Radiocesium concentrations in great cormorants (Phalacrocorax carbo) between 2011 and 2012 after the Fukushima Dai-ichi Nuclear Power Plant accident.

Radiocesium concentrations were measured in the pectoralis muscles of great cormorant (n = 36) collected from Gunma Prefecture between November 2011 and July 2012. The 137Cs contamination levels in great cormorant were consistent with the 137Cs deposition levels on ground soil and 137Cs concentrations in freshwater fishes. The Tag of great cormorants were comparable with those of other birds except for copper pheasant.

The host-binding domain of the P2 phage tail spike reveals a trimeric iron-binding structure.

The adsorption and infection of bacteriophage P2 is mediated by tail fibres and tail spikes. The tail spikes on the tail baseplate are used to irreversibly adsorb to the host cells. Recently, a P2 phage tail-spike protein, gpV, was purified and it was shown that a C-terminal domain, Ser87-Leu211, is sufficient for the binding of gpV to host Escherichia coli membranes [Kageyama et al. (2009), Biochemistry, 48, 10129-10135]. In this paper, the crystal structure of the C-terminal domain of P2 gpV is reported. The structure is a triangular pyramid and looks like a spearhead composed of an intertwined ß-sheet, a triple ß-helix and a metal-binding region containing iron, calcium and chloride ions.

Quantification of trace elements in natural samples by electrospray ionization mass spectrometry with a size-exclusion column based on the formation of metal-aminopolycarboxylate complexes.

Metal ions were determined by ESI-MS in the negative ion mode as monovalent negative ions of their aminopolycarboxylic acid (APC) complexes, e.g., [Al(cydta)](-), [Pb(Hcydta)](-), where excess amounts of the APC agents were added to sample solutions. Among several APCs studied, we chose trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CyDTA) as the best chelating agent because of higher stabilities and higher sensitivities of the complexes. The ionization efficiency of these metal complexes was strongly affected by the presence of matrix salts, e.g., NaCl, KNO(3), and etc. Thus, a size exclusion column (Sephadex G-10) was used for the online separation of the metal-APC complexes from other matrix salts. This method was successfully applied to the quantitative analyses for total amounts of Al, Ni, Cu, Zn, and Pb in the biological certified reference materials, olive leaves (BCR-062) and plankton (BCR-414). The detection limits of the present methods for these elements were several to several ten nanomolar levels. Moreover, this approach was extended to determine ultratraces of fluoride based on the formation of the ternary complex of aluminum, fluoride and nitrilotriacetic acid (NTA), i.e., [AlF(nta)](-). Its detection limit was 10 nM and was 2 orders of magnitude better than that of a fluoride ion selective electrode method. This method was applied to determine fluoride in tap water, river water, and green tea samples.

A Liquid-core Liquid-cladding Optical Waveguide Based on Thermal Gradients across the Laminar Flow of Water in Capillary Tubing.

A liquid-core liquid-cladding optical waveguide based on thermal gradients across laminar flow was built with the laminar flow of water in a stainless capillary tube placed in a heat source. Its characteristics were studied with both experiments and a computational fluid dynamics simulation, firstly showing that it had the nature of a graded index optical fiber.

Adsorption Behavior of Curcumin onto Cetyltrimethylammonium Chloride Reverse Micelles Immobilized on a Glass Surface As Studied by Polarized Visible Attenuated Total Reflection Spectrometry with a Glass Slab Optical Waveguide.

Polarized visible attenuated total reflection spectrometry with a glass slab optical waveguide revealed that when a hydrophobic dye, curcumin, was adsorbed onto the cetyltrimethylammonium chloride (CTAC) reverse micelles immobilized on a glass surface, in an undissociated form, the curcumin was perpendicular to the surface plane, while in a dissociated form, the curcumin was parallel to the plane. This implies that the former may be located in the CTAC monolayer while the latter may be located in the reverse micellar water phase immobilized on the plane.

Identification of aluminum species in an aluminum-accumulating plant, hydrangea (Hydrangea macrophylla), by electrospray ionization mass spectrometry.

