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1.
Ecotoxicol Environ Saf ; 203: 111016, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32888590

RESUMO

Selenium (Se) is considered a beneficial element to higher plants based on its regulation of antioxidative system under abiotic or biotic stresses. However, the limit of beneficial and toxic physiological effects of Se is very narrow. In the present study, the antioxidant performance, nutritional composition, long-distance transport of Se, photosynthetic pigments, and growth of Coffea arabica genotypes in response to Se concentration in solution were evaluated. Five Coffea arabica genotypes (Obatã, IPR99, IAC125, IPR100 and Catucaí) were used, which were grown in the absence and presence of Se (0 and 1.0 mmol L-1) in nutrient solution. The application of 1 mmol L-1 Se promoted root browning in all genotypes. There were no visual symptoms of leaf toxicity, but there was a reduction in the concentration of phosphorus and sulfur in the shoots of plants exposed to high Se concentration. Except for genotype Obatã, the coffee seedlings presented strategies for regulating Se uptake by reducing long-distance transport of Se from roots to shoots. The concentrations of total chlorophyll, total pheophytin, and carotenoids were negatively affected in genotypes Obatã, IPR99, and IAC125 upon exposure to Se at 1 mmol L-1. H2O2 production was reduced in genotypes IPR99, IPR100, and IAC125 upon exposure to Se, resulting in lower activity of superoxide dismutase (SOD), and catalase (CAT). These results suggest that antioxidant metabolism was effective in regulating oxidative stress in plants treated with Se. The increase in sucrose, and decrease in SOD, CAT and ascorbate peroxidase (APX) activities, as well as Se compartmentalization in the roots, were the main biochemical and physiological modulatory effects of coffee seedlings under stress conditions due to excess of Se.


Assuntos
Antioxidantes/metabolismo , Coffea/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Selênio/farmacologia , Coffea/genética , Coffea/metabolismo , Coffea/fisiologia , Genótipo , Oxirredução , Fotossíntese/efeitos dos fármacos , Raízes de Plantas/efeitos dos fármacos , Raízes de Plantas/genética , Raízes de Plantas/metabolismo , Plântula/efeitos dos fármacos , Plântula/genética , Plântula/metabolismo , Plântula/fisiologia , Selênio/análise , Selênio/metabolismo , Especificidade da Espécie
2.
Ecotoxicol Environ Saf ; 205: 111372, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32977281

RESUMO

The production of natural selenium (Se)-rich food by using a high-Se crop cultivar is beneficial to human health and environmental safety; however, the underlying mechanism of different Se-accumulation ability between high- and low-Se rice cultivars remains unclear. A low-grain-Se cultivar and high-grain-Se cultivar of rice were used as test materials, and two levels of Se (0 and 0.5 mg kg-1) were arranged in a randomized design containing twelve replicates. The dynamic changes of shoot Se concentration and accumulation, xylem sap Se concentration, shoot and grain Se distribution, Se transporters genes (OsPT2, Sultr1;2, NRT1.1B) expression of the high- and low-Se rice cultivars were determined. The shoot Se concentration and accumulation of the high-Se rice showed a greater degree of reduction than those of the low-Se rice during grain filling stage, indicating that leaves of high-Se rice served as a Se source and supplied more Se for the growth centre grain. The expression levels of OsPT2, NRT1.1B and Sultr1;2 in the high-Se rice cultivar were significantly higher than those in the low-Se rice cultivar, which indicated that the high-Se rice cultivar possessed better transport carriers. The distribution of Se in grain of the high-Se rice cultivar was more uniform, whereas the low-Se cultivar tended to accumulate Se in embryo end. The stronger reutilization of Se from shoots to grains promoted by increased transporters genes expression and optimized grain storage space may explain how the high-Se rice cultivar is able to accumulate more Se in grain.


Assuntos
Oryza/fisiologia , Selênio/metabolismo , Cádmio/metabolismo , Grão Comestível/química , Humanos , Oryza/metabolismo , Poluentes do Solo/análise , Xilema/metabolismo
3.
Ecotoxicol Environ Saf ; 204: 111045, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32745785

RESUMO

Cardamine violifolia (Brassicaceae) is a novel selenium(Se) hyperaccumulation plant with rich nutrients, and serves as a good source of special vegetables in Enshi, China. The present study aimed to investigate the effects of the application of selenate, selenite, and Se yeast (50-800 mg/L) on the growth, Se accumulation, nutrient uptake, and antioxidant response of C. violifolia. The results showed that the Se accumulation efficiency was selenate > selenite > Se yeast, the maximum Se concentration could achieve over 7000 mg/kg, and about 90% was organic Se. The major Se speciation found was mainly SeCys2 and the proportion of various Se species were affected by the Se forms and concentrations. Besides, the plant growth, nutrition quality indexes, element uptakes, and antioxidant responses indicated that 200 mg/L selenate was optimum for C. violifolia to accumulate Se without much impacts, while to obtain more proportion of organic Se, 200 mg/L selenite might be a better choice.


