Vibrio alginolyticus,a tetrodotoxin-producing bacterium,in the intestines of the fish Fugu vermicularis vermicularis

The influence of nutrient deprivation on cell-cycle progression was examined in two phytoplankton species, the diatom Thalassiosira weissflogii (actin) and the coccolithophorid Hymenomonas carterae (cocco II). The diatom was starved for nitrogen, silicon or both, whereas only nitrogen limitation was examined in H. carterae. In both species, nitrogen-starved cells were arrested in the early part of the cell cycle (G₁ phase). In the diatom, silicon-starvation arrested cells in late G₁ phase and also in the last part of the cell cycle (G₂+M). In all cases, cell-cycle arrest could be reversed by addition of fresh medium, but cell-cycling times during the first generation were increased in comparison to those in nutrient replete, steady-state growth conditions. These results supply evidence for simultaneous dual-nutrient limitation of population growth and provide a mechanistic interpretation for the division patterns observed in cultures where nutrients are supplied periodically.     

Occurrence of tetrodotoxin in the starfishes Astropecten polyacanthus and A. scoparius in the Seto Inland Sea

Two starfishes, togemomijigai Astropecten polyacanthus and momijigai A. scoparius were collected from the Seto Inland Sea in October 1983 through November 1984, and assayed for toxicity by the standard method for tetrodotoxin (TTX). Most of the 54 A. polyacanthus specimens assayed were toxic, with the highest toxicity score being 520 mouse units (MU) g^-1. All seven A. scoparius were toxic, with the highest score being 46 MU g^-1. The toxin from A. polyacanthus was purified by a method which consisted mainly of activated charcoal treatment, and chromatography on CM-Sephadex C-25 and Bio-Rex 70 columns. The purified starfish toxin showed a specific toxicity of 4 700 MU mg^-1, a value which was almost comparable to that of authentic TTX. From the thin-layer chromatographic and electrophoretic behavior, along with ¹H-NMR spectrum, A. polyacanthus toxin was identified as TTX.     

Evaluation of the procedures for the measurement of water solubility and n-octanol/water partition coefficient of chemicals results of a ring test in Japan

A ring test by 19 labolatories in Japan was carried out in 1984 for the evaluation of the experimental manuals for the measurements of water solubility and partition coefficient (n-octanol/water). The experimental data obtained by the procedures in the manuals were collected by Environmental Agency, Japan. In the measurement of water solubility, this manual applies a modified batch method (the glass beads technique), whereas the OECD Test Guidelines suggests the use of the column elution method for chemicals having water solubility lower than 10 mg/L. Anthracene and flouranthene were used as test chemicals for the measurement of water solubility, and γ -hexachlorocyclohexane (γ -HCH) and 1,2,3-trichlorobenzene were used for partition coefficient. Good agreements were observed at a practical basis between the OECD methods and our methods for the results of mesurements of water solubility and partition coefficient. We concluded that the present ring test showed an advantage of the use of the glass beads method which requires only simple apparatus in water solubility measurement, and the HPLC method is very useful to measure partition coefficient because of the simplicity of procedure and the wide range of measurement, especially at higher values of partition coefficient.     

A numerical method to predict flame fractal dimension during gas explosion

Accurate prediction of the flame propagation velocity during a gas explosion is essential to assess its consequences and to evaluate the risk level. The propagating premixed flame is self-turbulized due to the hydrodynamic instability, resulting in a fractal flame structure. It is therefore important for accurate prediction of flame speed to understand the flame’s fractal structure in detail and to predict its fractal dimension in particular. Numerical simulations of spherically-propagating flames have been previously attempted for such purposes. There are, however, difficulties to accurately predict the fractal dimension from the result of the numerical simulation of a spherically-propagating flame. In this study, we propose a method to easily predict the fractal dimension based on the numerical simulation of a planar flame. Planar flame propagation is simulated for different sizes of computational domain. The fractal dimension can be determined from the dependence of flame speed on computational domain size. The determined fractal dimension is favorably compared with previous experimental results.     

Recycling and consumption in Germany and Japan: a case of toilet paper

This paper compares the recycling attitudes of consumers in Germany and Japan, based on our nationwide questionnaires. We analyzed consumption behavior as well as recycling behavior in narrow sense, because it is important to study the former to see how the supply of recycled materials is balanced with the demand, particularly in Japan which exports little recycled materials. Toilet paper was adopted as a specific good for study, because consumers have options of buying virgin products and recycled products. It was found that German households pay for waste collection specifically and have higher recycling rates than Japanese households. On the other hand, similar figures in German and Japanese consumers were observed with regard to consumption of recycled products. Their purchasing criteria and preference on virgin and recycled products of toilet paper were examined by self-report and blind test with 2×2 experimental design for toilet paper (German versus Japanese, virgin versus recycled). Blind test showed that people prefer domestic and virgin products in both countries. Half of respondents rating virgin products guessed that the products contained recycled material. For Japanese, the material of the sample toilet paper, made from virgin pulp, seems to be a more determining factor than the nationality of products, i.e. made in Japan. On the other hand, for Germans, the domestic nature seems to be a more dominant factor than the material, i.e. made from virgin material. Canonical discriminant analysis in conjunction with logistic regression based on self-reporting data detected the characters ‘multiplied’, ‘appearance’ and ‘brand’ as major factors making the difference in preference between the two countries. The possible reasons causing the similarity and dissimilarity between the two countries are discussed with reference to the background history.     

