Articles

Sensitivity of cardiac background inward rectifying K+ outward current (IK1) to the alkaloids lepadiformines A, B, and C
- Sauviat Martin-Pierre
- Vercauteren J.
- Grimaud N.
- Jugé M.
- Nabil M.
- Petit J.-Y.
- Biard J.-F.
Journal of Natural Products, American Chemical Society , 2006, 69 (4), pp.558 . Three marine alkaloids, purified from Clavelina moluccensis, were structurally identified as lepadiformines A, B, and C and studied on frog atrial myocytes IK1, using the patch-clamp technique. Lepadiformine A (0.4 to 3.3 μM) blocked IK1 dose-dependently with an apparent dissociation constant (KD) equal to 1.42 μM and a stoichiometry of 0.77. The block is voltage-dependent, suggesting that lepadiformine A occupies a receptor site located at about two-thirds of the membrane depth. The shortening of the aliphatic chain at position C13 of lepadiformine B decreased the potency of the molecule to block IK1 but not the affinity (KD = 1.56 μM) and stoichiometry (0.72). Additional deletion of the oxygenated side chain at C2 in lepadiformine C markedly decreased the inhibitory effect of the molecule. In conclusion, lepadiformine modulates IK1 response in cardiac muscle. The oxygenated side chain in C2 is implicated in the affinity of lepadiformine, which behaved as an amine, for a receptor located near or inside the IK1 pore, and the aliphatic chain length at position C13 is involved in the degree of IK1 blockage. (10.1021/np050215s)
DOI : 10.1021/np050215s
Role of heme iron coordination and protein structure in the dynamics and geminate rebinding of nitric oxide to the H93G myoglobin mutant: Implications for nitric oxide sensors
- Négrerie Michel
- Kruglik Sergei G.
- Lambry Jean-Christophe
- Vos Marten H.
- Martin Jean-Louis
- Franzen S.
Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology , 2006, 281, pp.10389 . The influence of the heme iron coordination on nitric oxide binding dynamics was investigated for the myoglobin mutant H93G (H93G-Mb) by picosecond absorption and resonance Raman time-resolved spectroscopies. In the H93G-Mb, the glycine replacing the proximal histidine does not interact with the heme iron so that exogenous substituents like imidazole may coordinate to the iron at the proximal position. Nitrosylation of H93G-Mb leads to either 6- or 5-coordinate species depending on the imidazole concentration. At high concentrations, (imidazole)-(NO)-6-coordinate heme is formed, and the photoinduced rebinding kinetics reveal two exponential picosecond phases (~10 and ~100 ps) similar to those of wild type myoglobin. At low concentrations, imidazole is displaced by the trans effect leading to a (NO)-5-coordinate heme, becoming 4-coordinate immediately after photolysis as revealed from the transient Raman spectrum. In this case, NO rebinding kinetics remain bi-exponential with no change in time constant of the fast component whose amplitude increases with respect to the 6-coordinate species. Bi-exponential NO geminate rebinding in 5-coordinate H93G-Mb is in contrast with the single-exponential process reported for nitrosylated soluble guanylate cyclase (Negrerie, M., Bouzhir, L., Martin, J. L., and Liebl, U. (2001) J. Biol. Chem. 276, 46815-46821). Thus, our data show that the iron coordination state or the heme iron out-of-plane motion are not at the origin of the bi-exponential kinetics, which depends upon the protein structure, and that the 4-coordinate state favors the fast phase of NO geminate rebinding. Consequently, the heme coordination state together with the energy barriers provided by the protein structure control the dynamics and affinity for NO-binding enzymes. Cop. 2006 by The American Society for Biochemistry and Molecular Biology, Inc. (10.1074/jbc.M513375200)
DOI : 10.1074/jbc.M513375200
Generation and complete characterization of intense mid-infrared ultrashort pulses
- Ventalon Cathie
- Fraser James M.
- Likforman Jean-Pierre
- Villeneuve D. M.
- Corkum Paul B.
- Joffre Manuel
Journal of the Optical Society of America B, Optical Society of America , 2006, 23, pp.332 .
