Solventless Delignification of Wood Flour with TiO2/poly(ethylene oxide) Photocatalyst System

A novel solventless delignification of a defatted Picea glehnii wood flour sample was performed using a TiO₂/polyethylene oxide (PEO) photocatalyst system. A cell wall structure of the wood flour was directly observed, showing that its lignin fraction was removed by the photodegradation. The total lignin amount was slightly decreased as compared with that of the pristine sample, and the vanillin formation was confirmed by the ¹H-NMR measurement. The TiO₂ worked as a radical initiator, and simultaneously acid and aldehyde compounds produced by the PEO photolysis did as an accelerator for the solventless delignification. Although the photocatalyst system showed high delignification activity even for a low molecular lignin model, the delignification of the wood flour sample was confined to the surface. It was found that the suppressed delignification behavior was due to crosslinked structure of lignin.     

Recovery of gold by chicken egg shell membrane-conjugated chitosan beads

We have successfully prepared a bead-type adsorbent from two materials with different adsorption characteristics. Heavy metals were removed by greatly swollen egg shell membrane-conjugated chitosan beads. The egg shell membrane accumulated and removed precious metal ions from a dilute aqueous solution with a high affinity in a short contact time. Experiments suggested that chitosan beads could take up gold ions with great capacity and selectivity by conjugation with egg shell membrane. Under certain conditions, the selective removal of gold and copper in a mixture of gold and copper ions by egg shell membrane-conjugated chitosan beads was 100% and 2%, respectively. Egg shell membrane-conjugated chitosan beads can be seen as a promising material to recover gold in wastewater from various industries, such as electroplating.     

Infectious waste management in Japan: a revised regulation and a management process in medical institutions

In Japan, the waste management practice is carried out in accordance with the Waste Disposal Law of 1970. The first rule of infectious waste management was regulated in 1992, and infectious wastes are defined as the waste materials generated in medical institutions as a result of medical care or research which contain pathogens that have the potential to transmit infectious diseases. Revised criteria for infectious waste management were promulgated by the Ministry of Environment in 2004. Infectious waste materials are divided into three categories: the form of waste; the place of waste generation; the kind of infectious diseases. A reduction of infectious waste is expected. We introduce a summary of the revised regulation of infectious waste management in this article.     

Sugar compound products of the periphytic diatom <Emphasis Type="Italic">Navicula ramosissima</Emphasis> induce larval settlement in the barnacle, <Emphasis Type="Italic">Amphibalanus amphitrite</Emphasis>

This study investigated the response of cyprids of the barnacle Amphibalanus amphitrite to 23 strains of laboratory cultured periphytic diatoms isolated from microbial biofilms that formed on glass slides immersed in Tachibana bay, Nagasaki, and those from mass-production tanks in the Fisheries Center of Nagasaki City, Japan. In addition, periphytic diatoms were subjected to various treatments, in order to investigate the nature of the chemical cue in periphytic diatoms. Cyprids of A. amphitrite responded differently to the 23 different periphytic diatom strains and settled in high percentages on Cocconeis sp. and Navicula ramosissima strain A. On the other hand, nine strains of diatoms significantly inhibited settlement. The settlement inducing activity of N. ramosissima strain A increased linearly with diatom density, and its activity was enhanced by culturing the diatom under a bacteria-free condition, suggesting that specific diatom species, i.e., N. ramosissima strain A, may play an important role on larval settlement of the barnacle. Subjecting N. ramosissima strain A biofilm to hydrochloric acid (HCl) and ethanol (EtOH) treatments or heating it at 100°C did not inactivate the film, indicating that the settlement cue was a stable surface bound compound that did not decompose from the above treatments. Moreover, of the various lectins, enzymes, and drugs [H₅IO₆ and sodium dodecyl sulfate or (SDS)] used, only Lentil Agglutinin (LCA) treatment of N. ramosissima strain A biofilm resulted in the reduction its settlement inducing activity. A positive correlation was observed between the settlement inducing activity and the amount of LCA conjugated fluorescein isothiocyanate (FITC-LCA) of N. ramosissima strain A. On the other hand, subjecting biofilms of N. ramosissima strain B, an inactive strain, to various types of treatments resulted in the induction of A. amphitrite larval settlement but LCA treatment also reduced the activity of these treated N. ramosissima strain B biofilms. These findings suggest that a cue containing an LCA-binding sugar chain is present in both A and B strains of N. ramosissima but the large amount of mucous substance covering N. ramosissima strain B biofilm probably makes the sugar chain containing active subunit in strain B unavailable to A. amphitrite cyprids. In conclusion, periphytic diatoms such as N. ramosissima play an important role in larval settlement of the barnacle A. amphitrite. The cue in the diatom was an LCA-binding sugar chain(s) compound that may have similarities to the settlement inducing protein complex (SIPC) from adult shell of the barnacle.     

Evolutionary relationships of deep-sea mussels inferred by mitochondrial DNA sequences

In order to elucidate the evolutionary process of deep-sea Bathymodiolus mussels, we investigated the phylogenetic relationships of 16 species worldwide by analyzing nucleotide sequences of the mitochondrial COI and ND4 genes. Deep-sea mussels were clustered into three groups by basal trichotomous divergence. The first was composed of four species found in Japanese waters and one species from the Gulf of Mexico, which contain methanotrophic endosymbiotic bacteria. The second included nine species distributed in the West and East Pacific, Indian, and Atlantic Oceans. Members of the second group were trichotomously divided into the Indo-West Pacific, Atlantic, and East Pacific subclusters. The Indo-West Pacific subcluster was composed of three very closely related species with mutual genetic distances at the intraspecific level (av. 0.019 in COI and 0.009 in ND4 relative to av. 0.156 in COI and 0.265 in ND4 among Bathymodiolus species other than Cluster A species), suggesting some gene flow among these species. The third consisted of two West Pacific species. Species in the second and third groups contain mainly thioautotrophic endosymbionts, including some species harboring both methanotrophs and thioautotrophs.     

