75 research outputs found

    Physicochemical Changes of Few-Layer Graphene in Peroxidase-Catalyzed Reactions: Characterization and Potential Ecological Effects

    No full text
    The environmental implications of graphene have received much attention, however, little is known about how graphene affects or may be affected by the enzymatic reactions that are critically involved in natural organic matter transformation processes. We conducted experiments to examine the role of few-layer graphene (FLG) in the reaction system of tetrabromobisphenol A (TBBPA) mediated by horseradish peroxidase (HRP). We found that TBBPA was transformed by HRP into two products that were likely formed from coupling of two TBBPA radicals via interaction of an oxygen atom on one radical and a propyl-substituted aromatic carbon atom on the other. Presence of FLG greatly increased the reaction rate by protecting HRP from inactivation. Direct reactions between TBBPA radicals and FLG were unequivocally evidenced using <sup>14</sup>C labeling and the characteristic photoelectron response of bromine contained in TBBPA. The thickness, size, and aggregation profile of FLG was modified by the reaction as shown by multiple characterization tools. Assessment using <i>Daphnia magna</i> revealed a substantial decrease in the bioaccumulation and toxicity of the FLG after being modified. The data provides the first evidence that FLG can be modified in HRP-mediated reactions and indicates that such modifications may have strong implications in its ecological effects

    Physicochemical Changes of Few-Layer Graphene in Peroxidase-Catalyzed Reactions: Characterization and Potential Ecological Effects

    No full text
    The environmental implications of graphene have received much attention, however, little is known about how graphene affects or may be affected by the enzymatic reactions that are critically involved in natural organic matter transformation processes. We conducted experiments to examine the role of few-layer graphene (FLG) in the reaction system of tetrabromobisphenol A (TBBPA) mediated by horseradish peroxidase (HRP). We found that TBBPA was transformed by HRP into two products that were likely formed from coupling of two TBBPA radicals via interaction of an oxygen atom on one radical and a propyl-substituted aromatic carbon atom on the other. Presence of FLG greatly increased the reaction rate by protecting HRP from inactivation. Direct reactions between TBBPA radicals and FLG were unequivocally evidenced using <sup>14</sup>C labeling and the characteristic photoelectron response of bromine contained in TBBPA. The thickness, size, and aggregation profile of FLG was modified by the reaction as shown by multiple characterization tools. Assessment using <i>Daphnia magna</i> revealed a substantial decrease in the bioaccumulation and toxicity of the FLG after being modified. The data provides the first evidence that FLG can be modified in HRP-mediated reactions and indicates that such modifications may have strong implications in its ecological effects

    Cloning and Phylogenetic Analysis of <i>Brassica napus</i> L. <i>Caffeic Acid O-Methyltransferase 1</i> Gene Family and Its Expression Pattern under Drought Stress

    No full text
    <div><p>For many plants, regulating lignin content and composition to improve lodging resistance is a crucial issue. Caffeic acid O-methyltransferase (COMT) is a lignin monomer-specific enzyme that controls S subunit synthesis in plant vascular cell walls. Here, we identified 12 <i>BnCOMT1</i> gene homologues, namely <i>BnCOMT1-1</i> to <i>BnCOMT1-12</i>. Ten of 12 genes were composed of four highly conserved exons and three weakly conserved introns. The length of intron I, in particular, showed enormous diversification. Intron I of homologous <i>BnCOMT1</i> genes showed high identity with counterpart genes in <i>Brassica rapa</i> and <i>Brassica oleracea</i>, and intron I from positional close genes in the same chromosome were relatively highly conserved. A phylogenetic analysis suggested that <i>COMT</i> genes experience considerable diversification and conservation in <i>Brassicaceae</i> species, and some <i>COMT1</i> genes are unique in the <i>Brassica</i> genus. Our expression studies indicated that <i>BnCOMT1</i> genes were differentially expressed in different tissues, with <i>BnCOMT1-4</i>, <i>BnCOMT1-5</i>, <i>BnCOMT1-8</i>, and <i>BnCOMT1-10</i> exhibiting stem specificity. These four <i>BnCOMT1</i> genes were expressed at all developmental periods (the bud, early flowering, late flowering and mature stages) and their expression level peaked in the early flowering stage in the stem. Drought stress augmented and accelerated lignin accumulation in high-lignin plants but delayed it in low-lignin plants. The expression levels of <i>BnCOMT1s</i> were generally reduced in water deficit condition. The desynchrony of the accumulation processes of total lignin and <i>BnCOMT1</i>s transcripts in most growth stages indicated that <i>BnCOMT1s</i> could be responsible for the synthesis of a specific subunit of lignin or that they participate in other pathways such as the melatonin biosynthesis pathway.</p></div

