Impact of forest fire on radial growth of tree rings and their element concentrations of Pinus sylvestris and Larix gmelinii in northern China

AimsThrough analyzing the responses of the radial growth and element concentrations (B, Mg, Al, K, Ca, Mn, Fe, Zn, Na, P, Ni, and Cu) of tree rings of two dominant tree species to forest fires, we aimed to investigate the relationship between tree rings and the fires. MethodsWe sampled wood cores of Pinus sylvestris and Larix gmelinii in the northern forest region of China, where forest fires happened in 1990 and 2008. The ring-width growth of P. sylvestris and L. gmelinii from 1986 to 1995 and 2004 to 2013 in two sites of Tahe County were measured. Element concentrations in tree rings were determined using inductively coupled plasma mass spectrometry (ICP-MS). ResultsOur results showed that tree-ring radial growth was largely reduced after the fire, together with the increase in concentrations of B, Al, Mn, and Fe but the decrease in some samples in K. Strong correlations were observed between tree-ring growth and concentrations of Mg and Mn of P. sylvestris and Znof L. gmelinii. DiscussionThe results provide evidence that variations in tree-ring growth and element concentrations, particularly concentrations of B, Al, Mn, and Fe, are potentially useful to monitor forest fires, which add new insights into the study of forest fire history

Boosting oxygen evolution over inverse spinel Fe-Co-Mn oxide nanocubes through electronic structure engineering

Fossil fuels are urgent to be replaced with renewable energies to achieve carbon neutrality. Intermittent renewable energies such as solar and wind could be stored in chemical bonds, such as hydrogen and carbon-containing chemicals through water and CO2 electrolyzers respectively. Those two energy systems share a common anodic reaction, the sluggish oxygen evolution reaction (OER), which currently relies on precious noble metals to achieve a reasonable energy conversion efficiency. Herein, tuning the d-band center of Fe-based inverse spinel oxides has been achieved through compositions and morphologies engineering. Ternary Mn0.5Co0.5Fe2O4 nanocubes exhibit oxygen evolution activity superior to the benchmark RuO2. Mössbauer and in-situ infrared spectra combined with density functional theory calculations prove that the optimized d-band center offers a balanced adsorption strength of intermediate *OOH on Mn0.5Co0.5Fe2O4 nanocubes. This work provides a promising approach to the design and synthesis of highly efficient electrocatalysts beyond oxygen evolution.</p

Critical Roles of microRNA-141-3p and CHD8 in Hypoxia/Reoxygenation-Induced Cardiomyocyte Apoptosis

Background: Cardiovascular diseases are currently the leading cause of death in humans. The high mortality of cardiac diseases is associated with myocardial ischemia and reperfusion (I/R). Recent studies have reported that microRNAs (miRNAs) play important roles in cell apoptosis. However, it is not known yet whether miR-141-3p contributes to the regulation of cardiomyocyte apoptosis. It has been well established that in vitro hypoxia/reoxygenation (H/R) model can follow in vivo myocardial I/R injury. This study aimed to investigate the effects of miR-141-3p and CHD8 on cardiomyocyte apoptosis following H/R. Results: We found that H/R remarkably reduces the expression of miR-141-3p but enhances CHD8 expression both in mRNA and protein in H9c2 cardiomyocytes. We also found either overexpression of miR-141-3p by transfection of miR-141-3p mimics or inhibition of CHD8 by transfection of small interfering RNA (siRNA) significantly decrease cardiomyocyte apoptosis induced by H/R. Moreover, miR-141-3p interacts with CHD8. Furthermore, miR-141-3p and CHD8 reduce the expression of p21. Conclusion: MiR-141-3p and CHD8 play critical roles in cardiomyocyte apoptosis induced by H/R. These studies suggest that miR-141-3p and CHD8 mediated cardiomyocyte apoptosis may offer a novel therapeutic strategy against myocardial I/R injury-induced cardiovascular diseases

Analysis of tall fescue ESTs representing different abiotic stresses, tissue types and developmental stages

