32 research outputs found

    Relative gene expression in <i>Fucus vesiculosus</i> in controlled condition (white square) and exposed to UV-B (black square) during 72 hours are presented for <i>pksIII</i> (a), <i>ast6</i> (b), <i>hsp70</i> (c), and <i>vbpo</i> (d).

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    <p>The expression of a gene is normalized to the geometric mean of the expression of 2 reference genes (<i>ef1α</i>, <i>tua</i>) in the same algal sample and to the mean of its expression in the three control algae at each time point. Values represent means of three independent replicates and bars represent the SE. Letters indicate significant difference (LSMEANS 0.05).</p

    Photosynthesis efficiency of <i>Fucus vesiculosus</i> under chronic exposure to UV-B radiation during 4 weeks.

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    <p>The optimal quantum yield (Fv/Fm) of apical parts of <i>F</i>.<i>vesiculosus</i> thalli measured through imaging PAM fluorimetry during exposure to PAR (controls, white losanges) and UV-B condition (black squares).Values represent means of three independent replicates and bars represent the SE. Statistically significant differences (LSMEANS 0.05) between treatments are indicated by stars (*).</p

    X‑ray Diffraction and Density Functional Theory Provide Insight into Vanadate Binding to Homohexameric Bromoperoxidase II and the Mechanism of Bromide Oxidation

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    X-ray diffraction of native bromoperoxidase II (EC 1.11.1.18) from the brown alga <i>Ascophyllum nodosum</i> reveals at a resolution of 2.26 Å details of orthovanadate binding and homohexameric protein organization. Three dimers interwoven in contact regions and tightened by hydrogen-bond-clamped guanidinium stacks along with regularly aligned water molecules form the basic structure of the enyzme. Intra- and intermolecular disulfide bridges further stabilize the enzyme preventing altogether the protein from denaturing up to a temperature of 90 °C, as evident from dynamic light scattering and the on-gel <i>ortho</i>-dianisidine assay. Every monomer binds one equivalent of orthovanadate in a cavity formed from side chains of three histidines, two arginines, one lysine, serine, and tryptophan. Protein binding occurs primarily through hydrogen bridges and superimposed by Coulomb attraction according to thermochemical model on density functional level of theory (B3LYP/6-311++G**). The strongest attractor is the arginine side chain mimic <i>N</i>-methylguanidinium, enhancing in positive cooperative manner hydrogen bridges toward weaker acceptors, such as residues from lysine and serine. Activating hydrogen peroxide occurs in the thermochemical model by side-on binding in orthovanadium peroxoic acid, oxidizing bromide with virtually no activation energy to hydrogen bonded hypobromous acid

    Quantification of soluble phenol contents in semi-purified phlorotannins fractions (mg equivalent phloroglucinol.g<sup>-1</sup> DW) in controlled condition (white square) and exposed to UV-B (black square).

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    <p>Values represent means of three independent replicates and bars represent the SD. Mean with different letters indicate significant difference between all samples along the kinetic (LSMEANS 0.05). Stars (*) indicate significant difference between control and UV-B treatment (LSMEANS 0.05).</p
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