Effects of copper oxide nanoparticles on reproductive system of zebrafish.

Copper oxide nanoparticles (CuO NPs) were regarded as the versatile materials in daily life and the in-depth evaluation of their biological effects is of great concern. Herein the female and male zebrafishes were chosen as the model animals to analyze the reproductive toxicity caused by CuO NPs at low concentration (10, 50 and 100 µg/L) After 20-days exposure, the structure of zebrafish ovary and testis were impaired. Moreover, the contents of 17ß-estradiol (E2) in both females and males were increased, while the contents of testosterone (T) were decreased, indicating the imbalanced sex hormones caused by CuO NPs. The expression of genes along the hypothalamic pituitary-gonad (HPG) axis, were examined with quantitative real-time PCR to further evaluate the toxic mechanisms. Meanwhile, the levels of erα/er2ß and cyp19a in female zebrafishes and erα/er2ß, lhr, hmgra/hmgrb, 3ßhsd and 17ßhsd in male zebrafishes were obviously up-regulated. While, the level of αr was obviously down-regulated in female and male zebrafishes. Thus, the obtained data uncovered that long-term exposure of CuO NPs with low dose could trigger the endocrine disorder, resulting in the disturbance of E2 and T level, inhibition of gonad development, and alteration of HPG axis genes. In brief, this study enriched the toxicological data of NPs on aquatic vertebrates and provided the theoretical support for assessing the environmental safety of NPs.

Chronic level of exposures to low-dosed MoS2 nanomaterials exhibits more toxic effects in HaCaT keratinocytes.

Molybdenum disulfide nanomaterials (MoS2 NMs) have shown significant role as photocatalysts, lubricating agents and sterilant due to their remarkable physicochemical properties. Because of the increasing demand for MoS2 NMs in numerous industrial domains, greater occupational exposure and subsequent NMs release into environment would be unavoidable. However, much efforts have been made to uncover the biological effects of NMs at unrealistic high concentration or acute duration, placing constraints on setting the realistic occupational exposure thresholds with confidence. In order to fill the current knowledge gap, this study aimed to evaluate the nanotoxicity of MoS2 NMs with or without surface defects under the more realistic exposure mode. Noteworthily, the artificial sweat transformed-occupational exposure-cytotoxicity investigation of MoS2 NMs was established as the main studied line. And the high cellular internalization and augmented oxidative stress triggered by surface defect could be recognized as the main factors for triggering serious cellular damage. Moreover, the HaCaTs exhibited loss of cell membrane integrity, dysfunction of mitochondria, disorder of endoplasmic reticulum and damages of nuclei after chronic exposure, compared with acute exposure. The study provided closely realistic exposure scenarios for NMs which exhibited significant difference from acute toxic investigation, enriching understanding towards real environmental safety of NMs.

Predicting the coordination geometry for Mg2+ in the p53 DNA-binding domain: insights from computational studies.

Zn(2+) in the tumor-suppressor protein p53 DNA-binding domain (DBD) is essential for its structural stability and DNA-binding specificity. Mg(2+) has also been recently reported to bind to the p53DBD and influence its DNA-binding activity. In this contribution, the binding geometry of Mg(2+) in the p53DBD and the mechanism of how Mg(2+) affects its DNA-binding activity were investigated using density functional theory (DFT) calculations and molecular dynamics (MD) simulations. Various possible coordination geometries of Mg(2+) binding to histidines (His), cysteines (Cys), and water molecules were studied at the B3LYP/6-311+g** level of theory. The protonation state of Cys and the environment were taken into account to explore the factors governing the coordination geometry. The free energy of the reaction to form the Mg(2+) complexes was estimated, suggesting that the favorable binding mode changes from a four- to six-coordinated geometry as the number of the protonated Cys increases. Furthermore, MD simulations were employed to explore the binding modes of Mg(2+) in the active site of the p53DBD. The simulation results of the Mg(2+) system and the native Zn(2+) system show that the binding affinity of Mg(2+)to the p53DBD is weaker than that of Zn(2+), in agreement with the DFT calculation results and experiments. In addition, the two metal ions are found to make a significant contribution to maintain a favorable orientation for Arg248 to interact with putative DNA, which is critically important to the sequence-specific DNA-binding activity of the p53DBD. However, the effect of Mg(2+) is less marked. Additionally, analysis of the natural bond orbital (NBO) charge transfer reveals that Mg(2+) has a higher net positive charge than Zn(2+), leading to a stronger electrostatic attractive interaction between Mg(2+) and putative DNA. This may partly explain the higher sequence-independent DNA-binding affinity of p53DBD-Mg(2+) compared to p53DBD-Zn(2+) observed in experiment.

