Real-time reverse transcription PCR analysis of trichloroethylene-regulated toluene dioxygenase expression in Pseudomonas putida F1

Toluene dioxygenase (tod) is a multicomponent enzyme system in Pseudomonas putida F1. Tod can mediate the degradation of Trichloroethylene (TCE), a widespread pollutant. In this study, we try to explore the TCE-regulated tod expression by using real-time qRT-PCR. The minimal culture media were supplemented with glucose, toluene, or a mixture of glucose/toluene respectively as carbon and energy sources. The TCE was injected into each medium after a 12-hour incubation period. The TCE injection severely affected bacterial growth when cultured with toluene or toluene/glucose mixtures. The cell density dropped 61 % for bacteria growing in toluene and 36 % for bacteria in the glucose/toluene mixture after TCE injection, but the TCE treatment had little effect on bacteria supplied with glucose alone. The decrease in cell number was caused by the cytotoxicity of the TCE metabolized by tod. The results from the real-time qRT-PCR revealed that TCE was capable of inducing tod expression in a toluene-dependent manner and that the tod expression level increased 50 times in toluene and 3 times in the toluene/glucose mixture after 6 hours of TCE treatment. Furthermore, validation of the rpoD gene as a reference gene for P. putida F1 was performed in this study, providing a valuable foundation for future studies to use real-time qRT-PCR in the analysis of the P. putida F1 strain.     

Production characteristics of lipopeptide antibiotics in biofilm fermentation of Bacillus subtilis

In biofilm fermentation, from the very early moments, surfactin was produced along with the biofilm development in the lipopeptide antibiotic production medium by using Bacillus subtilis. However, almost no iturin A was produced in its first 24 hours of cultivation and the production of iturin A began much later. Volumes of the nutrient medium and available surface area of the biofilm reactors were found to be important with the relative production of these two antibiotics. Production of iturin A was increased from 12 mg to about 50 mg per reactor when the culture size was increased from 5 mL to 20 mL, as the depth of the medium was increased. The production level was saturated thereafter with larger volumes. On the other hand, surfactin production was remained similar, which was about 10 mg per reactor, from all the 5 mL to 80 mL of biofilm culture. Optimized temperature for iturin A and surfactin production was observed at 25 and 37°C, respectively. In the biofilm fermentation, production of surfactin was increased when the incubation temperature was increased within the temperature range of 25 to 37°C, on the other hand, iturin A production was gradually decreased with the increase of the incubation temperature.     

Spatial variability of nitrous oxide emissions and their soil-related determining factors in an agricultural field

To evaluate spatial variability of nitrous oxide (N2O) emissions and to elucidate their determining factors on a field-scale basis, N2O fluxes and various soil properties were evaluated in a 100- x 100-m onion (Allium cepa L.) field. Nitrous oxide fluxes were determined by a closed chamber method from the one-hundred 10- x 10-m plots. Physical (e.g., bulk density and water content), chemical (e.g., total N and pH), and biological (e.g., microbial biomass C and N) properties were determined from surface soil samples (0-0.1 m) of each plot. Geostatistical analysis was performed to examine spatial variability of both N2O fluxes and soil properties. Multivariate analysis was also conducted to elucidate relationships between soil properties and observed fluxes. Nitrous oxide fluxes were highly variable (average 331 microg N m(-2) h(-1), CV 217%) and were log-normally distributed. Log-transformed N2O fluxes had moderate spatial dependence with a range of >75 m. High N2O fluxes were observed at sites with relatively low elevation. Multivariate analysis indicated that an organic matter factor and a pH factor of the principal component analysis were the main soil-related determining factors of log-transformed N2O fluxes. By combining multivariate analysis with geostatistics, a map of predicted N2O fluxes closely matched the spatial pattern of measured fluxes. The regression equation based on the soil properties explained 56% of the spatially structured variation of the log-transformed N2O fluxes. Site-specific management to regulate organic matter content and water status of a soil could be a promising means of reducing N2O emissions from agricultural fields.     

SPATIAL AND TEMPORAL DYNAMICS OF WOOD IN HEADWATER STREAMS OF THE PACIFIC NORTHWEST1

This paper synthesizes information on the spatial and temporal dynamics of wood in small streams in the Pacific Northwest region of North America. The literature on this topic is somewhat confused due to a lack of an accepted definition of what constitutes “small” streams and what is the relative size of woody debris contained within the channel. This paper presents a matrix that defines woody debris relative to channel size and then discusses the components of a wood budget. Headwater streams are in close proximity to wood sources and, in steeplands, are often tightly constrained by steep hillslopes. Special consideration is given to ecosystem characteristics and to management practices that affect the wood dynamics in this context. Knowledge gaps and uncertainties that can be used to guide future research are identified. Very little is currently known about the role of mass wasting in wood recruitment and storage relative to other processes, such as bank erosion and mortality, in larger streams. Further, very little work has addressed the relative importance of different wood depletion processes, especially those associated with wood transport. The effect of other ecosystem variables on wood dynamics locally across a watershed (from valley bottom to mountaintop) and regionally across the landscape (from maritime to continental climates) is not addressed. Finally, the scientific community has only begun to deal with the effects of management practices on wood quantity, structure, and movement in small streams.     

