Synthese und Charakterisierung von Rezeptoren für eine lichtgetriebene Oxoanionenkondensation

Die lichtgetriebene Oxoanionenkondensation soll nach dem Vorbild der ATP-Synthase die Umwandlung von Lichtenergie in chemische Energie ermöglichen. In Vorarbeiten wurde ein photoschaltbarer Rezeptor entwickelt, welcher die Kondensation von Monovanadat zu Tetravanadat induzieren kann. Dieser besteht neben einer Azobenzoleinheit aus Zink-Cycleneinheiten als Bindungsstellen für Oxoanionen. Ziel dieser Arbeit war die Synthese und Charakterisierung neuer Rezeptoren für eine artifizielle Vanadatkondensation. Als Grundlage dient der postulierte Tetravanadatkomplex des Zink-Cyclen-basierten Rezeptors. Eine kovalente Verknüpfung der Koordinations-stellen soll zu einer Vororientierung führen und gleichzeitig die Flexibilität des Systems reduzieren. Dadurch kann das Koordinations-verhalten des Rezeptors vereinfacht und eine Polymerbildung unterdrückt werden. Quanten-mechanische Berechnungen ergaben, dass die Verwendung von Diethylether-Brücken eine günstige Komplexierungsgeometrie zulässt. Im Rahmen dieser Arbeit wurde eine Vielzahl an photoschaltbaren Rezeptoren dargestellt und auf ihre Fähigkeit hin untersucht, die Kondensation von Vanadaten zu katalysieren. Der Schwerpunkt der Synthese bestand in der Entwicklung einer gezielten Schutzgruppen-strategie, um die gewünschte Funktionalisierung der Cycleneinheiten zu realisieren. Entsprechend umfasste die Darstellung des Diethylether-verbrückten Makrozyklus insgesamt 13 Reaktionsschritte. Durch Austausch der Gegenionen konnten außerdem die Lösungs-eigenschaften der Rezeptoren variiert werden. 51V-NMR-spektroskopische Messungen zeigten einen starken Einfluss der untersuchten Moleküle auf das Vanadatgleichgewicht. Sowohl in Wasser als auch in einem organischen Lösungsmittel erwies sich das Koordinations-verhalten als wider Erwarten komplex. Eine selektive Anreicherung des Tetravanadats oder anderer Oligovanadaten konnte nicht festgestellt werden.Artificial light-driven oxoanion condensation should allow the conversion of light energy into chemical energy similar to biological ATP synthase. In previous works, a photoswitchable receptor was developed, which induces the condensation of monovanadate to tetravanadate. This receptor contains zinc cyclen units as binding sites for oxoanions and an azobenzene unit for affinity switching. The aim of this work was the synthesis and characterization of new re-ceptors for an artificial vanadate condensation. The target tetravanadate complex of the zinc cyclen based receptor serves as a basis. Covalent linkage of the coordination sites was designed to achieve pre-orientation and rigidity to optimize the coordination strength of the receptor and to suppress polymer formation. Quantum mechanical calculations showed that the use of diethyl ether bridges allows for a favorable complexation geometry. In this work, a variety of photoswitchable receptors are presented and investigated regarding their ability to catalyze vanadate condensation. The synthetic focus was on developing a targeted protecting group strategy to realize the desired functionalization of the cyclen units. Accordingly, synthesis of the diethyl ether bridged macrocycle included a total of 13 reaction steps. Additionally, the solution properties of the receptors were improved by exchanging the counterions. 51V NMR spectroscopic measurements confirmed a strong influence of the studied molecules on the vanadate equilibrium. Both in water and in an organic sol-vent, the coordination behavior proved to be unexpectedly complex. Selective enrichment of tetravanadate or other oligovanadates could not be detected

Spatio-spectral characteristics of parametric down-conversion in waveguide arrays

High dimensional quantum states are of fundamental interest for quantum information processing. They give access to large Hilbert spaces and, in turn, enable the encoding of quantum information on multiple modes. One method to create such quantum states is parametric down-conversion (PDC) in waveguide arrays (WGAs) which allows for the creation of highly entangled photon-pairs in controlled, easily accessible spatial modes, with unique spectral properties. In this paper we examine both theoretically and experimentally the PDC process in a lithium niobate WGA. We measure the spatial and spectral properties of the emitted photon-pairs, revealing strong correlations between spectral and spatial degrees of freedom of the created photons. Our measurements show that, in contrast to prior theoretical approaches, spectrally dependent coupling effects have to be taken into account in the theory of PDC in WGAs. To interpret the results, we developed a theoretical model specifically taking into account spectrally dependent coupling effects, which further enables us to explore the capabilities and limitations for engineering the spatial correlations of the generated quantum states.Comment: 26 pages, 11 figure

