neurotoxicity that may co-occur in human populations. Because they also share biological substrates and can produce common behavioral deficits, this study examined their joint effects on behavioral and neurochemical effects in male and female rats. Dams had access to 0, 0.5 or 2.5ppm MeHg chloride drinking water from two weeks prior to breeding through weaning. Half of the dams in each of these treatment groups also underwent PS on gestational days 16–17. This yielded 6 groups/gender: 0-NS, 0-PS, 0.5-NS, 0.5-PS, 2.5-NS, and 2.5-PS. Behavioral testing began in young adulthood and included Fixed Interval (FI) schedule-controlled behavior, novel object recognition (NOR) and locomotor activity, behaviors previously demonstrated to be sensitive to MeHg and/or mediated by brain mesocorticolimbic dopamine glutamate systems targeted by both MeHg and PS. Behavioral deficits were more pronounced in females and included impaired NOR recognition memory only under conditions of combined MeHg and PS, while non-monotonic reductions in FI response rates occurred, with greatest effects at the 0.5ppm concentration; the less reduced 2.5ppm FI response rates were further reduced under conditions of PS (2.5-PS). Correspondingly, many neurochemical changes produced by MeHg were only seen under conditions of PS, particularly in striatum in males and in hippocampus and nucleus accumbens in females, regions of significance to the mediation of FI and NOR performance. Collectively these findings demonstrate sex-dependent and non-monotonic effects of developmental MeHg exposure that can be unmasked or enhanced by PS, particularly for behavioral outcomes in females but for both sexes in neurochemical changes, that were observed at MeHg exposure concentrations that did not influence either reproductive outcomes or maternal behavior. Thus, assessment of risks associated with MeHg may be underestimated in the absence of other

  7. Neurotoxicological effects of low-dose methylmercury and mercuric chloride in developing offspring mice.

    PubMed

    Huang, Chun-Fa; Liu, Shing-Hwa; Hsu, Chuan-Jen; Lin-Shiau, Shoei-Yn

    2011-03-25

    Mercury is a well-known toxic metal and potently induces severe neurotoxicological effects, especially in infants and children. The purpose of this study was to explore the underlying mechanisms of neurotoxic effects of mercurial compounds on the different stages of developing mice. Low-doses (the probability of human exposure in mercury-contaminated areas) of methylmercury (MeHg) (M, 0.02mg/kg/day) and mercury chloride (HgCl(2)) (H, 0.5mg/kg/day) were administered to mice of the following groups: (1) treatment with distilled water for 7 consecutive weeks after weaning (control-vehicle (CV)); exposure to mercurial compounds at different stages; (2) for 7 consecutive weeks after weaning (control-MeHg (CM) and control-HgCl(2) (CH)); (3) only during perinatal and weaning stages (MeHg-vehicle (MV) and HgCl-vehicle (HV)); and (4) in all experimental stages (MeHg-MeHg (MM) and HgCl(2)-HgCl(2) (HH)). Results revealed the neurobehavioral defects (increased locomotor activities, motor equilibrium impairment, and auditory dysfunction) that correlated with increasing Hg accumulation in CM and CH groups. However, it revealed a decrease and an increase in locomotor activities in MV and HV groups, respectively; these became more severe in MM and HH groups than in MV and HV groups. Motor equilibrium performance in MV and HV groups remained normal, while that in MM and HH groups was decreased. The most severe auditory defects (altered auditory brainstem response, ABR test) found in MM and HH groups than those in the respective CM and CH, MV and HV, including absolute wave III delays and interwave I-III latencies, which suggested that the irreversible auditory dysfunction caused by mercurial compounds. Furthermore, the alteration of lipid peroxidation (LPO), Na(+)/K(+)-ATPase activities, and nitric oxide (NO(x)) in the brain tissues contributed to the observed neurobehavioral dysfunction and hearing impairment. These findings provide evidence that fetuses were much more susceptible

  8. ACCUMULATION OF METHYLMERCURY OR POLYCHLORINATED BIPHENYLS IN IN VITRO MODELS OF RAT NEURONAL TISSUE.

    EPA Science Inventory

    This manuscript reports data examining the accumulation of PCBs or methylmercury into the tissue of three commonly used in vitro neuronal models.

    ? The results demonstrate that these lipophilic compounds can accumulate to levels 5 to 100 fold higher than the surrounding s...

  9. BIOCHEMICAL AND FUNCTIONAL ALTERATIONS IN RENAL AND CARDIAC DEVELOPMENT RESULTING FROM NEONATAL METHYLMERCURY TREATMENT

    EPA Science Inventory

    Administration of methylmercury (1 or 2.5 mg/kg daily) to neonatal rats caused alterations in both cardiac and renal growth patterns. Heart weights were elevated in the preweaning period in association with hyperplasia (supranormal DNA content); after weaning, the cardiac overgro...

  10. Phytoremediation Of Mercury And Methylmercury Contaminated Sediments By Water Hyacinth (Eichhornia crassipes)

    EPA Science Inventory

    Phytoremediation has potential to be implemented at mercury (Hg) and methylmercury (MeHg) contaminated sites. Water hyacinths (Eichhornia crassipes) were investigated for their ability to assimilate Hg and MeHg into plant biomass, in both aquatic and sediment-associated f...

  11. Distribution and characteristics of methylmercury in surface sediment in Minamata Bay.

    PubMed

    Matsuyama, Akito; Yano, Shinichiro; Hisano, Akihiro; Kindaichi, Michiaki; Sonoda, Ikuko; Tada, Akihide; Akagi, Hirokatsu

    2016-08-15

    This study was carried out to evaluate the present-day chemical properties of methylmercury in surface sediment in Minamata Bay where a dredging project was completed 28years ago. Present-day sediment from Minamata Bay consists of sandy silt, and the average loss-on-ignition in surface sediment was 7.0±2.3%. The average methylmercury concentrations in the upper sediment layers were significantly higher than those in the lower sediment layers. Currently, the concentrations in sediments in Minamata Bay do not exceed the Japanese regulatory standard value for mercury. The average concentration of methylmercury in Minamata Bay surface sediment was 1.74±1.0ng/g on a dry weight basis (n=107). The methylmercury concentration in Minamata Bay surface sediment was almost 16 times higher than that in surface sediment from Isahaya Bay surface sediment, which was 0.11±0.045ng/g on a dry weight basis (n=5). PMID:27237039

  12. Total mercury, methylmercury and ethylmercury in marine fish and marine fishery products sold in Seoul, Korea.

    PubMed

    Park, Ju-Sung; Jung, So-Young; Son, Yeo-Joon; Choi, Su-Jeong; Kim, Mi-Sun; Kim, Jeong-Gon; Park, So-Hyun; Lee, Sang-Me; Chae, Young-Zoo; Kim, Min-Young

    2011-01-01

    In 2009, a survey of 177 samples of fish and fishery products from the markets in Seoul was carried out to investigate total mercury and organic mercury (methylmercury) concentrations and to establish a correlation, if any, between total and organic mercury levels. Concentrations of total and organic mercury in canned tuna ranged 0.001-2.581 and 0.003-1.307 mg/kg, respectively; those for fish, such as cod or salmon, ranged 0.012-2.529 and 0.021-0.507 mg/kg, respectively. Ethylmercury was not detected. More than 50% of total mercury in the samples existed as organic mercury. The correlation coefficients (r(2)) between total mercury and methylmercury concentrations of fish and fishery products found to have methylmercury were 0.844 and 0.976, respectively, which was statistically significant. There was a higher correlation in fishery products than in fish. Although there was no product in which mercury exceeded the standard set by the Food Code in 2008, with the exception of marlin steak, a processed food, which contained 1.307 mg/kg methylmercury. None exceeded the provisional tolerable weekly intake (PTWI) for mercury. Collectively, the results indicate that fish or fishery products marketed in Seoul, with the exception of marlin, have low levels of total or organic mercury and, thus, intake of these products is not a risk to public health. PMID:24786250

  13. Differential effects of methylmercury, thiols, and vitamins on galactosidases of nervous and non-nervous tissues

    SciTech Connect

    Vijayalakshmi, K.; Bapu, C.; Sood, P.P.

    1992-07-01

    A rational pharmacological attack on heavy metal poisoning has only been possible with the advent of non-toxic binding of chelating agents. In the recent past, a number of chelators have been used to detoxicate the mercury content from the body. When all the well known chelators were subjected for their therapeutic capacities in the central nervous system, most of the findings were discouraging. In a recent study we have demonstrated the superiority of vitamins over thiol compounds in methylmercury mobilization, which otherwise has been considered difficult and often an impossible task for clinicians as well as toxicologists. Biochemical lesions are considered to be the most primary effects of methylmercury toxication, and lysosomes are the critical cellular organelles which are easily ruptured and release enzymes. In the present study, the biochemical analyses of two lysosomal enzymes (alpha and beta-galactosidases) in various nervous and non-nervous tissues of mice during methylmercury toxication as well as detoxication with vitamins and thiols have been studied in the light of previous investigation related to methylmercury mobilization with these agents. 11 refs., 2 figs.

  14. The fatty acid profile of rainbow trout liver cells modulates their tolerance to methylmercury and cadmium.

    PubMed

    Ferain, Aline; Bonnineau, Chloé; Neefs, Ineke; Rees, Jean François; Larondelle, Yvan; Schamphelaere, Karel A C De; Debier, Cathy

    2016-08-01

    The polyunsaturated fatty acid (PUFA) composition of fish tissues, which generally reflects that of the diet, affects various cellular properties such as membrane structure and fluidity, energy metabolism and susceptibility to oxidative stress. Since these cellular parameters can play an important role in the cellular response to organic and inorganic pollutants, a variation of the PUFA supply might modify the toxicity induced by such xenobiotics. In this work, we investigated whether the cellular fatty acid profile has an impact on the in vitro cell sensitivity to two environmental pollutants: methylmercury and cadmium. Firstly, the fatty acid composition of the rainbow trout liver cell line RTL-W1 was modified by enriching the growth medium with either alpha-linolenic acid (ALA, 18:3n-3), eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), linoleic acid (LA, 18:2n-6), arachidonic acid (AA, 20:4n-6) or docosapentaenoic acid (DPA, 22:5n-6). These modified cells and their control (no PUFA enrichment) were then challenged for 24h with increasing concentrations of methylmercury or cadmium. We observed that (i) the phospholipid composition of the RTL-W1 cells was profoundly modulated by changing the PUFA content of the growth medium: major modifications were a high incorporation of the supplemented PUFA in the cellular phospholipids, the appearance of direct elongation and desaturation metabolites in the cellular phospholipids as well as a change in the gross phospholipid composition (PUFA and monounsaturated fatty acid (MUFA) levels and n-3/n-6 ratio); (ii) ALA, EPA and DPA enrichment significantly protected the RTL-W1 cells against both methylmercury and cadmium; (iv) DHA enrichment significantly protected the cells against cadmium but not methylmercury; (v) AA and LA enrichment had no impact on the cell tolerance to both methylmercury and cadmium; (vi) the abundance of 20:3n-6, a metabolite of the n-6 biotransformation pathway, in

  15. Wheat germ agglutinin as a counterstain for immunofluorescence studies of equine hoof lamellae.

    PubMed

    Clark, Robert K; Galantino-Homer, Hannah L

    2014-09-01

    Equine laminitis is a common, painful, debilitating condition of the hoof that is a leading cause of disability in horses, often necessitating euthanasia. The equine hoof represents an extreme evolutionary adaptation of an epidermal structure homologous to the human or murine nail units. Immunohistochemistry is frequently utilized in the study of the pathophysiology of laminitis. The complex, multilayered, extensively interdigitated epidermal-dermal lamellar interface renders precise interpretation of immunofluorescence localization difficult, especially when effective technique and reagents render non-reactive tissues completely dark. Fluorescent-conjugated wheat germ agglutinin (WGA) selectively labels dermal extracellular matrix fibres and epidermal cell membranes in tissue sections of horse hoof lamellae, is compatible with indirect immunofluorescence and augments interpretation of indirect immunofluorescence antigen localization. The current report details the use of WGA as a rapid, simple, economical counterstain for immunofluorescence studies of the equine hoof and may have application to other complex epidermal tissue structures. PMID:25040657

  16. SIMULTANEOUS DETECTION OF EDWARDSIELLA ICTALURI AND FLAVOBACTERIUM COLUMNARE BY DUAL IMMUNOFLUORESCENCE TEST

    Technology Transfer Automated Retrieval System (TEKTRAN)

    A rapid immunofluorescence test with fluorescent conjugated-antibodies having different spectral properties (Alexa Fluor 488-emitting green fluorescence and Alexa Fluor 594-emitting red fluorescence) was compared with standard bacteriological culture for simultaneous detection of bacterial fish path...

  17. [Quantitative Analysis of Immuno-fluorescence of Nuclear Factor-κB Activation].

    PubMed

    Xiu, Min; He, Feng; Lou, Yuanlei; Xu, Lu; Xiong Jieqi; Wang, Ping; Liu, Sisun; Guo, Fei

    2015-06-01

    Immuno-fluorescence technique can qualitatively determine certain nuclear translocation, of which NF-κB/ p65 implicates the activation of NF-κB signal pathways. Immuno-fluorescence analysis software with independent property rights is able to quantitatively analyze dynamic location of NF-κB/p65 by computing relative fluorescence units in nuclei and cytoplasm. We verified the quantitative analysis by Western Blot. When we applied the software to analysis of nuclear translocation in lipopolysaccharide (LPS) induced (0. 5 h, 1 h, 2 h, 4 h) primary human umbilical vein endothelial cells (HUVECs) , we found that nuclear translocation peak showed up at 2h as with calculated Western blot verification results, indicating that the inventive immuno-fluorescence analysis software can be applied to the quantitative analysis of immuno-fluorescence. PMID:26485997

  18. A comparison of the teratogenicity of methylmercury and selenomethionine injected into bird eggs

    USGS Publications Warehouse

    Heinz, Gary H.; Hoffman, David J.; Klimstra, Jon D.; Stebbins, Katherine R.

    2012-01-01

    Methylmercury chloride and seleno-L-methionine were injected separately or in combinations into the fertile eggs of mallards (Anas platyrhynchos), chickens (Gallus gallus), and double-crested cormorants (Phalacrocorax auritus), and the incidence and types of teratogenic effects were recorded. For all three species,selenomethionine alone caused more deformities than did methylmercury alone. When mallard eggs were injected with the lowest dose of selenium (Se) alone (0.1 μg/g), 28 of 44 embryos and hatchlings were deformed, whereas when eggs were injected with the lowest dose of mercury (Hg) alone (0.2 μg/g), only 1 of 56 embryos or hatchlings was deformed. Mallard embryos seemed to be more sensitive to the teratogenic effects of Se than chicken embryos:0 of 15 chicken embryos or hatchlings from eggs injected with 0.1 μg/g Se exhibited deformities. Sample sizes were small with double-crested cormorant eggs, but they also seemed to be less sensitive to the teratogenic effects of Se than mallard eggs. There were no obvious differences among species regarding Hg-induced deformities. Overall, few interactions were apparent between methylmercury and selenomethionine with respect to the types of deformities observed. However, the deformities spina bifida and craniorachischisis were observed only when Hg and Se were injected in combination. One paradoxical finding was that some doses of methylmercury seemed to counteract the negative effect selenomethionine had on hatching of eggs while at the same time enhancing the negative effect selenomethionine had on creating deformities. When either methylmercury or selenomethionine is injected into avian eggs, deformities start to occur at much lower concentrations than when the Hg or Se is deposited naturally in the egg by the mother.

  19. The oral bioavailability and toxicokinetics of methylmercury in common loon (Gavia immer) chicks

    USGS Publications Warehouse

    Fournier, F.; Karasov, W.H.; Kenow, K.P.; Meyer, M.W.; Hines, R.K.

    2002-01-01

    We compared the toxicokinetics of methylmercury in captive common loon chicks during two time intervals to assess the impact of feather growth on the kinetics of mercury. We also determined the oral bioavailability of methylmercury during these trials to test for age-related changes. The blood concentration-time curves for individuals dosed during feather development (initiated 35 days post hatch) were best described by a one-compartment toxicokinetic model with an elimination half-life of 3 days. The data for birds dosed following completion of feather growth (84 days post hatch) were best fitted by a two-compartment elimination model that includes an initial rapid distribution phase with a half-life of 0.9 days, followed by a slow elimination phase with a half-life of 116 days. We determined the oral bioavailability of methylmercury during the first dosing interval by comparing the ratios of the area under the blood concentration-time curves (AUC0→∞) for orally and intravenously dosed chicks. The oral bioavailability of methylmercury during the first dosing period was 0.83. We also determined bioavailability during both dosing periods using a second measure because of irregularities with intravenous results in the second period. This second bioavailability measure estimated the percentage of the dose that was deposited in the blood volume (f), and the results show that there was no difference in bioavailability among dosing periods. The results of this study highlight the importance of feather growth on the toxicokinetics of methylmercury.

  20. Determination of methylmercury in marine biota samples: method validation.

    PubMed

    Carrasco, Luis; Vassileva, Emilia

    2014-05-01

    Regulatory authorities are expected to measure concentration of contaminants in foodstuffs, but the simple determination of total amount cannot be sufficient for fully judging its impact on the human health. In particular, the methylation of metals generally increases their toxicity; therefore validated analytical methods producing reliable results for the assessment of methylated species are highly needed. Nowadays, there is no legal limit for methylmercury (MeHg) in food matrices. Hence, no standardized method for the determination of MeHg exists within the international jurisdiction. Contemplating the possibility of a future legislative limit, a method for low level determination of MeHg in marine biota matrixes, based on aqueous-phase ethylation followed by purge and trap and gas chromatography (GC) coupled to pyrolysis-atomic fluorescence spectrometry (Py-AFS) detection, has been developed and validated. Five different extraction procedures, namely acid and alkaline leaching assisted by microwave and conventional oven heating, as well as enzymatic digestion, were evaluated in terms of their efficiency to extract MeHg from Scallop soft tissue IAEA-452 Certified Reference Material. Alkaline extraction with 25% (w/w) KOH in methanol, microwave-assisted extraction (MAE) with 5M HCl and enzymatic digestion with protease XIV yielded the highest extraction recoveries. Standard addition or the introduction of a dilution step were successfully applied to overcome the matrix effects observed when microwave-assisted extraction using 25% (w/w) KOH in methanol or 25% (w/v) aqueous TMAH were used. ISO 17025 and Eurachem guidelines were followed to perform the validation of the methodology. Accordingly, blanks, selectivity, calibration curve, linearity (0.9995), working range (1-800pg), recovery (97%), precision, traceability, limit of detection (0.45pg), limit of quantification (0.85pg) and expanded uncertainty (15.86%, k=2) were assessed with Fish protein Dorm-3 Certified

  1. Methylmercury in biota downstream of Arivaca lake, Arizona, USA.

    PubMed

    Marr, Carrie L H; Robertson, Kathy; Reynolds, Kevin D

    2014-04-01

    Concentrations of total mercury (Hg) and methylmercury (MeHg) were determined in water, sediment, periphyton, spiders, and amphibians from the streams and desert marsh downstream from Arivaca Lake, Arizona, to better understand their distribution and bioaccumulation. Mean concentrations of MeHg in water ranged from 0.09 to 0.93 ng/L, and mean concentrations of total Hg in sediment ranged from 10.4 to 126 μg/kg. Hg and MeHg in water and sediments downstream from Arivaca Lake were low enough that they did not exceed human health or ecological thresholds. Hg and MeHg between sites ranged from 0.11 to 1.90 μg/g Hg and 0.01 to 0.3 μg/g MeHg in periphyton, from 0.09 to 0.25 μg/g Hg and 0.04 to 0.10 μg/g MeHg in spiders, and from 0.15 to 0.38 μg/g Hg and 0.14 to 0.35 μg/g MeHg in adult bullfrogs. No Hg toxicity data exist for periphyton or spiders, but MeHg concentrations in tadpoles (0.04 ± 0.005 μg/g) were lower than those known to cause sublethal effects and subchronic mortality. The mean total Hg concentration in adult bullfrogs in the present study was 0.24 μg/g, which is slightly lower than the mean (0.37 μg/g) from an Hg-contaminated wetland in California. MeHg bioaccumulated at each successive trophic level, and MeHg bioconcentration factors from the Arivaca watershed were similar to those for periphyton but greater than amphibians in other studies. Local resource managers can use these data to determine if water should be released from Arivaca Lake to recharge the aquifer downstream or to decrease Hg methylation in the reservoir. PMID:24468966

  2. Variations of attractors and wavelet spectra of the immunofluorescence distributions for women in the pregnant period

    NASA Astrophysics Data System (ADS)

    Galich, Nikolay E.

    2008-07-01

    Communication contains the description of the immunology data treatment. New nonlinear methods of immunofluorescence statistical analysis of peripheral blood neutrophils have been developed. We used technology of respiratory burst reaction of DNA fluorescence in the neutrophils cells nuclei due to oxidative activity. The histograms of photon count statistics the radiant neutrophils populations' in flow cytometry experiments are considered. Distributions of the fluorescence flashes frequency as functions of the fluorescence intensity are analyzed. Statistic peculiarities of histograms set for women in the pregnant period allow dividing all histograms on the three classes. The classification is based on three different types of smoothing and long-range scale averaged immunofluorescence distributions, their bifurcation and wavelet spectra. Heterogeneity peculiarities of long-range scale immunofluorescence distributions and peculiarities of wavelet spectra allow dividing all histograms on three groups. First histograms group belongs to healthy donors. Two other groups belong to donors with autoimmune and inflammatory diseases. Some of the illnesses are not diagnosed by standards biochemical methods. Medical standards and statistical data of the immunofluorescence histograms for identifications of health and illnesses are interconnected. Peculiarities of immunofluorescence for women in pregnant period are classified. Health or illness criteria are connected with statistics features of immunofluorescence histograms. Neutrophils populations' fluorescence presents the sensitive clear indicator of health status.

  3. Mercury Accumulation, Structural Damages, and Antioxidant and Immune Status Changes in the Gilthead Seabream (Sparus aurata L.) Exposed to Methylmercury.

    PubMed

    Guardiola, F A; Chaves-Pozo, E; Espinosa, C; Romero, D; Meseguer, J; Cuesta, A; Esteban, M A

    2016-05-01

    In aquatic systems, mercury (Hg) is an environmental contaminant that causes acute and chronic damage to multiple organs. In fish, practically all of the organic Hg found is in the form of methylmercury (MeHg), which has been associated with animal and human health problems. This study evaluates the impact of waterborne-exposure to sublethal concentrations of MeHg (10 μg L(-1)) in gilthead seabream (Sparus aurata). Hg was seen to accumulate in liver and muscle, and histopathological damage to skin and liver was detected. Fish exposed to MeHg showed a decreased biological antioxidant potential and increased levels of the reactive oxygen molecules compared with the values found in control fish (nonexposed). Increased liver antioxidant enzyme activities (superoxide dismutase and catalase) were detected in 2 day-exposed fish with respect to the values of control fish. However, fish exposed to MeHg for 10 days showed liver antioxidant enzyme levels similar to those of the control fish but had increased hepato-somatic index and histopathological alterations in liver and skin. Serum complement levels were higher in fish exposed to MeHg for 30 days than in control fish. Moreover, head-kidney leukocyte activities increased, although only phagocytosis and peroxidase activities showed a significant increase after 10 and 30 days, respectively. The data show that 30 days of exposure to waterborne MeHg provokes more significant changes in fish than a short-term exposure of 2 or 10 days. PMID:26906265

  4. Protective effects of the flavonoid chrysin against methylmercury-induced genotoxicity and alterations of antioxidant status, in vivo.

