Plakophilin 3 and Par3 Facilitate Desmosomes’ association with the Apical Junctional Complex

Desmosomes (DSMs) together with Adherens Junctions (AJs) and Tight Junctions (TJs) constitute the apical cell junctional complex (AJC). While the importance of the apical and basolateral polarity machinery in the organization of AJs and TJs is well-established, how DSMs are positioned within the AJC is not understood. Here we use highly polarized DLD1 cells as a model to address how DSMs integrate into the AJC. We found that knockout of the desmosomal ARM protein Pkp3, but not other major DSM proteins, uncouples DSMs from AJC without blocking DSM assembly. DLD1 cells also exhibit a prominent extra-DSM pool of Pkp3, concentrated in tricellular (tC) contacts. Probing distinct apicobasal polarity pathways revealed that neither the DSM's association with AJC, nor the extra-DSM pool of Pkp3 are abolished in cells with defects in Scrib module proteins responsible for basolateral membrane development. However, a loss of the apical polarity protein, Par3 completely eliminates the extra-DSM pool of Pkp3 and disrupts AJC localization of desmosomes, dispersing these junctions along the entire length of cell-cell contacts. Our data are consistent with a model whereby Par3 facilitates DSM assembly within the AJC, controlling the availability of an assembly competent pool of Pkp3 stored in tC contacts.

Key elements and materials in microbial desalination cells

This chapter presents the most relevant advances achieved during the MIDES project in relation to material development of key elements for microbial desalination cells. The first section is devoted to electrodes. Providing a general overview of the requirements of carbon-based materials to serve either as anodes or cathodes for microbial desalination cells. Advances achieved during MIDES in the development of materials for anode and cathode application are listed. The second section is focussed on ion-exchange membranes for microbial desalination cells. General considerations for the use of these membranes are reported as well as key parameters. Finally, advances in ion-exchange membrane development, in terms of antifouling and their performance in desalination trials, achieved during the MIDES project, are reported.

Polymers and Solvents Used in Membrane Fabrication: A Review Focusing on Sustainable Membrane Development

(1) Different methods have been applied to fabricate polymeric membranes with non-solvent induced phase separation (NIPS) being one of the mostly widely used. In NIPS, a solvent or solvent blend is required to dissolve a polymer or polymer blend. N-methyl-2-pyrrolidone (NMP), dimethylacetamide (DMAc), dimethylformamide (DMF) and other petroleum-derived solvents are commonly used to dissolve some petroleum-based polymers. However, these components may have negative impacts on the environment and human health. Therefore, using greener and less toxic components is of great interest for increasing membrane fabrication sustainability. The chemical structure of membranes is not affected by the use of different solvents, polymers, or by the differences in fabrication scale. On the other hand, membrane pore structures and surface roughness can change due to differences in diffusion rates associated with different solvents/co-solvents diffusing into the non-solvent and with differences in evaporation time. (2) Therefore, in this review, solvents and polymers involved in the manufacturing process of membranes are proposed to be replaced by greener/less toxic alternatives. The methods and feasibility of scaling up green polymeric membrane manufacturing are also examined.