Beyond membrane curvature: Clade 6 reticulons and their role within the plant endoplasmic reticulum

The endoplasmic reticulum (ER) is a dynamic organelle with multiple functions. It is comprised of distinct morphological domains. Regulation of this morphology and its dynamics are mediated by several highly conserved families of proteins, namely the reticulon (RTN) proteins responsible for generating high curvature membranes, Lunapark (LNP) proteins mediating cisternae formation, and ROOT HAIR DEFECTIVE 3 (RHD3/Atlastin/Sey1p) which is required for 3-way junction formation. The differential expression of these proteins induces changes in ER morphology, and morphological dysregulation has been associated with disruptions in overall cellular function. Within the Arabidopsis genome, there are 21 RTN genes, across 6 protein clades. Clade 1-4 RTNs have been demonstrated to induce tubule formation, and upon over-expression produce a hyperconstriction phenotype on ER tubules. This function is mediated via the reticulon homology domain (RHD), which contains 4 transmembrane domains (TMDs). The ‘W’ shaped topology allows the RTNs to induce hydrophobic wedging and subsequent curvature of the ER membrane, and which is stabilised via oligomerisation of RTNs. Clade 5 RTNs, were previously characterised and found to localise distinctly different to clade 1-4 RTNs and are involved in regulation of sterol contents in roots due to the presence of a 3β-hydroxysteroid dehydrogenase domain (3βHSD). In this body of work, the three members of clade 6 RTNs are characterised for the first time, revealing that RTN17, RTN18 and RTN21 localise to distinct punctate structures across the ER network. Analysis of RTN17.1 interacting partners indicates it could act as a hub protein utilising intrinsically disordered termini to interact with RHD3, and associates with the cytoskeletal network to promote homotypic fusion within the ER. Clade 6 RTNs are functionally distinct from clade 1-5 RTNs, and quantitative analysis of over-expression phenotypes reveal a distinct morphological profile linked to their suggested role in 3-way junction formation

Nonlinear femtosecond pulse propagation in an all-solid photonic bandgap fiber

Nonlinear femtosecond pulse propagation in an all-solid photonic bandgap fiber is experimentally and numerically investigated. Guiding light in such fiber occurs via two mechanisms: photonic bandgap in the central silica core or total internal reflection in the germanium doped inclusions. By properly combining spectral filtering, dispersion tailoring and pump coupling into the fiber modes, we experimentally demonstrate efficient supercontinuum generation with controllable spectral bandwidth

Fracture properties of CrN hard coatings: Influence of the microstructure, alloying elements, and coating architecture

Transition metal nitrides are well known and applied as protective coating materials based on their unique refractory characteristics, such as high hardness or Young’s modulus. However, for long-term applications, the fracture toughness KIC is an essential factor as the integrity of the coating-substrate interface is impaired by cracking and subsequent environmental attacks. Please click Download on the upper right corner to see the full abstract

intER-ACTINg: the structure and dynamics of ER and actin are interlinked

The actin cytoskeleton is the driver of gross ER remodelling and the move-mentandpositioning of othermembrane-boundorganellessuchasGolgibodies.Rapid ER membrane remodelling is a feature of most plant cells and is importantfor normal cellular processes, including targeted secretion, immunity and sig-nalling. Modifications to the actin cytoskeleton through pharmacological agentssuch as Latrunculin B and phalloidin, or disruption of normal myosin func-tion also affect ER structure and/or dynamics. Here, we investigate the impactof changes in the actin cytoskeleton on structure and dynamics on the ER aswell as in return the impact of modified ER structure on the architecture of theactin cytoskeleton. By expressing actin markers that affect actin dynamics, orexpressing of ER-shaping proteins that influence ER architecture, we found thatthe structure of ER-actin networks is closely inter-related; affecting one compo-nent is likely to have a direct effect on the other. Therefore, our results indicatethat a complicated regulatory machinery and cross-talk between these two struc-tures must exist in plants to co-ordinate the function of ER-actin network duringmultiple subcellular processes. In addition, when considering organelle struc-tureanddynamics,thechoiceofactinmarkerisessentialinpreventingoff-targetorganelle structure and dynamics modifications

The olfactory bulb is a source of high-frequency oscillations (130–180 Hz) associated with a subanesthetic dose of ketamine in rodents

High-frequency neuronal population oscillations (HFO, 130–180 Hz) are robustly potentiated by subanesthetic doses of ketamine. This frequency band has been recorded in functionally and neuroanatomically diverse cortical and subcortical regions, notably ventral striatal areas. However, the locus of generation remains largely unknown. There is compelling evidence that olfactory regions can drive oscillations in distant areas. Here we tested the hypothesis that the olfactory bulb (OB) is a locus for the generation of HFO following a subanesthetic dose of ketamine. The effect of ketamine on the electrophysiological activity of the OB and ventral striatum of male Wistar rats was examined using field potential and unit recordings, local inhibition, naris blockade, current source density and causality estimates. Ketamine-HFO was of larger magnitude and was phase-advanced in the OB relative to ventral striatum. Granger causality analysis was consistent with the OB as the source of HFO. Unilateral local inhibition of the OB and naris blockade both attenuated HFO recorded locally and in the ventral striatum. Within the OB, current source density analysis revealed HFO current dipoles close to the mitral layer and unit firing of mitral/tufted cells was phase locked to HFO. Our results reveal the OB as a source of ketamine-HFO which can contribute to HFO in the ventral striatum, known to project diffusely to many other brain regions. These findings provide a new conceptual understanding on how changes in olfactory system function may have implications for neurological disorders involving NMDA receptor dysfunction such as schizophrenia and depression

PuLSE:Quality control and quantification of peptide sequences explored by phage display libraries

The design of highly diverse phage display libraries is based on assumption that DNA bases are incorporated at similar rates within the randomized sequence. As library complexity increases and expected copy numbers of unique sequences decrease, the exploration of library space becomes sparser and the presence of truly random sequences becomes critical. We present the program PuLSE (Phage Library Sequence Evaluation) as a tool for assessing randomness and therefore diversity of phage display libraries. PuLSE runs on a collection of sequence reads in the fastq file format and generates tables profiling the library in terms of unique DNA sequence counts and positions, translated peptide sequences, and normalized 'expected' occurrences from base to residue codon frequencies. The output allows at-a-glance quantitative quality control of a phage library in terms of sequence coverage both at the DNA base and translated protein residue level, which has been missing from toolsets and literature. The open source program PuLSE is available in two formats, a C++ source code package for compilation and integration into existing bioinformatics pipelines and precompiled binaries for ease of use

Borexino : geo-neutrino measurement at Gran Sasso, Italy

Geo-neutrinos, electron anti-neutrinos produced in beta-decays of naturally occurring radioactive isotopes in the Earth, are a unique direct probe of our planet's interior. After a brief introduction of the geo-neutrinos' properties and of the main aims of their study, we discuss the features of a detector which has recently provided breakthrough achievements in the field, Borexino, a massive, calorimetric liquid scintillator detector installed at the underground Gran Sasso Laboratory. With its unprecedented radiopurity levels achieved in the core of the detection medium, it is the only experiment in operation able to study in real time solar neutrino interactions in the challenging sub-MeV energy region. Its superior technical properties allowed Borexino also to provide a clean detection of terrestrial neutrinos. Therefore, the description of the characteristics of the detected geo-neutrino signal and of the corresponding geological implications are the main core of the discussion contained in this work