    PubMed

    Manzolli, Eduardo Scandinari; Serpeloni, Juliana Mara; Grotto, Denise; Bastos, Jairo Kennup; Antunes, Lusânia Maria Greggi; Barbosa Junior, Fernando; Barcelos, Gustavo Rafael Mazzaron

    2015-01-01

    The use of phytochemicals has been widely used as inexpensive approach for prevention of diseases related to oxidative damage due to its antioxidant properties. One of dietary flavonoids is chrysin (CR), found mainly in passion fruit, honey, and propolis. Methylmercury (MeHg) is a toxic metal whose main toxic mechanism is oxidative damage. Thus, the study aimed to evaluate the antioxidant effects of CR against oxidative damage induced by MeHg in Wistar rats. Animals were treated with MeHg (30 µg/kg/bw) in presence and absence of CR (0.10, 1.0, and 10 mg/kg/bw) by gavage for 45 days. Glutathione (GSH) in blood was quantified spectrophotometrically and for monitoring of DNA damage, comet assay was used in leukocytes and hepatocytes. MeHg led to a significant increase in the formation of comets; when the animals were exposed to the metal in the presence of CR, higher concentrations of CR showed protective effects. Moreover, exposure to MeHg decreased the levels of GSH and GSH levels were restored in the animals that received CR plus MeHg. Taken together the findings of the present work indicate that consumption of flavonoids such as CR may protect humans against the adverse health effects caused by MeHg. PMID:25810809

  5. Low-Dose Methylmercury-Induced Apoptosis and Mitochondrial DNA Mutation in Human Embryonic Neural Progenitor Cells

    PubMed Central

    Yan, Mengling; Zhao, Lina; Wu, Qing; Wu, Chunhua

    2016-01-01

    Methylmercury (MeHg) is a long-lasting organic pollutant primarily found in the aquatic environment. The developing brain is particularly sensitive to MeHg due to reduced proliferation of neural stem cell. Although several mechanisms of MeHg-induced apoptosis have been defined in culture models, it remains unclear whether mitochondrial DNA (mtDNA) mutation is involved in the toxic effect of MeHg, especially in the neural progenitor cells. In the present study, the ReNcell CX cell, a human neural progenitor cells (hNPCs) line, was exposed to nanomolar concentrations of MeHg (≤50 nM). We found that MeHg altered mitochondrial metabolic function and induced apoptosis. In addition, we observed that MeHg induced ROS production in a dose-dependent manner in hNPCs cells, which was associated with significantly increased expressions of ND1, Cytb, and ATP6. To elucidate the mechanism underlying MeHg toxicity on mitochondrial function, we examined the ATP content and mitochondrial membrane potential in MeHg-treated hNPCs. Our study showed that MeHg exposure led to decreased ATP content and reduced mitochondrial membrane potential, which failed to match the expansion in mtDNA copy number, suggesting impaired mtDNA. Collectively, these results demonstrated that MeHg induced toxicity in hNPCs through altering mitochondrial function and inducing oxidative damage to mtDNA. PMID:27525052

  6. Low-Dose Methylmercury-Induced Apoptosis and Mitochondrial DNA Mutation in Human Embryonic Neural Progenitor Cells.

    PubMed

    Wang, Xinjin; Yan, Mengling; Zhao, Lina; Wu, Qing; Wu, Chunhua; Chang, Xiuli; Zhou, Zhijun

    2016-01-01

    Methylmercury (MeHg) is a long-lasting organic pollutant primarily found in the aquatic environment. The developing brain is particularly sensitive to MeHg due to reduced proliferation of neural stem cell. Although several mechanisms of MeHg-induced apoptosis have been defined in culture models, it remains unclear whether mitochondrial DNA (mtDNA) mutation is involved in the toxic effect of MeHg, especially in the neural progenitor cells. In the present study, the ReNcell CX cell, a human neural progenitor cells (hNPCs) line, was exposed to nanomolar concentrations of MeHg (≤50 nM). We found that MeHg altered mitochondrial metabolic function and induced apoptosis. In addition, we observed that MeHg induced ROS production in a dose-dependent manner in hNPCs cells, which was associated with significantly increased expressions of ND1, Cytb, and ATP6. To elucidate the mechanism underlying MeHg toxicity on mitochondrial function, we examined the ATP content and mitochondrial membrane potential in MeHg-treated hNPCs. Our study showed that MeHg exposure led to decreased ATP content and reduced mitochondrial membrane potential, which failed to match the expansion in mtDNA copy number, suggesting impaired mtDNA. Collectively, these results demonstrated that MeHg induced toxicity in hNPCs through altering mitochondrial function and inducing oxidative damage to mtDNA. PMID:27525052

  7. Oral bioaccessibility of arsenic, mercury and methylmercury in marine species commercialized in Catalonia (Spain) and health risks for the consumers.

    PubMed

    Cano-Sancho, German; Perelló, Gemma; Maulvault, Ana Luísa; Marques, António; Nadal, Martí; Domingo, José L

    2015-12-01

    This study was aimed at characterizing the bioaccessibility of arsenic (As), mercury (Hg) and methylmercury (MeHg) in commercial fish and seafood species widely consumed by the population of Catalonia (Spain). An accurate evaluation on how bioaccessibility estimations may affect the outcomes of exposure assessment studies was also conducted. The concentrations of As, Hg, and MeHg in samples of fish and seafood incubated in a 3-compartmental (mouth, stomach, and small intestine) in vitro gastrointestinal model, were quantified and compared with the levels of these elements in cooked samples. Arsenic showed a high bioaccessibility in all the fish and seafood species, ranging from 72% (mackerel) to 89% (sardine). In contrast, the bioaccessibility of Hg was rather lower, being <50% for most species, while MeHg could be only quantified in swordfish and tuna. This study elucidates the potential overestimation of health risks to consumers, when the effects of bioaccessibility and cooking procedures are not taken into account in the risk assessment. Unlike As, whose risk is not generally overestimated, Hg and MeHg showed a lower and variable bioaccessibility in marine species, meaning an overestimation of health risks for the adult population. Further studies should assess the bioaccessibility of mercurial species for children. PMID:26409124

  8. [Pollution Characteristics Analysis and Risk Assessment of Total Mercury and Methylmercury in Aquatic Products of the Haihe Stem River].

    PubMed

    Tong, Yin-dong; Zhang, Wei; Deng, Chun-yan; Wang, Xue-jun

    2016-03-15

    In this study, we analyzed the concentrations of total mercury (THg) and methylmercury (MeNg) in the aquatic products from the Haihe Stem River, and also assessed the risk for the consumers. According to our results, the MeHg and THg concentrations in the aquatic products were 42.51 and 77.31 ng · g⁻¹, respectively (wet weight) . The majority of THg in the aquatic products existed in the form of MeHg (accounting for over 50%). The mercury concentrations varied significantly among different organs in the fish. The BCFs of MeHg for the fish and zoobenthos in the Haihe River were 1.00 x 10 and 4.23 x 10⁴mLg , respectively. Compared with THg, MeHg could accumulate more easily in the aquatic products. Generally, the maximum MeHg and THg concentrations of the aquatic products were much lower than the limit values in China. However, compared with the adults, the MeHg exposure risk for the children was higher, and the THg and MeHg intake could be as high as 154.07 ng (kgd) and 81.11 ng (kg.d)⁻¹, respectively. PMID:27337885

  9. Influence of food, aquatic humus, and alkalinity on methylmercury uptake by Daphnia magna

    SciTech Connect

    Monson, B.A.; Brezonik, P.L.

    1999-03-01

    Six-day-old Daphnia magna were exposed to low concentrations of methylmercury (MeHg) in synthetic freshwater and synthetic food. Uptake kinetics were determined in 24- to 72-h experiments, measuring both the loss of Hg from water and accumulation in D. magna. Dose-uptake response was linear for MeHg concentrations up to 4.0 ng/L; an initial concentration of 2.0 ng/L was used when other factors were varied. Concentrations of total Hg and MeHg in water and D. magna were measured in treatments with varied hardness and alkalinity, aquatic humus (AH), and food spiked with MeHg versus water spiked with MeHg. Uptake rate coefficients were derived from two versions of a first-order, two-compartment model. The first version assumed constant MeHg concentration; the second accounted for changing MeHg concentration in water over time. Both models accounted for a nonzero starting concentration of MeHg in plankton. Fitted rate coefficients were higher for the second model than the first: the uptake coefficient (k{sub u}) was nine times higher; the depuration coefficient (k{sub d}) was twice as high. Assuming a constant MeHg concentration for a one-time spike thus underestimated the rate coefficient. The source of MeHg was compared by exposing D. magna for 48 h to MeHg at 2 ng/L in food or water. Daphnia magna accumulated significantly more inorganic Hg (i.e., Hg{sup 2+}) from spiked food than from spiked water, but accumulation of MeHg was the same from both sources. A similar response was found when D. magna were exposed to a lake water extraction of AH at concentrations of C at 3 and 10 mg/L. At the higher AH concentration, total Hg in daphnids was higher, but MeHg was lower, suggesting that AH was a source of inorganic Hg but reduced the bioavailability of MeHg. Exposure of D. magna to MeHg at 2 ng/L in hard or soft water adjusted to pH 6.7 showed no significant difference in MeHg uptake, supporting an argument that hardness and alkalinity per se do not affect MeHg uptake by

  10. Museum Preserved Bivalves as Indicators of Long-term Trends in Methylmercury Concentrations

    NASA Astrophysics Data System (ADS)

    Luengen, A. C.; Foslund, H. M.; Greenfield, B. K.

    2015-12-01

    Despite the many efforts to reduce mercury concentrations in the environment, there are relatively few datasets on long-term trends in mercury in biota, especially for the bioavailable form, methylmercury (MeHg). This study used museum preserved bivalves (stored in ethanol) to look at MeHg trends in the Asian date mussel Musculista senhousia and the Asian clam Potamocorbula amurensis, collected from San Francisco Bay, California between 1975 and 2012. For each sampling date, 4 to 15 individuals were obtained from museum collections (N = 156 total specimens), freeze-dried, weighed, homogenized, digested, and individually analyzed for MeHg using trace metal clean techniques. The bivalves were also analyzed for δ13C and δ15N to look for changes in food web structure. P. amurensis specimens were only available from 1988 to 2012, and an increase in MeHg was observed during that time. In contrast, M. senhousia specimens were available for the entire 37 year period and exhibited a significant decline in MeHg in the southern reach of the estuary (South Bay). The median MeHg concentration in M. senhousia was highest at 239 ng/g dw in October 1975. That year was the last year of operations for the New Almaden Mercury Mining District, which drained into South Bay. By the 1990s, MeHg concentrations in M. senhousia dropped significantly to a median of 37 ng/g dw. Isotopic δ15N values did not support a hypothesis of reduced trophic position causing the MeHg decline. Over the study duration, δ15N increased in M. senhousia, which we attributed to a baseline shift. We also observed a decline in δ13C since 2000, which may represent a shift in bivalve carbon towards greater utilization of planktonic sources. To validate the use of museum specimens, we ran a preservation study, where we collected fresh bivalves, fixed them in ethanol or formalin, and then transferred them to ethanol for long-term storage. Although MeHg concentrations increased after 1 week, they stabilized over

  11. POSTNATAL METHYL MERCURY EXPOSURE: EFFECTS ON ONTOGENY OF RENAL AND HEPATIC ORNITHINE DECARBOXYLASE RESPONSES TO TROPHIC STIMULI

    EPA Science Inventory

    The effects of postnatal methylmercury exposure on the ongoteny of kidney and liver responsiveness to trophic stimuli were examined. Increased ornithine decarboxylase (ODC) activity was used as an index of tissue stimulation. In the rat, kidney ODC responsiveness to growth hormon...

  12. Supercritical fluid carbon dioxide extraction and liquid chromatographic separation with electrochemical detection of methylmercury from biological samples

    USGS Publications Warehouse

    Simon, N.S.

    1997-01-01

    Using the coupled methods presented in this paper, methylmercury can be accurately and rapidly extracted from biological samples by modified supercritical fluid carbon dioxide and quantitated using liquid chromatography with reductive electrochemical detection. Supercritical fluid carbon dioxide modified with methanol effectively extracts underivatized methylmercury from certified reference materials Dorm-1 (dogfish muscle) and Dolt-2 (dogfish liver). Calcium chloride and water, with a ratio of 5:2 (by weight), provide the acid environment required for extracting methylmercury from sample matrices. Methylmercury chloride is separated from other organomercury chloride compounds using HPLC. The acidic eluent, containing 0.06 mol L-1 NaCl, insures the presence of methylmercury chloride and facilitates the reduction of mercury on a glassy carbon electrode. If dual glassy carbon electrodes are used, a positive peak is observed at -0.65 to -0.70 V and a negative peak is observed at -0.90V with the organomercury compounds that were tested. The practical detection limit for methylmercury is 5 X 10-8 mol L-1 (1 X 10-12 tool injected) when a 20 ??L injection loop is used.

  13. Bioenergetic and pharmacokinetic model for exposure of common loon (Gavia immer) chicks to methylmercury

    USGS Publications Warehouse

    Karasov, W.H.; Kenow, K.P.; Meyer, M.W.; Fournier, F.

    2007-01-01

    A bioenergetics model was used to predict food intake of common loon (Gavia immer) chicks as a function of body mass during development, and a pharmacokinetics model, based on first-order kinetics in a single compartment, was used to predict blood Hg level as a function of food intake rate, food Hg content, body mass, and Hg absorption and elimination. Predictions were tested in captive growing chicks fed trout (Salmo gairdneri) with average MeHg concentrations of 0.02 (control), 0.4, and 1.2 ??g/g wet mass (delivered as CH3HgCl). Predicted food intake matched observed intake through 50 d of age but then exceeded observed intake by an amount that grew progressively larger with age, reaching a significant overestimate of 28% by the end of the trial. Respiration in older, nongrowing birds probably was overestimated by using rates measured in younger, growing birds. Close agreement was found between simulations and measured blood Hg, which varied significantly with dietary Hg and age. Although chicks may hatch with different blood Hg levels, their blood level is determined mainly by dietary Hg level beyond approximately two weeks of age. The model also may be useful for predicting Hg levels in adults and in the eggs that they lay, but its accuracy in both chicks and adults needs to be tested in free-living birds. ?? 2007 SETAC.

  14. Determinants of polychlorinated biphenyls and methylmercury exposure in inuit women of childbearing age.

    PubMed Central

    Muckle, G; Ayotte, P; Dewailly E; Jacobson, S W; Jacobson, J L

    2001-01-01

    The objectives of this study were to to identify maternal characteristics associated with traditional food consumption and to examine food items associated with polychlorinated biphenyls (PCBs) and mercury body burden in pregnant Inuit women from Northern Québec. We interviewed women from three communities at mid-pregnancy and at 1 and 11 months postpartum. We measured PCBs, Hg, and selenium in maternal blood; Hg was also measured in maternal hair. The women reported eating significant amounts of fish, beluga muktuk/fat, seal meat, and seal fat. Although consumption of fish and seal was associated with lower socioeconomic status, consumption of beluga whale was uniform across strata. Fish and seal meat consumption was associated with increased Hg concentrations in hair. Traditional food intake during pregnancy was unrelated to PCB body burden, which is more a function of lifetime consumption. This study corroborated previous findings relating marine mammal and fish consumption to increased Hg and selenium body burden. Despite widespread knowledge regarding the presence of these contaminants in traditional foods, a large proportion of Inuit women increased their consumption of these foods during pregnancy, primarily because of pregnancy-related changes in food preferences and the belief that these foods are beneficial during pregnancy. PMID:11673127

  15. Methylmercury degradation and exposure pathways in streams and wetlands impacted by historical mining.

    PubMed

    Donovan, Patrick M; Blum, Joel D; Singer, Michael Bliss; Marvin-DiPasquale, Mark; Tsui, Martin T K

    2016-10-15

    Monomethyl mercury (MMHg) and total mercury (THg) concentrations and Hg stable isotope ratios (δ(202)Hg and Δ(199)Hg) were measured in sediment and aquatic organisms from Cache Creek (California Coast Range) and Yolo Bypass (Sacramento Valley). Cache Creek sediment had a large range in THg (87 to 3870ng/g) and δ(202)Hg (-1.69 to -0.20‰) reflecting the heterogeneity of Hg mining sources in sediment. The δ(202)Hg of Yolo Bypass wetland sediment suggests a mixture of high and low THg sediment sources. Relationships between %MMHg (the percent ratio of MMHg to THg) and Hg isotope values (δ(202)Hg and Δ(199)Hg) in fish and macroinvertebrates were used to identify and estimate the isotopic composition of MMHg. Deviation from linear relationships was found between %MMHg and Hg isotope values, which is indicative of the bioaccumulation of isotopically distinct pools of MMHg. The isotopic composition of pre-photodegraded MMHg (i.e., subtracting fractionation from photochemical reactions) was estimated and contrasting relationships were observed between the estimated δ(202)Hg of pre-photodegraded MMHg and sediment IHg. Cache Creek had mass dependent fractionation (MDF; δ(202)Hg) of at least -0.4‰ whereas Yolo Bypass had MDF of +0.2 to +0.5‰. This result supports the hypothesis that Hg isotope fractionation between IHg and MMHg observed in rivers (-MDF) is unique compared to +MDF observed in non-flowing water environments such as wetlands, lakes, and the coastal ocean. PMID:27234290

  16. The effects of prenatal exposure to methylmercury on aggressive behavior in the rat.

    PubMed

    Royalty, J; Taylor, G T; Korol, B A

    1987-01-01

    The sensitivity of isolation-induced aggressive behavior to prenatal treatment of 6.0 mg/kg methylmercuric chloride (MMCl) by gavage on gestation days 6-9 was assessed in a subset of animals from the Collaborative Behavioral Teratology Study (CBTS). CBTS behavioral measures consisted of negative geotaxis, olfactory discrimination, auditory startle habituation, 1-hr activity, 23-hr activity, activity following pharmacological challenge and visual discrimination learning. Auditory startle was the only CBTS behavioral measure that discriminated among prenatal treatment groups. MMCl animals also were reliably more aggressive than vehicle controls in dyadic encounters. The results suggest that tests of aggressive behavior, which rarely have been included in teratologic assessments, be considered in the formulation of behavioral screening paradigms. The advantages of including tests of aggression and the relationship between aggressive and startle responses are discussed. PMID:3657757

  17. Distribution and transport of total mercury and methylmercury in mercury-contaminated sediments in reservoirs and wetlands of the Sudbury River, east-central Massachusetts

    USGS Publications Warehouse

    Colman, John A.; Waldron, Marcus C.; Breault, Robert F.; Lent, Robert M.

    1999-01-01

    Total mercury and methylmercury were measured in 4 reservoir cores and 12 wetland cores from Sudbury River. The distribution of total mercury and methylmercury in these cores was evaluated to determine the potential for total mercury and methylmercury transport from reservoir and wetlands sediments to the water column. Concentrations of methylmercury were corrected for an analytical artifact introduced during the separation distillation used in the analysis procedure. Corrected methylmercury concentrations correlated with total mercury concentrations in bulk sediment from below the top layers of reservoir and wetland cores; methylmercury concentrations at the top layers of cores were relatively high, however, and were not correlated with total mercury concentrations. Concentrations of methylmercury in pore water were positively correlated with methylmercury concentrations in the bulk sediment. High concentrations of total mercury and methylmercury in sediment (73 and 0.047 micrograms per gram dry-weight basis, respectively) contributed less to the water column in the reservoir than in the wetlands probably because of burial by low concentration sediment and differences in the processes available to transport mercury from the sediments to the water in the reservoirs, as compared to the wetlands .

  18. Sulfur and Methylmercury in the Florida Everglades - the Biogeochemical Connection

    NASA Astrophysics Data System (ADS)

    Orem, W. H.; Gilmour, C. C.; Krabbenhoft, D. P.; Aiken, G.

    2011-12-01

    Methylmercury (MeHg) is a serious environmental problem in aquatic ecosystems worldwide because of its toxicity and tendency to bioaccumulate. The Everglades receives some of the highest levels of atmospheric mercury deposition and has some of the highest levels of MeHg in fish in the USA, posing a threat to pisciverous wildlife and people through fish consumption. USGS studies show that a combination of biogeochemical factors make the Everglades especially susceptible to MeHg production and bioaccumulation: (1) vast wetland area with anoxic soils supporting anaerobic microbial activity, (2) high rates of atmospheric mercury deposition, (3) high levels of dissolved organic carbon (DOC) that complexes and stabilizes mercury in solution for transport to sites of methylation, and (4) high sulfate loading in surface water that drives microbial sulfate reduction and mercury methylation. The high levels of sulfate in the Everglades represent an unnatural condition. Background sulfate levels are estimated to be <1 mg/L, but about 60% of the Everglades has surface water sulfate concentrations exceeding background. Highly sulfate-enriched marshes in the northern Everglades have average sulfate levels of 60 mg/L. Sulfate loading to the Everglades is principally a result of land and water management in south Florida. The highest concentrations of sulfate, averaging 60-70 mg/L, are in canal water in the Everglades Agricultural Area (EAA). Geochemical data and a preliminary sulfur mass balance for the EAA are consistent with sulfur currently used in agriculture, and sulfur released by oxidation of organic EAA soils (including legacy agricultural applications and natural sulfur) as the primary sources of sulfate enrichment to the canals and ecosystem. Sulfate loading increases microbial sulfate reduction and MeHg production in soils. The relationship between sulfate loading and MeHg production, however, is complex. Sulfate levels up to about 20-30 mg/L increase mercury

  19. Effect of Marine Omega 3 Fatty Acids on Methylmercury-Induced Toxicity in Fish and Mammalian Cells In Vitro

    PubMed Central

    Nøstbakken, O. J.; Bredal, I. L.; Olsvik, P. A.; Huang, T. S.; Torstensen, B. E.

    2012-01-01

    Methylmercury (MeHg) is a ubiquitous environmental contaminant which bioaccumulates in marine biota. Fish constitute an important part of a balanced human diet contributing with health beneficial nutrients but may also contain contaminants such as MeHg. Interactions between the marine n-3 fatty acids eicosapentaenoic acid (20:5n-3, EPA) and docosahexaenoic acid (22:6n-3, DHA) with MeHg-induced toxicity were investigated. Different toxic and metabolic responses were studied in Atlantic salmon kidney (ASK) cell line and the mammalian kidney-derived HEK293 cell line. Both cell lines were preincubated with DHA or EPA prior to MeHg-exposure, and cell toxicity was assessed differently in the cell lines by MeHg-uptake in cells (ASK and HEK293), proliferation (HEK293 and ASK), apoptosis (ASK), oxidation of the red-ox probe roGFP (HEK293), and regulation of selected toxicological and metabolic transcriptional markers (ASK). DHA was observed to decrease the uptake of MeHg in HEK293, but not in ASK cells. DHA also increased, while EPA decreased, MeHg-induced apoptosis in ASK. MeHg exposure induced changes in selected metabolic and known MeHg biomarkers in ASK cells. Both DHA and MeHg, but not EPA, oxidized roGFP in HEK293 cells. In conclusion, marine n-3 fatty acids may ameliorate MeHg toxicity, either by decreasing apoptosis (EPA) or by reducing MeHg uptake (DHA). However, DHA can also augment MeHg toxicity by increasing oxidative stress and apoptosis when combined with MeHg. PMID:22654480

  20. Methods for Individualized Determination of Methylmercury Elimination Rate and De-Methylation Status in Humans Following Fish Consumption.

    PubMed

    Rand, Mathew D; Vorojeikina, Daria; van Wijngaarden, Edwin; Jackson, Brian P; Scrimale, Thomas; Zareba, Grazyna; Love, Tanzy M; Myers, Gary J; Watson, Gene E

    2016-02-01

    Methylmercury (MeHg) exposure via fish in the diet remains a priority public health concern. Individual variation in response to a given MeHg exposure and the biotransformation of MeHg that follows complicate our understanding of this issue. MeHg elimination from the human body occurs slowly (elimination rate (kel) approximately 0.01 day(-1) or approximately 70 days half-life [t1/2]) and is a major determinant of the Hg body burden resulting from fish consumption. The underlying mechanisms that control MeHg elimination from the human body remain poorly understood. We describe here improved methods to obtain a MeHg elimination rate via longitudinal Hg analysis in hair using laser ablation-inductively coupled plasma-mass spectrometry. We measured MeHg elimination rates in eight individuals following the consumption of 3 fish meals in two 75-day trials separated by a 4-month washout period. In addition, since MeHg biotransformation to inorganic Hg (I-Hg) is associated with Hg excretion, we speciated Hg in feces samples to estimate individual MeHg de-methylation status. We observed a wide range of MeHg elimination rates between individuals and within individuals over time (kel = 0.0163-0.0054 day(-1); estimated t1/2 = 42.5-128.3 days). The ratio of MeHg and I-Hg in feces also varied widely among individuals. While the %I-Hg in feces was likely influenced by dental amalgams, findings with subjects who lacked amalgams suggest that faster MeHg elimination is associated with a higher %I-Hg in feces indicating more complete de-methylation. We anticipate these methods will contribute to future investigations of genetic and dietary factors that influence MeHg disposition in people. PMID:26572661

  1. Gene expression, glutathione status and indicators of hepatic oxidative stress in laughing gull (Larus atricilla) hatchlings exposed to methylmercury

    USGS Publications Warehouse

    Jenko, Kathryn; Karouna-Renier, Natalie K.; Hoffman, David J.

