Arsenosugar phospholipids and arsenic hydrocarbons in two species of brown macroalgae

Fourteen arsenolipids, including 11 new compounds, were identified and quantified in two species of brown algae, Wakame (Undaria pinnatifida) and Hijiki (Hizikia fusiformis), by high resolution mass spectrometry, high performance liquid chromatography–mass spectrometry and gas chromatography–mass spectrometry. Both algal species contained arsenosugar-phospholipids as the major type of arsenolipid, and arsenic-hydrocarbons were also significant components, particularly in Hijiki. The origin of the various arsenolipids, and the possible significance of their relative quantities, is briefly discussed

Biosynthesis of arsenolipids by the cyanobacterium Synechocystis sp. PCC 6803

Although methylated arsenic and arsenosugars have been verified in various freshwater organisms, lipid-soluble arsenic compounds have not been identified. Here, we report investigations with the model organism cyanobacterium Synechocystis sp. PCC 6803 wild type and arsM (arsenic(III) S-adenosylmethionine methyltransferase) mutant strain, which lacks the enzymes for arsenic methylation cultured in various concentrations of arsenate (As-V). Although Synechocystis accumulated higher arsenic concentrations at the higher exposure levels, the bioaccumulation factor decreased with increasing As-V. The accumulated arsenic in the cells was partitioned into water-soluble and lipid-soluble fractions; lipid-soluble arsenic was found in Synechocystis wild type cells (3-35% of the total depending on the level of arsenic exposure), but was not detected in Synechocystis arsM mutant strain showing that ArsM was required for arsenolipid biosynthesis. The arsenolipids present in Synechocystis sp. PCC 6803 were analysed by high performance liquid chromatography-inductively coupled plasma-mass spectrometry, high performance liquid chromatography-electrospray mass spectrometry, and high resolution tandem mass spectrometry. The two major arsenolipids were characterised as arsenosugar phospholipids based on their assigned molecular formulas C47H88O14AsP and C47H90O14AsP, and tandem mass spectrometric data demonstrated the presence of the phosphate arsenosugar and acylated glycerol groups

Determination of water and lipid-soluble arsenic compounds in the commercial edible seaweed Hijiki (Hizikia fusiforme)

Se presentan los resultados obtenidos en los estudios de especiación de arsénico realizados sobre el alga comestible Hijiki. Los análisis se realizaron a través de métodos analíticos desarrollados en la UPM (España) y en la Universidad de Graz (Austria). La determinación de especies hidrosolubles se realizó mediante HPLC-(UV)-HG-AFS, previa extracción mediante MAE con agua desionizada. Por otro lado, la identificación y cuantificación de arsenolípidos se llevó a cabo mediante HPLC-ICPMS/ESMS, previa extracción con cloroformo:metanol y purificación mediante SPE

Toxicity of three types of arsenolipids : species-specific effects in Caenorhabditis elegans

This work was supported by the German Research Foundation (DFG), grant number SCHW 903/10-1 and the Austrian Science Fund (FWF), project number I2412-B21. MA was supported in part by grants from the NIEHS, R01ES10563 and R0107331.Peer reviewedPostprin

Salivary and gut microbiomes play a significant role in in vitro oral bioaccessibility, biotransformation, and intestinal absorption of arsenic from food

The release of a toxicant from a food matrix during the gastrointestinal digestion is a crucial determinant of the toxicant's oral bioavailability. We present a modified setup of the human simulator of the gut microbial ecosystem (SHIME), with four sequential gastrointestinal reactors (oral, stomach, small intestine, and colon), including the salivary and colonic microbiomes. Naturally arsenic-containing rice, mussels, and nori seaweed were digested in the presence of microorganisms and in vitro oral bioaccessibility, bioavailability, and metabolism of arsenic species were evaluated following analysis by using HPLC/mass spectrometry. When food matrices were digested with salivary bacteria, the soluble arsenic in the gastric digestion stage increased for mussel and nori samples, but no coincidence impact was found in the small intestinal and colonic digestion stages. However, the simulated small intestinal absorption of arsenic was increased in all food matrices (1.2-2.7 fold higher) following digestion with salivary microorganisms. No significant transformation of the arsenic species occurred except for the arsenosugars present in mussels and nori. In those samples, conversions between the oxo arsenosugars were observed in the small intestinal digestion stage whereupon the thioxo analogs became major metabolites. These results expand our knowledge on the likely metabolism and oral bioavailabiltiy of arsenic during human digestion, and provide valuable information for future risk assessments of dietary arsenic

