Reduction of hydrogen peroxide in gram-negative bacteria – bacterial peroxidases

This work was supported by Fundação para a Ciência e Tecnologia (FCT) (project grants to SRP, PTDC/BIA-PRO/109796/2009 and PTDC/BIA-BQM/29442/2017, and a scholarship to CSN, SFRH/BD/87878/2012). Unidade de Ciências Biomoleculares Aplicadas-UCIBIO was financed by national funds from FCT/MEC (UID/Multi/04378/2019).Bacteria display an array of enzymes to detoxify reactive oxygen species that cause damage to DNA and to other biomolecules leading to cell death. Hydrogen peroxide is one of these species, with endogenous and exogenous sources, such as lactic acid bacteria, oxidative burst of the immune system or chemical reactions at oxic-anoxic interfaces. The enzymes that detoxify hydrogen peroxide will be the focus of this review, with special emphasis on bacterial peroxidases that reduce hydrogen peroxide to water. Bacterial peroxidases are periplasmic cytochromes with either two or three c-type haems, which have been classified as classical and non-classical bacterial peroxidases, respectively. Most of the studies have been focus on the classical bacterial peroxidases, showing the presence of a reductive activation in the presence of calcium ions. Mutagenesis studies have clarified the catalytic mechanism of this enzyme and were used to propose an intramolecular electron transfer pathway, with far less being known about the intermolecular electron transfer that occurs between reduced electron donors and the enzyme. The physiological function of these enzymes was not very clear until it was shown, for the non-classical bacterial peroxidase, that this enzyme is required for the bacteria to use hydrogen peroxide as terminal electron acceptor under anoxic conditions. These non-classical bacterial peroxidases are quinol peroxidases that do not require reductive activation but need calcium ions to attain maximum activity and share similar catalytic intermediates with the classical bacterial peroxidases.preprintpublishe

Factors associated with diversity, quantity and zoonotic potential of ectoparasites on urban mice and voles

Wild rodents are important hosts for tick larvae but co-infestations with other mites and insects are largely neglected. Small rodents were trapped at four study sites in Berlin, Germany, to quantify their ectoparasite diversity. Host-specific, spatial and temporal occurrence of ectoparasites was determined to assess their influence on direct and indirect zoonotic risk due to mice and voles in an urban agglomeration. Rodent-associated arthropods were diverse, including 63 species observed on six host species with an overall prevalence of 99%. The tick Ixodes ricinus was the most prevalent species, found on 56% of the rodents. The trapping location clearly affected the presence of different rodent species and, therefore, the occurrence of particular host-specific parasites. In Berlin, fewer temporary and periodic parasite species as well as non-parasitic species (fleas, chiggers and nidicolous Gamasina) were detected than reported from rural areas. In addition, abundance of parasites with low host-specificity (ticks, fleas and chiggers) apparently decreased with increasing landscape fragmentation associated with a gradient of urbanisation. In contrast, stationary ectoparasites, closely adapted to the rodent host, such as the fur mites Myobiidae and Listrophoridae, were most abundant at the two urban sites. A direct zoonotic risk of infection for people may only be posed by Nosopsyllus fasciatus fleas, which were prevalent even in the city centre. More importantly, peridomestic rodents clearly supported the life cycle of ticks in the city as hosts for their subadult stages. In addition to trapping location, season, host species, body condition and host sex, infestation with fleas, gamasid Laelapidae mites and prostigmatic Myobiidae mites were associated with significantly altered abundance of I. ricinus larvae on mice and voles. Whether this is caused by predation, grooming behaviour or interaction with the host immune system is unclear. The present study constitutes a basis to identify interactions and vector function of rodent-associated arthropods and their potential impact on zoonotic diseases

Isolierung und Charakterisierung einer cDNA fuer die cytosolische Acetoacetyl-CoA-Thiolase aus Raphanus sativus L. durch Komplementierung einer Saccharomyces cerevisiae-Mutante

For the first time this study presents the successful cloning and functional characterization of a plant gene coding for cytosolic acetoacyl-CoA thiolase (cAACT). For the cloning of cAACT from radish, yeast mutants (erg10A), deficient in cAACT enzyme activity and therefore auxotrophic for ergosterol, were used to isolate the clones bearing the radish cAACT cDNA by functional complementation. The radish cDNA library was converted into the integrated plasmid vector pYEUra3, which has been transformed into a Saccharomyces cerevisae strain with a mutation in the endogenous cAACT gene (erg10A). Positive radish cAACT clones have been indentified by the restoration of wild-type yeast growth characteristics. Using the cAACT probe under highly stringent conditions, a gel blot analysis of differentially digested genomic DNA gave strong evidence for the radish gene being organized as a single copy gene, which most likely is interrupted by several introns. (WEN)SIGLEAvailable from TIB Hannover: RN 5800(30) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

