Influência de alguns fatores ambientais sobre o nível de mercúrio em Cichla spp. e Hoplias malabaricus na bacia do rio Negro

O mercúrio (Hg) é um metal pesado que bioacumula-se nos seres vivos e é tóxico ao homem. A contaminação ambiental pelo Hg na Amazônia vem sendo estudada predominantemente em áreas de garimpo, mas pouco se sabe sobre a sua dinâmica natural e os fatores que afetam sua bioacumulação na região. O objetivo deste trabalho foi investigar a influência do pH, do carbono orgânico dissolvido na água e da presença de sítios de metilação (áreas alagadas e solos hidromórficos) sobre a bioacumulação de Hg em peixes predadores da bacia do rio Negro. A interrelação entre as variáveis ambientais também foi analisada. Duas espécies com hábitos sedentários - traíra (Hoplias malabaricus) e tucunaré (Cichla spp.) foram utilizadas como bioindicadores. Foram feitas medidas de pH, COD, oxigênio e condutividade da água e coletados peixes de 33 locais da bacia do rio Negro entre o rio Uapés e Manaus, durante o período de 8 de setembro a 20 de novembro de 1999. Foram estimadas também a porcentagem de áreas alagadas e a porcentagem de solos hidromórficos da bacia de drenagem a montante do ponto de coleta. A concentração de COD correlacionou­ se negativamente com o pH (Pearson: r = -0,473, P = 0,032) e positivamente com a condutividade (Pearson: r = 0,729, P = 0.000). O COD teve uma relação fraca (r² = 0,293) com os solos hidromórficos (p = 0,002) e não foi influenciado pelas áreas alagáveis, sugerindo que estas não eram as principais fontes do carbono. Não houve correlação entre as demais variáveis ambientais e nem destas com o tamanho dos peixes. A concentração média de Hg total das traíras foi de 0,35 ppm (DP = 0,25) e a dos tucunarés 0,337 ppm (DP = 0,244). 29% das traíras e 18% dos tucunarés apresentaram concentrações acima do limite máximo recomendado para consumo pela Organização Mundial da Saúde de 0,5 ppm. A concentração de Hg aumentou significativarnente com o comprimento padrão de Hoplias malabaricus (r = 0,371, P = 0,000) e Cichla spp. (r = 0,655, p = 0,000). A traíra foi mais afetada por fatores ambientais (pH, COD, porcentagem de áreas alagadas) e mostrou-se um melhor bioindicador de contaminação local do que o tucunaré. Quanto maior a porcentagem de áreas alagáveis, maior foi a concentração de Hg na traíra (p = 0.006) e no tucunaré (p = 0,000). Estas áreas podem ser sítios de metilação e fonte de Hg quando alagadas e sua presença parece ser o fator ambiental mais importante influindo na bioacumulação do Hg. O COD teve influência positiva sobre o Hg da traíra (p = 0,029), provavelmente por carreá-lo dos solos para a água. Ao contrário do observado em lagos de regiões temperadas, o pH teve influência positiva sobre a bioacumulação do Hg na traíra (p = 0,007). A influência do pH e do COD sonbre a concentração de Hg no tucunaré não foi significativa (p = 0,452 e p = 0,381) mas as tendências foram as mesmas que as da traíra. Os solos hidromórficos não influenciaram na concentração de Hg dos peixes. O tamanho, a porcentagem de áreas alagadas, o pH e o COD explicaram a maior parte da variação na concentração do Hg (r² = 0.83), mas é preciso fazer mais estudos pois ainda existem outros fatores influindo na sua bioacumulação do Hg neste sistema

Carbon dioxide and methane emissions from interfluvial wetlands in the upper Negro River basin, Brazil

Extensive interfluvial wetlands occur in the upper Negro River basin (Brazil) and contain a mosaic of vegetation dominated by emergent grasses and sedges with patches of shrubs and palms. To characterize the release of carbon dioxide and methane from these habitats, diffusive and ebullitive emissions and transport through plant aerenchyma were measured monthly during 2005 in permanently and seasonally flooded areas. CO2 emissions averaged 2193 mg C m-2 day-1. Methane was consumed in unflooded environments and emitted in flooded environments with average values of -4.8 and 60 mg C m-2 day-1, respectively. Bubbles were emitted primarily during falling water periods when hydrostatic pressure at the sediment-water interface declined. CO2 and CH4 emissions increased when dissolved O2 decreased and vegetation was more abundant. Total area and seasonally varying flooded areas for two wetlands, located north and south of the Negro River, were determined through analysis of synthetic aperture radar and optical remotely sensed data. The combined areas of these two wetlands (3000 km2) emitted 1147 Gg C year-1 as CO2 and 31 Gg C year-1 as CH4. If these rates are extrapolated to the area occupied by hydromorphic soils in the upper Negro basin, 63 Tg C year-1 of CO2 and 1.7 Tg C year-1 as CH4 are estimated as the regional evasion to the atmosphere. © 2010 The Author(s)

