Iterative oxidation by TET1 is required for reprogramming of imprinting control regions and patterning of mouse sperm hypomethylated regions.

Ten-eleven translocation (TET) enzymes iteratively oxidize 5-methylcytosine (5mC) to generate 5-hydroxymethylcytosine (5hmC), 5-formylcytosine, and 5-carboxylcytosine to facilitate active genome demethylation. Whether these bases are required to promote replication-coupled dilution or activate base excision repair during mammalian germline reprogramming remains unresolved due to the inability to decouple TET activities. Here, we generated two mouse lines expressing catalytically inactive TET1 (Tet1-HxD) and TET1 that stalls oxidation at 5hmC (Tet1-V). Tet1 knockout and catalytic mutant primordial germ cells (PGCs) fail to erase methylation at select imprinting control regions and promoters of meiosis-associated genes, validating the requirement for the iterative oxidation of 5mC for complete germline reprogramming. TET1V and TET1HxD rescue most hypermethylation of Tet1-/- sperm, suggesting the role of TET1 beyond its oxidative capability. We additionally identify a broader class of hypermethylated regions in Tet1 mutant mouse sperm that depend on TET oxidation for reprogramming. Our study demonstrates the link between TET1-mediated germline reprogramming and sperm methylome patterning.

TET1 Catalytic Activity is Required for Reprogramming of Imprinting Control Regions and Patterning of Sperm-Specific Hypomethylated Regions.

DNA methylation erasure is required for mammalian primordial germ cell reprogramming. TET enzymes iteratively oxidize 5-methylcytosine to generate 5-hyroxymethylcytosine (5hmC), 5-formylcytosine, and 5-carboxycytosine to facilitate active genome demethylation. Whether these bases are required to promote replication-coupled dilution or activate base excision repair during germline reprogramming remains unresolved due to the lack of genetic models that decouple TET activities. Here, we generated two mouse lines expressing catalytically inactive TET1 ( Tet1-HxD ) and TET1 that stalls oxidation at 5hmC ( Tet1-V ). Tet1 -/- , Tet1 V/V , and Tet1 HxD/HxD sperm methylomes show that TET1 V and TET1 HxD rescue most Tet1 -/- hypermethylated regions, demonstrating the importance of TET1’s extra-catalytic functions. Imprinted regions, in contrast, require iterative oxidation. We further reveal a broader class of hypermethylated regions in sperm of Tet1 mutant mice that are excluded from de novo methylation during male germline development and depend on TET oxidation for reprogramming. Our study underscores the link between TET1-mediated demethylation during reprogramming and sperm methylome patterning.

Cultivated land multifunctionality in undeveloped peri-urban agriculture areas in China: Implications for sustainable land management.

The spatial planning and sustainable management of peri-urban cultivated land are key aspects of national development in many countries because of the continuing expansion of urban areas and deterioration of agro-ecosystem services. Detailed geo-informational investigation of cultivated land multifunctionality and the spatial interactions and dependencies of these multiple functions is required to inform the currently weak theoretical framework of multifunctionality at the peri-urban scale. Accordingly, the objective of this study was to construct a comprehensive methodology to identify and evaluate cultivated land multifunctionality in a spatial context. Geochemical data were used to measure cultivated land multifunctionality. We evaluated two main functions-the productive function and the ecological function-of an undeveloped peri-urban agriculture (PUA) area in the northern fringe of Changchun City in the black-soil region of northeastern China. For the ecological utilization of PUA areas, tradeoff and synergy analyses of cultivated land multifunctionality and coordinated development under complex land-use patterns were measured using a bivariate local Moran's I method. Results reveal considerable spatial heterogeneity in the two functions, with hotspots or coldspots being found in the PUA area. The productive function presents a less pronounced decreasing trend along the rural-to-urban gradient compared with the ecological function. Tradeoffs and synergies between the productive function and the ecological function occur mainly in the northern (more rural) part of the PUA area, where the spatial spillover effect of urbanization is relatively low. Cultivated land functions are strongly affected by urbanization-induced land-use types, and the coordinated areas of the productive function are generally consistent with those of the ecological function. According to these results, we delineate nine zones of multifunctionality in the studied PUA area. Given the importance of harmonizing cultivated land multifunctionality to manage limited land resources in a sustainable way, application of the GIS- and geochemistry-based multifunctionality evaluation scheme proposed in this study should be used to guide peri-urban spatial planning and land-use management and inform the policy arena concerning the transition of land use in urban peripheries.

