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1.
Brain Sci ; 10(7)2020 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-32709155

RESUMO

The essential trace metals iron, zinc, and copper have a significant physiological role in healthy brain development and function. Especially zinc is important for neurogenesis, synaptogenesis, synaptic transmission and plasticity, and neurite outgrowth. Given the key role of trace metals in many cellular processes, it is important to maintain adequate levels in the brain. However, the physiological concentration of trace metals, and in particular zinc, in the human and animal brain is not well described so far. For example, little is known about the trace metal content of the brain of animals outside the class of mammals. Here, we report the concentration of iron, zinc, and copper in fresh brain tissue of different model-species of the phyla Chordata (vertebrates (mammals, fish)), Annelida, Arthropoda (insects), and Mollusca (snails), using inductively coupled plasma mass-spectrometry (ICP-MS). Our results show that the trace metals are present in the nervous system of all species and that significant differences can be detected between species of different phyla. We further show that a region-specific distribution of metals within the nervous system already exists in earthworms, hinting at a tightly controlled metal distribution. In line with this, the trace metal content of the brain of different species does not simply correlate with brain size. We conclude that although the functional consequences of the controlled metal homeostasis within the brain of many species remains elusive, trace metal biology may not only play an important role in the nervous system of mammals but across the whole animal kingdom.

2.
Fungal Biol ; 124(5): 516-524, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32389315

RESUMO

Maintaining appropriate levels of trace elements during infection of a host is essential for microbial pathogenicity. Here we compared the uptake of 10 trace elements from 3 commonly-used laboratory media by 3 pathogens, Candida albicans, Cryptococcus neoformans and Aspergillus fumigatus, and a model yeast, Saccharomyces cerevisiae. The trace element composition of the yeasts, C. albicans, C. neoformans and S. cerevisiae, grown in rich (YPD) medium, differed primarily in P, S, Fe, Zn and Co. Speciation analysis of the intracellular fraction, which indicates the size of the organic ligands with which trace elements are complexed, showed that the ligands for S were similar in the three fungi but there were significant differences in binding partners for Fe and Zn between C. neoformans and S.cerevisiae. The profile for Cu varied across the 3 yeast species. In a comparison of C. albicans and A. fumigatus hyphae, the former showed higher Fe, Cu, Zn and Mn, while A. fumigatus contained higher P, S Ca and Mo. Washing C. albicans cells with the cell-impermeable chelator, EGTA, depleted 50-90 % of cellular Ca, suggesting that a large proportion of this cation is stored in the cell wall. Treatment with the cell wall stressor, Calcofluor White (CFW), alone had little effect on the elemental profile whilst combined Ca + CFW stress resulted in high cellular Cu and very high Ca. Together our data enhance our understanding of trace element uptake by pathogenic fungi and provide evidence for the cell wall as an important storage organelle for Ca.

3.
Metallomics ; 12(5): 794-798, 2020 May 27.
Artigo em Inglês | MEDLINE | ID: mdl-32232250

RESUMO

Although fish and seafood are well known for their nutritional benefits, they contain contaminants that might affect human health. Organic lipid-soluble arsenic species, so called arsenolipids, belong to the emerging contaminants in these food items; their toxicity has yet to be systematically studied. Here, we apply the in vivo model Caenorhabditis elegans to assess the effects of two arsenic-containing hydrocarbons (AsHC), a saturated arsenic-containing fatty acid (AsFA), and an arsenic-containing triacylglyceride (AsTAG) in a whole organism. Although all arsenolipids were highly bioavailable in Caenorhabditis elegans, only the AsHCs were substantially metabolized to thioxylated or shortened metabolic products and induced significant toxicity, affecting both survival and development. Furthermore, the AsHCs were several fold more potent as compared to the toxic reference arsenite. This study clearly indicates the need for a full hazard identification of subclasses of arsenolipids to assess whether they pose a risk to human health.