    2012-01-01

    Despite extensive studies of methylmercury (MeHg) toxicity in birds, molecular effects on birds are poorly characterized. To improve our understanding of toxicity pathways and identify novel indicators of avian exposure to Hg, the authors investigated genomic changes, glutathione status, and oxidative status indicators in liver from laughing gull (Larus atricilla) hatchlings that were exposed in ovo to MeHg (0.05–1.6 µg/g). Genes involved in the transsulfuration pathway, iron transport and storage, thyroid-hormone related processes, and cellular respiration were identified by suppression subtractive hybridization as differentially expressed. Quantitative polymerase chain reaction (qPCR) identified statistically significant effects of Hg on cytochrome C oxidase subunits I and II, transferrin, and methionine adenosyltransferase RNA expression. Glutathione-S-transferase activity and protein-bound sulfhydryl levels decreased, whereas glucose-6-phosphate dehydrogenase activity increased dose-dependently. Total sulfhydryl concentrations were significantly lower at 0.4 µg/g Hg than in controls. T ogether, these endpoints provided some evidence of compensatory effects, but little indication of oxidative damage at the tested doses, and suggest that sequestration of Hg through various pathways may be important for minimizing toxicity in laughing gulls. This is the first study to describe the genomic response of an avian species to Hg. Laughing gulls are among the less sensitive avian species with regard to Hg toxicity, and their ability to prevent hepatic oxidative stress may be important for surviving levels of MeHg exposures at which other species succumb.

  2. Methylmercury alters glutathione homeostasis by inhibiting glutaredoxin 1 and enhancing glutathione biosynthesis in cultured human astrocytoma cells.

    PubMed

    Robitaille, Stephan; Mailloux, Ryan J; Chan, Hing Man

    2016-08-10

    Methylmercury (MeHg) is a neurotoxin that binds strongly to thiol residues on protein and low molecular weight molecules like reduced glutathione (GSH). The mechanism of its effects on GSH homeostasis particularly at environmentally relevant low doses is not fully known. We hypothesized that exposure to MeHg would lead to a depletion of reduced glutathione (GSH) and an accumulation of glutathione disulfide (GSSG) leading to alterations in S-glutathionylation of proteins. Our results showed exposure to low concentrations of MeHg (1μM) did not significantly alter GSH levels but increased GSSG levels by ∼12-fold. This effect was associated with a significant increase in total cellular glutathione content and a decrease in GSH/GSSG. Immunoblot analyses revealed that proteins involved in glutathione synthesis were upregulated accounting for the increase in cellular glutathione. This was associated an increase in cellular Nrf2 protein levels which is required to induce the expression of antioxidant genes in response to cellular stress. Intriguingly, we noted that a key enzyme involved in reversing protein S-glutathionylation and maintaining glutathione homeostasis, glutaredoxin-1 (Grx1), was inhibited by ∼50%. MeHg treatment also increased the S-glutathionylation of a high molecular weight protein. This observation is consistent with the inhibition of Grx1 and elevated H2O2 production however; contrary to our original hypothesis we found few S-glutathionylated proteins in the astrocytoma cells. Collectively, MeHg affects multiple arms of glutathione homeostasis ranging from pool management to protein S-glutathionylation and Grx1 activity. PMID:27180086

  3. Liver mercury and methylmercury concentrations in New England common loons (Gavia immer)

    SciTech Connect

    Pokras, M.A.; Hanley, C.; Gordon, Z.

    1998-02-01

    Loons are of special interest to environmental scientists, who see them as a sentinel species for environmental health. This bird is a top predator in both fresh- and saltwater environments. A number of studies have been published regarding contaminant-related loon pathology, and they have repeatedly found Hg contamination and ingestion of lead fishing gear to be of particular concern. Since 1989 the authors have been studying regional patterns of loon mortality and have examined more than 400 birds. One segment of this study has been to document contaminants found in loons and to attempt to associate health effects with these contaminants. This article details some of their work on Hg in loons. Liver samples collected from common loons found dead were analyzed for mercury and methylmercury concentrations. Statistical analyses demonstrated no correlation between total mercury and methylmercury levels.

  4. Accumulation of methylmercury in the earthworm, Eisenia foetida, and its effect on regeneration

    SciTech Connect

    Beyer, W.N.; Cromartie, E.; Moment, G.B.

    1985-08-01

    Earthworms provide an appropriate model for evaluating the environmental hazards of metals in soil, and they are also excellent organisms for studying the process of regeneration. Two studies have found that concentrations of mercury in earthworms were higher than those in the soil where they lived. This study investigates the accumulation of methylmercury in the earthworm, Eisenia foetida (Savigny), and its effect on regeneration after excision of the caudal end.

  5. Comparison of direct mercury analyzer and FIA-CV-AAS in determination of methylmercury in fish

    NASA Astrophysics Data System (ADS)

    Ulrich, J. C.; Hortellani, M. A.; Sarkis, J. E. S.; Nakatsubo, M. A.

    2016-07-01

    Methylmercury (MeHg) has been determined in fish reference materials by direct mercury analyzer (DMA 80) and FIA-CV-AAS. In order to evaluate accuracy, certified reference materials (Fish protein, NRCC - Dorm 4 and fish material, Ipen - Dourada 1) were analyzed after extraction and separation of mercury species. Good agreement of the results have been obtained (relative error of the determination between the methods varied from 1.5% to 39%). The repeatability of the results varied from 4% to 26%.

  6. A Versatile Method for Immunofluorescent Staining of Cells Cultured on Permeable Membrane Inserts.

    PubMed

    Gillespie, Jenni L; Anyah, Anwuli; Taylor, John M; Marlin, Jerry W; Taylor, Tracey A H

    2016-01-01

    BACKGROUND Obtaining high-quality images of cellular structures via immunofluorescence staining is critical for cellular localization studies. Often, these studies cannot be performed in parallel with certain oncology, virology, pharmacokinetic, and drug absorption studies due to model system technicalities requiring the cells to be cultured on porous membranes rather than glass or plastic. MATERIAL AND METHODS Here, we report a method of immunofluorescent staining of cells cultured on permeable membranes. RESULTS As proof of principle, HeLa cells grown on Transwell® membrane supports were stained with fluorescently labeled antibodies using this modified immunofluorescence staining method and visualized by fluorescent microscopy. CONCLUSIONS This protocol is a convenient alternative to staining cells on glass coverslips, thereby expanding the scope and applications of this important research tool. PMID:27616137

  7. Identifying the Spatial Relationships of Thymic Stromal and Thymocyte Subsets by Immunofluorescence Analysis.

    PubMed

    Bain, Virginia; Richie, Ellen R

    2016-01-01

    Immunofluorescence analysis of thymic tissue sections is an indispensable technique for visualizing spatial relationships among thymocyte and stromal cell subsets. The thymus is organized into distinct microenvironmental zones in which particular thymic epithelial cell (TEC) subsets support specific stages of thymocyte maturation. Conversely, thymocytes and lymphoid tissue inducer cells support functional maturation of TECs. The composition and organization of TECs change during ontogeny to generate a maximally functional organ in the young adult. Deterioration of thymic architecture and stromal organization occurs with age as the thymus undergoes involution. Such changes can be monitored by immunofluorescent staining of thymic sections obtained at different ages throughout the life-span. Here we describe methods to generate frozen or paraffin-embedded thymic tissue sections for multicolor immunofluorescence staining using antibodies to surface and/or cytoplasmic antigens. PMID:26294399

  8. The fate and transport of mercury, methylmercury, and other trace metals in Chesapeake Bay tributaries.

    PubMed

    Lawson, N M; Mason, R P; Laporte, J M

    2001-02-01

    Six tributaries to the Chesapeake Bay were analyzed for suspended particulate matter, dissolved organic carbon, particulate organic carbon, mercury, methylmercury, lead, nickel, zinc, cadmium, chromium, and copper. This study examined the importance of flow regime, suspended particulate concentration, and watershed characteristics on the transport of mercury, methylmercury, and other trace metals. Total mercury concentrations were higher under high flow conditions which is consistent with the tendency of this metal to bind strongly to particulate matter. Methylmercury showed less flow rate dependence. Nickel, lead, and zinc concentrations responded strongly to flow rate on the Potomac River, while weaker correlations were found on the other rivers sampled. Cadmium, copper, and chromium concentrations were the least influenced by flow. Partition coefficients calculated in this study were similar to those of other estuaries and overall decreased in the order of Hg > Ni-MMHg > Cr-Pb-Zn > Cd > Cu. Watershed yield estimates and associated retention factors were calculated for the various rivers. These calculations showed that for most of the rivers, mercury was the most strongly retained within the watershed. PMID:11229005

  9. Toward Bioremediation of Methylmercury Using Silica Encapsulated Escherichia coli Harboring the mer Operon.

    PubMed

    Kane, Aunica L; Al-Shayeb, Basem; Holec, Patrick V; Rajan, Srijay; Le Mieux, Nicholas E; Heinsch, Stephen C; Psarska, Sona; Aukema, Kelly G; Sarkar, Casim A; Nater, Edward A; Gralnick, Jeffrey A

    2016-01-01

    Mercury is a highly toxic heavy metal and the ability of the neurotoxin methylmercury to biomagnify in the food chain is a serious concern for both public and environmental health globally. Because thousands of tons of mercury are released into the environment each year, remediation strategies are urgently needed and prompted this study. To facilitate remediation of both organic and inorganic forms of mercury, Escherichia coli was engineered to harbor a subset of genes (merRTPAB) from the mercury resistance operon. Protein products of the mer operon enable transport of mercury into the cell, cleavage of organic C-Hg bonds, and subsequent reduction of ionic mercury to the less toxic elemental form, Hg(0). E. coli containing merRTPAB was then encapsulated in silica beads resulting in a biological-based filtration material. Performing encapsulation in aerated mineral oil yielded silica beads that were smooth, spherical, and similar in diameter. Following encapsulation, E. coli containing merRTPAB retained the ability to degrade methylmercury and performed similarly to non-encapsulated cells. Due to the versatility of both the engineered mercury resistant strain and silica bead technology, this study provides a strong foundation for use of the resulting biological-based filtration material for methylmercury remediation. PMID:26761437

  10. Effects of chronic, low concentrations of dietary methylmercury on the behavior of juvenile great egrets

    SciTech Connect

    Bouton, S.N.; Frederick, P.C.; Spalding, M.G.; McGill, H.

    1999-09-01

    The authors measured the behavioral effects of methylmercury on 16 great egret chicks (Ardea albus) in a captive dosing experiment. Birds were randomly divided into a control group and groups that received 0.5 or 5 mg methylmercury chloride per kilogram of food at between 12 and 105 d of age. They recorded activity levels, maintenance behavior, and foraging efficiency and determined that mercury affected activity and maintenance behavior. Birds dosed with 5 mg/kg became severely ataxic and were euthanized by 12 weeks of age. The authors found that, during the postfledging period, there were no differences between low-dose and placebo birds in time required to capture live fish in pools or in efficiency of capture. They did find that low-dose birds were less likely to hunt fish. Their results suggest that, at the 0.5 mg/kg concentration in food, there are significant effects of methylmercury on activity, tendency to seek shade, and motivation to hunt prey.

  11. Toward Bioremediation of Methylmercury Using Silica Encapsulated Escherichia coli Harboring the mer Operon

    PubMed Central

    Kane, Aunica L.; Al-Shayeb, Basem; Holec, Patrick V.; Rajan, Srijay; Le Mieux, Nicholas E.; Heinsch, Stephen C.; Psarska, Sona; Aukema, Kelly G.; Sarkar, Casim A.; Nater, Edward A.; Gralnick, Jeffrey A.

    2016-01-01

    Mercury is a highly toxic heavy metal and the ability of the neurotoxin methylmercury to biomagnify in the food chain is a serious concern for both public and environmental health globally. Because thousands of tons of mercury are released into the environment each year, remediation strategies are urgently needed and prompted this study. To facilitate remediation of both organic and inorganic forms of mercury, Escherichia coli was engineered to harbor a subset of genes (merRTPAB) from the mercury resistance operon. Protein products of the mer operon enable transport of mercury into the cell, cleavage of organic C-Hg bonds, and subsequent reduction of ionic mercury to the less toxic elemental form, Hg(0). E. coli containing merRTPAB was then encapsulated in silica beads resulting in a biological-based filtration material. Performing encapsulation in aerated mineral oil yielded silica beads that were smooth, spherical, and similar in diameter. Following encapsulation, E. coli containing merRTPAB retained the ability to degrade methylmercury and performed similarly to non-encapsulated cells. Due to the versatility of both the engineered mercury resistant strain and silica bead technology, this study provides a strong foundation for use of the resulting biological-based filtration material for methylmercury remediation. PMID:26761437

  12. Effects of Maternally-Transferred Methylmercury on Stress Physiology in Northern Water Snake (Nerodia sipedon) Neonates.

    PubMed

    Cusaac, J Patrick W; Kremer, Victoria; Wright, Raymond; Henry, Cassandra; Otter, Ryan R; Bailey, Frank C

    2016-06-01

    Biomagnification of methylmercury in aquatic systems can cause elevated tissue mercury (Hg) and physiological stress in top predators. Mercury is known to affect stress hormone levels in mammals, birds and fish. In this study, the effects of maternally-transferred methylmercury on the stress physiology of Northern Water Snake (Nerodia sipedon) neonates were tested. Gravid females were dosed via force-fed capsules during late gestation with 0, 0.01, or 10 µg methylmercury per gram of body mass. Plasma corticosterone levels and leukocyte differentials were analyzed in baseline and confinement-stressed neonates from all dose levels. Neither Hg nor confinement stress had a significant effect on leukocyte differentials nor was Hg related to corticosterone levels. However, stress group neonates showed lower heterophil/lymphocyte ratios and this study was the first to show that neonate N. sipedon can upregulate CORT in response to stress. These results indicate that N. sipedon may be somewhat tolerant to Hg contamination. PMID:26886428

  13. Assessment of neurotoxic effects and brain region distribution in rat offspring prenatally co-exposed to low doses of BDE-99 and methylmercury.

    PubMed

    Zhao, Wenchang; Cheng, Jinping; Gu, Jinmin; Liu, Yuanyuan; Fujimura, Masatake; Wang, Wenhua

    2014-10-01

    Exposure to polybrominated diphenyl ether (PDBE) and methylmercury (MeHg) can occur simultaneously as both contaminants are found in the same food sources, especially fish, seafood, marine mammals and milk. The aim of this study was to assess the effects of exposure to low levels of MeHg (2.0 μg mL(-1) in drinking water) and BDE-99 (0.2 mg kg(-1) d(-1)) from gestational day 6 to postnatal day (PND) 21, alone and in combination, on neurobehavioral development and redox responses in offspring. The present study demonstrated an interaction due to co-exposure with low doses of MeHg and BDE-99 enhanced developmental neurotoxic effects. These effects were manifested as the delayed appearance of negative geotaxis reflexes, impaired motor coordination, and induction of oxidative stress in the cerebellum. In particular, the cerebellum may be a sensitive target for combined MeHg and BDE-99 toxicity. The neurotoxicity of low dose MeHg was exacerbated by the presence of low dose of BDE-99. It is concluded that prenatal co-exposure to MeHg and BDE-99 causes oxidative stress in the cerebellum of offspring by altering the activity of different antioxidant enzymes and producing free radicals. Hg retention was not affected by co-exposure to BDE-99. However, MeHg co-exposure seemed to increase BDE-99 concentrations in selected brain regions in pups compared to pups exposed to BDE-99 only. These results showed that the adverse effects following prenatal co-exposure to MeHg and BDE-99 were associated with tissue concentrations very close to the current human body burden of this persistent bioaccumulative compound. PMID:25048903

  14. Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter.

    PubMed

    Fleck, Jacob A; Gill, Gary; Bergamaschi, Brian A; Kraus, Tamara E C; Downing, Bryan D; Alpers, Charles N

    2014-06-15

    Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercury (Hg) cycling. This study investigated changes in MeHg concentration, DOM concentration, and the optical signature of DOM caused by light exposure in a controlled field-based experiment using water samples collected from wetlands and rice fields. Filtered water from all sites showed a marked loss in MeHg concentration after light exposure. The rate of photodemethylation was 7.5×10(-3)m(2)mol(-1) (s.d. 3.5×10(-3)) across all sites despite marked differences in DOM concentration and composition. Light exposure also caused changes in the optical signature of the DOM despite there being no change in DOM concentration, indicating specific structures within the DOM were affected by light exposure at different rates. MeHg concentrations were related to optical signatures of labile DOM whereas the percent loss of MeHg was related to optical signatures of less labile, humic DOM. Relationships between the loss of MeHg and specific areas of the DOM optical signature indicated that aromatic and quinoid structures within the DOM were the likely contributors to MeHg degradation, perhaps within the sphere of the Hg-DOM bond. Because MeHg photodegradation rates are relatively constant across freshwater habitats with natural Hg-DOM ratios, physical characteristics such as shading and hydrologic residence time largely determine the relative importance of photolytic processes on the MeHg budget in these mixed vegetated and open-water systems. PMID:23642571

  15. Concurrent photolytic degradation of aqueous methylmercury and dissolved organic matter

    USGS Publications Warehouse

    Fleck, Jacob A.; Gill, Gary W.; Bergamaschi, Brian A.; Kraus, Tamara E.C.; Downing, Bryan D.; Alpers, Charles N.

    2014-01-01

    Monomethyl mercury (MeHg) is a potent neurotoxin that threatens ecosystem viability and human health. In aquatic systems, the photolytic degradation of MeHg (photodemethylation) is an important component of the MeHg cycle. Dissolved organic matter (DOM) is also affected by exposure to solar radiation (light exposure) leading to changes in DOM composition that can affect its role in overall mercury (Hg) cycling. This study investigated changes in MeHg concentration, DOM concentration, and the optical signature of DOM caused by light exposure in a controlled field-based experiment using water samples collected from wetlands and rice fields. Filtered water from all sites showed a marked loss in MeHg concentration after light exposure. The rate of photodemethylation was 7.5 × 10-3 m2 mol-1 (s.d. 3.5 × 10-3) across all sites despite marked differences in DOM concentration and composition. Light exposure also caused changes in the optical signature of the DOM despite there being no change in DOM concentration, indicating specific structures within the DOM were affected by light exposure at different rates. MeHg concentrations were related to optical signatures of labile DOM whereas the percent loss of MeHg was related to optical signatures of less labile, humic DOM. Relationships between the loss of MeHg and specific areas of the DOM optical signature indicated that aromatic and quinoid structures within the DOM were the likely contributors to MeHg degradation, perhaps within the sphere of the Hg-DOM bond. Because MeHg photodegradation rates are relatively constant across freshwater habitats with natural Hg–DOM ratios, physical characteristics such as shading and hydrologic residence time largely determine the relative importance of photolytic processes on the MeHg budget in these mixed vegetated and open-water systems.

  16. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds.

    PubMed

    Davis, J A; Looker, R E; Yee, D; Marvin-Di Pasquale, M; Grenier, J L; Austin, C M; McKee, L J; Greenfield, B K; Brodberg, R; Blum, J D

    2012-11-01

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  17. Reducing Methylmercury Accumulation in the Food Webs of San Francisco Bay and Its Local Watersheds

    PubMed Central

    Davis, J.A.; Looker, R.E.; Yee, D.; Marvin-DiPasquale, M.; Grenier, J.L.; Austin, C.M.; McKee, L.J.; Greenfield, B.K.; Brodberg, R.; Blum, J.D.

    2013-01-01

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  18. Reducing methylmercury accumulation in the food webs of San Francisco Bay and its local watersheds

    SciTech Connect

    Davis, J.A.; Looker, R.E.; Yee, D.; Marvin-Di Pasquale, M.; Austin, C.M.; McKee, L.J.; Greenfield, B.K.; Brodberg, R.; Blum, J.D.

    2012-11-15

    San Francisco Bay (California, USA) and its local watersheds present an interesting case study in estuarine mercury (Hg) contamination. This review focuses on the most promising avenues for attempting to reduce methylmercury (MeHg) contamination in Bay Area aquatic food webs and identifying the scientific information that is most urgently needed to support these efforts. Concern for human exposure to MeHg in the region has led to advisories for consumption of sport fish. Striped bass from the Bay have the highest average Hg concentration measured for this species in USA estuaries, and this degree of contamination has been constant for the past 40 years. Similarly, largemouth bass in some Bay Area reservoirs have some of the highest Hg concentrations observed in the entire US. Bay Area wildlife, particularly birds, face potential impacts to reproduction based on Hg concentrations in the tissues of several Bay species. Source control of Hg is one of the primary possible approaches for reducing MeHg accumulation in Bay Area aquatic food webs. Recent findings (particularly Hg isotope measurements) indicate that the decades-long residence time of particle-associated Hg in the Bay is sufficient to allow significant conversion of even the insoluble forms of Hg into MeHg. Past inputs have been thoroughly mixed throughout this shallow and dynamic estuary. The large pool of Hg already present in the ecosystem dominates the fraction converted to MeHg and accumulating in the food web. Consequently, decreasing external Hg inputs can be expected to reduce MeHg in the food web, but it will likely take many decades to centuries before those reductions are achieved. Extensive efforts to reduce loads from the largest Hg mining source (the historic New Almaden mining district) are underway. Hg is spread widely across the urban landscape, but there are a number of key sources, source areas, and pathways that provide opportunities to capture larger quantities of Hg and reduce loads

  19. METHYLMERCURY IMPAIRS NEURONAL DIFFERENTIATION BY ALTERING NEUROTROPHIN SIGNALING.

    EPA Science Inventory

    In previous in vivo studies, we observed that developmental exposure to CH3Hg can alter neocortical morphology and neurotrophin signaling. Using primed PC12 cells as a model system for neuronal differentiation, we examined the hypothesis that the developmental effects of CH3Hg ma...

  20. Superoxide anion radical (O2(-)) degrades methylmercury to inorganic mercury in human astrocytoma cell line (CCF-STTG1).

    PubMed

    Mailloux, Ryan J; Yumvihoze, Emmanuel; Chan, Hing Man

    2015-09-01

    Methylmercury (MeHg) is a global pollutant that is affecting the health of millions of people worldwide. However, the mechanism of MeHg toxicity still remains somewhat elusive and there is no treatment. It has been known for some time that MeHg can be progressively converted to inorganic mercury (iHg) in various tissues including the brain. Recent work has suggested that cleavage of the carbon-metal bond in MeHg in a biological environment is facilitated by reactive oxygen species (ROS). However, the oxyradical species that actually mediates this process has not been identified. Here, we provide evidence that superoxide anion radical (O2(-)) can convert MeHg to iHg. The calculated second-order rate constant for the degradation of 1μM MeHg by O2(-) generated by xanthine/xanthine oxidase was calculated to be 2×10(5)M(-1)s(-1). We were also able to show that this bioconversion can proceed in intact CCF-STTG1 human astrocytoma cells exposed to paraquat (PQ), a O2(-) generating viologen. Notably, exposure of cells to increasing amounts of PQ led to a dose dependent increase in both MeHg and iHg. Indeed, a 24h exposure to 500μM PQ induced a ∼13-fold and ∼18-fold increase in intracellular MeHg and iHg respectively. These effects were inhibited by superoxide dismutase mimetic MnTBAP. In addition, we also observed that a 24h exposure to a biologically relevant concentration of MeHg (1μM) did not induce cell death, oxidative stress, or even changes in cellular O2(-) and H2O2. However, co-exposure to PQ enhanced MeHg toxicity which was associated with a robust increase in cell death and oxidative stress. Collectively our results show that O2(-) can bioconvert MeHg to iHg in vitro and in intact cells exposed to conditions that simulate high intracellular O2(-) production. In addition, we show for the first time that O2(-) mediated degradation of MeHg to iHg enhances the toxicity of MeHg by facilitating an accumulation of both MeHg and iHg in the intracellular

  1. Bioaccessibility and bioavailability of methylmercury from seafood commonly consumed in North America: In vitro and epidemiological studies.

