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1.
Environ Sci Technol ; 48(19): 11629-36, 2014 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-25187975

RESUMO

In 2012, Arctic cod (Boreogadus saida) were collected from offshore regions of the Beaufort Sea to determine the concentrations of CYP1A1 phase I metabolites of polycyclic aromatic hydrocarbons (OH-PAHs) in liver and to correlate measured concentrations with (i) morphometric measurements that are known to be indicative of fish health and, (ii) biochemical end points of health including vitamin A/E and metabolites and hepatic deiodinase activity (DI). Four ring OH-PAHs were detected in 90% of our samples with a mean liver concentration of 1829.2 ± 159.2 ng/g (ww). Total (∑) concentrations of 5/6-membered ring OH-PAHs in liver were smaller [mean of 931.6 ± 104.3 ng/g, (ww)] and detected less frequently (75%) than the 4-ring OH-PAHs. Fish length and liver weight were both negatively correlated to ∑ concentrations of 4-ringed OH-PAHs (p < 0.001). Liver somatic index was also negatively correlated to ∑4-OH-PAHs (p < 0.05) but not for ∑5/6-OH-PAHs (p > 0.1). There was a significant positive relationship between DI and 4-ring OH-PAHs (p < 0.05) in liver, suggesting an induction of this enzyme. No such correlation was observed for the 5/6-ring OH-PAHs. Retinyl palmitate (RP) was the only vitamin that could be measured in liver ranging from 0.230 to 26.3 ug/g (ww). No associations between RP and levels of the 4- or 5/6-ringed OH-PAHs were observed. Continued baseline studies are clearly warranted to further understand effects of OH-PAHs on fish health before planned exploration activities begin in this region.


Assuntos
Monitoramento Ambiental , Gadiformes , Hidrocarbonetos Policíclicos Aromáticos/análise , Poluentes Químicos da Água/análise , Alaska , Animais , Canadá , Citocromo P-450 CYP1A1/metabolismo , Diterpenos , Geografia , Iodeto Peroxidase/metabolismo , Fígado/química , Fígado/efeitos dos fármacos , Oceanos e Mares , Valores de Referência , Ésteres de Retinil , Vitamina A/análogos & derivados , Vitamina A/química
2.
Am J Trop Med Hyg ; 2024 Jul 16.
Artigo em Inglês | MEDLINE | ID: mdl-39013374

RESUMO

Lymphedema (LE) is one the most disfiguring chronic manifestations of lymphatic filariasis. Its management relies primarily on limb hygiene and local care. A previous study in Ghana demonstrating a beneficial effect of doxycycline on LE led to the current multicenter trial on the efficacy of doxycycline in filarial LE. A randomized placebo-controlled trial was initiated in two rural health districts in Mali. Patients with LE stages 1-3 were randomized to receive either doxycycline (200 mg/day) or placebo over a 6-week monitored treatment period and were then followed every 6 months for 2 years. Both groups received materials for limb hygiene that was carried out daily for the entire 2-year study. The primary endpoint was lack of progression in LE stage at 24 months. One hundred patients were enrolled in each study arm. The baseline sociodemographic characteristics of each group were largely similar. There was no significant difference at month 24 after treatment initiation in the number of subjects showing progression in LE stage between the two treatment arms (P = 0.5921). Importantly, however, the number of attacks of acute adenolymphangitis (ADLA) was reduced in both arms, but there was no significant difference between the two groups at any follow-up time point (all P >0.23). Doxycycline was well tolerated in those receiving the drug. When added to daily self-administered limb hygiene, a 6-week course of doxycycline (200 mg) was not superior to placebo in increasing the improvement associated with hygiene alone in LE volume, stage, or frequency of ADLA attacks over a 24-month period.

