Publications by authors named "Olivier Thomas"

184 Publications

Facet-Dependent Strain Determination in Electrochemically Synthetized Platinum Model Catalytic Nanoparticles.

Small 2021 May 18;17(18):e2007702. Epub 2021 Mar 18.

Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, Marseille, 13397, France.

Studying model nanoparticles is one approach to better understand the structural evolution of a catalyst during reactions. These nanoparticles feature well-defined faceting, offering the possibility to extract structural information as a function of facet orientation and compare it to theoretical simulations. Using Bragg Coherent X-ray Diffraction Imaging, the uniformity of electrochemically synthesized model catalysts is studied, here high-index faceted tetrahexahedral (THH) platinum nanoparticles at ambient conditions. 3D images of an individual nanoparticle are obtained, assessing not only its shape but also the specific components of the displacement and strain fields both at the surface of the nanocrystal and inside. The study reveals structural diversity of shapes and defects, and shows that the THH platinum nanoparticles present strain build-up close to facets and edges. A facet recognition algorithm is further applied to the imaged nanoparticles and provides facet-dependent structural information for all measured nanoparticles. In the context of strain engineering for model catalysts, this study provides insight into the shape-controlled synthesis of platinum nanoparticles with high-index facets.
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http://dx.doi.org/10.1002/smll.202007702DOI Listing
May 2021

New records of Demospongiae (Porifera) from Reserva Marina El Pelado (Santa Elena, Ecuador), with description of () sp. nov.

Zookeys 2021 19;1011:101-120. Epub 2021 Jan 19.

Museu Nacional, Universidade Federal do Rio de Janeiro, Depto. Invertebrados, Quinta da Boa Vista, s/n, 20940-040, Rio de Janeiro, RJ, Brazil.

The first taxonomic descriptions of the sponge diversity at El Pelado Marine Protected Area in the province of Santa Elena, Ecuador is reported. Tedania (Tedania) ecuadoriensis Jaramillo & Hajdu, is described from its shallow waters. In addition, Callyspongia (Callyspongia) aff. californica (Cruz-Barraza and Carballo 2008; Dickinson 1945) and Cliona aff. euryphylle are reported for the first time. The former species is likely distributed over 4,000 km along the Tropical Eastern Pacific, whereas the latter might be an example of a trans-isthmian lineage. An amended diagnosis for Callyspongia (Callyspongia) and an updated identification key for the subgenera of are provided.
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http://dx.doi.org/10.3897/zookeys.1011.54485DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7838150PMC
January 2021

Author Correction: Continuous scanning for Bragg coherent X-ray imaging.

Sci Rep 2020 Nov 5;10(1):19420. Epub 2020 Nov 5.

CEA Grenoble, IRIG, MEM, NRS, Univ. Grenoble Alpes, 17 rue des Martyrs, 38000, Grenoble, France.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.
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http://dx.doi.org/10.1038/s41598-020-75649-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7645716PMC
November 2020

Nebulosins: Trisubstituted Thiolane Natural Products from the Northeastern Atlantic Annelid .

J Org Chem 2020 11 22;85(21):14026-14041. Epub 2020 Oct 22.

Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway (NUI Galway), University Road, Galway H91 TK33, Ireland.

Using both multi-informative molecular network and score-based approaches as prioritization strategies, the Northeastern Atlantic marine terebellid was selected for in-depth chemical investigation. A family of 16 new metabolites named nebulosins was isolated and structurally characterized from extensive analyses of HRMS/MS and NMR spectroscopic data. Nebulosins feature an unprecedented highly substituted thiolane ring leading to up to four contiguous chiral centers. The relative configurations were assigned through a combination of NOESY analysis, spin-spin coupling constant analysis, and NMR chemical shifts measurements, while the absolute configurations were determined by comparison between experimental and theoretical ECD spectra. This family of natural product exhibits promising antioxidant activities in both ORAC and ROS assays.
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http://dx.doi.org/10.1021/acs.joc.0c02060DOI Listing
November 2020

Lipid Nanoparticles Vectorized with NFL-TBS.40-63 Peptide Target Oligodendrocytes and Promote Neurotrophin-3 Effects After Demyelination In Vitro.