Assuntos
Antioxidantes/metabolismo , Cardamine/fisiologia , Ácido Selênico/metabolismo , Ácido Selenioso/metabolismo , Selênio/metabolismo , Fermento Seco/química , Bioacumulação , Cardamine/química , Cardamine/enzimologia , Cardamine/crescimento & desenvolvimento , China , Relação Dose-Resposta a Droga , Elementos , Fenômenos Fisiológicos da Nutrição , Valor Nutritivo
4.
Huan Jing Ke Xue ; 41(2): 962-969, 2020 Feb 08.
Artigo em Chinês | MEDLINE | ID: mdl-32608758

RESUMO

Cadmium (Cd) is a highly toxic heavy metal. Brassica rapa (pak choi) is a vastly common vegetable, which readily accumulates Cd. Given the current conditions of Cd contamination in domestic soil, it is important to reduce Cd accumulation in the edible part of pak choi. Research has shown that selenium (Se) can regulate Cd uptake by plants. Cd accumulation (three cultivars) and Cd uptake kinetics in pak choi were investigated under hydroponic conditions. Results showed that the three levels of selenite significantly reduced Cd content in the Hangzhouyoudonger shoot by 50%, while the levels in Suzhouqinggen and Shanghaiqing shoots were not significantly decreased with elevated levels of selenite. Selenite reduces the Cd translocation factors, and higher levels had more obvious effects; 50 µmol·L-1 of selenite significantly decreased the factors by 50% in Hangzhouyoudonger and Suzhouqinggen shoots. Selenite also increased iron (Fe) and manganese (Mn) contents in pak choi, especially in the Hangzhouyoudonger shoot, where 50 µmol·L-1 increased the Fe content by approximately 50%. In the uptake kinetics of Cd, both selenite and selenate significantly increased Cd uptake rates and Vmax by over 100%. Therefore, Se could reduce Cd accumulation in pak choi. This also depended on the tested cultivar. Therefore, reduction effects of Se on the Cd content mainly stemmed from the alteration of Cd translocation in pak choi instead of the uptake competition between Cd and Se.


Assuntos
Brassica rapa/metabolismo , Cádmio/metabolismo , Brotos de Planta/metabolismo , Selênio/metabolismo , Poluentes do Solo/metabolismo , Ácido Selênico , Ácido Selenioso
5.
Ecotoxicol Environ Saf ; 203: 111008, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32678766

RESUMO

Glutathione peroxidases (Gpxs) play vital roles in elimination of hydroperoxide and other reactive oxygen species through catalyzing reduced glutathione to protect from oxidative stress caused by heavy metals such as lead. Among the family of Gpxs, Gpx3 is the only extracellular enzyme synthesized in the kidney and actively secreted into the plasma. This study investigated mechanisms of lead-induced GPx3 inactivation both at the animal and molecular levels. Six-week-old mice were randomly divided into 4 groups, and exposed to different lead concentrations (0, 1, 2 and 4 g/L) in their drinking water for 4 weeks. Contents of GPx3 in blood serum were tested by enzyme-linked immunosorbent assay (ELISA) and the mRNA levels of Gpx3 in mice nephrocytes were determined by quantitative real-time PCR (qPCR), both of which showed significantly inhibited at higher lead concentrations accompanied by the decreased Gpx3 activities and the elevated levels of malondialdehyde (MDA) in nephrocytes, which indicated that lead could induce strongly oxidative stress through affecting Gpx3 function. So we further investigated molecular mechanisms of GPx3 inactivation caused by lead with multiple spectroscopic techniques, isothermal titration calorimetry (ITC) and molecular docking studies in vitro. Results showed that lead statically quenched GPx3 fluorescence by tightly binding to the structural domain of GPx3 in a 3:1 ratio with high binding affinity (K = 3.1(±0.087) × 107 mol-1). Further investigation of the conformation of GPx3 by UV-visible spectroscopy and circular dichroism (CD) spectroscopy indicated that lead changed the secondary structure of GPx3 by loosening the GPx3 skeleton and decreasing the hydrophobicity around tryptophan residues. This work proved in vivo and in vitro experiments that lead could induce oxidative stress in mice nephrocytes by interacting with GPx3.