Biosorption of Pb(II) by biomass of KC-2: kinetic, equilibrium and characteristic studies.

Performance and characteristics of biosorption of Pb(II) had been studied in a batch system using the fungal strain biomass, KC-2. The biosorption performance was investigated by analysing the effects of such factors as the initial pH, initial Pb(II) concentration, and contact time at 303 K. The maximum Pb(II) adsorption was obtained at pH 5.0. The experimental data were described by the pseudo first-order, pseudo second-order and intraparticle diffusion kinetic models, and were closely followed the pseudo second-order kinetic model. The equilibrium experimental data were well fitted to Langmuir model and the maximum biosorption capacity was 84.03 mg g(-1). The adsorption mechanism was examined by FTIR, SEM and EDAX analysis. Results indicated that carboxylic, hydroxyl and amine groups were involved in the biosorption and ion exchange mechanism existed.

Sensitive and selective determination of butyl benzyl phthalate from environmental samples using an enzyme immunoassay.

Increased awareness of phthalic acid esters (PAEs) toxicity has given rise to a dramatic increase in concern about the determination of these contaminations in the environment. In this paper, a sensitive, selective and rapid enzyme immunoassay of ELISA based on polyclonal antibody for detecting butyl benzyl phthalate (BBP) was developed and applied in the environmental water and soil samples. The hapten of BBP was synthesized, then applied to prepare artificial antigen and produce polyclonal antibody capable of specific recognizing BBP. From the optimal standard curve of ELISA for BBP, the values of LOD (limit of detection, IC10) and IC50 were 2.5 and 79.4 ng/mL, respectively. The ELISA showed high specificity, with the cross-reactivity toward BBP analogs < 9.6%. The satisfactory accuracy and precision were demonstrated by the recoveries of 76-116% and coefficient of variations (CVs) of 4.7-13.7%. Furthermore, BBP contamination was investigated at 3.1-25.2 ng/mL in real water samples and 4.2-76.4 ng/g in real soil samples (with the detection rate of 55% in 20 samples) by the developed ELISA, which also had shown a good correlation with that the results obtained by HPLC. All of this indicated that the developed enzyme immunoassay could be applied for sensitive and selective determination of BBP contamination in the environmental samples. Furthermore, the strategy of BBP hapten synthesis and an alternative method of BBP determination could be provided.

Immunomagnetic bead-based biotin-streptavidin system for highly efficient detection of aflatoxin B1 in agricultural products.

The potential homogeneous assay employing immunomagnetic beads (IMB) has been receiving attention as a screening tool in food-safety control; the method is simple, efficient, and does not require long incubation times or complex separation steps. In this study, a homogeneous immunoassay has been successfully developed and applied in the determination of aflatoxin B1 (AFB1) contamination in agricultural products by coupling IMB and the biotin-streptavidin (BSA) (BSA-IMB) system. Under optimal conditions, the limit of detection (LOD, IC10), half-maximal inhibition concentration (IC50) and detection range (IC20-IC80) of BSA-IMB are 0.00579, 0.573 and 0.0183-17.9 ng mL-1, respectively, for AFB1. The detection of AFB1 by BSA-IMB can be achieved in 40 min (ELISA needs at least 180 min). The cross-reactivities of BSA-IMB with its analogues are negligible (<3.82%); these results indicate high selectivity. The spiked recoveries are in the range from 89.6 to 118.2% with relative standard deviations (RSDs) of 3.4 to 13.2% for AFB1 in agricultural product samples. Furthermore, the results of BSA-IMB for authentic samples show reliability and high correlation of 0.9928 with an HPLC-fluorescence detector. The proposed BSA-IMB system is demonstrated to be a satisfactory tool for homogeneous, efficient, sensitive, and alternative detection of AFB1 in a wide detection range for agricultural product samples.

Toxic effect and mechanism of four ionic liquids on seedling taproots of Arabidopsis thaliana.