Sensory subtypes in children with autism spectrum disorder: latent profile transition analysis using a national survey of sensory features

Sensory features are highly prevalent and heterogeneous among children with ASD. There is a need to identify homogenous groups of children with ASD based on sensory features (i.e., sensory subtypes) to inform research and treatment

Cortical brain abnormalities in 4474 individuals with schizophrenia and 5098 control subjects via the enhancing neuro Imaging genetics through meta analysis (ENIGMA) Consortium

BACKGROUND: The profile of cortical neuroanatomical abnormalities in schizophrenia is not fully understood, despite hundreds of published structural brain imaging studies. This study presents the first meta-analysis of cortical thickness and surface area abnormalities in schizophrenia conducted by the ENIGMA (Enhancing Neuro Imaging Genetics through Meta Analysis) Schizophrenia Working Group. METHODS: The study included data from 4474 individuals with schizophrenia (mean age, 32.3 years; range, 11-78 years; 66% male) and 5098 healthy volunteers (mean age, 32.8 years; range, 10-87 years; 53% male) assessed with standardized methods at 39 centers worldwide. RESULTS: Compared with healthy volunteers, individuals with schizophrenia have widespread thinner cortex (left/right hemisphere: Cohen's d = -0.530/-0.516) and smaller surface area (left/right hemisphere: Cohen's d = -0.251/-0.254), with the largest effect sizes for both in frontal and temporal lobe regions. Regional group differences in cortical thickness remained significant when statistically controlling for global cortical thickness, suggesting regional specificity. In contrast, effects for cortical surface area appear global. Case-control, negative, cortical thickness effect sizes were two to three times larger in individuals receiving antipsychotic medication relative to unmedicated individuals. Negative correlations between age and bilateral temporal pole thickness were stronger in individuals with schizophrenia than in healthy volunteers. Regional cortical thickness showed significant negative correlations with normalized medication dose, symptom severity, and duration of illness and positive correlations with age at onset. CONCLUSIONS: The findings indicate that the ENIGMA meta-analysis approach can achieve robust findings in clinical neuroscience studies; also, medication effects should be taken into account in future genetic association studies of cortical thickness in schizophrenia

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

The genetic architecture of the human cerebral cortex

The cerebral cortex underlies our complex cognitive capabilities, yet little is known about the specific genetic loci that influence human cortical structure. To identify genetic variants that affect cortical structure, we conducted a genome-wide association meta-analysis of brain magnetic resonance imaging data from 51,665 individuals. We analyzed the surface area and average thickness of the whole cortex and 34 regions with known functional specializations. We identified 199 significant loci and found significant enrichment for loci influencing total surface area within regulatory elements that are active during prenatal cortical development, supporting the radial unit hypothesis. Loci that affect regional surface area cluster near genes in Wnt signaling pathways, which influence progenitor expansion and areal identity. Variation in cortical structure is genetically correlated with cognitive function, Parkinson's disease, insomnia, depression, neuroticism, and attention deficit hyperactivity disorder

Fatores que influem na emissão de CO2 e CH4 em áreas alagáveis interfluviais do médio Rio Negro

