ALBERT

Description: ABSTRACT The major toxic mechanism of Microcystin-LR is inhibition of the activity of protein phosphatase 2A (PP2A), resulting in a series of cytotoxic effects. Our previous studies have demonstrated that microcystin-LR (MCLR) induced very different molecular effects in normal cells and the tumor cell line SMMC7721. To further explore the MCLR toxicity mechanism in tumor cells, human laryngeal epithelial cells (Hep-2) was examined in this study. Western blot, immunofluorescence, immunoprecipitation, and transwell migration assay were used to detect the effects of MCLR on PP2A activity, PP2A substrates, cytoskeleton, and cell migration. The results showed that the protein level of PP2A subunits and the posttranslational modification of the catalytic subunit were altered and that the binding of the AC core enzyme as well as the binding of PP2A/C and α4, was also affected. As PP2A substrates, the phosphorylation of MAPK pathway members, p38, ERK1/2, and the cytoskeleton-associated proteins, Hsp27, VASP, Tau, and Ezrin were increased. Furthermore, MCLR induced reorganization of the cytoskeleton and promoted cell migration. Taken together, direct covalent binding to PP2A/C, alteration of the protein levels and posttranslational modification, as well as the binding of subunits, are the main pattern for the effects of MCLR on PP2A in Hep-2. A dose-dependent change in p-Tau and p-Ezrin due to PP2A inhibition may contribute to the changes in the cytoskeleton and be related to the cell migration in Hep-2. Our data provide a comprehensive exposition of the MCLR mechanism on tumor cells. © 2016 Wiley Periodicals, Inc. Environ Toxicol, 2016.

Description: Naphthenic acids (NAs) have been gaining recognition in recent years as potentially harmful environmental contaminants. Few studies have focused on the potential ecotoxicity of NAs to terrestrial environment. In this study, the responses of antioxidant system and lipid peroxidation and DNA damage were investigated after exposing Eisenia fetida to soil contaminated with NAs. The results indicated that NAs induced a significant increase ( p  〈 0.05) in superoxide dismutase and catalase enzyme activities. The glutathione peroxidase enzyme activities were significantly inhibited ( p  〈 0.05) in the medium and high dose treatments. An increase in malondialidehyde indicated that NAs could cause cellular lipid peroxidation in the tested earthworms. The percentage of DNA in the tail of comet assay of coelomocytes as an indication of DNA damage increased after treatment with different doses of NAs, and a dose-dependent DNA damage of coelomocytes was found. In conclusion, oxidative stress caused by NAs exposure induces physiological responses and genotoxicity on earthworms. © 2015 Wiley Periodicals, Inc. Environ Toxicol, 2015.

Description: Background: Sequences up to several megabases in length have been found to be present in individual genomes but absent in the human reference genome. These sequences may be common in populations, and their absence in the reference genome may indicate rare variants in the genomes of individuals who served as donors for the human genome project. As the reference genome is used in probe design for microarray technology and mapping short reads in next generation sequencing (NGS), this missing sequence could be a source of bias in functional genomic studies and variant analysis. One End Anchor (OEA) and/or orphan reads from paired-end sequencing have been used to identify novel sequences that are absent in reference genome. However, there is no study to investigate the distribution, evolution and functionality of those sequences in human populations. Results: To systematically identify and study the missing common sequences (micSeqs), we extended the previous method by pooling OEA reads from large number of individuals and applying strict filtering methods to remove false sequences. The pipeline was applied to data from phase 1 of the 1000 Genomes Project. We identified 309 micSeqs that are present in at least 1% of the human population, but absent in the reference genome. We confirmed 76% of these 309 micSeqs by comparison to other primate genomes, individual human genomes, and gene expression data. Furthermore, we randomly selected fifteen micSeqs and confirmed their presence using PCR validation in 38 additional individuals. Functional analysis using published RNA-seq and ChIP-seq data showed that eleven micSeqs are highly expressed in human brain and three micSeqs contain transcription factor (TF) binding regions, suggesting they are functional elements. In addition, the identified micSeqs are absent in non-primates and show dynamic acquisition during primate evolution culminating with most micSeqs being present in Africans, suggesting some micSeqs may be important sources of human diversity. Conclusions: 76% of micSeqs were confirmed by a comparative genomics approach. Fourteen micSeqs are expressed in human brain or contain TF binding regions. Some micSeqs are primate-specific, conserved and may play a role in the evolution of primates.

Description: The critically-important at-a-station hydraulic geometry (AHG) relationships relate hydraulic variables (depth, width, or velocity) to discharge in power-law form. The recently discovered at-many-stations hydraulic geometry (AMHG) states that AHG exponents and coefficients are strongly correlated, removing one parameter and lending AMHGs to remote-sensing discharge estimation. Despite the excitement, there is an urgent need to clarify AMHG's geomorphological significance for different hydraulic variables. Using data from 57 rivers in the US and perturbation experiments, we show that the width-AMHG is weak, arising mainly from the mathematical construct involving the exponent in both the regressor and the regressand. In contrast, the depth AMHGs result from geomorphological co-evolution. The similar-time-mean condition, as argued for in the literature, is sufficient but not necessary for rating curve convergence and in turn AMHG, for depth and velocity. The predictive accuracy of AMHGs, whose coefficient of determination is unit-dependent, is similar to the flow-percentile-based downstream hydraulic geometry.