<p>Abstract</p> <p>Background</p> <p>Tall fescue (<it>Festuca arundinacea </it>Schreb) is a major cool season forage and turf grass species grown in the temperate regions of the world. In this paper we report the generation of a tall fescue expressed sequence tag (EST) database developed from nine cDNA libraries representing tissues from different plant organs, developmental stages, and abiotic stress factors. The results of inter-library and library-specific <it>in silico </it>expression analyses of these ESTs are also reported.</p> <p>Results</p> <p>A total of 41,516 ESTs were generated from nine cDNA libraries of tall fescue representing tissues from different plant organs, developmental stages, and abiotic stress conditions. The <it>Festuca </it>Gene Index (FaGI) has been established. To date, this represents the first publicly available tall fescue EST database. <it>In silico </it>gene expression studies using these ESTs were performed to understand stress responses in tall fescue. A large number of ESTs of known stress response gene were identified from stressed tissue libraries. These ESTs represent gene homologues of heat-shock and oxidative stress proteins, and various transcription factor protein families. Highly expressed ESTs representing genes of unknown functions were also identified in the stressed tissue libraries.</p> <p>Conclusion</p> <p>FaGI provides a useful resource for genomics studies of tall fescue and other closely related forage and turf grass species. Comparative genomic analyses between tall fescue and other grass species, including ryegrasses (<it>Lolium </it>sp.), meadow fescue (<it>F. pratensis</it>) and tetraploid fescue (<it>F. arundinacea var glaucescens</it>) will benefit from this database. These ESTs are an excellent resource for the development of simple sequence repeat (SSR) and single nucleotide polymorphism (SNP) PCR-based molecular markers.</p

Targeted metabolome and transcriptome analyses reveal changes in gibberellin and related cell wall-acting enzyme-encoding genes during stipe elongation in Flammulina filiformis

Flammulina filiformis, a typical agaric fungus, is a widely cultivated and consumed edible mushroom. Elongation of its stipe (as the main edible part) is closely related to its yield and commercial traits; however, the endogenous hormones during stipe elongation and their regulatory mechanisms are not well understood. Gibberellin (GA) plays an important role in the regulation of plant growth, but little has been reported in macro fungi. In this study, we first treated F. filiformis stipes in the young stage with PBZ (an inhibitor of GA) and found that PBZ significantly inhibited elongation of the stipe. Then, we performed GA-targeted metabolome and transcriptome analyses of the stipe at both the young and elongation stages. A total of 13 types of GAs were detected in F. filiformis; the contents of ten of them, namely, GA3, GA4, GA8, GA14, GA19, GA20, GA24, GA34, GA44, and GA53, were significantly decreased, and the contents of three (GA5, GA9, and GA29) were significantly increased during stipe elongation. Transcriptome analysis showed that the genes in the terpenoid backbone biosynthesis pathway showed varying expression patterns: HMGS, HMGR, GPS, and FPPS were significantly upregulated, while CPS/KS had no significant difference in transcript level during stipe elongation. In total, 37 P450 genes were annotated to be involved in GA biosynthesis; eight of them were upregulated, twelve were downregulated, and the rest were not differentially expressed. In addition, four types of differentially expressed genes involved in stipe elongation were identified, including six signal transduction genes, five cell cycle-controlling genes, twelve cell wall-related enzymes and six transcription factors. The results identified the types and content of GAs and the expression patterns of their synthesis pathways during elongation in F. filiformis and revealed the molecular mechanisms by which GAs may affect the synthesis of cell wall components and the cell cycle of the stipe through the downstream action of cell wall-related enzymes, transcription factors, signal transduction and cell cycle control, thus regulating stipe elongation. This study is helpful for understanding the roles of GAs in stipe development in mushrooms and lays the foundation for the rational regulation of stipe length in agaric mushrooms during production

Mitochondrial Uncoupling Inhibits p53 Mitochondrial Translocation in TPA-Challenged Skin Epidermal JB6 Cells

The tumor suppressor p53 is known to be able to trigger apoptosis in response to DNA damage, oncogene activation, and certain chemotherapeutic drugs. In addition to its transcriptional activation, a fraction of p53 translocates to mitochondria at the very early stage of apoptosis, which eventually contributes to the loss of mitochondrial membrane potential, generation of reactive oxygen species (ROS), cytochrome c release, and caspase activation. However, the mitochondrial events that affect p53 translocation are still unclear. Since mitochondrial uncoupling has been suggested to contribute to cancer development, herein, we studied whether p53 mitochondrial translocation and subsequent apoptosis were affected by mitochondrial uncoupling using chemical protonophores, and further verified the results using a siRNA approach in murine skin epidermal JB6 cells. Our results showed that mitochondrial uncoupling blocked p53 mitochondrial translocation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA), a known tumor promoter to induce p53-mediated apoptosis in skin carcinogenesis. This blocking effect, in turn, led to preservation of mitochondrial functions, and eventually suppression of caspase activity and apoptosis. Moreover, uncoupling protein 2 (UCP2), a potential suppressor of ROS in mitochondria, is important for TPA-induced cell transformation in JB6 cells. UCP2 knock down cells showed enhanced p53 mitochondrial translocation, and were less prone to form colonies in soft agar after TPA treatment. Altogether, our data suggest that mitochondrial uncoupling may serve as an important regulator of p53 mitochondrial translocation and p53-mediated apoptosis during early tumor promotion. Therefore, targeting mitochondrial uncoupling may be considered as a novel treatment strategy for cancer