The use of electrospray ionization mass spectrometry (ESI-MS) in negative ion mode was investigated as a direct probe for identifying Al species in Al-accumulating hydrangea (Hydrangea macrophylla) samples. Cell sap solutions of hydrangea leaves were purified using Sephadex G-10 liquid chromatography and each fraction was analyzed using ESI-MS and ESI-MS/MS to identify Al species. In hydrangea leaves, a 1:1 Al-citrate complex was found as [AlH(-1)cit](-) (m/z 215), where H(3)cit denotes citric acid. This result is consistent with that of Ma et al. who used (27)Al-NMR.

Development of a Microfluidic System Comprising Dialysis and Secretion Components for a Bioassay of Renal Clearance.

We have developed a microfluidic bioassay system that mimics glomerular filtration and tubular secretion in the kidney. The system consists of a peristaltic micropump (heart), a dialysis component (renal corpuscle), and a secretion component (renal proximal tubule). Analytes were separated by size using a dialysis membrane in the dialysis component. Model cells were cultured on a membrane in the secretion component, and active transport mediated by P-glycoprotein (P-gp) was confirmed using the P-gp substrate rhodamine 123 with or without the P-gp inhibitor quinidine sulfate. The system achieved both size separation and selective transport by P-gp on a single microchip. This proof-of-concept model may find applications in drug excretion assays, including studies of drug-drug interactions during tubular secretion.

Radiocesium dynamics in the aquatic ecosystem of Lake Onuma on Mt. Akagi following the Fukushima Dai-ichi Nuclear Power Plant accident.

Understanding ecosystem dynamics of radionuclides is necessary to ensure effective management for food safety. The Fukushima Dai-ichi Nuclear Power Plant (FDNPP) accident on March 11, 2011 released large amounts of radiocesium (134Cs and 137Cs) and contaminated the environment across eastern Japan. In this study, we aimed to elucidate the temporal dynamics of 137Cs in the aquatic ecosystem of Lake Onuma on Mt. Akagi. The effective ecological half-life (Teff) of 137Cs in fishes, western waterweed (Elodea nuttallii), seston (phytoplankton and zooplankton), and lake water was estimated using survey data of 137Cs concentration collected from 2011 to 2016, and single- and two-component decay function models (SDM and TDM, respectively). The decay processes of 137Cs concentrations in wakasagi (Hypomesus nipponensis), pale chub (Zacco platypus), phytoplankton, and total 137Cs concentrations of the water column (WC) in the lake were well suited by the TDMs. The Teff in the fast component of the TDMs in these samples ranged from 0.49 to 0.74years. The Teff in the slow component of the TDMs could converge towards the physical half-life of 137Cs. Nearly five and a half years after the FDNPP accident, we concluded that 137Cs concentrations approached a state of dynamic equilibrium between some aquatic organisms (wakasagi, pale chub, and phytoplankton) and the environment (lake water). However, the decay processes of 137Cs concentrations in Japanese dace (Tribolodon hakonensis), western waterweed, zooplankton, and particulate- and dissolved-forms in the WC were better predicted for the SDM. The total 137Cs concentrations in inflowing river and spring waters were one to two orders of magnitude lower than lake water under normal flow conditions. However, particulate 137Cs contamination level in the river water was high after heavy rains. Overall, 137Cs contamination levels have significantly decreased in Lake Onuma, but monitoring surveys should be continued for further understanding of the reduction processes.

Development of a Multichannel Dialysis Microchip for Bioassay of Drug Efficacy and Retention.

Here, we developed a multichannel dialysis microchip having three sets of dialysis systems, which consisted of three independent circulation channels with a common micropump. Each dialysis system was composed of a pneumatic micropump (heart), dialysis unit (renal corpuscle), and cell culture chamber (drug target) as well as circulation and dialysate channels to mimic the circulation system. Small molecules were successfully separated in parallel from macromolecules at the dialysis components. Anticancer tests using this microchip showed results that considered both serum protein-binding nature and drug activity. In the anticancer bioassay, the multichannel chip showed similar reproducible and reliable results as those of the single-channel system but with higher throughput.

Direct Detection of Aqueous CO2 by Infrared Waveguide Spectroscopy with an Amorphous Fluoropolymer Coating Rod.

Infrared waveguide spectroscopy using a sapphire rod coated with an amorphous fluoropolymer (Cytop, Asahi Glass Co., ltd, Japan) has been developed in order to directly observe CO2 in aqueous solutions. Since the amorphous fluoropolymer has a relatively high gas-permeability and hydrophobic feature, the aqueous CO2 transmits into the amorphous fluoropolymer coating film, but water cannot penetrate into the film. Good linearity of calibration curves for CO2 in the gas and the aqueous solution were obtained.