4.
Appl Microbiol Biotechnol ; 104(9): 3885-3896, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32140842

RESUMO

ß-Hydroxy-α-amino acids (ßH-AAs) are key components of many bioactive molecules as well as exist as specialised metabolites. Among these ßH-AAs, 4-fluorothreonine (4-FT) is the only naturally occurring fluorinated AA discovered thus far. Here we report overexpression and biochemical characterisation of 4-fluorothreonine transaldolase from Streptomyces sp. MA37 (FTaseMA), a homologue of FTase previously identified in the biosynthesis of 4-FT in S. cattleya. FTaseMA displays considerable substrate plasticity to generate 4-FT as well as other ß-hydroxy-α-amino acids with various functionalities at C4 position, giving the prospect of new chemo-enzymatic applications. The enzyme has a hybrid of two catalytic domains, serine hydroxymethyltransferase (S) and aldolase (A). Site-directed mutagenesis allowed the identification of the key residues of FTases, suggesting that the active site of A domain has a historical reminiscent feature in metal-dependent aldolases. Elemental analysis demonstrated that FTaseMA is indeed a Zn2+-dependent enzyme, the first example of pyridoxal phosphate (PLP) enzyme family fused with a metal-binding domain carrying out a distinct catalytic role. Finally, FTaseMA showed divergent evolutionary origin with other PLP dependent enzymes.

5.
Talanta ; 209: 120466, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31892068

RESUMO

The determination of total fluorine content using high-resolution graphite furnace continuum source molecular absorption spectrometry (HR- MAS) has been employed in a variety of samples for over 10 years. However, most of the samples analysed by HR- MAS are rich in fluoride, with negligible levels of organic fluorinated species. With an increase in concern surrounding per- and polyfluoroalkyl substances (PFASs), new methods to measure total fluorine of organofluorine using different techniques have been developed. However, no studies focused on PFASs behaviour in HR-MAS have been performed. As these compounds encompass a wide range of different structures, boiling points, decomposition temperatures and matrix interactions, a loss of accuracy can occur when an aqueous external calibration is performed using only one compound. To overcome this issue, an investigation into permanent modifiers for the graphite furnace was performed. After optimisation similar sensitivity for different PFCA was achieved when 400 µg of W was used as a permanent modifier together with an optimised temperature program. The relative deviation between the different PFCA standard slopes relative to the PFOA slope was lower than 15%. The instrumental limit of detection and quantification (LOD and LOQ, respectively) of total fluorine as total PFCA was 0.1 mg L-1 and 0.3 mg L-1, respectively, while the method LOD and LOQ (using solid phase extraction) was 0.3 µg L-1 and 1.0 µg L-1, respectively. The developed method gave satisfactory recoveries for the spiked PFCA into seawater, river water and effluent using PFOA calibration standards. The optimised method is useful for measuring extractable organofluorines (EOF) when only ionic PFASs such as PFCA are expected. When other organofluorines are expected, the results using HR GF-MAS should be taken with caution.

