Characterization of polychaetes inhabiting estuaries and inner bays by composition analysis of amino acids and lactate enantiomers.

In this study, we investigated the composition of free amino acids and lactate (Lac) in polychaetes in river estuaries and inner bays using chromatographic techniques. Both L-amino acids and D-amino acids (D-asparagine, D-alanine (D-Ala), D-serine, D-aspartic acid, and D-proline (D-Pro)) were detected, indicating that polychaetes contain some D-amino acids. Some polychaete species exhibited notable amino acid levels, such as glycine in Capitellidae sp. and Thelepus sp., D-Pro in Glycera sp., and ß-Ala in Scoletoma nipponica and Scoletoma sp.. High D-Lac levels were detected in Tylorrhynchus osawai and Hediste diadroma, (691 and 797 µmol/100 g-wet, respectively), with the D-form exceeding 98%. T. osawai was dominant in the upper tidal-sensitive zone, wherein other organisms were less abundant because of low salinity (3-8 PSU). Seasonal differences in the concentrations of components in T. osawai were observed, particularly a significant increase in D-Lac in the reproductive period. Notably, the D-Lac concentrations of T. osawai were higher upstream than downstream. Thus, D-Lac might be involved in strategies underlying adaptations to low salinity and reproductive activity. These results suggest that both the D-form of Lac and amino acids may play certain physiological roles in the life of polychaetes.

The effect of pioneer carrion beetles on the emission of volatile organic compounds and carrion insect community assembly.

Mechanisms of carrion insect succession have been interpreted separately from interspecific interactions between early and later colonists or from changes in volatile organic compounds perceived by insects resulting from the progression of decomposition. To link these perspectives, we examined through laboratory and field experiments whether the modification of volatile organic compounds by early colonists could be a mechanism of succession. In the laboratory experiment, we used Necrophila japonica (Coleoptera, Staphylinidae) as an early colonist and examined its effects on the emissions of important volatile attractants for carrion insects, dimethyl disulfide (DMDS) and dimethyl trisulfide (DMTS) from carcasses. We collected DMDS and DMTS, using the static headspace method, under the following conditions: (i) rat carcass, (ii) rat carcass with artificial damage to the abdomen, (iii) rat carcass fed on by 10 Ne. japonica individuals, and (iv) 10 Ne. japonica individuals, and analyzed the collected gases using a gas chromatograph-mass spectrometer. After 12 and 30 h, carcasses fed on by Ne. japonica emitted higher concentrations of DMDS and DMTS than in other conditions. In the field experiment, we examined the effects of DMDS and DMTS on the attraction of carrion insects using traps baited with a mixture of DMDS and DMTS, hexane (odors unrelated to carcasses), or an empty microtube. Traps baited with DMDS and DMTS attracted more necrophagous species and individuals than traps not baited with this combination. These results showed that accelerated emissions of DMDS and DMTS from carcasses caused by early colonists may contribute to community assembly during carrion insect succession.

Sources of Polycyclic Aromatic Hydrocarbons in Fecal Pellets of a Marphysa Species (Annelida: Eunicidae) in the Yoro Tidal Flat, Japan.

The fecal pellets of Marphysa sp. E sensu Abe et al. (2019) (Annelida, Eunicidae) living in the Yoro tidal flat (Ichihara, Chiba, Japan) contain high levels of polycyclic aromatic hydrocarbons (PAHs), and the concentrations rapidly decrease over time. To investigate the origin of the high-concentration PAHs in the fecal pellets and food sources of the worms, the PAH concentrations, carbon and nitrogen stable isotope ratios (δ13C and δ15N), total organic carbon, and total nitrogen for two types of sediment (sands and reduced muds), fecal pellets, and the body of the worms were determined. The PAH concentrations and chemical properties of the fecal pellets were similar to those of the reduced muds (20-30 cm sediment depth). The δ13C, δ15N, and C/N values of reduced muds were the same as the typical values of terrestrial C3 plants, suggesting that reduced muds were derived from terrestrial plants. These data indicated that the worms selectively take up reduced muds containing high levels of PAHs. The δ13C and δ15N values of the worm bodies indicated that the worms did not use the organic carbon derived from terrestrial C3 plants as primary nutrition. Taking into consideration their selective uptake of reduced muds, excretion, and subsequent rapid decrease of PAHs in the fecal pellets, the worms could contribute to the remediation of chemical pollutants in the tidal flat sediments.