Assuntos
Glutationa Peroxidase/metabolismo , Rim/efeitos dos fármacos , Chumbo/toxicidade , Poluentes da Água/toxicidade , Animais , Glutationa Peroxidase/química , Rim/metabolismo , Rim/patologia , Chumbo/metabolismo , Camundongos , Estresse Oxidativo/efeitos dos fármacos , Ligação Proteica , Estrutura Secundária de Proteína , Selênio/metabolismo , Poluentes da Água/metabolismo
7.
Chem Biol Interact ; 327: 109162, 2020 Aug 25.
Artigo em Inglês | MEDLINE | ID: mdl-32524993

RESUMO

Hundreds of millions of people worldwide are exposed to unacceptable levels of carcinogenic inorganic arsenic. Animal models have shown that selenium and arsenic are mutually protective through the formation and elimination of the seleno-bis(S-glutathionyl) arsinium ion [(GS)2AsSe]-. Consistent with this, human selenium deficiency in arsenic-endemic regions is associated with arsenic-induced disease, leading to the initiation of human selenium supplementation trials. In contrast to the protective effect observed in vivo, in vitro studies have suggested that selenite increases arsenite cellular retention and toxicity. This difference might be explained by the rapid conversion of selenite to selenide in vivo. In the current study, selenite did not protect the human hepatoma (HepG2) cell line against the toxicity of arsenite at equimolar concentrations, however selenide increased the IC50 by 2.3-fold. Cytotoxicity assays of arsenite + selenite and arsenite + selenide at different molar ratios revealed higher overall mutual antagonism of arsenite + selenide toxicity than arsenite + selenite. Despite this protective effect, in comparison to 75Se-selenite, HepG2 cells in suspension were at least 3-fold more efficient at accumulating selenium from reduced 75Se-selenide, and its accumulation was further increased by arsenite. X-ray fluorescence imaging of HepG2 cells also showed that arsenic accumulation, in the presence of selenide, was higher than in the presence of selenite. These results are consistent with a greater intracellular availability of selenide relative to selenite for protection against arsenite, and the formation and retention of a less toxic product, possibly [(GS)2AsSe]-.


Assuntos
Arsenitos/toxicidade , Substâncias Protetoras/farmacologia , Ácido Selenioso/farmacologia , Compostos de Selênio/farmacologia , Arsênico/metabolismo , Arsenitos/metabolismo , Células Hep G2 , Humanos , Inativação Metabólica/efeitos dos fármacos , Substâncias Protetoras/metabolismo , Radioisótopos/metabolismo , Ácido Selenioso/metabolismo , Selênio/metabolismo , Compostos de Selênio/metabolismo , Radioisótopos de Selênio/metabolismo
8.
Ecotoxicol Environ Saf ; 201: 110777, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32485493

RESUMO

Selenium (Se) is a beneficial element to higher plants. Application of Se at low concentrations enhances the antioxidant metabolism reducing the reactive oxygen species (ROS) generated by plant membrane cells. This study aimed to evaluate how the application of Se in the forms sodium selenate and sodium selenite regulates ROS scavenging in field-grown cowpea plants. Seven Se application rates (0; 2.5; 5; 10; 20; 40 and 60 g ha-1) of each of the two Se forms were applied to plants via the soil. Photosynthetic pigments concentration, gas exchange parameters, lipid peroxidation by malondialdehyde (MDA) concentration, hydrogen peroxide concentration, activity of catalase (CAT, EC:1.11.1.6), glutathione reductase (GR, EC:1.6.4.2), ascorbate peroxidase (APX, EC:1.11.1.11) and Se concentration in leaves and grains were evaluated. In general, Se application led to a decrease in chlorophyll a concentration whilst leading to an increase in chlorophyll b, indicating conservation of total chlorophyll concentration. Application of 2.5 g ha-1 of Se as selenate provided a notable increase in total chlorophyll and total carotenoids compared to the other application rates. Selenate and selenite application decreased lipid peroxidation. However, each Se source acted in a different pathway to combat ROS. While selenate showed more potential to increase activity of APX and GR, selenite showed a higher potential to increase CAT activity. The negative correlation between CAT and GR is indicative that both pathways might be activated under distinct circumstances. The more prominent activity of CAT under high rates of selenite resulted in a negative correlation of this enzyme with chlorophyll a and carotenoids. Both selenate and selenite application increased sucrose and total sugars concentration in leaves of cowpea plants. Overall, these results indicate that application of Se in cowpea under field conditions stimulates distinct pathways to scavenge ROS. This could prove beneficial to mitigate oxidative stress during plant development.