Imaging lipid bodies in cells and tissues using third-harmonic generation microscopy.
- Débarre Delphine
- Supatto Willy
- Pena Ana-Maria
- Fabre Aurelie J
- Tordjmann Thierry
- Combettes Laurent
- Schanne-Klein Marie-Claire
- Beaurepaire Emmanuel
Nature Methods, Nature Publishing Group , 2006, 3 (1), pp.47-53 . Lipid bodies have an important role in energy storage and lipid regulation. Here we show that lipid bodies are a major source of contrast in third-harmonic generation (THG) microscopy of cells and tissues. In hepatocytes, micrometer-sized lipid bodies produce a THG signal 1-2 orders of magnitude larger than other structures, which allows one to image them with high specificity. THG microscopy with approximately 1,200 nm excitation can be used to follow the distribution of lipid bodies in a variety of unstained samples including insect embryos, plant seeds and intact mammalian tissue (liver, lung). We found that epi-THG imaging is possible in weakly absorbing tissues because bulk scattering redirects a substantial fraction of the forward-generated harmonic light toward the objective. Finally, we show that the combination of THG microscopy with two-photon and second-harmonic imaging provides a new tool for exploring the interactions between lipid bodies, extracellular matrix and fluorescent compounds (vitamin A, NADH and others) in tissues. (10.1038/nmeth813)
DOI : 10.1038/nmeth813
Role of Heme Iron Coordination and Protein Structure in the Dynamics and Geminate Rebinding of Nitric Oxide to H93G Myoglobin : Implications for NO-Sensors
- Négrerie Michel
- Kruglik Sergei
- Lambry Jean-Christophe
- Vos Marten H.
- Martin Jean-Louis
- Franzen Stefan
Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology , 2006, 281, pp.10389-10398 .
Role of distal arginine in early sensing intermediates in the heme domain of the oxygen sensor FixL
- Jasaitis Audrius
- Hola Klara
- Bouzhir-Sima Latifa
- Lambry Jean-Christophe
- Balland Véronique
- Vos Marten H.
- Liebl Ursula
Biochemistry, American Chemical Society , 2006, 45, pp.6018-6026 .
Functional implications of the propionate 7 Arginine 220 interaction in the FixLH oxygen sensor from Bradyrhizobium japonicum
- Balland Véronique
- Bouzhir-Sima Latifa
- Anxolabéhère-Mallart E.
- Boussac A.
- Vos Marten H.
- Liebl Ursula
- Mattioli T.
Biochemistry, American Chemical Society , 2006, 45, pp.2072-2084 .
A filtering procedure for systematic removal of pump-perturbed polarization artifacts
- Polack Thomas
Optics Express, Optical Society of America - OSA Publishing , 2006, 14, pp.5823 .
Observer les neurones grâce aux ondes térahertz
- Gallot Guilhem
La Recherche, Sciences et avenir , 2006, 397, pp.26 . Des chercheurs de l'École polytechnique ont développé un dispositif d'imagerie des neurones, fondée sur l'utilisation d'ondes térahertz [1]. Ils observent ainsi les mouvements d'ions et d'eau à l'intérieur et à proximité des neurones.
Terahertz achromatic quarter-wave plate
- Masson Jean-Baptiste
- Gallot Guilhem
Optics Letters, Optical Society of America - OSA Publishing , 2006, 31 (2), pp.265 . Phase retardera usually present a strong frequency dependence. We discuss the design and characterization of a terahertz achromatic quarter-wave plate. This wave plate is made from six birefringent quartz plates precisely designed and stacked together. Phase retardation has been measured over the whole terahertz range by terahertz polarimetry. This achromatic wave plate demonstrates a huge frequency bandwidth (?max/?min ˜ 7), and therefore can be applied to terahertz time domain spectroscopy and polarimetry. Cop. 2006 Optical Society of America. (10.1364/OL.31.000265)
DOI : 10.1364/OL.31.000265
Evaluation of 23S rRNA PCR primers for use in phylogenetic studies of bacterial diversity
- Hunt D.E.
