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.     

Energy reduction of a submerged membrane bioreactor using a polytetrafluoroethylene (PTFE) hollow-fiber membrane

The fiber length and packing density of the PTFE membrane element were increased. The MBR was stably operated under an SAD^m of 0.13 m³·m^-2·hr^-1. Specific energy consumption was estimated to be less than 0.4 kWh·m^-3. In this study, we modified a polytetrafluoroethylene (PTFE) hollow-fiber membrane element used for submerged membrane bioreactors (MBRs) to reduce the energy consumption during MBR processes. The high mechanical strength of the PTFE membrane made it possible to increase the effective length of the membrane fiber from 2 to 3 m. In addition, the packing density was increased by 20% by optimizing the membrane element configuration. These modifications improve the efficiency of membrane cleaning associated with aeration. The target of specific energy consumption was less than 0.4 kWh·m^-3 in this study. The continuous operation of a pilot MBR treating real municipal wastewater revealed that the MBR utilizing the modified membrane element can be stably operated under a specific air demand per membrane surface area (SAD_m) of 0.13 m³·m^-2·hr^-1 when the daily-averaged membrane fluxes for the constant flow rate and flow rate fluctuating modes of operation were set to 0.6 and 0.5 m³·m^-2·d^-1, respectively. The specific energy consumption under these operating conditions was estimated to be less than 0.37 kWh·m^-3. These results strongly suggest that operating an MBR equipped with the modified membrane element with a specific energy consumption of less than 0.4 kWh·m^-3 is highly possible.     

Larval metamorphosis of the mussel <Emphasis Type="Italic">Mytilus galloprovincialis</Emphasis> in response to <Emphasis Type="Italic">Alteromonas</Emphasis> sp. 1: evidence for two chemical cues?

Bacterial isolates from multi-species biofilms were identified by 16S rDNA gene sequences and investigated for their inductive effects as monospecific biofilms on larval metamorphosis of Mytilus galloprovincialis. Alteromonas sp. 1 biofilm was found to have inductive activity, which increased with increasing cell density. The cue(s) of Alteromonas sp. 1 biofilm responsible for inducing larval metamorphosis was further investigated. Treatment of the biofilm with formalin, ethanol, heat or ultraviolet irradiation resulted in a significant reduction in the inductive activity of Alteromonas sp. 1, and the crude extract of surface-bound products of the biofilm showed no activity. These results indicated that if the cue was a surface-bound chemical cue, it was unstable, or susceptible to the treatments or the extraction process. On the other hand, the inductive activity of treated biofilms had a linear regression to the cell survival of bacteria, indicating a metabolically active biofilm was a requirement for larval metamorphosis. Conditioned water of the biofilm did not induce larvae to metamorphose. However, larval crawling behavior in the conditioned water was the same as that in the biofilm prior to larval metamorphosis, and significantly different to larval behavior in seawater. This indicated that a potential or partial waterborne cue existed, but remained inactive when alone. A synergistic effect of the conditioned water with formalin-fixed Alteromonas sp. 1 biofilm resulted in a significant increase in larval metamorphosis. Heat treatment and fractionation of the conditioned water demonstrated that the waterborne cue was heat-stable and <3,000 Da in molecular weight. Platinum-coating, Lentil Lectin and Wheat Germ Agglutinin treatments of the formalin-fixed biofilm significantly reduced its synergistic effect with the conditioned water, suggesting that a surface-bound cue was present on the biofilm and that the cue might be associated with the bacterial exopolysaccharide or glycoprotein. Evidence presented here suggests that two chemical cues derived from bacteria act synergistically on larval metamorphosis of Mytilus galloprovincialis.     