6.
Sci Total Environ ; 711: 134696, 2020 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-31852588

RESUMO

Studies aiming to limit bioaccumulation of arsenic (As) and cadmium (Cd) in rice grain has attracted global attention. In this study, simultaneous impact of zero valent iron (Fe°) and various water management regimes (continuous flooding (CF), alternate wetting and drying (AWD) and low water (LW)) on rice grain yield (GYM) and bioaccumulation of As and Cd in unpolished rice grain (URG) were investigated. Compared to respective control treatments, Fe° significantly reduced GYM under LW by 32% (p < 0.001) and significantly increased GYM under AWD by 24% (p = 0.009; F = 5.9) but had no significant effect on GYM under CF water management regime (p > 0.05). The grain harvest index was significantly higher in Fe° amended rice under AWD (67%; p < 0.001) and CF (35%; p = 0.001) compared to those without Fe° amendment. Fe° significantly reduced tAs in URG under LW by 32% (p < 0.017) and significantly increased tAs in URG under AWD by 37% (p = 0.007) but had no significant effect on tAs in URG under CF (p > 0.05). The Cd concentrations were significantly reduced by 51% (p = 0.002) and 61% (p < 0.003) in URG under LW and AWD respectively compared to the respective control treatments. The Dimethylarsinic acid (DMA) in unpolished rice (URG) under AWD (+Fe°) was significantly higher (p < 0.01; F = 11.3) compared to that accumulated in URG under AWD(-Fe°). Despite increasing As accumulation in AWD water management, simultaneous use of AWD water management and Fe° increased grain yield, enhanced accumulation of less toxic methylated As in rice grains and accumulated low Cd concentrations comparable to that attainable with CF water management indicating that simultaneous use AWD and Fe° can be effective in controlling Cd accumulation in paddies highly contaminated with Cd.


Assuntos
Oryza , Arsênico , Bioacumulação , Cádmio , Ferro , Metilação , Solo , Poluentes do Solo , Água , Abastecimento de Água
7.
ACS Omega ; 4(22): 19875-19879, 2019 Nov 26.
Artigo em Inglês | MEDLINE | ID: mdl-31788620

RESUMO

Photoisomerization of Irgacure PAG 103 followed by photocyclization and fragmentation leads to three tricyclic thieno[2,3-b]quinoline-4-carbonitrile heterocyclic compounds. The release of acid which can catalyze polymer resist modifications is indicated by the low pH of an aqueous extract. These reactions are discussed in view of possible mechanisms and how these might influence future design strategies.

8.
Anal Chim Acta ; 1079: 20-29, 2019 Nov 04.
Artigo em Inglês | MEDLINE | ID: mdl-31387711

RESUMO

This review covers analytical methods applied to the determination of none volatile sulphur-containing biological compounds. The classes of S-compounds include amino acids, proteins, lipids, carbohydrates and sulphur-containing metabolites. Techniques covered include element specific detectors as well as molecular specific detectors from X-ray absorption near-edge structure (XANES) to elemental and molecular mass spectrometers. The major techniques used are inductively coupled plasma mass spectrometry (ICP-MS) and high-resolution electrospray mass spectrometry (ESI-MS) in their various forms. Both techniques either individually or combined require the sample to be present in liquid form and therefore involve sample preparation usually extraction and depending on sample and molecular class studied potentially also derivatisation in addition to generally requiring chromatographic separation. Over recent years, detection limits achieved by elemental methods and computational methods to extract signals of sulphur-containing compounds out of the mass of data produced by molecular high-resolution mass spectrometers made significant gains. Still the determination of sulphur-containing compounds is challenging, but nowadays the methods have been developed well enough to allow application to real samples for absolute quantification of biomolecules such as proteins or lipids.


Assuntos
Técnicas de Química Analítica/métodos , Compostos de Enxofre/análise , Animais , Humanos , Enxofre/química , Compostos de Enxofre/química
9.
Artigo em Inglês | MEDLINE | ID: mdl-31284093