- Klepac-Ceraj V.
- Acinas S.G.
- Bertilsson S.
- Gautier Christian
- Polz M.F.
Applied and Environmental Microbiology, American Society for Microbiology , 2006, 72 (3), pp.2221 . The availability of a diverse set of 23S rRNA gene sequences enabled evaluation of the specificity of 39 previously published and 4 newly designed primers specific for bacteria. An extensive clone library constructed using an optimized primer pair resulted in similar gene richness but slightly differing coverage of some phylogenetic groups, compared to a 16S rRNA gene library from the same environmental sample. Copyright Cop. 2006, American Society for Microbiology. All Rights Reserved. (10.1128/AEM.72.3.2221-2225.2006)
DOI : 10.1128/AEM.72.3.2221-2225.2006
Chiroptical effects in the second harmonic generation from collagens I and IV: applications in nonlinear microscopy
- Pena Ana-Maria
- Boulesteix Thierry
- Dartigalongue Thibault
- Strupler Mathias
- Beaurepaire Emmanuel
- Schanne-Klein Marie-Claire
Nonlinear optics, quantum optics, Old City Pub. , 2006, 35 (1-3), pp.235-240 . An emerging application of multiphoton microscopy is the observation of unstained intact biological tissues based on intrinsic sources of nonlinear signals. However, reliable biomedical imaging requires a thorough analysis of these endogenous signals. Looking at skin biopsies, we focused on 2-Photon Excited Fluorescence (2PEF) arising from cytokeratins in the epidermis, and second harmonic generation (SHG) from collagen fibers in the dermis. We determined the 2PEF excitation spectrum and action cross section of purified keratins from human epidermis, and obtained a good agreement with in situ measurements. In order to analyze the role of chirality and collagen type in SHG signal, we performed polarization-resolved surface SHG experiments on thin films of collagens I and IV molecules. We observed that collagen I and IV molecules exhibit comparable SHG signals, except for the chiral contributions which are absent for collagen IV and represent typically 50% of the signal for collagen I. We concluded that the large collagen I SHG efficiency is dominated by coherent effects due to the high density and quasi-crystalline order in collagen fibrils, whereas the lack of any alignment within the collagen IV molecules explains the absence of signal from this collagen type in SHG microscopy.
Micrometer scale ex vivo multiphoton imaging of unstained arterial wall structure
- Boulesteix Thierry
- Pena Ana-Maria
- Pagès Nicole
- Godeau G.
- Sauviat Martin-Pierre
- Beaurepaire Emmanuel
- Schanne-Klein Marie-Claire
Cytometry Part A, Wiley , 2006, 69A (1), pp.20-26 . We characterize the application of multiphoton microscopy to the observation of the extracellular matrix of fresh unstained vessels. Combined two-photon-excited fluorescence (2PEF) and second harmonic generation (SHG) imaging of large arteries reveals the architecture of elastin and collagen fibers in the vessel wall with remarkable specificity. We present elastin/collagen imaging in unstained rat vessels at both micrometer and whole vessel scales, and we characterize the optical properties of rat carotid artery and aorta walls. We apply this method to evidence deleterious effects of residual doses of a pesticide on the vessel wall. This study illustrates the potential of 2PEF/SHG microscopy for pharmacological studies in unlabeled arteries. © 2005 Wiley-Liss, Inc. (10.1002/cyto.a.20196)
DOI : 10.1002/cyto.a.20196
Glu-Q-tRNAAsp synthetase coded by the yadB gene, a new paralog of aminoacyl-tRNA synthetase that glutamylates tRNAAsp anticodon
- Blaise Mickaël
- Becker Hubert F.