Light-stress avoidance mechanisms in a Sphagnum-dominated wet coastal Arctic tundra ecosystem in Alaska

The Arctic experiences a high-radiation environment in the summer with 24-hour daylight for more than two months. Damage to plants and ecosystem metabolism can be muted by overcast conditions common in much of the Arctic. However, with climate change, extreme dry years and clearer skies could lead to the risk of increased photoxidation and photoinhibition in Arctic primary producers. Mosses, which often exceed the NPP of vascular plants in Arctic areas, are often understudied. As a result, the effect of specific environmental factors, including light, on these growth forms is poorly understood. Here, we investigated net ecosystem exchange (NEE) at the ecosystem scale, net Sphagnum CO2 exchange (NSE), and photoinhibition to better understand the impact of light on carbon exchange from a moss-dominated coastal tundra ecosystem during the summer season 2006. Sphagnum photosynthesis showed photoinhibition early in the season coupled with low ecosystem NEE. However, later in the season, Sphagnum maintained a significant CO2 uptake, probably for the development of subsurface moss layers protected from strong radiation. We suggest that the compact canopy structure of Sphagnum reduces light penetration to the subsurface layers of the moss mat and thereby protects the active photosynthetic tissues from damage. This stress avoidance mechanism allowed Sphagnum to constitute a significant percentage (up to 60%) of the ecosystem net daytime CO2 uptake at the end of the growing season despite the high levels of radiation experienced.     

Where will large amounts of materials accumulated within the economy go? – A material flow analysis of construction minerals for Japan

For all countries analyzed so far, Material Flow Analysis/Accounting (MFA) studies indicate that the overall stock of materials within the economy is growing. Most are construction minerals such as asphalt, cement, sand and gravel, crushed stone, and other aggregates. In the analyses described in this paper, flows and stocks of construction minerals were estimated for Japan from the past to the future to elucidate: (1) the mechanisms by which construction minerals become waste, and (2) the future supply of and demand for recycled crushed stone. The following conclusions were drawn: (1) The amounts of waste construction minerals generated have been and will be at much lower levels than the domestic demand for construction minerals. These differences might indicate consistent growth of the stock of construction minerals, which will become waste in the future. However, certain amounts of materials that we account for as stock can be interpreted already in the environment as dead stock or dissipated waste; such materials can be called "missing stock" or "dissipated stock". Capturing that missing or dissipated stock is very important because it provides information that clarifies the environmental impacts and loss of resources that these materials cause; it allows estimation of appropriate future waste generation. (2) The amount of construction minerals that are recognized as waste was estimated to increase in the future. An imbalance in the supply of and demand for recycled crushed stone will likely occur in the near future if an expected decline in future road construction is considered.     

Modified clean-up for PBDD,PBDF and PBDE with an active carbon column--its application to sediments

A clean-up method for polybrominated dibenzo-p-dioxins (PBDDs), dibenzofurans (PBDFs) and diphenyl ethers (PBDEs) was modified using combinations of multi-layered silica gel, Florisil and active carbon columns. By using active carbon column chromatography in the final procedure, PBDEs were well separated from PBDD/Fs in an elution test with reference standards. We report the application of this method to sediment samples taken from industrialized areas in Japan. These sediments contained PBDEs ranging in concentration from 13 to 2394 pg/g, dry wt. PBDEs did not interfere with the quantification of PBDD/Fs. In addition, PBDEs found in the PBDD/F fraction did not interfere with the identification of PBDFs using the HRGC/HRMS separation method. Some 2,3,7,8-tetra- to hexabrominated dioxins and furans were also detected in the sediment samples.     

