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We herein describe a novel washing-free electrochemical strategy for target DNA detection by utilizing the peroxidase mimicking DNAzyme. The DNAzymeincorporated DNA probes, the key components of this strategy, are designed to be not able to form G-quadruplex structure in the initial state such that the peroxidase mimicking activity of DNAzyme is kept suppressed. The DNAzyme sequences, however, would be converted to the catalytically active G-quadruplex structure by the presence of target DNA, whose peroxidase mimicking activity then promote the precipitation reaction of 4-chloronaphthol (4-CN) on the electrode. Due to the precipitates produced on the electrode surface, the electrochemical reaction between the redox materials and electrode surface is inhibited, consequently leading to a significant increase of the impedance signal. Based on this novel electrochemical design principle, we successfully detected the target DNA from sexually transmitted disease (STD) pathogens such as Chlamydia trachomatis, Trichomonas vaginalis, and Herpes simplex virus type 2 in real patient samples, verifying its practical diagnostic capability in the clinical applications.

Forest decline due to atmospheric pollution is a consequence of long-term chronic exposure, and thus chemical proxies that are sensitive to the pollution are helpful in estimating the impact of atmospheric pollution on forest health. In this study, we explored changes in the isotopic and elemental compositions of needles of red pine (Pinus densiflora) with varying precipitation pH and concentrations of NO2 and SO2 across 18 cities to identify isotopic and chemical signatures that are sensitive to acid deposition. The cities had different intensity of traffic and industrial activities, and thus were expected to have varying levels of atmospheric pollution. The pine needles were analyzed for carbon (δ13C) and nitrogen (δ15N) isotope ratios, N concentrations, C-to-N ratio (C/N), and calcium-to-aluminum ratio (Ca/Al). Analysis of variance, simple linear correlation, and redundancy analysis were used to investigate the variations in foliar chemistry with atmospheric variables. Neither NO2 nor SO2 concentration was correlated with foliar δ13C, δ15N, N concentration, and C/N; whereas precipitation pH was correlated with the foliar parameters, suggesting that foliar chemistry is more sensitive to total acidifying materials than to individual pollutant. The foliar δ13C decreased with lowered precipitation pH, reflecting the increased 13C-depleted CO2 that was co-emitted with acidifying materials from fossil fuel combustion. Foliar δ15N decreased and foliar N concentration increased with lowered precipitation pH, indicating tree uptake of 15N-depleted N from acid deposition. Accordingly, the C/N ratio also decreased with lowered precipitation pH. However, there was no relationship between foliar Ca/Al and precipitation pH; rather. Our result suggests that δ13C, δ15N, N concentration, and C/N of pine needle samples are associated with the level of precipitation pH and thus pine needles could be used as bio-indicators of the impacts of total acidifying pollutants on forest.

The effects of increased nitrogen (N) availability through atmospheric deposition on the quantity and quality of tree leaf litter have been widely reported. However, such N effects under co-elevated CO2 concentration ([CO2]) and air temperature (Tair) have not been investigated. In this study, changes in biomass and chemistry of litter of Pinus densiflora S. et Z. (pine) and Quercus variabilis Blume (oak) saplings with two levels of each N × [CO2] × Tair were investigated for two growing seasons. The levels of N, [CO2], and Tair were 2 and 6-fold of ambient N deposition, ambient and ambient + 285 ppmv, and ambient and ambient + 2.2 °C, respectively, on average across the two seasons. The concentrations of N, minerals, and carbon (C) compounds such as non-structural carbohydrate (NSC) and lignin as well as stoichiometry such as the ratio of C to N (C/N) and lignin to N (lignin/N) of litter were analyzed to determine litter chemistry. In addition, the legacy effect of changed chemistry on microbial decomposability of the litters were also assessed by measuring CO2 emission in a 60-day lab incubation experiment. The effect of high N addition on increasing litter production was consistent regardless of [CO2] and Tair for oak; however, for pine, N-induced increases in litter production were negated under elevated [CO2] and/or Tair, probably due to efficient uptake and use of N by pine under elevated [CO2] as well as lowered N demand via warming-induced stress under elevated Tair. High N-induced decreases in C/N and lignin/N was consistent across [CO2]-Tair combination for both species though other chemical components such as NSC and minerals including phosphorous, calcium, aluminum, and manganese varied inconsistently. The CO2 emission from the soils amended with litters of different chemistry was not correlated with litter chemistry, suggesting that changed litter chemistry under different N level × [CO2] × Tair may not affect litter decomposability in the soils. This study enlarges our understanding of the effect of increased N availability on litter quantity, chemical composition, and microbial decomposability under different [CO2] and Tair. However, a study with mature trees in a natural forest stand should further improve our understanding.