3.
Harmful Algae ; 127: 102474, 2023 08.
Artigo em Inglês | MEDLINE | ID: mdl-37544674

RESUMO

This study presents the first evidence that a diverse suite of phycotoxins is not only being actively produced by the toxigenic algal communities in the Canadian Arctic waters, but is also entering the marine food web. We detected measurable amounts of Amnesic Shellfish Toxins (ASTs) and Paralytic Shellfish Toxins (PSTs), as well as trace amounts of other lipophilic toxin groups including pectenotoxins, yessotoxins, and cyclic imines, in bivalves collected from the Canadian Beaufort Sea in 2014 and 2018. There appear to be species-specific differences in accumulation and retention of AST by Arctic bivalves, with significantly higher concentrations recorded in Nuculanidae than Propeamussiidae, likely reflecting physiological and allometric differences. We further confirm the omnipresence of potentially toxic taxonomically-versatile phytoplankton communities in the western Canadian Arctic comprising Pseudo-nitzschia delicatissima group, P. obtusa, Dinophysis acuminata, Prorocentrum minimum, Alexandrium tamarense, and Gymnodinium spp. Although measurements of actual toxicity levels and profiles of these species at the time of sampling fall outside of the scope of this study, we show that high abundance and competitive success of known AST-producers, Pseudo-nitzschia spp., are possible in Canadian Arctic waters. In 2014, a strong dominance of Pseudo-nitzschia spp. was observed at a few shallow coastal stations, representing nearly 40% of the total phytoplankton cell abundances with > 106 cells/L at the depth of maximum chlorophyll a. We further describe oceanographic conditions conducive to high abundances of toxin-producing algae, indicating that temperature is likely a key factor. Even though measured AST and PST concentrations in bivalve tissue remained well below the Health Canada's levels at which monitored fisheries would close, i.e., 5% and 4%, respectively, their presence demonstrate that phycotoxin accumulation is occurring in food webs of the Canadian Beaufort Sea. Yet, the phycotoxin production controls and trophic transfer mechanisms remain unknown. Canadian Arctic marine ecosystems are rapidly changing and temperatures are expected to continue to increase. Given that these changes simultaneously affect multiple, and often co-occurring, species of primary producers, adaptive capacity is likely to play an important role in the structure of phytoplankton communities in the Canadian Arctic.


Assuntos
Bivalves , Diatomáceas , Animais , Toxinas Marinhas/toxicidade , Ecossistema , Clorofila A , Canadá , Fitoplâncton
4.
Am J Trop Med Hyg ; 104(6): 2298-2304, 2021 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-33901001

RESUMO

Mapping is a prerequisite for effective implementation of interventions against neglected tropical diseases (NTDs). Before the accelerated World Health Organization (WHO)/Regional Office for Africa (AFRO) NTD Mapping Project was initiated in 2014, mapping efforts in many countries were frequently carried out in an ad hoc and nonstandardized fashion. In 2013, there were at least 2,200 different districts (of the 4,851 districts in the WHO African region) that still required mapping, and in many of these districts, more than one disease needed to be mapped. During its 3-year duration from January 2014 through the end of 2016, the project carried out mapping surveys for one or more NTDs in at least 2,500 districts in 37 African countries. At the end of 2016, most (90%) of the 4,851 districts had completed the WHO-required mapping surveys for the five targeted Preventive Chemotherapy (PC)-NTDs, and the impact of this accelerated WHO/AFRO NTD Mapping Project proved to be much greater than just the detailed mapping results themselves. Indeed, the AFRO Mapping Project dramatically energized and empowered national NTD programs, attracted donor support for expanding these programs, and developed both a robust NTD mapping database and data portal. By clarifying the prevalence and burden of NTDs, the project provided not only the metrics and technical framework for guiding and tracking program implementation and success but also the research opportunities for developing improved diagnostic and epidemiologic sampling tools for all 5 PC-NTDs-lymphatic filariasis, onchocerciasis, schistosomiasis, soil-transmitted helminthiasis, and trachoma.


