Genetic engineering of cyanobacteria to enhance biohydrogen production from sunlight and water

To mitigate global warming caused by burning fossil fuels, a renewable energy source available in large quantity is urgently required. We are proposing large-scale photobiological H(2) production by mariculture-raised cyanobacteria where the microbes capture part of the huge amount of solar energy received on earth's surface and use water as the source of electrons to reduce protons. The H(2) production system is based on photosynthetic and nitrogenase activities of cyanobacteria, using uptake hydrogenase mutants that can accumulate H(2) for extended periods even in the presence of evolved O(2). This review summarizes our efforts to improve the rate of photobiological H(2) production through genetic engineering. The challenges yet to be overcome to further increase the conversion efficiency of solar energy to H(2) also are discussed.     

Studies on automated survey system of environmental chemicals by gas chromatography-mass spectrometry-computer II. Three dimensional mass chromatography

A three dimensional mass chromatography (TDMC), which is the extended method of mass chromatography, has been developed for the analysis of environmental chemicals. A considerable performance was suggested by the combination of TDMC to gas chromatography-mass spectrometry-computer system.     

The sensitivity of carbon sequestration to harvesting and climate conditions in a temperate cypress forest: Observations and modeling

The role of disturbance and climate factors in determining the forest carbon balance was investigated at a Japanese cypress forest in central Japan with eddy flux measurements, tree-ring analyses, and a terrestrial biosphere model. The forest was established as a plantation after intermittent harvesting and replanting between 1959 and 1977, and acted as a strong carbon sink of approximately 500 g C m⁻² year⁻¹ for the measurement years between 2001 and 2007. A terrestrial biosphere model, BIOME-BGC, was validated using the eddy flux data at daily to interannual timescales, and the tree-ring width data at interannual to decadal timescales. According to the model simulation, during the observation period 270 ± 55 g C m⁻² year⁻¹ was additionally sequestered due to the indirect effects of the harvesting and planting, whereas the increase of CO₂ concentration and the change in climate increased the sink of 110 ± 40 and 30 ± 80 g C m⁻² year⁻¹, respectively. The model simulation shows that the forest is now recovering from harvesting, and that harvesting is a more important determinant of the current carbon sink than either interannual climate anomalies or increased atmospheric CO₂ concentration. We found that harvesting with long rotation length could be effective management activity in order to increase carbon sequestration, if the harvested timber is converted into products with long lifecycles.     

Technical Procedures for CDM Project Design

The success of CDM depends on active participation of public and private entities. In particular, participation of wide range of private companies is an important factor for the success. In order to promote the participation of private companies in the CDM project activities as project participants, the authors clarify the steps and technical issues involved in the CDM project design procedures in a step-by-step approach. The steps consist of outlining the project plans, identifying project impacts, defining a project boundary, estimating GHG emissions reduction/enhancement of removals, documenting the results of estimation, and designing of monitoring plans. The authors also propose guidance for project participants, especially for those not familiar with the CDM, which provides plain explanation of major technical issues. In order to further develop a complete guideline, it is necessary to integrate the outputs of the ongoing international initiatives concerning technical issues of CDM into the stepwise approach proposed in this paper. This revised version was published online in August 2006 with corrections to the Cover Date.     

A hierarchical analysis of terrestrial ecosystem model Biome-BGC: Equilibrium analysis and model calibration

The increasing complexity of ecosystem models represents a major difficulty in tuning model parameters and analyzing simulated results. To address this problem, this study develops a hierarchical scheme that simplifies the Biome-BGC model into three functionally cascaded tiers and analyzes them sequentially. The first-tier model focuses on leaf-level ecophysiological processes; it simulates evapotranspiration and photosynthesis with prescribed leaf area index (LAI). The restriction on LAI is then lifted in the following two model tiers, which analyze how carbon and nitrogen is cycled at the whole-plant level (the second tier) and in all litter/soil pools (the third tier) to dynamically support the prescribed canopy. In particular, this study analyzes the steady state of these two model tiers by a set of equilibrium equations that are derived from Biome-BGC algorithms and are based on the principle of mass balance. Instead of spinning-up the model for thousands of climate years, these equations are able to estimate carbon/nitrogen stocks and fluxes of the target (steady-state) ecosystem directly from the results obtained by the first-tier model. The model hierarchy is examined with model experiments at four AmeriFlux sites. The results indicate that the proposed scheme can effectively calibrate Biome-BGC to simulate observed fluxes of evapotranspiration and photosynthesis; and the carbon/nitrogen stocks estimated by the equilibrium analysis approach are highly consistent with the results of model simulations. Therefore, the scheme developed in this study may serve as a practical guide to calibrate/analyze Biome-BGC; it also provides an efficient way to solve the problem of model spin-up, especially for applications over large regions. The same methodology may help analyze other similar ecosystem models as well.     

Metabolism of benzo(a)pyrene in rat by oral administration

Orally administered ³H-benzo(a)pyrene (BP) was concentrated in liver, kidney and lung of rat. Liver contained BP-diols, BP-quinones and 3-hydroxy-BP, and extremely high amounts of BP-quinones and unmetabolized BP were found in lung until after 7 hr of administration. In kidney, BP-quinones and BP-diols were major metabolites, but not BP or 3-hydroxy-BP. Low level of metabolites as conjugates with glucuronate and more polar compounds were also detected in kidney. These results suggested that an orally administered BP was metabolized to BP-diols and 3-hydroxy-BP mainly in liver, to BP-quinones mainly in lung, and to BP-diols and glucuronides or more polar compounds mainly in kidney.     

Studies on the indicator for heavy metal contamination in environments (1) Heavy metal contents of hair,nail and moustache

Heavy metal (Hg, Pb, Cd, Cu, Ni, Fe, Zn, and Mn) contents of the samples from 10 males were followed throughout a year. The values were characteristic of the individuals, and some correlationships between the contents of different metals were shown.     

Metabolism of 3-hydroxybenzo (a) pyrene in rat,isolated hepatocytes and kidney

After intravenous injection of 3-hydroxybenzo (a) pyrene into rat, benzo (a) pyrene-diols were detected in urine, and $\text{in vitro}$ experiment using isolated hepatocytes and sliced kidney also indicated the metabolism of 3-hydroxybenzo (a) pyrene to diol derivatives. THese results suggested the presence of unknown metabolic pathway of benzo (a) pyrene-phenols such as 3-hydroxybenzo (a) pyrene to diol derivatives both $\text{in vivo}$ and $\text{in vitro}$.     

Genetic Engineering of Cyanobacteria to Enhance Biohydrogen Production from Sunlight and Water

To mitigate global warming caused by burning fossil fuels, a renewable energy source available in large quantity is urgently required. We are proposing large-scale photobiological H₂ production by mariculture-raised cyanobacteria where the microbes capture part of the huge amount of solar energy received on earth’s surface and use water as the source of electrons to reduce protons. The H₂ production system is based on photosynthetic and nitrogenase activities of cyanobacteria, using uptake hydrogenase mutants that can accumulate H₂ for extended periods even in the presence of evolved O₂. This review summarizes our efforts to improve the rate of photobiological H₂ production through genetic engineering. The challenges yet to be overcome to further increase the conversion efficiency of solar energy to H₂ also are discussed.