Influences of ambient carbon nanotubes on toxic metals accumulation in Daphnia magna.

With the rapid increase of carbon nanotube (CNT) applications, there are considerable concerns of their inevitable releases into the aquatic environments. CNTs may interact with and further influence the fate and transport of other pollutants such as toxic metals. In the present study, non-covalent and nontoxic dispersant polyvinyl pyrrolidone (PVP) was used to provide a relatively stable test solution for CNTs.

Inter-site differences of zinc susceptibility of the oyster Crassostrea hongkongensis.

Understanding the underlying mechanisms governing metal toxicity is crucial for predicting the risks and effects of metal pollutants. We hypothesized that metal toxicity is related to a threshold concentration of metabolically available metal but not to the total body metal concentration. Following a two-month laboratory Zn exposure, we characterized mortality and Zn bioaccumulation and subcellular partitioning in the oyster Crassostrea hongkongensis sampled from three sites with contrasting histories of Zn exposure and one multiple-metal contaminated site.

Facilitated bioaccumulation of cadmium and copper in the oyster Crassostrea hongkongensis solely exposed to zinc.

Exposure to one metal might have significant effects on the bioaccumulation of other metals. In the present study, we examined the possible effects of Zn exposure on the bioaccumulation of Cd and Cu in three populations of the oyster Crassostrea hongkongensis. We found that Zn exposure significantly enhanced the tissue concentrations of Cd and Cu in all populations, and the tissue concentrations of Cd and Cu were highly and positively related to the tissue Zn concentration.

Proteome pattern in oysters as a diagnostic tool for metal pollution.

The present study investigated whether proteome pattern of an oyster Crassostrea hongkongensis could be used as a diagnostic tool for contamination and toxicity of metals/metalloids in a real multiple metal-contaminated estuary. We collected oysters along a pollution gradient from highly contaminated to relatively clean sites. The oysters showed distinct contamination gradients of Cu, Zn and Cd.

Size-dependent uptake of silver nanoparticles in Daphnia magna.

The toxicity of silver nanoparticles (AgNPs) has been widely investigated, but the process of bioaccumulation such as uptake remains less studied. In the present study, we employed the radioisotope ((110m)Ag) to trace the behaviors of commercial AgNPs with three nominal particle sizes (20, 50, and 100 nm) and two surface coatings (citrate and tannic acid) in a model organism Daphnia magna . The size distributions of AgNPs in the medium increased continuously as the exposure time increased, especially for the smallest AgNPs (20 nm).

Reconstructing the biokinetic processes of oysters to counteract the metal challenges: physiological acclimation.

Oyster Crassostrea hongkongensis, a widely cultivated oyster species in Southern China, can accumulate metals (especially for Cu and Zn) to extraordinarily high concentrations (up to 3% of body dry weight). It remains unknown how they were acclimated to contaminated environment and built up such high metal concentrations in their bodies. A seven month transplantation experiment was conducted to rebuild the physiological process of acclimation in oysters to illustrate how they cope with increasing metal bioavailability.

Dietary toxicity of field-contaminated invertebrates to marine fish: effects of metal doses and subcellular metal distribution.

There is growing awareness of the toxicological effects of metal-contaminated invertebrate diets on the health of fish populations in metal-contaminated habitats, yet the mechanisms underlying metal bioaccumulation and toxicity are complex. In the present study, marine fish Terapon jurbua terepon were fed a commercial diet supplemented with specimens of the polychaete Nereis diversicolor or the clam Scrobicularia plana, collected from four metal-impacted estuaries (Tavy, Restronguet Creek, West Looe, Gannel) in southwest England, as environmentally realistic metal sources. A comparative toxicological evaluation of both invertebrates showed that fish fed S.

Thiol compounds induction kinetics in marine phytoplankton during and after mercury exposure.

We investigated the kinetics of Hg(II) and MeHg accumulation and the synthesis of phytochelatins (PCs), cysteine (Cys), glutathione (GSH), and γ-glutamylcysteine (γ-EC) in a marine diatom Thalassiosira weissflogii during a 3-h (short-term) and a 96-h (long-term) exposure period, and during a subsequent 96-h recovery period. MeHg induced the synthesis of a significant level of GSH, but it was Hg(II) that gave rise to significant levels of other non-protein thiol compounds. The thiol compounds Cys, γ-EC, and PC(2-3) were induced in T.

Contrasting mercury accumulation patterns in tilapia (Oreochromis niloticus) and implications on somatic growth dilution.