Neurochem Res 2020 Nov 10;45(11):2732-2748. Epub 2020 Sep 10.

MINT, UNIV Angers, INSERM 1066, CNRS 6021, Université Bretagne Loire, Angers, France.

Promoting remyelination in multiple sclerosis is important to prevent axon degeneration, given the lack of curative treatment. Although some growth factors improve this repair, unspecific delivery to cells and potential side effects limit their therapeutic use. Thus, NFL-TBS.40-63 peptide (NFL)-known to enter specifically myelinating oligodendrocytes (OL)-was used to vectorize 100 nm diameter lipid nanoparticles (LNC), and the ability of NFL-LNC to specifically target OL from newborn rat brain was assessed in vitro. Specific uptake of DiD-labeled NFL-LNC by OL characterized by CNP and myelin basic protein was observed by confocal microscopy, as well as DiD colocalization with NFL and with Rab5-a marker of early endosomes. Unvectorized LNC did not significantly penetrate OL and there was no uptake of NFL-LNC by astrocytes. Canonical maturation of OL which extended compacted myelin-like membranes was observed by transmission electron microscopy in cells grown up to 9 days with NFL-LNC. Endocytosis of NFL-LNC appeared to depend on several pathways, as demonstrated by inhibitors. In addition, vectorized NFL-LNC adsorbed on neurotrophin-3 (NT-3) potentiated the proremyelinating effects of NT-3 after demyelination by lysophosphatidyl choline, allowing noticeably decreasing NT-3 concentration. Our results if they were confirmed in vivo suggest that NFL-vectorized LNC appear safe and could be considered as putative carriers for specific drug delivery to OL in order to increase remyelination.
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http://dx.doi.org/10.1007/s11064-020-03122-yDOI Listing
November 2020

Mapping Inversion Domain Boundaries along Single GaN Wires with Bragg Coherent X-ray Imaging.

ACS Nano 2020 Aug 10;14(8):10305-10312. Epub 2020 Aug 10.

Univiversité Grenoble Alpes, CEA Grenoble, IRIG, MEM, NRS, 17 rue des Martyrs, 38000 Grenoble, France.

Gallium nitride (GaN) is of technological importance for a wide variety of optoelectronic applications. Defects in GaN, like inversion domain boundaries (IDBs), significantly affect the electrical and optical properties of the material. We report, here, on the structural configurations of planar inversion domain boundaries inside n-doped GaN wires measured by Bragg coherent X-ray diffraction imaging. Different complex domain configurations are revealed along the wires with a 9 nm in-plane spatial resolution. We demonstrate that the IDBs change their direction of propagation along the wires, promoting Ga-terminated domains and stabilizing into {11̅00}, that is, -planes. The atomic phase shift between the Ga- and N-terminated domains was extracted using phase-retrieval algorithms, revealing an evolution of the out-of-plane displacement (∼5 pm, at maximum) between inversion domains along the wires. This work provides an accurate inner view of planar defects inside small crystals.
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http://dx.doi.org/10.1021/acsnano.0c03775DOI Listing
August 2020

Continuous scanning for Bragg coherent X-ray imaging.

Sci Rep 2020 07 29;10(1):12760. Epub 2020 Jul 29.

CEA Grenoble, IRIG, MEM, NRS, Univ. Grenoble Alpes, 17 rue des Martyrs, 38000, Grenoble, France.