RESUMO

Engineered nanoparticles such as iron oxide (Fe3O4) nanoparticles (IONPs) offer several benefits in nanomedicine, notably as contrast agents in magnetic resonance imaging (MRI). Ferumoxytol, a suspension of IONPs (with a manufacturer's reported particle diameter of 27 nm-30 nm) was characterized as a standard by spiking into rat blood plasma and cell fractions. Nanoparticle separation, and characterisation was investigated with asymmetric flow field-flow fractionation (AF4) coupled online to ultraviolet-visible spectroscopy (UV-VIS), multi-angle light scattering (MALS) and inductively coupled plasma mass spectrometry (ICP-MS) detectors; also with single particle inductively coupled plasma mass spectrometry (spICP-MS) and transmission electron microscopy (TEM). MALS signal of pristine Ferumoxytol indicated radii of gyration (Rg) between 15 and 28 nm for the Fe-containing fraction and 30-75 nm for the non-Fe fraction. IONPs spiked into blood plasma indicated a polydisperse distribution between 40 nm - 120 nm suggesting matrix-induced size alterations. Spiking of the IONPs into cells showed a shift in ICP-MS Fe signal to 15 min, however the MALS signal was undetected within the Fe containing fraction of the IONPs suggesting NP loss due to membrane-particle attraction. spICP-MS analysis of IONPs spiked in rat plasma suggested the release of Fe-containing colloids into plasma causing an increase in diameter of IONPs to 52 ±â€¯0.8 nm; whereas no major variation in particle size and distribution of the IONPs spiked in cell fractions was observed (33.2 ±â€¯2.0 nm) suggesting non-alteration of the NP Fe core. A complementary application of microscopic, light scattering, and mass spectrometry techniques for the characterisation of NPs in challenging biological matrices like blood has been demonstrated.


Assuntos
Células Sanguíneas/química , Óxido Ferroso-Férrico/sangue , Fracionamento por Campo e Fluxo/métodos , Nanopartículas/análise , Espectrometria de Massas em Tandem/métodos , Animais , Espectrometria de Massas , Microscopia Eletrônica de Transmissão , Tamanho da Partícula , Plasma/química , Ratos
10.
Sci Total Environ ; 685: 259-272, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31176213

RESUMO

Macroalgae (seaweed) has been shown to be an effective environmental indicator. We investigate the trace element chemistry of macroalgae samples from locations along the Firth of Forth and Forth Estuary in Scotland. The overall trend in elemental abundance (Os ≪ Re < Ag < U < Cd < Co < Ni < Pb < Cu < As < Zn ≪ I), and changes along the estuary (seawards: increase As, I, Cd, U, Re, Os; decrease Pb, Cu; mid-estuary peak Zn; based on certain species), are controlled by a number of factors, including: salinity, mixing and macroalgal species differences. Within the same macroalgal species, some elemental abundances (As, I, Pb, Cu, Cd and U) are affected by mixing between freshwater riverine and North Sea marine saltwater. Additional mixing of natural and anthropogenic inputs from the surrounding geology and industry are also observed, affecting Zn, Ni, Co, Re and Os. Macroalgae is also an increasingly popular food, with some species harvested in the Firth of Forth. Iodine (67-5061 ppm), lead (0.047-4.1 ppm) and cadmium (0.006-0.93 ppm) macroalgal abundances are at safe levels for human consumption (WHO limits). However, many samples exceed the American (3 ppm) and Australian (1 ppm) limits for inorganic arsenic in macroalgae, with values ranging 0-67 ppm. In most of the samples, soaking and cooking the macroalgae reduced the inorganic arsenic content to within the American and Australian limits. However, this has further implications if the macroalgae is used to cook soups (e.g., Dashi), as the leached elements become a significant component of the soup.


Assuntos
Monitoramento Ambiental , Alga Marinha/química , Oligoelementos/análise , Poluentes Químicos da Água/análise , Arsenicais , Estuários , Salinidade , Água do Mar/química
11.
Anal Bioanal Chem ; 411(19): 4973-4985, 2019 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-31152227

RESUMO

Brown macroalgae Saccharina latissima (30-40 individuals) and Alaria esculenta (15-20 individuals) were collected from natural populations in winter in Iceland. The algal thalli were sectioned into different parts (e.g. holdfast, stipe, old frond, young frond and sori-containing frond sections) that differed in age and biological function. The work elucidated that arsenic (As) was not uniformly distributed within the two brown macroalgal species, with lower levels of total As were found in the stipe/midrib compared to other thallus parts. The arsenosugars mirrored the total arsenic in the seaweed mainly due to AsSugSO3 being the most abundant As species. However, arsenic speciation using parallel HPLC-ICP-MS/ESI-MS elucidated that the arsenic-containing lipids (AsL) had a different distribution where the arsenosugarphospholipids (AsPL) differed by approximately a factor of 4 between the sections containing the lowest and highest concentrations of AsPLs. When placing the sections in order of metabolic activity and an estimate of tissue age, there appeared to be a relationship between the activity and AsPLs, with lower levels of AsPLs in oldest parts. This is the first time such a relationship has been shown for AsLs. Hence, by applying sophisticated analytical techniques, it was possible to gain a deeper understanding of arsenolipids in seaweed.