    The artificial sweetener acesulfame potassium affects the gut microbiome and body weight gain in CD-1 mice

    Get PDF
    <div><p>Artificial sweeteners have been widely used in the modern diet, and their observed effects on human health have been inconsistent, with both beneficial and adverse outcomes reported. Obesity and type 2 diabetes have dramatically increased in the U.S. and other countries over the last two decades. Numerous studies have indicated an important role of the gut microbiome in body weight control and glucose metabolism and regulation. Interestingly, the artificial sweetener saccharin could alter gut microbiota and induce glucose intolerance, raising questions about the contribution of artificial sweeteners to the global epidemic of obesity and diabetes. Acesulfame-potassium (Ace-K), a FDA-approved artificial sweetener, is commonly used, but its toxicity data reported to date are considered inadequate. In particular, the functional impact of Ace-K on the gut microbiome is largely unknown. In this study, we explored the effects of Ace-K on the gut microbiome and the changes in fecal metabolic profiles using 16S rRNA sequencing and gas chromatography-mass spectrometry (GC-MS) metabolomics. We found that Ace-K consumption perturbed the gut microbiome of CD-1 mice after a 4-week treatment. The observed body weight gain, shifts in the gut bacterial community composition, enrichment of functional bacterial genes related to energy metabolism, and fecal metabolomic changes were highly gender-specific, with differential effects observed for males and females. In particular, ace-K increased body weight gain of male but not female mice. Collectively, our results may provide a novel understanding of the interaction between artificial sweeteners and the gut microbiome, as well as the potential role of this interaction in the development of obesity and the associated chronic inflammation.</p></div

    ML phylogenetic tree for Methyltransf_2 domains in COMT proteins.

    No full text
    <p>The phylogenetic tree derived by the ML method with bootstrap analysis (1000 replicates) from alignment of amino acid sequences of Methyltransferase domains predicted in COMT proteins from <i>Arabidopsis</i>, <i>B</i>. <i>rapa</i>, <i>B</i>. <i>oleracea</i>, <i>B</i>. <i>napus</i>, and outgroup using MEGA 6.0 program.</p

    Sequence identity of intron I for <i>BnCOMT1s</i>.

    No full text
    <p>Data on the upper right present the sequence identity regardless of the unmatched regions possibly emerged in either end of two aligned intron sequences, and data on the bottom left present the sequence identity of full-length intron sequences.</p

    ML phylogenetic tree for intron I in Brassicaceae COMT1 genes.

    No full text
    <p>The phylogenetic tree derived by the ML method with bootstrap analysis (1000 replicates) from alignment of gene sequences of intron I from three <i>Brassicaceae</i> species using MEGA 6.0 program.</p

    Total lignin content and spatial expression characteristics of stem specific <i>BnCOMT1s</i> under drought stress.

    No full text
    <p>H1, H2 were high-lignin content materials and L1, L2 were low materials. The grey color represents the drought treatment and blue represents the natural condition. BS, ES, LS, and MS were respectively short for budding stage, early flowering stage, late flowering stage and mature stage.</p

    Self-Assembly of Well-Defined Poly(3-hexylthiophene) Nanostructures toward the Structure‚ÄďProperty Relationship Determination of Polymer Solar Cells

    No full text
    The control of the nanoscale morphology of the active layer is vital to obtaining high-performance polymer solar cells (PSCs). In this study, the effects of the nanowire length on the nanoscale organization of the active layer as well on the final performance of PSCs based on poly­(3-hexylthiophene) (P3HT) and [6,6]-phenyl-C61-butyric acid methyl ester (PCBM) are presented. P3HT nanowires with different lengths were obtained by sonication-assisted self-assembly. The nanowire length increased as the temperature increased during sonication. PSCs based on P3HT nanowires/PCBM blends with different nanowire lengths were fabricated, and their performance was systemically investigated. When the P3HT nanowire length increased, the short-circuit current (<i>J</i><sub>sc</sub>) and fill factor (FF) of the devices were both enhanced, which resulted in a higher performance. Morphological characterization of the active layer showed that the longer P3HT nanowires in the active layer have a higher tendency to form interpenetrating network structures that facilitate the charge transport in the active layer

    Functional gene enrichment analysis showing that functional genes related to carbohydrate metabolism were significantly decreased in Ace-K-treated female mice (p<0.05 for all genes listed here).

    No full text
    <p>Functional gene enrichment analysis showing that functional genes related to carbohydrate metabolism were significantly decreased in Ace-K-treated female mice (p<0.05 for all genes listed here).</p
    • ‚Ķ
    corecore