Degradation mechanisms and toxicity determination of bisphenol A by FeOx-activated peroxydisulfate under ultraviolet light.

Ultraviolet light (UV)-assisted advanced oxidation processes (AOPs) are commonly used to degrade organic contaminants. However, this reaction system's extensive comprehension of the degradation mechanisms and toxicity assessment remains inadequate. This study focuses on investigating the degradation mechanisms and pathways of bisphenol A (BPA), generation of reactive oxygen species (ROS), and toxicity of degradation intermediates in UV/PDS/ferrous composites (FeOx) systems. The degradation rate of BPA gradually increased from the initial 11.92% to 100% within 120 min. Sulfate radicals (SO4.-), hydroxyl radicals (.OH), superoxide anions (O2.-), and singlet oxygen (1O2) were the primary factors in the photocatalytic degradation of BPA in the UV/PDS/FeOx systems. The main reactions of BPA in this system were deduced to be ß-bond cleavage, hydroxyl substitution reaction, hydrogen bond cleavage, and oxidation reaction. A trend of decreasing toxicity for the degradation intermediates of BPA was observed according to the toxicity investigations. The efficient degradation of BPA in UV/PDS/FeOx systems provided theoretical data for AOPs, which will improve the understanding of organic contaminants by FeOx in natural industry wastewater.

Degradation of triclosan by peroxydisulfate/peroxomonosulfate binary oxidants activation under thermal conditions: Efficiency and mechanism.

Peroxydisulfate (PDS) and peroxymonosulfate (PMS) could be efficiently activated by heat to generate reactive oxygen species (ROS) for the degradation of organic contaminants. However, defects including the inefficiency treatment and pH dependence of monooxidant process are prominent. In this study, synergy of heat and the PDS-PMS binary oxidant was studied for efficient triclosan (TCS) degradation and apply in rubber wastewater. Under different pH values, the degradation of TCS followed pseudo-first-order kinetics, the reaction rate constant (kobs) value of TCS in heat/PDS/PMS system increased from 1.8 to 4.4 fold and 6.8-49.1 fold when compared to heat/PDS system and heat/PMS system, respectively. Hydroxyl radicals (·OH), sulfate radicals (SO4·-) and singlet oxygen (1O2) were the major ROS for the degradation of TCS in heat/PDS/PMS system. In addition, the steady-state concentrations of ·OH/1O2 and SO4·-/·OH/1O2 increased under acidic conditions and alkaline conditions, respectively. It was concluded that the pH regulated the ROS for degradation of TCS in heat/PDS/PMS system significantly. Based on the analysis of degradation byproducts, it was inferred that the dechlorination, hydroxylation and ether bond breaking reactions occurred during the degradation of TCS. Moreover, the biological toxicity of the ten byproducts was lower than that of TCS was determined. Furthermore, the heat/PDS/PMS system is resistant to the influence of water substrates and can effectively improve the water quality of rubber wastewater. This study provides a novel perspective for efficient degradation of TCS independent of pH in the heat/PDS/PMS system and its application of rubber wastewater.

Identification and characterization of a chitin deacetylase from a metagenomic library of deep-sea sediments of the Arctic Ocean.

BACKGROUND: The chemical and biological compositions of deep-sea sediments are interesting because of the underexplored diversity when it comes to bioprospecting. The special geographical location and climates make Arctic Ocean a unique ocean area containing an abundance of microbial resources. METHODS: A metagenomic library was constructed based on the deep-sea sediments of Arctic Ocean. Part of insertion fragments of this library were sequenced. A chitin deacetylase gene, cdaYJ, was identified and characterized. RESULTS: A metagenomic library with 2750 clones was obtained and ten clones were sequenced. Results revealed several interesting genes, including a chitin deacetylase coding sequence, cdaYJ. The CdaYJ is homologous to some known chitin deacetylases and contains conserved chitin deacetylase active sites. CdaYJ protein exhibits a long N-terminal and a relative short C-terminal. Phylogenetic analysis revealed that CdaYJ showed highest homology to CDAs from Alphaproteobacteria. The cdaYJ gene was subcloned into the pET-28a vector and the recombinant CdaYJ (rCdaYJ) was expressed in Escherichia coli BL21 (DE3). rCdaYJ showed a molecular weight of 43kDa, and exhibited deacetylation activity by using p-nitroacetanilide as substrate. The optimal pH and temperature of rCdaYJ were tested as pH7.4 and 28°C, respectively. CONCLUSIONS: The construction of metagenomic library of the Arctic deep-sea sediments provides us an opportunity to look into the microbial communities and exploiting valuable gene resources. A chitin deacetylase CdaYJ was identified from the library. It showed highest deacetylation activity under slight alkaline and low temperature conditions. CdaYJ might be a candidate chitin deacetylase that possesses industrial and pharmaceutical potentials.

