Civic action on social media: fostering digital media literacy and epistemic cognition in the classroom

Social media has become a dominant force in civic life amid widespread concerns about its role in political polarisation and in the spread of misinformation. To prepare citizens to take on these challenges, we need civic education that teaches youth to be capable and responsible consumers, conveyors and producers of online information. To do so, teachers must position students as epistemic agents, fostering the skills they need to engage with online information. In this article, we present the first iteration of a design-based research project on social media and civic action. The project prepares high school students in rural, urban and suburban settings located in Northern California (USA) to engage with issues that resonate with them, to critically examine information about these issues from online sources and to use social media as a vehicle to connect with, inform and mobilise the public. We present the basic design principles that teachers have used to support apt epistemic performance, focusing on the epistemic aims (creating knowledge products that inspire civic action), ideals (taking personal responsibility for the accuracy of information when posting) and reliable processes (sourcing, fact checking and correctly representing information) embedded in their units of instruction. Drawing on teacher interviews and curriculum, we explore the affordances of the curriculum to promote civic action by leveraging student engagement in social media, while also challenging them to critically examine how knowledge is produced and disseminated on social media. We conclude with a discussion of how this work intersects with the aims and methods of social pedagogy

Permeation of the three aromatic dipeptides through lipid bilayers: Experimental and computational study

Publisher's note added August 2016: "This article was originally published online on 27 June 2016 with a sentence missing in the Acknowledgments. After the funding acknowledgments, it should read, “G.S.J. would like to thank Wilson R. Veras Tavarez and Elizabeth De Leon Olmeda of UCC for helpful comments.” AIP Publishing apologizes for this error. All online versions of the article were corrected on 28 June 2016; the article is correct as it appears in the printed version of the journal."The time-resolved parallel artificial membrane permeability assay with fluorescence detection and comprehensive computer simulations are used to study the passive permeation of three aromatic dipeptides—N-acetyl-phenylalanineamide (NAFA), N-acetyltyrosineamide (NAYA), and N-acetyltryptophanamide (NATA) through a 1,2-dioleoyl-sn-glycero-3-phospocholine (DOPC) lipid bilayer. Measured permeation times and permeability coefficients show fastest translocation for NAFA, slowest for NAYA, and intermediate for NATA under physiological temperature and pH. Computationally, we perform umbrella sampling simulations to model the structure, dynamics, and interactions of the peptides as a function of z, the distance from lipid bilayer. The calculated profiles of the potential of mean force show two strong effects—preferential binding of each of the three peptides to the lipid interface and large free energy barriers in the membrane center. We use several approaches to calculate the position-dependent translational diffusion coefficients D(z), including one based on numerical solution the Smoluchowski equation. Surprisingly, computed D(z) values change very little with reaction coordinate and are also quite similar for the three peptides studied. In contrast, calculated values of sidechain rotational correlation times τrot(z) show extremely large changes with peptide membrane insertion—values become 100 times larger in the headgroup region and 10 times larger at interface and in membrane center, relative to solution. The peptides’ conformational freedom becomes systematically more restricted as they enter the membrane, sampling α and β and C7eq basins in solution, α and C7eq at the interface, and C7eq only in the center. Residual waters of solvation remain around the peptides even in the membrane center. Overall, our study provides an improved microscopic understanding of passive peptide permeation through membranes, especially on the sensitivity of rotational diffusion to position relative to the bilayer. Published by AIP Publishing. [http://dx.doi.org/10.1063/1.4954241

Characterization of multiple stable conformers of the EC5 domain of E-cadherin and the interaction of EC5 with E-cadherin peptides