Assuntos
Espécies Reativas de Oxigênio/metabolismo , Ácido Selênico/toxicidade , Ácido Selenioso/toxicidade , Vigna/efeitos dos fármacos , Antioxidantes/metabolismo , Ascorbato Peroxidases/metabolismo , Catalase/metabolismo , Clorofila , Clorofila A , Glutationa Redutase/metabolismo , Fotossíntese , Folhas de Planta/metabolismo , Ácido Selênico/metabolismo , Ácido Selenioso/metabolismo , Selênio/metabolismo , Selenito de Sódio , Vigna/metabolismo , Vigna/fisiologia
9.
Chemosphere ; 258: 127341, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32563067

RESUMO

Cadmium (Cd) is a primary environmental pollutant which causes the immune dysfunction of aquatic animals. MicroRNAs (miRNAs) play a key role in programmed necrosis and apoptosis of immune organs. Selenium (Se), known as an important element, can antagonize Cd toxicity in birds, but the impact of Se on common carps (Cyprinus carpio) has not been reported. To investigate the Cd-induced immunotoxicity mechanism mediated by miR-216a in splenic lymphocytes of common carp and antagonized by Se, we extracted lymphocytes from the spleen and divided them into control group, Se group (10-6 mol/L of Na2SeO3), Se + Cd group and Cd group (4 × 10-5 mol/L of CdCl2). After 6 h of incubation, AO/EB staining, Flow cytometry, qPCR and Western blot were performed. The results showed that Cd exposure caused the apoptosis (BAX, Bcl-2, Caspase 3, Caspase 9) and programmed necrosis (RIP, RIP3, MLKL) in lymphocytes, increased the expression of CYP enzymes, glycometabolism-related enzymes and production of ROS, while irritated the oxidative stress (MDA, SOD, CAT and GSH-PX), upregulated the expression of miR-216a which attenuated the levels of PI3K. However, those variations were apparently mitigated in the Se + Cd group. In short, we have proven that Cd activates oxidative stress and miR-216a-PI3K/AKT axis disorder, thus promoting apoptosis and necrosis in lymphocytes. Moreover, Se can antagonize Cd-triggered apoptosis and necrosis in lymphocytes.


Assuntos
Apoptose/efeitos dos fármacos , Cádmio/toxicidade , Carpas/metabolismo , Linfócitos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Selênio/farmacologia , Animais , MicroRNAs/metabolismo , Necrose/induzido quimicamente , Fosfatidilinositol 3-Quinases/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , Selênio/metabolismo , Baço/citologia
10.
Proc Natl Acad Sci U S A ; 117(20): 10789-10796, 2020 05 19.
Artigo em Inglês | MEDLINE | ID: mdl-32358195

RESUMO

Oxidation of cysteine thiols by physiological reactive oxygen species (ROS) initiates thermogenesis in brown and beige adipose tissues. Cellular selenocysteines, where sulfur is replaced with selenium, exhibit enhanced reactivity with ROS. Despite their critical roles in physiology, methods for broad and direct detection of proteogenic selenocysteines are limited. Here we developed a mass spectrometric method to interrogate incorporation of selenium into proteins. Unexpectedly, this approach revealed facultative incorporation of selenium as selenocysteine or selenomethionine into proteins that lack canonical encoding for selenocysteine. Selenium was selectively incorporated into regulatory sites on key metabolic proteins, including as selenocysteine-replacing cysteine at position 253 in uncoupling protein 1 (UCP1). This facultative utilization of selenium was initiated by increasing cellular levels of organic, but not inorganic, forms of selenium. Remarkably, dietary selenium supplementation elevated facultative incorporation into UCP1, elevated energy expenditure through thermogenic adipose tissue, and protected against obesity. Together, these findings reveal the existence of facultative protein selenation, which correlates with impacts on thermogenic adipocyte function and presumably other biological processes as well.