Determination of glutathione in apoptotic SMMC-7221 cells induced by xylitol selenite using capillary electrophoresis.

OBJECTIVE: To determine the glutathione (GSH) content in a human hepatoma cell line (SMMC-7221) treated with xylitol/selenite, providing a part of an investigation of its anti-cancer mechanisms. RESULTS: The nuclei of SMMC-7221 cells were stained with Hoechst 33258 in an apoptosis assay, and their morphology subsequently changed from circular to crescent shape. The calibration curve (r(2) = 0.992) was established, and GSH content markedly decreased after treated with 0.5 and 1 mg xylitol/selenite l(-1) for 12, 36 and 60 h (12 h: from 95.57 ± 19.57 to 29.09 ± 7.74 and 24.27 ± 11.15; 36 h: from 70.73 ± 11.35 to 19.54 ± 6.39 and 9.35 ± 6.69; 60 h: from 72.63 ± 16.94 to 7.432 ± 3.84 and 0). The depletion rate of GSH was more related to the concentration of xylitol/selenite than the treatment time (from 69.95 ± 1.87 to 100 % vs. 0.22 ± 0.2 to 100 %). CONCLUSIONS: Xylitol/selenite is a promising anti-cancer drug to induce apoptosis in SMMC-7221 cells. It may regulate the apoptosis through the co-action of multiple mechanisms related to GSH depletion.

Substrate specificity and biochemical characterization of an adenylation domain from an obligate marine actinomycete.

Salinispora arenicola CNS-205 was a first-isolated obligate marine actinomycete. A gene (sare0357), annotated as ''amino acid adenylation domain'' located on the genome of Salinispora arenicola CNS-205, was cloned and characterized. The recombinant target protein Sare0357 was expressed in E. coli. Sare0357 specifically recognized and activated tryptophan (Trp) and phenylalanine (Phe). The basic kinetic parameters of Sare0357 for Trp were K m = 0.04 mM, V max = 2.1 µM/min, k cat = 14.2 min(-1), and for Phe were K m = 0.03 mM, V max = 1.6 µM/min, kcat = 10.4 min(-1). Our data elucidated Sare0357 biological role and biochemical properties as a Trp and Phe-activating adenylation domain.

Enhanced liver functions of HepG2 cells in the alginate/xyloglucan scaffold.

A scaffold provides a framework and initial support for the cells to attach, proliferate and differentiate, and form an extracellular matrix (ECM) in tissue engineering. Here, xyloglucan (XG) was used as a new synthetic ECM for HepG2 cell attachment in alginate capsules. The effects of XG on HepG2 cells on adherent behavior, albumin secretion, ammonia elimination, cell proliferation and gene expression of Connexin 32 and epithelial-cadherin were investigated. Xyloglucan could also promote the HepG2 cell-matrix interactions and the cell clusters formation of HepG2 cells in three dimensional scaffold, thus enhance the liver-specific functions in the three-dimensional space.

Monoclonal antibodies directed against VP7 protein of human group B rotavirus.

The aim of this study was to prepare and identify a monoclonal antibody that binds the viral proteins 7 (VP7 protein) of human group B rotavirus (GBRV) and to describe its immunologic characterization. Human group B rotavirus vp7 gene was successfully ligated into pGEX-KG vector and transformed into Escherichia coli TOP10 cells. The glutathione S-transferases (GST)-fusion protein GST-VP7 was induced by Isopropyl ß-D-1-thiogalactopyranoside (IPTG) and immediately purified to immunize BALB/c mice. Splenocytes were then prepared from the immunized mouse and fused with SP2/0 myeloma cell line. In the end we obtained one positive hybridoma cell line stably secreting monoclonal antibody against GST-VP7 protein by indirect enzyme-linked immunosorbent assay (ELISA) and limiting dilution. The production of the monoclonal antibody against GBRV will benefit the further study of GBRV's structures and functions and also lay a solid foundation for the research of disease prevention, clinical diagnosis, and treatment.

Crystal structure of human Intersectin-2L C2 domain.

Intersectin-2L (ITSN-2L) is a long isoform of ITSN family, which is a multimodule scaffolding protein functioning in membrane-associated molecular trafficking and signal transduction pathways. ITSN-2L possesses a carboxy-terminal extension encoding a Dbl homology domain (DH), a pleckstrin homology domain (PH) and a C2 domain, suggesting that it could act as a guanine nucleotide exchange factor for Rho-like GTPases. But the role of C2 domain is obscure in this process. Here we report the crystal structure of human ITSN-2L C2 domain at 1.56Å resolution. The sequence and structural alignment of ITSN-2L C2 domain with other members of C2 domain protein family indicate its vital cellular roles in membrane trafficking, the generation of lipid-second messengers and activation of GTPases. Moreover, our data show the possible roles of ITSN-2L C2 domain in regulating the activity of Cdc42.

