RIM-binding proteins recruit BK-channels to presynaptic release sites adjacent to voltage-gated Ca2+-channels.

The active zone of presynaptic nerve terminals organizes the neurotransmitter release machinery, thereby enabling fast Ca2+-triggered synaptic vesicle exocytosis. BK-channels are Ca2+-activated large-conductance K+-channels that require close proximity to Ca2+-channels for activation and control Ca2+-triggered neurotransmitter release by accelerating membrane repolarization during action potential firing. How BK-channels are recruited to presynaptic Ca2+-channels, however, is unknown. Here, we show that RBPs (for RIM-binding proteins), which are evolutionarily conserved active zone proteins containing SH3- and FN3-domains, directly bind to BK-channels. We find that RBPs interact with RIMs and Ca2+-channels via their SH3-domains, but to BK-channels via their FN3-domains. Deletion of RBPs in calyx of Held synapses decreased and decelerated presynaptic BK-currents and depleted BK-channels from active zones. Our data suggest that RBPs recruit BK-channels into a RIM-based macromolecular active zone complex that includes Ca2+-channels, synaptic vesicles, and the membrane fusion machinery, thereby enabling tight spatio-temporal coupling of Ca2+-influx to Ca2+-triggered neurotransmitter release in a presynaptic terminal.

Room-temperature voltage tunable phonon thermal conductivity via reconfigurable interfaces in ferroelectric thin films.

Dynamic control of thermal transport in solid-state systems is a transformative capability with the promise to propel technologies including phononic logic, thermal management, and energy harvesting. A solid-state solution to rapidly manipulate phonons has escaped the scientific community. We demonstrate active and reversible tuning of thermal conductivity by manipulating the nanoscale ferroelastic domain structure of a Pb(Zr0.3Ti0.7)O3 film with applied electric fields. With subsecond response times, the room-temperature thermal conductivity was modulated by 11%.

Revealing Plasma Membrane Nano-Domains with Diffusion Analysis Methods.

Nano-domains are sub-light-diffraction-sized heterogeneous areas in the plasma membrane of cells, which are involved in cell signalling and membrane trafficking. Throughout the last thirty years, these nano-domains have been researched extensively and have been the subject of multiple theories and models: the lipid raft theory, the fence model, and the protein oligomerization theory. Strong evidence exists for all of these, and consequently they were combined into a hierarchal model. Measurements of protein and lipid diffusion coefficients and patterns have been instrumental in plasma membrane research and by extension in nano-domain research. This has led to the development of multiple methodologies that can measure diffusion and confinement parameters including single particle tracking, fluorescence correlation spectroscopy, image correlation spectroscopy and fluorescence recovery after photobleaching. Here we review the performance and strengths of these methods in the context of their use in identification and characterization of plasma membrane nano-domains.

Nano-Domains Produced through a Two-Step Poling Technique in Lithium Niobate on Insulators.

We proposed a two-step poling technique to fabricate nanoscale domains based on the anti-parallel polarization reversal effect in lithium niobate on insulator (LNOI). The anti-parallel polarization reversal is observed when lithium niobate thin film in LNOI is poled by applying a high voltage pulse through the conductive probe tip of atomic force microscope, which generates a donut-shaped domain structure with its domain polarization at the center being anti-parallel to the poling field. The donut-shaped domain is unstable and decays with a time scale of hours. With the two-step poling technique, the polarization of the donut-shaped domain can be reversed entirely, producing a stable dot domain with a size of tens of nanometers. Dot domains with diameter of the order of ∼30 nm were fabricated through the two-step poling technique. The results may be beneficial to domain-based applications such as ferroelectric domain memory.