How artificial potential field algorithms can help to simulate trade-offs in movement behaviour of reef fishes

IntroductionSpace use patterns in fish result from the interactions between individual movement behaviour and characteristics of the environment. Herbivorous parrotfishes, for instance, are constrained by the availability of resources and different predation risks. The resulting spatial distribution of the fish population can strongly influence community composition and ecosystem resilience.MethodsIn a novel approach, we combine individual-based modelling (IBM) with an artificial potential field algorithm to realistically represent fish movements and the decision-making process. Potential field algorithms, which are popular methods in mobile robot path planning, efficiently generate the best paths for an entity to navigate through vector fields of repellent and attracting forces. In our model the repellent and attracting forces are predation risk and food availability, both implemented as separate grid-based vector fields. The coupling of individual fish bioenergetics with a navigation capacity provides a mechanistic basis to analyse how the habitat structure influences population dynamics and space utilization.ResultsModel results indicate that movement patterns and the resulting spatial distributions strongly depend on habitat fragmentation with the bioenergetic capacity to spawn and reproduce being particularly susceptible processes at the individual level. The resulting spatial distributions of the population are more irregularly distributed among coral reef patches the more the coral reef habitat becomes fragmented and reduced.DiscussionThis heterogeneity can have strong implications for the delivered ecosystem functioning, e.g., by concentrating or diluting the grazing effort. Our results also highlight the importance of incorporating individual foraging-path patterns and the spatial exploitation of microhabitats into marine spatial planning by considering the effects of fragmentation. The integration of potential fields into IBMs represents a promising strategy to advance our understanding of complex decision-making in animals by implementing a more realistic and dynamic decision-making process, in which each fish weighs different rewards and risks of the environment. This information may help to identify core areas and essential habitat patches and assist in effective marine spatial management

The HOX Code as a “biological fingerprint” to distinguish functionally distinct stem cell populations derived from cord blood

AbstractMesenchymal stem cells (MSC) have been isolated from almost every adult tissue. In cord blood (CB), different non-hematopoietic CD45-, CD34− adherent cell populations can be generated: the cord blood derived MSC (CB-MSC), that behave almost like MSC from bone marrow (BM-MSC), and unrestricted somatic stem cells (USSC) which show a distinct differentiation potential into all three germ layers. However, distinguishing these populations easily by molecular markers is still a concern. In this study we were able to present the HOX expression pattern of USSC, CB-MSC and BM-MSC, which in fact allows a discrimination of these populations.Briefly, RT-PCR analysis of the HOX code revealed a high similarity between BM-MSC and CB-MSC, which are both HOX-positive, whereas USSC resembled H9 embryonic stem cells HOX-negative.Especially HOXA9, HOXB7, HOXC10 and HOXD8 are good candidate markers to discriminate MSC from USSC. Thus, our data suggest that the "biological fingerprint" based on the HOX code can be used to distinguish functionally distinct MSC populations derived from bone marrow and cord blood

Characterisation of the Cyanate Inhibited State of Cytochrome c Oxidase

Heme-copper oxygen reductases are terminal respiratory enzymes, catalyzing the reduction of dioxygen to water and the translocation of protons across the membrane. Oxygen consumption is inhibited by various substances. Here we tested the relatively unknown inhibition of cytochrome c oxidase (CcO) with isocyanate. In contrast to other more common inhibitors like cyanide, inhibition with cyanate was accompanied with the rise of a metal to ligand charge transfer (MLCT) band around 638nm. Increasing the cyanate concentration furthermore caused selective reduction of heme a. The presence of the CT band allowed for the first time to directly monitor the nature of the ligand via surface-enhanced resonance Raman (SERR) spectroscopy. Analysis of isotope sensitive SERR spectra in comparison with Density Functional Theory (DFT) calculations identified not only the cyanate monomer as an inhibiting ligand but suggested also presence of an uretdion ligand formed upon dimerization of two cyanate ions. It is therefore proposed that under high cyanate concentrations the catalytic site of CcO promotes cyanate dimerization. The two excess electrons that are supplied from the uretdion ligand lead to the observed physiologically inverse electron transfer from heme a(3) to heme a

Abschlussbericht zur Evaluation des Landestransparenzgesetzes Rheinland-Pfalz (LTranspG)

