Altered synaptobrevin-II trafficking in neurons expressing a synaptophysin mutation associated with a severe neurodevelopmental disorder

textabstractFollowing exocytosis, synaptic vesicles (SVs) have to be reformed with the correct complement of proteins in the correct stoichiometry to ensure continued neurotransmission. Synaptophysin is a highly abundant, integral SV protein necessary for the efficient retrieval of the SV SNARE protein, synaptobrevin II (sybII). However the molecular mechanism underpinning synaptophysin-dependent sybII retrieval is still unclear. We recently identified a male patient with severe intellectual disability, hypotonia, epilepsy and callosal agenesis who has a point mutation in the juxtamembrane region of the fourth transmembrane domain of synaptophysin (T198I). This mutation had no effect on the activity-dependent retrieval of synaptophysin that was tagged with the genetically-encoded pH-sensitive reporter (pHluorin) in synaptophysin knockout hippocampal cultures. This suggested the mutant has no global effect on SV endocytosis, which was confirmed when retrieval of a different SV cargo (the glutamate transporter vGLUT1) was examined. However neurons expressing this T198I mutant did display impaired activity-dependent sybII retrieval, similar to that observed in synaptophysin knockout neurons. Interestingly this impairment did not result in an increased stranding of sybII at the plasma membrane. Screening of known human synaptophysin mutations revealed a similar presynaptic phenotype between T198I and a mutation found in X-linked intellectual disability. Thus this novel human synaptophysin mutation has revealed that aberrant retrieval and increased plasma membrane localisation of SV cargo can be decoupled in human disease

Wettability Switching Techniques on Superhydrophobic Surfaces

The wetting properties of superhydrophobic surfaces have generated worldwide research interest. A water drop on these surfaces forms a nearly perfect spherical pearl. Superhydrophobic materials hold considerable promise for potential applications ranging from self cleaning surfaces, completely water impermeable textiles to low cost energy displacement of liquids in lab-on-chip devices. However, the dynamic modification of the liquid droplets behavior and in particular of their wetting properties on these surfaces is still a challenging issue. In this review, after a brief overview on superhydrophobic states definition, the techniques leading to the modification of wettability behavior on superhydrophobic surfaces under specific conditions: optical, magnetic, mechanical, chemical, thermal are discussed. Finally, a focus on electrowetting is made from historical phenomenon pointed out some decades ago on classical planar hydrophobic surfaces to recent breakthrough obtained on superhydrophobic surfaces

Fast analysis of power distribution networks using waveform relaxation

This paper presents a fast algorithm for transient simulation of power grids in VLSI systems using waveform relaxation techniques. Novel partitioning methods and convergence accelerators are developed for fast convergence of waveform relaxation iterations when applied to power grid networks. Unlike the direct-solvers, the new method is highly parallelizable and yields significant speed-ups. Numerical examples are presented to demonstrate the validity and efficiency of the proposed method

Transient analysis of power grid networks via waveform relaxation techniques

This paper presents a fast algorithm for transient simulation of power grids in VLSI systems using waveform relaxation techniques. Novel partitioning methods and convergence accelerators are developed for fast convergence of waveform relaxation iterations when applied to power grid networks. Unlike the direct solvers, the new method is highly parallelizable and yields significant speedups. Numerical examples are presented to demonstrate the validity and efficiency of the proposed method

A parallel framework for transient power integrity analysis

This paper presents an efficient parallel algorithm for transient simulation of power grids in VLSI systems. Novel parallel Gauss-Seidel algorithm has been developed employing waveform relaxation iterations for application to power grid networks. Proof of convergence of the proposed WR algorithm for power grid analysis is presented. Unlike direct solvers, the new method is highly parallelizable and yields significant speedups. Numerical examples are presented to demonstrate the validity and efficiency of the proposed method

Parallel and scalable transient simulator for power grids via waveform relaxation (PTS-PWR)

This paper presents a fast algorithm for transient simulation of power grids in very large scale integration systems using waveform relaxation (WR) techniques. Novel partitioning methods and convergence accelerators are developed for fast convergence of WR iterations when applied to power grid networks. Unlike the direct solvers, the new method is highly parallelizable and scales well with the increasing number of CPUs, leading to significant speed-ups. Numerical examples are presented to demonstrate the validity and e

Dissipative Forces in the Electrowetted Cassie-Wenzel Transition on Hydrophobic Rough Surfaces

Dissipative forces in the electrowetting-induced Cassie-Wenzel transition on hydrophobic rough surfaces are explored. High-speed imaging of droplet shape evolution during the elec- trically induced spreading process allows for the location of the contact line to be tracked as a function of time. A surface energy analysis quantifies the total energy dissipated via nonconservative forces during the spreading process. Though identified as the dominant dissipative effect in droplet spreading on smooth surfaces, contact line friction is shown to have a relatively weak influence on the spreading on rough surfaces. Supplemental files are available for this article. Go to the publisher’s online edition of Nanoscale and Microscale Thermophysical Engineering to view the free supplemental file