Waterborne Signaling Primes the Expression of Elicitor-Induced Genes and Buffers the Oxidative Responses in the Brown Alga Laminaria digitata

As marine sessile organisms, seaweeds must respond efficiently to biotic and abiotic challenges in their natural environment to reduce the fitness consequences of wounds and oxidative stress. This study explores the early steps of the defense responses of a large marine brown alga (the tangle kelp Laminaria digitata) and investigates its ability to transmit a warning message to neighboring conspecifics. We compared the early responses to elicitation with oligoguluronates in laboratory-grown and harvested wild individuals of L. digitata. We followed the release of H2O2 and the concomitant production of volatile organic compounds. We also monitored the kinetics of expression of defense-related genes following the oxidative burst. Laboratory-grown algae were transplanted in kelp habitats to further evaluate their responses to elicitation after a transient immersion in natural seawater. In addition, a novel conditioning procedure was established to mimic field conditions in the laboratory. Our experiments showed that L. digitata integrates waterborne cues present in the kelp bed and/or released from elicited neighboring plants. Indeed, the exposure to elicited conspecifics changes the patterns of oxidative burst and volatile emissions and potentiates this kelp for faster induction of genes specifically regulated in response to oligoguluronates. Thus, waterborne signals shape the elicitor-induced responses of kelps through a yet unknown mechanism reminiscent of priming in land plants

Aryl hydrocarbon receptor-dependent upregulation of Cyp1b1 by TCDD and diesel exhaust particles in rat brain microvessels

<p>Abstract</p> <p>Background</p> <p>AhR activates the transcription of several target genes including CYP1B1. Recently, we showed <it>CYP1B1 </it>as the major cytochrome P450 (CYP) enzyme expressed in human brain microvessels. Here, we studied the effect of AhR activation by environmental pollutants on the expression of Cyp1b1 in rat brain microvessels.</p> <p>Methods</p> <p>Expression of AhR and Cyp1b1 was detected in isolated rat brain microvessels. AhR was immunovisualised in brain microvessel endothelial cells. The effect of AhR ligands on Cyp1b1 expression was studied using isolated brain microvessels after <it>ex vivo </it>and/or <it>in vivo </it>exposure to TCDD, heavy hydrocarbons containing diesel exhaust particles (DEP) or Δ⁹-tetrahydrocannabinol (Δ⁹-THC).</p> <p>Results</p> <p>After <it>ex vivo </it>exposure to TCDD (a highly potent AhR ligand) for 3 h, <it>Cyp1b1 </it>expression was significantly increased by 2.3-fold in brain microvessels. A single i.p. dose of TCDD also increased <it>Cyp1b1 </it>transcripts (22-fold) and Cyp1b1 protein (2-fold) in rat brain microvessels at 72 h after TCDD. Likewise, DEP treatment (<it>in vivo </it>and <it>ex vivo</it>) strongly induced Cyp1b1 protein in brain microvessels. DEP-mediated Cyp1b1 induction was inhibited by actinomycin D, cycloheximide, or by an AhR antagonist. In contrast, a sub-chronic <it>in vivo </it>treatment with Δ⁹-THC once daily for 7 seven days had no effect on <it>Cyp1b1 </it>expression</p> <p>Conclusions</p> <p>Our results show that TCDD and DEP strongly induced Cyp1b1 in rat brain microvessels, likely through AhR activation.</p

Mass Spectrometry-Based Metabolomics to Elucidate Functions in Marine Organisms and Ecosystems

Marine systems are very diverse and recognized as being sources of a wide range of biomolecules. This review provides an overview of metabolite profiling based on mass spectrometry (MS) approaches in marine organisms and their environments, focusing on recent advances in the field. We also point out some of the technical challenges that need to be overcome in order to increase applications of metabolomics in marine systems, including extraction of chemical compounds from different matrices and data management. Metabolites being important links between genotype and phenotype, we describe added value provided by integration of data from metabolite profiling with other layers of omics, as well as their importance for the development of systems biology approaches in marine systems to study several biological processes, and to analyze interactions between organisms within communities. The growing importance of MS-based metabolomics in chemical ecology studies in marine ecosystems is also illustrated

Voies de signalisation apoptotique induites par le trioxyde d'arsenic dans des cellules de leucémie myéloïde chronique

