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Reactive Oxygen Species (ROS) in the form of H 2 O 2 can act both as physiological signaling molecules as well as damaging agents, depending on their concentration and localization. The downstream biological effects of H 2 O 2 were often studied making use of exogenously added H 2 O 2 , generally as a bolus and at supraphysiological levels. But this does not mimic the continuous, low levels of intracellular H 2 O 2 production by for instance mitochondrial respiration. The enzyme d -Amino Acid Oxidase (DAAO) catalyzes H 2 O 2 formation using d -amino acids, which are absent from culture media, as a substrate. Ectopic expression of DAAO has recently been used in several studies to produce inducible and titratable intracellular H 2 O 2. However, a method to directly quantify the amount of H 2 O 2 produced by DAAO has been lacking, making it difficult to assess whether observed phenotypes are the result of physiological or artificially high levels of H 2 O 2. Here we describe a simple assay to directly quantify DAAO activity by measuring the oxygen consumed during H 2 O 2 production. The oxygen consumption rate (OCR) of DAAO can directly be compared to the basal mitochondrial respiration in the same assay, to estimate whether the ensuing level of H 2 O 2 production is within the range of physiological mitochondrial ROS production. In the tested monoclonal RPE1-hTERT cells, addition of 5 mM d -Ala to the culture media amounts to a DAAO-dependent OCR that surpasses ∼5% of the OCR that stems from basal mitochondrial respiration and hence produces supra-physiological levels of H 2 O 2. We show that the assay can also be used to select clones that express differentially localized DAAO with the same absolute level of H 2 O 2 production to be able to discriminate the effects of H 2 O 2 production at different subcellular locations from differences in total oxidative burden. This method therefore greatly improves the interpretation and applicability of DAAO-based models, thereby moving the redox biology field forward. [Display omitted] • Oxygen consumption rate (OCR) can serve to quantify chemogenetic H 2 O 2 production. • Cellular d -amino acid uptake is a rate-limiting step in DAAO-dependent H 2 O 2 production. • The lethal rate of H 2 O 2 production depends on the subcellular localization of DAAO. • Media Glucose concentration is a key determinant of HyPer7 reduction rates. [ABSTRACT FROM AUTHOR]

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jeem.2009.04.002 Byline: Carmen Arguedas (a), Daan P. van Soest (b)(c) Abstract: Investment subsidies are widely used to induce adoption of new technologies that can lower the (marginal) cost of reducing emissions. To economize on these subsidies, governments would like to distinguish between firms that need to receive a subsidy to adopt a new technology, and firms that would adopt that technology even without subsidies. We show that policies consisting of a menu of emission taxes and investment subsidies can potentially induce firms to self-select. Author Affiliation: (a) Departamento de Analisis Economico, Universidad Autonoma de Madrid, Spain (b) Department of Spatial Economics and IVM, VU University Amsterdam, The Netherlands (c) Department of Economics and CentER, Tilburg University, P.O. Box 90153, 5000 LE Tilburg, The Netherlands Article History: Received 24 May 2007

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.jeem.2008.03.004 Byline: Jetske Bouma (a)(b), Erwin Bulte (b)(c), Daan van Soest (b) Keywords: Social capital; Community-based development; Soil and water conservation; Voluntary cooperation; Economic experiments; Trust games Abstract: Social capital is one of the main determinants of community resource management success. We use the (average) amount sent in a trust game as a measure of social capital in five rural villages in India. Combining these experimental data with household surveys we analyze: (i) how the amount sent is correlated with socio-cultural community characteristics, (ii) how social capital affects community resource management, and (iii) to what extent experimental play is consistent with real on-farm behavior in terms of providing a semi-public good. The results are interesting from a policy perspective, and provide insight into (bridging) the gap between lab experiments and the field. Author Affiliation: (a) Institute for Environmental Studies (IVM), Vrije Universiteit, The Netherlands (b) Department of Economics and CentER, Tilburg University, The Netherlands (c) Development Economics Group, Wageningen University, The Netherlands Article History: Received 15 December 2005

To link to full-text access for this article, visit this link: http://dx.doi.org/10.1016/j.reseneeco.2004.11.002 Byline: Daan P. van Soest Keywords: Environmental taxation; Command-and-control instruments; Dynamic efficiency; Stochasticity Abstract: One of the main considerations in designing environmental policy is the impact of policy instruments on the timing of firms' investment decisions with respect to energy-saving technologies. This paper analyzes the impact of environmental taxes and quotas on the timing of adoption when (i) the rate at which new, improved energy-efficient technologies become available, is uncertain, and (ii) the investment decision is (at least partially) irreversible. We find that neither policy instrument is unambiguously preferred to the other when it comes to stimulating early adoption of new technologies. Author Affiliation: Department of Economics and Center, Tilburg University, P.O. Box 90153, 5000 LE Tilburg, The Netherlands Article History: Received 11 April 2003; Revised 9 July 2004; Accepted 2 November 2004

Stabilization and activation of the p53 tumor suppressor are triggered in response to various cellular stresses, including DNA damaging agents and elevated Reactive Oxygen Species (ROS) like H 2 O 2. When cells are exposed to exogenously added H 2 O 2 , ATR/CHK1 and ATM/CHK2 dependent DNA damage signaling is switched on, suggesting that H 2 O 2 induces both single and double strand breaks. These collective observations have resulted in the widely accepted model that oxidizing conditions lead to DNA damage that subsequently mediates a p53-dependent response like cell cycle arrest and apoptosis. However, H 2 O 2 also induces signaling through stress-activated kinases (SAPK, e.g., JNK and p38 MAPK) that can activate p53. Here we dissect to what extent these pathways contribute to functional activation of p53 in response to oxidizing conditions. Collectively, our data suggest that p53 can be activated both by SAPK signaling and the DDR independently of each other, and which of these pathways is activated depends on the type of oxidant used. This implies that it could in principle be possible to modulate oxidative signaling to stimulate p53 without inducing collateral DNA damage, thereby limiting mutation accumulation in both healthy and tumor tissues. [Display omitted] • Oxidizing conditions can stabilize and activate p53 independent of DNA damage signaling. • Oxidant signaling stablizes p53 through inhibition of protein ubiquitinylation and degradation. • p38 MAPK is required for oxidant signaling-mediated p53 activation. • Both DNA damage signaling and oxidant signaling induces p53-dependent transcription and apoptosis. [ABSTRACT FROM AUTHOR]