The objectives of this work were to express the EC5 domain of E-cadherin and determine its structural characteristics as well as to evaluate the binding properties of HAV and BLG4 peptides to EC5 using spectroscopic methods. Homophilic interactions of E-cadherins are responsible for cell-cell adhesion in the adherens junctions of the biological barriers (i.e., intestinal mucosa and blood-brain barriers). The EC5 domain of E-cadherin has an important role in T-cell adhesion to intestinal mucosa via αEβ7 integrin-E-cadherin interactions. In this study, the expressed EC5 has a high thermal stability (Tm = 64.3 °C); it also has two stable conformations at room temperature, which convert to one conformation at approximately 54.5 °C. NMR and FTIR showed that HAV and BLG4 peptides bind to EC5. HSQC-NMR showed that either Asn or Gln of EC5 was involved in the interactions with HAV and BLG4 peptides. EC5 underwent a conformational change upon interaction with the HAV and BLG4 peptides. Finally, the binding properties of both peptides were modeled by docking experiments, and the results suggest that Asn-46 and Asn-75 of EC5 could be involved during the interaction with the peptides and that the Ser and Trp residues of the HAV and BLG4 peptides, respectively, were important for binding to EC5

An Improved Methodology for Multidimensional High- Throughput Preformulation Characterization of Protein Conformational Stability

The Empirical Phase Diagram (EPD) technique is a vector-based multidimensional analysis method for summarizing large data sets from a variety of biophysical techniques. It can be used to provide comprehensive preformulation characterization of a macromolecule’s higher-order structural integrity and conformational stability. In its most common mode, it represents a type of stimulus-response diagram using environmental variables such as temperature, pH, and ionic strength as the stimulus, with alterations in macromolecular structure being the response. Until now EPD analysis has not been available in a high throughput mode because of the large number of experimental techniques and environmental stressor/stabilizer variables typically employed. A new instrument has been developed that combines circular dichroism, UV-absorbance, fluorescence spectroscopy and light scattering in a single unit with a 6-position temperature controlled cuvette turret. Using this multifunctional instrument and a new software system we have generated EPDs for four model proteins. Results confirm the reproducibility of the apparent phase boundaries and protein behavior within the boundaries. This new approach permits two EPDs to be generated per day using only 0.5 mg of protein per EPD. Thus, the new methodology generates reproducible EPDs in high-throughput mode, and represents the next step in making such determinations more routine

The role of covalent dimerization on the physical and chemical stability of the EC1 domain of human E-cadherin

The objective of this work was to evaluate the solution stability of the EC1 domain of E-cadherin under various conditions. The EC1 domain was incubated at various temperatures (4, 37, and 70 °C) and pH values (3.0, 7.0, and 9.0). At pH 9.0 and 37 or 70 °C, a significant loss of EC1 was observed due to precipitation and a hydrolysis reaction. The degradation was suppressed upon addition of DTT, suggesting that the formation of EC1 dimer facilitated the EC1 degradation. At 4 °C and various pH values, the EC1 secondary and tertiary showed changes upon incubation up to 28 days, and DTT prevented any structural changes upon 28 days of incubation. Molecular dynamics simulations indicated that the dimer of EC1 has higher mobility than does the monomer; this higher mobility of the EC1 dimer may contribute to instability of the EC1 domain

Biophysical and Stabilization Studies of the Chlamydia trachomatis Mouse Pneumonitis Major Outer Membrane Protein

Native Chlamydia trachomatis mouse pneumonitis major outer membrane protein (nMOMP) induces effective protection against genital infection in a mouse challenge model. The conformation of nMOMP is crucial to confer this protective immunity. To achieve a better understanding of the conformational behavior and stability of nMOMP, a number of spectroscopic techniques are employed to characterize the secondary structure (circular dichroism), tertiary structure (intrinsic fluorescence) and aggregation properties (static light scattering and optical density) as a function of pH (3-8) and temperature (10-87.5°C). The data are summarized in an empirical phase diagram (EPD) which demonstrates that the thermal stability of nMOMP is strongly pH-dependent. Three distinctive regions are seen in the EPD. Below the major thermal transition regions, nMOMP remains in its native conformation over the pH range of 3-8. Above the thermal transitions, nMOMP appears in two different structurally altered states; one at pH 3-5 and the other at pH 6-8. The EPD shows that the highest thermal transition point (~ 65°C) of nMOMP is near pH 6. Several potential excipients such as arginine, sodium citrate, Brij 35, sucrose and guanidine are also selected to evaluate their effects on the stability of nMOMP. These particular compounds increase the aggregation onset temperature of nMOMP by more than 10°C, without affecting its secondary and tertiary structure. These results should help formulate a vaccine using a recombinant MOMP