Les cellules Leucémie Myéloïde Chronique (LMC) sont résistantes à la quasi-totalité des agents anticancéreux, du fait de la présence de l oncoprotéine BCR-ABL au pouvoir anti-apoptotique très ubiquitaire, mais restent sensibles à l apoptose induite par le trioxyde d arsenic (As2O3). Une étude multicentrique associant le trioxyde d arsenic (Trisenox®) et l imatinib mesylate (Glivec®) dans l indication des LMC résistantes au Glivec® utilisé en monothérapie est en cours. Notre travail consiste à identifier les voies de signalisation apoptotique initiées par l As2O3 et à comprendre leur spécificité dans leur insensibilité à la signalisation de BCR-ABL. Nous avons montré que l As2O3 induit l apoptose par une voie apoptotique débutant à la mitochondrie et une activation atypique de JNK, dépendante de la voie Rho-ROCK, impliquée dans l apoptose. La petite GTPase Rho serait donc à l apex de cette cascade de signalisation apoptotique. Par ailleurs, cette voie Rho-ROCK-JNK est indépendante de la signalisation de BCR-ABL et ce mode d activation inhabituel de JNK pourrait donc expliquer, du moins en partie, l efficacité de l As2O3 dans les cellules de LMC.Arsenic trioxide (As2O3) a potent drug in the treatment of acute promyelocytic leukemia (APL), is now investigated, in conjunction with imatinib mesylate, in chronic myeloid leukemia (CML) patients resistant to initial imatinib treatment. Mechanisms of As2O3 induced cell death have primarily been studied in APL cells. We therefore investigated the apoptotic signaling activated by As2O3 in the model CML cell line K562. As2O3 was found to induce apoptosis in these cells via the intrinsic pathway, dependent on initial mitochondrial events. As2O3 also induces a sustained JNK activation which precedes and is necessary for caspase-9 activation as well as apoptosis induction. JNK is known to be primarily activated by cellular stress but recent data have uncovered another pathway involving the small GTPase Rho. We established that Rho and its effector, the kinase ROCK, are activated by As2O3. Inhibition of either Rho or ROCK prevented JNK activation and protected against apoptosis. Thus, in CML cells, apoptosis induced by As2O3 is mediated, at least in part, via a Rho-ROCK-JNK axis. These findings define a novel signaling pathway for As2O3.CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Traçabilité manuelle des dispositifs médicaux sur trois sites de stérilisation de l'hôpital Necker-enfants malades (étude et amélioration de la qualité)

CHATENAY M.-PARIS 11-BU Pharma. (920192101) / SudocSudocFranceF

Identification et dosage de dérivés oxydés d'acides gras polyinsaturés dans les milieux biologiques par une approche métabolomique ciblée

Les oxylipides/oxylipines, dérivés oxydés d'acides gras polyinsaturés, jouent un rôle important dans la signalisation lipidique, en réponse à un stress biotique ou abiotique, chez les animaux comme chez les végétaux. Nous avons mis au point des méthodes spécifiques de dosage des oxylipides dans des échantillons biologiques d'origine humaine et phycologique (algues). Ces méthodes font appel à la spectrométrie de masse couplée à la chromatographie en phase gazeuse ou liquide (GC/MS/NCI et LC/MS). Ainsi, nous avons : -établi une méthode de dosage des EETs dans le sang humain par GC/MS/NCI. Ces métabolites époxydés de l'acide arachidonique (AA) par les cytochromes P450 ont des propriétés de vasorelaxation. -mis en évidence la production de 20-HETE, métabolite de l'AA, par le CYFP dans une lignée hépatomateuse humaine, HepaRG. -étudié la formation des énantiomères du 19,20-époxyde de l'acide docosahaénoïque (DHA) après incubation de cytochromes P450 recombinants humains avec du [14C]-DHA, ainsi que leur séparation sur colonne chirale. -identifié une signature oxylipidique de la réponse de l'algue brune Laminaria digitata au stress induit par le cuivre, révélant des voies de synthèse enzymatique et chimique ainsi qu'un nouveau composé : l'acide 18-hydroxy, 17-oxo-eicosatétranoïque. -mis en évidence l'émission d'aldéhydes polyinsaturés par les algues en réponse à un stress. Ces composés sont impliqués dans la communication interplante menant à une potentialisation des défenses face au stress biotique mimé par les oligoguluronates. Ces résultats devraient contribuer à une meilleure compréhension du rôle des oxylipides chez l'homme comme chez l'algue.Oxylipids/oxylipins, oxidized derivatives of polyunsaturated fatty acids, play a major role in lipid signalization, during biotic or abiotic stress, in both mammals ans in higher plants. We established specific methods for quantifying oxylipids in biological samples of human or phycologic (algae) origin. These methods are based on mass spectrometry coupled with gas or liquid chromatography (GC/MS/NCI and LC/MS). Thus, we have : -established a quantification method of EETs from human blood by GC/MS/NCI. These arachidonic acid (AA) metabolites by the action of cytochromes P450, have vasorelaxation properties. -highlighted the specific production of 20-HETE, an AA metabolite, by the CYP4F3B in a human hepatoma cell line, HepaRG. -studied the formation of docosahexaenoic acid (DHA) 19,20-epoxide enantiomers after incubation of recombinant human cytochromes P450 with [14C]-DHA and their separation on a chiral column. -identified an oxylipin signature of the response of the brown marine alga Laminaria digitata during abiotic stress, induced by copper, revealing enzymatic and chemical synthesis pathways. The presence of a new compound, the 18-hydroxy, 17-oxo-eicosatetraenoic acid has been described. -highlighted the polyinsaturated aldehyde emission in response to stress in this alga. These compounds are involved in distance signaling and inter-plant communication leading to a priming of defenses during a biotic stress mimicked by oligoguluronates. These results could allow a better comprehension of the oxylipid role in man as algae.BREST-BU Médecine-Odontologie (290192102) / SudocSudocFranceF