Sustainable Plant-Based Biopolymer Membranes for PEM Fuel Cells.

Carboxycellulose nanofibers (CNFs) promise to be a sustainable and inexpensive alternative material for polymer electrolyte membranes compared to the expensive commercial Nafion membrane. However, its practical applications have been limited by its relatively low performance and reduced mechanical properties under typical operating conditions. In this study, carboxycellulose nanofibers were derived from wood pulp by TEMPO oxidation of the hydroxyl group present on the C6 position of the cellulose chain. Then, citric acid cross-linked CNF membranes were prepared by a solvent casting method to enhance performance. Results from FT-IR spectroscopy, 13C NMR spectroscopy, and XRD reveal a chemical cross-link between the citric acid and CNF, and the optimal fuel cell performance was obtained by cross-linking 70 mL of 0.20 wt % CNF suspension with 300 µL of 1.0 M citric acid solution. The membrane electrode assemblies (MEAs), operated in an oxygen atmosphere, exhibited the maximum power density of 27.7 mW cm-2 and the maximum current density of 111.8 mA cm-2 at 80 °C and 100% relative humidity (RH) for the citric acid cross-linked CNF membrane with 0.1 mg cm-2 Pt loading on the anode and cathode, which is approximately 30 times and 22 times better, respectively, than the uncross-linked CNF film. A minimum activation energy of 0.27 eV is achieved with the best-performing citric acid cross-linked CNF membrane, and a proton conductivity of 9.4 mS cm-1 is obtained at 80 °C. The surface morphology of carboxycellulose nanofibers and corresponding membranes were characterized by FIB/SEM, SEM/EDX, TEM, and AFM techniques. The effect of citric acid on the mechanical properties of the membrane was assessed by tensile strength DMA.

Application of Fullerenes as Photosensitizers for Antimicrobial Photodynamic Inactivation: A Review.

Antimicrobial photodynamic inactivation (aPDI) is a newly emerged treatment approach that can effectively address the issue of multidrug resistance resulting from the overuse of antibiotics. Fullerenes can be used as promising photosensitizers (PSs) for aPDI due to the advantages of high triplet state yields, good photostability, wide antibacterial spectrum, and permissibility of versatile functionalization. This review introduces the photodynamic activities of fullerenes and the up-to-date understanding of the antibacterial mechanisms of fullerene-based aPDI. The most recent works on the functionalization of fullerenes and the application of fullerene derivatives as PSs for aPDI are also summarized. Finally, certain remaining challenges are emphasized to provide guidance on future research directions for achieving clinical application of fullerene-based aPDI.

[Risk Zoning of Heavy Metals in a Peri-urban Area in the Black Soil Farmland Based on Agricultural Products].

Agricultural products are a primary pathway for humans to accumulate heavy metals (HMs) via the soil-crop system and should therefore should be included as a crucial part of the food security in our country. Given that previous studies on protection zoning for preventing farmland HM pollution rarely considered agricultural products as a basic element, this study attempted to establish a zoning system for farmland HM prevention, which was based on the perspective of agricultural product pollution. We subsequently took a representative peri-urban area in the black soil region, which was provided with a higher risk of being polluted, as an empirical case. The results indicated that:① the comprehensive quality index of agricultural products (IICQAP) was 1.09, illustrating only a mild HM pollution, with Pb and Ni having the highest accumulation levels; ② the human health risk index (QHI) was 0.61, showing no risk for human health; and ③ the designed zoning method revealed 89.45% of the farmlands to be risk-free at the moment and 10.55% of the farmlands to be under low risk of HM pollution in agricultural products. According to the zoning results, we suggested prioritized protection and an early-warning strategy, respectively, and further recommended prevention methods such as accumulation intervention, crop restructuring, and in-situ passivation. The results served to enrich the theoretical basis for preventing farmland HM pollution, to reinforce the management standards for agricultural products in the black soil region, and also to build a differentiated urban-rural farmland protection system.

Bacillus subtilis extracellular polymeric substances conditioning layers inhibit Escherichia coli adhesion to silicon surfaces: A potential candidate for interfacial antifouling additives.