Assuntos
Doenças Negligenciadas/classificação , Doenças Negligenciadas/epidemiologia , Medicina Tropical , Organização Mundial da Saúde , África/epidemiologia , Filariose Linfática/epidemiologia , Filariose Linfática/prevenção & controle , Helmintíase/epidemiologia , Helmintíase/prevenção & controle , Humanos , Doenças Negligenciadas/prevenção & controle , Oncocercose/epidemiologia , Oncocercose/prevenção & controle , Prevalência , Esquistossomose/epidemiologia , Esquistossomose/prevenção & controle , Solo/parasitologia , Tracoma/epidemiologia , Tracoma/prevenção & controle
5.
Parasit Vectors ; 13(1): 155, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-32228663

RESUMO

BACKGROUND: As new lymphatic filariasis infections are eliminated through mass chemotherapy, previously affected individuals are left with the sequellae, especially chronic progressive lymphoedema. Currently this is managed by careful attention to limb hygiene to prevent infection. Studies over the past 15 years have suggested that the incorporation of doxycycline treatment may arrest or even reverse progression of lymphoedema. Most of this work has been observational or based on small studies, and if this intervention is effective, studies need to be conducted on a larger scale and under diverse geographical and social conditions before it can be incorporated into treatment policy. METHODS/DESIGN: The double-blind, placebo-controlled study was designed to investigate the impact of six weeks treatment with doxycycline added to standard limb hygiene on early stage filarial lymphoedema in five sites in Africa and the Indian subcontinent. One site in Cameroon is selected for studying lymphoedema in podoconiosis. Each site was individually powered with the potential to undertake a meta-analysis on completion. Evaluation methods followed those used in Ghana in 2012 with additions resulting from advances in technology. The details of the core protocol and how it was varied to take account of differing situations at each of the sites are provided. The study will enrol up to 1800 patients and will complete in mid-2021. CONCLUSIONS: This paper provides details of what challenges were faced during its development and discusses the issues and how they were resolved. In particular, the reasons for inclusion of new technology and the problems encountered with the supply of drugs for the studies are described in detail. By making these details available, it is hoped that the study protocol will help others interested in improving treatment for filarial lymphoedema in the design of future studies. Trial registration India: Clintrials.gov. NCT02929121 registered 10 Oct 2016: https://clinicaltrials.gov/ct2/show/NCT02929121 Mali: Clintrials.gov. NCT02927496 registered 7 Oct 2016: https://clinicaltrials.gov/ct2/show/NCT0292749 Sri Lanka: Clintrials.gov. NCT02929134 registered 10 Oct 2016: https://clinicaltrials.gov/ct2/show/NCT02929134 Ghana: ISRCTN. 14042737 registered 10 July 2017: https://doi.org/10.1186/ISRCTN14042737 Tanzania: ISRCTN. 65756724 registered 21 July 2017: https://doi.org/10.1186/ISRCTN65756724 Cameroon: ISRCTN. 1181662 registered 25 July 2017: https://doi.org/10.1186/ISRCTN11881662.


Assuntos
Doxiciclina , Filariose Linfática , Elefantíase , Linfedema , Humanos , Camarões , Doença Crônica , Método Duplo-Cego , Doxiciclina/provisão & distribuição , Doxiciclina/uso terapêutico , Elefantíase/tratamento farmacológico , Filariose Linfática/tratamento farmacológico , Gana , Higiene , Índia , Linfedema/tratamento farmacológico , Mali , Sri Lanka , Tanzânia
6.
Physiol Biochem Zool ; 91(2): 788-796, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29315031