To better predict forest productivity under rising atmospheric CO 2 concentration ([CO 2 ]), it is critical to understand how intrinsic water-use efficiency (WUE i ) and its relationship with tree growth are affected by the concomitant changes in environmental conditions such as precipitation, temperature, and air pollution that either enhance or undermine any potential CO 2 fertilization effect. We investigated changes in δ 13 C and WUE i in annual rings and basal area increment (BAI) of Pinus densiflora (from 1968 to 2007) and Quercus variabilis (from 1970 to 2007) trees in relation to precipitation, temperature, and air pollution in a humid temperate forest. The WUE i of P. densiflora increased by 39.9%, whereas that of Q. variabilis did not change over time in the study period. The WUE i was not affected by precipitation for both species but increased ( P P. densiflora and with SO 2 emissions for both species. Multiple regression models suggested that the effect of [CO 2 ] on tree growth was much higher than temperature; however, for the period (1998 to 2007) when SO 2 emissions data were available, SO 2 emission was the driver of changes in BAI and WUE i , and temperature effects became stronger than [CO 2 ]. Overall, BAI and WUE i were positively ( P P. densiflora , but not for Q. variabilis . We conclude that temperature and air pollution rather than precipitation were key determinants of WUE i at the study site and that the two species had contrasting responses to environmental changes.

Historical growth response of Quercus variabilis, which is the most important deciduous timber species in Korea, was investigated using the width and C isotope ratio (13C/12C denoted as δ13C) of the annual ring from 1975 to 2007. Tree disks were collected from three Q. variabilis trees with different growth statuses from a site in the Mt. Naejang area, and analyzed for annual ring width and δ13C. Basal area increment (BAI) of the annual ring was calculated from the width data, and carbon isotope discrimination (Δ) was calculated using δ13C. The intercorrelations among BAI, Δ, and environmental variables were explored. The BAI was positively (p

Carbon isotope ratio ( 13 C/ 12 C, expressed as δ 13 C) of tree ring can be proxy of atmospheric CO2 concentration ((CO2)) due to the inter-correlation between atmospheric (CO2), δ 13 C of atmospheric CO2, and δ 13 C of plant tissue that assimilates atmospheric CO2. This study was conducted to investigate if δ 13 C of tree ring of Pinus densiflora in polluted area may show a lower value than that in unpolluted area and to explore the possibility of reconstructing atmospheric (CO2) using its relationship with δ 13 C of tree ring. During the period between 1999 and 2005, δ 13 C of tree annual ring tended to decrease over time, and the δ 13 C in polluted area (-27.2‰ in 2009 to -28.3‰ in 2005) was significantly (P