A key performance indicator system for the systematic evaluation of simulation results as a basis for energy-efficient industrial cluster optimization

Aktuelle Krisen wie weltweit gestörte Lieferketten, steigende Energiepreise und nicht zuletzt der Klimawandel führen einmal mehr vor Augen, wie wichtig der effiziente Umgang mit Ressourcen und insbesondere mit Energie ist. Industrielle Symbiose (IS) verfolgt das Ziel, mithilfe energetisch-stofflicher Austauschbeziehungen innerhalb von Eco-Industrial Parks (EIP) die Ressourceneffizienz zu erhöhen und somit einen wichtigen Beitrag zur Minderung der eingangs genannten Probleme beizusteuern. In der Literatur gibt es eine Vielzahl von Ansätzen, mit denen IS-Maßnahmen untersucht und optimiert werden. Diese unterscheiden sich stark hinsichtlich ihres Betrachtungsumfangs und des Detaillierungsgrades, mit dem die einzelnen Prozesse analysiert und geplant werden. Aufgrund der Komplexität der Zusammenhänge innerhalb eines EIP sind Simulationen hilfreich. Diese sind jedoch meist speziell auf einen konkreten EIP zugeschnitten und lassen sich nicht ohne Weiteres auf andere EIPs anwenden. Im Rahmen aufeinanderfolgender EIP-Projekte an der TU Dresden werden deshalb Simulationsmodelle sowie eine automatisierte Optimierung der Austauschbeziehungen für die Anwendung auf unterschiedliche EIPs entwickelt. Für die Optimierung ist die Bewertung der Simulationsergebnisse unerlässlich. Aus diesem Grund wird in diesem Beitrag eine Methode zu systematischen Bewertung von Simulationsläufen möglicher Konstellationen an Symbiosen vorgestellt. Hierbei werden auch unterschiedliche Betrachtungsschwerpunkte durch eine Gewichtung der Bewertungsparameter berücksichtigt.Current crises such as globally disrupted supply chains, rising energy prices and, of course, climate change demonstrate once again how important it is to use resources, and energy in particular, efficiently. Industrial symbiosis (IS) aims at increasing resource efficiency by means of energy-material exchange relationships within Eco-Industrial Parks (EIP) and thus contributes to the reduction of the problems mentioned above. In the literature, there is a variety of approaches to investigate and optimize IS measures. These differ significantly in terms of their scope of consideration and the level of detail with which the individual processes are analyzed or planned. Due to the complexity of the interrelationships within an EIP, simulations are helpful. However, these are usually designed for a specific EIP and cannot be applied to other EIPs without further effort. In the context of successive EIP projects at the TU Dresden, simulation models and an automated optimization of the exchange relationships are therefore being developed for application to different EIPs. The evaluation of simulation results is essential for optimization. For this reason, this paper presents a method for the systematic evaluation of simulation runs of possible constellations of symbioses. In this context, different focus areas are also taken into consideration by weighting the evaluation parameters

Mitigating the Urban Heat Island Effect in Megacity Tehran

Cities demonstrate higher nocturnal temperatures than surrounding rural areas, which is called “urban heat island” (UHI) effect. Climate change projections also indicate increase in the frequency and intensity of heat waves, which will intensify the UHI effect. As megacity Tehran is affected by severe heatwaves in summer, this study investigates its UHI characteristics and suggests some feasible mitigation strategies in order to reduce the air temperature and save energy. Temperature monitoring in Tehran shows clear evidence of the occurrence of the UHI effect, with a peak in July, where the urban area is circa 6 K warmer than the surrounding areas. The mobile measurements show a park cool island of 6-7 K in 2 central parks, which is also confirmed by satellite images. The effectiveness of three UHI mitigation strategies high albedo material (HAM), greenery on the surface and on the roofs (VEG), and a combination of them (HYBRID) has been studied using simulation with the microscale model ENVI-met. All three strategies show higher cooling effect in the daytime. The average nocturnal cooling effect of VEG and HYBRID (0.92, 1.10 K) is much higher than HAM (0.16 K), although high-density trees show a negative effect on nocturnal cooling