Development of Tetrahydrofuran/Water Optical Waveguide and Its Application to the Observation of Extraction Behavior of 1-Anilino-8-naphtalene Sulfonate at the Tetrahydrofuran/Water Interface.

A stable two-phase sheath flow using tetrahydrofuran (THF) for an inner flow and water for an outer flow was formed in a glass capillary, and worked as a stable liquid-core/liquid-cladding optical waveguide (THF/water LLW). Although THF and water were miscible with any ratio, the length of the stable THF/water LLW at 0.9 - 2.1 cm s-1 reached at least 150 mm. The THF/water LLW was applied to the observation of extraction behavior of solvatochromic fluorescence dye, 1-anilino-8-naphtalene sulfonate (ANS), through the THF/water interface. ANS was added to the water phase (clad solution) and its fluorescence, which was excited with the guided light (355 nm) through the LLW, was observed by changing the position of the detector. While the ANS stayed in the region of 70% THF to the end of the LLW without the addition of cationic surfactant, hexadecyltrimethylammonium ion (CTA+) at pH 3 and 11, the ion-pair of ANS and CTA+ was extracted into the higher concentration region of THF with the addition of CTA+ at pH 11.

Fractionation of radiocesium in soil, sediments, and aquatic organisms in Lake Onuma of Mt. Akagi, Gunma Prefecture using sequential extraction.

The Fukushima Daiichi Nuclear Power Plant (FDNPP) accident has resulted in the contamination of the environment in Gunma Prefecture with radioisotope cesium (radio-Cs, 134Cs and 137Cs). Concentrations of radio-Cs >500Bqkg-1 were found in wakasagi (Hypomesus nipponensis) in Lake Onuma at the top of Mount (Mt.) Akagi in August 2011. To explain the mechanism of this contamination, monitoring studies have been conducted around Lake Onuma by measuring radio-Cs concentrations in samples of fish, aquatic plants, plankton, lake water, lake sediments, and surrounding soil. The leachability of radio-Cs was evaluated using sequential extraction by Tessier et al. The total concentration of radio-Cs in Lake Onuma ecosystems decreased gradually with time. In the brown forest soil, radio-Cs concentrations of 2000 to 6000Bqkg-1 were detected. The abundance ratio of the easy-elution form (exchangeable and carbonate forms) in the samples was <10%. The concentrations in phytoplankton samples were 3-6 times higher than those in wakasagi samples. The ratios of easy-elution forms increased by the rank in the food chain; 37% in phytoplankton, 78% in zooplankton, and 97% in wakasagi. It is likely that the lower ratio of the easy-elution form in phytoplankton is related to the adsorption of radio-Cs on suspended substances in the lake, as suggested by the analyses of aluminum and titanium in the phytoplankton, zooplankton, and wakasagi samples. The high concentrations of radio-Cs in wakasagi would be related also to the characteristics of closed mountain lakes.

Preparation of low flow-resistant methacrylate-based monolithic stationary phases of different hydrophobicity and the application to rapid reversed-phase liquid chromatographic separation of alkylbenzenes at high flow rate and elevated temperature.

Low flow-resistant alkyl methacrylate-based monolithic stationary phases of different hydrophobicity were constructed for reversed-phase capillary liquid chromatography by thermally initiated radical polymerization of respective methacrylate ester monomer with different alkyl chain (C2, C4, C6, C12, C18) and ethylene glycol dimethacrylate (EDMA) in a 250 microm i.d. fused silica capillary. The hydrophobicity was basically controlled by changing the length and/or the density of the alkyl-chain, while the composition and the ratio of porogenic solvent were adjusted to obtain highly permeable rigid monoliths with adequate column efficiency. Among the prepared monolithic stationary phases, C18-methacrylate monoliths polymerized from a binary porogenic solvent of isoamyl alcohol and 1,4-buthandiol exhibited the most promising performance in terms of hydraulic resistance and column efficiency. The pressure drops of 20-cm long monolithic columns were below approximately 0.4 MPa at a normal linear velocity of 1mm/s (a flow rate of 3 microL/min), and the numbers of theoretical plates for alkylbenzenes mostly exceeded 3000 plates/20 cm. The produced monolithic columns had good mechanical strength for high pressure and temperature, and could be properly operated even at a temperature of 80 degrees C and at a pressure of at least 33 MPa. At 80 degrees C, the theoretical plate numbers reached 6000 plates/20 cm because of the enhanced mass transfer. Due to the novel hydraulic resistance and mechanical strength, the separation time could be reduced 120-fold simply by raising the flow rate and column temperature.