Dietary ingestion constitutes a major pathway for mercury (Hg) accumulation in freshwater fish, thus the ingestion rate (IR) may greatly influence the Hg bioaccumulation through its effect on Hg influx and other biokinetic processes. To explore the complex influence of IR, we conducted long-term bioaccumulation experiments by accurately controlling the IRs in the freshwater tilapia (Oreochromis niloticus). The dietary accumulation of both inorganic mercury (Hg[II]) and methylmercury (MeHg) in tilapia under different IRs was monitored over a period of 30 days by feeding the fish with uniformly radiolabeled crustaceans.

Principal curves for lumen center extraction and flow channel width estimation in 3-D arterial networks: theory, algorithm, and validation.

We present an energy-minimization-based framework for locating the centerline and estimating the width of tubelike objects from their structural network with a nonparametric model. The nonparametric representation promotes simple modeling of nested branches and n -way furcations, i.e.

Incorporating exposure into aquatic toxicological studies: an imperative.

The field of aquatic toxicology has been expanding rapidly in recent years. The ecotoxicological study of environmental toxicants encompasses three basic frameworks: environmental behavior/transport, bioavailability/bioaccumulation (exposure), and toxicity at different biological levels. Environmental risk assessments are then based on this knowledge to provide sound advice for environmental management and policies.

Metallothionein-like proteins turnover, Cd and Zn biokinetics in the dietary Cd-exposed scallop Chlamys nobilis.

In this study, we tested whether metallothionein-like proteins (MTLPs) affected the biokinetics of Cd and Zn in the scallops Chlamys nobilis following dietary Cd exposure. The scallops were fed Cd-contaminated diatoms for 8 or 40 days, and then the tissue Cd concentrations, MTLP turnover and their standing stocks, Cd and Zn kinetics were monitored. After 8 days of dietary Cd exposure (at 98 or 196 μg Cdg(-1)), their Cd levels were increased by 7.

The significance of chloride in the inhibitory action of disodium cromoglycate on immunologically-stimulated rat peritoneal mast cells.

Background: The microelectrode array (MEA) was used to investigate the pharmacological relevance of chloride (Cl-) ions in antigen-dependent mast cell activation and the inhibitory effect of disodium cromoglycate (DSCG) on mast cell activation.

Methods: The movements of ions across the cellular membrane and the potential relationship between Cl- channels and DSCG during immunological activation were investigated using the MEA. The results were then subsequently compared with the amount of histamine released from anti-IgE activated peritoneal mast cells.

Importance of surface coatings and soluble silver in silver nanoparticles toxicity to Daphnia magna.

Silver nanoparticles (AgNPs) are now widely used in antibacterial and personal care products. However, the underlying physicochemical mechanisms leading to the toxicity of AgNPs are still under debate. The present study revealed the different effects of three surface coatings (including lactate, polyvinylpyrrolidone, and sodium dodecylbenzene sulfonate, as AgNPs-L, AgNPs-P and AgNPs-S, respectively) on the acute toxicity of AgNPs to a model freshwater cladoceran Daphnia magna.

Aggregation-Induced Emission in a Hyperbranched Poly(silylenevinylene) and Superamplification in Its Emission Quenching by Explosives.

A silicon-containing hyperbranched polymer (hb-P1/2) with σ*-π* conjugation was prepared in a good yield and high molecular weight by rhodium-catalyzed alkyne polyhydrosilylation of 1,2-bis(4-ethynylphenyl)-1,2-diphenylethene (1) with tris(4-dimethylsilylphenyl)amine (2). The polymer was thermally stable, losing merely 5% of its weight when heated to ≈445 °C. Whereas hb-P1/2 was weakly luminescent when molecularly dissolved, it became highly emissive when supramolecularly aggregated, showing an aggregation-induced emission (AIE) phenomenon.

Sponges and sediments as monitoring tools of metal contamination in the eastern coast of the Red Sea, Saudi Arabia.

Sediments and sponges were collected from various locations along the eastern coast of the Red Sea, the Kingdom of Saudi Arabia. Total concentrations of Cd, Zn, Ag, Cu, Pb, As and Hg in the sediments were measured. Metal contamination was not significant in most of the studied sites and only one site was moderately polluted by Zn, Cu, and Pb.

Antagonistic interaction of mercury and selenium in a marine fish is dependent on their chemical species.

It is well-known that selenium (Se) shows protective effects against mercury (Hg) bioaccumulation and toxicity, but the underlying effects of Se chemical species, concentration, and administration method are poorly known. In this study, we conducted laboratory studies on a marine fish Terapon jurbua to explain why Hg accumulation is reduced in the presence of Se observed in field studies. When Se and Hg were administrated concurrently in the fish diets, different Se species including selenite, selenate, seleno-dl-cystine (SeCys), and seleno-dl-methionine (SeMet) affected Hg bioaccumulation differently.

Cadmium sensitivity, uptake, subcellular distribution and thiol induction in a marine diatom: Recovery from cadmium exposure.