Biosynthesis of arsenolipids by the cyanobacterium Synechocystis sp. PCC 6803

Although methylated arsenic and arsenosugars have been verified in various freshwater organisms, lipid-soluble arsenic compounds have not been identified. Here, we report investigations with the model organism cyanobacterium Synechocystis sp. PCC 6803 wild type and arsM (arsenic(III) S-adenosylmethionine methyltransferase) mutant strain, which lacks the enzymes for arsenic methylation cultured in various concentrations of arsenate (As-V). Although Synechocystis accumulated higher arsenic concentrations at the higher exposure levels, the bioaccumulation factor decreased with increasing As-V. The accumulated arsenic in the cells was partitioned into water-soluble and lipid-soluble fractions; lipid-soluble arsenic was found in Synechocystis wild type cells (3-35% of the total depending on the level of arsenic exposure), but was not detected in Synechocystis arsM mutant strain showing that ArsM was required for arsenolipid biosynthesis. The arsenolipids present in Synechocystis sp. PCC 6803 were analysed by high performance liquid chromatography-inductively coupled plasma-mass spectrometry, high performance liquid chromatography-electrospray mass spectrometry, and high resolution tandem mass spectrometry. The two major arsenolipids were characterised as arsenosugar phospholipids based on their assigned molecular formulas C47H88O14AsP and C47H90O14AsP, and tandem mass spectrometric data demonstrated the presence of the phosphate arsenosugar and acylated glycerol groups

Using Satellite-based Videoconferencing to Integrate the SatNEx Research Community

The SatNEx Project provides a pan-European multimedia network that may be used to rectify fragmentation in satellite communications research, by bringing together Europe’s leading academic institutions and research organisations in a cohesive and durable way. The resultant network provides a collective grouping of expertise and state-of-the-art laboratory facilities that would otherwise remain dispersed throughout Europe. This paper describes the Platform developed by the SatNEx community for use by the community to provide high-quality videoconferencing facilities, based on a satellite connectivity

Voltammetric determination of titanium, vanadium, and molybdenum using a carbon paste electrode modified with cetyltrimethylammonium bromide

Methods for the voltammetric determination of titanium, vanadium, and molybdenum using a carbon paste electrode modified in situ with cetyltrimethylammonium bromide (CTAB) are described. Titanium and vanadium are preconcentrated at the electrode surface via their anionic oxalate complexes from acidic solution at −1.2 and −0.9 V vs. the saturated calomel electrode. The accumulation process is due to in situ formation of an ion-exchanger at the electrode surface by adsorption of the surfactant, and to formation of ion-pairs or micellar congregates, since the concentration of CTAB is higher than the critical micellar concentration (CMC). Simultaneously during accumulation, titanium(IV)- and vanadium(V)-oxalates are reduced to their tri- and tetravalent states. The preconcentration of molybdenum(VI) was performed by adsorption and of ion-pairs of cetyltrimethylammonium and Mo(VI)-oxalates at a potential of −0.4 V. Molybdenum(VI)-oxalate is reduced to a mixed-valence compound of Mo(VI) and (V). Linear dependence of current on concentration exists in the ranges of 10 to 250 µg l−1 for titanium, 5 to 200 µg l−1 for vanadium, and 5 to 500 µg l−1 for molybdenum, when applying a preconcentration time of 1 min. The limit of detection (calculated as 3σ) is 0.1 µg l−1 Ti, 0.07 µg l−1 V, and 0.04 µg l−1 Mo with a deposition time of 10 min. The method presented in this report shows that CTAB is a suitable agent for modification of CPEs giving good reproducibility of results