Liquid core waveguide spectrophotometry for the sensitive determination of nitrite in river water samples.

A flow injection analysis system was built with a liquid core waveguide spectrophotometric detector using an 80 cm Teflon AF-1600 capillary tube (2,2-bistrifluoromethyl-4,5-difluoro-1,3-dioxole/tetrafluoroethylene). The system was applied to determine nitrite ion in river water samples. The lower limit of detection for nitrite was 2.1 nmol dm(-3) (0.1 ng dm(-3) as NO(2)(-)) and the relative standard deviation of measurements was typically 0.56% (n = 5) at 0.21 micromol dm(-3).

Molasses melanoidin promotes copper uptake for radish sprouts: the potential for an accelerator of phytoextraction.

Phytoextraction has been proposed as an alternative remediation technology for heavy metal contamination, and it is well known that chelators may alter the toxicity of heavy metals and the bioavailability in plants. Our previous work demonstrated that an adsorbent-column chromatography can effectively separate melanoidin-like product (MLP) from sugarcane molasses. The aim of this study was to examine the chelating property of MLP and to evaluate the facilitatory influence on the phytoextraction efficiency of Japanese radish. The result showed that MLP binds to all the metal ions examined and the binding capacity of MLP toward Cu(2+) seems to be the highest among them. The metal detoxification by MLP followed the order of Pb(2+) > Zn(2+) > Ni(2+) > Cu(2+) > Fe(2+) > Cd(2+) > Co(2+). Furthermore, in the phytoextraction experiment using copper sulfate, the application of MLP accelerated the detoxification of copper and the bioavailability in radish sprouts. Thus, these results suggest that MLP possesses the potential for an accelerator of phytoextraction in the copper-contaminated media.

Patterned Co-culture of Live Cells on a Microchip by Photocrosslinking with Benzophenone.

The patterned coculture of different types of living cells in a microfluidic device is crucial for the analysis of cellular interactions and cell-cell communication. In the present study, cell patterning was achieved by photocrosslinking benzophenone derivatives in a microfluidic channel. Optimization of UV irradiation conditions enabled successful fixation of live cells. In addition, patterning and co-culture of non-adherent K562 cells and adherent RF-6A cells was achieved by successive rounds of patterning. The present approach is expected to be useful for the development of in vitro methods for studying cell signaling.

A novel method for determination of inorganic oxyanions by electrospray ionization mass spectrometry using dehydration reactions.

Novel methods for the determination of inorganic oxyanions by electrospray (ES) ionization mass spectrometry have been developed using dehydration reactions between oxyanions and carboxylic acids at the ES interface. Twelve oxyanions (VO3 (-) , CrO4 (2-) , MoO4 (2-) , WO4 (2-) , BO3 (3-) , SiO3 (2-) , SiO4 (4-) , AsO4 (4-) , AsO2 (-) , SeO4 (2-) , SeO3 (2-) and NO2 (-) ), out of 16 tested, reacted with at least one of four aminopolycarboxylic acids, i.e. iminodiacetic acid (IDA), nitrilotriacetic acid (NTA), trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid and triethylenetetramine-N,N,N',N″,N'″,N'″-hexaacetic acid, at the ES interface to produce the dehydration products that gave intense mass ion responses, sufficient for trace analysis. As examples, trace determinations of Cr(VI) and silica in water samples were achieved after online ion exchange chromatography, where the dehydration product of CrO4 (2-) and NTA (m/z 290) and that of SiO4 (4-) and IDA (m/z 192) were measured. The limits of detection of the respective methods were 17 nM (0.83 ng Cr/ml) for Cr(VI) and 0.17 µM (4.8 ng Si/mL) for SiO4 (4-) .

Characteristics of a liquid/liquid optical waveguide using sheath flow and its application to detect molecules at a liquid/liquid interface.

