The young open cluster NGC 7067 using Stromgren photometry

© The Authors 2016. Published by Oxford University Press on behalf of The Royal Astronomical Society. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted reuse, distribution, and reproduction in any medium, provided the original work is properly cited. M. Monguio et al, ' The young open cluster NGC 7067 using Stromgren photometry ', MNRAS Vol 466(3): 3636-3647 (2017), first published online 17 December 2016, the version of record is available online via doi: 10.1093/mnras/stw3302NGC 7067 is a young open cluster located in the direction between the first and the second Galactic quadrants and close to the Perseus spiral arm. This makes it useful for studies of the nature of the Milky Way spiral arms. Stromgren photometry taken with the Wide Field Camera at the Isaac Newton Telescope allowed us to compute individual physical parameters for the bserved stars and hence to derive cluster’s physical parameters. Spectra from the 1.93-m telescope at the Observatoire de Haute-Provence helped to check and improve the results. We obtained photometry for 1233 stars, individual physical parameters for 515 and spectra for 9 of them. The 139 selected cluster members lead to a cluster distance of 4.4±0.4 kpc, with an age below log10(t(yr))=7.3 and a present Mass of 1260±160M⊙. The morphology of the data reveals that the centre of the cluster is at (α,δ)=(21: 24: 13.69,+48: 00: 39.2) J2000, with a radius of 6.′1. Stromgren and spectroscopic data allowed us to improve the previous parameters available for the cluster in the literature.Peer reviewedFinal Published versio

Altérations génétiques des cholinestérases chez des souris (conséquences morphologiques et fonctionnelles à la jonction neuromusculaire)

Au niveau de la jonction neuromusculaire (JNM) de Vertébrés, 2 enzymes peuvent hydrolyser l acétylcholine (ACh) : l acétylcholinestérase (AChE) et la butyrylcholinestérase (BChE). Nous disposons de plusieurs lignées de souris (AChE KO, AChE Del E5,6, AChE Del E5/neo et BChE KO) qui présentent un déficit dans l'hydrolyse de l'ACh. Ces mutations ont permis d analyser les conséquences fonctionnelles et morphologiques du déficit en AChE au niveau de la JNM et de comprendre le rôle de la BChE lors de la transmission synaptique. Malgré le déficit en AChE, les souris développent des contractions tétaniques dans une gamme de fréquence physiologique. Les cours temporels des réponses synaptiques enregistrées au niveau des JNM sont augmentés, ce qui traduit l activation répétitive des récepteurs nicotiniques à l ACh (RnACh) par l ACh malgré un remodelage pré et post-synaptique mis en évidence qui est probablement dû à l adaptation des RnACh face à l absence d activité enzymatique de l AChE.At the vertebrate neuromuscular junction, two enzymes can hydrolize acetylcholine (ACh): acetylcholinesterase (AChE) and butyrylcholinesterase (BChE). Advances in mouse genomics offers new approaches to assess the role of specific cholinesterases involved in neuromuscular transmission. We have several lines of mice which present a deficit in the hydrolysis of ACh at the neuromuscular junctions (NMJ). The functional and morphological consequences at the NMJ were analyzed by electrophysiological and confocal microscopy approaches. In spite of AChE deficient, mice develop tetanic contractions in physiological frequencies but cannot maintain them at high frequencies. Moreover, the pre and post-synaptic remodelling is probably due to the adaptation of ACh receptors nicotinic (AChR) and of the motor endplate in the absence of enzymatic activity of AChE.PARIS-Museum Hist.Naturelle (751052304) / SudocSudocFranceF

Etude du mode d'action de la toxine létale de Clostridium sordellii sur le système neuromusculaire squelettique de vertébrés

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Marine toxins potently affecting neurotransmitter release¹

ISBN: 978-3-540-87892-6Synapses are specialised structures where interneuronal communication takes place. Not only brain function is absolutely dependent on synaptic activity, but also most of our organs are intimately controlled by synaptic activity. Synapses re therefore an ideal target to act upon and poisonous species have evolved fascinating neurotoxins capable of shutting down neuronal communication by blocking or activating essential components of the synapse. By hijacking key proteins of the communication machinery, neurotoxins are therefore extremely valuable tools that have, in turn, greatly helped our understanding of synaptic biology. Moreover, analysis and understanding of the molecular strategy used by certain neurotoxins has allowed the design of entirely new classes of drugs acting on specific targets with high selectivity and efficacy. This chapter will discuss the different classes of marine neurotoxins, their effects on neurotransmitter release and how they act to incapacitate key steps in the process leading to synaptic vesicle fusion