Assuntos
Tecido Adiposo/metabolismo , Cisteína/metabolismo , Obesidade/metabolismo , Selênio/metabolismo , Termogênese , Proteína Desacopladora 1/metabolismo , Tecido Adiposo/fisiologia , Animais , Células Cultivadas , Masculino , Espectrometria de Massas/métodos , Camundongos , Camundongos Endogâmicos C57BL , Espécies Reativas de Oxigênio/metabolismo
11.
PLoS One ; 15(5): e0232160, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32379770

RESUMO

There is interest in supplementing animals and humans with selenium (Se) above Se-adequate levels, but the only good biomarker for toxicity is tissue Se. We targeted liver because turkeys fed 5 µg Se/g have hepatic Se concentrations 6-fold above Se-adequate (0.4 µg Se/g) levels without effects on growth or health. Our objectives were (i) to identify transcript biomarkers for high Se status, which in turn would (ii) suggest proteins and pathways used by animals to adapt to high Se. Turkey poults were fed 0, 0.025, 0.4, 0.75 and 1.0 µg Se/g diet in experiment 1, and fed 0.4, 2.0 and 5.0 µg Se/g in experiment 2, as selenite, and the full liver transcriptome determined by RNA-Seq. The major effect of Se-deficiency was to down-regulate expression of a subset of selenoprotein transcripts, with little significant effect on general transcript expression. In response to high Se intake (2 and 5 µg Se/g) relative to Se-adequate turkeys, there were only a limited number of significant differentially expressed transcripts, all with only relatively small fold-changes. No transcript showed a consistent pattern of altered expression in response to high Se intakes across the 1, 2 and 5 µg Se/g treatments, and there were no associated metabolic pathways and biological functions that were significant and consistently found with high Se supplementation. Gene set enrichment analysis also found no gene sets that were consistently altered by high-Se and supernutritional-Se. A comparison of differentially expressed transcript sets with high Se transcript sets identified in mice provided high Se (~3 µg Se/g) also failed to identify common differentially expressed transcript sets between these two species. Collectively, this study indicates that turkeys do not alter gene expression in the liver as a homeostatic mechanism to adapt to high Se.


Assuntos
Selênio/metabolismo , Transcriptoma/efeitos dos fármacos , Perus/metabolismo , Animais , Biomarcadores/metabolismo , Dieta , Suplementos Nutricionais/toxicidade , Glutationa Peroxidase/metabolismo , Fígado/efeitos dos fármacos , Fígado/metabolismo , Masculino , Estado Nutricional , RNA Mensageiro/genética , Selenocisteína/genética , Selenoproteínas/genética , Selenoproteínas/metabolismo , Transcriptoma/genética , Perus/genética
12.
Chemosphere ; 255: 126941, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32388259

RESUMO

With the aim of evaluating health risk to hake consumers, mercury and selenium were measured in muscle, liver, gonads, kidney, and gills of 62 specimens of Merluccius productus from northern Gulf of California. Means ± confidence interval (95% confidence level) concentrations (mg kg-1 wet weight) of Hg in tissues were: gonads (1.01 ± 0.25) > muscle (0.44 ± 0.06) > gills (0.29 ± 0.04) > kidneys (0.20 ± 0.07) > liver (0.02 ± 0.004). No significant differences between sexes were found for Hg. The distribution of mean concentrations of Se (mg kg-1 wet weight) were: kidneys (4.61 ± 1.27) > liver (1.66 ± 0.22) > gonads (1.66 ± 0.75) > gills (0.86 ± 0.04) > muscle (0.40 ± 0.09). Se in gonads showed a significant difference between sex (females > males). Positive significant correlations with total length (p < 0.05) and total weight (p < 0.05) were found in the same tissue for both morphological variables: Hg in muscle, Se in muscle and Se in liver. An excess of Se over Hg (molar ratio Se:Hg > 1) was found in all tissues. The Hazard Quotient health risk index was evaluated for humans that consume muscle and gonads. The recommended Hg safe intake for adults and children were 110.0 and 33.0 g week-1, respectively for muscle; for gonads weekly consumption portions of 35.0 and 14.0 g for adults and children represent no Hg risk. There was no risk of exposure to Se.