Dynamic sieving capillary electrophoresis analysis of xylitol selenite-induced apoptosis in SMMC-7221 cells.

DNA ladder fragments, regarded as a biochemical hallmark of apoptosis, have been separated quickly and successfully by capillary electrophoresis. Inter-nucleosomal DNA fragmentations induced by xylitol selenite were determined for the first time, while hydroxypropylmethylcellulose (HPMC) was served as the sieving matrix in dynamic sieving capillary electrophoresis. The calibration curve (r(2) = 0.991) was established and multiples of two different nucleosomes (140 and 180 bp) were formed in the presence of xylitol selenite. Selenium compounds inhibited carcinogenesis in animal models, SMMC-7221 cells and several other cells by increasing apoptosis. The described method was useful in elucidating the anticancer activities of xylitol selenite and other selenium compounds, which was more effective to detect small fragments than slab gel electrophoresis.

[Association of Hind RFLP in lipoprotein lipase gene with type 2 diabetes].

We examined the association of a Hind RFLP (restriction fragment length polymorphism) in the lipoprotein lipase (LPL) gene with type 2 diabetes (T2DM) in Chinese Han population in Hubei Province. Genotypes were determined by PCR-RFLP in 102 controls and 264 T2DM patients using sib-pair and unrelated case-control designs. The frequencies of the H+ allele and H+H+ genotype for patients were significantly higher than those for controls (H+: 76.9% vs 69.1%, P < 0.05; H+H+: 59.8% vs 52%, P < 0.05). When all subjects were grouped as designed, the H+ allele and H+H+ genotype for sib patients were significantly higher than those for sib controls (H+: 81.5% vs 67.8%, P < 0.05; H+H+: 68.5% vs 50.7%, P < 0.05), while there were no significant differences in controls and random patients (P>0.05). Logistic regression analysis suggested that risk factors for T2DM was fasting plasma glucose and LPL genotypes, with individuals with the H+H+ genotype doubling their risk for T2DM as compared to those with the H+H- and H-H- genotypes (95% CI: 1.0363.840, P < 0.05). These data suggest that the Hind RFLP in the LPL gene is associated with T2DM risk in Chinese Han population in Hubei Province, and the H+ allele may serve as a genetic risk factor of T2DM.

[A molecular phylogeny of Shennongjia white bear based on mitochondrial cytochrome b gene sequence].

The phylogenetic relationship of Shennongjia white bear has been an open question. Total DNA was extracted and sequenced from hair and feces of Shennongjia white bear. Based on the partial Cyt b gene sequence obtained from the samples, the authors aligned them using the Clustal W software program. The MEGA software was used to analyze the divergences and base substitutions of the partial Cyt b gene among the 11 species: Shennongjia white bear, Selenarctos thibetanus, Euarctos americanus, Helarctos malayanus, Ursus arctos, Thalarctos maritimus, Melursus ursinus, Procyon lotor, Ailuropoda melanoleuca, Ailurus fulgens and Tremarctos ornatus. The phylogenetic trees constructed by multiple methods (NJ and MP) supported nearly the same topology. Our molecular results show that the sequence divergence between Shennongjia white bear and Asiatic black bear (Selenarctos thibetanus) is lower than that between other species.

[Whole sequence analysis of brain-derived neurotrophic factor gene in Asiatic Black Bear through faecal sampling].

Using our lab's improved protocol for faecal DNA extraction, the entire 753-bp DNA coding sequence of the nuclear brain-derived neurotrophic factor (BDNF) gene was cloned for the first time from Asiatic Black Bear Selenarctos thibetanus faecal samples with primers based on the reported sequence of the Malayan Bear BDNF gene. Hair was used as a positive control and the experiments were repeated several times to obtain reliable and identical results. Sequence analysis showed that the BDNF gene of Asiatic Black Bear was highly conserved compared to those of human and giant panda, with an identity of 94.5% and 98.9%, respectively. The deduced amino acid sequence of the mature protein was found to be identical to those of all the reported mammalians. According to gene sequence alignment, the giant panda appeared to be phylogenetically closer to Asiatic Black Bear than the lesser panda. This study represents the first time that a non-invasive method such as faecal sampling was used to analyze a functional nuclear BDNF gene of Asiatic Black Bear. It will not only provide important reference for the conservation and breeding of Asiatic Black Bear and open up new avenues of non-invasive sampling in the study of endangered wildlife, but also provide another molecular evidence for the study of relationship of Asiatic Black Bear and its related species.