RESUMO

Accumulation of trimethylamine N-oxide (TMAO) by deep-sea animals is proposed to protect proteins against the destabilizing effects of high hydrostatic pressure (the piezolyte hypothesis). Chondrichthyan fishes (sharks, rays, and chimaeras) provide a unique test of this hypothesis because shallow-living species have elevated TMAO levels to counteract the destabilizing effects of high urea levels accumulated for osmoregulation. Limited interspecific studies of chondrichthyans reveal that increasing depth correlates with decreased urea and increased TMAO levels, suggesting a dynamic balance between destabilizing forces on proteins (high urea, hydrostatic pressure) and TMAO to counteract these forces. Indeed, an inability to minimize urea levels or maximize TMAO levels has been proposed to explain why chondrichthyans are absent in the vast abyssal region. An unresolved question is whether the depth-related changes in chondrichthyan osmolytes are a flexible response to depth or whether phylogenetic differences in species-specific physiological set points for osmolytes account for the differences seen with depth. Sampling Arctic skates (Amblyraja hyperborea) across a 1,015-m depth gradient in the Beaufort Sea, we measured organic osmolytes in muscle using spectrophotometry and high-performance liquid chromatography. We found that the urea-to-TMAO ratio decreased linearly with depth, with tighter correlation than that seen in interspecific studies. Minor osmolytes, including betaine, sarcosine, and some α-amino acids, also declined with depth, apparently replaced (as with urea) by TMAO (a stronger piezolyte than those solutes). These data provide the first intraspecific evidence that flexible adjustments of osmolyte combinations are a key response for deep-sea living in individual chondrichthyans, supporting the piezolyte hypothesis.


Assuntos
Adaptação Fisiológica/fisiologia , Osmorregulação/fisiologia , Rajidae/fisiologia , Animais , Regiões Árticas , Pressão Hidrostática , Oceanos e Mares
7.
Am J Trop Med Hyg ; 92(5): 959-66, 2015 May.
Artigo em Inglês | MEDLINE | ID: mdl-25758650

RESUMO

Implementation of mass drug administration (MDA) with ivermectin plus albendazole (ALB) for lymphatic filariasis (LF) has been delayed in central Africa because of the risk of serious adverse events in subjects with high Loa loa microfilaremia. We conducted a community trial to assess the impact of semiannual MDA with ALB (400 mg) alone on LF and soil-transmitted helminth (STH) infections in the Republic of Congo. Evaluation at 12 months showed that ALB MDA had not significantly reduced Wuchereria bancrofti antigenemia or microfilaria (mf) rates in the community (from 17.3% to 16.6% and from 5.3% to 4.2%, respectively). However, the geometric mean mf count in mf-positive subjects was reduced from 202.2 to 80.9 mf/mL (60% reduction, P = 0.01). The effect of ALB was impressive in 38 subjects who were mf-positive at baseline and retested at 12 months: 37% had total mf clearance, and individual mf densities were reduced by 73.0%. MDA also dramatically reduced the hookworm infection rate in the community from 6.5% to 0.6% (91% reduction), with less impressive effects on Ascaris and Trichuris. These preliminary results suggest that semiannual community MDA with ALB is a promising strategy for controlling LF and STH in areas with coendemic loiasis.


Assuntos
Albendazol/uso terapêutico , Anti-Helmínticos/uso terapêutico , Filariose Linfática/tratamento farmacológico , Helmintíase/tratamento farmacológico , Wuchereria bancrofti/isolamento & purificação , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Antígenos de Helmintos/imunologia , Ascaríase/tratamento farmacológico , Ascaríase/epidemiologia , Ascaris lumbricoides/efeitos dos fármacos , Ascaris lumbricoides/isolamento & purificação , Criança , Pré-Escolar , Congo/epidemiologia , Filariose Linfática/epidemiologia , Feminino , Helmintíase/epidemiologia , Helmintíase/parasitologia , Infecções por Uncinaria/tratamento farmacológico , Infecções por Uncinaria/epidemiologia , Humanos , Masculino , Pessoa de Meia-Idade , Solo/parasitologia , Tricuríase/tratamento farmacológico , Tricuríase/epidemiologia , Trichuris/efeitos dos fármacos , Trichuris/isolamento & purificação , Wuchereria bancrofti/efeitos dos fármacos , Adulto Jovem
8.
AIDS Res Hum Retroviruses ; 19(12): 1163-6, 2003 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-14717118

