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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

    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

  8. 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

  9. 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.

  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

    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.

  6. 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.

  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. 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

  17. 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

  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. 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

  1. 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

  2. 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

  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

    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

  9. 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.

  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. 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

  13. 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

  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. 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)

  5. 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

  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. 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.

  20. 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.

  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. 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

  4. 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

  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. 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

  10. 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

  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. 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.

  14. 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.

  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. 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

  2. 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

  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. 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,...

  5. 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...

  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. 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.

  11. 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...

  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. 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

  17. 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

  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. 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

  2. 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

  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. 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.

  7. 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

  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. 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

  19. 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.

  20. 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.

  1. 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...

  2. 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.

  3. 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 ...

  4. 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

  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

    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

  17. 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

  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. 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

  4. 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 ...

  5. 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

  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. 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

  17. 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

  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. 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

  6. 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

  7. 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

  8. 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

  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