We explore the use of continuous scanning during data acquisition for Bragg coherent diffraction imaging, i.e., where the sample is in continuous motion. The fidelity of continuous scanning Bragg coherent diffraction imaging is demonstrated on a single Pt nanoparticle in a flow reactor at [Formula: see text] in an Ar-based gas flowed at 50 ml/min. We show a reduction of 30% in total scan time compared to conventional step-by-step scanning. The reconstructed Bragg electron density, phase, displacement and strain fields are in excellent agreement with the results obtained from conventional step-by-step scanning. Continuous scanning will allow to minimise sample instability under the beam and will become increasingly important at diffraction-limited storage ring light sources.
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http://dx.doi.org/10.1038/s41598-020-69678-5DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7391662PMC
July 2020

Piezoelectric Properties of PbLa(ZrTi)O Thin Films Studied by In Situ X-ray Diffraction.

Materials (Basel) 2020 Jul 27;13(15). Epub 2020 Jul 27.

Aix Marseille Univ, Univ Toulon, CNRS, IM2NP, CEDEX 20, 13397 Marseille, France.

The piezoelectric properties of lanthanum-modified lead zirconate titanate PbLa(ZrTi)O thin films, with = 0, 3 and 12 mol% La, were studied by synchrotron X-ray diffraction under direct (DC) and alternating (AC) electric fields, with AC frequencies covering more than four orders of magnitude. The Bragg reflections for thin films with low lanthanum concentration exhibit a double-peak structure, indicating two contributions, whereas thin films with 12% La possess a well-defined Bragg peak with a single component. In addition, built-in electric fields are revealed for low La concentrations, while they are absent for thin films with 12% of La. For static and low frequency AC electric fields, all lanthanum-modified lead zirconate titanate thin films exhibit butterfly loops, whereas linear piezoelectric behavior is found for AC frequencies larger than 1 Hz.
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http://dx.doi.org/10.3390/ma13153338DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7435409PMC
July 2020

Comparative study on Hg bioaccumulation and biotransformation in Mediterranean and Atlantic sponge species.

Chemosphere 2020 Dec 4;260:127515. Epub 2020 Jul 4.

Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway, (NUI Galway), University Road, H91 TK33, Galway, Ireland.

In this work we present an assessment of mercury (Hg) and methyl mercury (MeHg) bioaccumulation in different species of marine sponges collected off the Northwestern Mediterranean and Northeastern Atlantic coasts. Overall the results showed significant accumulation of Hg in sponges, with the Mediterranean sponge Chondrilla nucula exhibiting the highest total Hg content (up to 0.5 mg kg) and bio-concentration factor (BCF) up to 23. A significant inter-species variability of Hg bioaccumulation was observed among species collected at the same site. The sponges, collected in marine environment contaminated with Hg show consistently higher Hg accumulation, meaning that the bioaccumulation is proportional to the Hg availability in the surrounding environment. Different extraction protocols were tested for MeHg analysis and, generally, a low MeHg ratio in Hg species (4% and 17% average for Mediterranean and Irish sponges respectively) was detected suggesting a possible demethylation process and therefore a promising role of sponges for Hg bioremediation Additionally, the Hg isotopic composition in these organisms was determined and it showed that MDF (mass dependent fractionation) is the main process in sponges, with the absence of significant MIF. This result suggests a dominant role of associated microbial population in the methylation and/or demethylation processes.
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http://dx.doi.org/10.1016/j.chemosphere.2020.127515DOI Listing
December 2020

Direct Observations of the Structural Properties of Semiconducting Polymer: Fullerene Blends under Tensile Stretching.

Materials (Basel) 2020 Jul 10;13(14). Epub 2020 Jul 10.

Institute of Physics, University of Siegen, D-57068 Siegen, Germany.