    PubMed

    Siedlikowski, Maia; Bradley, Mark; Kubow, Stan; Goodrich, Jaclyn M; Franzblau, Alfred; Basu, Niladri

    2016-08-01

    Methylmercury (MeHg) is a global contaminant of concern and human exposures are largely realized via seafood consumption. While it is assumed that 95-100% of the ingested MeHg from seafood reaches systemic circulation, recent in vitro studies have yielded results to suggest otherwise. Of the published studies to have characterized the bioaccessibility or bioavailability of MeHg from seafood, only a handful of seafood species have been characterized, there exists tremendous variability in data within and across species, few species of relevance to North America have been studied, and none of the in vitro studies have adapted results to an epidemiology study. The objective of the current study was two-fold: (a) to characterize in vitro MeHg bioaccessibility and bioavailability from ten commonly consumed types of seafood in North America; and (b) to apply the bioaccessibility and bioavailability data from the in vitro study to an existing human MeHg exposure assessment study. Raw seafood samples (cod, crab, halibut, salmon, scallop, shrimp, tilapia, and three tuna types: canned light, canned white, fresh) were purchased in Montreal and their MeHg concentrations generally overlapped with values reported elsewhere. The bioaccessibility of MeHg from these samples ranged from 50.1±19.2 (canned white tuna) to 100% (shrimp and scallop) of the amount measured in the raw undigested sample. The bioavailability of MeHg from these samples ranged from 29.3±10.4 (crab) to 67.4±9.7% (salmon) of the value measured in the raw undigested sample. There were significant correlations between the initial MeHg concentration in seafood with the percent of that Hg that was bioaccessible (r=-0.476) and bioavailable (r=-0.294). When the in vitro data were applied to an existing MeHg exposure assessment study, the estimated amount of MeHg absorbed into systemic circulation decreased by 25% and 42% when considering bioaccessibility and bioavailability, respectively. When the in vitro data

  2. An Immunofluorescence Assay to Detect Urediniospores of the Soybean Rust Pathogen, Phakopsora pachyrhizi

    Technology Transfer Automated Retrieval System (TEKTRAN)

    An indirect immunofluorescence spore assay (IFSA) was developed to detect urediniospores of Phakopsora pachyrhizi, utilizing rabbit polyclonal antisera produced in response to intact non-germinated (SBR1A) or germinated (SBR2) urediniospores of P. pachyrhizi. Both antisera were specific to Phakopso...

  3. DETECTION AND IDENTIFICATION OF 'GIARDIA' CYSTS USING IMMUNOFLUORESCENCE AND PHASE CONTRAST MICROSCOPY

    EPA Science Inventory

    Detection and identification of Giardia cysts in water samples has been improved by the development of an immunofluorescent method that specifically stains Giardia cysts bright green and allows their easy detection against a black background. The report discusses aspects of the m...

  4. Immunofluorescent localization of adhesive glycoproteins in resting and thrombin-stimulated platelets.

    PubMed Central

    Wencel-Drake, J. D.; Plow, E. F.; Zimmerman, T. S.; Painter, R. G.; Ginsberg, M. H.

    1984-01-01

    The distribution and transport of thrombospondin (TSP), fibrinogen (Fbg), fibronectin (Fn), and Factor VIII-related antigen (VIII:RAg) in resting and thrombin-stimulated platelets was investigated by immunofluorescence microscopy. In resting intact cells, little surface staining was seen for these proteins. In permeable resting cells, punctate staining similar to that reported for platelet factor 4 was observed. Double-label immunofluorescence staining for Fbg and either beta-thromboglobulin (beta TG), TSP, or Fn demonstrated co-localization, indicating their presence in the same intracellular structures. VIII:RAg showed general co-localization; however, the staining was finer, suggesting a possible differential intragranular localization. Thrombin stimulation induced the appearance of larger (approximately 0.5 mu) immunofluorescent masses of these proteins. In thrombin-stimulated cells, co-localization of all proteins in these masses was observed by double label immunofluorescence. Thus, TSP, Fbg, Fn, and beta TG are localized in the same structure in resting cells. Thrombin stimulates formation of common larger masses of these proteins prior to their release, suggesting that they reach the cell surface through a common intermediate. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 PMID:6232852

  5. Periodic Acid-Schiff Staining Parallels the Immunoreactivity Seen By Direct Immunofluorescence in Autoimmune Skin Diseases

    PubMed Central

    Abreu Velez, Ana Maria; Upegui Zapata, Yulieth Alexandra; Howard, Michael S

    2016-01-01

    Background: In many countries and laboratories, techniques such as direct immunofluorescence (DIF) are not available for the diagnosis of skin diseases. Thus, these laboratories are limited in the full diagnoses of autoimmune skin diseases, vasculitis, and rheumatologic diseases. In our experience with these diseases and the patient's skin biopsies, we have noted a positive correlation between periodic acid-Schiff (PAS) staining and immunofluorescence patterns; however, these were just empiric observations. In the current study, we aim to confirm these observations, given the concept that the majority of autoantibodies are glycoproteins and should thus be recognized by PAS staining. Aims: To compare direct immunofluorescent and PAS staining, in multiple autoimmune diseases that are known to exhibit specific direct immunofluorescent patterns. Materials and Methods: We studied multiple autoimmune skin diseases: Five cases of bullous pemphigoid, five cases of pemphigus vulgaris, ten cases of cutaneous lupus, ten cases of autoimmune vasculitis, ten cases of lichen planus (LP), and five cases of cutaneous drug reactions (including one case of erythema multiforme). In addition, we utilized 45 normal skin control specimens from plastic surgery reductions. Results: We found a 98% positive correlation between DIF and PAS staining patterns over all the disease samples. Conclusion: We recommend that laboratories without access to DIF always perform PAS staining in addition to hematoxylin and eosin (H&E) staining, for a review of the reactivity pattern. PMID:27114972

  6. BLIND TRIALS EVALUATING IN VITRO INFECTIVITY OF CRYPTOSPORIDIUM PARVUM OOCYSTS USING CELL CULTURE IMMUNOFLUORESCENCE

    EPA Science Inventory

    An optimized cell culture-immunofluorescence (IFA) procedure, using the HCT-8 cell line, was evaluated in 'blind' trials to determine the sensitivity and reproducibility for measuring infectivity of flow cytometry prepared inocula of C. parvum oocysts. In separate trials, suspens...

  7. Detection of Specific Strains and Variants of Streptococcus cremoris in Mixed Cultures by Immunofluorescence

    PubMed Central

    Hugenholtz, Jeroen; Veldkamp, Hans; Konings, Wil N.

    1987-01-01

    Antisera against four different strains of Streptococcus cremoris were raised by injecting rabbits with washed suspensions of whole cells. These antisera interacted specifically with the corresponding strain in a mixture of up to nine different S. cremoris strains. The antisera could be used for analyzing the composition of mixed cultures containing these strains by immunofluorescence. Competition experiments were performed in batch and continuous cultures under amino acid limitation. A bacteriophage-sensitive variant of S. cremoris SK11 (SK1128) could be distinguished from a bacteriophage-resistant variant (SK1143) by the same immunofluorescence technique. The competition between the two variants and the stability of both variants in pure cultures were followed with the specific antibodies. Antibodies against the purified proteolytic system of S. cremoris Wg2 were used to determine the presence of proteases by immunofluorescence in several S. cremoris strains under different culture conditions. The described immunofluorescence methods can be used to analyze complex mixed starter cultures common in the dairy industry as the strains and variants present in these mixtures can be recognized microscopically. Images PMID:16347256

  8. Immunofluorescence testing in the diagnosis of autoimmune blistering diseases: overview of 10-year experience*

    PubMed Central

    Arbache, Samia Trigo; Nogueira, Tarsila Gasparotto; Delgado, Lívia; Miyamoto, Denise; Aoki, Valéria

    2014-01-01

    BACKGROUND Immunofluorescence testing is an important tool for diagnosing blistering diseases. OBJECTIVE To characterize the immunofluorescence findings in patients diagnosed with autoimmune blistering skin diseases. METHODS We retrospectively analyzed immunofluorescence results encompassing a 10-year period. RESULTS 421 patients were included and divided into 2 groups: group 1- intraepidermal blistering diseases (n=277) and 2- subepidermal blistering diseases (n=144). For group 1, positive DIF findings demonstrated: predominance of IgG intercellular staining (ICS) and C3 for pemphigus foliaceus-PF (94% and 73% respectively), pemphigus vulgaris-PV (91.5%-79.5%) and paraneoplastic pemphigus-PNP (66%-33%); ICS IgA in 100% of IgA pemphigus cases, and IgG deposits in the basement membrane zone (BMZ) along with ICS in one Hailey-Hailey patient. The IIF findings revealed mean titers of 1:2.560 for PV and 1:1.280 for PF. For paraneoplastic pemphigus, IIF was positive in 2 out of 3 cases with rat bladder substrate. In group 2, positive DIF findings included multiple deposits at basement membrane zone for epidermolysis bullosa acquisita-EBA (C3-89%,IgG-79%,IgA-47%,IgM-21%) mucous membrane pemphigoid-MMP (C3,IgG,IgA,IgM-80%) and bullous pemphigoid-BP (C3-91%,IgG-39%,IgA-11%,IgM-6%), and IgA at basement membrane zone for IgA linear disease (99%) and dermatitis herpetiformis-DH (dermal papillae in 84.6%). For lichen planus pemphigoides, there was C3 (100%) and IgG (50%) deposition at basement membrane zone. indirect immunofluorescence positive findings revealed basement membrane zone IgG deposits in 46% of BP patients, 50% for EBA, 15% for IgA linear dermatosis and 50% for LPP. Indirect immunofluorescence positive results were higher for BP and EBA with Salt-Split skin substrate. CONCLUSION Our results confirmed the importance of immunofluorescence assays in diagnosing autoimmune blistering diseases, and higher sensitivity for indirect immunofluorescence when Salt-split skin

  9. Prenatal Exposures to Environmental Chemicals and Children's Neurodevelopment: An Update

    PubMed Central

    2013-01-01

    This review surveys the recent literature on the neurodevelopmental impacts of chemical exposures during pregnancy. The review focuses primarily on chemicals of recent concern, including phthalates, bisphenol-A, polybrominated diphenyl ethers, and perfluorinated compounds, but also addresses chemicals with longer histories of investigation, including air pollutants, lead, methylmercury, manganese, arsenic, and organophosphate pesticides. For some chemicals of more recent concern, the available literature does not yet afford strong conclusions about neurodevelopment toxicity. In such cases, points of disagreement among studies are identified and suggestions provided for approaches to resolution of the inconsistencies, including greater standardization of methods for expressing exposure and assessing outcomes. PMID:23515885

  10. The distribution of, and relation among, mercury and methylmercury, organic carbon, carbonate, nitrogen and phosphorus, in periphyton of the south florida ecosystem

    USGS Publications Warehouse

    Simon, N.S.; Spencer, R.; Cox, T.

    1999-01-01

    Periphyton samples from Water Conservation Areas, Big Cypress National Preserve, and Everglades National Park in south Florida were analyzed for concentrations of total mercury, methylmercury, nitrogen, phosphorus, organic carbon, and inorganic carbon. Concentrations of total mercury in periphyton decrease slightly along a gradient from north-to-south. Both total mercury and methylmercury are positively correlated with organic carbon, nitrogen and phosphorus in periphyton. In horizontal sections of periphyton mats, total mercury concentrations tend to be largest at the tops and bottoms of the mats. Methylmercury concentrations tend to be the largest near the bottom of mats. These localized elevated concentrations of methylmercury suggest that there are "hot spots" of methylmercury in periphyton. ?? 1999 OPA (Overseas Publishers Association) N.V. Published by license under the Gordon and Breach Science Publishers imprint.

  11. Organ-specific accumulation, transportation, and elimination of methylmercury and inorganic mercury in a low Hg accumulating fish.

    PubMed

    Peng, Xiaoyan; Liu, Fengjie; Wang, Wen-Xiong

    2016-08-01

    Low mercury (Hg) concentrations down to several nanograms Hg per gram of wet tissue are documented in certain fish species such as herbivorous fish, and the underlying mechanisms remain speculative. In the present study, bioaccumulation and depuration patterns of inorganic Hg(II) and methylmercury (MeHg) in a herbivorous rabbitfish Siganus canaliculatus were investigated at organ and subcellular levels following waterborne or dietary exposures. The results showed that the efflux rate constants of Hg(II) and MeHg were 0.104 d(-1) and 0.024 d(-1) , respectively, and are probably the highest rate constants recorded in fish thus far. The dietary MeHg assimilation efficiency (68%) was much lower than those in other fish species (∼90%). The predominant distribution of MeHg in fish muscle was attributable to negligible elimination of MeHg from muscle (< 0) and efficient elimination of MeHg from gills (0.12 d(-1) ), liver (0.17 d(-1) ), and intestine (0.20 d(-1) ), as well as efficient transportation of MeHg from other organs into muscle. In contrast, Hg(II) was much more slowly distributed into muscle but was efficiently eliminated by the intestine (0.13 d(-1) ). Subcellular distribution indicated that some specific membrane proteins in muscle were the primary binding pools for MeHg, and both metallothionein-like proteins and Hg-rich granules were the important components in eliminating both MeHg and Hg(II). Overall, the present study's results suggest that the low tissue Hg concentration in the rabbitfish was partly explained by its unique biokinetics. Environ Toxicol Chem 2016;35:2074-2083. © 2016 SETAC. PMID:26756981

  12. Mercury loading and methylmercury production and cycling in high-altitude lakes from the Western United States

    USGS Publications Warehouse

    Krabbenhoft, David P.; Olson, Mark L.; DeWild, John F.; Clow, David W.; Striegl, Rob; Dornblaser, Mark M.; Van Metre, Peter C.

    2002-01-01

    Studies worldwide have shown that mercury (Hg) is a ubiquitous contaminant, reaching even the most remote environments such as high-altitude lakes via atmospheric pathways. However, very few studies have been conducted to assess Hg contamination levels of these systems. We sampled 90 mid-latitude, high-altitude lakes from seven national parks in the western United States during a four-week period in September 1999. In addition to the synoptic survey, routine monitoring and experimental studies were conducted at one of the lakes (Mills Lake) to quantify MeHg fluxrates and important process rates such as photo-demethylation. Results show that overall, high-altitude lakes have low total mercury (HgT) and methylmercury (MeHg) levels (1.07 and 0.05 ng L-1, respectively), but a very good correlation of Hg to MeHg (r2= 0.82) suggests inorganic Hg(II) loading is a primary controlling factor of MeHg levels in dilute mountain lakes. Positive correlations were also observed for dissolved organic carbon (DOC) and both Hg and MeHg, although to a much lesser degree. Levels of MeHg were similar among the seven national parks, with the exception of Glacier National Park where lowerconcentrations were observed (0.02 ng L-1), and appear to be related to naturally elevated pH values there. Measured rates ofMeHg photo-degradation at Mills Lake were quite fast, and this process was of equal importance to sedimentation and stream flow for removing MeHg. Enhanced rates of photo-demethylation are likely an important reason why high-altitude lakes, with typically high water clarity and sunlight exposure, are low in MeHg.

  13. Evaluation of biochars and activated carbons for in situ remediation of sediments impacted with organics, mercury, and methylmercury.

    PubMed

    Gomez-Eyles, Jose L; Yupanqui, Carmen; Beckingham, Barbara; Riedel, Georgia; Gilmour, Cynthia; Ghosh, Upal

    2013-12-01

    In situ amendment of activated carbon (AC) to sediments can effectively reduce the bioavailability of hydrophobic organic contaminants. While biochars have been suggested as low-cost and sustainable alternatives to ACs, there are few comparative sorption data especially for mercury (Hg) and methylmercury (MeHg) at the low porewater concentrations in sediments. Here we compare the ability of a wide range of commercially available and laboratory synthesized ACs and biochars to sorb PAHs, PCBs, DDTs, inorganic Hg, and MeHg at environmentally relevant concentrations. Compared to natural organic matter, sorption capacity for most organic compounds was at least 1-2 orders of magnitude higher for unactivated biochars and 3-4 orders of magnitude higher for ACs which translated to sediment porewater PCB concentration reductions of 18-80% for unactivated biochars, and >99% for ACs with 5% by weight amendment to sediment. Steam activated carbons were more effective than biochars in Hg sorption and translated to modeled porewater Hg reduction in the range of 94-98% for sediments with low native Kd and 31-73% for sediments with high native Kd values for Hg. Unactivated biochars were as effective as the steam activated carbons for MeHg sorption. Predicted reductions of porewater MeHg were 73-92% for sediments with low native Kd and 57-86% for sediment with high native K(d). ACs with high surface areas therefore are likely to be effective in reducing porewater concentrations of organics, Hg, and MeHg in impacted sediments. Unactivated biochars had limited effectiveness for organics and Hg but can be considered when MeHg exposure is the primary concern. PMID:24168448

  14. Effects of trophic poisoning with methylmercury on the appetitive elements of the agonistic sequence in fighting-fish (Betta splendens).

    PubMed

    Gouveia, Amauri; de Oliveira, Caio Maximino; Romão, Cynthia Ferreira; de Brito, Thiago Marques; Ventura, Dora Fix

    2007-11-01

    The aggressive display in Betta splendens is particularly prominent, and vital to its adaptation to the environment. Methylmercury is an organic variation of Hg that presents particularly pronounced neuro-behavioral effects. The present experiments aim to test the effect of acute and chronic poisoning with methylmercury on the display in Bettas. The animals were poisoned by trophic means in both experiments (16 ug/kg in acute poisoning; 16 ug/kg/day for chronic poisoning), and tested in agonistic pairs. The total frequency of the display was recorded, analyzing the topography of the agonistic response. The methylmercury seems to present a dose- and detoxification-dependent effect on these responses, with a more pronounced effect on motivity in acute poisoning and on emotionality in the chronic poisoning. It is possible that this effect could be mediated by alteration in the mono-amino-oxidase systems. PMID:17992970

  15. Trace-elements, methylmercury and metallothionein levels in Magellanic penguin (Spheniscus magellanicus) found stranded on the Southern Brazilian coast.

    PubMed

    Kehrig, Helena A; Hauser-Davis, Rachel A; Seixas, Tércia G; Fillmann, Gilberto

    2015-07-15

    Magellanic penguins have been reported as good biomonitors for several types of pollutants, including trace-elements. In this context, selenium (Se), total mercury, methylmercury, inorganic mercury (Hg(inorg)), cadmium (Cd) and lead (Pb), as well as metallothionein (MT) levels, were evaluated in the feathers, liver and kidney of juvenile Magellanic penguins found stranded along the coast of Southern Brazil. The highest concentrations of all trace-elements and methylmercury were found in internal organs. Concentrations of Cd and Se in feathers were extremely low in comparison with their concentrations in soft tissues. The results showed that both Se and MT are involved in the detoxification of trace-elements (Cd, Pb and Hg(inorg)) since statistically significant relationships were found in liver. Conversely, hepatic Se was shown to be the only detoxifying agent for methylmercury. PMID:25960272

  16. The Nicotine-Evoked Locomotor Response: A Behavioral Paradigm for Toxicity Screening in Zebrafish (Danio rerio) Embryos and Eleutheroembryos Exposed to Methylmercury

    PubMed Central

    Mora-Zamorano, Francisco X.; Svoboda, Kurt R.; Carvan, Michael J.

    2016-01-01

    This study is an adaptation of the nicotine-evoked locomotor response (NLR) assay, which was originally utilized for phenotype-based neurotoxicity screening in zebrafish embryos. Zebrafish embryos do not exhibit spontaneous swimming until roughly 4 days post-fertilization (dpf), however, a robust swimming response can be induced as early as 36 hours post-fertilization (hpf) by means of acute nicotine exposure (30–240μM). Here, the NLR was tested as a tool for early detection of locomotor phenotypes in 36, 48 and 72 hpf mutant zebrafish embryos of the non-touch-responsive maco strain; this assay successfully discriminated mutant embryos from their non-mutant siblings. Then, methylmercury (MeHg) was used as a proof-of-concept neurotoxicant to test the effectiveness of the NLR assay as a screening tool in toxicology. The locomotor effects of MeHg were evaluated in 6 dpf wild type eleutheroembryos exposed to waterborne MeHg (0, 0.01, 0.03 and 0.1μM). Afterwards, the NLR assay was tested in 48 hpf embryos subjected to the same MeHg exposure regimes. Embryos exposed to 0.01 and 0.03μM of MeHg exhibited significant increases in locomotion in both scenarios. These findings suggest that similar locomotor phenotypes observed in free swimming fish can be detected as early as 48 hpf, when locomotion is induced with nicotine. PMID:27123921

  17. Microsolvation of methylmercury: structures, energies, bonding and NMR constants ((199)Hg, (13)C and (17)O).

    PubMed

    Flórez, Edison; Maldonado, Alejandro F; Aucar, Gustavo A; David, Jorge; Restrepo, Albeiro

    2016-01-21

    Hartree-Fock (HF) and second order perturbation theory (MP2) calculations within the scalar and full relativistic frames were carried out in order to determine the equilibrium geometries and interaction energies between cationic methylmercury (CH3Hg(+)) and up to three water molecules. A total of nine structures were obtained. Bonding properties were analyzed using the Quantum Theory of Atoms In Molecules (QTAIM). The analyses of the topology of electron densities reveal that all structures exhibit a partially covalent HgO interaction between methylmercury and one water molecule. Consideration of additional water molecules suggests that they solvate the (CH3HgOH2)(+) unit. Nuclear magnetic shielding constants σ((199)Hg), σ((13)C) and σ((17)O), as well as indirect spin-spin coupling constants J((199)Hg-(13)C), J((199)Hg-(17)O) and J((13)C-(17)O), were calculated for each one of the geometries. Thermodynamic stability and the values of NMR constants correlate with the ability of the system to directly coordinate oxygen atoms of water molecules to the mercury atom in methylmercury and with the formation of hydrogen bonds among solvating water molecules. Relativistic effects account for 11% on σ((13)C) and 14% on σ((17)O), which is due to the presence of Hg (heavy atom on light atom, HALA effect), while the relativistic effects on σ((199)Hg) are close to 50% (heavy atom on heavy atom itself, HAHA effect). J-coupling constants are highly influenced by relativity when mercury is involved as in J((199)Hg-(13)C) and J((199)Hg-(17)O). On the other hand, our results show that the values of NMR constants for carbon and oxygen, atoms which are connected through mercury (C-HgO), are highly correlated and are greatly influenced by the presence of water molecules. Water molecules introduce additional electronic effects to the relativistic effects due to the mercury atom. PMID:26670708

  18. Ultrastructure of kidney of ducks exposed to methylmercury, lead and cadmium in combination.

    PubMed

    Rao, P V; Jordan, S A; Bhatnagar, M K

    1989-01-01

    Ultrastructural alterations in the kidneys of Pekin ducks exposed to various combinations of methylmercury chloride (MeHgCl), lead acetate (PbAC) and cadmium chloride (CdCl2 for 12 weeks were studied. Eight groups (Gr), each consisting of 6 female ducks, were fed diets containing no heavy metals (control), 8 mg of methylmercury chloride (MeHgCl)/kg of feed (GrII), 80 mg of lead acetate (PbAC)/kg of feed (GrIII), 80 mg of cadmium chloride (CdCl2)/kg of feed (GrIV), 8 mg of MeHgCl + 80 mg of PbAC/kg of feed (GrV), 8 mg of MeHgCl + 80 mg of CdCl2/kg of feed (GrVI), 80 mg of PbAC + 80 mg of CdCl2/kg of feed (GrVII), and 8 mg of MeHgCl + 80 mg of PbAC + 80 mg of CdCl2/kg of feed (GrVIII). Renal corpuscles of the ducks treated with methylmercury (MdHg), lead (Pb), the cadmium (Cd), either alone or in two way combinations exhibited minor ultrastructural changes. The thickness of the glomerular basement membrane was significantly different from control only in Grs II, IV, V and VI. Crystallization of granules in the juxtaglomerular cells was also observed in Cd and Pb treated birds. Administration of the three metals in combination caused marked changes in podocytes with fusion of secondary processes and no pedicle differentiation. The proximal tubule cells approximately (PT) accumulated lipid droplets, lysosomal bodies and membrane bound vacuoles in methylmercury treated birds. Lead exposed birds had a large number of secondary lysosomes and swollen mitochondria in PT cells. Cadmium administration caused degenerative changes in PT cells which included accumulation of lysosomal bodies containing degenerating organelles, lipid droplets and vacuoles containing myelin figures. Marked degenerative changes in PT cells and interstitial fibrosis was prominent when cadmium was concomitantly administered with the other metals. Concurrent administration of all three metals caused enhancement of degenerative changes in proximal tubule cells and collecting duct cells. These

  19. Ultrastructure of kidney of ducks exposed to methylmercury, lead and cadmium in combination

    SciTech Connect

    Rao, P.V.; Jordan, S.A.; Bhatnagar, M.K.

