The Many Hats of Sonic Hedgehog Signaling in Nervous System Development and Disease.

Sonic hedgehog (Shh) signaling occurs concurrently with the many processes that constitute nervous system development. Although Shh is mostly known for its proliferative and morphogenic action through its effects on neural stem cells and progenitors, it also contributes to neuronal differentiation, axonal pathfinding and synapse formation and function. To participate in these diverse events, Shh signaling manifests differently depending on the maturational state of the responsive cell, on the other signaling pathways regulating neural cell function and the environmental cues that surround target cells. Shh signaling is particularly dynamic in the nervous system, ranging from canonical transcription-dependent, to non-canonical and localized to axonal growth cones. Here, we review the variety of Shh functions in the developing nervous system and their consequences for neurodevelopmental diseases and neural regeneration, with particular emphasis on the signaling mechanisms underlying Shh action

Mapping the Integration of Sensory Information across Fingers in Human Sensorimotor Cortex

The integration of somatosensory signals across fingers is essential for dexterous object manipulation. Previous experiments suggest that this integration occurs in neural populations in the primary somatosensory cortex (S1). However, the integration process has not been fully characterized, as previous studies have mainly used 2-finger stimulation paradigms. Here, we addressed this gap by stimulating all 31 single- and multifinger combinations. We measured population-wide activity patterns evoked during finger stimulation in human S1 and primary motor cortex (M1) using 7T fMRI in female and male participants. Using multivariate fMRI analyses, we found clear evidence of unique nonlinear interactions between fingers. In Brodmann area (BA) 3b, interactions predominantly occurred between pairs of neighboring fingers. In BA 2, however, we found equally strong interactions between spatially distant fingers, as well as interactions between finger triplets and quadruplets. We additionally observed strong interactions in the hand area of M1. In both M1 and S1, these nonlinear interactions did not reflect a general suppression of overall activity, suggesting instead that the interactions we observed reflect rich, nonlinear integration of sensory inputs from the fingers. We suggest that this nonlinear finger integration allows for a highly flexible mapping from finger sensory inputs to motor responses that facilitates dexterous object manipulation.SIGNIFICANCE STATEMENT Processing of somatosensory information in primary somatosensory cortex (S1) is essential for dexterous object manipulation. To successfully handle an object, the sensorimotor system needs to detect complex patterns of haptic information, which requires the nonlinear integration of sensory inputs across multiple fingers. Using multivariate fMRI analyses, we characterized brain activity patterns evoked by stimulating all single- and multifinger combinations. We report that progressively stronger multifinger interactions emerge in posterior S1 and in the primary motor cortex (M1), with interactions arising between inputs from neighboring and spatially distant fingers. Our results suggest that S1 and M1 provide the neural substrate necessary to support a flexible mapping from sensory inputs to motor responses of the hand

An in situ XAS study of the cobalt rhenium catalyst for ammonia synthesis

A cobalt rhenium catalyst active for ammonia synthesis at 400 °C and ambient pressure was studied using in situ XAS to elucidate the reducibility and local environment of the two metals during reaction conditions. The ammonia reactivity is greatly affected by the gas mixture used in the pre-treatment step. Following H2/Ar pre-treatment, a subsequent 20 min induction period is also observed before ammonia production occurs whereas ammonia production commences immediately following comparable H2/N2 pre-treatment. In situ XAS at the Co K-edge and Re LIII-edge show that cobalt initiates reduction, undergoing reduction between 225 and 300 °C, whereas reduction of rhenium starts at 300 °C. The reduction of rhenium is near complete below 400 °C, as also confirmed by H2-TPR measurements. A synergistic co-metal effect is observed for the cobalt rhenium system, as complete reduction of both cobalt and rhenium independently requires higher temperatures. The phases present in the cobalt rhenium catalyst during ammonia production following both pre-treatments are largely bimetallic Co–Re phases, and also monometallic Co and Re phases. The presence of nitrogen during the reduction step strongly promotes mixing of the two metals, and the bimetallic Co–Re phase is believed to be a pre-requisite for activity

Rapid assembly of highly-functionalised difluorinated cyclooctenones via ring-closing metathesis

Building block methodology from trifluoroethanol and ringclosing metathesis using a Fürstner modification of Grubbs’ conditions allows the rapid synthesis of novel difluorinated cyclooctenones

<i>meta</i>-Selective olefination of fluoroarenes with alkynes using CO₂ as a traceless directing group.

