Different response of phytochelatins in two aquatic macrophytes exposed to cadmium at environmentally relevant concentrations

Phytochelatins (PCs) have been proposed as potential biomarkers for an evaluation of metal toxicity. However, most studies have been generally limited to high concentrations of metals. In this study, two submerged macrophytes Ceratophyllum demersum L. and Elodea canadensis Michx. were adopted to investigate the response of phytochelatins (PCs) and its relationship with cadmium (Cd) toxicity upon exposure to low concentrations of Cd (0.01 to 0.64 μM) usually present in low or moderately polluted environments. It was observed that, 0.01 to 0.04 μM Cd had no obvious toxic effects on the growth of two plants compared with the control plants, whereas Cd toxicity is significantly seen in C. demersum at 0.08 to 0.64 μM and in E. canadensis at 0.16 to 0.64 μM, as indicated by the significant decreases of fresh weights. Two plants showed strong capacity to accumulate Cd present in low concentrations. PCs were produced in a dependent-species and-concentration manner. Response of PCs was strong in C. demersum exposed to Cd concentrations studied (0.02 to 0.64 μM) and dramatically increased with the increase of Cd concentrations in solutions. The maximum amount of PCs in C. demersum was found at 7 days and obviously decreased with the prolonged exposure to Cd. PC concentrations in C. demersum were positively correlated with Cd toxicity, as measured by the growth inhibition rate of fresh weight. By contrast, Cd concentrations studied slightly or mildly induced the production of PCs in E. canadensis. The results suggested that, positive responses of PCs in C. demersum can serve as early biomarkers for reflecting Cd toxicity in low or moderately polluted water environments.Key words: Biomarker, cadmium, Ceratophyllum demersum L., Elodea canadensis Michx., metal toxicity, phytochelatins

Effects of different annealing gases on pentacene OTFT with HfLaO gate dielectric

Pentacene organic thin-film transistors (OTFTs) with HfLaO high-kappa gate dielectric were fabricated. The dielectric was prepared by a sputtering method and then annealed in N2,NH3,O2, or NO at 400°C. The carrier mobility of the NH3-annealed OTFT could reach 0.59 cm2/V̇s, which is higher than those of the other three devices. Moreover, the NH3-annealed OTFT obtained the smallest subthreshold swing of 0.26 V/dec among them. Furthermore,1/f noise measurement indicated that the NH3-annealed OTFT achieved the smallest 1/f noise. All these should be attributed to the improved interface between the gate dielectric and the organic semiconductor associated with the passivation effects of the NH3 annealing on the dielectric surface. © 2010 IEEE.published_or_final_versio

Seroprevalence of Toxoplasma gondii in pregnant women and livestock in the mainland of China : a systematic review and hierarchical meta-analysis

Primary Toxoplasma gondii infection in pregnant women may result in abortion, stillbirth, or lifelong disabilities of the unborn child. One of the main transmission routes to humans is consumption of raw or undercooked meat containing T. gondii tissue cysts. We aim to determine and compare the regional distribution of T. gondii seroprevalence in pregnant women and meat-producing livestock in China through a systematic literature review. A total of 272 eligible publications were identified from Medline, Scopus, Embase and China National Knowledge Infrastructure. Apparent and true seroprevalence were analysed by region using a novel Bayesian hierarchical model that allowed incorporating sensitivity and specificity of the applied serological assays. The true seroprevalence of T. gondii in pregnant women was 5.0% or less in seven regions of China. The median of the regional true seroprevalences in pigs (24%) was significantly higher than in cattle (9.5%), but it was not significantly higher than in chickens (20%) and small ruminants (20%). This study represents the first use of a Bayesian hierarchical model to obtain regional true seroprevalence. These results, in combination with meat consumption data, can be used to better understand the contribution of meat-producing animals to human T. gondii infection in China

A comparison of efficacy between conventional and modified methods of the chronic myocardial ischemia/reperfusion model

The objective of this study is to develop and compare the efficacy of a modified versus conventional rat model of chronic myocardial ischemia/reperfusion. Sixty Sprague Dawley (SD) rats were randomlydivided into two groups, a modified group (mask respiratory support and short-time chest-opening) and a conventional group (tracheal intubation and long-time chest-opening). Operation time, surgical success rate, survival rate and infarct size were investigated. In addition, the post-operative living state of the rats was observed. In the perioperative period, the surgical success rate was greater in the modified model (P 0.05). The modified method offers advantages of simplicity, efficiency and independent conduct. Its employment enhances the success rate of the chronic rat myocardial ischemia/reperfusion model