Assuntos
Arsênico/metabolismo , Metabolismo dos Lipídeos , Feófitas/metabolismo , Alga Marinha/metabolismo , Cromatografia Líquida de Alta Pressão/métodos , Limite de Detecção , Feófitas/classificação , Plantas Comestíveis/metabolismo , Controle de Qualidade , Especificidade da Espécie , Espectrometria de Massas por Ionização por Electrospray/métodos
12.
Food Chem ; 286: 644-650, 2019 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-30827659

RESUMO

Brazil is a major producer of rice, but there is not enough information about As and Cd in rice grown under different conditions in this country. Here, As and Cd were determined by ICP-MS and species of As by HPLC-ICP-MS in Brazilian husked rice, covering diverse cultivars and regions, as well as upland and flooded production systems. Significant differences were observed for contents of both elements according to the origin of rice. All samples were below the maximum limit for Cd (400 µg/kg) set by national legislation, while nine samples presented total As above the legislation limit (300 µg/kg). From 24 samples analyzed for As species, 42% showed iAs above the European limit for production of food to infants (100 µg/kg). The total As content in samples from Mato Grosso state presented a maximum value of 6 µg/kg, which combined with low Cd content make interesting further studies.


Assuntos
Arsênico/análise , Cádmio/análise , Contaminação de Alimentos/análise , Oryza/química , Brasil , Cromatografia Líquida de Alta Pressão , Análise de Alimentos/métodos , Humanos , Lactente , Alimentos Infantis/análise , Espectrometria de Massas , Concentração Máxima Permitida
13.
Anal Chim Acta ; 1053: 22-31, 2019 Apr 11.
Artigo em Inglês | MEDLINE | ID: mdl-30712566

RESUMO

Although perfluorooctanesulfonic acid (PFOS) and perfluorooctanoic acid (PFOA) have been phased out, there is a plethora of per- or polyfluoroalkyl substances (PFAS) generated and only a small number of these compounds are currently being monitored in environmental and biological sample using molecular mass spectrometry (MS). Total fluorine determination has revealed that a substantial amount of fluorinated organic compounds has not been identified. Due to the small mass deficiency of fluorine, it is not an easy task to screen successfully all fluorinated compounds including those which are not easy ionisable, hence a novel fluorine-specific detector is needed. Here, inductively-coupled plasma mass spectrometry (ICPMS) was used for the first time for the detection of PFAS, by using the novel approach to transfer F- into a detectable [BaF]+ in the argon plasma. A reverse phase-high performance liquid chromatography (RP-HPLC) method was developed and then online coupled to ICPMS/MS for the fluorine-specific detection and simultaneously to electrospray MS (ESI-MS) to separate perfluorinated carboxylic acids (PFCA) and perfluorooctanesulfonic acid (PFOS). The calibration was linear and was element-specific with detection limits of 0.49 mg F L-1 under gradient elution method. As a proof of concept, PFCA standards in methanol were not fully neutralised to force the esterification and those solutions were measured using HPLC-ICPMS/MS-ESI-MS. The methyl esters were not detectable by ESI-MS but by ICPMS/MS. This illustrates that the undetectable fluorine-containing compounds were detected and quantified by the element-specific detection of ICPMS/MS. The analysis of spiked river water at sub-ppb level gave an acceptable recovery using a SPE-based preconcentration method. Since ICPMS/MS method is an element-specific detection, all non-fluorinated compounds interfering in ESI-MS were eliminated. Hence, HPLC-ICPMS/MS can be used as a non-targeted method of fluorinated compounds which helps the identification of novel fluorinated compounds in environmental and biological samples and helps with mining the ESI-MS data.

