A direct electrode-driven P450 cycle for biocatalysis

The large potential of redox enzymes to carry out formation of high value organic compounds motivates the search for innovative strategies to regenerate the cofactors needed by their biocatalytic cycles. Here, we describe a bioreactor where the reducing power to the cycle is supplied directly to purified cytochrome CYP101 (P450cam; EC 1.14.15.1) through its natural redox partner (putidaredoxin) using an antimony-doped tin oxide working electrode. Required oxygen was produced at a Pt counter electrode by water electrolysis. A continuous catalytic cycle was sustained for more than 5 h and 2,600 enzyme turnovers. The maximum product formation rate was 36 nmol of 5-exo-hydroxycamphor/nmol of CYP101 per min.

Contribution of parental blood pressures to association between low birth weight and adult high blood pressure: cross sectional study

Objective: To examine the possibility that low birth weight is a feature of the inherited predisposition to high blood pressure.

Does moderate alcohol consumption affect fertility? Follow up study among couples planning first pregnancy

Objective: To examine the effect of alcohol consumption on the probability of conception.

The University of Minnesota Biocatalysis/Biodegradation Database: emphasizing enzymes

The University of Minnesota Biocatalysis/Biodegradation Database (UM-BBD, http://umbbd.ahc.umn.edu/) provides curated information on microbial catabolic enzymes and their organization into metabolic pathways. Currently, it contains information on over 400 enzymes. In the last year the enzyme page was enhanced to contain more internal and external links; it also displays the different metabolic pathways in which each enzyme participates. In collaboration with the Nomenclature Commission of the International Union of Biochemistry and Molecular Biology, 35 UM-BBD enzymes were assigned complete EC codes during 2000. Bacterial oxygenases are heavily represented in the UM-BBD; they are known to have broad substrate specificity. A compilation of known reactions of naphthalene and toluene dioxygenases were recently added to the UM-BBD; 73 and 108 were listed respectively. In 2000 the UM-BBD is mirrored by two prestigious groups: the European Bioinformatics Institute and KEGG (the Kyoto Encyclopedia of Genes and Genomes). Collaborations with other groups are being developed. The increased emphasis on UM-BBD enzymes is important for predicting novel metabolic pathways that might exist in nature or could be engineered. It also is important for current efforts in microbial genome annotation.

Differential Control of Xanthophylls and Light-Induced Stress Proteins, as Opposed to Light-Harvesting Chlorophyll a/b Proteins, during Photosynthetic Acclimation of Barley Leaves to Light Irradiance

Barley (Hordeum vulgare L.) plants were grown at different photon flux densities ranging from 100 to 1800 μmol m−2 s−1 in air and/or in atmospheres with reduced levels of O2 and CO2. Low O2 and CO2 partial pressures allowed plants to grow under high photosystem II (PSII) excitation pressure, estimated in vivo by chlorophyll fluorescence measurements, at moderate photon flux densities. The xanthophyll-cycle pigments, the early light-inducible proteins, and their mRNA accumulated with increasing PSII excitation pressure irrespective of the way high excitation pressure was obtained (high-light irradiance or decreased CO2 and O2 availability). These findings indicate that the reduction state of electron transport chain components could be involved in light sensing for the regulation of nuclear-encoded chloroplast gene expression. In contrast, no correlation was found between the reduction state of PSII and various indicators of the PSII light-harvesting system, such as the chlorophyll a-to-b ratio, the abundance of the major pigment-protein complex of PSII (LHCII), the mRNA level of LHCII, the light-saturation curve of O2 evolution, and the induced chlorophyll-fluorescence rise. We conclude that the chlorophyll antenna size of PSII is not governed by the redox state of PSII in higher plants and, consequently, regulation of early light-inducible protein synthesis is different from that of LHCII.