We describe the impact of tensile strains on the structural properties of thin films composed of PffBT4T-2OD π-conjugated polymer and PCBM fullerenes coated on a stretchable substrate, based on a novel approach using in situ studies of flexible organic thin films. In situ grazing incidence X-ray diffraction (GIXD) measurements were carried out to probe the ordering of polymers and to measure the strain of the polymer chains under uniaxial tensile tests. A maximum 10% tensile stretching was applied (i.e., beyond the relaxation threshold). Interestingly we found different behaviors upon stretching the polymer: fullerene blends with the modified polymer; fullerene blends with the 1,8-Diiodooctane (DIO) additive. Overall, the strain in the system was almost twice as low in the presence of additive. The inclusion of additive was found to help in stabilizing the system and, in particular, the π-π packing of the donor polymer chains.
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http://dx.doi.org/10.3390/ma13143092DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7412098PMC
July 2020

Futunamine, a Pyrrole-Imidazole Alkaloid from the Sponge aff. Collected off the Futuna Islands.

J Nat Prod 2020 07 6;83(7):2299-2304. Epub 2020 Jul 6.

Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway (NUI Galway), University Road, H91 TK33 Galway, Ireland.

The chemical investigation of the sponge aff. collected around Futuna Islands in the Pacific Ocean led to the isolation of three new dimeric pyrrole 2-aminoimidazole alkaloids (PIAs). Futunamine () features an unprecedented pyrrolo[1,2-]imidazole core, while two other new dimeric PIAs were identified as analogues of palau'amine. Together with other known PIAs isolated from this species, they were shown to exhibit anti-inflammatory and neuroprotective activities.
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http://dx.doi.org/10.1021/acs.jnatprod.0c00223DOI Listing
July 2020

Initial multicenter experience with a new high-density coloring module: impact for complex atrial arrhythmias interpretation.

J Interv Card Electrophysiol 2021 Mar 3;60(2):313-319. Epub 2020 Jul 3.

Cardiology Department, CHU Clermont-Ferrand, Clermont University, ISIT-CaVITI, 58 rue Montalembert, 63000 CHU, Clermont-Ferrand, France.

Background: High-density automated mapping of complex atrial tachycardias (ATs) requires accurate assessment of activation maps. A new local activation display module (HD coloring, Biosense Webster®) provides higher map resolution, a better delineation of potential block reducing color interpolation, and a new propagation display. We evaluated the accuracy of a dedicated local activation display compared with standard algorithm.

Methods: High-density maps from 10 AT were collected with a multipolar catheter and were displayed with standard activation or HD coloring. Six expert operators retrospectively analyzed activation maps and were asked to define (1) the tachycardia mechanism, (2) ablation target, and (3) level of difficulty to interpret those maps.

Results: Using HD coloring, operators were able to reach a correct diagnosis in 93% vs. 63%, p < 0.05 compared to standard activation maps. Time to diagnosis was shorter 1.9 ± 1.0 min vs. 3.9 ± 2.1 min, p < 0.05. Confidence level would have allowed ablation without necessity for entrainment maneuvers in 87% vs. 53%, p < 0.05. Operators would have needed to remap or proceed with multiple entrainments in 3% vs. 13% of cases, p < 0.05. Finally, ablation strategy was more accurately identified in 97% vs. 67%, p < 0.05.

Conclusion: Activation mapping with the new HD coloring module allowed a more accurate, reliable, and faster interpretation of complex ATs mechanisms compared to standard activation maps.
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http://dx.doi.org/10.1007/s10840-020-00802-1DOI Listing
March 2021

Stress Buildup Upon Crystallization of GeTe Thin Films: Curvature Measurements and Modelling.

Nanomaterials (Basel) 2020 Jun 26;10(6). Epub 2020 Jun 26.

Aix Marseille Univ, U. Toulon, CNRS, IM2NP (Institut Matériaux Microélectronique et Nanosciences de Provence), Campus St-Jérôme, 13397 Marseille CEDEX 20, France.

Phase change materials are attractive materials for non-volatile memories because of their ability to switch reversibly between an amorphous and a crystal phase. The volume change upon crystallization induces mechanical stress that needs to be understood and controlled. In this work, we monitor stress evolution during crystallization in thin GeTe films capped with SiO, using optical curvature measurements. A 150 MPa tensile stress buildup is measured when the 100 nm thick film crystallizes. Stress evolution is a result of viscosity increase with time and a tentative model is proposed that renders qualitatively the observed features.
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http://dx.doi.org/10.3390/nano10061247DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7353090PMC
June 2020

Insights into the Metabolome of the Cyanobacterium from the Lagoon of Tahiti and First Inspection of Its Variability.