- Lapointe Jacques
- Cambillau Christian
- Giegé Richard
- Kern Daniel
Biochimie, Elsevier , 2005, 87 (9-10), pp.847-861 . Analysis of the completed genome sequences revealed presence in various bacteria of an open reading frame (ORF) encoding a polypeptide chain presenting important similarities with the catalytic domain of glutamyl-tRNA synthetases but deprived of the C-terminal anticodon-binding domain. This paralog of glutamyl-tRNA synthetases, the YadB protein, activates glutamate in the absence of tRNA and transfers the activated glutamate not on tRNA(Glu) but instead on tRNA(Asp). It has been shown that tRNA(Asp) is able to accept two amino acids: aspartate charged by aspartyl-tRNA synthetase and glutamate charged by YadB. The functional properties of YadB contrast with those of the canonical glutamyl-tRNA synthetases, which activate Glu only in presence of the cognate tRNA before aminoacylation of the 3'-end of tRNA. Biochemical approaches and mass spectrometry investigations revealed that YadB transfers the activated glutamate on the cyclopenthene-diol ring of the modified nucleoside queuosine posttranscriptionally inserted at the wobble position of the anticodon-loop to form glutamyl-queuosine. Unstability of the ester bond between the glutamate residue and the cyclopenthene-diol (half-life 7.5 min) explains why until now this modification escaped detection. Among Escherichia coli tRNAs containing queuosine in the wobble position, only tRNA(Asp) is substrate of YadB. Sequence comparison reveals a structural mimicry between the anticodon-stem and loop of tRNA(Asp) and the amino acid acceptor-stem of tRNA(Glu). YadB, renamed glutamyl-Q-tRNA(Asp) synthetase, constitutes the first enzyme structurally related to aminoacyl-tRNA synthetases which catalyzes a hypermodification in tRNA, and whose function seems to be conserved among prokaryotes. The discovery of glutamyl-Q-tRNA(Asp) synthetase breaks down the current paradigm according to which the catalytic domain of aminoacyl-tRNA synthetases recognizes the amino acid acceptor-stem of tRNA and aminoacylates the 3'-terminal ribose. The evolutionary significance of the existence of an aminoacyl-tRNA synthetase paralog dedicated to the hypermodification of a tRNA anticodon will be discussed. (10.1016/j.biochi.2005.03.007)
DOI : 10.1016/j.biochi.2005.03.007
Structure sensitivity in third-harmonic generation microscopy
- Débarre Delphine
- Supatto Willy
- Beaurepaire Emmanuel
Optics Letters, Optical Society of America - OSA Publishing , 2005, 30, pp.2134-2136 . We characterize experimentally the influence of sample structure and beam focusing on signal level in third-harmonic generation (THG) microscopy. In the case of a homogeneous spherical sample, the dependence of the signal on the size of the sphere can be controlled by modifying the Rayleigh length of the excitation beam. More generally, the influence of excitation focusing on the signal depends on sample geometry, allowing one to highlight certain structures within a complex system. We illustrate this point by focusing-based contrast modulation in THG images of Drosophila embryos. (10.1364/OL.30.002134)
DOI : 10.1364/OL.30.002134
Role of arginine 220 in the oxygen sensor FixL from Bradyrhizobium japonicum
- Balland Véronique
- Bouzhir-Sima Latifa
- Kiger Laurent
- Marden Michael C.
- Vos Marten H.
- Liebl Ursula
- Mattioli Tony A.
Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology , 2005, 280, pp.15279-15288 . In the heme-based oxygen sensor protein FixL, conformational changes induced by oxygen binding to the heme sensor domain regulate the activity of a neighboring histidine kinase, eventually restricting expression of specific genes to hypoxic conditions. The conserved arginine 220 residue is suggested to play a key role in the signal transduction mechanism. To obtain detailed insights into the role of this residue, we replaced Arg220 by histidine (R220H), glutamine (R220Q), glutamate (R220E), and isoleucine (R220I) in the heme domain FixLH from Bradyrhizobium japonicum. These mutations resulted in dramatic changes in the O2 affinity with Kd values in the order R220I < R220Q < wild type < R220H. For the R220H and R220Q mutants, residue 220 interacts with the bound O2 or CO ligands, as seen by resonance Raman spectroscopy. For the oxy-adducts, this H-bond modifies the π acidity of the O2 ligand, and its strength is correlated with the back-bonding-sensitive ν4 frequency, the koff value for O2 dissociation, and heme core-size conformational changes. This effect is especially strong for the wild-type protein where Arg220 is, in addition, positively charged. These observations strongly suggest that neither strong ligand fixation nor the displacement of residue 220 into the heme distal pocket are solely responsible for the reported heme conformational changes associated with kinase activity regulation, but that a significant decrease of the heme π* electron density because of strong back-bonding toward the oxygen ligand also plays a key role. (10.1074/jbc.M413928200)
DOI : 10.1074/jbc.M413928200
Functionality of nitrated acetylcholine receptor: The two-step formation of nitrotyrosines reveals their differential role in effectors binding
- Négrerie Michel
- Martin Jean-Louis
- Nghiêm H.-O.