A case report of photodermatoses induced by the antifungal drug terbinafine

International audienc

Constitutive or Inducible Protective Mechanisms against UV-B Radiation in the Brown Alga Fucus vesiculosus? A Study of Gene Expression and Phlorotannin Content Responses.

A role as UV sunscreens has been suggested for phlorotannins, the phenolic compounds that accumulate in brown algae in response to a number of external stimuli and take part in cell wall structure. After exposure of the intertidal brown alga Fucus vesiculosus to artificial UV-B radiation, we examined its physiological responses by following the transcript level of the pksIII gene encoding a phloroglucinol synthase, likely to be involved in the first step of phlorotannins biosynthesis. We also monitored the expression of three targeted genes, encoding a heat shock protein (hsp70), which is involved in global stress responses, an aryl sulfotransferase (ast), which could be involved in the sulfation of phlorotannins, and a vanadium bromoperoxidase (vbpo), which can potentially participate in the scavenging of Reactive Oxygen Species (ROS) and in the cross-linking and condensation of phlorotannins. We investigated whether transcriptional regulation of these genes is correlated with an induction of phlorotannin accumulation by establishing metabolite profiling of purified fractions of low molecular weight phlorotannins. Our findings demonstrated that a high dose of UV-B radiation induced a significant overexpression of hsp70 after 12 and 24 hours following the exposure to the UV-B treatment, compared to control treatment. The physiological performance of algae quantified by the photosynthetic efficiency (Fv/Fm) was slightly reduced. However UV-B treatment did not induce the accumulation of soluble phlorotannins in F. vesiculosus during the kinetics of four weeks, a result that may be related to the lack of induction of the pksIII gene expression. Taken together these results suggest a constitutive accumulation of phlorotannins occurring during the development of F.vesiculosus, rather than inducible processes. Gene expression studies and phlorotannin profiling provide here complementary approaches to global quantifications currently used in studies of phenolic compounds in brown algae

La possibilité d’une sociologie narrative

Nous voilà attablés à dix mains sur clavier pour écrire ce que rend possible notre écart à la discipline sociologique, une même envie de bouger quelque chose dans l’étau des spécialités académiques, un « vouloir savoir » autrement que nous partageons sur notre site web avec un accent grave pour entrer dans la matière du social, de la vie quotidienne, de la vie ordinaire. D’abord le récit tiré d’une longue enquête suivi d’une courte observation pour illustrer deux modalités de cet « Écouter – Voir » qui nous autorise à passer du « nous » au « je » sans mal dire, le « je » de l’observation directe dans la narration, et le « nous » dans l’action où l’échelle est plus éloignée. Viendra ensuite dans une seconde partie une discussion sur le rapport entre la littérature et la sociologie lorsqu’il s’agit d’ouvrir les yeux sur la pauvreté et le chômage. Pour élargir « les vues », nous avons besoin d’accroître les mots et le langage. Il s’agira enfin dans une troisième partie de pointer les textes qui interrogent les sciences sociales en se tenant à la périphérie de la littérature sans céder à la sanctification de l’œuvre