Arabidopsis thaliana was selected as model organisms to investigate the toxic effect and mechanism of four kinds of imidazolium and pyridinium ionic liquids (ILs) on plant seedling taproots. After exposure to ILs, the growth of seedling taproots was significantly inhibited in a dose-dependent manner. The toxicity of ILs on seedling taproots was [Bmim][BF4] > [Bmpy][BF4] > [Bmim][Br] > [Bmpy][Br]. The reduction of seedling root cell vitality, aggravation of seedling root cell death, and repression of gravitropic growth responses were observed. The amounts of H2O2 and ROS in seedlings were enhanced with increasing concentrations of ILs. Moreover, the expression levels of cdc2a and pcna1 genes were decreased after exposure to ILs. Our results suggest that ILs can induce the overproduction of ROS in A. thaliana seedling taproots and thus cause oxidative damage to seedling taproots. Meanwhile, ILs alter the expression patterns of two cell cycle-related genes and hence cause the seedling taproot growth inhibition. This work provides an integrated understanding of the toxic effect and mechanism of ILs on A. thaliana seedlings at the molecular and physiological level and also provides theoretical basis and reference for the environmental safety evaluation of ILs, prior to their widespread use and release. Graphical abstract ᅟ.

[Research of gene expression profile of liver tissue in rat sepsis model].

OBJECTIVE: To screen differentially expressed genes of liver tissue in rat sepsis model and analyze them in terms of functions. METHODS: Thirty male Wistar rats were randomly divided into model group and blank control group with 15 rats in each group. Cecal ligation and puncture (CLP) was used to reproduce rat sepsis model, gene expression profile microarray that contains 4 096 rat cDNA clones was used to detect the change in gene expression pattern of rat liver tissue 24 hours after CLP, then differentially expressed genes that high correlated to sepsis were screened, and the functions of these genes were analyzed by means of related computer software. RESULTS: Compared to the controls, gene expression of 522 genes in rat sepsis model were changed 24 hours after CLP, accounting for 12.7%, among them 244 gene expression down-regulated, and 278 gene expression up-regulated. CONCLUSION: Multiple organ dysfunction syndrome (MODS) induced by sepsis involves to a series of gene differential expressions, such as cell cycle and control related genes, cell apoptosis genes, immunity related genes, genes concerning energy metabolism, blood system related genes, cancer related genes, growth factor genes, acute stress reaction related genes etc. Gene microarray technique can be used to comprehensively study gene expression profile in rat sepsis model, in order to find new research objectives and gene therapy strategies for sepsis.

Influence of magnesium ion on the binding of p53 DNA-binding domain to DNA-response elements.

Site-specific recognition and DNA-binding activity of p53 are crucial for its tumour suppressor function. Previous reports have shown that metal ions can affect the specific recognition and DNA-binding activity of p53DBD. Here we firstly report that magnesium ion can bind to the protein and influence its DNA-binding activity. To elucidate the nature and the effect of metal ions in the reaction chemistry, we utilized endogenous tryptophan fluorescence to quantitate the interaction between p53DBD and metal ions. The K(a) value for the binding of Mg(2+) to the protein is 1.88 x 10(3) M(-1). Analysis of the CD data clearly suggested that the binding of magnesium ion induced a subtle conformational change rather than a radical modification of the overall protein architecture. Based on the results of electrophoretic mobility shift assays and fluorescence experiments, we concluded that the binding of Mg(2+) significantly stimulated the binding of the protein to DNA in a sequence-independent manner, which differed from that of zinc ions in a sequence-specific manner. Based on these results and the fact that Mg(2+) exists at relatively high concentration in the cell, we propose that Mg(2+) is one of potential factors to affect or regulate the transactivation of p53.

Effect of metal ion on the structural stability of tumour suppressor protein p53 DNA-binding domain.

The tumour suppressor protein p53 is a sequence-specific transcription factor that coordinates one molecule of zinc in the core domain. In our recent study, magnesium can also bind to the p53DBD and enhance its DNA-binding activity. In this study, a systematic analysis of the conformation and stability changes induced by these two metal ions was reported. The spectra of protein intrinsic fluorescence were used to measure the equilibrium unfolding of the p53DBD protein. The stability against chemical denaturation increased in the order apo < Mg(2+) < Zn(2+). The thermal stability monitored by DSC scans showed that the binding of metal ions to p53DBD increased the thermal stability of the protein. To explore additional information of structural changes after the binding of metal ions, we used the fluorescent probes to evaluate the hydrophobic surface exposure. The results established that metal ions binding increased hydrophobic exposure on the surface of p53DBD. Analysis of acrylamide quenching experiments revealed that the binding of metal ions to p53DBD induced a structural modification of the protein and this change provided significant protection against acrylamide quenching. Overall, the present results indicated that p53DBD underwent a conformational change upon the binding of metal ions, which was characterized by an increased stability of the protein.

Nanoparticles from block copolymer encapsulating Re(phen) complexes as bifunctional agents for cell imaging and gene transfection.

Luminescent bifunctional core-shell nanoparticles were successfully constructed from block copolymer encapsulating Re(phen) complexes for simultaneous cell imaging and gene transfection in living cells.