RESUMO

L'Hoest's monkey's (Cercopithecus Ihoesti) are believed to be naturally infected with a simian immunodeficiency virus (SIV), termed SIVIho, but only a handful of isolates, all derived from captive animals from the Democratic Republic of Congo (DCR), have thus far been characterized. Here, we report the noninvasive detection and molecular characterization of SIVIho in a wild L'Hoest's monkey from the Nyungwe Forest in Rwanda. Screening four L'Hoest's monkey fecal samples collected opportunistically as part of a larger noninvasive survey of SIV prevalence in Nyungwe National Park we identified one to be vRNA positive. Reverse transcriptase polymerase chain reaction (RT-PCR) amplification of a subgenomic pol fragment (598 bp) identified a new SIVIho strain (RW30) that differed from previously reported SIVIho isolates in 17-22% of its nucleotide sequence. In a phylogenic tree of partial Pol protein sequences, RW30 fell well within the SIVIho radiation, but was not particularly closely related to any of the other strains. These results provide the first direct evidence that L'Hoewst's monkeys harbor SIVIho in the wild, that infection is prevalent in different areas of the species' habitat, and that geographically diverse SIVIho strains cluster in a single group according to their species of origin. L'Hoest's monkeys represent the third primate species for which the utility of noninvasive SIV testing has been documented.


Assuntos
Cercopithecus/virologia , Síndrome de Imunodeficiência Adquirida dos Símios/virologia , Vírus da Imunodeficiência Símia/isolamento & purificação , Animais , Animais Selvagens/virologia , Lentivirus/classificação , Lentivirus/genética , Filogenia , RNA Viral/análise , Síndrome de Imunodeficiência Adquirida dos Símios/diagnóstico , Vírus da Imunodeficiência Símia/classificação , Vírus da Imunodeficiência Símia/genética , Vírus da Imunodeficiência Símia/imunologia
9.
Parasit Vectors ; 7: 300, 2014 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-24984769

RESUMO

BACKGROUND: Little is known regarding risk factors for lymphatic filariasis (LF) in Central Africa. We studied the epidemiology of LF in an endemic village in the Republic of Congo. METHODS: Dependent variables were Wuchereria bancrofti antigenemia (ICT card test) and microfilaremia (night blood smears). The following factors were investigated: sex, age, bed net, latrines, source of water, uptake of anthelmintic drugs, hunting/fishing activities, and occasionally sleeping in the bush. Mixed multivariate logistic regression models were used. RESULTS: 134 of 774 subjects aged ≥ 5 years (17.3%) had W. bancrofti antigenemia and 41 (5.3%) had microfilaremia (mf). Infection rates increased with age up to roughly 20 years and remained stable thereafter. Multivariate analysis of antigenemia demonstrated an increased risk for males (OR = 2.0 [1.3-3.0]) and for people who hunt or fish (OR = 1.5 [1.0-2.4]) and a protective effect of latrines (OR = 0.5 [0.4-0.8]). Among males, those hunting or fishing at night had an increased risk for antigenemia (OR = 1.9 [1.1-3.5]), and use of latrines was protective (OR = 0.5 [0.3-0.9]). For females, bed nets were protective (OR = 0.4 [0.1-0.9]), and there was a strong household effect (intraclass correlation coefficient [ICC]: 0.24). When mf was used as the dependent variable, males had a higher risk for infection (OR = 5.4 [2.1-13.4]), latrines had a protective effect (OR = 0.4 [0.1-0.9]) and there was a marked household effect (ICC = 0.49). CONCLUSIONS: Age, sex, and occupation-dependent exposure to mosquitoes were important risk factors for infection with W. bancrofti in this study. It is likely that men often acquire infection in high transmission areas outside of the village, while children and women are infected in areas with lower transmission inside or near the village. Additional studies are needed to determine whether these findings apply to other areas in Central Africa.