To test the possible use of tree ring chemical properties as proxies for precipitation acidity ([H+]), we investigated the relationships between tree ring chemistry (δ13C, δ15N, Ca-to-Al ratio, and N concentration) of Pinus densiflora and precipitation [H+] between 1992 and 2005 in an industrial area in the southwest region of South Korea. Statistical analyses showed that all tree ring chemistry parameters were significantly correlated with precipitation [H+]. Tree ring δ13C was negatively correlated with precipitation acidity (r = −0.67, P < 0.01), reflecting the photosynthetic fixation of 13C-depleted CO2 from fossil fuel combustion that would be the primary source of precipitation acidity. A positive correlation of N concentration (r = 0.89, P < 0.001) and a negative correlation of δ15N (r = −0.63, P < 0.05) in tree rings with precipitation acidity most likely reflected the influence of 15N-depleted N compounds deposited via precipitation. The Ca-to-Al ratio was negatively (r = −0.58, P < 0.05) correlated with precipitation acidity, indicating that soil acidification caused the loss of Ca from the soil and solubilization of Al resulting from acid precipitation. Such relationships suggest that δ13C, δ15N, N concentration, and Ca-to-Al ratio in tree rings can be reliably used to evaluate the impact of acid precipitation on the studied P. densiflora stands.

Natural abundances of carbon-13 and nitrogen-15 were analyzed in 3-year bands of annual rings of three red pine (Pinus densiflora Sieb. et Zucc.) trees in eastern Korea to elucidate their variations in relation to changing environmental conditions, particularly air pollution. Tree ring width had a trend to decrease with time (r = −0.79, P < 0.001); however, tree-ring indices did not show any consistent pattern of change over time. Tree ring indices were correlated neither with the respective precipitation nor temperature. The δ13C (range: −25.7 to −24.4a) of tree rings became less negative as tree ring indices increase (r = 0.43, P < 0.05), suggesting that radial growth of trees might have been affected by environmental factors such as nutrient deficiency and acid rain that affect carboxylation efficiency. Increasing N concentration (range: 0.40 to 0.68 g N kg−1) with decreasing δ15N (range: +4.2 to −0.6a) of tree rings (r = −0.84, P < 0.01) during the period (since 1980s) of increasing NO x emission in Korea was consistent with the hypothesis that increasing deposition of N depleted in 15N may lead to 15N depletion in tree tissues. However, quantitative information on inter-ring translocation of N which may cause N isotopic fractionation is necessary to use the δ15N signal as a reliable indicator of air pollution.

This study was performed to establish standard methods and media for detecting S. Enteritidis in Korean style foods. For the preliminary experiment, the enrichment procedures for the recovery of acid or heat injured S. Enteritidis was compared. In the mixed culture system, Salmonella Enteritidis ATCC 13076, Shigella sonnei ATCC 9290, Staphylococcus aureus ATCC 25923, Listeria monocytogenes ATCC 19111, Escherichia coli ATCC 25922 were used. S. Enteritidis in food system were evaluated by using 5 different preenrichment media (TSB: Tryptic Soy Broth, LB: Lactose Broth, BPW: Buffered Peptone Water, SB: Selenite Broth, SCB: Selenite Cystine Broth) and 2 different enrichment media (TT: Tetrathionate Broth, RV: Rappaport and Vassiliadis). TSB was the most effective medium to detect acid and heat injured S. Enteritidis after 6 h incubation, but SB and SCB were also effective after 24 h incubation. For the recovery of heat injured S. Enteritidis at 65C, 5 pre-enrichment media did not show significant differences (P

Effects of nitrogen addition on the growth of Indigofera pseudo-tinctoria (Leguminosae) in the waste landfill site was investigated. Nitrogen fertilization in the nitrogen poor soils of waste landfill may influence the growth of nitrogen fixing plants beneficially or detrimentally. When I. pseudo-tinctoria was fertilized with three different levels of nitrogen, the coverage of plants treated with 46 g N/ and 460 g N/ was significantly less than that of plants treated with 23 g N/. The growth rates of plant height treated with 46 g N/ and 460 g N/ were significantly less than those of plants treated with 23 g N/. The growth rates of plant diameter treated with 46 g N/ and 460 g N/ were significantly less than those of plants treated with 23 g N/. Dry weights of whole plants in control sites were higher than those of all the others nitrogen treatment sites. Nodule numbers were higher in control plants than those of plants in all the other nitrogen treatment sites. It is suggested that nitrogen fertilizer addition over 23 g N/ affect the growth of some nitrogen fixing plants, such as I. pseudo-tinctoria, negatively.