Dark Matter and Fundamental Physics with the Cherenkov Telescope Array

The Cherenkov Telescope Array (CTA) is a project for a next-generation observatory for very high energy (GeV-TeV) ground-based gamma-ray astronomy, currently in its design phase, and foreseen to be operative a few years from now. Several tens of telescopes of 2-3 different sizes, distributed over a large area, will allow for a sensitivity about a factor 10 better than current instruments such as H.E.S.S, MAGIC and VERITAS, an energy coverage from a few tens of GeV to several tens of TeV, and a field of view of up to 10 deg. In the following study, we investigate the prospects for CTA to study several science questions that influence our current knowledge of fundamental physics. Based on conservative assumptions for the performance of the different CTA telescope configurations, we employ a Monte Carlo based approach to evaluate the prospects for detection. First, we discuss CTA prospects for cold dark matter searches, following different observational strategies: in dwarf satellite galaxies of the Milky Way, in the region close to the Galactic Centre, and in clusters of galaxies. The possible search for spatial signatures, facilitated by the larger field of view of CTA, is also discussed. Next we consider searches for axion-like particles which, besides being possible candidates for dark matter may also explain the unexpectedly low absorption by extragalactic background light of gamma rays from very distant blazars. Simulated light-curves of flaring sources are also used to determine the sensitivity to violations of Lorentz Invariance by detection of the possible delay between the arrival times of photons at different energies. Finally, we mention searches for other exotic physics with CTA.Comment: (31 pages, Accepted for publication in Astroparticle Physics

The grapevine uncharacterized intrinsic protein 1 (VvXIP1) is regulated by drought stress and transports glycerol, hydrogen peroxide, heavy metals but not water

A MIP (Major Intrinsic Protein) subfamily called Uncharacterized Intrinsic Proteins (XIP) was recently described in several fungi and eudicot plants. In this work, we cloned a XIP from grapevine, VvXIP1, and agrobacterium-mediated transformation studies in Nicotiana benthamiana revealed that the encoded aquaporin shows a preferential localization at the endoplasmic reticulum membrane. Stopped-flow spectrometry in vesicles from the aqy-null yeast strain YSH1172 overexpressing VvXIP1 showed that VvXIP1 is unable to transport water but is permeable to glycerol. Functional studies with the ROS sensitive probe CM-H(2)DCFDA in intact transformed yeasts showed that VvXIP1 is also able to permeate hydrogen peroxide (H2O2). Drop test growth assays showed that besides glycerol and H2O2, VvXIP1 also transports boric acid, copper, arsenic and nickel. Furthermore, we found that VvXIP1 transcripts were abundant in grapevine leaves from field grown plants and strongly repressed after the imposition of severe water-deficit conditions in potted vines. The observed downregulation of VvXIP1 expression in cultured grape cells in response to ABA and salt, together with the increased sensitivity to osmotic stress displayed by the aqy-null yeast overexpressing VvXIP1, corroborates the role of VvXIP1 in osmotic regulation besides its involvement in H2O2 transport and metal homeostasis.This work was supported by European Union Funds (FEDER/COMPETE Operational Competitiveness Programme) and Portuguese national Funds (FCT-Portuguese Foundation for Science and Technology): KBBE-2012-6-3117 "Inovinne", FCOMP-01-0124-FEDER-022692 and PTDC/AGR-ALI/100636/2008. HN (SFRH/BD/74257/2010) and APM (SFRH/BD/65046/2009) were supported by PhD grants from FCT. The Interuniversity Attraction Poles Programme-Belgian Science Policy (IAP7/29) and the Belgian French community ARC11/16-036 project.info:eu-repo/semantics/publishedVersio

Obesity, Fat Mass and Immune System: Role for Leptin

Obesity is an epidemic disease characterized by chronic low-grade inflammation associated with a dysfunctional fat mass. Adipose tissue is now considered an extremely active endocrine organ that secretes cytokine-like hormones, called adipokines, either pro- or anti-inflammatory factors bridging metabolism to the immune system. Leptin is historically one of most relevant adipokines, with important physiological roles in the central control of energy metabolism and in the regulation of metabolism-immune system interplay, being a cornerstone of the emerging field of immunometabolism. Indeed, leptin receptor is expressed throughout the immune system and leptin has been shown to regulate both innate and adaptive immune responses. This review discusses the latest data regarding the role of leptin as a mediator of immune system and metabolism, with particular emphasis on its effects on obesity-associated metabolic disorders and autoimmune and/or inflammatory rheumatic diseases.OG is Staff Personnel of Xunta de Galicia (Servizo Galego de Saude, SERGAS) through a research-staff stabilization contract (ISCIII/SERGAS). VF is a “Sara Borrell” Researcher funded by ISCIII and FEDER. RG is a “Miguel Servet” Researcher funded by Instituto de Salud Carlos III (ISCIII) and FEDER. OG, MG-G, and RG are members of RETICS Program, RD16/0012/0014 (RIER: Red de Investigación en Inflamación y Enfermedades Reumáticas) via Instituto de Salud Carlos III (ISCIII) and FEDER. The work of OG and JP (PIE13/00024 and PI14/00016, PI17/00409), and RG (PI16/01870 and CP15/00007) was funded by Instituto de Salud Carlos III and FEDER. OG is a beneficiary of a project funded by Research Executive Agency of the European Union in the framework of MSCA-RISE Action of the H2020 Program (Project No. 734899). The funders had no role in study design, data collection, and analysis, decision to publish, or preparation of the manuscript

Presynaptic morphology and vesicular composition determine vesicle dynamics in mouse central synapses

Transport of synaptic vesicles (SVs) in nerve terminals is thought to play essential roles in maintenance of neurotransmission. To identify factors modulating SV movements, we performed real-time imaging analysis of fluorescently labeled SVs in giant calyceal and conventional hippocampal terminals. Compared with small hippocampal terminals, SV movements in giant calyceal terminals were faster, longer and kinetically more heterogeneous. Morphological maturation of giant calyceal terminals was associated with an overall reduction in SV mobility and displacement heterogeneity. At the molecular level, SVs over-expressing vesicular glutamate transporter 1 (VGLUT1) showed higher mobility than VGLUT2-expressing SVs. Pharmacological disruption of the presynaptic microtubule network preferentially reduced long directional movements of SVs between release sites. Functionally, synaptic stimulation appeared to recruit SVs to active zones without significantly altering their mobility. Hence, the morphological features of nerve terminals and the molecular signature of vesicles are key elements determining vesicular dynamics and movements in central synapses