Fluorescence Enhancement of Ethanolic Solution of Nitroarenes and Its Analytical Application.

When ethanolic solutions of 1-nitropyrene (1-NP) and 3-nitrobenzanthorone (3-NBA) were irradiated with intense light, which they absorb, for several minutes, the fluorescence characteristics of the solutions were significantly changed. After such preliminary irradiation, the fluorescence intensity of 1-NP increased immediately by a factor of 104 with a blue shift of 100 nm and that of 3-NBA 700 with a red shift of 10 nm. The findings were applied to high performance liquid chromatography with a fluorescence detector so that the two nitroarenes could be quantitatively analyzed by preliminary irradiation of their solutions before measurements. The calibration curves were linearly drawn over the concentration range from 1.0 × 10-9 to 1.0 × 10-7 M for 1-NP and 1.0 × 10-8 to 1.0 × 10-6 M for 3-NBA and the limits of detection were 2.3 pg for 1-NP and 28 pg for 3-NBA. From the results, fluorescence enhancement was found to be very effective for determining nitroarenes, being practically non-fluorescent and very important in environmental health-risk assessment, easily and sensitively. The mechanism of the fluorescence enhancement of 1-NP and 3-NBA was also discussed.

Valproic acid and ASK1 deficiency ameliorate optic neuritis and neurodegeneration in an animal model of multiple sclerosis.

Optic neuritis, which is an acute inflammatory demyelinating syndrome of the central nervous system, is one of the major complications in multiple sclerosis (MS). Herein, we investigated the therapeutic potential of valproic acid (VPA) on optic neuritis in experimental autoimmune encephalomyelitis (EAE), a mouse model of MS. EAE was induced in C57BL/6 mice by immunization with MOG35-55 and VPA (300mg/kg) was administered via intraperitoneal injection once daily from day 3 postimmunization until the end of the experimental period (day 28). VPA treatment suppressed neuroinflammation and decreased the clinical score of EAE at an early phase (from day 12-14 after immunization). We also examined the effects of apoptosis signal-regulating kinase 1 (ASK1), an evolutionarily conserved signaling intermediate for innate immunity, in EAE mice. ASK1 deficiency strongly suppressed microglial activation and decreased the clinical score of EAE at a late phase (day 25, 27 and 28 after immunization). When VPA was administered to ASK1-deficient EAE mice, the clinical score was suppressed in both early and late phases (from day 12-28 after immunization) and showed synergistic effects on protection of retinal neurons. Our findings raise intriguing possibilities that the widely prescribed drug VPA and ASK1 inhibition may be useful for neuroinflammatory disorders including optic neuritis and MS.

Polycyclic Aromatic Hydrocarbons in Sediments and Bivalves on the Pacific Coast of Japan: Influence of Tsunami and Fire.

Surface sediments and at least one edible bivalve species (Ruditapes philippinarum, Mytilus galloprovincialis, and Crassostrea gigas) were collected from each of seven intertidal sites in Japan in 2013. The sites had experienced varying levels of tsunami and fire disturbance following the major earthquake of 2011. Eight polycyclic aromatic hydrocarbons (PAHs) were identified and analyzed by gas chromatography-mass spectrometry. Total sediment PAH concentration (CT), the sum of the average concentrations of the eight PAHs, was 21-1447 µg kg-1-dry. Relative to the average level of one type of PAH in sediments collected around Japan in 2002 (benzo[a]pyrene = 21 µg kg-1-dry), five of the seven sites showed concentrations significantly lower than this average in 2013. The CTs for the three bivalves (134-450 µg kg-1-dry) were within the range of the previous reports (2.2-5335 µg kg-1-dry). The data suggest that the natural disaster did not increase PAH concentrations or affect the distribution within sediment or bivalves in Tohoku district. Although PAH concentrations at the sites pose no risk to human health, the findings highlight that the observed PAH levels derive from pre- rather than post-quake processes.