From Europe PMC via Jisc Publications RouterHistory: ppub 2020-03-01, epub 2020-03-31Publication status: PublishedFunder: Engineering and Physical Sciences Research Council; Grant(s): EP/L014017/2Over the last few decades C-H olefination has received significant interest, due to the importance and usefulness of aryl olefins both as synthetic targets and intermediates. While a wide range of ortho-olefination protocols have been developed, only a small number of meta-olefinations are currently available. Importantly, the most common approach to meta-olefination, using a large meta-directing template, is not suitable for substrates such as fluorobenzenes, which cannot be derivatised. We report that the meta-selective olefination of fluoroarenes can be achieved via the use of CO2 as a traceless directing group, which can be easily installed and removed in a one-pot process. Furthermore, this approach avoids the use of stoichiometric Ag(i)-salts, commonly used in C-H olefinations, and affords complete meta- over ortho/para-regioselectivity

Hybrid Iterative Approach for Simulation of Radio-frequency Fields in Plasma

A novel iterative approach for solving discretized linear wave equations in a frequency domain, which combines time evolution with iterative relaxation schemes, is presented. In this hybrid approach, each iteration cycle consists of evolution of electromagnetic (EM) fields in time over a specified number of field periods followed by several iterative relaxations. Provided that there is sufficient dissipation, both the time evolution and the iterative relaxations contribute to the convergence of the EM fields to the solution of the formulated full wave boundary value problem. Time evolution rapidly distributes EM fields, propagating with group velocity, over the simulation domain, while the iterative relaxations smooth the fields, reducing the numerical errors such that iteration cycles converge to a steady state solution, approximating the solution of the formulated problem. This approach is intended for large scale simulations which are beyond the capabilities of direct solvers presently used for solving wave equations in the frequency domain. The technique is demonstrated for solving wave equations on a regular grid using a cold plasma dielectric model with collisions for 2D modeling of EM fields in tokamak in an electron cyclotron frequency range

Understanding the Role of Host Hemocytes in a Squid/Vibrio Symbiosis Using Transcriptomics and Proteomics

The symbiosis between the squid, Euprymna scolopes, and the bacterium, Vibrio fischeri, serves as a model for understanding interactions between beneficial bacteria and animal hosts. The establishment and maintenance of the association is highly specific and depends on the selection of V. fischeri and exclusion of non-symbiotic bacteria from the environment. Current evidence suggests that the host’s cellular innate immune system, in the form of macrophage-like hemocytes, helps to mediate host tolerance of V. fischeri. To begin to understand the role of hemocytes in this association, we analyzed these cells by high-throughput 454 transcriptomic and liquid chromatography/tandem mass spectrometry (LC-MS/MS) proteomic analyses. 454 high-throughput sequencing produced 650, 686 reads totaling 279.9 Mb while LC-MS/MS analyses of circulating hemocytes putatively identified 702 unique proteins. Several receptors involved with the recognition of microbial-associated molecular patterns were identified. Among these was a complete open reading frame to a putative peptidoglycan recognition protein (EsPGRP5) with conserved residues for amidase activity. Assembly of the hemocyte transcriptome showed EsPGRP5 had high coverage, suggesting it is among the 5% most abundant transcripts in circulating hemocytes. Other transcripts and proteins identified included members of the conserved NF-κB signaling pathway, putative members of the complement pathway, the carbohydrate binding protein galectin, and cephalotoxin. Quantitative Real-Time PCR of complement-like genes, cephalotoxin, EsPGRP5, and a nitric oxide synthase showed differential expression in circulating hemocytes from adult squid with colonized light organs compared to those isolated from hosts where the symbionts were removed. These data suggest that the presence of the symbiont influences gene expression of the cellular innate immune system of E. scolopes

A two-qubit engine fueled by entangling operations and local measurements

We introduce a two-qubit engine that is powered by entangling operations and projective local quantum measurements. Energy is extracted from the detuned qubits coherently exchanging a single excitation. This engine, which uses the information and back-action of the measurement, is generalized to an N-qubit chain. We show that by gradually increasing the energy splitting along the chain, the initial low energy of the first qubit can be up-converted deterministically to an arbitrarily high energy at the last qubit by successive neighbor swap operations and local measurements. Modeling the local measurement as the entanglement of a qubit with a meter, we identify the measurement fuel as the energetic cost to erase correlations between the qubits.Comment: 5 pages, 4 figure

Albedos and diameters of three Mars Trojan asteroids

We observed the Mars Trojan asteroids (5261) Eureka and (101429) 1998 VF31 and the candidate Mars Trojan 2001 FR127 at 11.2 and 18.1 microns using Michelle on the Gemini North telescope. We derive diameters of 1.28, 0.78, and <0.52 km, respectively, with corresponding geometric visible albedos of 0.39, 0.32, and >0.14. The albedos for Eureka and 1998 VF31 are consistent with the taxonomic classes and compositions (S(I)/angritic and S(VII)/achrondritic, respectively) and implied histories presented in a companion paper by Rivkin et al. Eureka's surface likely has a relatively high thermal inertia, implying a thin regolith that is consistent with predictions and the small size that we derive.Comment: Icarus, in press. See companion paper 0709.1925 by Rivkin et al; two minor typos fixe