EM23, a natural sesquiterpene lactone, targets thioredoxin reductase to activate JNK and cell death pathways in human cervical cancer cells

Sesquiterpene lactones (SLs) are the active constituents of a variety of medicinal plants and found to have potential anticancer activities. However, the intracellular molecular targets of SLs and the underlying molecular mechanisms have not been well elucidated. In this study, we observed that EM23, a natural SL, exhibited anti-cancer activity in human cervical cancer cell lines by inducing apoptosis as indicated by caspase 3 activation, XIAP downregulation and mitochondrial dysfunction. Mechanistic studies indicated that EM23-induced apoptosis was mediated by reactive oxygen species (ROS) and the knockdown of thioredoxin (Trx) or thioredoxin reductase (TrxR) resulted in a reduction in apoptosis. EM23 attenuated TrxR activity by alkylation of C-terminal redox-active site Sec498 of TrxR and inhibited the expression levels of Trx/TrxR to facilitate ROS accumulation. Furthermore, inhibition of Trx/TrxR system resulted in the dissociation of ASK1 from Trx and the downstream activation of JNK. Pretreatment with ASK1/JNK inhibitors partially rescued cells from EM23-induced apoptosis. Additionally, EM23 inhibited Akt/mTOR pathway and induced autophagy, which was observed to be proapoptotic and mediated by ROS. Together, these results reveal a potential molecular mechanism for the apoptotic induction observed with SL compound EM23, and emphasize its putative role as a therapeutic agent for human cervical cancer.published_or_final_versio

An assessment of western North Pacific ozone photochemistry based on springtime observations from NASA's PEM-West B (1994) and TRACE-P (2001) field studies

The current study provides a comparison of the photochemical environments for two NASA field studies focused on the western North Pacific (PEM-West-B (PWB) and TRACE-P (TP)). These two studies were separated in calendar time by approximately 7 years. Both studies were carried out under springtime conditions, with PWB being launched in 1994 and TP being deployed in 2001 (i.e., 23 February - 15 March 1994 and 10 March-15 April 2001, respectively). Because of the 7-year time separation, these two studies presented a unique scientific opportunity to assess whether evidence could be found to support the Department of Energy\u27s projections in 1997 that increases in anthropogenic emissions from East Asia could reach 5%/yr. Such projections would lead one to the conclusion that a significant shift in the atmospheric photochemical properties of the western North Pacific would occur. To the contrary, the findings from this study support the most recent emission inventory data [Streets et al., 2003] in that they show no significant systematic trend involving increases in any O3 precursor species and no evidence for a significant shift in the level of photochemical activity over the western North Pacific. This conclusion was reached in spite of there being real differences in the concentration levels of some species as well as differences in photochemical activity between PWB and TP. However, nearly all of these differences were shown to be a result of a near 3-week shift in TP\u27s sampling window relative to PWB, thus placing it later in the spring season. The photochemical enhancements seen during TP were most noticeable for latitudes in the range of 25-45°N. Most important among these were increases in J(O1D), OH, and HO2 and values for photochemical ozone formation and destruction, all of which were typically two times larger than those calculated for PWB. A comparison of these airborne results with ozonesonde data from four Japanese stations provided further evidence showing that the 3-week shift in the respective sampling windows of PWB and TP was a likely cause for the differences seen in O3 levels and in photochemical activity between the two airborne studies. Copyright 2003 by the American Geophysical Union

Effects of quantum gravity on the inflationary parameters and thermodynamics of the early universe

The effects of generalized uncertainty principle (GUP) on the inflationary dynamics and the thermodynamics of the early universe are studied. Using the GUP approach, the tensorial and scalar density fluctuations in the inflation era are evaluated and compared with the standard case. We find a good agreement with the Wilkinson Microwave Anisotropy Probe data. Assuming that a quantum gas of scalar particles is confined within a thin layer near the apparent horizon of the Friedmann-Lemaitre-Robertson-Walker universe which satisfies the boundary condition, the number and entropy densities and the free energy arising form the quantum states are calculated using the GUP approach. A qualitative estimation for effects of the quantum gravity on all these thermodynamic quantities is introduced.Comment: 15 graghes, 7 figures with 17 eps graph