Assuntos
Monitoramento Ambiental , Gadiformes/metabolismo , Mercúrio/metabolismo , Selênio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Bioacumulação , California , Criança , Exposição Dietética/estatística & dados numéricos , Feminino , Peixes , Gônadas , Humanos , Masculino , Mercúrio/análise , Músculos/metabolismo , Perciformes , Medição de Risco , Selênio/análise , Poluentes Químicos da Água/análise
13.
Biomed Environ Sci ; 33(4): 260-268, 2020 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-32438963

RESUMO

Objective: To explore the association between soil selenium levels and the risk of diabetes in Chinese adults aged 35-74 years. Methods: Data for this study were derived from the China Chronic Diseases and Behavioral Risk Factors Surveillance 2010 survey. Selenium concentrations in soil were obtained from the Atlas of Soil Environmental Background Values in China. A two-level binary logistic regression model was used to determine the association between soil selenium concentrations and the risk of diabetes, with participants nested within districts/counties. Results: A total of 69,332 participants aged 35-74 years, from 158 districts/counties were included in the analysis. Concentrations of selenium in soil varied greatly across the 158 districts/counties, with a median concentration of 0.219 mg/kg ( IQR: 0.185-0.248). The results showed that both Quartile 1 (0.119-0.185 mg/kg) and Quartile 4 (0.249-0.344 mg/kg) groups were positively associated with diabetes compared to a soil selenium concentration of 0.186-0.219 mg/kg (Quartile 2), crude odds ratios ( ORs) (95% CI) were 1.227 (1.003-1.502) and 1.280 (1.048-1.563). The P values were 0.045 and 0.013, for Quartile 1 and Quartile 4 groups, respectively. After adjusting for all confounding factors of interest, the Quartile 1 group became non-significant, and the Quartile 4 group had an adjusted OR (95% CI) of 1.203 (1.018-1.421) relative to the reference group (Quartile 2), the P values was 0.030. No significant results were seen for the Quartile 3 group (0.220-0.248 mg/kg) compared to the reference group. Conclusion: Excessive selenium concentrations in soil could increase the risk of diabetes among Chinese adults aged 35-74 years.


Assuntos
Diabetes Mellitus/epidemiologia , Selênio/metabolismo , Solo/química , Adulto , Idoso , China/epidemiologia , Diabetes Mellitus/induzido quimicamente , Dieta , Feminino , Humanos , Modelos Logísticos , Masculino , Pessoa de Meia-Idade , Razão de Chances , Fatores de Risco , Selênio/deficiência
14.
Bull Environ Contam Toxicol ; 104(5): 595-601, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32242255

RESUMO

Total mercury (THg) and selenium (TSe) levels were measured in stomach contents (SC) and twelve tissues of cutthroat trout (Oncorhynchus clarkii) occurring in three high-elevation lakes of Colorado, USA, inhabiting watersheds absent past and current mining activities. For 32 of 36 tissues, including muscle, mean THg wet weight (ww) concentrations were greater than in the diet (SC) for all sites, indicating biomagnification. Ranges of THg (µg/kg ww) for SC and stomach tissue (ST) were 1.23-73.54 and 14.55-61.35, respectively. Selenium concentrations in fish muscle were not greater than in the SC indicating a trophic transfer factor < 1.0. However, in several other tissues, mean Se dry weight (dw) levels were greater than in SC for all three lakes. Ranges of TSe for SC and ST were 166-7544 and 797-7523 (µg/kg dw), respectively. The muscle to egg/ovary ratio for Se averaged 2.30, 4.60, and 2.68 for the three populations. The variability of SC (planktonic vs. benthic) and differential distributions of THg and TSe in SC and organ-tissues generated questions focusing on the seasonal, physiological, and genetic drivers of these organometal(loid)s in subalpine trout.


Assuntos
Bioacumulação , Monitoramento Ambiental/métodos , Conteúdo Gastrointestinal/química , Mercúrio/metabolismo , Oncorhynchus/metabolismo , Selênio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Colorado , Cadeia Alimentar , Lagos/química , Mercúrio/análise , Mineração , Plâncton/química , Selênio/análise , Poluentes Químicos da Água/análise
15.
Artigo em Inglês | MEDLINE | ID: mdl-32297060

RESUMO

Experiments examining mercury (Hg) toxicity in Daphnia are usually conducted in highly standardized conditions that prevent the formation of biofilm. Although such standardization has many advantages, extrapolation of results to natural conditions and inference of ecological effects is challenging. This is especially true since biofilms can accumulate metals/metalloids and play a key role in their transfer to higher trophic level organisms. In this study, we experimentally tested the effects of spontaneously appearing biofilm in Daphnia cultures on accumulation of Hg and its natural antagonist selenium (Se) in Daphnia magna. We added Hg (in the form of mercury (II) chloride) at two concentrations (0.2 µg/L and 2 µg/L) to experimental microcosms and measured the uptake of Hg and Se by D. magna in the presence and absence of biofilm. To test for consistent and replicable results, we ran two identical experimental sets one week apart. Biofilm presence significantly reduced the accumulation of Hg, while increasing the tissue Se content in D. magna, and these findings were reproducible across experimental sets. These findings indicate that highly standardized tests may not be adequate to predict the bioaccumulation and potential toxicity of metals/metalloids under natural conditions.