Enhanced transformation of lead speciation in rhizosphere soils using phosphorus amendments and phytostabilization: an x-ray absorption fine structure spectroscopy investigation

To formulate successful phytostabilization strategies in a shooting range soil, understanding how heavy metals are immobilized at the molecular level in the rhizosphere soil is critical. Lead (Pb) speciation and solubility in rhizosphere soils of five different plant species were investigated using extended X-ray absorption fine structure (EXAFS) spectroscopy and chemical extraction. The EXAFS analysis indicated that Pb occurred as PbCO (37%), Pb sorbed to organic matter (Pb-org: 15%), and Pb sorbed to pedogenic birnessite and/or ferrihydrite (Pb-ox: 36%) in the bulk soil. Comparison of the EXAFS spectra between bulk and rhizosphere soils demonstrated notable differences in fine structure, indicating that Pb species had been modified by rhizosphere processes. The estimated proportion of PbCO (25%) in the buckwheat soil was smaller than the other rhizosphere soils (35-39%). The addition of P significantly reduced Pb solubility in the bulk and rhizosphere soil except in the rhizosphere of buckwheat, for which the Pb solubility was 10-fold greater than in the other P-amended soils. This larger solubility in the buckwheat rhizosphere could not be explained by the total Pb speciation in the soil but was presumably related to the acidifying effect of buckwheat, resulting in a decrease of the soil pH by 0.4 units. The reduced Pb solubility by P amendment resulted from the transformation of preexisting PbCO (37%) into Pb(PO)Cl (26-32%) in the bulk and rhizosphere soils. In the P-amended rhizosphere soils, Pb-org species were no longer detected, and the Pb-ox pool increased (51-57%). The present study demonstrated that rhizosphere processes modify Pb solubility and speciation in P-amended soils and that some plant species, like buckwheat, may impair the efficiency of Pb immobilization by P amendments.     

Nucleophilic substitution of poly(vinyl chloride) with iminoacetic acid and n-dodecanethiol

The modification of poly(vinyl chloride) was carried out with iminodiacetic acid (IDA, C₄H₇NO₄) and iminodiacetic acid dimethylester (IDADM, C₆H₁₁NO₄), as well as with n-dodecanethiol (DT, C₁₂H₂₆S) in the presence of K₂CO₃. The reaction was carried out at different temperatures below 100 °C with dimethyl formamide (DMF) and cyclohexanone as solvents. IDA did not show any reactivity, probably due to the dipolar character of the molecule. IDADM caused the elimination of HCl, while only substitution ratios of about 3 % were observed. However, the modification of PVC with DT resulted in a substitution rate of 18 % without elimination. DT-PVC showed excellent thermal properties, comparable with those of the unmodified polymer.     

Aryl hydrocarbon receptor activities of hydroxylated polycyclic aromatic hydrocarbons in recombinant yeast cells

Hydroxylated polycyclic aromatic hydrocarbons (OH-PAH) with less than four rings are frequently found in the environment, whereas the toxicities associated with these compounds remain unclear. In this study, aryl hydrocarbon receptor (AhR)–ligand binding activities of OH-PAH were investigated by using a recombinant yeast assay system. The majority of the OH-PAH tested showed AhR–ligand binding activities, especially, when the hydroxylated derivatives of naphthalene were incubated with recombinant yeast. The structure–activity relationship between AhR activity and molecular weight or the octanol–water partition coefficient value of OH-PAH displayed significant correlations. These findings indicate that the site and number of hydroxy-groups substituted on PAH skeleton apparently influenced the AhR – ligand binding activity in the recombinant yeast assay.     

Prediction of seawater solubility of aromatic compounds

The salting-out effect by seawater constituents on the water solubilities of 11 aromatic compounds, anthracene, pyrene, phenanthrene, biphenyl, naphthalene, p-nitrotoluene, p-toluidine, o-nitrophenol, m-nitrophenol, p-nitrophenol and phenol was investigated. A best fit equation (r = 0.965) for the salting-out parameters, K, and distilled water solubilities, S_o, at 20°C was found to be K = ?0.0298 log S_o + 0.114. Seawater solubilities, S, predicted for solutions of ionic strength, I, using the equation log S = (0.0298 I + 1) log S_o ? 0.114 I were in agreement with observed values within 13 % (average 4.8 %) and there were no significant differences between values from the Pacific Ocean seawater and those from 35 o/oo NaCl solutions. It was concluded that dissolved organic matter in seawater had an insignificant effect for the test chemicals.