Biofouling on material surfaces is a ubiquitous problem in a variety of fields. In aqueous environments, the process of biofouling initiates with the formation of a layer of macromolecules called the conditioning layer on the solid-liquid interface, followed by the adhesion and colonization of planktonic bacteria and the subsequent biofilm development and maturation. In this study, the extracellular polymeric substances (EPS) secreted by Bacillus subtilis were collected and used to prepare conditioning layers on inert surfaces. The morphologies and antifouling performances of the EPS conditioning layers were investigated. It was found that the initial adhesion of Escherichia coli was inhibited on the surfaces precoated with EPS conditioning layers. To further explore the underlying antifouling mechanisms of the EPS conditioning layers, the respective roles of two constituents of B. subtilis EPS (γ-polyglutamic acid and surfactin) were investigated. This study has provided the possibility of developing a novel interfacial antifouling additive with the advantages of easy preparation, nontoxicity, and environmental friendliness.

Chitosan-Based Functional Materials for Skin Wound Repair: Mechanisms and Applications.

Skin wounds not only cause physical pain for patients but also are an economic burden for society. It is necessary to seek out an efficient approach to promote skin repair. Hydrogels are considered effective wound dressings. They possess many unique properties like biocompatibility, biodegradability, high water uptake and retention etc., so that they are promising candidate materials for wound healing. Chitosan is a polymeric biomaterial obtained by the deacetylation of chitin. With the properties of easy acquisition, antibacterial and hemostatic activity, and the ability to promote skin regeneration, hydrogel-like functional wound dressings (represented by chitosan and its derivatives) have received extensive attentions for their effectiveness and mechanisms in promoting skin wound repair. In this review, we extensively discussed the mechanisms with which chitosan-based functional materials promote hemostasis, anti-inflammation, proliferation of granulation in wound repair. We also provided the latest information about the applications of such materials in wound treatment. In addition, we summarized the methods to enhance the advantages and maintain the intrinsic nature of chitosan via incorporating other chemical components, active biomolecules and other substances into the hydrogels.

Water-soluble AIE-Active Fluorescent Organic Nanoparticles: Design, Preparation and Application for Specific Detection of Cysteine over Homocysteine and Glutathione in Living Cells.

Water-soluble ratiometric AIE-active fluorescent organic nanoparticles 2OA-FON for the specific sensing of cysteine over other biothiols are reported. The obtained amphiphilic probe included olefin aldehyde as recognizing unit, tetraphenylethylene as fluorescence reporter and lactose moiety as a hydrophilic group. This work provides a general design strategy based on the introduction of a sugar moiety into a hydrophobic AIEgen to develop ratiometric water-soluble fluorescent organic nanoparticles.

Preadsorption of Serum Proteins Regulates Bacterial Infections and Subsequent Macrophage Phagocytosis on Biomaterial Surfaces.

Bacterial infection has been one of the main obstacles for extensive biomedical applications of biomaterial films. Understanding the interactions among macromolecules, cells, and bacteria in the microenvironment located on the film surface at the molecular level is essential for developing antibacterial films. Here we report the distinct influence of several key serum proteins adsorbed on diamond-like carbon (DLC) and traditional Ti films on initial bacterial adhesion, biofilm formation, and corresponding immune responses. Type I collagen, Fn, and IgG were selected as the typical serum proteins. Gram-positive bacterium Staphylococcus epidermidis and Gram-negative bacterium Escherichia coli were used as the model bacteria. Macrophage phagocytosis tests were carried out to examine the impact of adsorbed proteins on the ability of macrophages to clear the adhered pathogens. Results show that it was the specific molecular recognition between adsorbed proteins and bacteria, not the surface physiochemical properties such as surface wettability, surface roughness, and surfaces charge, that decisively affected bacterial adhesion and following biofilm formation. Collagen resisted bacterial adhesion on both DLC and Ti films, even though the molecules exhibited distinct conformations on the two surfaces, whereas for Fn and IgG, the specific molecular recognition was closely related to protein conformations. Fn molecules formed globular aggregates on Ti surfaces that greatly enhanced bacterial adhesion but exhibited a fibril conformation on DLC surfaces that inhibited bacterial adhesion. IgG showed an end-on orientation with free F(ab)2 domains on Ti surfaces, facilitating bacterial adhesion and biofilm formation, while the flattened orientation on DLC films showed little effect on bacterial behaviors. Furthermore, preadsorption of Fn and IgG significantly promoted the phagocytosis ability of macrophages against S. epidermidis and affected the corresponding secretion of inflammatory cytokine. These results would give insights into understanding protein-surface interactions for developing appropriate surface modification techniques for biomaterials with desired anti-inflammatory functions.

Influence of surface topography on bacterial adhesion: A review (Review).