Metabolites 2020 May 24;10(5). Epub 2020 May 24.

University of French Polynesia, UMR Ecosystèmes Insulaires Océaniens, LabEx CORAIL, BP6570, Faa'a, 98702 Tahiti, French Polynesia.

Cyanobacteria are known to produce a large diversity of specialized metabolites that can cause severe (eco)toxicological effects. In the lagoon of Tahiti, the benthic cyanobacterium is commonly found overgrowing the proliferative macroalga or dead branching corals. The specialized metabolome of the cyanobacterium was therefore investigated together with its variability on both substrates and changes in environmental parameters. For the study of the metabolome variability, replicates of were collected in the same location of the lagoon of Tahiti before and after a raining event, both on dead corals and on . The variability in the metabolome was inferred from a comparative non-targeted metabolomic using high resolution mass spectrometry (MS) data and a molecular network analysis built through MS/MS analyses. Oxidized fatty acid derivatives including the unusual 11-oxopalmitelaidic acid were found as major constituents of the specialized metabolome of this species. Significant variations in the metabolome of the cyanobacteria were observed, being more important with a change in environmental factors. Erucamide was found to be the main chemical marker highly present when the cyanobacterium grows on the macroalga. This study highlights the importance of combined approaches in metabolomics and molecular networks to inspect the variability in the metabolome of cyanobacteria with applications for ecological questions.
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http://dx.doi.org/10.3390/metabo10050215DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281704PMC
May 2020

Efficient, fast and inexpensive bioassay to monitor benthic microalgae toxicity: Application to Ostreopsis species.

Aquat Toxicol 2020 Jun 22;223:105485. Epub 2020 Apr 22.

Sorbonne Université, CNRS, Laboratoire d'Océanographie de Villefranche, LOV, F-06230, Villefranche-sur-Mer, France.

Even though HPLC-MS is commonly used to quantify the toxin content of Ostreopsis spp. cells, there is a need to develop easy-to-use toxicological tests to set thresholds during Ostreopsis spp. blooms. The crustacean Artemia has been widely used to evaluate the presence and toxicity of chemicals and biological contaminants and we anticipated that it could also be useful to test Ostreopsis spp. toxicity. Its relevance was first assessed by investigating the variability of the toxic effects among Ostreopsis spp. strains and throughout the dinoflagellate life cycle in combination with chemical analyses of the toxinic content by UHPLC-HRMS. After testing the toxicity of fractions prepared from Ostreopsis spp. cells, the known ova- and paly-toxins were not the only toxic metabolites to Artemia franciscana, indicating that other toxic compounds synthesized by Ostreopsis spp. still remain to be identified. To extend the bioassay to in situ monitoring, the toxicity of the benthic microalgal consortium was tested during a natural bloom of Ostreopsis cf. ovata in the NW Mediterranean Sea. The results highlight the accuracy and sensitivity of the ecotoxicological assay with Artemia franciscana to assess the toxicity of Ostreopsis spp. blooms.
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http://dx.doi.org/10.1016/j.aquatox.2020.105485DOI Listing
June 2020

A Novel High-Throughput Screening Platform Identifies Itaconate Derivatives from Marine as Inhibitors of Mesenchymal Stem Cell Differentiation.

Mar Drugs 2020 Apr 5;18(4). Epub 2020 Apr 5.

Regenerative Medicine Institute, School of Medicine, National University of Ireland Galway, H91TK33 Galway, Ireland.