Growth inhibition and formation of morphologically abnormal cells of <Emphasis Type="Italic">Akashiwo sanguinea</Emphasis> (Hirasaka) G. Hansen et Moestrup by cell contact with <Emphasis Type="Italic">Cochlodinium polykrikoides</Emphasis> Margalef

We investigated the growth interaction between Cochlodinium polykrikoides and Akashiwo sanguinea using bi-algal cultures. When cultured together, morphologically abnormal cells of A. sanguinea appeared and the growth of A. sanguinea notably decreased. When C. polykrikoides and A. sanguinea were cultured separately in inner and outer wells separated by a membrane with a pore size of 3 μm, neither species showed suppressed growth and no morphologically abnormal cells of A. sanguinea were observed. Furthermore, filtrates from C. polykrikoides cultures did not affect the cell morphology or the growth of A. sanguinea. When the abnormal cells of A. sanguinea were transferred from bi-algal cultures into fresh medium and cultured as a mono-algal culture, cells recovered their normal morphology and multiplied. Therefore, the growth inhibition and formation of morphologically abnormal cells of A. sanguinea would be induced by constant cell contact with C. polykrikoides.     

Measurement of photosynthetic production of a marine phytoplankton population using a stable 13C isotope

The use of stable isotope of carbon, ¹³C, for the determination of the photosynthetic rate of a marine phytoplankton population was examined. Particular concern was paid to the effects of non-phytoplanktonic organic carbon and the enrichment of inorganic carbon on the estimation of the photosynthetic rate. Photosynthetic rates determined by the ¹³C method showed a remarkable agreement with those determined by the ¹⁴C method. Insitu determinations of photosynthetic rate were made in three different water types: open ocean, coastal and neritic waters, which included oligo- and mesotrophic waters, by using the ¹³C method established.     

Bioaccumulation of mercury in a vestimentiferan worm living in Kagoshima Bay,Japan

The present study reports on the mercury concentrations of the vestimentiferan worm, Lamellibrachia satsuma, (Annelida: Pogonophora) found near hydrothermal vents at a depth of 80-100 m in the northern parts of Kagoshima Bay. The vestimentiferan worms had total mercury concentrations of 238 ng/g in the anterior muscle of the body and 164 ng/g in the posterior trophosome. Methylmercury constituted only 7.6% of total mercury detected anteriorly and 16.3% posteriorly. The mean total mercury concentration in filtrated ambient seawater of the worm habitat was 1.1 ng/l. The worm should accumulate mercury in seawater by a one-step into the anterior and posterior parts as 2.2 x 10(%) and 1.5 x 10(5) times those of the filtered ambient seawater, respectively. The bioaccumulation factor of mercury by the worms with only their respiration would be actually larger than that by other marine animals through food webs. The high bioaccumulation factor of mercury in the worms suggest the following two possibilities: (i) the biological half-life of organomercury in the worm could be exceptionally long; or (ii) the lifetime of vestimentiferan worms examined in the present study could be extremely long. Various metals in one specimen of the worm were analyzed by using ICP-MS, and then gold as well as silver were detected in the worm. Gold was detected for the first time from marine animals.     

Research to develop a predicting system of mammalian subacute toxicity (3) construction of a predictive toxicokinetics model

A new predictive toxicokinetics model was developed to estimate subacute toxicity (target organs, severity, etc.) of non-congeneric industrial chemicals, where the chemical structures and physico-chemical properties are only available. Thus, a physiological pharmacokinetics model, which consists of blood, liver, kidney (these were experimentally found as major toxicological targets), muscle and fat compartments , was established to simulate the chemical concentrations in organs/tissues with pharmacokinetic parameters by means of Runge-Kutta-Gill algorithm. The pliarmacokinetic parameters, i.e. absorption rate, absorption ratio, hepatic extraction ratio of metabolism and renal clearance were calculated by using separately established Quantitative Structure-Pharmacokinetics Relationship equations. The developed predictive model was then applied to simulations of 43 non-congeneric industrial chemicals. The chemical concentrations in organs/tissues after single oral administration were simulated, and their maximum concentrations (Cmax's) and area tinder the concentration-time curves (AUC's) were calculated.Fast Inverse Laplace Transform was newly applied for the purpose of simulation of 28-day repeated dose toxicity.Simulated concentrations of 28 days repeated dose were, however, found to be the same as those of simple repetitions of a single administration per day because of the short half-lives of non-congeneric industrial chemicals.A comparison of subacute toxicity data with Cmax's and AUC's in a single dose scenario suggested that the organs/tissues with relatively high concentrations of tested chemical substances were the most sensitive targets within a chemical.Chemical concentrations in liver, for instance, were correlated with the severity of hepatotoxicity among the chemicals. It was also suggested that to improve and widen the present approach, data of metabolite and reactivity of non-congeneric industrial chemicals to organs/tissues, receptors, etc. should be incorporated into the model.