Studies in the recovery from metal stress and the tolerance development to metal exposure of aquatic organisms are important for the understanding of epidemic pollution. In this study, the responses of a marine diatom, Thalassiosira nordenskioeldii, following recovery from environmental cadmium (Cd) stress were investigated. The diatoms were exposed to different concentrations of Cd for 7 days, and were then allowed different periods of time to recover.

Cadmium sensitivity, uptake, subcellular distribution and thiol induction in a marine diatom: exposure to cadmium.

The aims of this study were to (1) evaluate the changes in the Cd tolerance of a marine diatom after exposure under different Cd concentrations for various durations and (2) to explore the potential subcellular and biochemical mechanisms underlying these changes. The 72-h toxicity, short-term Cd uptake, subcellular Cd distribution, as well as the synthesis of phytochelatins (PCs) were measured in a marine diatom Thalassiosira nordenskioeldii after exposure to a range of free Cd ion concentrations ([Cd(2+)], 0.01-84nM) for 1-15 days.

Quantitation, visualization, and monitoring of conformational transitions of human serum albumin by a tetraphenylethene derivative with aggregation-induced emission characteristics.

Human serum albumin (HSA) is a major protein component of blood plasma, and its assay is of obvious value to biological research. We, herein, present a readily accessible fluorescent bioprobe for HSA detection and quantitation. A nonemissive tetraphenylethene derivative named sodium 1,2-bis[4-(3-sulfonatopropoxyl)phenyl]-1,2-diphenylethene (BSPOTPE) is induced to emit by HSA, showing a novel phenomenon of aggregation-induced emission (AIE).

Subcellular controls of mercury trophic transfer to a marine fish.

Different behaviors of inorganic mercury [Hg(II)] and methylmercury (MeHg) during trophic transfer along the marine food chain have been widely reported, but the mechanisms are not fully understood. The bioavailability of ingested mercury, quantified by assimilation efficiency (AE), was investigated in a marine fish, the grunt Terapon jarbua, based on mercury subcellular partitioning in prey and purified subcellular fractions of prey tissues. The subcellular distribution of Hg(II) differed substantially among prey types, with cellular debris being a major (49-57% in bivalves) or secondary (14-19% in other prey) binding pool.

A study of the relationship between pharmacologic preconditioning and adenosine triphosphate-sensitive potassium (KATP) channels on cultured cardiomyocytes using the microelectrode array.

The microelectrode array was used to study the pharmacologic preconditioning effect of adenosine triphosphate-sensitive channel activation using potassium channel openers (KCOs) on rat cardiomyocytes over 90 minutes of ischemia. Cell viability and electrophysiological changes between KCOs pretreated and untreated cardiomyocytes were compared. Ischemia caused significant increases in beat frequency, extracellular field potential amplitude, and propagation velocity of spontaneously beating untreated cardiomyocytes.

Mercury exposure in the freshwater tilapia Oreochromis niloticus.

Mercury (Hg) can be strongly accumulated and biomagnified along aquatic food chain, but the exposure pathway remains little studied. In this study, we quantified the uptake and elimination of both inorganic mercury [as Hg(II)] and methylmercury (as MeHg) in an important farmed freshwater fish, the tilapia Oreochromis niloticus, using (203)Hg radiotracer technique. The dissolved uptake rates of both mercury species increased linearly with Hg concentration (tested at ng/L levels), and the uptake rate constant of MeHg was 4 times higher than that of Hg(II).

Enhanced electrical conductivity of nanocomposites containing hybrid fillers of carbon nanotubes and carbon black.

Nanocomposites reinforced with hybrid fillers of carbon nanotubes (CNTs) and carbon black (CB) are developed, aiming at enhancing the electrical conductivity of composites with balanced mechanical properties while lowering the cost of the final product. Epoxy-based nanocomposites were prepared with varying combinations of CNTs and CB as conducting fillers, and their electrical and mechanical properties were evaluated. It was shown that the addition of CNTs in CB composites enhanced the electrical conductivity of composites: a low percolation threshold was achieved with 0.

Controls of dissolved organic matter and chloride on mercury uptake by a marine diatom.

The effects of natural dissolved organic carbon (DOC) from different origins (estuarine, coastal, and diatom decomposed) and chloride (Cl) on the uptake of inorganic mercury [Hg(II)] and methylated mercury (MeHg) by the marine diatom Thalassiosira pseudonana was investigated using radiotracer techniques. We first developed a new method to remove the surface adsorbed mercury and quantified the intracellular mercury uptake by the diatoms. The dominant mercury species (DOC or chloride complexes, based on the mercury speciation phase diagrams) was controlled by the concentrations of DOC and Cl(-), which could explain the effects of DOC and Cl(-) on mercury uptake.