    1989-01-01

    Ultrastructural alterations in the kidneys of Pekin ducks exposed to various combinations of methylmercury chloride (MeHgCl), lead acetate (PbAC) and cadmium chloride (CdCl2) for 12 weeks were studied. Eight groups (Gr), each consisting of 6 female ducks, were fed diets containing no heavy metals (control), 8 mg of methylmercury chloride (MeHgCl)/kg of feed (GrII), 80 mg of lead acetate (PbAC)/kg of feed (GrIII), 80 mg of cadmium chloride (CdCl2)/kg of feed (GrIV), 8 mg of MeHgCl + 80 mg of PbAC/kg of feed (GrV), 8 mg of MeHgCl + 80 mg of CdCl2/kg of feed (GrVI), 80 mg of PbAC + 80 mg of CdCl2/kg of feed (GrVII), and 8 mg of MeHgCl + 80 mg of PbAC + 80 mg of CdCl2/kg of feed (GrVIII). Renal corpuscles of the ducks treated with methylmercury (MdHg), lead (Pb), the cadmium (Cd), either alone or in two way combinations exhibited minor ultrastructural changes. The thickness of the glomerular basement membrane was significantly different from control only in Grs II, IV, V and VI. Crystallization of granules in the juxtaglomerular cells was also observed in Cd and Pb treated birds. Administration of the three metals in combination caused marked changes in podocytes with fusion of secondary processes and no pedicle differentiation. The proximal tubule cells approximately (PT) accumulated lipid droplets, lysosomal bodies and membrane bound vacuoles in methylmercury treated birds. Lead exposed birds had a large number of secondary lysosomes and swollen mitochondria in PT cells. Cadmium administration caused degenerative changes in PT cells which included accumulation of lysosomal bodies containing degenerating organelles, lipid droplets and vacuoles containing myelin figures. Marked degenerative changes in PT cells and interstitial fibrosis was prominent when cadmium was concomitantly administered with the other metals.

  20. Synthesis of an imprinted polymer for the determination of methylmercury in marine products.

    PubMed

    Rodríguez-Fernández, Roi; Peña-Vázquez, Elena; Bermejo-Barrera, Pilar

    2015-11-01

    A molecularly imprinted polymer was synthesized using the precipitation method with methylmercury chloride as the template, phenobarbital as ligand, methacrylic acid (MMA) as monomer, and ethylene glycoldimethacrylate (EDMA) as cross-linking agent. The MIP was characterized using elemental analysis, infrared spectroscopy, energy dispersive X-ray fluorescence and scanning electron microscopy. The operating conditions for solid phase extraction (SPE) were optimized in column mode (pH, loading and elution flow rate using 1M thiourea in 1M HCl). The polymer was used for analyzing the toluene extracts of two reference materials (BCR-463 and TORT-2) with good accuracy. PMID:26452871

  1. Early Chronic Low-Level Methylmercury Poisoning in Monkeys Impairs Spatial Vision

    NASA Astrophysics Data System (ADS)

    Rice, Deborah C.; Gilbert, Steven G.

    1982-05-01

    Five monkeys were treated from birth with oral doses of mercury as methylmercury (50 micrograms per kilogram of body weight per day); concentrations in the blood peaked at 1.2 to 1.4 parts per million; and declined after weaning from infant formula to a steady level of 0.6 to 0.9 part per million. There were no overt signs of toxicity. When tested between 3 and 4 years of age under conditions of both high and low luminance, treated monkeys exhibited spatial vision that was impaired compared with that of control monkeys.

  2. EUROPattern Suite technology for computer-aided immunofluorescence microscopy in autoantibody diagnostics.

    PubMed

    Krause, C; Ens, K; Fechner, K; Voigt, J; Fraune, J; Rohwäder, E; Hahn, M; Danckwardt, M; Feirer, C; Barth, E; Martinetz, T; Stöcker, W

    2015-04-01

    Antinuclear autoantibodies (ANA) are highly informative biomarkers in autoimmune diagnostics. The increasing demand for effective test systems, however, has led to the development of a confusingly large variety of different platforms. One of them, the indirect immunofluorescence (IIF), is regarded as the common gold standard for ANA screening, as described in a position statement by the American College of Rheumatology in 2009. Technological solutions have been developed aimed at standardization and automation of IIF to overcome methodological limitations and subjective bias in IIF interpretation. In this review, we present the EUROPattern Suite, a system for computer-aided immunofluorescence microscopy (CAIFM) including automated acquisition of digital images and evaluation of IIF results. The system was originally designed for ANA diagnostics on human epithelial cells, but its applications have been extended with the latest system update version 1.5 to the analysis of antineutrophil cytoplasmic antibodies (ANCA) and anti-dsDNA antibodies. PMID:25801895

  3. Small Quantum Dots Conjugated to Nanobodies as Immunofluorescence Probes for Nanometric Microscopy

    PubMed Central

    2015-01-01

    Immunofluorescence, a powerful technique to detect specific targets using fluorescently labeled antibodies, has been widely used in both scientific research and clinical diagnostics. The probes should be made with small antibodies and high brightness. We conjugated GFP binding protein (GBP) nanobodies, small single-chain antibodies from llamas, with new ∼7 nm quantum dots. These provide simple and versatile immunofluorescence nanoprobes with nanometer accuracy and resolution. Using the new probes we tracked the walking of individual kinesin motors and measured their 8 nm step sizes; we tracked Piezo1 channels, which are eukaryotic mechanosensitive channels; we also tracked AMPA receptors on living neurons. Finally, we used a new super-resolution algorithm based on blinking of (small) quantum dots that allowed ∼2 nm precision. PMID:25397889

  4. Measuring NLR Oligomerization II: Detection of ASC Speck Formation by Confocal Microscopy and Immunofluorescence.

    PubMed

    Beilharz, Michael; De Nardo's, Dominic; Latz, Eicke; Franklin, Bernardo S

    2016-01-01

    Inflammasome assembly results in the formation of a large intracellular protein scaffold driven by the oligomerization of the adaptor protein apoptosis-associated speck-like protein containing a CARD (ASC). Following inflammasome activation, ASC polymerizes to form a large singular structure termed the ASC "speck," which is crucial for recruitment of caspase-1 and its inflammatory activity. Hence, due to the considerably large size of these structures, ASC specks can be easily visualized by microscopy as a simple upstream readout for inflammasome activation. Here, we provide two detailed protocols for imaging ASC specks: by (1) live-cell imaging of monocyte/macrophage cell lines expressing a fluorescently tagged version of ASC and (2) immunofluorescence of endogenous ASC in cell lines and human immune cells. In addition, we outline a protocol for increasing the specificity of ASC antibodies for use in immunofluorescence. PMID:27221487

  5. Localization of Ribulose Bisphosphate Carboxylase in the Guard Cells by an Indirect, Immunofluorescence Technique 1

    PubMed Central

    Madhavan, Soundararajan; Smith, Bruce N.

    1982-01-01

    Ribulose bisphosphate carboxylase, a key enzyme in the photosynthetic carboxylation process, has been localized through an indirect immunofluorescent technique in the guard cells of some of the 41 species of plants examined. This sample includes 17 families of both dicotyledons and monocotyledons, one gymnosperm, and one pteridophyte. Plants were selected to represent all of the three major photosynthetic categories, namely C3, C4, and Crassulacean acid metabolism. Antibodies raised against tobacco (Nicotiana tabacum L.) ribulose bisphosphate carboxylase were used for this immunofluorescent study. A good degree of fluorescence was observed in the guard cells of seven out of 21 species exhibiting Crassulacean acid metabolism. C3 plants exhibited a very low degree (almost negligible) of fluorescence, while the C4 species did not exhibit any fluorescence. Images PMID:16662174

  6. The serological diagnosis of Mycoplasma pneumoniae infection: a comparison of complement fixation, haemagglutination and immunofluorescence.

    PubMed Central

    Rousseau, S. A.; Tettmar, R. E.

    1985-01-01

    A total of 193 sera were examined for antibody to Mycoplasma pneumoniae by three techniques - complement fixation (CF), haemagglutination (HA) and immunofluorescence (IF), the last method being used to assess IgM, IgG and IgA antibodies. The most reliable single test for diagnosis was HA, and the most useful combination of tests was HA with IF (IgM and IgG). The IgA IF was not found to be diagnostically helpful. PMID:3934260

  7. Immunofluorescent Detection of Herpesvirus Antigens in Exfoliated Cells from Human Cervical Carcinoma

    PubMed Central

    Royston, Ivor; Aurelian, Laure

    1970-01-01

    Exfoliated cells from patients with squamous carcinoma of the cervix contain antigens related to herpesvirus subtype 2, as revealed by direct or indirect immunofluorescent techniques. Normal squamous cells from the same subjects and from controls without the disease, and cells from a small number of tumors at sites other than the cervix, did not react with anti-herpesvirus subtype 2 serum. Antisera to adenovirus 18 or mycoplasma orale did not react with the exfoliated cells. Images PMID:4318779

  8. Characterization of Antibodies to Products of Proinsulin Processing Using Immunofluorescence Staining of Pancreas in Multiple Species

    PubMed Central

    Asadi, Ali; Bruin, Jennifer E.

    2015-01-01

    The efficient processing of proinsulin into mature insulin and C-peptide is often compromised under conditions of beta cell stress, including diabetes. Impaired proinsulin processing has been challenging to examine by immunofluorescence staining in pancreas tissue because the characterization of antibodies specific for proinsulin, proinsulin intermediates, processed insulin and C-peptide has been limited. This study aimed to identify and characterize antibodies that can be used to detect products of proinsulin processing by immunofluorescence staining in pancreata from different species (mice, rats, dog, pig and human). We took advantage of several knockout mouse lines that lack either an enzyme involved in proinsulin processing or an insulin gene. Briefly, we report antibodies that are specific for several proinsulin processing products, including: a) insulin or proinsulin that has been appropriately processed at the B-C junction; b) proinsulin with a non-processed B-C junction; c) proinsulin with a non-processed A-C junction; d) rodent-specific C-peptide 1; e) rodent-specific C-peptide 2; and f) human-specific C-peptide or proinsulin. In addition, we also describe two ‘pan-insulin’ antibodies that react with all forms of insulin and proinsulin intermediates, regardless of the species. These antibodies are valuable tools for studying proinsulin processing by immunofluorescence staining and distinguishing between proinsulin products in different species. PMID:26216140

  9. Overview of developmental, reproductive, and behavioral/ neurological effects of mercury exposures in wildlife

    USGS Publications Warehouse

    Heinz, G.H.; Hoffman, D.; Klimstra, J.; Stebbins, K.

    2007-01-01

    studies with mallards (Anas platyrhynchos) suggest that the dietary concentrations of mercury that cause toxicity are lower than those set in fish consumption advisories to protect humans. Because wild mammals and birds are so sensitive to methylmercury poisoning and cannot escape dietary exposure the way humans can, guidelines set to protect wild birds and mammals may very well provide a margin of safety for human health.

  10. Methylmercury Alters the Activities of Hsp90 Client Proteins, Prostaglandin E Synthase/p23 (PGES/23) and nNOS

    PubMed Central

    Caito, Samuel; Zeng, Heng; Aschner, Judy L.; Aschner, Michael

    2014-01-01

    Methylmercury (MeHg) is a persistent pollutant with known neurotoxic effects. We have previously shown that astrocytes accumulate MeHg and play a prominent role in mediating MeHg toxicity in the central nervous system (CNS) by altering glutamate signaling, generating oxidative stress, depleting glutathione (GSH) and initiating lipid peroxidation. Interestingly, all of these pathways can be regulated by the constitutively expressed, 90-kDa heat shock protein, Hsp90. As Hsp90 function is regulated by oxidative stress, we hypothesized that MeHg disrupts Hsp90-client protein functions. Astrocytes were treated with MeHg and expression of Hsp90, as well as the abundance of complexes of Hsp90-neuronal nitric oxide synthase (nNOS) and Hsp90-prostaglandin E synthase/p23 (PGES/p23) were assessed. MeHg exposure decreased Hsp90 protein expression following 12 h of treatment while shorter exposures had no effect on Hsp90 protein expression. Interestingly, following 1 or 6 h of MeHg exposure, Hsp90 binding to PGES/p23 or nNOS was significantly increased, resulting in increased prostaglandin E2 (PGE2) synthesis from MeHg-treated astrocytes. These effects were attenuated by the Hsp90 antagonist, geldanmycin. NOS activity was increased following MeHg treatment while cGMP formation was decreased. This was accompanied by an increase in •O2− and H2O2 levels, suggesting that MeHg uncouples NO formation from NO-dependent signaling and increases oxidative stress. Altogether, our data demonstrates that Hsp90 interactions with client proteins are increased following MeHg exposure, but over time Hsp90 levels decline, contributing to oxidative stress and MeHg-dependent excitotoxicity. PMID:24852575

  11. Expression of human oxoguanine glycosylase 1 or formamidopyrimidine glycosylase in human embryonic kidney 293 cells exacerbates methylmercury toxicity in vitro

    SciTech Connect

    Ondovcik, Stephanie L.; Preston, Thomas J.; McCallum, Gordon P.; Wells, Peter G.

    2013-08-15

    Exposure to methylmercury (MeHg) acutely at high levels, or via chronic low-level dietary exposure from daily fish consumption, can lead to adverse neurological effects in both the adult and developing conceptus. To determine the impact of variable DNA repair capacity, and the role of reactive oxygen species (ROS) and oxidatively damaged DNA in the mechanism of toxicity, transgenic human embryonic kidney (HEK) 293 cells that stably express either human oxoguanine glycosylase 1 (hOgg1) or its bacterial homolog, formamidopyrimidine glycosylase (Fpg), which primarily repair the oxidative lesion 8-oxo-2′-deoxyguanosine (8-oxodG), were used to assess the in vitro effects of MeHg. Western blotting confirmed the expression of hOgg1 or Fpg in both the nuclear and mitochondrial compartments of their respective cell lines. Following acute (1–2 h) incubations with 0–10 μM MeHg, concentration-dependent decreases in clonogenic survival and cell growth accompanied concentration-dependent increases in lactate dehydrogenase (LDH) release, ROS formation, 8-oxodG levels and apurinic/apyrimidinic (AP) sites, consistent with the onset of cytotoxicity. Paradoxically, hOgg1- and Fpg-expressing HEK 293 cells were more sensitive than wild-type cells stably transfected with the empty vector control to MeHg across all cellular and biochemical parameters, exhibiting reduced clonogenic survival and cell growth, and increased LDH release and DNA damage. Accordingly, upregulation of specific components of the base excision repair (BER) pathway may prove deleterious potentially due to the absence of compensatory enhancement of downstream processes to repair toxic intermediary abasic sites. Thus, interindividual variability in DNA repair activity may constitute an important risk factor for environmentally-initiated, oxidatively damaged DNA and its pathological consequences. - Highlights: • hOgg1 and Fpg repair oxidatively damaged DNA. • hOgg1- and Fpg-expressing cells are more

  12. Genome-Wide Association Analysis of Tolerance to Methylmercury Toxicity in Drosophila Implicates Myogenic and Neuromuscular Developmental Pathways

    PubMed Central

    Montgomery, Sara L.; Vorojeikina, Daria; Huang, Wen; Mackay, Trudy F. C.; Anholt, Robert R. H.; Rand, Matthew D.

    2014-01-01

    Methylmercury (MeHg) is a persistent environmental toxin present in seafood that can compromise the developing nervous system in humans. The effects of MeHg toxicity varies among individuals, despite similar levels of exposure, indicating that genetic differences contribute to MeHg susceptibility. To examine how genetic variation impacts MeHg tolerance, we assessed developmental tolerance to MeHg using the sequenced, inbred lines of the Drosophila melanogaster Genetic Reference Panel (DGRP). We found significant genetic variation in the effects of MeHg on development, measured by eclosion rate, giving a broad sense heritability of 0.86. To investigate the influence of dietary factors, we measured MeHg toxicity with caffeine supplementation in the DGRP lines. We found that caffeine counteracts the deleterious effects of MeHg in the majority of lines, and there is significant genetic variance in the magnitude of this effect, with a broad sense heritability of 0.80. We performed genome-wide association (GWA) analysis for both traits, and identified candidate genes that fall into several gene ontology categories, with enrichment for genes involved in muscle and neuromuscular development. Overexpression of glutamate-cysteine ligase, a MeHg protective enzyme, in a muscle-specific manner leads to a robust rescue of eclosion of flies reared on MeHg food. Conversely, mutations in kirre, a pivotal myogenic gene identified in our GWA analyses, modulate tolerance to MeHg during development in accordance with kirre expression levels. Finally, we observe disruptions of indirect flight muscle morphogenesis in MeHg-exposed pupae. Since the pathways for muscle development are evolutionarily conserved, it is likely that the effects of MeHg observed in Drosophila can be generalized across phyla, implicating muscle as an additional hitherto unrecognized target for MeHg toxicity. Furthermore, our observations that caffeine can ameliorate the toxic effects of MeHg show that nutritional

  13. Mercury Exposure and Children’s Health

    PubMed Central

    Bose-O’Reilly, Stephan; McCarty, Kathleen M.; Steckling, Nadine; Lettmeier, Beate

    2011-01-01

    Acute or chronic mercury exposure can cause adverse effects during any period of development. Mercury is a highly toxic element; there is no known safe level of exposure. Ideally, neither children nor adults should have any mercury in their bodies because it provides no physiological benefit. Prenatal and postnatal mercury exposures occur frequently in many different ways. Pediatricians, nurses, and other health care providers should understand the scope of mercury exposures and health problems among children and be prepared to handle mercury exposures in medical practice. Prevention is the key to reducing mercury poisoning. Mercury exists in different chemical forms: elemental (or metallic), inorganic, and organic (methylmercury and ethyl mercury). Mercury exposure can cause acute and chronic intoxication at low levels of exposure. Mercury is neuro-, nephro-, and immunotoxic. The development of the child in utero and early in life is at particular risk. Mercury is ubiquitous and persistent. Mercury is a global pollutant, bio-accumulating, mainly through the aquatic food chain, resulting in a serious health hazard for children. This article provides an extensive review of mercury exposure and children’s health. PMID:20816346

  14. Vulnerability of dorsal root neurons and fibers toward methylmercury toxicity: a morphological evaluation

    SciTech Connect

    Yip, R.K.; Chang, L.W.

    1981-10-01

    The selective and relative sensitivity of various components (dorsal root neurons, dorsal root fibers, and ventral root fibers) of the dorsal root ganglia toward methylmercury toxicity were investigated. Charles River rats were orally administered methymercury chloride at a daily dose of 2.0 mg/kg body wt for 8 weeks. Dorsal root ganglia (L/sub 1/-S/sub 1/) were examined with light and electron microscopy. Extensive Wallerian-like degeneration was observed in the dorsal root fibers while no significant changes were found in the dorsal root neurons and in the ventral root fibers at the light-microscopic level. At the electron-microscopic level, only minor and possibly reversible changes, such as increase in lysosomes, neurofilamentous proliferation, and disintegration of the Nissl substance, were observed in the neuronal cell bodies while severe and irreversible degenerative changes occurred in the dorsal root fibers. No remarkable pathological changes were observed in the ventral root fibers. Schwann cells became hypertrophied and transformed into actively phagocytosing macrophages. It is concluded that while the dorsal root ganglia are highly vulnerable to the toxicity of methylmercury, the relative sensitivity to the toxic impact is: dorsal root fiber > dorsal root neuron (nerve cell body) > ventral root fibers.

  15. Mercury and methylmercury concentrations in Mediterranean seafood and surface sediments, intake evaluation and risk for consumers.

    PubMed

    Spada, Lucia; Annicchiarico, Cristina; Cardellicchio, Nicola; Giandomenico, Santina; Di Leo, Antonella

    2012-04-01

    Total mercury and methylmercury concentrations were measured in sediments and marine organisms from the Taranto Gulf to understand their distribution and partitioning. Sediment concentrations ranged from 0.036 to 7.730 mg/kg (mean: 2.777 mg/kg d.w.) and from 1 to 40 μg/kg (mean: 11 μg/kg d.w.) for total mercury (THg) and methylmercury (Me-Hg), respectively. In mollusks THg ranged from n.d. to 1870 μg/kg d.w. while in fish from 324 to 1740 μg/kg d.w. Me-Hg concentrations in fish ranged from 190 to 1040 μg/kg d.w. and from n.d. to 1321 μg/kg d.w. in mollusks. THg exceeded the maximum level fixed by the European Commission (0.5 mg/kg w.w.) only in gastropod Hexaplex t. The calculated weekly intake was in many cases over the Provisional Tolerable Weekly Intake established by EFSA for all edible species. These results seem to indicate that dietary consumption of this seafood implicates an appreciable risk for human health. PMID:21968333

  16. Methylmercury poisoning: long-term clinical, radiological, toxicological, and pathological studies of an affected family.

    PubMed

    Davis, L E; Kornfeld, M; Mooney, H S; Fiedler, K J; Haaland, K Y; Orrison, W W; Cernichiari, E; Clarkson, T W

    1994-06-01

    For 3 months in 1969 a family in the United States that included a pregnant mother consumed pork containing methylmercury. Children, aged 20, 13, and 8 years and a neonate, developed severe neurological signs. Twenty-two years later, the 2 oldest had cortical blindness or constricted visual fields, diminished hand proprioception, choreoathetosis, and attentional deficits. Magnetic resonance images showed tissue loss in the calcarine and parietal cortices and cerebellar folia. The youngest had quadriplegia, blindness, and severe mental retardation until their deaths. The brain of the 8-year-old who died at age 30 showed cortical atrophy, neuronal loss, and gliosis, most pronounced in the paracentral and parietooccipital regions. The total mercury level in formalin-fixed, left occipital cortex was 1,974 ng/gm as measured by atomic absorption. Regional brain mercury levels correlated with extent of brain damage. A control patient had 38.5 ng of mercury/gm in the occipital cortex. Systemic organs in the patient and a control subject had comparable mercury levels. In mercury-intoxicated rats, we found that only 5 to 10% of total brain mercury was lost by formalin fixation. Brain inorganic mercury in the patient ranged from 82 to 100%. Since inorganic mercury crosses the blood-brain barrier poorly, biotransformation of methyl to inorganic mercury may have occurred after methylmercury crossed the blood-brain barrier, accounting for its persistence in brain and causing part of the brain damage. PMID:8210224

  17. Enhanced reproduction in mallards fed a low level of methylmercury: An apparent case of hormesis

    USGS Publications Warehouse

    Heinz, G.H.; Hoffman, D.J.; Klimstra, J.D.; Stebbins, K.R.

    2010-01-01

    Breeding pairs of mallards (Anas platyrhynchos) were fed a control diet or a diet containing 0.5 mg/g mercury (Hg) in the form of methylmercury chloride. There were no effects of Hg on adult weights and no overt signs of Hg poisoning in adults. The Hg-containing diet had no effect on fertility of eggs, but hatching success of eggs was significantly higher for females fed 0.5 ??g/g Hg (71.8%) than for controls (57.5%). Survival of ducklings through 6 d of age was the same (97.8%) for controls and mallards fed 0.5 ??g/g mercury. However, the mean number of ducklings produced per female was significantly higher for the pairs fed 0.5 ??g/g Hg (21.4) than for controls (16.8). Although mercury in the parents' diet had no effect on mean duckling weights at hatching, ducklings from parents fed 0.5 mg/g Hg weighed significantly more (mean = 87.2 g) at 6 d of age than did control ducklings (81.0 g). The mean concentration of Hg in eggs laid by parents fed 0.5 ??g/g mercury was 0.81 ??g/g on a wet-weight basis. At this time, one cannot rule out the possibility that low concentrations of Hg in eggs may be beneficial, and this possibility should be considered when setting regulatory thresholds for methylmercury. ?? 2009 SETAC.