Description: Surface patterning of the bond coat using a three-dimensional mesh offers a promising approach to improve the durability of the thermal barrier coatings (TBCs), in which the geometry parameters of the mesh play a vital role. The objective of this work is to investigate the failure behavior of the air-plasma sprayed TBCs with mesh, and to identify the optimal mesh design. The study revealed that the failure sequence of the TBCs with mesh patterns consisted of (I) initiation of the interfacial and ridge cracks (around the top of the mesh); (II) cracks propagation and buckling of the YSZ layer; (III) interfacial cracks deflection and coalescence with ridge cracks, leading to final spallation. The critical parameters governing each step of the failure sequence were discussed and proposed. For a typical TBCs with YSZ thickness about 200 μm, the critical mesh height h and spacing length L is about 110 μm and 7 mm, respectively, when the mesh width w is fixed at about 480 μm.

Description: Manganese oxides are good candidates of strongly correlated electron materials due to the uniqueness of electronic structure of manganese and the mobility of oxygen among lattice sites under external impacts. Here, we used electron beam as the excitation source to explore the structural evolution of YMnO 3 and identified a new phase under the radiation of electron beam in the transmission electron microscope. Analyses of the electron energy-loss spectra reveal that this phase originates from ordered oxygen vacancy. We applied the first principles calculation to pick out the optimized stable structure with a lower polarization, and verified its correctness by electron diffraction and image simulations. Analyses of density of states indicate that weak Y – O covalence is favorable for the existence of ferroelectricity, supporting the electrostatic nature of ferroelectricity in the YMnO 3 .

Description: Dynamic triggering in western Fangshan Pluton, Beijing, China has been repeatedly identified, but previous studies are limited by sparse seismic station coverage. Here we systematically analyze continuous waveforms recorded by both permanent stations and a temporary seismic network 40 days before and after the March 11 th 2011 M w 9.1 Tohoku-Oki and the April 14 th 2012 M w 8.6 Indian Ocean earthquakes. We first build a template database using a short-term average to long-term average method. Next, we apply the matched filter technique that cross-correlates the template waveforms with continuous data to detect additional seismic events. Overall we detect 1956 and 950 seismic events around the Tohoku-Oki and Indian Ocean mainshocks, respectively. Most detected events are shallow (〈5km) and clustered at Beiling Syncline in western Fangshan Pluton, which is adjacent to a running coalmine. 7 and 10 events are detected during the large-amplitude surface waves of the two mainshocks, respectively, but no similar burst is detected following their major foreshock and aftershocks. Multiple statistical tests indicate that the short-term bursts after the two mainshocks are dynamically triggered. We suggest that mining-related activities may perturb the subsurface stress conditions and hence make the region more susceptible for dynamic triggering than other places.

Description: ABSTRACT Microcystin-LR (MC-LR) is one of the most toxic members of microcystins released by freshwater cyanobacterial. The major mechanism of MC-LR toxicity has been attributed to its inhibition of protein phosphatases 1 (PP1) and 2A (PP2A). In our prior research, α4 protein, a regulator of PP2A, was found not only crucial for PP2A regulation but also for the overall response of HEK 293 cells encountering MC-LR. To explore the role of α4 in MC-LR toxicity via PP2A regulation, here, HEK 293 cells overexpressing α4 protein were exposed to MC-LR and PP2A, cytoskeletal organization, and cytoskeleton-related proteins were investigated. The results showed that PP2A activity decreased and PP2A/C subunit expression and phosphorylation at Tyr307 increased significantly in the group exposed to high MC-LR. Vimentin IF became concentrated and formed perinuclear bundles. However, the assembly of actin filament and microtubules remained unchanged and the expression and phosphorylation of the cytoskeleton-related proteins HSP27 and VASP did not increase significantly. Some of these results differ from those of our previous study in which normal HEK293 cells were exposed to MC-LR. Our results indicate that elevated α4 expression confers some resistance to MC-LR-induced cytoskeletal change These new findings provide helpful insights into the mechanism of MC-LR toxicity and the role of α4 in regulating PP2A function. © 2015 Wiley Periodicals, Inc. Environ Toxicol, 2015.

Description: The datasets of National Centers for Environmental Prediction (NCEP I and II) and Climatic Research Unit – NCEP (CRUNCEP) were evaluated by comparing against observational data from the National Oceanic and Atmospheric Administration (NOAA) at monthly and annual scales, site and regional scales. The evaluations were conducted for air temperature (maximum, mean, and minimum) and precipitation at the 90 largest cities across the United States. At annual scale, NCEP I, NCEP II and CRUNCEP were slightly yet significantly underestimated for mean temperature (1%) and maximum temperatures (1%). The NCEP I was significantly underestimated for minimum temperature (1%) while overestimated for total precipitation (16%); the NCEP II was significantly underestimated for minimum temperature (2%) and total precipitation (2%); the CRUNCEP was significantly overestimated for minimum temperature (2%) and total precipitation (6%). At monthly scale, three datasets were underestimated for a majority of months in terms of monthly mean temperature, monthly maximum temperature, monthly minimum temperature, and monthly total precipitation except an overestimation of CRUNCEP on minimum temperature (48%) and monthly total precipitation (43%). At the seasonal scale, three datasets had smaller biases in summer season and larger biases in winter season for temperature, while larger biases in summer season and smaller biases in winter seasons for precipitation. Overall, the CRUNCEP dataset had a slightly better performance than NCEP I and NCEP II datasets. This multi-scale evaluation of the three most-widely used regional climate datasets provides insightful information for atmospheric science studies, particularly urban heat impact investigation.