FEBS Letters, Wiley , 2005, 579 (12), pp.2643 . The presence of nitrotyrosines is associated with several neurodegenerative pathologies. We evaluated the functionality of the nicotinic acetylcholine receptor possessing nitrotyrosines. The spectrum of the nitrated receptor displays an absorption band characteristic of ortho-nitrophenol. The presence of carbamylcholine in the agonist site prevented the effect of nitration by tetranitromethane in some conditions. The nitration occurred with two discrete steps and pointed out the differential involvement of tyrosines in the binding of acetylcholine and neurotoxin. We concluded that at least two residues involved in agonist binding can be nitrated, which bring similar contributions to the binding energy of the neurotransmitter. Cop. 2005 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved. (10.1016/j.febslet.2005.03.084)
DOI : 10.1016/j.febslet.2005.03.084
Mid-infrared electric field characterization using a visible charge-coupled-device-based spectrometer
- Kubarych Kevin J.
- Joffre Manuel
- Moore Amy
- Belabas Nadia
- Jonas David
Optics Letters, Optical Society of America - OSA Publishing , 2005, 30 (10), pp.1228-1230 . We characterize ultrashort mid-infrared pulses through upconversion by using the stretched pulses obtained from the uncompressed output of a chirped-pulse amplifier. The power spectrum thus translated into the visible region can be readily measured with a standard silicon CCD camera-based spectrometer. The spectral phase is also characterized by a variant of zero-added-phase spectral phase interferometry for direct electric field reconstruction. This is a general method that provides a multiplex advantage over conventional infrared detector array-based methods. © 2005 Optical Society of America (10.1364/OL.30.001228)
DOI : 10.1364/OL.30.001228
Spectroscopic analysis of keratin endogenous signal for skin multiphoton microscopy: erratum
- Pena Ana-Maria
- Strupler Mathias
- Boulesteix Thierry
- Godeau G.
- Schanne-Klein Marie-Claire
Optics Express, Optical Society of America - OSA Publishing , 2005, 13 (17), pp.6667 . We present corrected versions of the list of authors and of Section 2.1. (10.1364/OPEX.13.006667)
DOI : 10.1364/OPEX.13.006667
Activationless electron transfer through the hydrophobic core of cytochrome c oxidase
- Jasaitis Audrius
- Rappaport F.
- Pilet Eric
- Liebl Ursula
- Vos Marten H.
Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences , 2005, 102 (31), pp.10882 . Electron transfer (ET) within proteins occurs by means of chains of redox intermediates that favor directional and efficient electron delivery to an acceptor. Individual ET steps are energetically characterized by the electronic coupling V, driving force ΔG, and reorganization energy λ. λ reflects the nuclear rearrangement of the redox partners and their environment associated with the reactions; λ ≈ 700-1,100 meV (1 eV = 1.602 × 10-19 J) has been considered as a typical value for intraprotein ET. In nonphotosynthetic systems, functional ET is difficult to assess directly. However, using femtosecond flash photolysis of the CO-poised membrane protein cytochrome c oxidase, the intrinsic rate constant of the low-ΔG electron injection from heme a into the heme a 3-CuB active site was recently established at (1.4 ns)-1. Here, we determine the temperature dependence of both the rate constant and ΔG of this reaction and establish that this reaction is activationless. Using a quantum mechanical form of nonadiabatic ET theory and common assumptions for the coupled vibrational modes, we deduce that λ is <200 meV. It is demonstrated that the previously accepted value of 760 meV actually originates from the temperature dependence of CuB-CO bond breaking. We discuss that low-ΔG, low-λ reactions are common for efficiently channeling electrons through chains that are buried inside membrane proteins. (10.1073/pnas.0503001102)
DOI : 10.1073/pnas.0503001102
Nonlinear optical spectroscopy of chiral molecules
- Fischer Peer
- Hache François
Chirality, Wiley , 2005, 17 (8), pp.421 . We review nonlinear optical processes that are specific to chiral molecules in solution and on surfaces. In contrast to conventional natural optical activity phenomena, which depend linearly on the electric field strength of the optical field, we discuss how optical processes that are nonlinear (quadratic, cubic, and quartic) functions of the electromagnetic field strength may probe optically active centers and chiral vibrations. We show that nonlinear techniques open entirely new ways of exploring chirality in chemical and biological systems: The cubic processes give rise to nonlinear circular dichroism and nonlinear optical rotation and make it possible to observe dynamic chiral processes at ultrafast time scales. The quadratic second-harmonic and sum-frequency-generation phenomena and the quartic processes may arise entirely in the electric-dipole approximation and do not require the use of circularly polarized light to detect chirality. They provide surface selectivity and their observables can be relatively much larger than in linear optical activity. These processes also give rise to the generation of light at a new color, and in liquids this frequency conversion only occurs if the solution is optically active. We survey recent chiral nonlinear optical experiments and give examples of their application to problems of biophysical interest. Cop. 2005 Wiley-Liss, Inc. (10.1002/chir.20179)
DOI : 10.1002/chir.20179
Téléphonie cellulaire et cancer: où en est-on? [Cellular phones and cancer: Current status]
- Colonna Anne
Bulletin du Cancer, Elsevier , 2005, 92 (7), pp.637 . L'évaluation de l'impact des nouvelles technologies sur le corps humain est indispensable pour imposer les normes réglementaires limitant les risques sanitaires. L'apparition et l'évolution des téléphones cellulaires ont été parmi les plus rapides dans l'histoire des innovations. De nombreuses recherches ont été effectuées pour tenter d'évaluer le lien éventuel entre effet sur la santé et téléphonie mobile, au niveau du téléphone cellulaire mais également des stations de base. Cet article présente un aperçu des connaissances en matière de recherche sur l'incidence des ondes radiofréquences. Études épidémiologiques, cellulaires et animales se succèdent mais aucune conclusion définitive n'a pu être établie. Même si certains effets biologiques sur des cellules en culture ont été observés, le lien avec un possible développement de cancer chez l'homme reste encore loin d'être établi. Les études animales montrent pour la plupart des résultats négatifs. Quant aux études épidémiologiques, elles manquent d'un recul suffisant pour pouvoir évaluer l'effet des technologies utilisées aujourd'hui. Face à l'inquiétude des populations, opérateurs de téléphonie mobile, constructeurs et instances gouvernementales financent nombre de projets scientifiques afin de permettre une réglementation adaptée et efficace. [Evaluation of the impact of new technologies on the human body is essential in order to impose regulations to limit health risks. The appearance and evolution of cellular phones have been one of the fastest in the history of innovation. Research reported worldwide has tried to evaluate any potential link between adverse health effects and the mobile phone and its broadcasting stations. This article gives an overview of current research knowledge on the impact of radiofrequency waves on health. Epidemiologic, cellular and animal studies have been carried out, but none of them have reached definitive conclusions. Although some biological effects on cell culture have been observed, their link with human cancer development is far from established. Most of the animal studies show negative results. Epidemiologic studies lack a sufficient perspective to be able to evaluate the effect of evolving technologies used today. High levels of concern by the public have urged mobile phone operators, manufacturers and governmental authorities to finance a number of scientific projects aimed at defining adapted and effective regulations.] Cop. John Libbey Eurotext.