  18. [The effects of methylmercury on health in children and adults; national and international studies].

    PubMed

    González-Estecha, Montserrat; Bodas-Pinedo, Andrés; Rubio-Herrera, Miguel Ángel; Martell-Claros, Nieves; Trasobares-Iglesias, Elena M; Ordóñez-Iriarte, José M; Guillén-Pérez, José Jesús; Herráiz-Martínez, Miguel Ángel; García-Donaire, José Antonio; Farré-Rovira, Rosaura; Calvo-Manuel, Elpidio; Martínez-Álvarez, Jesús Román; Llorente-Ballesteros, M Teresa; Sáinz-Martín, María; Martínez-Astorquiza, Txantón; Martínez-García, M José; Bretón Lesmes, Irene; Cuadrado-Cenzual, M Ángeles; Prieto-Menchero, Santiago; Gallardo-Pino, Carmen; Moreno-Rojas, Rafael; Bermejo-Barrera, Pilar; Torres-Moreno, Miriam; Arroyo-Fernández, Manuel; Calle-Pascual, Alfonso

    2014-01-01

    The benefit of fish consumption in children and adults is well-known. However, it has been pointed out that excessive methylmercury intake due to consumption of contaminated fish leads to neurological toxicity in children, affecting cognitive function, memory, visual-motor function and language. After the intoxications in Minamata and Iraq, wide-ranging epidemiological studies were carried out in New Zealand, the Faroe Islands and the Seychelles and international recommendations were established for fish consumption in pregnant women and small children. In Spain, the Childhood and Environmental project (INMA, its Spanish acronym) has studied the effects of diet and the environment on fetal and childhood development in different geographic areas of Spain. National and international sudies have demonstrated that mercury concentrations are mainly dependent on fish consumption, although there are variations among countries which can be explained not only by the levels of fish consumption, but also by the type or species of fish that is consumed, as well as other factors. Although the best documented adverse effects of methylmercury are the effects on nervous sytem development in fetuses and newborns, an increasing number of studies indicate that cognitive function, reproduction and, especially, cardiovascular risk in the adult population can also be affected. However, more studies are necessary in order to confirm this and establish the existance of a causal relationship. PMID:25365002

  19. Methylmercury in water, sediment, and invertebrates in created wetlands of Rouge Park, Toronto, Canada.

    PubMed

    Sinclair, Kathleen A; Xie, Qun; Mitchell, Carl P J

    2012-12-01

    Thousands of hectares of wetlands are created annually because wetlands provide beneficial ecosystem services. Wetlands are also key sites for production of the bioaccumulative neurotoxin methylmercury (MeHg), but little is known about MeHg production in created systems. Here, we studied methylmercury in sediment, water, and invertebrates in created wetlands of various ages. Sediment MeHg reached 8 ng g(-1) in the newest wetland, which was significantly greater than in natural, control wetlands. This trend was mirrored in several invertebrate taxa, whose concentrations reached as high as 1.6 μg g(-1) in the newest wetland, above levels thought to affect reproduction in birds. The MeHg concentrations in created wetland invertebrate taxa generally decreased with increasing wetland age, possibly due to a combination of deeper anoxia and less organic matter accumulation in younger wetlands. A short-term management intervention and/or improved engineering design may be necessary to reduce the mercury-associated risk in newly created wetlands. PMID:22940274

  20. IMEP-115: determination of methylmercury in seafood by elemental mercury analysis: collaborative study.

    PubMed

    Cordeiro, Fernando; Calderón, Josep; Gonçalves, Susana; Lourenço, Maria Helena; Robouch, Piotr; Emteborg, Hakan; Conneely, Patrick; Tumba-Tshilumba, Marie-France; de la Calle, Maria Beatriz

    2014-01-01

    A collaborative study IMEP-115 was organized by the European Union Reference Laboratory for Heavy Metals in Feed and Food (EURL-HM) to validate a method for the determination of methylmercury in seafood. The method was based on a liquid-liquid extraction with an organic solvent and with an aqueous cysteine solution. The final quantitation was done with an elemental mercury analyzer. Fifteen laboratories experienced in elemental mercury analyses, from 10 European countries, took part in the exercise. Five test items were selected to cover the concentration range from 0.013 to 5.12 mg/kg. All test items were reference materials certified for the methylmercury mass fraction: DOLT-4 (dogfish liver), TORT-2 (lobster hepatopancreas), SRM 2974a (mussel), SRM 1566b (oyster), and ERM CE-464 (tuna). Participants also received a bottle of ERM CE-463 (tuna) to test their analytical method before starting the collaborative study. Method validation showed adequate accuracy and acceptable precision for all test items, thus fitting its intended analytical purpose. The repeatability RSD ranged from 3.9 to 12.3%, while the reproducibility RSD ranged from 8.4 to 24.8%. PMID:24830172

  1. Mercury and methylmercury stream concentrations in a Coastal Plain watershed: A multi-scale simulation analysis

    USGS Publications Warehouse

    Knightes, Christopher D.; Golden, Heather E.; Journey, Celeste A.; Davis, Gary M.; Conrads, Paul A.; Marvin-DiPasquale, Mark; Brigham, Mark E.; Bradley, Paul M.

    2014-01-01

    Mercury is a ubiquitous global environmental toxicant responsible for most US fish advisories. Processes governing mercury concentrations in rivers and streams are not well understood, particularly at multiple spatial scales. We investigate how insights gained from reach-scale mercury data and model simulations can be applied at broader watershed scales using a spatially and temporally explicit watershed hydrology and biogeochemical cycling model, VELMA. We simulate fate and transport using reach-scale (0.1 km2) study data and evaluate applications to multiple watershed scales. Reach-scale VELMA parameterization was applied to two nested sub-watersheds (28 km2 and 25 km2) and the encompassing watershed (79 km2). Results demonstrate that simulated flow and total mercury concentrations compare reasonably to observations at different scales, but simulated methylmercury concentrations are out-of-phase with observations. These findings suggest that intricacies of methylmercury biogeochemical cycling and transport are under-represented in VELMA and underscore the complexity of simulating mercury fate and transport.

  2. Effects of Methylmercury on Reproduction in American Kestrels and Comparison to Effects Observed in Other Avian Species, poster presentation

    EPA Science Inventory

    To assess the effects of methylmercury (MeHg) on the survival and reproduction of birds, several controlled-dose laboratory studies have been conducted over the years on a variety of avian species, but none of the previous studies measured reproductive effects in a flesh-eating s...

  3. Influence of Reservoir Water Level Fluctuations on Sediment Methylmercury Concentrations Downstream of the Historical Black Butte Mercury Mine, OR

    EPA Science Inventory

    Mercury (Hg) is a pollutant of global concern due to its ability to accumulate as methylmercury (MeHg) in biota. Mercury is methylated by anaerobic microorganisms such as sulfate reducing bacteria (SRB) in water and sediment. Throughout North America, reservoirs tend to have e...

  4. RETROSPECTIVE STUDY OF METHYLMERCURY AND OTHER METAL(LOID)S IN MADAGASCAR UNPOLISHED RICE (Oryza sativa L.)

    PubMed Central

    Rothenberg, Sarah E.; Mgutshini, Noma L.; Bizimis, Michael; Johnson-Beebout, Sarah E.; Ramanantsoanirina, Alain

    2014-01-01

    The rice ingestion rate in Madagascar is among the highest globally; however studies concerning metal(loid) concentrations in Madagascar rice are lacking. For Madagascar unpolished rice (n=51 landraces), levels of toxic elements (e.g., total mercury, methylmercury, arsenic and cadmium) as well as essential micronutrients (e.g., zinc and selenium) were uniformly low, indicating potentially both positive and negative health effects. Aside from manganese (Wilcoxon rank sum, p<0.01), no significant differences in concentrations for all trace elements were observed between rice with red bran (n=20) and brown bran (n=31) (Wilcoxon rank sum, p=0.06–0.91). Compared to all elements in rice, rubidium (i.e., tracer for phloem transport) was most positively correlated with methylmercury (Pearson's r=0.33, p<0.05) and total mercury (r=0.44, p<0.05), while strontium (i.e., tracer for xylem transport) was least correlated with total mercury and methylmercury (r<0.01 for both), suggesting inorganic mercury and methylmercury were possibly more mobile in phloem compared to xylem. PMID:25463705

  5. EFFECTS OF A PERMEABLE REACTIVE BARRIER ON DENITRIFYING BACTERIA COMMUNITIES AND METHYLMERCURY CONCENTRATIONS IN WAQUOIT BAY, MA

    EPA Science Inventory

    It is expected that microbial denitrifying bacterial communities in the barrier will be distinct from those at control sites due to the high amount of degradable carbon and the unique redox conditions present within the barrier. It also is expected that toxic methylmercury ...

  6. Determination of methylmercury by electrothermal atomic absorption spectrometry using headspace single-drop microextraction with in situ hydride generation

    NASA Astrophysics Data System (ADS)

    Gil, Sandra; Fragueiro, Sandra; Lavilla, Isela; Bendicho, Carlos

    2005-01-01

    A new method is proposed for preconcentration and matrix separation of methylmercury prior to its determination by electrothermal atomic absorption spectrometry (ETAAS). Generation of methylmercury hydride (MeHgH) from a 5-ml solution is carried out in a closed vial and trapped onto an aqueous single drop (3-μl volume) containing Pd(II) or Pt(IV) (50 and 10 mg/l, respectively). The hydrogen evolved in the headspace (HS) after decomposition of sodium tetrahydroborate (III) injected for hydride generation caused the formation of finely dispersed Pd(0) or Pt(0) in the drop, which in turn, were responsible for the sequestration of MeHgH. A preconcentration factor of ca. 40 is achieved with both noble metals used as trapping agents. The limit of detection of methylmercury was 5 and 4 ng/ml (as Hg) with Pd(II) or Pt(IV) as trapping agents, and the precision expressed as relative standard deviation was about 7%. The preconcentration system was fully characterised through optimisation of the following variables: Pd(II) or Pt(IV) concentration in the drop, extraction time, pH of the medium, temperatures of both sample solution and drop, concentration of salt in the sample solution, sodium tetrahydroborate (III) concentration in the drop and stirring rate. The method has been successfully validated against two fish certified reference materials (CRM 464 tuna fish and CRM DORM-2 dogfish muscle) following selective extraction of methylmercury in 2 mol/l HCl medium.

  7. Immunohistochemical identification of Renibacterium salmoninarum by monoclonal antibodies in paraffin-embedded tissues of Atlantic salmon (Salmo salar L.), using paired immunoenzyme and paired immunofluorescence techniques.

    PubMed

    Evensen, O; Dale, O B; Nilsen, A

    1994-01-01

    Renibacterium salmoninarum was identified in situ by immunoenzymatic and immunofluorescence techniques in paraffin-embedded tissue specimens collected during a natural outbreak of bacterial kidney disease (BKD) and from an experimental infection in Atlantic salmon (Salmo salar L.). Monoclonal antibodies (MAbs) 4D3 and 2G5 were used in this study, both specific for the 57-58-kD outer membrane protein (p57) of the bacterium. Both MAbs revealed positive staining in ethanol-fixed tissue specimens, but only the epitope identified by MAb 4D3 was formalin resistant. Pretreatment with trypsin did not reestablish the antigenicity for the epitope identified by Mab 2G5. Paired immunoenzymatic staining for identification of the bacterium in sequential incubation steps on ethanol-fixed tissue specimens using an avidin-biotin-peroxidase system was obtained after serial dilution of the Mab (2G5) or the chromagen, amino ethyl carbazole, in the first sequence. Paired immunofluorescence staining with well-balanced color mixing was easily obtained on ethanol-fixed tissue specimens using sequential incubations. Single exposures gave blue (aminomethyl coumarin acetic acid) and green (fluorescein isothiocyanate) fluorescence for MAbs 2G5 and biotinylated 4D3, respectively. Color mixing was revealed as a turquoise staining. Studies on method sensitivity was performed by incorporating a known amount of a protein preparation of p57 into an inert matrix, creating an artificial test substrate.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:8011782

  8. Direct immunofluorescence of the outer root sheath in anagen and telogen hair in pemphigus vulgaris and pemphigus foliaceus.

    PubMed

    Tanasilovic, Srdjan; Medenica, Ljiljana; Popadic, Svetlana

    2014-11-01

    Direct immunofluorescence of peri-lesional skin is the gold standard in the diagnosis of pemphigus. A specific immunofluorescence pattern may also be demonstrated in the outer root sheath of anagen and telogen hair. We demonstrated an intercellular reticular deposition of immunoglobulin G in the outer root sheath of plucked anagen and telogen hair in all pemphigus vulgaris patients with active disease and for the first time in all patients with active pemphigus foliaceus. Moreover, we demonstrated for the first time that plucked hair samples may be kept at -20°C for at least 2 weeks before immunofluorescent staining and analysis. PMID:23713982

  9. Varying coefficient function models to explore interactions between maternal nutritional status and prenatal methylmercury toxicity in the Seychelles Child Development Nutrition Study

    SciTech Connect

    Lynch, Miranda L.; Huang, Li-Shan; Cox, Christopher; Strain, J.J.; Myers, Gary J.; Bonham, Maxine P.; Shamlaye, Conrad F.; Stokes-Riner, Abbie; Wallace, Julie M.W.; Duffy, Emeir M.; Clarkson, Thomas W.; Davidson, Philip W.

    2011-01-15

    Maternal consumption of fish during the gestational period exposes the fetus to both nutrients, especially the long-chain polyunsaturated fatty acids (LCPUFAs), believed to be beneficial for fetal brain development, as well as to the neurotoxicant methylmercury (MeHg). We recently reported that nutrients present in fish may modify MeHg neurotoxicity. Understanding the apparent interaction of MeHg exposure and nutrients present in fish is complicated by the limitations of modeling methods. In this study we fit varying coefficient function models to data from the Seychelles Child Development Nutrition Study (SCDNS) cohort to assess the association of dietary nutrients and children's development. This cohort of mother-child pairs in the Republic of Seychelles had fish consumption averaging 9 meals per week. Maternal nutritional status was assessed for five different nutritional components known to be present in fish (n-3 LCPUFA, n-6 LCPUFA, iron status, iodine status, and choline) and associated with children's neurological development. We also included prenatal MeHg exposure (measured in maternal hair). We examined two child neurodevelopmental outcomes (Bayley Scales Infant Development-II (BSID-II) Mental Developmental Index (MDI) and Psychomotor Developmental Index (PDI)), each administered at 9 and at 30 months. The varying coefficient models allow the possible interactions between each nutritional component and MeHg to be modeled as a smoothly varying function of MeHg as an effect modifier. Iron, iodine, choline, and n-6 LCPUFA had little or no observable modulation at different MeHg exposures. In contrast the n-3 LCPUFA docosahexaenoic acid (DHA) had beneficial effects on the BSID-II PDI that were reduced or absent at higher MeHg exposures. This study presents a useful modeling method that can be brought to bear on questions involving interactions between covariates, and illustrates the continuing importance of viewing fish consumption during pregnancy as a case

  10. Intraperitoneal injections as a possible means of generating varied levels of methylmercury in the eggs of birds in field studies

    USGS Publications Warehouse

    Heinz, Gary H.; Hoffman, David J.; Klimstra, Jon D.; Stebbins, Katherine R.

    2010-01-01

    The ideal study of the effects of methylmercury on the reproductive success of a species of bird would be one in which eggs contained mercury concentrations ranging from controls to very heavily contaminated, all at the same site. Such a study cannot be realized at a mercury contaminated area or under laboratory conditions, but could be achieved by introducing methylmercury into breeding females and allowing them to deposit mercury in their eggs. Female mallards (Anas platyrhynchos) were intraperitoneally injected with solutions of methylmercury chloride dissolved in corn oil, propylene glycol, dimethyl sulfoxide, mineral oil, Olestra, Crisco, lard, hard paraffin, and a combination of hard and soft paraffin. In some cases, egg laying was delayed, either due to the solvent itself (in the case of Olestra, Crisco, and lard) or to the highest concentration of methylmercury chloride (500 μg/g) in some of the solvents. Mercury in eggs ranged from a control level (< 0.1 μg/g) to approximately 14 μg/g on a wet weight basis, which more than covers the range of concentrations reported in wild bird eggs. Mercury concentrations in a series of eggs from the same female declined mostly due to excretion of mercury in prior eggs and not because of the length of time since the injection. Intraperitoneal injections hold promise in field studies where one would like to study the reproductive effects of a wide range of methylmercury levels in the eggs of a wild bird and under the natural conditions that exist in the field.

  11. Human exposure to mercury: A critical assessment of the evidence of adverse health effects

    SciTech Connect

    Ratcliffe, H.E.; Swanson, G.M.; Fischer, L.J.

    1996-10-25

    The ubiquitous nature of mercury in the environment, its global atmospheric cycling, and its toxicity to humans at levels that are uncomfortably close to exposures experienced by a proportion of the population are some of the current concerns associated with this pollutant. The purpose of this review is to critically evaluate the scientific quality of published reports involving human exposures to mercury and associated health outcomes as an aid in the risk evaluation of this chemical. A comprehensive review of the scientific literature involving human exposures to mercury was performed and each publication evaluated using a defined set of criteria that are considered standards in epidemiologic and toxicologic research. Severe, sometimes fatal, effects of mercury exposure at high levels were primarily reported as case studies. The disasters in Minamata, Japan, in the 1950s and in Iraq in 1971-1972 clearly demonstrated neurologic effects associated with ingestion of methylmercury both in adults and in infants exposed in utero. The effects were convincingly Associated with methylmercury ingestion, despite limitations of the study design. Several well-conducted studies have investigated the effects of methylmercury at levels below those in the Iraq incident but have not provided clear evidence of an effect. The lower end of the dose-response curve constructed from the Iraq data therefore still needs to be confirmed. The studies of mercury exposure in the workplace were mainly of elemental or inorganic mercury, and effects that were observed at relatively low exposure levels were primarily neurologic and renal. Several studies have investigated effects associated with dental amalgam but have been rated as inconclusive because of methodologic deficiencies. In our overall evaluation, 29 of 110 occupational studies and 20 of 54 studies where exposure occurred in the natural environment provided at least suggestive evidence of an exposure-related effect. 259 refs., 4 tabs.

  12. Comparison of rapid immunofluorescence procedure with TestPack RSV and Directigen FLU-A for diagnosis of respiratory syncytial virus and influenza A virus.

    PubMed Central

    Todd, S J; Minnich, L; Waner, J L

    1995-01-01

    A rapid immunofluorescence format requiring 20 min for completion was as effective as conventional indirect and direct immunofluorescence procedures for detecting respiratory syncytial virus and influenza A virus antigens in clinical specimens. Rapid immunofluorescence was more sensitive than TestPack RSV and comparable to Directigen FLU-A immunosorbent assays, which require 20 min for completion. PMID:7650206

  13. An automated approach to the segmentation of HEp-2 cells for the indirect immunofluorescence ANA test.

    PubMed

    Tonti, Simone; Di Cataldo, Santa; Bottino, Andrea; Ficarra, Elisa

    2015-03-01

    The automatization of the analysis of Indirect Immunofluorescence (IIF) images is of paramount importance for the diagnosis of autoimmune diseases. This paper proposes a solution to one of the most challenging steps of this process, the segmentation of HEp-2 cells, through an adaptive marker-controlled watershed approach. Our algorithm automatically conforms the marker selection pipeline to the peculiar characteristics of the input image, hence it is able to cope with different fluorescent intensities and staining patterns without any a priori knowledge. Furthermore, it shows a reduced sensitivity to over-segmentation errors and uneven illumination, that are typical issues of IIF imaging. PMID:25614095

  14. Direct immunofluorescence testing in the diagnosis of immunobullous disease, collagen vascular disease, and vascular injury syndromes.

    PubMed

    Magro, Cynthia M; Roberts-Barnes, Jennifer; Crowson, A Neil

    2012-10-01

    Direct and indirect immunofluorescence (IF) plays a role in the evaluation of immunobullous diseases and their mimics, and in the investigation of vascular injury syndromes and autoimmune connective tissue disease (CTD). IF mapping may be an important adjunct in the assessment of congenital epidermolysis bullosa syndromes and in Alport disease, in which antibodies are directed at certain components of the basement membrane zone to assay for their deficiency. In many cases of immunobullous and autoimmune CTDs, correlation with direct IF results is useful and often decisive in lesional evaluation and thus in patient management. PMID:23021058

  15. [Immunofluorescent diagnosis of Entamoeba histolytica trophocoites in preserved stool specimens of patients (author's transl)].

    PubMed

    Hess, U; Fröhlich, A

    1979-09-01

    A fixative and examination technique is described for identification of Entamoeba histolytica trophocoites in faeces with the aid of the indirect immunofluorescence technique. Magnaforms in bloody-dysenteric specimens and Minutaforms in spontaneous or saline purged specimens give equally good fluorescence. The specifity of the rabbit antiserum against axenically grown E. hist. is good: There is strong positive reaction only with trophocoites of E. hist. Weak crossreactions are encountered with trophocoites of E. coli, E. hartmanni and E. polecki. Negative reactions are encountered with trophocoites of Endolimax nana, Jodamoeba bāutschlii, and Dientamoeba fragilis. Amebic cysts, flagellates, leucocytes, epithelial cells and Blastocytis give negative reactions, too. PMID:94475

  16. [Determination of anti-rabies antibodies by means of the indirect immunofluorescence method].

    PubMed

    Jiran, E; Závora, M

    1975-06-01

    The paper presents a description of the method of indirect immunofluorescence (IFRA test) for the demonstration of post-vaccination anti-rabies antibodies. The model of immune hamster serum was used to study the reproducibility of the test. The dynamics of antibody formation was quantitatively examined in rabbits immunized by the Flury-LEP virus. For brief information, the test was also used for the demonstration of post-vaccination antibodes against rabies in dogs. The method can be recommended as an additional and orientation test for the evaluation of the immunogenic properties of vaccines against rabies. PMID:810938

  17. ISOLATION AND DETECTION OF GIARDIA CYSTS FROM WATER USING DIRECT IMMUNOFLUORESCENCE.

    USGS Publications Warehouse

    Sorenson, Stephen K.; Riggs, John L.; Dileanis, Peter D.; Suk, Thomas J.

    1986-01-01

    A water-sampling apparatus used for the isolation and detection of Giardia cysts in water has been designed and tested. The sampling apparatus uses one of a variety of pumps or waterline pressure to move water through a filter. Two of the optional pumps are lightweight enough to make the apparatus portable and thus suitable for sampling in remote areas. This technique of sample processing produces good cyst recovery in much less time than is required with previously established methods. Giardia cysts are identified using direct immunofluorescence.