Advanced Perceptive Forwarding in Content-Centric Networks

As the promising communication architecture for future networks, the content-centric network (CCN) is still facing many challenges. In CCNs, it is difficult to discover temporary content replicas spreading in routers' caches based on the routing information provided by proactive routing protocols. This paper proposes an advanced perceptive forwarding strategy (APFS), which adaptively perceives closer temporary content replicas to respond the users' requests quickly. A data structure, called a chunk map (CM), is designed and is included into a data packet to indicate the availability of the content replicas in the cache of a closer router. The routers that have received the CM seem to perceive the closer content replicas so that they would intelligently forward the users' requests to the closer routers that cache the requested content replicas. Moreover, a new policy, called early start with punishment, is put forward to guarantee the adaptability of the CM probing and an improved cache replacement policy is employed to extend the validity duration of the CM. The simulation result shows that our APFS scheme has the noticeable performance in terms of the download delay and the average bandwidth.Published versio

Chem. Eng. J.

5-Hydroxymethylfurfural (HMF) is a promising green platform chemical derived from biomass. Kinetic studies were performed on chromium chloride-catalyzed conversion of glucose into HMF in alkylimidazolium chloride ionic liquids. The main by-products are disaccharides, fructose, glyceraldehyde, formic acid, and humins. The formation of HMF is strongly affected by reaction temperature and initial glucose concentration. The reaction is second order in glucose, with an activation energy of 134.9 kJ mol(-1). The order in chromium is first, indicating that the rate-determining isomerization reaction is catalyzed by a mononuclear chromium species. The observed glucose conversion rate constant decreases as initial glucose concentration increases, suggesting that the catalytic activity of the chloride anion is significantly restrained by the hydrogen bonding with hydroxyl groups. A simplified kinetic model is developed to describe the behaviors of glucose conversion and HMF formation. This model is in good agreement with the experimental results. (C) 2013 Elsevier B.V. All rights reserved.5-Hydroxymethylfurfural (HMF) is a promising green platform chemical derived from biomass. Kinetic studies were performed on chromium chloride-catalyzed conversion of glucose into HMF in alkylimidazolium chloride ionic liquids. The main by-products are disaccharides, fructose, glyceraldehyde, formic acid, and humins. The formation of HMF is strongly affected by reaction temperature and initial glucose concentration. The reaction is second order in glucose, with an activation energy of 134.9 kJ mol(-1). The order in chromium is first, indicating that the rate-determining isomerization reaction is catalyzed by a mononuclear chromium species. The observed glucose conversion rate constant decreases as initial glucose concentration increases, suggesting that the catalytic activity of the chloride anion is significantly restrained by the hydrogen bonding with hydroxyl groups. A simplified kinetic model is developed to describe the behaviors of glucose conversion and HMF formation. This model is in good agreement with the experimental results. (C) 2013 Elsevier B.V. All rights reserved

p53 Is Necessary for the Apoptotic Response Mediated by a Transient Increase of Ras Activity

The tumor suppressor p53 eliminates cancer-prone cells via multiple mechanisms, including apoptosis. Ras elicits apoptosis in cells after protein kinase C (PKC) downregulation. However, the role of p53 in Ras-mediated apoptosis has not been fully investigated. Here, we demonstrate that mouse fibroblasts that express wild-type p53 are more susceptible to apoptosis elicited by PKC inhibition if Ras is transiently expressed or upregulated as opposed to stably expressed. In the latter case, p53 is frequently mutated. Transiently increased Ras activity induces Bax, and PKC inhibition augments this induction. Overexpression of E6 inactivates p53 and thereby suppresses both Bax induction and apoptosis. In contrast, Bax is not induced in stable ras transfectants, regardless of PKC inhibition. The data suggest that short- and long-term activation of Ras use a different mechanism(s) to initiate apoptosis. The status of p53 may contribute to such differences