Worldwide diffused diseases such as osteoarthritis, atherosclerosis or chronic kidney disease are associated with a tissue calcification process which may involve unexpected local stem cell differentiation. Current pharmacological treatments for such musculoskeletal conditions are weakly effective, sometimes extremely expensive and often absent. The potential to develop new therapies is represented by the discovery of small molecules modulating resident progenitor cell differentiation to prevent aberrant tissue calcification. The marine environment is a rich reserve of compounds with pharmaceutical potential and many novel molecules are isolated from macro and microorganisms annually. The potential of small molecules synthetized by marine filamentous fungi to influence the osteogenic and chondrogenic differentiation of human mesenchymal stem/stromal cells (hMSCs) was investigated using a novel, high-throughput automated screening platform. Metabolites synthetized by the marine-derived fungus Penicillium antarcticum were evaluated on the platform. Itaconic acid derivatives were identified as inhibitors of calcium elaboration into the matrix of osteogenically differentiated hMSCs and also inhibited hMSC chondrogenic differentiation, highlighting their capacity to impair ectopic calcification. Bioactive small molecule discovery is critical to address ectopic tissue calcification and the use of biologically relevant assays to identify naturally occurring metabolites from marine sources represents a strategy that can contribute to this effort.
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http://dx.doi.org/10.3390/md18040192DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230868PMC
April 2020

Metabolomic study of soft corals from the Colombian Caribbean: PSYCHE and H-NMR comparative analysis.

Sci Rep 2020 03 25;10(1):5417. Epub 2020 Mar 25.

Bioprospecting Research Group and Biosciences Doctoral Program, Faculty of Engineering, Campus Puente del Común, Universidad de la Sabana, 250001, Chía, Colombia.

Marine organisms have evolved to survive against predators in complex marine ecosystems via the production of chemical compounds. Soft corals (Cnidaria, Anthozoa, Octocorallia) are an important source of chemically diverse metabolites with a broad spectrum of biological activities. Herein, we perform a comparative study between high-resolution proton nuclear magnetic resonance (H-NMR) and pure shift yielded by chirp excitation (PSYCHE) experiments to analyze the metabolic profile of 24 soft corals from the Colombian Caribbean to correlate chemical fingerprints with their cytotoxic activity against three cancer cell lines (human cervical carcinoma (SiHa), human prostatic carcinoma (PC3) and human lung adenocarcinoma (A549)). All data obtained were explored using multivariate analysis using principal components analysis (PCA) and orthogonal partial least squares (OPLS) analysis. The results did not show a significant correlation between clusters using H-NMR data in the PCA and OPLS-DA models and therefore did not provide conclusive evidence; on the other hand, a metabolomic analysis of PSYCHE data obtained under the same parameters revealed that when a decoupled experiment is performed, it was possible to establish a statistically valid correlation between the chemical composition of soft corals and their cytotoxic activity against the PC3 cancer cell line, where the asperdiol and plexaurolone markers were putatively identified and related to the cytotoxic activity presented by extracts of Plexaurella sp. and Plexaura kukenthali, respectively. These results increase the speed, effectiveness and reliability of analyses for the study of this type of complex matrices.
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http://dx.doi.org/10.1038/s41598-020-62413-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7096504PMC
March 2020

Specialized microbiome of the cave-dwelling sponge Plakina kanaky (Porifera, Homoscleromorpha).

FEMS Microbiol Ecol 2020 04;96(4)

Institut Méditerranéen de Biodiversité et d'Ecologie Marine et Continentale, UMR 7263 CNRS, Aix Marseille Université, IRD, Avignon Université, Station Marine d'Endoume, Rue Batterie des Lions, Marseille 13007, France.