14.
Anal Chim Acta ; 1049: 20-28, 2019 Feb 21.
Artigo em Inglês | MEDLINE | ID: mdl-30612652

RESUMO

It is advisable to monitor and regulate inorganic arsenic (iAs) in food and feedstuff. This work describes an update and validation of a method of selective hydride generation (HG) with inductively coupled plasma mass spectrometry (ICP-MS) for high-throughput screening of iAs content in seafood samples after microwave-assisted extraction with diluted nitric acid and hydrogen peroxide. High concentration of HCl (8 M) for HG along with hydrogen peroxide in samples of a same concentration as used for extraction leads to a selective conversion of iAs to volatile arsine that is released and transported to the detector. A minor contribution from methylarsonate (≈20% to iAs) was found, while HG from dimethylarsinate, trimethylarsine oxide is substantially suppressed (less than 1% to iAs). Methodology was applied to Certified Reference Materials (CRMs) TORT-3, DORM-3, DORM-4, DOLT-4, DOLT-5, PRON-1, SQID-1 and ERM-CE278k, in some of them iAs has been determined for the first time, and to various seaweed samples from a local store. The results were always compared with a reference method and selectivity of iAs determination was evaluated. An inter-laboratory reproducibility was tested by comparative analyses of six fish and four seaweed samples in three European laboratories, with good agreement of the results. The method of HG-ICP-MS is sensitive (limit of detection 2 µg kg-1 iAs), well suited for screening of large number of samples and selective at iAs concentration levels at which maximum limits are expected to be set into EU legislation for marine samples.


Assuntos
Arsênico/análise , Proteínas de Peixes da Dieta/análise , Contaminação de Alimentos/análise , Hidrogênio/química , Espectrometria de Massas/métodos , Frutos do Mar/análise , Animais , Bivalves/química , Decápodes/química , Decapodiformes/química , Cação (Peixe) , Ácido Clorídrico/química , Peróxido de Hidrogênio/química , Limite de Detecção , Percloratos/química , Alga Marinha/química
15.
Environ Health Perspect ; 126(8): 84503, 2018 08.
Artigo em Inglês | MEDLINE | ID: mdl-30235424

RESUMO

The diet is emerging as the dominant source of arsenic exposure for most of the U.S. population. Despite this, limited regulatory efforts have been aimed at mitigating exposure, and the role of diet in arsenic exposure and disease processes remains understudied. In this brief, we discuss the evidence linking dietary arsenic intake to human disease and discuss challenges associated with exposure characterization and efforts to quantify risks. In light of these challenges, and in recognition of the potential longer-term process of establishing regulation, we introduce a framework for shorter-term interventions that employs a field-to-plate food supply chain model to identify monitoring, intervention, and communication opportunities as part of a multisector, multiagency, science-informed, public health systems approach to mitigation of dietary arsenic exposure. Such an approach is dependent on coordination across commodity producers, the food industry, nongovernmental organizations, health professionals, researchers, and the regulatory community. https://doi.org/10.1289/EHP3997.


Assuntos
Arsênico/efeitos adversos , Exposição Ambiental/efeitos adversos , Poluentes Ambientais/efeitos adversos , Dieta/efeitos adversos , Contaminação de Alimentos/análise , Humanos , Medição de Risco
16.
Food Chem ; 263: 180-185, 2018 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-29784305

RESUMO

A commercial arsenic field kit designed to measure inorganic arsenic (iAs) in water was modified into a field deployable method (FDM) to measure iAs in rice. While the method has been validated to give precise and accurate results in the laboratory, its on-site field performance has not been evaluated. This study was designed to test the method on-site in Malawi in order to evaluate its accuracy and precision in determination of iAs on-site by comparing with a validated reference method and giving original data on inorganic arsenic in Malawian rice and rice-based products. The method was validated by using the established laboratory-based HPLC-ICPMS. Statistical tests indicated there were no significant differences between on-site and laboratory iAs measurements determined using the FDM (p = 0.263, ά = 0.05) and between on-site measurements and measurements determined using HPLC-ICP-MS (p = 0.299, ά = 0.05). This method allows quick (within 1 h) and efficient screening of rice containing iAs concentrations on-site.