Factors associated with prehospital death among traffic accident patients in Osaka City,Japan: A population-based study

Objective: Although it is important to assess the factors associated with traffic accident fatalities to decrease them as a matter of public health, such factors have not been fully identified.

Methods: Using a large-scale data set of ambulance records in Osaka City, Japan, we retrospectively analyzed all traffic accident patients transported to hospitals by emergency medical service personnel from 2013 to 2014. In this study, prehospital death was defined as that occurring at the scene or in the emergency department immediately after hospital arrival. We assessed prehospital factors associated with prehospital death due to traffic accidents by logistic regression models.

Results: This study enrolled 28,903 emergency patients involved in traffic accidents, of whom 68 died prehospital. In a multivariate model, elderly patients aged ≥75 years (adjusted odds ratio [AOR] = 4.34; 95% confidence interval [CI], 2.29–8.23), nighttime (AOR = 2.75; 95% CI, 1.65–4.70), and type of injured person compared to bicyclists such as pedestrians (AOR = 9.58; 95% CI, 5.07–17.99), motorcyclists (AOR = 2.75; 95% CI, 1.21–6.24), and car occupants (AOR = 2.98; 95% CI, 1.39–6.40) were significantly associated with prehospital death due to traffic accidents. In addition, the AOR for automobile versus nonautomobile as the collision opponent was 4.76 (95% CI, 2.30–9.88).

Conclusions: In this population, the factors associated with prehospital death due to traffic accidents were elderly people, nighttime, and pedestrian as the type of patient. The proportion of prehospital deaths due to traffic accidents was also high when the collision component was an automobile.     

Optimizing nutrient supply in a rotatory-switching biofilter for toluene vapor treatment

The influence of nutrient conditions on the degradation of toluene vapor in a rotatory-switching biofilter (RSB) was investigated. The biofilter consists of four segments connected in series, each with a packing layer made of polyvinyl formal. The influent airstreams including toluene vapors were passed through segments 1-3 as up-flow with a toluene concentration of 0.9-1.2 g m(-3) and with an empty-bed retention time of 26-52 sec. Nutrient solutions were fed to all packed segments once a day by means of immersion. The nutrient solution was used repeatedly and replenished by the addition of (NH4)2SO4. The result at 155 days showed nitrogen depletion was particularly obvious and the lack of nitrogen affected toluene removal. By adding 161 g of nitrogen solution per volumetric cubic meter of reactor, toluene removal efficiency was immediately increased to greater than 99%. With long-term biofilter operation, 21%-32% of ammonium was utilized for nitrification because of the growth of nitrifying bacteria such as Nitrosomonas sp. Based on the carbon-nitrogen balance, the daily nitrogen demand for toluene removal was estimated 2.1 g day(-1) at a toluene load of 70 g m(-3) hr(-1).     

Tritium concentrations in the atmospheric environment at Rokkasho, Japan before the final testing of the spent nuclear fuel reprocessing plant

This study aimed at obtaining background tritium concentrations in precipitation and air at Rokkasho where the first commercial spent nuclear fuel reprocessing plant in Japan has been under construction. Tritium concentration in monthly precipitation during fiscal years 2001-2005 had a seasonal variation pattern which was high in spring and low in summer. The tritium concentration was higher than that observed at Chiba City as a whole. The seasonal peak concentration at Rokkasho was generally higher than that at Chiba City, while the baseline concentrations of both were similar. The reason for the difference may be the effect of air mass from the Asian continent which is considered to have high tritium concentration. Atmospheric tritium was operationally separated into HTO, HT and hydrocarbon (CH₃T) fractions, and the samples collected every 3 d-14 d during fiscal year 2005 were analyzed for these fractions. The HTO concentration as radioactivity in water correlated well with that in the precipitation samples. The HT concentration was the highest among the chemical forms analyzed, followed by the HTO and CH₃T concentrations. The HT and CH₃T concentrations did not have clear seasonal variation patterns. The HT concentration followed the decline previously reported by Mason and Östlund with an apparent half-life of 4.8 y. The apparent and environmental half-lives of CH₃T were estimated as 9.2 y and 36.5 y, respectively, by combining the present data with literature data. The Intergovernmental Panel on Climate Change used the atmospheric lifetime of 12 y for CH₄ to estimate global warming in its 2007 report. The longer environmental half-life of CH₃T suggested its supply from other sources than past nuclear weapon testing in the atmosphere.     