  18. Methylmercury, an environmental electrophile capable of activation and disruption of the Akt/CREB/Bcl-2 signal transduction pathway in SH-SY5Y cells

    PubMed Central

    Unoki, Takamitsu; Abiko, Yumi; Toyama, Takashi; Uehara, Takashi; Tsuboi, Koji; Nishida, Motohiro; Kaji, Toshiyuki; Kumagai, Yoshito

    2016-01-01

    Methylmercury (MeHg) modifies cellular proteins via their thiol groups in a process referred to as “S-mercuration”, potentially resulting in modulation of the cellular signal transduction pathway. We examined whether low-dose MeHg could affect Akt signaling involved in cell survival. Exposure of human neuroblastoma SH-SY5Y cells of up to 2 μM MeHg phosphorylated Akt and its downstream signal molecule CREB, presumably due to inactivation of PTEN through S-mercuration. As a result, the anti-apoptotic protein Bcl-2 was up-regulated by MeHg. The activation of Akt/CREB/Bcl-2 signaling mediated by MeHg was, at least in part, linked to cellular defence because either pretreatment with wortmannin to block PI3K/Akt signaling or knockdown of Bcl-2 enhanced MeHg-mediated cytotoxicity. In contrast, increasing concentrations of MeHg disrupted Akt/CREB/Bcl-2 signaling. This phenomenon was attributed to S-mercuration of CREB through Cys286 rather than Akt. These results suggest that although MeHg is an apoptosis-inducing toxicant, this environmental electrophile is able to activate the cell survival signal transduction pathway at lower concentrations prior to apoptotic cell death. PMID:27357941

  19. Phytoremediation Potential of Maná-Cubiu (Solanum sessiliflorum Dunal) for the Deleterious Effects of Methylmercury on the Reproductive System of Rats

    PubMed Central

    Frenedoso da Silva, Raquel; Missassi, Gabriela; dos Santos Borges, Cibele; Silva de Paula, Eloísa; Hornos Carneiro, Maria Fernanda; Barbosa Junior, Fernando; De Grava Kempinas, Wilma

    2014-01-01

    Methylmercury, organic form of mercury, can increase the number of abnormal sperm and decrease sperm concentration and testosterone levels possibly due to the damage caused by reactive species to germ and Leydig cells. Maná-cubiu (Solanum sessiliflorum Dunal) is a native fruit from Amazon rich in iron, zinc, niacin, pectin, and citric acid, used in foods, beverages, and medicinal purposes, since it has been useful for treatment of various diseases caused by oxidative stress or nutritional deficiency. Therefore, this study evaluated the phytoremediation potential of this fruit on damages caused by exposure to MeHg on sperm quantity and quality and the histological aspect of the testis and epididymis. Wistar male rats (n = 20) were randomly allocated into four groups: Control group (received distilled water), MeHg group (140 μg/Kg), Solanum group (1% of fruit Maná-cubiu on chow), and Solanum plus MeHg group (same treatment as MeHg and Solanum group). The organs were weighted, histopathology; sperm morphology and counts were obtained. The results showed reduction in body weight gain, testis weights, reduced sperm production, and increased histopathological abnormalities in the MeHg-treated group. However, treatment with Solanum plus MeHg revealed a protective effect of this fruit on damages caused by MeHg. PMID:24772420

  20. Antioxidant and neuroprotective activity of the extract from the seaweed, Halimeda incrassata (Ellis) Lamouroux, against in vitro and in vivo toxicity induced by methyl-mercury.

    PubMed

    Linares, Adyary Fallarero; Loikkanen, Jarkko; Jorge, Mancini-Filho; Soria, René Barro; Novoa, Alexis Vidal

    2004-02-01

    A growing body of evidence suggests oxidative stress as part of the toxicity mechanism of methyl-mercury (MeHg) in cell cultures and animal models and so justifies the use of natural antioxidants as therapeutic alternatives. This research examines the effect of an aqueous extract from the marine seaweed Halimeda incrassata (Hi) against the oxidative stress induced by MeHg on in vitro and in vivo models. In GT1-7 mouse hypothalamic cell cultures, the extract of Hi increased cell viability and reduced ROS production after 24-h exposure to MeHgCl. Wistar rats, acutely intoxicated with MeHgCl, had reduced levels of serum and brain thiobarbituric reactive substances when treated with the Hi extract. Similarly, animals exposed to repeated doses of MeHgCl were protected by the seaweed extract from variations in body weight, food consumption and the appearance of neurological effects. This research supports the notion that oxidative stress is directly involved in MeHg intoxication, so that natural antioxidants, particularly those in the extract of Hi, can be useful therapeutic alternatives. PMID:14748406

  1. Immunotoxic Effect of Low-Dose Methylmercury Is Negligible in Mouse Models of Ovalbumin or Mite-Induced Th2 Allergy.

    PubMed

    Nakamura, Ryosuke; Takanezawa, Yasukazu; Sone, Yuka; Uraguchi, Shimpei; Sakabe, Kou; Kiyono, Masako

    2016-01-01

    Methylmercury (MeHg) is one of the most toxic environmental pollutants and presents a serious hazard to health worldwide. Although the adverse effects of MeHg, including neurotoxicity, have been studied, its effects on immune function, in particular the immune response, remain unclear. This study examined the effects of low-dose MeHg on immune responses in mice. Mice were orally immunized with ovalbumin (OVA) or subcutaneously injected with mite extract to induce a T-helper 2 (Th2) allergic response. They were then exposed to MeHg (0, 0.02, 1.0, or 5.0 mg·kg(-1)·d(-1)). Immunization with oral OVA or subcutaneous mite extract increased serum levels of OVA-specific immunoglobulin (Ig) E (OVA-IgE), OVA-IgG1, interleukin (IL)-4, and IL-13, and total IgE, total IgG, and IL-13 when compared with levels in non-immunized mice. However, no interferon (IFN)-γ was detected. By contrast, serum levels of OVA-IgE, OVA-IgG1, IL-4, and IL-13, or total IgE, total IgG, and IL-13 in Th2 allergy model mice subsequently treated with MeHg were no higher than those in MeHg-untreated mice. These results suggest that MeHg exposure has no adverse effects on Th2 immune responses in antigen-immunized mice. PMID:27476942

  2. A new approach to understand methylmercury (CH3Hg) sources and transformation pathways: Compound-specific carbon stable isotope analysis by GC-C-IRMS

    NASA Astrophysics Data System (ADS)

    Baya, P. A.; Point, D.; Amouroux, D. P.; Lebreton, B.; Guillou, G.

    2015-12-01

    Methylmercury (CH3Hg) is a potent neurotoxin which is readily assimilated by organisms and bio-accumulates in aquatic food webs. In humans, consumption of CH3Hg contaminated marine fish is the major route of mercury exposure. However, our understanding of CH3Hg transformation pathways is still incomplete. To close this knowledge gap, we propose to explore the stable carbon isotopic composition (δ13C) of the methyl group of CH3Hg for a better understanding of its sources and transformation mechanisms. The method developed for the determination of the δ13C value of CH3Hg in biological samples involves (i) CH3Hg selective extraction, (ii) derivatization, and (iii) separation by gas chromatography (GC) prior to analysis by combustion isotope ratio mass spectrometry (C-IRMS). We present the figures of merit of this novel method and the first δ13C signatures for certified materials (ERM-CE464, BCR414) and biological samples at different marine trophic levels (i.e., tuna fish, zooplankton). The implications of this new approach to trace the pathways associated with Hg methylation and the mechanisms involved will be discussed.

  3. Methylmercury, an environmental electrophile capable of activation and disruption of the Akt/CREB/Bcl-2 signal transduction pathway in SH-SY5Y cells.

    PubMed

    Unoki, Takamitsu; Abiko, Yumi; Toyama, Takashi; Uehara, Takashi; Tsuboi, Koji; Nishida, Motohiro; Kaji, Toshiyuki; Kumagai, Yoshito

    2016-01-01

    Methylmercury (MeHg) modifies cellular proteins via their thiol groups in a process referred to as "S-mercuration", potentially resulting in modulation of the cellular signal transduction pathway. We examined whether low-dose MeHg could affect Akt signaling involved in cell survival. Exposure of human neuroblastoma SH-SY5Y cells of up to 2 μM MeHg phosphorylated Akt and its downstream signal molecule CREB, presumably due to inactivation of PTEN through S-mercuration. As a result, the anti-apoptotic protein Bcl-2 was up-regulated by MeHg. The activation of Akt/CREB/Bcl-2 signaling mediated by MeHg was, at least in part, linked to cellular defence because either pretreatment with wortmannin to block PI3K/Akt signaling or knockdown of Bcl-2 enhanced MeHg-mediated cytotoxicity. In contrast, increasing concentrations of MeHg disrupted Akt/CREB/Bcl-2 signaling. This phenomenon was attributed to S-mercuration of CREB through Cys286 rather than Akt. These results suggest that although MeHg is an apoptosis-inducing toxicant, this environmental electrophile is able to activate the cell survival signal transduction pathway at lower concentrations prior to apoptotic cell death. PMID:27357941

  4. Phytoremediation potential of Maná-Cubiu (Solanum sessiliflorum Dunal) for the deleterious effects of methylmercury on the reproductive system of rats.

    PubMed

    Frenedoso da Silva, Raquel; Missassi, Gabriela; dos Santos Borges, Cibele; Silva de Paula, Eloísa; Hornos Carneiro, Maria Fernanda; Grotto, Denise; Barbosa Junior, Fernando; De Grava Kempinas, Wilma

    2014-01-01

    Methylmercury, organic form of mercury, can increase the number of abnormal sperm and decrease sperm concentration and testosterone levels possibly due to the damage caused by reactive species to germ and Leydig cells. Maná-cubiu (Solanum sessiliflorum Dunal) is a native fruit from Amazon rich in iron, zinc, niacin, pectin, and citric acid, used in foods, beverages, and medicinal purposes, since it has been useful for treatment of various diseases caused by oxidative stress or nutritional deficiency. Therefore, this study evaluated the phytoremediation potential of this fruit on damages caused by exposure to MeHg on sperm quantity and quality and the histological aspect of the testis and epididymis. Wistar male rats (n = 20) were randomly allocated into four groups: Control group (received distilled water), MeHg group (140 μg/Kg), Solanum group (1% of fruit Maná-cubiu on chow), and Solanum plus MeHg group (same treatment as MeHg and Solanum group). The organs were weighted, histopathology; sperm morphology and counts were obtained. The results showed reduction in body weight gain, testis weights, reduced sperm production, and increased histopathological abnormalities in the MeHg-treated group. However, treatment with Solanum plus MeHg revealed a protective effect of this fruit on damages caused by MeHg. PMID:24772420

  5. Diphenyl diselenide, a simple organoselenium compound, decreases methylmercury-induced cerebral, hepatic and renal oxidative stress and mercury deposition in adult mice.

    PubMed

    de Freitas, Andressa Sausen; Funck, Vinícius Rafael; Rotta, Mariana dos Santos; Bohrer, Denise; Mörschbächer, Vanessa; Puntel, Robson Luís; Nogueira, Cristina Wayne; Farina, Marcelo; Aschner, Michael; Rocha, João Batista Teixeira

    2009-04-01

    Oxidative stress has been pointed out as an important molecular mechanism in methylmercury (MeHg) intoxication. At low doses, diphenyl diselenide ((PhSe)2), a structurally simple organoselenium compound, has been shown to possess antioxidant and neuroprotective properties. Here we have examined the possible in vivo protective effect of diphenyl diselenide against the potential pro-oxidative effects of MeHg in mouse liver, kidney, cerebrum and cerebellum. The effects of MeHg exposure (2 mg/(kg day) of methylmercury chloride 10 ml/kg, p.o.), as well as the possible antagonist effect of diphenyl diselenide (1 and 0.4 mg/(kg day); s.c.) on body weight gain and on hepatic, cerebellar, cerebral and renal levels of thiobarbituric acid reactive substances (TBARS), non-protein thiols (NPSH), ascorbic acid content, mercury concentrations and activities of antioxidant enzymes (glutathione peroxidase (GPx), catalase (CAT) and superoxide dismutase (SOD)) were evaluated after 35 days of treatment. MeHg caused an increase in TBARS and decreased NPSH levels in all tissues. MeHg also induced a decrease in hepatic ascorbic acid content and in renal GPx and CAT activities. Diphenyl diselenide (1 mg/kg) conferred protection against MeHg-induced hepatic and renal lipid peroxidation and at both doses prevented the reduction in hepatic NPSH levels. Diphenyl diselenide also conferred a partial protection against MeHg-induced oxidative stress (TBARS and NPSH) in liver and cerebellum. Of particular importance, diphenyl diselenide decreased the deposition of Hg in cerebrum, cerebellum, kidney and liver. The present results indicate that diphenyl diselenide can protect against some toxic effects of MeHg in mice. This protection may be related to its antioxidant properties and its ability to reduce Hg body burden. We posit that formation of a selenol intermediate, which possesses high nucleophilicity and high affinity for MeHg, accounts for the ability of diphenyl diselenide to ameliorate Me

  6. Antagonistic interaction of selenomethionine enantiomers on methylmercury toxicity in the microalgae Chlorella sorokiniana.

    PubMed

    Moreno, Fernando; García-Barrera, Tamara; Gómez-Jacinto, Verónica; Gómez-Ariza, José Luis; Garbayo-Nores, Inés; Vílchez-Lobato, Carlos

    2014-02-01

    The protective effect of selenium against mercury toxicity is well known especially between selenomethionine and methylmercury and it has been studied in several living organisms, however information is lacking about the interaction of these species in Chlorella. Investigation into which chiral form of selenomethionine effectively acts against the toxic effects of methylmercury has not previously been carried out. In the present work, two control cultures and two cultures of C. sorokiniana were grown in standard medium with D,L-SeMet, L-SeMet or D-SeMet. After the experiment was started up MeHg(+) was added periodically to the cultures containing D,L-SeMet, L-SeMet, D-SeMet and to one of the control batches. The results show that both SeMet enantiomers counteract the toxicity of MeHg(+), by markedly increasing the total content of chlorophyll, carotenoids, as well as the dry weight and light dependent oxygen production, compared to the culture which is non pre-treated with SeMet and is only exposed to MeHg(+). The levels of MeHg(+) measured in cells are lower in the cultures pre-treated with SeMet indicating that the passage of MeHg(+) into the cells is negligible when carried out in the presence of SeMet, or that SeMet enhances the release of MeHg(+). On the other hand, L-SeMet is directly involved in the detoxification of MeHg(+), but the involvement of D-SeMet occurs only indirectly since it has been neither identified in the medium nor in C. sorokiniana after supplementation with this enantiomer. It may be that D-SeMet is transformed into SeMeSec and L-SeMet. Moreover, SeMeSec is almost totally released from the cells after 72 hours. No mercury-selenium complex was detected but, since the summation of the different species identified accounted only for 77% of the total selenium and mercury measured directly after sample digestion, it is possible that they are present in the form of an undetected Se-Hg complex. This hypothesis is supported by the decrease of

  7. Mercury, methylmercury, and other water-quality data from flood-control impoundments and natural waters of the Red River of the North Basin, Minnesota, 1997-99

    USGS Publications Warehouse

    Brigham, Mark E.; Olson, Mark L.; DeWild, John F.

    1999-01-01

    It is now well documented that impoundment of natural waters, with inundation of terrestrial area, results in enhanced conversion of inorganic mercury to methylmercury, a form that is toxic and bioaccumulates to a greater extent than inorganic mercury. Concentrations of mercury, methylmercury, and other water-quality constituents are reported from water sampled from flood-control impoundments and natural (unimpounded) waters of the Red River of the North Basin from 1997-99.

  8. Delay, change and bifurcation of the immunofluorescence distribution attractors in health statuses diagnostics and in medical treatment

    NASA Astrophysics Data System (ADS)

    Galich, Nikolay E.; Filatov, Michael V.

    2008-07-01

    Communication contains the description of the immunology experiments and the experimental data treatment. New nonlinear methods of immunofluorescence statistical analysis of peripheral blood neutrophils have been developed. We used technology of respiratory burst reaction of DNA fluorescence in the neutrophils cells nuclei due to oxidative activity. The histograms of photon count statistics the radiant neutrophils populations' in flow cytometry experiments are considered. Distributions of the fluorescence flashes frequency as functions of the fluorescence intensity are analyzed. Statistic peculiarities of histograms set for healthy and unhealthy donors allow dividing all histograms on the three classes. The classification is based on three different types of smoothing and long-range scale averaged immunofluorescence distributions and their bifurcation. Heterogeneity peculiarities of long-range scale immunofluorescence distributions allow dividing all histograms on three groups. First histograms group belongs to healthy donors. Two other groups belong to donors with autoimmune and inflammatory diseases. Some of the illnesses are not diagnosed by standards biochemical methods. Medical standards and statistical data of the immunofluorescence histograms for identifications of health and illnesses are interconnected. Possibilities and alterations of immunofluorescence statistics in registration, diagnostics and monitoring of different diseases in various medical treatments have been demonstrated. Health or illness criteria are connected with statistics features of immunofluorescence histograms. Neutrophils populations' fluorescence presents the sensitive clear indicator of health status.

  9. Comparison of the indirect immunobead, radiolabeled, and immunofluorescence assays for immunoglobulin G serum antibodies to human sperm

    SciTech Connect

    Haas, G.G. Jr.; D'Cruz, O.J.; DeBault, L.E. )

    1991-02-01

    The relative sensitivities of the indirect immunobead test, the indirect flo cytometric immunofluorescence assay, and an indirect radiolabeled antiglobulin assay were compared. Eighteen immunobead test positive sera and 18 negative sera were used as the standard for the other two assays. Of the 18 positive sera, 14 (77%) and 5 (27%) were positive in the immunofluorescence assay and the radiolabeled antiglobulin assay, respectively. Four (22%) of the low titer immunobead test positive sera were negative by both the immunofluorescence assay and the radiolabeled antiglobulin assay. However, there was a significant positive correlation between the results of the immunofluorescence assay and the radiolabeled antiglobulin assay (r = 0.73) and between the results of the radiolabeled antiglobulin assay and the titer of the immunobead test (r = 0.82). The use of an unselected sperm population in the radiolabeled antiglobulin assay and the classical indirect immunofluorescence method using methanol-fixed sperm gave false-positive results in the radiolabeled antiglobulin assay and the immunofluorescence assay. These results suggested that immunoglobulin G antisperm antibody positive sera may be reactive both to sperm surface and internalized sperm antigens.

  10. Immunofluorescence to Monitor the Cellular Uptake of Human Lactoferrin and its Associated Antiviral Activity Against the Hepatitis C Virus.

    PubMed

    Allaire, Andréa; Picard-Jean, Frédéric; Bisaillon, Martin

    2015-01-01

    Immunofluorescence is a laboratory technique commonly used to study many aspects of biology. It is typically used to visualize the distribution and/or localization of a target molecule in cells and tissues. Immunofluorescence relies on the specificity of fluorescent-labelled antibodies against their corresponding antigens within a cell. Both direct and indirect immunofluorescence approaches can be used which rely on the use of antibodies linked with a fluorochrome. Direct immunofluorescence is less frequently used because it provides lower signal, involves higher cost and less flexibility. In contrast, indirect immunofluorescence is more commonly used because of its high sensitivity and provides an amplified signal since more than one secondary antibody can attach to each primary antibody. In this manuscript, both epifluorescence microscopy and confocal microscopy were used to monitor the internalization of human lactoferrin, an important component of the immune system, into hepatic cells. Moreover, we monitored the inhibitory potential of hLF on the intracellular replication of the Hepatitis C virus using immunofluorescence. Both the advantages and disadvantages associated with these approaches are discussed. PMID:26485289

  11. Methylmercury differentially affects GABAA receptor-mediated spontaneous IPSCs in Purkinje and granule cells of rat cerebellar slices

    PubMed Central

    Yuan, Yukun; Atchison, William D

    2003-01-01

    Using whole-cell recording techniques we compared effects of the environmental cerebellar neurotoxicant methylmercury (MeHg) on spontaneous IPSCs (sIPSCs) of both Purkinje and granule cells in cerebellar slices of the rat. In Purkinje cells, bath application of 10, 20 or 100 μM MeHg initially increased then suppressed the frequency of sIPSCs to zero. In granule cells, the initial increase in frequency was not observed in ≈50 % of cells examined, but suppression of sIPSCs by MeHg occurred in every cell tested. For both cells, time to onset of effects of MeHg was inversely related to the concentration; moreover, the pattern of changes in mIPSCs induced by MeHg in the presence of tetrodotoxin was similar to that in sIPSCs. For each concentration of MeHg, it took 2–3 times longer to block sIPSCs in Purkinje cells than it did in granule cells. MeHg also initially increased then decreased amplitudes of sIPSCs to block in both cells; again the response was more variable in granule cells. In most Purkinje and some granule cells, MeHg induced a giant, slow inward current during the late stages of exposure. Appearance of this current appeared to be MeHg concentration dependent, and the direction of current flow was reversed by changing the holding potentials. Reduction of the [Cl−] in the internal solution caused inwardly directed, but not outwardly directed giant currents to disappear, suggesting that this current is a Cl−-mediated response. However, bicuculline and picrotoxin failed to block it. MeHg apparently acts at both presynaptic and postsynaptic sites to alter GABAA receptor-mediated inhibitory synaptic transmission. GABAA receptors in granule cells appear to be more sensitive to block by MeHg than are those in Purkinje cells, although the general patterns of effects on the two cells are similar. PMID:12879869

  12. Deleterious effects in mice of fish-associated methylmercury contained in a diet mimicking the Western populations' average fish consumption.

    PubMed

    Bourdineaud, Jean-Paul; Fujimura, Masatake; Laclau, Muriel; Sawada, Masumi; Yasutake, Akira

    2011-02-01

    Methylmercury (MeHg) is a potent neurotoxin, and human beings are mainly exposed to this pollutant through fish consumption. Only a few contradictory epidemiological studies are currently available examining the impact of fish consumption on human populations. In the present study, we wanted to address whether a diet mimicking the fish consumption of Western populations could result in observable adverse effects in mice, and whether beneficial nutriments from fish were able to counterbalance the deleterious effects of MeHg, if any. In Europe and the United States, fish consumption varies widely between countries, from 11 to 100 g fish/day. A mid-range value of 25 g fish/day corresponds to a fish contribution to the total diet of 1.25% on a dry weight basis. We decided to supplement a vegetarian-based mouse diet with 1.25% of lyophilized salmon flesh (SAL diet), or 1.25% of a blend of lyophilized cod, tuna, and swordfish (CTS diet). Total mercury contents were 1.15±0.15, 2.3±0.1 and 35.75±0.15 ng Hg/g of food pellets for the control, SAL and CTS diets, respectively. After two months feeding, the CTS diet resulted in significant observable effects as compared to the control and SAL diets, encompassing decreased body growth, altered behavioral performance and increased anxiety level, modification of mitochondrial respiratory protein subunit concentrations in kidney and brain structures, modified gene expression patterns in kidneys, liver and muscles, and a decrease of dopamine concentrations in the hypothalamus and striatum. Our findings have health implications, firstly because 1.25% of CTS flesh in the diet corresponds to an average exposure to MeHg below the WHO provisory tolerable weekly intake (PTWI) (1.6 μg MeHg/kg of body weight/week), and secondly because many people in Western populations, among them women of child-bearing age, are exceeding the PTWI value (for instance, 35% of the French population inhabiting the Atlantic and Mediterranean coasts). PMID

  13. Highly multiplexed imaging of single cells using a high-throughput cyclic immunofluorescence method.

    PubMed

    Lin, Jia-Ren; Fallahi-Sichani, Mohammad; Sorger, Peter K

    2015-01-01

    Single-cell analysis reveals aspects of cellular physiology not evident from population-based studies, particularly in the case of highly multiplexed methods such as mass cytometry (CyTOF) able to correlate the levels of multiple signalling, differentiation and cell fate markers. Immunofluorescence (IF) microscopy adds information on cell morphology and the microenvironment that are not obtained using flow-based techniques, but the multiplicity of conventional IF is limited. This has motivated development of imaging methods that require specialized instrumentation, exotic reagents or proprietary protocols that are difficult to reproduce in most laboratories. Here we report a public-domain method for achieving high multiplicity single-cell IF using cyclic immunofluorescence (CycIF), a simple and versatile procedure in which four-colour staining alternates with chemical inactivation of fluorophores to progressively build a multichannel image. Because CycIF uses standard reagents and instrumentation and is no more expensive than conventional IF, it is suitable for high-throughput assays and screening applications. PMID:26399630

  14. Highly multiplexed imaging of single cells using a high-throughput cyclic immunofluorescence method

    PubMed Central

    Lin, Jia-Ren; Fallahi-Sichani, Mohammad; Sorger, Peter K.