The recent description of the polychromatic sponge Plakina kanaky revealed original microsymbionts, with some morphotypes recorded for the first time in Homoscleromorpha and others never before observed in other sponge groups. Illumina 16S amplicon sequencing was used to characterize this microbial community by comparing contents of seven specimens of this Plakinidae with five other sponge species: one Homoscleromopha of the Oscarellidae family and four Demospongiae. A total of 256 458 sequences of the hypervariable V5-V6 region of the 16S rRNA gene were clustered into 2,829 OTUs at 97% similarity, with Proteobacteria, Poribacteria and Chloroflexi being the most abundant phyla. The Plakina kanaky specific community appeared to be mainly composed by five OTUs representing about 10% of the total microbiome. Among these, the filamentous bacterium Candidatus Entotheonella, which was among the dominant morphotypes previously observed in the mesohyl and the larvae of P. kanaky, was detected in all studied specimens. However, other original and dominant morphotypes could not be assigned to a known prokaryotic taxon. This cave dwelling sponge species harbors a distinctive microbiome composition of potential taxonomic and metabolic novelties that may be linked to its ecological success in such extreme environments.
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http://dx.doi.org/10.1093/femsec/fiaa043DOI Listing
April 2020

Cytotoxic and Anti-Inflammatory Effects of -Kaurane Derivatives Isolated from the Alpine Plant .

Molecules 2020 Jan 29;25(3). Epub 2020 Jan 29.

Laboratoire de Chimie-Toxicologie Analytique et Cellulaire (C-TAC) UMR CNRS 8038 CiTCoM Université Paris-Descartes, 4, avenue de l'Observatoire, 75006 Paris, France.

This paper reports the isolation and structural characterization of four new -kaurane derivatives from the Lamiaceae plant . Planar structures and relative configurations were determined using both mass spectrometry and nuclear magnetic resonance (1D and 2D). Absolute configurations were determined by comparing experimental and theoretical electronic circular dichroism spectra. The cytotoxic and microbial activities of all new compounds were tested. Compounds that were non-cytotoxic were further evaluated for anti-inflammatory activity.
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http://dx.doi.org/10.3390/molecules25030589DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037520PMC
January 2020

Snake Venom Gland Organoids.

Cell 2020 01;180(2):233-247.e21

Centre for Snakebite Research & Interventions, Department of Tropical Disease Biology, Liverpool School of Tropical Medicine, Liverpool L3 5QA, UK.

Wnt dependency and Lgr5 expression define multiple mammalian epithelial stem cell types. Under defined growth factor conditions, such adult stem cells (ASCs) grow as 3D organoids that recapitulate essential features of the pertinent epithelium. Here, we establish long-term expanding venom gland organoids from several snake species. The newly assembled transcriptome of the Cape coral snake reveals that organoids express high levels of toxin transcripts. Single-cell RNA sequencing of both organoids and primary tissue identifies distinct venom-expressing cell types as well as proliferative cells expressing homologs of known mammalian stem cell markers. A hard-wired regional heterogeneity in the expression of individual venom components is maintained in organoid cultures. Harvested venom peptides reflect crude venom composition and display biological activity. This study extends organoid technology to reptilian tissues and describes an experimentally tractable model system representing the snake venom gland.
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http://dx.doi.org/10.1016/j.cell.2019.11.038DOI Listing
January 2020

Variable-Wavelength Quick Scanning Nanofocused X-Ray Microscopy for In Situ Strain and Tilt Mapping.

Small 2020 Feb 21;16(6):e1905990. Epub 2020 Jan 21.

Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397, Marseille, France.

Compression of micropillars is followed in situ by a quick nanofocused X-ray scanning microscopy technique combined with 3D reciprocal space mapping. Compared to other attempts using X-ray nanobeams, it avoids any motion or vibration that would lead to a destruction of the sample. The technique consists of scanning both the energy of the incident nanofocused X-ray beam and the in-plane translations of the focusing optics along the X-ray beam. Here, the approach by imaging the strain and lattice orientation of Si micropillars and their pedestals during in situ compression is demonstrated. Varying the energy of the incident beam instead of rocking the sample and mapping the focusing optics instead of moving the sample supplies a vibration-free measurement of the reciprocal space maps without removal of the mechanical load. The maps of strain and lattice orientation are in good agreement with the ones recorded by ordinary rocking-curve scans. Variable-wavelength quick scanning X-ray microscopy opens the route for in situ strain and tilt mapping toward more diverse and complex materials environments, especially where sample manipulation is difficult.
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http://dx.doi.org/10.1002/smll.201905990DOI Listing
February 2020

From Fienup's phase retrieval techniques to regularized inversion for in-line holography: tutorial.

