Non-hyperpolarizing GABA B receptor activation regulates neuronal migration and neurite growth and specification by cAMP/LKB1

γ-Aminobutyric acid is the principal inhibitory neurotransmitter in adults, acting through ionotropic chloride-permeable GABAA receptors (GABAARs), and metabotropic GABABRs coupled to calcium or potassium channels, and cyclic AMP signalling. During early development, γ-aminobutyric acid is the main neurotransmitter and is not hyperpolarizing, as GABAAR activation is depolarizing while GABABRs lack coupling to potassium channels. Despite extensive knowledge on GABAARs as key factors in neuronal development, the role of GABABRs remains unclear. Here we address GABABR function during rat cortical development by in utero knockdown (short interfering RNA) of GABABR in pyramidal-neuron progenitors. GABABR short interfering RNA impairs neuronal migration and axon/dendrite morphological maturation by disrupting cyclic AMP signalling. Furthermore, GABABR activation reduces cyclic AMP-dependent phosphorylation of LKB1, a kinase involved in neuronal polarization, and rescues LKB1 overexpression-induced defects in cortical development. Thus, non-hyperpolarizing activation of GABABRs during development promotes neuronal migration and morphological maturation by cyclic AMP/LKB1 signalling

Polarized Expression of p75NTR Specifies Axons during Development and Adult Neurogenesis

VIDEO ABSTRACT: Newly generated neurons initiate polarizing signals that specify a single axon and multiple dendrites, a process critical for patterning neuronal circuits in vivo. Here, we report that the pan-neurotrophin receptor p75(NTR) is a polarity regulator that localizes asymmetrically in differentiating neurons in response to neurotrophins and is required for specification of the future axon. In cultured hippocampal neurons, local exposure to neurotrophins causes early accumulation of p75(NTR) into one undifferentiated neurite to specify axon fate. Moreover, knockout or knockdown of p75(NTR) results in failure to initiate an axon in newborn neurons upon cell-cycle exit in vitro and in the developing cortex, as well as during adult hippocampal neurogenesis in vivo. Hence, p75(NTR) governs neuronal polarity, determining pattern and assembly of neuronal circuits in adult hippocampus and cortical development

The three-electrode device: A new frontier for the in utero electroporation

The understanding of brain function requires the development of new methods to perturb and track distinct neuronal populations in the developing and adult central nervous system. Over the past ten years, in utero electroporation (IUE) has arisen as an extremely powerful tool to transfect and manipulate neuronal precursor cells of the parietal-cortex and their progeny in vivo. Although this technique has tremendous potentialities in targeting numerous brain areas, the results obtained so far have been generally hindered by low reliability of transfection in some regions and by the physical impossibility to reach other regions. Here, we present an innovative IUE configuration, which allows highly reliable transfection at various brain locations, including regions and cell types never targeted before. Our device, based on the usage of three independent electrodes upon an easy and highly reliable re-orientation of the electrode’s positions and polarities, allows consistent expression of genes of interest in an array of brain areas including the hippocampus, the visual and motor cortices, and the cerebellum. Moreover, depending on the developmental stage of the embryos, it is possible to target distinct neuronal cell types, which may be particularly relevant in the cerebellum. The importance of such a tool in comparison to other methods arises in those particular applications where tissues and circuits integrity are essential points, and in those where traditional electroporation configuration is the limiting step of the experimental approach

High-performance and site-directed in utero electroporation by a triple-electrode probe

In utero electroporation is a powerful tool to transfect and manipulate neural-precursor cells of the rodent parietal cortex and their progeny in vivo. Although this technique can potentially target numerous brain areas, reliability of transfection in some brain regions is low or physical access is limited. Here we present a new in utero electroporation configuration based on the use of three electrodes, the relative position and polarities of which can be adjusted. The technique allows easy access and exceedingly reliable monolateral or bilateral transfection at brain locations that could only be sporadically targeted before. By improvement in the efficiency of the electrical field distribution, demonstrated here by a mathematical simulation, the multi-electrode configuration also extends the developmental timeframe for reliable in utero electroporation, allowing for the first time specific transfection of Purkinje cells in the rat cerebellum

