Heavy Water Reduces GFP Expression in Prokaryotic Cell-Free Assays at the Translation Level While Stimulating Its Transcription

The in vitro proliferation of prokaryotic and eukaryotic cells is remarkably hampered in the presence of heavy water (D2O). Impairment of gene expression at the transcription or translation level can be the base for this effect. However, insights into the underlying mechanisms are lacking. Here, we employ a cell-free expression system for the quantitative analysis of the effect of increasing percentages of D2O on the kinetics of in-vitro GFP expression. Experiments are designed to discriminate the rates of transcription, translation, and protein folding using pDNA and mRNA vectors, respectively. We find that D2O significantly stimulates GFP expression at the transcription level but acts as a suppressor at translation and maturation (folding) in a linear dose-dependent manner. At a D2O concentration of 60%, the GFP expression rate was reduced to 40% of an undisturbed sample. We observed a similar inhibition of GFP expression by D2O in a recombinant Escherichia coli strain, although the inhibitory effect is less pronounced. These results demonstrate the suitability of cell-free systems for quantifying the impact of heavy water on gene expression and establish a platform to further assess the potential therapeutic use of heavy water as antiproliferative agent

Fullerene-based Biocomponents : New Concepts For Functionalising Membranes

Lipophilic hexakisadducts of fullerene C60 form unprecedented rod-like nanoaggregates in phospholipid-membrane bilayers, resulting in modification of the micromechanic properties and stabilisation of the membrane. Lipofullerenes with amphiphilic side chains enable additionally derivatisation and molecular recognition at the membrane surface. The amphiphilic spacer acts as a transmembrane anchor and provides the terminal functionality outside of the membrane. New systems derived from parent compound 3 carry two functional groups each and can be easily modified due to the modular synthesis. Terminal functionalities to be investigated include D(+)-biotin and IDA (iminodiacetic acid) ligands, as used in nickel-histidine tags. Modification of the lipophilic region, for instance with unsaturated addends is also possible. These addends should allow polymerisation inside the membrane and potentially lead to a tremendous increase of the membrane rigidity. Furthermore, mono- and bilayer-forming fullerene derivatives without the membrane-forming support of lecithins are investigated and exhibit interesting features

Instagrammatics and digital methods: Studying visual social media, from selfies and GIFs to memes and emoji

Visual content is a critical component of everyday social media, on platforms explicitly framed around the visual (Instagram and Vine), on those offering a mix of text and images in myriad forms (Facebook, Twitter, and Tumblr), and in apps and profiles where visual presentation and provision of information are important considerations. However, despite being so prominent in forms such as selfies, looping media, infographics, memes, online videos, and more, sociocultural research into the visual as a central component of online communication has lagged behind the analysis of popular, predominantly text-driven social media. This paper underlines the increasing importance of visual elements to digital, social, and mobile media within everyday life, addressing the significant research gap in methods for tracking, analysing, and understanding visual social media as both image-based and intertextual content.In this paper, we build on our previous methodological considerations of Instagram in isolation to examine further questions, challenges, and benefits of studying visual social media more broadly, including methodological and ethical considerations. Our discussion is intended as a rallying cry and provocation for further research into visual (and textual and mixed) social media content, practices, and cultures, mindful of both the specificities of each form, but also, and importantly, the ongoing dialogues and interrelations between them as communication forms

Changes of the physical properties of the liquid-ordered phase with temperature in binary mixtures of DPPC with cholesterol: A (2)H-NMR, FT-IR, DSC, and neutron scattering study

The structure of the so-called liquid-ordered (lo) phase of binary mixtures of DPPC-d(62) with cholesterol was studied between 20-50 mol% cholesterol using (2)H-NMR, FT-IR, DSC, and neutron specular reflection. Different model systems such as multilamellar vesicles, spherical supported vesicles, and oriented multilayers were used. We observed significant changes of the lo phase structure in the physiological relevant temperature region between 30-45°C. (2)H-NMR in combination with lineshape simulations provides evidence for a drastic effect of cholesterol on the shape of multilamellar vesicles due to magnetic field orientation. Moreover, the data indicates a significant change of the extent of this partial orientation for DPPC-d(62) multilamellar vesicles containing 25 mol% cholesterol between 36-42°C. The semiaxes ratio of the (due to magnetic field orientation) ellipsoidal multilamellar vesicles changes over this temperature range by ≈25%. (2)H-NMR and FT-IR measurements indicate changes of the average orientational order at the bilayer center in the same temperature range and a significant increase of the number of end-gauche conformers while the majority of the methylene groups remain in an all-trans conformation. Additionally, specular reflection of neutrons shows a concomitant reduction of the bilayer thickness by 4 Å. Based on a model of the arrangement of DPPC and cholesterol in the lo phase, a molecular mechanism is proposed in which increasing the temperature between 30 and 45°C has the effect of driving cholesterol from the bilayer center towards the head group region

Heavy Water Reduces GFP Expression in Prokaryotic Cell-Free Assays at the Translation Level While Stimulating Its Transcription

The in vitro proliferation of prokaryotic and eukaryotic cells is remarkably hampered in the presence of heavy water (D2O). Impairment of gene expression at the transcription or translation level can be the base for this effect. However, insights into the underlying mechanisms are lacking. Here, we employ a cell-free expression system for the quantitative analysis of the effect of increasing percentages of D2O on the kinetics of in-vitro GFP expression. Experiments are designed to discriminate the rates of transcription, translation, and protein folding using pDNA and mRNA vectors, respectively. We find that D2O significantly stimulates GFP expression at the transcription level but acts as a suppressor at translation and maturation (folding) in a linear dose-dependent manner. At a D2O concentration of 60%, the GFP expression rate was reduced to 40% of an undisturbed sample. We observed a similar inhibition of GFP expression by D2O in a recombinant Escherichia coli strain, although the inhibitory effect is less pronounced. These results demonstrate the suitability of cell-free systems for quantifying the impact of heavy water on gene expression and establish a platform to further assess the potential therapeutic use of heavy water as antiproliferative agent