The formation conditions and characteristics of a liquid/liquid optical waveguide (LLW) were studied using a two-phase sheath flow, where the inner organic phase flow acted as the core and the outer aqueous flow acted as the clad. In immiscible solvent systems, i.e., toluene/water and diethyl ether/water systems, the LLWs were formed in the range of higher than ca. 600 of the Reynolds number (Re), where the linear velocity of the organic solvent was much higher than that of the aqueous solution. On the other hand, in a miscible solvent system, i.e., a tetrahydrofuran/water system, a stable LLW was formed in the range of a much lower Re than in immiscible systems. Moreover, the molecules at the toluene/water interface of the LLW were observed with both fluorescence and absorbance measurement systems. In particular, the change in the fluorescence spectrum of 1-anilino-8-naphthalenesulfonate (ANS) at the interface within 1 ms was observed by this method, indicating the usefulness of the LLW for a fast kinetic study of a liquid/liquid interface.

Evaluation of an ODS column modified with zwitterionic/nonionic mixed surfactants and its application to direct injection determination of inorganic anions.

An octadecylsilica (ODS) column modified with zwitterionic/nonionic mixed surfactants was evaluated for the direct injection determination of inorganic anions in biological fluids by ion chromatography. A zwitterionic surfactant (sulfobetaine-type) and a nonionic surfactant (polyoxyethylene-type) were used for a stationary-phase modification. When aqueous electrolyte solutions with concentrations of sub-mM to several mM were used as a mobile phase, the zwitterionic surfactant coated on the ODS surface exhibited unique separation selectivity for ionic species, while the nonionic surfactant coated on the ODS might have formed a hydrophilic network over the ODS surface and restricted matrix proteins from adsorbing on the stationary phase. Consequently, the mixed surfactant-modified column system allowed an efficient ion chromatographic separation of inorganic anions as well as a size-exclusive removal of column-fouling proteins. This separation system was applied to the direct injection determination of UV-absorbing anions in human saliva. The detection limits for nitrite, nitrate, iodide and thiocyanate were 3.1, 2.7, 4.5 and 25 microM, respectively, with UV detection at 210 nm (injection volume; 20 microl), and their relative standard deviations for 5 replicate measurements of saliva samples spiked with 100 microM each of those anions were 1.4, 0.9, 2.2 and 5.5%, respectively.

Electrospray ionization mass spectrometry for the quantification of inorganic cations and anions.

Recent studies from our laboratory on electrospray ionization mass spectrometry (ESI-MS) for the quantification of inorganic cations and anions are reviewed. Metal ions were determined by ESI-MS in negative-ion mode as monovalent negative ions of their aminopolycarboxylate (APC) complexes, where excess amounts of the APC agents were added to sample solutions. Among the APCs studied, we found trans-1,2-diaminocyclohexane-N,N,N',N'-tetraacetic acid (CyDTA, the chemical forms in a complex were expressed as H(n)cydta(n-4)) as the best chelating agent. A size exclusion column was used for on-line separation of the metal-APC complexes from matrix salts in samples. Total amounts of Al, Ni, Cu, Zn, and Pb in the biological certified reference materials (CRM), Olive Leaves (BCR-062) and Plankton (BCR-414), and in a soil CRM (JSAC-0401) were successfully determined by the proposed method. Halide ions (X(-) = F(-), Cl(-), Br(-) and I(-)) and cyanide (CN(-)) were determined by ESI-MS based on the formation of ternary complexes of metals, chelating agents and the analyte anions. Negative ions of the ternary complexes of group 13 elements, nitrilotriacetic acid (NTA, H(n)nta(n-3)), and halides, i.e., [AlF(nta)](-) for F(-), and [InX(nta)](-) for other halides, were measured; the limits of detection (LODs) were 10 nmol dm(-3) for F(-), 0.31 µmol dm(-3) for Cl(-), 3.8 nmol dm(-3) for Br(-), and 1.6 nmol dm(-3) for I(-), respectively. In the case of CN(-), an LOD of 20 nmol dm(-3) was obtained based on measurements of the ternary complex of Cu(II), CN(-) and 4-(2-pyridylazo)resorcinol (PAR, Hnpar(n-2)), i.e., [(63)Cu(II)(CN)(par)](-) (m/z 302). Moreover, quantitative methods for Cr(VI) and Cr(III) by ESI-MS were developed, where HCrO4(-) (m/z 117) for Cr(VI) and [Cr(III)(cydta)](-) for Cr(III) were used for measurements.