    2015-01-01

    Single-cell analysis reveals aspects of cellular physiology not evident from population-based studies, particularly in the case of highly multiplexed methods such as mass cytometry (CyTOF) able to correlate the levels of multiple signalling, differentiation and cell fate markers. Immunofluorescence (IF) microscopy adds information on cell morphology and the microenvironment that are not obtained using flow-based techniques, but the multiplicity of conventional IF is limited. This has motivated development of imaging methods that require specialized instrumentation, exotic reagents or proprietary protocols that are difficult to reproduce in most laboratories. Here we report a public-domain method for achieving high multiplicity single-cell IF using cyclic immunofluorescence (CycIF), a simple and versatile procedure in which four-colour staining alternates with chemical inactivation of fluorophores to progressively build a multichannel image. Because CycIF uses standard reagents and instrumentation and is no more expensive than conventional IF, it is suitable for high-throughput assays and screening applications. PMID:26399630

  15. A Cross-sectional Study of Clinical, Histopathological and Direct Immunofluorescence Spectrum of Vesiculobullous Disorders

    PubMed Central

    S., Arundhathi; S., Ragunatha; K.C., Mahadeva

    2013-01-01

    Background: Accurate diagnosis of vesiculobullous lesions of skin requires evaluation of clinical, histopathologic and immunofluorescence findings. Methods: A cross-sectional study of 68 patients to evaluate the clinical, histopathological and direct immunofluorescence (DIF) features in the diagnosis of cutaneous vesiculobullous disorders. The patients with vesiculobullous lesions were subjected to clinical examination regarding socio-demographic and clinical data. Two biopsy specimens were taken, one from intact vesicle for histopathological study and another from perilesional normal looking skin or oral mucosa for DIF. Results: Vesiculobullous lesions constituted 22.08% of total number of skin biopsies. The most common clinical diagnosis was pemphigus vulgaris (PV) in 36 cases, followed by bullous pemphigoid (BP) in 8 cases, pemphigus foliaceous (PF) in 6 cases, and dermatitis herpetiformis (DH) in 4 cases. Characteristic histopathological features were present in 26 cases of PV, 9 cases of BP and 4 cases of PF, and 17.7% showed non- specific changes. DIF was positive in 24 cases of PV, 9 cases of BP and 3 cases of PF, and negative in 34.92% of cases. Conclusion: Clinical, histopathological and DIF features together or in combination help in the final diagnosis of vesiculobullous disorders. Individually, none of these methods are diagnostic in each and every case. PMID:24551638

  16. The use of Biochip immunofluorescence microscopy for the serological diagnosis of epidermolysis bullosa acquisita.

    PubMed

    Marzano, Angelo Valerio; Cozzani, Emanuele; Biasin, Matteo; Russo, Irene; Alaibac, Mauro

    2016-05-01

    Epidermolysis bullosa acquisita is a rare autoimmune bullous disease characterized by the presence of circulating antibodies directed against the collagen type VII. Diagnosis is generally based on clinical history, clinical features, histology, direct and indirect immunofluorescence, immunoblotting and ELISA. Our study aims to determine the validity of the Biochip immunofluorescence microscopy for the serological diagnosis of epidermolysis bullosa acquisita. Six patients with epidermolysis bullosa acquisita and presence of antibodies against type VII collagen confirmed by ELISA were included in the study. Subsequently, all sera of patients were analyzed using Biochip. Antibodies anti-collagen type VII were detected in all sera by means of the Biochip technology. Thus, Biochip shows a good correlation with ELISA and seems to be an appropriate method for the diagnosis of epidermolysis bullosa acquisita. It is an easy, fast and standardized method which could facilitate the diagnosis of this autoimmune bullous disease. We suggest that it could be used as an initial screening test to identify patients with epidermolysis bullosa acquisita. PMID:26895535

  17. Identification of Mesenchymal Stem Cell Marker STRO-1 in Oral Reactive Lesions by Immunofluorescence Method

    PubMed Central

    Dehghani Nazhvani, Ali; Hosseini, Seyed-Mojtaba; Tahoori, Bita; Tavangar, Maryam-Sadat; Attar, Armin

    2015-01-01

    Statement of the Problem Stem cells are considered as new implement for tissue regeneration. Several niches in adult human body are colonized by multipotent stem cells but access to these potential reservoirs is often limited. Although human dental pulp stem cells isolated from healthy teeth have been extensively characterized, it is still unknown whether stem cells also exist in reactive lesions of oral cavity such as pyogenic granuloma and peripheral ossifying fibroma which are deliberated as inflammatory proliferation of different cell families. Purpose The aim of this study was to explore for clues to see whether pyogenic granuloma or peripheral ossifying fibroma contain dental mesenchymal stem cell (DMSC). Materials and Method Four pyogenic granuloma and four peripheral ossifying fibroma specimens were collected by excisional biopsy and preserved in PBS-EDTA at -86 °C. Then we cut them in 5µm diameter using Cryostat. Having been rinsed with PBS, the samples were stained with a primary mouse anti-human STRO-1 monoclonal IgM antibody. Afterward, a secondary goat anti-mouse IgM-FITC antibody was applied to detect STRO-1+ cells as probable stem cells by immunofluorescence technique. Results Immunofluorescence microscopy revealed presence of STRO-1+ cells in these lesions, particularly localized on perivascular zone. The negative control group was not glowing. Conclusion Based on these results, it was found that reactive lesions of pyogenic granuloma and peripheral ossifying fibroma have STRO-1 positive cells, which raises the possibility that these cells may be DMSCs. PMID:26535404

  18. Indirect Immunofluorescence of Proteins in Oogenic Germ Cells of Caenorhabditis elegans.

    PubMed

    Brenner, John L; Schedl, Tim

    2016-01-01

    Formation of full-grown oocytes requires the control and coordination of a number of processes (e.g., oocyte growth) through multiple stages, where disruption at any one step can result in infertility. Numerous proteins are required for the regulation and execution of the various oogenic processes as well as functioning as maternal products needed for embryogenesis. Immunofluorescence microscopy combined with staining using antibodies against specific proteins, or their posttranslationally modified forms, is a standard approach to determine the temporal and spatial location of gene products that function in oocyte development. The simple linear organization of the germline in the model organism Caenorhabditis elegans allows easy correlation of protein localization and germ cell developmental stage, thus aiding in our understanding of protein function during gametogenesis. Here we outline co-immunofluorescence staining for two major regulators of C. elegans germline development, the translational repressor GLD-1 and activated form of MPK-1 (dpMPK-1) ERK MAP kinase in dissected gonads from adult C. elegans. Worms are first dissected and the extruded gonads are fixed and permeabilized before being bathed in primary antibodies against GLD-1 and dpMPK-1. Secondary antibodies conjugated to fluorophore dyes and that target the IgG domains of the primary antibody reagents are then used to provide a fluorescent signal that corresponds to the position of GLD-1 and dpMPK-1. The outlined procedure is amenable to many other proteins expressed in C. elegans germ cells. PMID:27557570

  19. Improved detection of lacZ reporter gene expression in transgenic epithelia by immunofluorescence microscopy.

    PubMed

    Mahony, Donna; Karunaratne, Seetha; Rothnagel, Joseph A

    2002-04-01

    The bacterial lacZ gene is commonly used as a reporter for the in vivo analysis of gene regulation in transgenic mice. However, several laboratories have reported poor detection of beta-galactosidase (the lacZ gene product) using histochemical techniques, particularly in skin. Here we report the difficulties we encountered in assessing lacZ expression in transgenic keratinocytes using classic X-gal histochemical protocols in tissues shown to express the transgene by mRNA in situ hybridization. We found that lacZ reporter gene expression could be reliably detected in frozen tissue sections by immunofluorescence analysis using a beta-galactosidase-specific antibody. Moreover, we were able to localize both transgene and endogenous gene products simultaneously using double-label immunofluorescence. Our results suggest that antibody detection of beta-galactosidase should be used to verify other assays of lacZ expression, particularly where low expression levels are suspected or patchy expression is observed. PMID:11994142

  20. Pulmonary fibrosis following pneumonia due to acute Legionnaires' disease. Clinical, ultrastructural, and immunofluorescent study.

    PubMed

    Chastre, J; Raghu, G; Soler, P; Brun, P; Basset, F; Gibert, C

    1987-01-01

    During a recent nosocomial outbreak, 20 critically ill patients with acute Legionnaires' disease were admitted to the intensive care unit of Hopital Bichat, Paris. Pulmonary specimens were obtained at surgery or immediately after death in 12 patients and were examined by light, immunofluorescent, and electron microscopy. Five of these 12 patients showed evidence of pulmonary fibrosis. In all of these five patients, infection with Legionella pneumophila was evidenced by bacteriologic methods, and other diseases known to cause fibrosis were excluded. The condition of four patients deteriorated rapidly with respiratory failure, and they died with pulmonary fibrosis. Only one patient finally recovered but was left with pulmonary sequelae. Two distinctive morphologic patterns were observed, one in which interstitial fibrosis was predominant and one in which intra-alveolar organization and fibrosis were also present. The alveolar epithelial lining and the basement membranes were disrupted in all patients, as evidenced by ultrastructural observations and by immunofluorescent studies showing gaps in the distribution of type 4 collagen and laminin. Types 1 and 3 collagen accumulated in areas corresponding to thickened interstitium and intra-alveolar fibrosis. Thus, some patients who survive the acute pneumonia of Legionnaires' disease may develop pulmonary fibrosis, and this process may lead to functional impairment or death despite prompt and appropriate treatment. PMID:3539546

  1. Original Approach for Automated Quantification of Antinuclear Autoantibodies by Indirect Immunofluorescence

    PubMed Central

    Bertin, Daniel; Jourde-Chiche, Noémie; Bongrand, Pierre

    2013-01-01

    Introduction. Indirect immunofluorescence (IIF) is the gold standard method for the detection of antinuclear antibodies (ANA) which are essential markers for the diagnosis of systemic autoimmune rheumatic diseases. For the discrimination of positive and negative samples, we propose here an original approach named Immunofluorescence for Computed Antinuclear antibody Rational Evaluation (ICARE) based on the calculation of a fluorescence index (FI). Methods. We made comparison between FI and visual evaluations on 237 consecutive samples and on a cohort of 25 patients with SLE. Results. We obtained very good technical performance of FI (95% sensitivity, 98% specificity, and a kappa of 0.92), even in a subgroup of weakly positive samples. A significant correlation between quantification of FI and IIF ANA titers was found (Spearman's ρ = 0.80, P < 0.0001). Clinical performance of ICARE was validated on a cohort of patients with SLE corroborating the fact that FI could represent an attractive alternative for the evaluation of antibody titer. Conclusion. Our results represent a major step for automated quantification of IIF ANA, opening attractive perspectives such as rapid sample screening and laboratory standardization. PMID:24454469

  2. Immunofluorescence Patterns in Selected Dermatoses, Including Blistering Skin Diseases Utilizing Multiple Fluorochromes

    PubMed Central

    Abreu-Velez, Ana Maria; Calle-Isaza, Juliana; Howard, Michael S.

    2015-01-01

    Background: Autoimmune vesiculobullous disorders represent a heterogeneous group of dermatoses whose diagnosis is made based on clinical history, histologic features, and immunopathologic features. The most commonly used techniques for the diagnosis of these diseases are direct and indirect immunofluorescence (DIF and IIF), including salt-split processing. NaCl split skin is used to determine the level of blister formation, and the localization of autoantibodies relative to the split. Classically, immunofluorescence has been performed with one fluorochrome in the diagnosis of autoimmune bullous skin diseases. Aims: To compare DIF and IIF of the skin, using a single fluorochrome versus multiple fluorochromes. Materials and Methods: We studied 20 autoimmune skin disease cases using fluorescein isothiocyanate (FITC) alone, in comparison to multiple fluorochromes (with or without DNA counterstaining). Results: The use of multiple fluorochromes helped to simultaneously visualize reactivity in multiple skin areas, in contrast to using FITC alone. Conclusions: Using multiple fluorochromes allows simultaneous labeling of two or more antigens within the same cell/or tissue section, assists in colocalization of unknown antigens with known molecules, and helps in ruling out “background” staining. PMID:26605203

  3. Intensive Immunofluorescence Staining Methods for Low Expression Protein: Detection of Intestinal Stem Cell Marker LGR5

    PubMed Central

    Yamazaki, Masaki; Kato, Atsuhiko; Zaitsu, Yoko; Watanabe, Takeshi; Iimori, Makoto; Funahashi, Shinichi; Kitao, Hiroyuki; Saeki, Hiroshi; Oki, Eiji; Suzuki, Masami

    2015-01-01

    Leucine-rich repeat-containing G-protein coupled receptor 5, or LGR5, is a molecule that recognizes stem cells in multiple organs and also in colon cancer. Previously, we have developed monoclonal antibodies specific to LGR5 protein that can be used for immunofluorescence staining, but because a very low level of LGR5 protein is expressed, the visualization technique needed to be enhanced. To develop procedures to detect LGR5 protein in various specimens by immunofluorescence staining, we evaluated the Alexa-labeled streptavidin biotin (LSAB), the Qdot, and the tyramide methods. The detection sensitivity was highest in the tyramide method followed by the Qdot method, whereas subcellular localization of the protein was most clear in the Qdot method, because the Qdot method gave a high S/N ratio that could show a low background. Thus, the tyramide method is superior to the Q-dot method for intensifying the signal of a low expression protein, and the Qdot method is superior to the tyramide method for identifying the subcellular localization of the target protein. The results of the present study will be helpful in providing more insight into the pathophysiological roles of LGR5-positive cancer stem cells and in developing therapeutic approaches for targeting cancer stem cells. PMID:26633908

  4. Incorporating rice residues into paddy soils affects methylmercury accumulation in rice.

    PubMed

    Zhu, Huike; Zhong, Huan; Wu, Jialu

    2016-06-01

    Paddy fields are characterized by frequent organic input (e.g., fertilization and rice residue amendment), which may affect mercury biogeochemistry and bioaccumulation. To explore potential effects of rice residue amendment on methylmercury (MMHg) accumulation in rice, a mercury-contaminated paddy soil was amended with rice root (RR), rice straw (RS) or composted rice straw (CS), and planted with rice. Incorporating RS or CS increased grain MMHg concentration by 14% or 11%. The observed increases could be attributed to the elevated porewater MMHg levels and thus enhanced MMHg uptake by plants, as well as increased MMHg translocation to grain within plants. Our results indicated for the first time that rice residue amendment could significantly affect MMHg accumulation in rice grain, which should be considered in risk assessment of MMHg in contaminated areas. PMID:26974480

  5. Seasonal variation of methylmercury in sediment cores from the Tagus Estuary (Portugal).

    PubMed

    Monteiro, Carlos Eduardo; Cesário, Rute; O'Driscoll, Nelson J; Nogueira, Marta; Válega, Mónica; Caetano, Miguel; Canário, João

    2016-03-15

    Seasonal and spatial variations of dissolved and particulate methylmercury were evaluated for the first time in sediment cores from the Tagus Estuary. Results showed the highest MeHg concentrations in summer months indicating that the "seasonally" methylation process occurs not only at the topmost layers of the sediments but also in the deeper layers of the sediment column. The proportion of MeHg (up to 92%) in some of our pore water samples was higher than values reported in the literature for other estuaries suggesting that the sedimentary environment in the Tagus tends to favour Hg methylation. This work points to the importance of seasonal variation of the MeHg production in sediment cores. In physically dominated estuaries this enhances seasonal MeHg production in deeper sediments that can have serious ecological impacts due to resuspension or advection processes under extreme events by the increase of MeHg transported to the water column. PMID:26851871

  6. Mercury residues in tissues of dead and surviving birds fed methylmercury

    USGS Publications Warehouse

    Finley, M.T.; Stickel, W.H.; Christensen, R.E.

    1979-01-01

    Concentrations of mercury in passerine birds fed diets containing 40 ppm methylmercury were similar in tissues of birds that died from mercury poisoning and in those that were sacrificed after half the group had died. Residues were higher in tissues of birds that died, but the differences were not statistically significant. Residue levels were highest in livers, followed by kidneys and brains. Levels of mercury were similar in breast muscle, carcass, and whole body. Mercury levels were highest in redwinged blackbirds, lowest in grackles, and intermediate in starlings and cowbirds. Mercury concentrations exceeded 20 ppm in all tissues of all species and were similar to levels reported in wild birds known to have died of mercury poisoning.

  7. Differences in methylmercury and inorganic mercury biomagnification in a tropical marine food web.

    PubMed

    Seixas, Tércia G; Moreira, Isabel; Siciliano, Salvatore; Malm, Olaf; Kehrig, Helena A

    2014-03-01

    Methylmercury (MeHg), inorganic mercury (Hginorg) and their biomagnification factors (BMF) were evaluated along a non-degraded Brazilian bay food web. Highly significant differences (p < 0.0001) were found between MeHg and Hginorg concentrations among all organisms (microplankton, shrimp, fish and dolphin). MeHg increased with increasing trophic position while Hginorg did not present the same pattern. BMF values for MeHg were higher than 1 for all trophic interactions from source to consumer, indicating that MeHg was transferred more efficiently and biomagnified over the entire web. Only one BMF exceeding one was observed for Hginorg (27) between microplankton and their consumer, planktivorous fish. BMF values for Hginorg were significantly different than those found for MeHg (20) at the base of the food web. PMID:24452478

  8. Comparative study of two chromatographic columns used in the GLC determination of methylmercury

    SciTech Connect

    Najdek, M.; Bazulic, D.

    1985-02-01

    A large effort has gone into finding an adequate analytical method for the determinations of methylmercury. Various stationary phases in GC determination have been tested. It was obvious with every method that the stationary phase had to be saturated to give a stable response without tailing the peaks or walking the retention time. To accomplish this several authors have reported treatments which included the injection of the solutions containing inorganic or organic mercuric chloride metoxyethylmercuric iodide, or large amount of potassium iodide. The authors report here a simple and efficient way to obtain satisfactory stable response from the chromatographic column based on the use of 10% diethyleneglycol adipate (DEGA) and 3% polyethyleneglycol (Carbowax 20 M).

  9. PILOT STUDY: CCQM-P39.1: As, Hg, Pb, Se and methylmercury in salmon

    NASA Astrophysics Data System (ADS)

    Aregbe, Y.; Taylor, P. D. P.

    2006-01-01

    CCQM-P39.1 was organized as a follow-up pilot study in parallel to the key comparison CCQM-K43 after the previous pilot study on tuna fish. CCQM-P39.1 was an activity of the Inorganic Analysis Working Group (IAWG) of CCQM and was coordinated by the Joint Research Centre-Institute for Reference Materials and Measurements (IRMM, Geel, Belgium) of the European Commission (EC). In CCQM-P39.1 the amount contents of As, Hg, Pb, Se and methylmercury (CH3Hg) in salmon (muscle and skin) were the measurands under investigation. Besides the national metrology institutes (NMIs) also non-IAWG members, expert laboratories for mercury and methylmercury measurements, were invited to participate in this pilot study. Results were reported by six IAWG members and six expert laboratories. During the CCQM-IAWG autumn meeting in Berlin, October 2005, it was agreed that in CCQM-K43 the KCRV is calculated as the mixture model median (MM-median) of all reported results. Therefore in CCQM-P39.1 the reported results are presented graphically with the KCRV from CCQM-K43. The reported results of the IAWG members fall within a range of +/-4% for arsenic and lead relative to the CCQM-K43 KCRV. For mercury, the spread was +/-2%, but one IAWG member reported a very large uncertainty on the measurement result. For selenium the spread of IAGW members is +/-2% deviation from the CCQM-K43 KCRV. Including the reported results from the invited expert laboratories, the spread of results increased for arsenic, lead and mercury to +/-8%. The reported results including the experts fall within a range of +/-20% for selenium and +/-30% for methylmercury. The methods applied were isotope dilution mass spectrometry (IDMS) using sector field or quadrupole inductively coupled plasma-mass spectrometry (ICP-MS), external calibration or standard addition using ICP-MS, atomic absorption spectrometry (AAS), atomic fluorescence spectrometry (AFS), atomic emission detection (AED) and electron capture detection (ECD

  10. Comparison of game-farm and wild-strain mallard ducks in accumulation of methylmercury

    USGS Publications Warehouse

    Heinz, G.H.

    1979-01-01

    The accumulation of mercury was compared in game-farm and wild-strain mallard ducks fed a diet containing 0.5 ppm mercury in the form of methylmercury dicyandiamide. There were no significant differences between the two strains in levels of mercury that accumulated in blood, kidney, liver, breast muscle, brain, eggs, or ducklings. Mercury levels in blood were significantly correlated with levels in other tissues and eggs, as were levels in down feathers of ducklings with levels in carcasses of ducklings. The results indicate that game-farm mallards are probably suitable substitutes for wild mallards in toxicological work, that blood samples can be used to estimate levels of mercury in other tissues of adults, and that down feathers are predictive of mercury levels in duckling carcasses.

  11. Effect of methylmercury on the activity of glutathione peroxidase in rat liver

    SciTech Connect

    Hirota, Y.

    1986-09-01

    The effect of methylmercury on the activity of glutathione peroxidase in rat liver was studied in vivo. A daily dose of 10mg methylmercuric chloride/kg body weight was administered subcutaneously to 15 male Wistar rats for 10 days, and the glutathione peroxidase activity in the liver was measured to compare with the control activity. A marked decrease was observed in the glutathione peroxidase activity in the experimental animals, which measured as low as 40% in comparison to that in the control animals. It can be speculated that the inhibition of glutathione peroxidase activity plays a significant role in the development of mercury toxicity and that the protective effect of selenium and vitamin E on the mercury intoxication might be partly due to preserving the glutathione peroxidase activity in the antioxidative defense mechanisms.

  12. Anaerobic oxidation of Hg(0) and methylmercury formation by Desulfovibrio desulfuricans ND132

    NASA Astrophysics Data System (ADS)

    Colombo, Matthew J.; Ha, Juyoung; Reinfelder, John R.; Barkay, Tamar; Yee, Nathan

    2013-07-01

    The transformation of inorganic mercury (Hg) to methylmercury (MeHg) plays a key role in determining the amount of Hg that is bioaccumulated in aquatic food chains. An accurate knowledge of Hg methylation mechanisms is required to predict the conditions that promote MeHg production in aquatic environments. In this study, we conducted experiments to examine the oxidation and methylation of dissolved elemental mercury [Hg(0)] by the anaerobic bacterium Desulfovibrio desulfuricans ND132. Anoxic cultures of D. desulfuricans ND132 were exposed to Hg(0) in the dark, and samples were collected and analyzed for the loss of Hg(0), formation of non-purgeable Hg, and formation of MeHg over time. We found that D. desulfuricans ND132 rapidly transformed dissolved gaseous mercury into non-purgeable Hg, with bacterial cultures producing approximately 40 μg/L of non-purgeable Hg within 30 min, and as much as 800 μg/L of non-purgeable Hg after 36 h. Derivatization of the non-purgeable Hg in the cell suspensions to diethylmercury and analysis of Hg(0)-reacted D. desulfuricans ND132 cells using X-ray absorption near edge structure (XANES) spectroscopy demonstrated that cell-associated Hg was dominantly in the oxidized Hg(II) form. Spectral comparisons and linear combination fitting of the XANES spectra indicated that the oxidized Hg(II) was covalently bonded to cellular thiol functional groups. MeHg analyses revealed that D. desulfuricans ND132 produced up to 118 μg/L of methylmercury after 36 h of incubation. We found that a significant fraction of the methylated Hg was exported out of the cell and released into the culture medium. The results of this work demonstrate a previously unrecognized pathway in the mercury cycle, whereby anaerobic bacteria produce MeHg when provided with dissolved Hg(0) as their sole Hg source.

  13. Toxic effects of dietary methylmercury on immune system development in nestling American kestrels (Falco sparverius)

    USGS Publications Warehouse

    Fallacara, Dawn M.; Halbrook, Richard S.; French, John B.

    2011-01-01

    This study evaluated the effects of dietary methylmercury (MeHg) on immune system development in captive-reared nestling American kestrels (Falco sparverius) to determine whether T cell–mediated and antibody-mediated adaptive immunity are targets for MeHg toxicity at environmentally relevant concentrations. Nestlings received various diets, including 0 (control), 0.6, and 3.9 μg/g (dry wt) MeHg for up to 18 d posthatch. Immunotoxicity endpoints included cell-mediated immunity (CMI) using the phytohemagglutinin (PHA) skin-swelling assay and antibody-mediated immune response via the sheep red blood cell (SRBC) hemagglutination assay. T cell– and B cell–dependent histological parameters in the spleen, thymus, and bursa of Fabricius were correlated with the functional assays. For nestlings in the 0.6 and 3.9 μg/g MeHg groups, CMI was suppressed by 73 and 62%, respectively, at 11 d of age. Results of this functio