Mechanisms of algal biomass input enhanced microbial Hg methylation in lake sediments

Eutrophication is a major environmental concern in lake systems, impacting the ecological risks of contaminants and drinking water safety. It has long been believed that eutrophication and thus algal blooms would reduce methylmercury (MeHg) levels in water, as well as MeHg bioaccumulation and trophic transfer (e.g., by growth dilution). In this study, however, we demonstrated that algae settlement and decomposition after algal blooms increased MeHg levels in sediments (54-514% higher), as evidenced by the results from sediments in 10 major lakes in China. These could in turn raise concerns about enhanced trophic transfer of MeHg and deterioration of water quality after algal blooms, especially considering that 9 out of the 10 examined lakes also serve as drinking water sources. The enhanced microbial MeHg production in sediments could be explained by the algal organic matter (AOM)-enhanced abundances of microbial methylators as well as the input of algae-inhabited microbes into sediments, but not Hg speciation in sediments: (1) Several AOM components (e.g., aromatic proteins and soluble microbial by product-like material with generally low molecular weights), rather than the bulk AOM, played key roles in enhancing the abundances of microbial methylators. The copies of Archaea-hgcA methylation genes were 51-397% higher in algae-added sediments; thus, MeHg production was also higher. (2) Input of algal biomass-inhabited microbial methylators contributed to 2-21% of total Archaea-hgcA in the 10 lake sediments with added algal biomass. (3) However, AOM-induced changes in Hg speciation, with implications on Hg availability to microbial methylators, played a minor role in enhancing microbial Hg methylation in sediments as seen in X-ray absorption near edge structure (XANES) data. Our results suggest the need to better understand the biogeochemistry and risks of contaminants in eutrophic lakes, especially during the period of algae settlement and decomposition following algal blooms.China Postdoctoral Science Foundation 2017M622782 National Natural Science Foundation of China 41676095 41673075 Natural Science Foundation of Jiangsu Province BK20160067info:eu-repo/semantics/acceptedVersio

Testing Price Pressure, Information, Feedback Trading, and Smoothing Effects for Energy Exchange Traded Funds

This paper examines the relationships between flows and returns for five Exchange Traded Funds (ETF) in the U.S. energy sector. Four alternative hypotheses are tested, including the price pressure hypothesis, information (or price release) hypothesis, feedback trading hypothesis, and smoothing hypothesis. The five ETF are the Energy Select Sector SPDR Fund (XLE), iShares U.S. Energy ETF (IYE), iShares Global Energy ETF (IXC), Vanguard Energy ETF (VDE), and PowerShares Dynamic Energy Exploration & Production Portfolio (PXE). A Vector Autoregressive (VAR) model is used to analyze the relationships between energy flows and returns. The empirical results show that energy returns and subsequent energy ETF flows have a negative relationship, thereby supporting the smoothing hypothesis. Moreover, the smoothing effect exists for XLE and IYE during the global financial crisis. Regardless of whether the whole sample period or the sub-samples before, during and after the global financial crisis are used, no evidence is found in support of the price pressure hypothesis, information hypothesis, or feedback trading hypothesis

Testing Price Pressure, Information, Feedback Trading, and Smoothing Effects for Energy Exchange Traded Funds

This paper examines the relationships between flows and returns for five Exchange Traded Funds (ETF) in the U.S. energy sector. Four alternative hypotheses are tested, including the price pressure hypothesis, information (or price release) hypothesis, feedback trading hypothesis, and smoothing hypothesis. The five ETF are the Energy Select Sector SPDR Fund (XLE), iShares U.S. Energy ETF (IYE), iShares Global Energy ETF (IXC), Vanguard Energy ETF (VDE), and PowerShares Dynamic Energy Exploration & Production Portfolio (PXE). A Vector Autoregressive (VAR) model is used to analyze the relationships between energy flows and returns. The empirical results show that energy returns and subsequent energy ETF flows have a negative relationship, thereby supporting the smoothing hypothesis. Moreover, the smoothing effect exists for XLE and IYE during the global financial crisis. Regardless of whether the whole sample period or the sub-samples before, during and after the global financial crisis are used, no evidence is found in support of the price pressure hypothesis, information hypothesis, or feedback trading hypothesis