Mass spectrometric study of secondary organic aerosol formed from the photo-oxidation of aromatic hydrocarbons

From measurements by an Aerodyne Aerosol Mass Spectrometer (AMS), secondary organic aerosol (SOA) formed in laboratory chambers is believed to be less oxidized than well-oxidized ambient organic aerosol (OA). However, the mass spectrum of SOA formed from the photo-oxidation of aromatic hydrocarbons has not been sufficiently studied by using AMS though these reactions are potential sources of urban SOA. In this study, we studied SOA formed from the photo-oxidation of seven aromatic hydrocarbons by using Time-of-Flight AMS. Strong mass signals from SOA were found at m/z 43 (m43) and 44 (m44) in all the experiments. The m44 to total organic aerosol mass ratio (m44/OA) increased with irradiation time. For example, the m44/OA ratio increased from 10.6% to 13.3% during irradiation for 11 h in an experiment with toluene. The average m44/OA ratios were determined to be 5.8–17.1% for all the experiments. The m44/OA decreased and the m43/OA increased with increasing number of alkyl substituents of precursor aromatic hydrocarbons. This is because low-reactive ketones are preferentially produced rather than aldehydes with increasing number of alkyl substituents. The m44/OA ratios of the benzene and monoalkylbenzene oxidation were 12.2–17.1% and were close to those of well-oxidized ambient OA. These findings are consistent with the hypothesis that the photo-oxidation of aromatic hydrocarbons is a potential source of urban SOA. In addition to oxygenated organic compounds, organic nitrogen oxides were also shown to be present in SOA by high-resolution mass spectra.     

Congener-specific analysis of non-dioxin-like polychlorinated biphenyls in blood collected from 195 pregnant women in Sapporo City, Japan

We conducted a congener-specific analysis of non-dioxin-like polychlorinated biphenyls (non-dioxin-like PCBs) in blood collected between July 2002 and July 2004 from 195 pregnant women living in Sapporo City of Hokkaido Prefecture, Japan. The present study is one of the few studies in which full congener concentrations of non-dioxin-like PCBs have been measured in the blood of pregnant women. Of the 195 pregnant women, 101 were primipara (mean: 28.8 years, median: 28.0 years) and 94 were multipara (mean: 32.3 years, median: 33.0 years). Among the 197 non-dioxin-like PCB congeners, 58 congeners were identified in the blood of pregnant women. The arithmetic mean total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers in Sapporo City were 42.2-329.3 (mean: 114.5, median: 98.6) and 31.5-258.0 (mean: 100.3, median: 91.4)ngg(-1)lipid, respectively. The results show that the contamination of non-dioxin-like PCBs in the blood of women has decreased compared to past levels in other domestic areas, in which the subject age was similar to that in this study. The results of the present study indicate that current levels of non-dioxin-like PCBs in the blood of Japanese women and can be used as baseline data for future temporal trends. The sums of the ratios of the concentrations of hexaCBs and heptaCBs to the total concentrations of 58 non-dioxin-like PCB congeners in the blood of primiparous and multiparous mothers were 78.5% and 77.7%, respectively. The hexaCBs ratios in the blood of primiparous and multiparous mothers were 45.4% and 44.7%, respectively. HexaCB-153 among hexaCBs congeners, the most abundant congener in the blood of primiparous and multiparous mothers, contributed approximately 22.0% and 21.8% to the total concentrations of 58 non-dioxin-like PCBs congeners that were measured in the blood, respectively. Among the non-dioxin-like PCB congeners measured in the present study, hexaCB-138, heptaCB-170, heptaCB-180, and heptaCB-182/heptaCB-187 also showed high ratios to total concentrations of 58 non-dioxin-like PCB congeners detected in the blood of primiparous and multiparous mothers. With regard to the relationship between the total concentrations of 58 non-dioxin-like PCB congeners in maternal blood and the number of deliveries or the age of primiparous and multifarious mothers, the total levels of these PCB congeners tended to decreases with increases in the number of deliveries and significantly increased with increasing maternal age in both groups. Furthermore, significant correlations were observed between the total concentrations of these PCB congeners in blood and the age of primiparae and multiparae. The concentrations of hexaCB-153 in the blood of primiparous and multiparous mothers showed a close correlation to the total concentrations of these PCBs, suggesting that hexaCB-153 could be an indicator of total concentrations of non-dioxin-like PCB congeners in the blood of pregnant women.