Equinatoxin II increases intracellular Ca2+ in NG 108–15 cells

Equinatoxin II (EqT II) is a basic 20 kD protein isolated from the sea anemone Actinia equina. Intravenous injection of 3 LD of EqT II causes cardiorespiratory arrest. The aim of our study was to check the effects of EqT II on neuronal cells to assess the role of neuronal mechanisms in respiratory arrest after intravenous injection of the toxin. Effects of EqT II on mouse neuroblastoma x rat glioma NG108-15 cell were studied using confocal laser scanning microscopy and by Fura-2 fluorescence measurements. The results show that EqT II applied in nanomolar range increases intracellular Ca activity significantly, which is possibly responsible for the morphological changes of NG108-15 cells after the exposure to 10 nM EqT II. Intracellular increase in Ca activity can not be prevented by use of the various pharmacological substances (e.g. Ca channels blocker Verapamil and Bekanamycin). Swelling of the NG108-15 cells after the exposure to the EqT II also can not be blocked with the sodium channel blocker tetrodotoxin. Increase in the intracellular Ca activity is probably a result of Ca entry through pores produced by the toxin, which has been shown by other authors on other cells and on phospholipid bilayer. Respiratory arrest after intravenous injection of the toxin can be caused by the action of the toxin on neuronal cells in medulla oblongata provided that EqT II can damage blood brain barrier thus enabling access to the neuronal cells. The results allow the conclusion that EqT II can affect normal calcium homeostasis and cell morphology of neuronal cells that can disturb cell physiology and its function thus affecting normal respiratory pattern

Ciguatera toxins: Pharmacology of toxins involved in Ciguatera and related fish poisonings

The increased harvesting of tropical marine resources has contributed to an increased incidence of human intoxication associated with fish consumption. Of these fish poisonings, ciguatera is arguably the most significant, both in terms of the number and the severity of poisoning episodes. The disease is associated with the consumption of many species of tropical and subtropical fishes from the Indo-Pacific Oceans and Caribbean Sea that have become contaminated by ciguatoxins which arise from blooms of certain strains of the benthic dinoflagellate Gambierdiscus toxicus. Environmental degradation may play a role in the increased incidence of ciguatera, although the precise factors involved remain elusive. The role played by other marine toxins in ciguatera, including other toxins produced by benthic dinoflagellates, has not been demonstrated, although mild cases of palytoxin poisoning may be mistaken for ciguatera. Over the last decade there have been rapid advances in our knowledge of the precise chemical and pharmacological properties of the toxins which contribute to the different forms of fish poisoning, especially those toxins involved in ciguatera. Ciguatera can be defined as an illness caused by the consumption of polyether sodium channel activator toxins (ciguatoxins, CTXs) that accumulate to levels that cause acute human intoxication characterized by neurological, gastrointestinal, and cardiovascular disorders. The ciguatoxins are a family of lipid-soluble, highly oxygenated, cyclic polyether molecules

Biodiversity of the genus Conus (Fleming, 1822): a rich source of bioactive peptides

International audienceIn this paper, we present an overview of the biodiversity of both marine snails of the large genus Conus and their venoms. After a brief survey of Conidae malacology, we focus on the high degree of biodiversity of this genus, its specific biogeography as well as its habitat, and the relatively strict diet of its members. The venom of Conidae species contains a large number of peptides that can interact selectively with key elements of the peripheral and central nervous systems of vertebrates and invertebrates. Emphasis is on summarizing our current knowledge of the specific actions of venom components on ionic channels, receptors and other key elements of cellular communication. The peptides isolated from venoms, called conotoxins, form different families according to both their primary structure and their specific pharmacological targets. Three families encompassing the mu-, muO- and delta-conotoxins target voltage-sensitive sodium channels but with different modes of action or tissue selectivity. Another important class of conotoxins is the omega-conotoxin family which acts on voltage-sensitive calcium channels. The alpha-conotoxin family is represented by several peptides blocking muscular or neuronal nicotinic acetylcholine receptors. Finally, a blocker of potassium channels is presented as well as two conotoxins acting on the N-Methyl-D-Aspartate receptor. Primary structures and cysteine frameworks of all these conotoxins are shown and compared. At the end of the review, we report the contribution of molecular biology to identification of new conotoxins having original pharmacological properties. In conclusion, conotoxins have received increasing attention from physiologists, pharmacologists, biochemists and physicians because of their selectivity as well as their pharmacological and therapeutic potential

Biodiversity of the genus Conus (Fleming, 1822): a rich source of bioactive peptides

International audienceIn this paper, we present an overview of the biodiversity of both marine snails of the large genus Conus and their venoms. After a brief survey of Conidae malacology, we focus on the high degree of biodiversity of this genus, its specific biogeography as well as its habitat, and the relatively strict diet of its members. The venom of Conidae species contains a large number of peptides that can interact selectively with key elements of the peripheral and central nervous systems of vertebrates and invertebrates. Emphasis is on summarizing our current knowledge of the specific actions of venom components on ionic channels, receptors and other key elements of cellular communication. The peptides isolated from venoms, called conotoxins, form different families according to both their primary structure and their specific pharmacological targets. Three families encompassing the mu-, muO- and delta-conotoxins target voltage-sensitive sodium channels but with different modes of action or tissue selectivity. Another important class of conotoxins is the omega-conotoxin family which acts on voltage-sensitive calcium channels. The alpha-conotoxin family is represented by several peptides blocking muscular or neuronal nicotinic acetylcholine receptors. Finally, a blocker of potassium channels is presented as well as two conotoxins acting on the N-Methyl-D-Aspartate receptor. Primary structures and cysteine frameworks of all these conotoxins are shown and compared. At the end of the review, we report the contribution of molecular biology to identification of new conotoxins having original pharmacological properties. In conclusion, conotoxins have received increasing attention from physiologists, pharmacologists, biochemists and physicians because of their selectivity as well as their pharmacological and therapeutic potential