Morphological development and cytochrome c oxidase activity in Streptomyces lividans are dependent on the action of a copper bound Sco protein

Copper has an important role in the life cycle of many streptomycetes, stimulating the developmental switch between vegetative mycelium and aerial hyphae concomitant with the production of antibiotics. In streptomycetes, a gene encoding for a putative Sco-like protein has been identified and is part of an operon that contains two other genes predicted to handle cellular copper. We report on the Sco-like protein from Streptomyces lividans (Sco Sl ) and present a series of experiments that firmly establish a role for Sco Sl as a copper metallochaperone as opposed to a role as a thiol-disulphide reductase that has been assigned to other bacterial Sco proteins. Under low copper concentrations, a Δ sco mutant in S. lividans displays two phenotypes; the development switch between vegetative mycelium and aerial hyphae stalls and cytochrome c oxidase (CcO) activity is significantly decreased. At elevated copper levels, the development and CcO activity in the Δ sco mutant are restored to wild-type levels and are thus independent of Sco Sl . A CcO knockout reveals that morphological development is independent of CcO activity leading us to suggest that Sco Sl has at least two targets in S. lividans . We establish that one Sco Sl target is the dinuclear Cu A domain of CcO and it is the cupric form of Sco Sl that is functionally active. The mechanism of cupric ion capture by Sco Sl has been investigated, and an important role for a conserved His residue is identified. </jats:p

Divisive Normalization and Neuronal Oscillations in a Single Hierarchical Framework of Selective Visual Attention

Divisive normalization models of covert attention commonly use spike rate modulations as indicators of the effect of top-down attention. In addition, an increasing number of studies have shown that top-down attention increases the synchronization of neuronal oscillations as well, particularly in gamma-band frequencies (25–100 Hz). Although modulations of spike rate and synchronous oscillations are not mutually exclusive as mechanisms of attention, there has thus far been little effort to integrate these concepts into a single framework of attention. Here, we aim to provide such a unified framework by expanding the normalization model of attention with a multi-level hierarchical structure and a time dimension; allowing the simulation of a recently reported backward progression of attentional effects along the visual cortical hierarchy. A simple cascade of normalization models simulating different cortical areas is shown to cause signal degradation and a loss of stimulus discriminability over time. To negate this degradation and ensure stable neuronal stimulus representations, we incorporate a kind of oscillatory phase entrainment into our model that has previously been proposed as the “communication-through-coherence” (CTC) hypothesis. Our analysis shows that divisive normalization and oscillation models can complement each other in a unified account of the neural mechanisms of selective visual attention. The resulting hierarchical normalization and oscillation (HNO) model reproduces several additional spatial and temporal aspects of attentional modulation and predicts a latency effect on neuronal responses as a result of cued attention

On the relation between decoherence and spontaneous symmetry breaking

We have recently shown that there is a limit to quantum coherence in many-particle spin qubits due to spontaneous symmetry breaking. These results were derived for the Lieb-Mattis spin model. Here we will show that the underlying mechanism of decoherence in systems with spontaneous symmetry breaking is in fact more general. We present here a generic route to finding the decoherence time associated with spontaneous symmetry breaking in many particle qubits, and subsequently we apply this approach to two model systems, indicating how the continuous symmetries in these models are spontaneously broken and discussing the relation of this symmetry breaking to the thin spectrum. We then present in detail the calculations that lead to the limit to quantum coherence, which is due to energy shifts in the thin spectrum.Comment: 14 pages, 5 figure

Similarity of technical logics of cropping systems organization between conventional and recently converted organic farmers in a water catchment area

Organic farming is considered as a solution to preserve water quality in drinking water catchments. For local managers of these catchments it is thus important to identify conventional farmers for potential conversion to organic farming. The aim of this article is to assess technical similarity of conventional farmers concerned by a water catchment to organic farming. We build a typology of farmers based on technical logics related to cropping systems organization. We differentiated five types of farmers among 18 conventional dairy farmers and three recently converted organic farmers. According to our results, only two farmers can be considered as close to technical logics identified in organic farms. Nevertheless, we could identify partial technical similarities for two other farmer groups. These similarities may be useful for catchment managers to initiate transitions towards organic farming

Innate immune modulation in atherosclerosis and vascular

Atherosclerosis is a chronic inflammatory disease, consisting of the buildup of lipids in the vessel wall. Advanced lesions may become unstable and rupture, leading to major cardiovascular complications such as myocardial infarction or stroke. In this thesis, the role of the innate immune system in atherosclerosis has been investigated. We have shown that inhibition of complement component C5a results in reduced atherosclerotic lesion formation as well as reduced lesion destabilization. Also, we have provided evidence that activation of mast cells surrounding the atherosclerotic lesion results in increased accumulation of the neutrophil, thus aggravating the local inflammatory response. Moreover, we have investigated the effect of microRNA inhibition of atherosclerosis. MicroRNAs are short non-coding RNA strands with the ability to modulate the expression of multiple genes. With a unique Reversed Target Prediction we have identified microRNAs that are predicted to affect multiple atherosclerosis-related genes. We inhibited one of these predicted microRNAs: microRNA-494, and investigated its role in vivo. Interestingly, we observed a striking reduction in atherosclerotic lesion formation, as well as an increase in lesion stability.Nederlandse Hartstichting Greiner Bio-One ChipsoftUBL - phd migration 201

Organic farming to preserve water quality?Comparison of three emblematic cases of successful management of drinking water catchment area

Protecting water resources from pollutants generated by agricultural activities is becoming more strictly regulated in Europe today, with an obligation to achieveresults. This means that towns willing to improve quality of their domestic water supply are required to regulate farmers’ practices in the water catchment areas. In this paper, we studied three cases (Munich and Augsburg in Germany, and Lons-le-Saunier in France) often listed as successful initiatives/ experiences of preservation of water quality by local authorities that have developed coordination with farmers. In this paper, we carried out a comparative analysis of the construction of city-farmer agreements, based on in-depth surveys and with a particular focus on the role of conversion to organic farming in these agreements. We highlighted several significant differences between these three case studies, with regard to the delimitation of the city’s field of action, the nature of compensation proposed to the farmers, the direct involvement of the city council in the acquisition of land in the vulnerable zone, and the importance granted to organic farming. However, in all three cases we also found similarities, such as the importance, for successful city-farmer coordination, of a facilitator as an intermediary between the two parties, as well as dialogue and contracts that span sufficiently long periods. When these conditions are met, which is the case in the two German cities, the results on the water quality are positive. From this point of view, the German water utilities’ status as “private companies owned by the city” seems to be highly conducive to the introduction of truly environment-friendly practices by farmers. In contrast, in the French case, the greater weight of regulatory constraints on the establishment of direct relations with farmers tends to prevent any fluidity in modes of action and to trigger tensions. Finally, the specific study of the role of conversion to organic farming in the solutions proposed and accepted by the farmers highlights a number of factors needed for the territorial development of this typeof farming: a strong political will that translates into high financial incentives, guaranteed local markets for organic products, and necessary technical support. These factors nevertheless remain insufficient in two of the three case studies, and only the city of Munich, starting off with a particularly favourable situation, has been able to achieve a territorial development of organic farming in tandem with the preservation of its water resources