Assuntos
Filariose Linfática/epidemiologia , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Anti-Helmínticos/uso terapêutico , Criança , Pré-Escolar , Congo/epidemiologia , Feminino , Humanos , Mosquiteiros Tratados com Inseticida , Masculino , Pessoa de Meia-Idade , Exposição Ocupacional , Razão de Chances , Prevalência , Fatores de Risco , Engenharia Sanitária , Abastecimento de Água , Adulto Jovem
10.
Am J Trop Med Hyg ; 89(5): 916-8, 2013 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-24019435

RESUMO

Abstract. The value of a semi-quantitative scoring of the filarial antigen test (Binax Now Filariasis card test, ICT) results was evaluated during a field survey in the Republic of Congo. One hundred and thirty-four (134) of 774 tests (17.3%) were clearly positive and were scored 1, 2, or 3; and 11 (1.4%) had questionable results. Wuchereria bancrofti microfilariae (mf) were detected in 41 of those 133 individuals with an ICT test score ≥ 1 who also had a night blood smear; none of the 11 individuals with questionable ICT results harbored night mf. Cuzick's test showed a significant trend for higher microfilarial densities in groups with higher ICT scores (P < 0.001). The ICT scores were also significantly correlated with blood mf counts. Because filarial antigen levels provide an indication of adult worm infection intensity, our results suggest that semi-quantitative reading of the ICT may be useful for grading the intensity of filarial infections in individuals and populations.


Assuntos
Antígenos de Helmintos/sangue , Filariose/diagnóstico , Microfilárias/isolamento & purificação , Wuchereria bancrofti/isolamento & purificação , Adolescente , Adulto , Idoso , Animais , Contagem de Células , Criança , Pré-Escolar , Congo/epidemiologia , Ensaio de Imunoadsorção Enzimática , Filariose/sangue , Filariose/epidemiologia , Filariose/parasitologia , Humanos , Microfilárias/imunologia , Pessoa de Meia-Idade , Kit de Reagentes para Diagnóstico , Projetos de Pesquisa , Wuchereria bancrofti/imunologia
11.
Am J Trop Med Hyg ; 89(1): 11-15, 2013 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-23690552

RESUMO

Global Program to Eliminate Lymphatic Filariasis (GPELF) guidelines call for using filarial antigen testing to identify endemic areas that require mass drug administration (MDA) and for post-MDA surveillance. We compared a new filarial antigen test (the Alere Filariasis Test Strip) with the reference BinaxNOW Filariasis card test that has been used by the GPELF for more than 10 years. Laboratory testing of 227 archived serum or plasma samples showed that the two tests had similar high rates of sensitivity and specificity and > 99% agreement. However, the test strip detected 26.5% more people with filarial antigenemia (124/503 versus 98/503) and had better test result stability than the card test in a field study conducted in a filariasis-endemic area in Liberia. Based on its increased sensitivity and other practical advantages, we believe that the test strip represents a major step forward that will be welcomed by the GPELF and the filariasis research community.


Assuntos
Antígenos de Helmintos/sangue , Filariose Linfática/diagnóstico , Wuchereria bancrofti , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Animais , Antígenos de Helmintos/imunologia , Criança , Cromatografia de Afinidade , Erradicação de Doenças/métodos , Filariose Linfática/sangue , Filariose Linfática/epidemiologia , Filariose Linfática/prevenção & controle , Feminino , Humanos , Libéria/epidemiologia , Masculino , Pessoa de Meia-Idade , Fitas Reagentes/normas , Sensibilidade e Especificidade , Wuchereria bancrofti/imunologia , Adulto Jovem
12.
Gynecol Oncol ; 92(3): 761-8, 2004 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-14984938