Das Deutsche Forschungsinstitut für öffentliche Verwaltung (FÖV) wurde vom Ministerium des Innern und für Sport Rheinland-Pfalz mit der Evaluierung des Landestransparenzgesetz Rheinland-Pfalz (LTranspG) beauftragt. Als zweites deutsches Bundesland und als erstes Flächenland hat Rheinland-Pfalz ein Transparenzgesetz eingeführt. Zu den Zielen des Geset-zes gehört es, die Transparenz der Verwaltung und die Kontrolle staatlichen Handelns durch Bürgerinnen und Bürger zu fördern sowie Transparenz als Leitlinie in der Verwaltung zu ver-ankern. Das Gesetz ergänzt den Anspruch auf Zugang zu Informationen der Verwaltung auf Antrag um eine proaktive Veröffentlichungspflicht für bestimmte Informationen auf der Transparenz-Plattform des Landes (https://tpp.rlp.de/). Außerdem wurde für einige transpa-renzpflichtige Stellen, die zur Auskunft auf Antrag verpflichtet sind, die Möglichkeit geschaf-fen, freiwillig Informationen auf der Transparenz-Plattform zu veröffentlichen. Das Gesetz sieht eine Evaluation vor; der vorliegende Bericht stellt die Ergebnisse dieser Evaluation dar. Das FÖV untersuchte im Rahmen der Evaluation die Erreichung der Gesetzesziele, die Auswir-kungen des Gesetzesvollzugs auf die Verwaltung und die Nutzung der Informationsangebote und -antragsmöglichkeiten durch die Bürgerinnen und Bürger. Im Ergebnis zeigte sich, dass das Hauptziel der Vereinfachung und Erweiterung des Informationszugangs erreicht wird; die Nachfrage nach Informationen per Antrag oder durch die Nutzung der Transparenz-Platt-form erscheint noch steigerungsfähig

Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability

Kampf J, Gerwig J, Kruse K, et al. Selective Pressure for Biofilm Formation in Bacillus subtilis: Differential Effect of Mutations in the Master Regulator SinR on Bistability. mBio. 2018;9(5): e01464-18

Proteome-wide analysis reveals an age-associated cellular phenotype of in situ aged human fibroblasts

We analyzed an ex vivo model of in situ aged human dermal fibroblasts, obtained from 15 adult healthy donors from three different age groups using an unbiased quantitative proteome-wide approach applying label-free mass spectrometry. Thereby, we identified 2409 proteins, including 43 proteins with an age-associated abundance change. Most of the differentially abundant proteins have not been described in the context of fibroblasts' aging before, but the deduced biological processes confirmed known hallmarks of aging and led to a consistent picture of eight biological categories involved in fibroblast aging, namely proteostasis, cell cycle and proliferation, development and differentiation, cell death, cell organization and cytoskeleton, response to stress, cell communication and signal transduction, as well as RNA metabolism and translation. The exhaustive analysis of protein and mRNA data revealed that 77 % of the age-associated proteins were not linked to expression changes of the corresponding transcripts. This is in line with an associated miRNA study and led us to the conclusion that most of the age-associated alterations detected at the proteome level are likely caused post-transcriptionally rather than by differential gene expression. In summary, our findings led to the characterization of novel proteins potentially associated with fibroblast aging and revealed that primary cultures of in situ aged fibroblasts are characterized by moderate age-related proteomic changes comprising the multifactorial process of aging

Extremely robust photocurrent generation of titanium dioxide photoanodes bio-sensitized with recombinant microalgal light-harvesting proteins.

Lämmermann N, Schmid-Michels F, Weissmann A, Wobbe L, Hütten A, Kruse O. Extremely robust photocurrent generation of titanium dioxide photoanodes bio-sensitized with recombinant microalgal light-harvesting proteins. Scientific reports. 2019;9(1): 2109.Bio-dyes for light harvesting in dye-sensitized solar cells (DSSC) have the advantage of being environmentally-friendly, non-toxic alternatives, which can be produced in a sustainable fashion. Free photosynthetic pigments are unstable in the presence of light and oxygen, a situation which can hardly be avoided during the operation of DSSCs, especially in large-scale applications. We therefore investigated the recombinant light-harvesting protein LHCBM6, which naturally occurs in the photosynthetic apparatus of the green microalga Chlamydomonas reinhardtii as a bio-dye in DSSCs. Photocurrent densities of up to 0.87 and 0.94 mA·cm-2 were determined for the DSSCs and solar energy to electricity conversion efficiencies (η) reached about 0.3% (100 mW·cm-2; AM 1.5 G filter applied). Importantly, we observed an unprecedented stability of LHCII-based DSSCs within long DSSC operation times of at least 7 days in continuous light and show that operation times are restricted by electrolyte decomposition rather than reduced dye performance, as could be demonstrated by DSSC reactivation following re-supplementation with fresh electrolyte. To the best of our knowledge, this is the first study analysing bio-dye sensitized DSSCs over such long periods, which revealed that during illumination an activation of the DSSCs occurs