Assuntos
Arsênico/análise , Técnicas de Química Analítica/métodos , Oryza/química , Cromatografia Líquida de Alta Pressão , Contaminação de Alimentos/análise , Malaui , Espectrometria de Massas
17.
Anal Bioanal Chem ; 410(3): 661-667, 2018 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-28735451

RESUMO

This article is aimed at researchers interested in organic molecules which contain a heteroatom but who have never considered using inductively coupled plasma mass spectrometry (ICPMS) or who have used ICPMS for years and developed numerous methods for analysis of target elemental species. We try to illustrate (1) that ICPMS has been very useful for speciation analysis of metal(loid) target species and that there is now a trend to replace the costly detector with cheaper detection systems for routine target analysis, and (2) that ICPMS has been used and will be used even more in the future for non-targeted analysis of elements which are not normally associated with ICPMS analysis, such as non-metals such as sulfur, phosphorus, chlorine and fluorine. Graphical Abstract Starting with HPLC-ICPMS for non-targeted analysis of heteroatom containing molecules, once target molecule is identified alternative detectors can be used for routine measurements.

18.
Metallomics ; 9(10): 1429-1438, 2017 10 18.
Artigo em Inglês | MEDLINE | ID: mdl-28932845

RESUMO

Garlic (A. sativum) contains a large number of small sulphur (S)-containing metabolites, which are important for its taste and smell and vary with A. sativum variety and growth conditions. This study was designed to investigate the influence of different sulphur-fertilization regimes on low molecular weight S-species by attempting the first sulphur mass balance in A. sativum roots and bulbs using HPLC-ICPMS/MS-ESI-MS/MS. Species unspecific quantification of acid soluble S-containing metabolites was achieved using HPLC-ICP-MS/MS. For identification of the compounds, high resolution ESI-MS (Orbitrap LTQ and q-TOF) was used. The plants contained up to 54 separated sulphur-containing compounds, which constitute about 80% of the total sulphur present in A. sativum. The roots and bulbs of A. sativum contained the same compounds, but not necessarily the same amounts and proportions. The S-containing metabolites in the roots reacted more sensitively to manipulations of sulphur fertilization than those compounds in the bulbs. In addition to known compounds (e.g. γ-glutamyl-S-1-propenylcysteine) we were able to identify and partially quantify 31 compounds. Three as yet undescribed S-containing compounds were also identified and quantified for the first time. Putative structures were assigned to the oxidised forms of S-1-propenylmercaptoglutathione, S-2-propenylmercaptoglutathione, S-allyl/propenyl-containing PC-2 and 2-amino-3-[(2-carboxypropyl)sulfanyl]propanoic acid. The parallel use of ICP-MS/MS as a sulphur-specific detector and ESI-MS as a molecular detector simplifies the identification and quantification of sulphur containing metabolites without species specific standards. This non-target analysis approach enables a mass balance approach and identifies the occurrence of the so far unidentified organosulphur compounds. The experiments showed that the sulphur-fertilization regime does not influence sulphur-speciation, but the concentration of some S-containing compounds in roots is dependent on sulphur fertilization.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Alho/metabolismo , Espectrometria de Massas por Ionização por Electrospray/métodos , Compostos de Enxofre/análise , Compostos de Enxofre/metabolismo , Espectrometria de Massas em Tandem/métodos , Alho/química , Alho/crescimento & desenvolvimento , Compostos de Enxofre/química
19.
J Inorg Biochem ; 177: 82-88, 2017 12.
Artigo em Inglês | MEDLINE | ID: mdl-28926758