Assuntos
Biofilmes/efeitos dos fármacos , Daphnia/metabolismo , Mercúrio/metabolismo , Selênio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Biofilmes/crescimento & desenvolvimento
16.
Artigo em Inglês | MEDLINE | ID: mdl-32333252

RESUMO

Cadmium (Cd) is probably the most damaging metal to plant species; with a long biological half-life, it can be taken up by plants, disrupting the cell homeostasis and triggering several metabolic pathways. Selenium (Se) improves plant defence systems against stressful conditions, but the biochemical antioxidant responses to Cd stress in tomato plants is poorly understood. To further address the relationship of Cd-stress responses with Se mineral uptake, Cd and Se concentration, proline content, MDA and H2O2 production, and the activity of SOD, APX, CAT and GR enzymes were analyzed in Micro-Tom (MT) plants submitted to 0.5 mM Cd. The results revealed different responses according to Se combination and Cd application. For instance, roots and leaves of MT plants treated with Se exhibited an increase in dry mass and nutritional status, exhibited lower proline content and higher APX and GR activities when compared with plants with no Se application. Plants submitted to 0.5 mM Cd, irrespective of Se exposure, exhibited lower proline, MDA and H2O2 content and higher SOD, CAT and GR activities. Selenium may improve tolerance against Cd, which allowed MT plants exhibited less oxidative damage to the cell, even under elevated Cd accumulation in their tissues. The results suggest that Se application is an efficient management technique to alleviate the deleterious effects of Cd-stress, enhancing the nutritional value and activity of ROS-scavenging enzymes in tomato plants.


Assuntos
Cádmio/toxicidade , Lycopersicon esculentum/fisiologia , Estresse Oxidativo/fisiologia , Selênio/metabolismo , Poluentes do Solo/toxicidade , Antioxidantes , Glutationa , Peróxido de Hidrogênio , Oxirredução , Folhas de Planta , Raízes de Plantas
17.
Chemosphere ; 251: 126347, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32169700

RESUMO

Currently, exploring effective measures to reduce multiple toxic metals accumulation in rice grains is an urgent issue to be tackled. Pot experiments were thus conducted to explore the effects and mechanisms of foliar spraying with composite sols of silicon (Si) and selenium (Se) during tillering to booting stage on diminishing cadmium (Cd) and lead (Pb) translocation to rice grains and affiliated physiological and biochemical responses in rice seedlings grown in Cd + Pb-polluted soils (positive control). Results showed that Cd and Pb contents in leaves or grains were distinctly below the positive control by the sols. Compared to the positive control, transcriptions of Cd transporter-related genes including OsLCT1, OsCCX2, OsHMA2 and OsPCR1 genes in leaves, and OsLCT1, OsCCX2, TaCNR2 and OSPCR1 in peduncles were downregulated by the increasing sols. Meanwhile, Se-binding protein 1 was evidently upregulated, together to retard Cd and Pb translocation to rice grains. The sols not only upregulated transcriptions of Lhcb1, RbcL, and OsBTF3 genes and production of psbA, Lhcb1 and RbcL proteins, but also increased the chlorophylls contents and RuBP carboxylase activities in the leaves, improving photosynthesis. The sols restrained ROS production from NADPH oxidases, but activated glutathione peroxidase, alleviating oxidative stress and damage. Additionally, Se was significantly enriched and was existed as selenomethionine in the rice grains. However, Pb transporter-related genes remain to be specified. Thus, the composite sols have potential to reduce Cd and Pb accumulation, mitigate oxidative damage, and promote photosynthesis and organic Se enrichment in rice plants under Cd and Pb combined pollution.


