Coarse Grained Molecular Dynamics Simulations of the Fusion of Vesicles Incorporating Water Channels

As the dynamics of the cell membrane and the working mechanisms of proteins cannot be readily asserted at a molecular level, many different hypotheses exist that try to predict and explain these processes, for instance vesicle fusion. Therefore, we use coarse grained molecular dynamics simulations to elucidate the fusion mechanism of vesicles. The implementation of this method with hydrophilic and hydrophobic particles is known for its valid representation of bilayers. With a minimalistic approach, using only 3 atom types, 12 atoms per two-tailed phospholipids and incorporating only a bond potential and Lennard-Jones potential, phospholipid bilayers and vesicles can be simulated exhibiting authentic dynamics. We have simulated the spontaneous full fusion of both tiny (6 nm diameter) and larger (13 nm diameter) vesicles. We showed that, without applying constraints to the vesicles, the initial contact between two fusing vesicles, the stalk, is initiated by a bridging lipid tail that extends from the membrane spontaneously. Subsequently it is observed that the evolution of the stalk can proceed via two pathways, anisotropic and radial expansion, which is in accordance with literature. Contrary to the spherical vesicles of in vitro experiments, the fused vesicles remain tubular since the internal volume of these vesicles is too small compared to their membrane area. While the lipid bilayer has some permeability for water, it is not high enough to allow for the large flux required to equilibrate the vesicle content in the time accessible to our simulations. To increase the membrane permeability, we incorporate proteinaceous water channels, by applying the coarse grained technique to aquaporin. Even though incorporating water channels in the vesicles does significantly increase water permeability, the vesicles do not become spherical. Presumably the lipids have to be redistributed as well

News discourses on distant suffering: A critical discourse analysis of the 2003 SARS outbreak

News carries a unique signifying power, a power to represent events in particular ways (Fairclough, 1995). Applying Critical Discourse Analysis and Chouliaraki's theory on the mediation of suffering (2006), this article explores the news representation of the 2003 global SARS outbreak. Following a case-based methodology, we investigate how two Belgian television stations have covered the international outbreak of SARS. By looking into the mediation of four selected discursive moments, underlying discourses of power, hierarchy and compassion were unraveled. The analysis further identified the key role of proximity in international news reporting and supports the claim that Western news media mainly reproduce a Euro-American centered world order. This article argues that news coverage of international crises such as SARS constructs and maintains the socio-cultural difference between 'us' and 'them' as well as articulating global power hierarchies and a division of the world in zones of poverty and prosperity, danger and safety

Католицька концепція міжрелігійного діалогу: зміна акцентів

In Arabidopsis roots, the transcription factor MYB72 plays a dual role in the onset of rhizobacteria-induced systemic resistance (ISR) and plant survival under conditions of limited iron availability. Previously, it was shown that MYB72 coordinates the expression of a gene module that promotes synthesis and excretion of iron-mobilizing phenolic compounds in the rhizosphere, a process involved in both iron acquisition and ISR signaling. Here, we show that volatile compounds (VOCs) from ISR-inducing Pseudomonas bacteria are important elicitors of MYB72. VOCs-induced MYB72 is co-expressed with the iron uptake-related genes FERRIC REDUCTION OXIDASE 2 (FRO2) and IRON-REGULATED TRANSPORTER 1 (IRT1) in a FER-LIKE IRON DEFICIENCY INDUCED TRANSCRIPTION FACTOR (FIT)-dependent manner, indicating that MYB72 is an intrinsic part of the plants’ iron acquisition response that is typically activated upon iron starvation. However, VOCs-induced MYB72 is activated independently of the iron availability in the root vicinity. Moreover, rhizobacterial VOCs-mediated induction of MYB72 requires photosynthesis-related signals, while iron deficiency in the rhizosphere can activate MYB72 in the absence of shoot-derived signals. Together, these results show that the ISR- and iron acquisition-related transcription factor MYB72 in Arabidopsis roots is activated by rhizobacterial volatiles and photosynthesis-related signals, and can enhance the iron acquisition capacity of roots independently of the iron availability in the rhizosphere. This work highlights the role of MYB72 in plant processes by which root microbiota simultaneously stimulate systemic immunity and activate the iron uptake machinery in their host plants

GW190814 follow-up with the optical telescope MeerLICHT

The Advanced LIGO and Virgo gravitational wave observatories detected a signal on 2019 August 14 during their third observing run, named GW190814. A large number of electromagnetic facilities conducted follow-up campaigns in the search for a possible counterpart to the gravitational wave event, which was made especially promising given the early source classification of a neutron star-black hole merger.We present the results of the GW follow-up campaign taken with the wide-field optical telescope MeerLICHT, located at the South African Astronomical Observatory Sutherland site. We use our results to constrain possible kilonova models. MeerLICHT observed more than 95% of the probability localisation each night for over a week in three optical bands (u,q,i) with our initial observations beginning almost 2 hours after the GW detection. We describe the search for new transients in MeerLICHT data and investigate how our limiting magnitudes can be used to constrain an AT2017gfo-like kilonova. A single new transient was found in our analysis of MeerLICHT data, which we exclude from being the electromagnetic counterpart to GW190814 due to the existence of a spatially unresolved source at the transient's coordinates in archival data. Using our limiting magnitudes, the confidence with which we can exclude the presence of an AT2017gfo-like kilonova at the distance of GW190814 was low ($<10^{-4}$).Comment: 19 pages, 6 figures, accepted by A&

Reclaiming the political : emancipation and critique in security studies

The critical security studies literature has been marked by a shared commitment towards the politicization of security – that is, the analysis of its assumptions, implications and the practices through which it is (re)produced. In recent years, however, politicization has been accompanied by a tendency to conceive security as connected with a logic of exclusion, totalization and even violence. This has resulted in an imbalanced politicization that weakens critique. Seeking to tackle this situation, the present article engages with contributions that have advanced emancipatory versions of security. Starting with, but going beyond, the so-called Aberystwyth School of security studies, the argument reconsiders the meaning of security as emancipation by making the case for a systematic engagement with the notions of reality and power. This revised version of security as emancipation strengthens critique by addressing political dimensions that have been underplayed in the critical security literature

Staging of breast cancer with PET/CT

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