RESUMO

Despite its paramount role in the functioning of coastal ecosystems, relatively little is known about halogen metabolism in giant kelp (Macrocystis pyrifera). This is an important shortcoming given the potential implications for marine and atmospheric chemical processes in the wide distribution range of Macrocystis. The work presented here constitutes the first in depth investigation of the uptake, efflux, and of the physiological function of iodide in this important kelp species. Iodide uptake and efflux rates were measured in adult sporophytes of Macrocystis under normal and stressed (exogenous hydrogen peroxide and an elicitor-triggered oxidative burst) conditions. Kelp tissue took up iodide according to Michaelis-Menten type kinetics when incubated in seawater enriched with various concentrations of iodide. Upon the addition of exogenous hydrogen peroxide, simulating oxidative stress, a marked efflux of iodide occurred. In situ generation of hydrogen peroxide was elicited in Macrocystis upon the addition of oligomeric degradation products of alginate as well as arachidonic acid and methyl jasmonate constituting a defensive oxidative burst that could be linked to iodine accumulation. H2O2 was detected at the single cell level using dichlorohydrofluorescein diacetate, a fluorogenic probe capable of detecting intracellular H2O2. When assayed for vanadium haloperoxidase activity, several bromoperoxidase isoforms were detected as well as a single iodoperoxidase. Altogether, the results of this study show that Macrocystis has an elaborate iodine metabolism, which is likely significant for impacting iodine speciation in seawater around kelp beds and for volatile halogen emissions into the coastal atmosphere.


Assuntos
Iodetos/metabolismo , Iodo/metabolismo , Kelp/metabolismo , Macrocystis/metabolismo , Acetatos/metabolismo , Ácido Araquidônico/metabolismo , Ciclopentanos/metabolismo , Peróxido de Hidrogênio/metabolismo , Iodeto Peroxidase/metabolismo , Iodo/análise , Isoenzimas/metabolismo , Estresse Oxidativo , Oxilipinas/metabolismo , Peroxidases/metabolismo
20.
Chemosphere ; 186: 17-23, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28759813

RESUMO

Seaweed can accumulate inorganic arsenic (iAs) from seawater as hydrogen arsenate (HAsO42-) in place of the phosphate anion (HPO42-). While it is rapidly metabolised to organoarsenic species, predominantly arsenosugars and arsenolipids, iAs may be present in seaweed biomass and this poses a potential health concern for consumers of seaweed products. Here, the distribution of total (AsTOT) and iAs was determined in thallus parts of the kelp Laminaria digitata and the intertidal fucoid Ascophyllum nodosum (both Phaeophyceae) using inductively-coupled plasma mass spectrometry (ICP-MS) and high performance liquid chromatography - ICP-MS (HPLC-ICP-MS). AsTOT ranged from 36 to 131 mg kg-1 dry weight (DW) in L. digitata, and from 38 to 111 mg kg-1 DW in A. nodosum, with no statistically significant differences between different thallus parts. iAs was detected in all A. nodosum samples, comprising less than 1% of the AsTOT content. Concentrations of iAs in L. digitata were significantly higher, ranging from 2.2 to 87 mg kg-1, increasing through the thallus from the stipe to the decaying distal blades. iAs comprised more than 50% of AsTOT in the middle to decaying distal blades. This finding has potential implications for harvesting, processing and use of Laminaria digitata in agri-, food and health applications.


Assuntos
Arsênico/análise , Ascophyllum/química , Laminaria/química , Arsênico/metabolismo , Cromatografia Líquida de Alta Pressão , Irlanda , Espectrometria de Massas , Feófitas/metabolismo , Água do Mar/química , Alga Marinha/metabolismo
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