Classical calculation of myoglobin circular dichroism spectrum: simulation of a time-resolved experiment
- Dartigalongue Thibault
- Hache François
The Journal of Chemical Physics, American Institute of Physics , 2005, 123, pp.184901 .
La ciguatera : de l'étiologie du phénomène au traitement de ses symptômes. [Ciguatera: from the etiology of the phenomenon to the treatment of its symptoms]
- Boydron-Le Garrec Raphaële
- Benoit Evelyne
- Sauviat Martin-Pierre
- Frostin Maryvonne
- Laurent Dominique
Journal de la Société de Biologie , 2005, 199(2), pp.127-139 . Ciguatera is the most common food poisoning found in the tropical and subtropical areas, acquired by the consumption of marine products. A lot of work concerning its etiology, its epidemiology and its clinical effects, as well as the discovery of the toxins involved, the description of their transfer, the study of their structure and the analysis of their pharmacological effects, have allowed a better understanding of the ciguateric phenomenon. Ciguatera is known to be due to benthic dinoflagellates belonging to the Gambierdiscus gender, in particular G. toxicus. Under specific conditions, this microalga produces gambier-toxins, toxins which are the precursors of other toxins, the ciguatoxins. However, the factors supporting this production are still poorly known, and the implication of others dinoflagellates, cyanophytes or bacteria have been suspected. In contrast, the fish species responsible for the transmission of ciguatera are globally well identified. The clinical symptoms of the intoxication are now well described. They mainly include digestive, neurological and cardiovascular disorders whose preponderance varies according to the nature of the toxins involved, since toxin structures are different between one ocean and the other. The ciguateric intoxication tends to be exported towards non endemic areas where it is still misdiagnosed. No specific antidote exists to date, and it is only by symptomatic or palliative treatments that ciguatera is currently treated.
Détection des ciguatoxines: avantages et inconvénients des différentes méthodes biologiques utilisées [Detection of ciguatoxins: advantages and drawbacks of different biological methods]
- Boydron-Le Garrec Raphaële
- Benoit Evelyne
- Sauviat Martin-Pierre
- Laurent Dominique
Journal de la Société de Biologie , 2005, 199 (2), pp.115-125 . La ciguatera est une intoxication consécutive à la consommation de poissons des récifs contaminés par des toxines spécifiques, les ciguatoxines, à des niveaux capables d'engendrer chez l'Homme une toxicité par voie orale. Les précurseurs de ces toxines sont les gambiertoxines, produites par des Dinoflagellés du genre Gambierdiscus. Ces toxines sont accumulées dans le foie et la chair des poissons brouteurs, herbivores et carnivores, et biotransformées en ciguatoxines plus nocives pour l'Homme. En l'absence de traitement spécifique, la ciguatera reste un problème non seulement de santé publique, mais également socio-économique. La détection des ciguatoxines, au sein des poissons ou de leurs extraits, est donc primordiale et recherchée depuis longtemps. De nombreuses méthodes, biologiques, chimiques ou immunochimiques, ont été développées dans ce but. Cette revue est plus particulièrement centrée sur les méthodes biologiques, développées in vivo ou in vitro, depuis le test de toxicité aiguë sur Souris, maintenant parfaitement standardisé, jusqu'aux méthodes les plus récentes telles que le test de fixation spécifique sur synaptosomes de Rat. Outre la Souris, le Poulet et la Mangouste ont été encore récemment utilisés, notamment pour des tests préliminaires avant l'extraction des ciguatoxines à partir des poissons. Au contraire, diverses autres méthodes in vivo, telles que celles pratiquées sur le Chat, les Culicidés ou les larves de Diptères, furent abandonnées malgré leurs résultats intéressants. Finalement, bien qu'excluant une détection des ciguatoxines sur le terrain, les tests sur neuroblastomes de Souris et synaptosomes de Rat, nouvelles méthodes réalisées in vitro, ont permis un gain considérable tant en sensibilité qu'en spécificité pour détecter les ciguatoxines.