Joint Observation of the Galactic Center with MAGIC and CTA-LST-1

MAGIC is a system of two Imaging Atmospheric Cherenkov Telescopes (IACTs), designed to detect very-high-energy gamma rays, and is operating in stereoscopic mode since 2009 at the Observatorio del Roque de Los Muchachos in La Palma, Spain. In 2018, the prototype IACT of the Large-Sized Telescope (LST-1) for the Cherenkov Telescope Array, a next-generation ground-based gamma-ray observatory, was inaugurated at the same site, at a distance of approximately 100 meters from the MAGIC telescopes. Using joint observations between MAGIC and LST-1, we developed a dedicated analysis pipeline and established the threefold telescope system via software, achieving the highest sensitivity in the northern hemisphere. Based on this enhanced performance, MAGIC and LST-1 have been jointly and regularly observing the Galactic Center, a region of paramount importance and complexity for IACTs. In particular, the gamma-ray emission from the dynamical center of the Milky Way is under debate. Although previous measurements suggested that a supermassive black hole Sagittarius A* plays a primary role, its radiation mechanism remains unclear, mainly due to limited angular resolution and sensitivity. The enhanced sensitivity in our novel approach is thus expected to provide new insights into the question. We here present the current status of the data analysis for the Galactic Center joint MAGIC and LST-1 observations

Drainback solar thermal systems in Switzerland ::market overview and main barriers

During the last years, solar thermal systems have lost in attractiveness mostly due to their high initial installation costs, higher complexity compared to photovoltaic systems and a regular need of maintenance to avoid overheating and freezing problems, e.g. control of glycol mixture properties. Drainback (DB) solar thermal systems may overcome some of these issues and contribute to the market recovery as it prevents overheating and freezing of the solar system components even when pure water is used as the heat carrier fluid. It also needs less components than classical pressurised systems, which leads to less complex, lower system costs. Nevertheless, this type of system has not been very successful in Switzerland, only accounting for a small part of the market. In order to identify the barriers preventing the wide Swiss acceptance of DB systems, a literature review was performed and an online survey conducted and addressed to the different actors of the solar thermal sector. The aim is to understand the reasons of low market penetration of DB systems in Switzerland and to clearly identify the main barriers to its spreading. Results show that investments in research, product development, technology demonstration and market deployment in the form of professional training and technology information are essential to promote the DB in Switzerland

Endogenous noise of neocortical neurons correlates with atypical sensory response variability in the Fmr1 −/y mouse model of autism

Abstract Excessive neural variability of sensory responses is a hallmark of atypical sensory processing in autistic individuals with cascading effects on other core autism symptoms but unknown neurobiological substrate. Here, by recording neocortical single neuron activity in a well-established mouse model of Fragile X syndrome and autism, we characterized atypical sensory processing and probed the role of endogenous noise sources in exaggerated response variability in males. The analysis of sensory stimulus evoked activity and spontaneous dynamics, as well as neuronal features, reveals a complex cellular and network phenotype. Neocortical sensory information processing is more variable and temporally imprecise. Increased trial-by-trial and inter-neuronal response variability is strongly related to key endogenous noise features, and may give rise to behavioural sensory responsiveness variability in autism. We provide a novel preclinical framework for understanding the sources of endogenous noise and its contribution to core autism symptoms, and for testing the functional consequences for mechanism-based manipulation of noise

Optimization and validation of extraction and quantification methods of antimalarial triterpenic esters in Keetia leucantha plant and plasma

The aim of this study is to develop validated methods for the extraction and quantification of antimalarial triterpene esters from Keetia leucantha and from plasma samples. These compounds, showing in vitro and in vivo antiplasmodial activities, were optimally extracted from Keetia leucantha twigs using ultrasounds with dichloromethane and from plasma using protein precipitation with acetonitrile. We then developed and validated HPLC-UV quantification methods, which proved to be selective, accurate, linear, true and precise, both in plant and plasma samples for the eight triterpenic esters in mixture. Based on the total error concept as decision criteria, the validated dosage ranges of the triterpene esters mixture were set between 14.68 and 73.37 μg/mL in plants and 15.90 and 106.01 μg/mL in plasma injected solutions, corresponding to 7.95 and 53.01 μg/mL in plasma. These reliable methods were used to determine effectively triterpene esters content in collected samples, that seems highly variable in plant extracts, and will be helpful to further investigate pharmacokinetics parameters of these interesting bioactive compounds

Development of a vacuum insulated thermal energy storage for industrial applications

In this article the development of a high performance, double-wall vacuum insulated thermal energy storage for high temperature applications is presented. In this concept, the main heat losses of the tank are limited to radiation and to the thermal bridges present in the wall of the tank and fittings. This concept is well suited for high temperature applications such as those found in the industrial sector where storage energy losses are an important issue. Few studies on double wall evacuated tanks were found in the open literature and none employed a completely evacuated gap as proposed in this study. A structural analysis was performed to validate the proposed design and ensure conformity to high temperature applications. Preliminary heat transfer calculations assessed the impact of low emissivity coatings on the radiative heat transport in the evacuated gap. A numerical model of the container was developed and the thermal behaviour investigated under different operating conditions