Wetlands in the Amazon basin have been shown to be a globally significant source of methane and carbon dioxide, important greenhouse gases. However interfluvial savanna wetlands of Negro River basin have not been characterized. Here we describe the hydrometeorology and their influence on emissions of CO2 and CH4 from these wetlands to improve regional emission estimations. Water level and rain fall were daily measured in three wetlands and also in Aracá and Negro rivers. In two of these wetlands, one permanently flooded (RNL) and one seasonally flooded (Itu), oxygen profiles of water column, surficial temperature, depth and CO2 and CH4 fluxes were monthly measured from February 2005 to January 2006. Fluxes were measured by terrestrial chambers when soil was dry and by funnels and flooding chambers when it was flooded and also estimate by Fick´s low. To estimate emissions of both wetlands, inundation models were developed for these two wetlands using temporal sequences of C-band radar images taken during 2004 and 2005. The thirst wetland (Aracá), a savanna with limited access, was sampled only at July, August and November of 2005 and their CO2 and CH4 emissions were estimate by Fick´s low. Local, habitat, depth, variations in water table level, oxygen concentration and surface water temperature were related to diffusive emissions from tree sites and ebullitive emissions from RNL and Itu site. The existence of methane transport through grass parenchyma was investigated in these two wetlands using paired emission measurements with and without grasses and a paired T-test of Student. All wetlands were very shallow, with maximum depth of 1.8 m. Rain fall was higher in May and lesser in October in all wetlands. Wetland water table was influenced daily by rain fall and seasonally by water level of nearest river in all wetlands. Total area calculated for RNL field was 1685 km2 and for Itu field was 1295 km2. Yearly, about 52% of the area of both wetlands was inundated. Oxygen concentrations fell with depth but the hypolimnion was never anoxic. The average surface temperature was 28°C. The average ebullitive CO2 emission rate for RNL and Itu sites was 11 (±11) mg CO2 m-2d-1. Diffusive CO2 average for all tree sites was 7729 (±5198) mg CO2 m-2d-1. CO2 diffusive and ebullitive emissions were higher in the RNL site, and into witch site in higher density vegetation habitats. Bubble CH4 emissions were higher in RNL site and when water table was falling. There was diffusive emission of 26 mg CH4 m-2d-1 in wet environments and absorption of 5 mg CH4 m-2d-1 in dry environments. In Itu site, where emergent plants were totally rooted in soil, emission was higher in presence of emergent plants (pared T-test: n = 38; p = 0.0134), with an emission of CH4 thought parenchyma of 7 mg CH4 m-2d-1. Diffusive and ebullitive fluxes of CO2 and of CH4 were higher when dissolved oxygen in water was depleted (p < 0.05). Space temporal integration shows emissions were higher in May, when most of these wetlands areas were flooded. It was estimated Amazon interfluvial wetlands emit 56 Tg C y-1 de CO2 e de 1.5 Tg C y-1 de CH4. Total emission of methane per area was lower in interfluvial wetlands than in river floodplains. The permanent flooded field emitted 15 Mg C km-2y-1 and the seasonally flooded Field emit 4.1 Mg C km-2y-1de CH4. These results show it is necessary to recalculate methane emission estimated before for Amazon wetlands to correct overestimation.Áreas alagadas da Amazônia são fontes significativas de gás carbônico (CO2) e de metano (CH4), importantes gases de efeito estufa. No entanto áreas alagáveis interfluviais do Rio Negro ainda não foram estudadas. Este estudo contribuiu para descrever a dinâmica hidrometeorológica e sua influência sobre a emissão de CO2 e CH4 nestas áreas a fim de melhorar as estimativas de emissão regionais. Foram feitas medidas diárias de cota e pluviosidade em três campos interfluviais e nos rios Negro e Aracá. Para dois destes campos, um permanentemente inundado (RNL) e outro sazonalmente inundado (Itu), foram feitas medidas mensais de profundidade, temperatura e de perfis de oxigenação da coluna da água e de fluxos de CO2 e de CH4 entre fevereiro de 2005 e janeiro de 2006.. Os fluxos foram medidos com câmaras terrestres quando o ambiente estava seco e com funis invertidos e câmaras flutuantes quando o ambiente estava alagado, além de serem estimados pela lei de Fick. A fim de estimar a emissão destes dois campos, modelos de inundação foram desenvolvidos com uma série temporal de imagens de radar banda C tomadas em 2004 e 2005 O terceiro campo (Aracá), que era uma savana de acesso limitado, foi amostrado apenas nos meses de julho, agosto e novembro de 2005 e a emissão difusiva de CO2 e CH4 foi calculada pela lei de Fick. Local, tipo de habitat, profundidade, variação da cota, temperatura e do oxigênio dissolvido na água foram relacionadas às emissões difusivas de gases dos três campos e às emissões ebulitivas dos campos RNL e Itu. A influência da presença de plantas emergentes que podem transportar metano pelo parênquima foi testada nestes dois campos com Teste T de Student pareado. Os três campos eram rasos e apresentaram profundidade máxima de 1,8 m. As maiores precipitações ocorreram em maio e as menores em outubro em todos os campos. A cota dos três campos foi influenciada pela precipitação diária e também variou sazonalmente com a cota dos rios mais próximos. A área total do campo RNL foi calculada em 1685 km2 e a do campo Itu em 1295 km2, ambos com inundação anual média de suas áreas de 52%. O oxigênio dissolvido na água diminuiu com a profundidade, mas não houve formação de hipolímnio anóxico. A emissão média de CO2 por ebulição foi de 11(±11) mg CO2 m-2 d-1. A emissão difusiva média de CO2 foi de 7729 (±5198) mg CO2 m-2 d-1 e foi maior no campo RNL e, dentro de cada campo, aumentou com o aumento da densidade da vegetação. A emissão ebulitiva de CH4 foi maior no campo RNL e era maior quando a cota dos campos estava caindo. Houve emissão média de 26 mg CH4 m-2d-1 por difusão em ambientes alagados e consumo médio de 5 mg CH4 m-2d-1 em ambientes secos. No campo Itu, onde as raízes das plantas eram totalmente implantadas no solo, houve maior emissão de CH4 na presença de plantas emergentes (teste T pareado: n = 38; p = 0,0134), com um transporte médio de 7 mg CH4 m-2 d-1 através do parênquima. As emissões difusiva e ebulitiva de CO2 e de CH4 foram maiores quando havia menos oxigênio dissolvido na água (p < 0,05). A integração espaço-temporal dos dados mostrou que os campos emitiram mais gases em maio, quando havia uma maior área alagada. Estimou-se uma emissão total das campinas da Amazônia Legal de 56 Tg C ano-1 de CO2 e de 1,5 Tg C ano-1 de CH4. A emissão total anual de metano por unidade de área foi menor que nas planícies aluviais. O campo permanentemente inundado emitiu 15 Mg C km-2 ano-1 e o campo sazonalmente inundado emitiu 4,1 Mg C km-2ano-1de CH4. Estes resultados demonstraram que é necessário rever as estimativas pretéritas de emissão de metano feitas para toda a Amazônia a fim de corrigir a superestimação causada pela extrapolação de dados de emissão das planícies aluviais para as áreas interfluviais

