Microarray Analysis in the Archaeon Halobacterium salinarum Strain R1

Background: Phototrophy of the extremely halophilic archaeon Halobacterium salinarum was explored for decades. The research was mainly focused on the expression of bacteriorhodopsin and its functional properties. In contrast, less is known about genome wide transcriptional changes and their impact on the physiological adaptation to phototrophy. The tool of choice to record transcriptional profiles is the DNA microarray technique. However, the technique is still rarely used for transcriptome analysis in archaea. Methodology/Principal Findings: We developed a whole-genome DNA microarray based on our sequence data of the Hbt. salinarum strain R1 genome. The potential of our tool is exemplified by the comparison of cells growing under aerobic and phototrophic conditions, respectively. We processed the raw fluorescence data by several stringent filtering steps and a subsequent MAANOVA analysis. The study revealed a lot of transcriptional differences between the two cell states. We found that the transcriptional changes were relatively weak, though significant. Finally, the DNA microarray data were independently verified by a real-time PCR analysis. Conclusion/Significance: This is the first DNA microarray analysis of Hbt. salinarum cells that were actually grown under phototrophic conditions. By comparing the transcriptomics data with current knowledge we could show that our DNA microarray tool is well applicable for transcriptome analysis in the extremely halophilic archaeon Hbt. salinarum. The reliability of our tool is based on both the high-quality array of DNA probes and the stringent data handling including MAANOVA analysis. Among the regulated genes more than 50% had unknown functions. This underlines the fact that haloarchaeal phototrophy is still far away from being completely understood. Hence, the data recorded in this study will be subject to future systems biology analysis

Selective intra-carotid blood cooling in acute ischemic stroke : a safety and feasibility study in an ovine stroke model

Selective therapeutic hypothermia (TH) showed promising preclinical results as a neuroprotective strategy in acute ischemic stroke. We aimed to assess safety and feasibility of an intracarotid cooling catheter conceived for fast and selective brain cooling during endovascular thrombectomy in an ovine stroke model. Transient middle cerebral artery occlusion (MCAO, 3 h) was performed in 20 sheep. In the hypothermia group (n = 10), selective TH was initiated 20 minutes before recanalization, and was maintained for another 3 h. In the normothermia control group (n = 10), a standard 8 French catheter was used instead. Primary endpoints were intranasal cooling performance (feasibility) plus vessel patency assessed by digital subtraction angiography and carotid artery wall integrity (histopathology, both safety). Secondary endpoints were neurological outcome and infarct volumes. Computed tomography perfusion demonstrated MCA territory hypoperfusion during MCAO in both groups. Intranasal temperature decreased by 1.1 °C/3.1 °C after 10/60 minutes in the TH group and 0.3 °C/0.4 °C in the normothermia group (p < 0.001). Carotid artery and branching vessel patency as well as carotid wall integrity was indifferent between groups. Infarct volumes (p = 0.74) and neurological outcome (p = 0.82) were similar in both groups. Selective TH was feasible and safe. However, a larger number of subjects might be required to demonstrate efficacy

RNAi-mediated suppression of isoprene emission in poplar transiently impacts phenolic metabolism under high temperature and high light intensities: a transcriptomic and metabolomic analysis

In plants, isoprene plays a dual role: (a) as thermo-protective agent proposed to prevent degradation of enzymes/membrane structures involved in photosynthesis, and (b) as reactive molecule reducing abiotic oxidative stress. The present work addresses the question whether suppression of isoprene emission interferes with genome wide transcription rates and metabolite fluxes in grey poplar (Populusxcanescens) throughout the growing season. Gene expression and metabolite profiles of isoprene emitting wild type plants and RNAi-mediated non-isoprene emitting poplars were compared by using poplar Affymetrix microarrays and non-targeted FT-ICR-MS (Fourier transform ion cyclotron resonance mass spectrometry). We observed a transcriptional down-regulation of genes encoding enzymes of phenylpropanoid regulatory and biosynthetic pathways, as well as distinct metabolic down-regulation of condensed tannins and anthocyanins, in non-isoprene emitting genotypes during July, when high temperature and light intensities possibly caused transient drought stress, as indicated by stomatal closure. Under these conditions leaves of non-isoprene emitting plants accumulated hydrogen peroxide (H2O2), a signaling molecule in stress response and negative regulator of anthocyanin biosynthesis. The absence of isoprene emission under high temperature and light stress resulted transiently in a new chemo(pheno)type with suppressed production of phenolic compounds. This may compromise inducible defenses and may render non-isoprene emitting poplars more susceptible to environmental stress

Rapid regulation of the methylerythritol 4-phosphate pathway during isoprene synthesis

More volatile organic carbon is lost from plants as isoprene than any other molecule. This flux of carbon to the atmosphere affects atmospheric chemistry and can serve as a substrate for ozone production in polluted air. Isoprene synthesis may help lea

Contribution à l'étude de la dynamique du thon rouge atlantique (Approches écologiques et océanographiques )

L'analyse des données spatio-temporelles est appliquée à l'étude de la dynamique du thon rouge, Thunnus thynnus. Les échelles locales, régionales et globales sont considérées successivement dans trois volets différents. L'approche phénoménologique, basée sur la reconnaissance de formes, le filtrage, le lissage et la théorie de l'estimation en général est une caractéristique de ce travail, on y présente les possibilités offertes par ces techniques en écologie marine, et en particulier le besoin d une décomposition fréquentielle des processus biogéophysiques. Quelques modalités du test d'hypothèse sont discutées ainsi que le problème de la significativité des résultats en séries temporelles ou dans l'analyse de processus spécialisés. Le premier volet porte sur l'hétérogénéité spatiale locale de l'habitat pélagique et des effets des fonts océaniques sur la structuration. On y présente illustrés d'un premie exemple, les problèmes de détection et de cartographique des fronts. On aborde ensuite les modalités d'étude des relations fronts/prédateurs pélagiques. Un deuxième exemple basé sur les campagnes de survol STROMBOLI dans le golfe du lion et des données de radiométrie haute résolutin vient illustrer cette partie. On y montre en particulier le besoin de métohdes dédiées (e.g. Monte-Carlo) pour assurer les tests de significativité. Le deuxième volet aborde l'étude de l'habitat pélagique par l'intermédiaire des marques archives. Trois obstacles majeurs sont identifiés (i) les larges erreurs de géolocalisation associées à cette technologie (ii) la non linéarité et le caractère mal posé du problème et (iii) le manque de données 3D ancillaires précises associées aux trajectoires. Une méthode de Monte-Carlo est proposées pour filtrer les trajectoires observées et appliquées à un cas contrôlée pour apprécier ses performances.RENNES-Agrocampus-CRD (352382323) / SudocSudocFranceF

Simultaneous online detection of isoprene and isoprene-d(2) using infrared photoacoustic spectroscopy

A photoacoustic spectrometer for the simultaneous detection of isoprene and the deuterated species [4,4-H-2]-2-methyl-1,3- butadiene (isoprene-d(2)) is presented. Using a sealed-off 13 CO2 laser a single-component detection limit of 400 ppt (isoprene)