Overexpression of Iron Superoxide Dismutase in Transformed Poplar Modifies the Regulation of Photosynthesis at Low CO2 Partial Pressures or Following Exposure to the Prooxidant Herbicide Methyl Viologen1

Chloroplast-targeted overexpression of an Fe superoxide dismutase (SOD) from Arabidopsis thaliana resulted in substantially increased foliar SOD activities. Ascorbate peroxidase, glutathione reductase, and monodehydroascorbate reductase activities were similar in the leaves from all of the lines, but dehydroascorbate reductase activity was increased in the leaves of the FeSOD transformants relative to untransformed controls. Foliar H2O2, ascorbate, and glutathione contents were comparable in all lines of plants. Irradiance-dependent changes in net CO2 assimilation and chlorophyll a fluorescence quenching parameters were similar in all lines both in air (21% O2) and at low (1%) O2. CO2-response curves for photosynthesis showed similar net CO2-exchange characteristics in all lines. In contrast, values of photochemical quenching declined in leaves from untransformed controls at intercellular CO2 (Ci) values below 200 μL L−1 but remained constant with decreasing Ci in leaves of FeSOD transformants. When the O2 concentration was decreased from 21 to 1%, the effect of FeSOD overexpression on photochemical quenching at limiting Ci was abolished. At high light (1000 μmol m−2 s−1) a progressive decrease in the ratio of variable (Fv) to maximal (Fm) fluorescence was observed with decreasing temperature. At 6oC the high-light-induced decrease in the Fv/Fm ratio was partially prevented by low O2 but values were comparable in all lines. Methyl viologen caused decreased Fv/Fm ratios, but this was less marked in the FeSOD transformants than in the untransformed controls. These observations suggest that the rate of superoxide dismutation limits flux through the Mehler-peroxidase cycle in certain conditions.

Moderate increase in histone acetylation activates the mouse mammary tumor virus promoter and remodels its nucleosome structure.

The mouse mammary tumor virus (MMTV) promoter is regulated by steroid hormones through a hormone-responsive region that is organized in a positioned nucleosome. Hormone induction leads to a structural change of this nucleosome which makes its DNA more sensitive to cleavage by DNase I and enables simultaneous binding of all relevant transcription factors. In cells carrying either episomal or chromosomally integrated MMTV promoters, moderate acetylation of core histones, generated by treatment with low concentrations of the histone deacetylase inhibitors sodium butyrate or trichostatin A, enhances transcription from the MMTV promoter in the absence of hormone and potentiates transactivation by either glucocorticoids or progestins. At higher concentrations, histone deacetylase inhibitors reduce basal and hormone induced MMTV transcription. Inducing inhibitor concentrations lead to the same type of nucleosomal DNase I hypersensitivity as hormone treatment, suggesting that moderate acetylation of core histone activates the MMTV promoter by mechanisms involving chromatin remodeling similar to that generated by the inducing hormones.

Family firms and the great crisis: evidence from the italian case

Few studies have analyzed how family firms have acted during the global great crisis in comparison to their nonfamily counterparts. This paper tries to fill this gap on the basis of the Italian experience using a sample of almost 4,500 for 2007 and 2010. We study whether family control affects labour productivity, labour costs and competitiveness and if the adoption of performance related pay (PRP) reveals an efficacious strategy to mitigate the effects of the crisis and reduce the gap in competitiveness with respect to nonfamily firms. We use quantile regression techniques to test the heterogeneous role of PRP and pay attention for its possible endogeneity. We have observed that after the outburst of the crisis, the distance in terms of competitiveness of family firms with respect to their nonfamily counterparts has been amplified. We also find that family firms may take advantage from the adoption of incentive schemes, such as PRP, to encourage commitment and motivation from their employees more than nonfamily firms. The positive role of PRP on labour productivity, coupled with a moderate influence of these schemes on wage premiums, enable them to regain competitiveness also under hostile pressures, as those featuring the strong global crisis.