Aspectos da biologia e da descrição e Benthana picta (Brandt, 1833), (Crustacea, oniscidea)

Orientador: Jayme de Loyola e SilvaMonografia (Bacharelado) - Universidade Federal do Paraná. Setor de Ciencias Biológicas. Curso de Graduaçao em Ciencias Biológica

Factors controlling Hg levels in two predatory fish species in the Negro river basin, Brazilian Amazon

A number of environmental factors have been shown to influence the dynamics of Hg in aquatic ecosystems. Here we investigate the influence of fish size, pH, dissolved organic carbon (DOC), and the availability of potential methylation sites (floodplain forests and hydromorphic soils) on the concentration of total Hg in two carnivorous fishes: Cichla spp. and Hoplias malabaricus in the Negro River, Brazil. Fish and water samples for chemical analysis were collected from 33 sites in the Negro basin. The percentage of alluvial floodplains and hydromorphic soils (potential methylation sites) in the drainage basin upstream from each sampling point was estimated from radar imagery and existing soil maps with GIS. The average of Hg concentrations were 0.337 ppm (SD = 0.244) in Cichla spp. and 0.350 ppm (SD = 0.250) in H. malabaricus. Although the study area was geographically isolated from most major anthropogenic Hg sources, over 18% of Cichla spp. and 29% of H. malabaricus had Hg concentrations above 0.5 ppm, indicating naturally high background levels of Hg. Hg concentrations increased with size in both Cichla spp. (r2 = 0.664, p = 0.000) and H. malabaricus (r2 = 0.299, p = 0.000). Hg concentrations in H. malabaricus also increased with percent floodable area (p = 0.006), pH (p = 0.000) and DOC (0,063). In Cichla spp, Hg increased only in relation to percent floodable area (p = 0.000). Hydromorphic soils did not influence fish Hg. © 2006 Elsevier B.V. All rights reserved

Mercury bioacumulation in four tissues of Podocnemis erythrocephala (Podocnemididae: Testudines) as a function of water parameters

A number of environmental factors influence the dynamics of Hg in aquatic ecosystems, yet few studies have examined these factors for turtles, especially from South America. Red-headed river turtle (Podocnemis erythrocephala) is easy to capture in the black waters of Rio Negro, making it the turtle species that is consumed most often by people of the region. In this study, environmental factors and turtle size were investigated to determine their influence on the Hg concentration in blood, muscle, liver and carapace of the red-headed river turtle. Factors investigated included turtle length, pH, dissolved organic carbon and availability of potential methylation sites (floodplain forests and hydromorphic soils). The study was conducted in the Rio Negro basin, where we collected water and turtle blood, muscle, liver and carapace samples from 12 tributaries for chemical analysis. Through radar imagery and existing soil maps with GIS, the percentage of alluvial floodplains and hydromorphic soils (potential methylation sites) was estimated for each drainage basin at sampling points. The mean Hg concentration in blood of P. erythrocephala was 1.64 ng g- 1 (SD = 1.36), muscle 33 ng g- 1 (SD = 11), liver 470 ng g- 1 (SD = 313) and carapace 68 ng g- 1 (SD = 32). Sex or length did not influence the Hg concentration in P. erythrocephala blood, muscle and liver, but Hg increased in carapace tissue when length size increased (ANCOVA p = 0.007). In the multiple regression analysis, none of the environmental factors studied had a significant relation with blood, muscle, liver and carapace. P. erythrocephala moves among habitats and in the open and interconnected aquatic systems of the Amazon basin, characterized by high levels of limnological variability, a good bioindicator of Hg concentration needs to be relatively sedentary to represent a specific habitat. However, the levels of Hg in liver were sufficient to pose a potential risk to humans that consume them, suggesting the usefulness of P. erythrocephala as a bioindicator. © 2008 Elsevier B.V