Polychlorinated biphenyl (118) activates osteoclasts and induces bone resorption in goldfish

To analyze the effect of polychlorinated biphenyl (PCB) 118 on fish bone metabolism, we examined osteoclastic and osteoblastic activities, as well as plasma calcium levels, in the scales of PCB (118)-injected goldfish. In addition, effect of PCB (118) on osteoclasts and osteoblasts was investigated in vitro. Immature goldfish, in which the endogenous effects of sex steroids are negligible, were used. PCB (118) was solubilized in dimethyl sulfoxide at a concentration of 10 ppm. At 1 and 2 days after PCB (118) injection (100 ng/g body weight), both osteoclastic and osteoblastic activities, and plasma calcium levels were measured. In an in vitro study, then, both osteoclastic and osteoblastic activities as well as each marker mRNA expression were examined. At 2 days, scale osteoclastic activity in PCB (118)-injected goldfish increased significantly, while osteoblastic activity did not change significantly. Corresponding to osteoclastic activity, plasma calcium levels increased significantly at 2 days after PCB (118) administration. Osteoclastic activation also occurred in the marker enzyme activities and mRNA expressions in vitro. Thus, we conclude that PCB (118) disrupts bone metabolism in goldfish both in vivo and in vitro experiments.     

The induction of larval settlement and metamorphosis of two sea urchins,Pseudocentrotus depressus and Anthocidaris crassispina,by free fatty acids extracted from the coralline red alga Corallina pilulifera

Lipophilic inducers of larval settlement and metamorphosis of Pseudocentrotus depressus and Anthocidaris crassispina, two commercially important sea urchin species in Japan, were isolated from the foliose coralline red alga Corallina pilulifera (collected in 1990 near Saga, Japan) and identified. Larval assays of the fractions obtained by silica gel column chromatography of the total lipids showed that non-polar groups of lipids were effective at inducing larval settlement and metamorphosis. The effective fractions were further subjected to gel filtration (Sephadex LH-20) and also to silica gel column chromatography, and the effective components isolated as single spots by thin-layer chromatography. The components at a concentration of ca. 0.4 mg paper^-1 (sample was adsorbed on a paper with 20 cm²) induced high rates of larval settlement of both P. depressus and A. crassispina. Chemical analyses of the components revealed a mixture of free fatty acids (FFAs), dominated by eicosapentaenoic acid (20:5, 41 to 50%), palmitic acid (16:0, 11 to 17%), arachidonic acid (20:4, 9 to 15%), and palmitoleic acid (16:1, 4 to 5%). In assays with the four standard FFAs, only 20:4 and 20:5 induced larval settlement and metamorphosis of the two species, while 16:0 and 16:1 were ineffective. The larvae underwent significant rates of settlement and metamorphosis in response to the two former FFAs at levels as low as 0.18 mg paper^-1. Amongst the free fatty acid components of the alga, 20:5 was isolated as the chemical inducer of larval settlement and metamorphosis of the sea urchins in the laboratory.     

Metal and metalloid contamination in roadside soil and wild rats around a Pb-Zn mine in Kabwe, Zambia

Metal (Cr, Co, Cu, Zn, Cd, Pb, Ni) and metalloid (As) accumulation was studied in roadside soil and wild rat (Rattus sp.) samples from near a Pb-Zn mine (Kabwe, Zambia) and the capital city of Zambia (Lusaka). The concentrations of the seven metals and As in the soil samples and Pb in the rat tissue samples were quantified using atomic absorption spectroscopy. The concentrations of Pb, Zn, Cu, Cd, and As in Kabwe soil were much higher than benchmark values. Geographic Information System analysis indicated the source of metal pollution was mining and smelting activity. Interestingly, the area south of the mine was more highly contaminated even though the prevailing wind flow was westward. Wild rats from Kabwe had much higher tissue concentrations of Pb than those from Lusaka. Their body weight and renal Pb levels were negatively correlated, which suggests that mining activity might affect terrestrial animals in Kabwe.     

Characterization of Photovoltaic Performance of the Dye-Sensitized Solar Cell with a Novel Ruthenium Complex Having a Bisdemethoxycurcumin as a Ligand

The first example of a ruthenium sensitizer (TUS-22) having a natural dye, bisdemethoxycurcumin, as a ligand has been synthesized. The dye-sensitized solar cell based on this novel dye showed 5.8% conversion efficiency under AM 1.5 (100 mW/cm²) irradiation.