RESUMO

OBJECTIVE: To determine the temporal and spatial expression of interleukins (IL)-13 and IL-15 in ovarian carcinoma compared to normal ovarian tissue. METHODS: Quantitative RT-PCR, ELISA and immunohistochemistry. RESULTS: Q-RT-PCR, ELISA and immunohistochemical analysis indicates that IL-13 and IL-15 mRNA and protein are expressed in normal ovary at various phases of the menstrual cycle with immunoreactive proteins detected in granulosa/theca and luteal cells and to a lesser extent in stromal cells and surface epithelial cells. Compared to normal ovary, ovarian carcinoma expresses elevated levels of IL-13 and IL-15 mRNA, with higher IL-13 expression in primary vs. metastatic tumors. IL-13 and IL-15 protein expression was also higher in the tumor tissues compared to ascites. In normal ovary, ovarian tumors and ascites, the ratio of IL-13/IL-15 favored IL-13. Immunoreactive IL-13 and IL-15 proteins were localized primarily in the tumor cells and infiltrated inflammatory cells with increased intensity with disease stage. CONCLUSION: Normal ovary and ovarian tumors express IL-13 and IL-15 and pattern of their expression in carcinomas suggests that these cytokines may function in various ovarian cellular activities including inflammatory/immune responses that are integrated cellular events taking place in normal ovary and ovarian tumors.


Assuntos
Interleucina-13/biossíntese , Interleucina-15/biossíntese , Neoplasias Ovarianas/imunologia , Ovário/imunologia , Ascite/imunologia , Feminino , Humanos , Imuno-Histoquímica , Interleucina-13/genética , Interleucina-13/imunologia , Interleucina-15/genética , Interleucina-15/imunologia , Ciclo Menstrual/imunologia , Neoplasias Ovarianas/genética , Ovário/fisiologia , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa
13.
Environ Sci Technol ; 38(5): 1348-58, 2004 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-15046335

RESUMO

For the past 9 years, we experimentally flooded a wetland complex (peatland surrounding an open water pond) at the Experimental Lakes Area (ELA), northwestern Ontario, Canada, to examine the biogeochemical cycling of methyl mercury (MeHg) in reservoirs. Using input-output budgets, we found that prior to flooding, the wetland complex was a net source of approximately 1.7 mg MeHg ha(-1) yr(-1) to downstream ecosystems. In the first year of flooding, net yields of MeHg from the reservoir increased 40-fold to approximately 70 mg MeHg ha(-1) yr(-1). Subsequently, annual net yields of MeHg from the reservoir declined (10-50 mg MeHg ha(-1) yr(-1)) but have remained well above natural levels. The magnitude and timing of Hg methylation in the flooded peat portion of the wetland reservoir were very different than in the open water region of the reservoir. In terms of magnitude, net Hg methylation rates in the peat in the first 2 years of flooding were 2700 mg ha(-1) yr(-1), constituting over 97% of the MeHg produced at the whole-ecosystem level. But in the following 3 years, there was a large decrease in the mass of MeHg in the flooded peat due to microbial demethylation. In contrast, concentrations of MeHg in the open water region and in zooplankton, and body burdens of Hg in cyprinid fish, remained high for the full 9 years of this study. Microbial activity in the open water region also remained high, as evidenced by continued high concentrations of dissolved CO2 and CH4. Thus, the large short-term accumulation of MeHg mass in the peat appeared to have only a small influence on concentrations of MeHg in the biota; rather MeHg accumulation in biota was sustained by the comparatively small ongoing net methylation of Hg in the flooded pond where microbial activity remained high. In large reservoirs, where the effects of wind and fetch are greater than in the small experimental reservoir we constructed, differences can occur in the timing and extent of peat and soil erosion, effecting either transport of MeHg to the food chain or the fueling of microbial activity in open water sediments, both of which could have important long-term implications for MeHg concentrations in predatory fish.


Assuntos
Desastres , Mercúrio/química , Mercúrio/metabolismo , Poluentes da Água/análise , Poluentes da Água/metabolismo , Abastecimento de Água , Ecossistema , Cadeia Alimentar , Sedimentos Geológicos/química , Metilação , Solo , Microbiologia da Água , Movimentos da Água
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