Toric implantable collamer lens for moderate to high myopic astigmatism: 3-year follow-up

Background To evaluate the 3-year clinical outcomes after toric implantable collamer lens (ICL) implantation for the management of moderate to high myopic astigmatism. Methods Thirty-four eyes of 20 patients who underwent toric ICL implantation were reviewed. All eyes completed 3-year follow-up. Uncorrected (UDVA) and corrected (CDVA) distance LogMAR visual acuities, refraction, endothelial cell density (ECD), and surgical complications were evaluated. Vectorial analysis of astigmatic correction was also done. Results A significant improvement in UDVA, CDVA, manifest spherical and cylindrical refraction was observed at 1 week and remained stable after 3 years. Twenty-six eyes (76.5 %) gained lines of CDVA, and two eyes (5.9 %) showed a loss of 1 line of CDVA. The spherical equivalent (SE) was within ±0.50 D of emmetropia in 18 eyes (52.9 %) and within ±1.00 D in 28 eyes (82.4 %). Differences between target-induced astigmatism (TIA) and surgically-induced astigmatism (SIA) were statistically significant (p < 0.01), and a trend to undercorrection of the refractive astigmatism was present after 3 years. The magnitude of flattening effect (FE) was found to be significantly lower than the magnitude of TIA (p < 0.01). The magnitude of the torque vector was always positive, with a value below 0.50 D in all cases. No vision-threatening complications were observed during the follow-up. Conclusion Toric ICL implantation is an effective and safe surgical option that provides a relatively predictable and stable refractive correction of myopic astigmatism. Further improvements are needed to minimize the degree of undercorrection.

Hydrogen Peroxide in Biocatalysis. A Dangerous Liaison

Hydrogen peroxide is a substrate or side-product in many enzyme-catalyzed reactions. For example, it is a side-product of oxidases, resulting from the re-oxidation of FAD with molecular oxygen, and it is a substrate for peroxidases and other enzymes. However, hydrogen peroxide is able to chemically modify the peptide core of the enzymes it interacts with, and also to produce the oxidation of some cofactors and prostetic groups (e.g., the hemo group). Thus, the development of strategies that may permit to increase the stability of enzymes in the presence of this deleterious reagent is an interesting target. This enhancement in enzyme stability has been attempted following almost all available strategies: site-directed mutagenesis (eliminating the most reactive moieties), medium engineering (using stabilizers), immobilization and chemical modification (trying to generate hydrophobic environments surrounding the enzyme, to confer higher rigidity to the protein or to generate oxidation-resistant groups), or the use of systems capable of decomposing hydrogen peroxide under very mild conditions. If hydrogen peroxide is just a side-product, its immediate removal has been reported to be the best solution. In some cases, when hydrogen peroxide is the substrate and its decomposition is not a sensible solution, researchers coupled one enzyme generating hydrogen peroxide “in situ” to the target enzyme resulting in a continuous supply of this reagent at low concentrations thus preventing enzyme inactivation. This review will focus on the general role of hydrogen peroxide in biocatalysis, the main mechanisms of enzyme inactivation produced by this reactive and the different strategies used to prevent enzyme inactivation caused by this “dangerous liaison”.

The Use of Nudges in Exergames to Moderate Player Exertion

Exergames are digital games with a physical exertion component. Exergames can help motivate fitness in people not inclined toward exercise. However, players of exergames sometimes over-exert, risking adverse health effects. These players must be told to slow down, but doing so may distract them from gameplay and diminish their desire to keep exercising. In this thesis we apply the concept of nudges—indirect suggestions that gently push people toward a desired behaviour—to keeping exergame players from over-exerting. We describe the effective use of nudges through a set of four design principles: natural integration, comprehension, progression, and multiple channels. We describe two exergames modified to use nudges to persuade players to slow down, and describe the studies evaluating the use of nudges in these games. PlaneGame shows that nudges can be as effective as an explicit textual display to control player over-exertion. Gekku Race demonstrates that nudges are not necessarily effective when players have a strong incentive to over-exert. However, Gekku Race also shows that, even in high-energy games, the power of nudges can be maintained by adding negative consequences to the nudges. We use the term "shove" to describe a nudge using negative consequences to increase its pressure. We were concerned that making players slow down would damage their immersion—the feeling of being engaged with a game. However, testing showed no loss of immersion through the use of nudges to reduce exertion. Players reported that the nudges and shoves motivated them to slow down when they were over-exerting, and fit naturally into the games.