Assuntos
Cádmio/toxicidade , Chumbo/toxicidade , Oryza/fisiologia , Poluentes do Solo/toxicidade , Antioxidantes/metabolismo , Cádmio/análise , Clorofila/metabolismo , Poluição Ambiental , Chumbo/análise , Oryza/química , Estresse Oxidativo/efeitos dos fármacos , Fotossíntese , Folhas de Planta/metabolismo , Plântula/efeitos dos fármacos , Selênio/química , Selênio/metabolismo , Silício/química , Silício/metabolismo , Solo/química , Poluentes do Solo/análise
18.
Food Chem ; 319: 126537, 2020 Jul 30.
Artigo em Inglês | MEDLINE | ID: mdl-32193059

RESUMO

Since selenium (Se) is an essential mineral, animals must be able to metabolize the various selenocompounds in meat, fish and vegetables. It is unclear how animals, including humans, utilize selenocompound efficiently, but we hypothesized that gut microflora might contribute to these processes. In this study, we revealed that Se-methylselenocysteine and selenocyanate were metabolized to selenomethionine (SeMet) by intestinal microflora, suggesting selenocompounds might be metabolized to SeMet, which can be used by the host organism. The major urinary selenosugar, 1ß-methylseleno-N-acetyl-d-galactosamine, was utilized less in microflora-suppressed than healthy rats, suggesting that this sugar can be transformed to a nutritionally available form by gut microflora in animals with a healthy microbiota. We concluded that, in rats at least, gut microflora has a role in the metabolism of Se in the host animal, and this finding might be worth investigating in humans.


Assuntos
Microbioma Gastrointestinal , Selênio/metabolismo , Animais , Cianatos/metabolismo , Masculino , Valor Nutritivo , Ratos , Ratos Wistar , Compostos de Selênio/metabolismo , Selenocisteína/análogos & derivados , Selenocisteína/metabolismo , Selenometionina/metabolismo
19.
Poult Sci ; 99(3): 1491-1501, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32111317

RESUMO

This study investigated the influence of an organic mineral-supplemented broiler diet on the quality of nuggets. The resulting chicken nuggets were enriched with inorganic and organic forms of Zn and Se. The nuggets were processed by incorporating extracts from food industry by-products (rosemary [RH and RL], hydroxytyrosol [HYT], pomegranate [P], grape [GS], and Harpagophytum [H]). The physiochemical, microbiological, and sensory characteristics of the chicken nuggets were evaluated over a 12-month period of frozen storage. The addition of natural extracts did not affect the pH, proximate composition, or color (CIELab) of the nuggets among samples. However, significative differences were found between month of analysis (range from pH 6.16 to 6.63; luminosity from 62.51 to 84.74; redness from 0.16 to 7.14; and yellowness from 10.80 to 33.77). In addition, the combination of phenolic compounds with Zn and Se retarded microbial growth and reduced protein and lipid oxidation, thus maintaining the sensory quality and extending the shelf life of this product. For instance, the combination of RL + GS reduced in 75% the microbiological growth regarding the control sample (C), while samples that incorporated RH + P or HYT + P + H presented 50% less than C. In addition, upon only incorporating organic minerals Zn and Se, microbiological deterioration is reduced in 15%. This mix was significantly effective at reducing the oxidative reactions of lipids and proteins by 40% and 50%, as measured after 9 and 12 mo of frozen storage, respectively. The addition of the natural extracts and Zn and Se did not adversely affect the acceptability of the meat product.


Assuntos
Armazenamento de Alimentos , Alimentos Congelados/análise , Carne/análise , Minerais/metabolismo , Valor Nutritivo , Extratos Vegetais/metabolismo , Ração Animal/análise , Animais , Galinhas , Dieta/veterinária , Suplementos Nutricionais/análise , Relação Dose-Resposta a Droga , Alimentos Congelados/microbiologia , Carne/microbiologia , Minerais/administração & dosagem , Extratos Vegetais/administração & dosagem , Distribuição Aleatória , Selênio/administração & dosagem , Selênio/metabolismo , Zinco/administração & dosagem , Zinco/metabolismo
20.
Biol Pharm Bull ; 43(3): 366-374, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115498

RESUMO

Selenoprotein P (SeP) is one of the 25 human selenocysteine (Sec)-containing proteins, and is generally thought to function as a plasma carrier of the trace element selenium in the body. Recent studies, however, indicate unsuspected pivotal roles of SeP in human diseases, particularly in type 2 diabetes mellitus (T2DM) and pulmonary arterial hypertension (PAH). In this review, we will summarize the characteristics of SeP and recent advances in the field, especially focusing on the emerging roles of SeP in pathophysiological conditions. We will also discuss potential medical/pharmaceutical applications targeting SeP.


Assuntos
Selenoproteína P/sangue , Selenoproteína P/fisiologia , Animais , Biomarcadores , Diabetes Mellitus Tipo 2/fisiopatologia , Humanos , Plasma , Prognóstico , Hipertensão Arterial Pulmonar/fisiopatologia , Selênio/metabolismo , Selenoproteína P/efeitos dos fármacos
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