Arundhati Pillai

Abstract Arsenic contamination of water sources is a global problem, affecting numerous (especially developing) countries across the world. Exposure to exorbitantly high concentrations reaching 400 parts per billion of arsenic in water sources lead to numerous health complications, including the development of respiratory, neurological, and cancerous diseases. This study focused on developing an innovative, low-cost, and gravity-driven filtration system using a novel iron oxide nanoparticle-loaded polyurethane (PU) foam by which people in developing countries may have easy access to an effective, affordable, and easily fabricated filtration system. After successfully synthesizing the new iron oxide nanoparticle-loaded PU foam, effectiveness of the foam was tested by developing a filtration system consisting of vertical polyvinyl-chloride tubing inserted with 10 and 20 cm of PU foams. Samples of arsenic-contaminated water with known concentrations of 100 and 200 ppb were run through each of the systems numerous times for one and five run cases. The system with 20 cm of PU foam and five runs successfully filtered out around 50–70% of the arsenic from the 100 and 200 ppm samples. The filtration process was quite fast (and hence practical) with each run completing in 5–10 minutes' time. Future research is expected to improve this promising start.

Axo–glial junctions (AGJs) play a critical role in the organization and maintenance of molecular domains in myelinated axons. Neurexin IV/Caspr1/paranodin (NCP1) is an important player in the formation of AGJs because it recruits a paranodal complex implicated in the tethering of glial proteins to the axonal membrane and cytoskeleton. Mice deficient in either the axonal protein NCP1 or the glial ceramide galactosyltransferase (CGT) display disruptions in AGJs and severe ataxia. In this article, we correlate these two phenotypes and show that both NCP1 and CGT mutants develop large swellings accompanied by cytoskeletal disorganization and degeneration in the axons of cerebellar Purkinje neurons. We also show that αII spectrin is part of the paranodal complex and that, although not properly targeted, this complex is still formed in CGT mutants. Together, these findings establish a physiologically relevant link between AGJs and axonal cytoskeleton and raise the possibility that some neurodegenerative disorders arise from disruption of the AGJs.

The formation of paranodal axo-glial junctions is critical for the rapid and efficient propagation of nerve impulses. Genetic ablation of genes encoding the critical paranodal proteins Caspr, contactin (Cont), and the myelinating glia-specific isoform of Neurofascin (NfascNF155) results in the disruption of the paranodal axo-glial junctions, loss of ion channel segregation, and impaired nerve conduction, but the mechanisms regulating their interactions remains elusive. Here, we report that loss of immunoglobulin (Ig) domains 5 and 6 in NfascNF155 in mice phenocopies complete ablation of NfascNF155. The mutant mice lack paranodal septate junctions, resulting in the diffusion of Caspr and Cont from the paranodes, and redistribution of the juxtaparanodal potassium channels towards the nodes. While critical for NfascNF155 function, we find that Ig5-6 are dispensable for nodal NfascNF186 function. Moreover, in vitro binding assays using Ig5-6 deletion constructs reveal their importance for the association of NfascNF155 with Cont. These findings provide the first molecular evidence demonstrating domain specific requirements controlling the association of the paranodal tripartite complex in vivo. Our studies further emphasize that in vivo structure/function analysis is necessary to define the unique protein/protein interactions that differentially regulate the functions of Neurofascins during axonal domain organization.