A controllable superconducting electromechanical oscillator with a suspended membrane

We fabricate a microscale electromechanical system, in which a suspended superconducting membrane, treated as a mechanical oscillator, capacitively couples to a superconducting microwave resonator. As the microwave driving power increases, nonmonotonic dependence of the resonance frequency of the mechanical oscillator on the driving power has been observed. We also demonstrate the optical switching of the resonance frequency of the mechanical oscillator. Theoretical models for qualitative understanding of our experimental observations are presented. Our experiment may pave the way for the application of a mechanical oscillator with its resonance frequency controlled by the electromagnetic and/or optical fields, such as a microwave-optical interface and a controllable element in a superqubit-mechanical oscillator hybrid system.Comment: 8 pages,4 figure

Effects of resveratrol supplementation on methotrexate chemotherapy‐induced bone loss

Intensive cancer chemotherapy is known to cause bone defects, which currently lack treatments. This study investigated the effects of polyphenol resveratrol (RES) in preventing bone defects in rats caused by methotrexate (MTX), a commonly used antimetabolite in childhood oncology. Young rats received five daily MTX injections at 0.75 mg/kg/day. RES was orally gavaged daily for seven days prior to, and during, five‐day MTX administration. MTX reduced growth plate thickness, primary spongiosa height, trabecular bone volume, increased marrow adipocyte density, and increased mRNA expression of the osteogenic, adipogenic, and osteoclastogenic factors in the tibial bone. RES at 10 mg/kg was found not to affect bone health in normal rats, but to aggravate the bone damage in MTX‐treated rats. However, RES supplementation at 1 mg/kg preserved the growth plate, primary spongiosa, bone volume, and lowered the adipocyte density. It maintained expression of genes involved in osteogenesis and decreased expression of adipogenic and osteoclastogenic factors. RES suppressed osteoclast formation ex vivo of bone marrow cells from the treated rats. These data suggest that MTX can enhance osteoclast and adipocyte formation and cause bone loss, and that RES supplementation at 1 mg/kg may potentially prevent these bone defects

Comparative analysis of long noncoding RNAs in angiosperms and characterization of long noncoding RNAs in response to heat stress in Chinese cabbage

Long noncoding RNAs (lncRNAs) are widely present in different species and play critical roles in response to abiotic stresses. However, the functions of lncRNAs in Chinese cabbage under heat stress remain unknown. Here, we first conducted a global comparative analysis of 247,242 lncRNAs among 37 species. The results indicated that lncRNAs were poorly conserved among different species, and only 960 lncRNAs were homologous to 524 miRNA precursors. We then carried out lncRNA sequencing for a genome-wide analysis of lncRNAs and their target genes in Chinese cabbage at different stages of heat treatment. In total, 18,253 lncRNAs were identified, of which 1229 differentially expressed (DE) lncRNAs were characterized as being heat-responsive. The ceRNA network revealed that 38 lncRNAs, 16 miRNAs, and 167 mRNAs were involved in the heat response in Chinese cabbage. Combined analysis of the cis- and trans-regulated genes indicated that the targets of DE lncRNAs were significantly enriched in the “protein processing in endoplasmic reticulum” and “plant hormone signal transduction” pathways. Furthermore, the majority of HSP and PYL genes involved in these two pathways exhibited similar expression patterns and responded to heat stress rapidly. Based on the networks of DE lncRNA-mRNAs, 29 and 22 lncRNAs were found to interact with HSP and PYL genes, respectively. Finally, the expression of several critical lncRNAs and their targets was verified by qRT-PCR. Overall, we conducted a comparative analysis of lncRNAs among 37 species and performed a comprehensive analysis of lncRNAs in Chinese cabbage. Our findings expand the knowledge of lncRNAs involved in the heat stress response in Chinese cabbage, and the identified lncRNAs provide an abundance of resources for future comparative and functional studies