Separation of parabens on a zirconia-based stationary phase in superheated water chromatography.

A superheated water chromatography (SWC) method for the separation of alkyl esters of 4-hydroxybenzoic acid (parabens) using a zirconia-based stationary phase was developed and applied to real sample analysis. First, the SWC system was optimized in terms of the proper length of the preheating coil for establishing thermal equilibration of the mobile phase entering the column at the oven temperature. Next, the effect of the column temperature on the retention was investigated at 100-180°C. The elution time for all parabens decreased with increasing column temperature, and linear relationships between ln k and 1/T were obtained. At higher column temperatures, the elution time was further shortened because of the increased mobile-phase flow rate. Nevertheless, the loss of column efficiency at the higher flow rates was not significant. The application of the present method to the analysis of commercial lotions was then demonstrated. The quantification results obtained from SWC showed good agreement with those from a conventional HPLC method.

Destruxin E decreases Beta-amyloid generation by reducing colocalization of beta-amyloid-cleaving enzyme 1 and beta-amyloid protein precursor.

Alzheimer-disease-associated beta-amyloid (Abeta) is produced by sequential endoproteolysis of beta-amyloid protein precursor (betaAPP): the extracellular portion is shed by cleavage in the juxtamembrane region by beta-amyloid-cleaving enzyme (BACE)/beta-secretase, after which it is cleaved by presenilin (PS)/gamma-secretase near the middle of the transmembrane domain. Thus, inhibition of either of the secretases reduces Abeta generation and is a fundamental strategy for the development of drugs to prevent Alzheimer disease. However, it is not clear how small compounds reduce Abeta production without inhibition of the secretases. Such compounds are expected to avoid some of the side effects of secretase inhibitors. Here, we report that destruxin E (Dx-E), a natural cyclic hexadepsipeptide, reduces Abeta generation without affecting BACE or PS/gamma-secretase activity. In agreement with this, Dx-E did not inhibit Notch signaling. We found that Dx-E decreases colocalization of BACE1 and betaAPP, which reduces beta-cleavage of betaAPP. Therefore, the data demonstrate that Dx-E represents a novel Abeta-reducing process which could have fewer side effects than secretase inhibitors.

Characterization and determination of linear alkylbenzenesulfonates in environmental water samples by high-performance liquid chromatography with a hydrophilic polymer column and electrospray ionization mass spectrometric detection.

A liquid chromatography-mass spectrometry (LC/MS) method was developed for the separation and determination of linear alkylbenzenesulfonates (C10-C14 LAS) in environmental water samples using a hydrophilic polymer column (Shodex Mspak GF-310 4D). This method involves a solid-phase extraction of the LAS samples with a Sep-Pak PS-2 cartridge. The LAS components were separated on the column with a mobile phase of 29% (w/v) acetonitrile-water containing 0.8 mM di-n-butylammonium acetate and 0.2 M acetic acid, and were detected by mass spectrometry with electrospray ionization. Detection limits of the developed method based on selected ion monitoring (SIM) technique for the C10-C14 LAS standards were 13-47 ng L(-1). The concentrations of the C10-C14 LAS in the environmental water samples ranged between 5-317 microg L(-1) for a river water sample and 0.4-6.4 microg L(-1) for a seawater sample. Linear relationships between the logarithms of retention factors and the alkyl chain lengths for each phenyl positional isomer of LAS could successfully be used for the identification of the isomer peaks.