Bacterial adhesion and biofilm formation are ubiquitous undesirable phenomena in the marine industry and the medical industry, usually causing economic losses and serious health problems. Numerous efforts have been made to reduce bacterial adhesion and subsequent biofilm formation, most of which are based on the release of toxic biocides from coatings or substrates. In recent years, surface topography has been found to substantially influence the interaction between bacteria and surfaces. This review summarizes previous work dedicated in searching for the relationship between bacterial adhesion and surface topography in the last eight years, as well as the proposed mechanisms by which surface topographic features interact with bacterial cells. Next, various natural and artificial surfaces with bactericidal surface topography along with their bactericidal mechanisms and efficiency are introduced. Finally, the technologies for constructing antibacterial surfaces are briefly summarized.

A long-acting ß2-adrenergic agonist increases the expression of muscarine cholinergic subtype­3 receptors by activating the ß2-adrenoceptor cyclic adenosine monophosphate signaling pathway in airway smooth muscle cells.

The persistent administration of ß2­adrenergic (ß2AR) agonists has been demonstrated to increase the risk of severe asthma, partly due to the induction of tolerance to bronchoprotection via undefined mechanisms. The present study investigated the potential effect of the long­acting ß2­adrenergic agonist, formoterol, on the expression of muscarinic M3 receptor (M3R) in rat airway smooth muscle cells (ASMCs). Primary rat ASMCs were isolated and characterized following immunostaining with anti­α­smooth muscle actin antibodies. The protein expression levels of M3R and phospholipase C­ß1 (PLCß1) were characterized by western blot analysis and the production of inositol 1,4,5­trisphosphate (IP3) was determined using an enzyme­linked immunosorbent assay. Formoterol increased the protein expression of M3R in rat ASMCs in a time­ and dose­dependent manner, which was significantly inhibited by the ß2AR antagonist, ICI118,551 and the cyclic adenosine monophosphate (cAMP) inhibitor, SQ22,536. The increased protein expression of M3R was positively correlated with increased production of PLCß1 and IP3. Furthermore, treatment with the glucocorticoid, budesonide, and the PLC inhibitor, U73,122, significantly suppressed the formoterol­induced upregulated protein expression levels of M3R and PLCß1 and production of IP3. The present study demonstrated that formoterol mediated the upregulation of M3R in the rat ASMCs by activating the ß2AR­cAMP signaling pathway, resulting in increased expression levels of PLCß1 and IP3, which are key to inducing bronchoprotection tolerance. Administration of glucocorticoids or a PLC antagonist prevented formoterol­induced bronchoprotection tolerance by suppressing the protein expression of M3R.

[Clinical characteristics and prognostic factors of fulminate pancreatitis].

OBJECTIVE: To study the clinical characteristics of fulminate pancreatitis (FP) and analysis the factors related to prognosis of FP. METHODS: Data of 203 patients with severe acute pancreatitis (SAP) admitted to our hospital within 72 h after onset of symptoms from January 2000 to December 2002 were reviewed. FP was defined as presence of organ dysfunction within 72 h after onset of symptoms. 78 patients had FP, 125 patients without organ dysfunction within 72 h after onset of symptoms had common severe acute pancreatitis (CSAP). The clinical characteristics, incidence of organ dysfunction during hospitalization and prognosis between FP and CSAP were compared, then the factors related to prognosis of FP were analysed. RESULTS: The incidences of T >/= 38.5 degrees C, hypoxemia, shock, white cell count >/= 16 x 10(9)/L, serum calcium < 2.0 mmol/L and multiple organ dysfunction syndrome (MODS) in FP were higher than those in CSAP (71.8% vs 39.2%, 83.3% vs 30.4%, 41.0% vs 12.0%, 64.1% vs 30.4%, 68.0% vs 44.8%, 73.1% vs 11.2%, P < 0.05). Impairment degree of pancreas (Balthazar CT severity index) in FP was more serious than that in CSAP (5.78 +/- 0.83 vs 3.12 +/- 0.57, P < 0.05). FP had a higher mortality than CSAP (44.9% vs 8.8%, P < 0.05). In multiple logistic regression analysis, the main predisposing factors to FP were hypoxemia, MODS and Balthazar CT severity index. CONCLUSIONS: FP is characterised by severe systemic inflammatory response, severe pathological changes of pancreas, high incidence of MODS and high mortality. The main predisposing factors to FP were hypoxemia, MODS and Balthazar CT severity index.