J Opt Soc Am A Opt Image Sci Vis 2019 Dec;36(12):D62-D80

This paper includes a tutorial on how to reconstruct in-line holograms using an inverse problems approach, starting with modeling the observations, selecting regularizations and constraints, and ending with the design of a reconstruction algorithm. A special focus is placed on the connections between the numerous alternating projections strategies derived from Fienup's phase retrieval technique and the inverse problems framework. In particular, an interpretation of Fienup's algorithm as iterates of a proximal gradient descent for a particular cost function is given. Reconstructions from simulated and experimental holograms of micrometric beads illustrate the theoretical developments. The results show that the transition from alternating projections techniques to the inverse problems formulation is straightforward and advantageous.
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http://dx.doi.org/10.1364/JOSAA.36.000D62DOI Listing
December 2019

Towards a quantitative determination of strain in Bragg Coherent X-ray Diffraction Imaging: artefacts and sign convention in reconstructions.

Sci Rep 2019 Nov 22;9(1):17357. Epub 2019 Nov 22.

Aix Marseille Université, CNRS, Université de Toulon, IM2NP UMR 7334, 13397, Marseille, France.

Bragg coherent X-ray diffraction imaging (BCDI) has emerged as a powerful technique to image the local displacement field and strain in nanocrystals, in three dimensions with nanometric spatial resolution. However, BCDI relies on both dataset collection and phase retrieval algorithms that can induce artefacts in the reconstruction. Phase retrieval algorithms are based on the fast Fourier transform (FFT). We demonstrate how to calculate the displacement field inside a nanocrystal from its reconstructed phase depending on the mathematical convention used for the FFT. We use numerical simulations to quantify the influence of experimentally unavoidable detector deficiencies such as blind areas or limited dynamic range as well as post-processing filtering on the reconstruction. We also propose a criterion for the isosurface determination of the object, based on the histogram of the reconstructed modulus. Finally, we study the capability of the phasing algorithm to quantitatively retrieve the surface strain (i.e., the strain of the surface voxels). This work emphasizes many aspects that have been neglected so far in BCDI, which need to be understood for a quantitative analysis of displacement and strain based on this technique. It concludes with the optimization of experimental parameters to improve throughput and to establish BCDI as a reliable 3D nano-imaging technique.
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http://dx.doi.org/10.1038/s41598-019-53774-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6874548PMC
November 2019

Brominated Bisindole Alkaloids from the Celtic Sea Sponge .

Molecules 2019 Oct 29;24(21). Epub 2019 Oct 29.

Marine Biodiscovery Laboratory, School of Chemistry and Ryan Institute, National University of Ireland Galway, University Road, Galway H91 TK33, Ireland.

As part of an ongoing program to identify new bioactive compounds from Irish marine bioresources, we selected the subtidal sponge for chemical study, as fractions of this species displayed interesting cytotoxic bioactivities and chemical profiles. The first chemical investigation of this marine species led to the discovery of two new bisindole alkaloids of the topsentin family, together with six other known indole alkaloids. Missing the usual central core featured by the representatives of these marine natural products, the new metabolites may represent key biosynthetic intermediates for other known bisindoles. These compounds were found to exhibit weak cytotoxic activity against HeLa tumour cells, suggesting a specificity towards previously screened carcinoma and leukaemia cells.
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http://dx.doi.org/10.3390/molecules24213890DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6864463PMC
October 2019

Marine natural products from zoantharians: bioactivity, biosynthesis, systematics, and ecological roles.

Nat Prod Rep 2020 04 31;37(4):515-540. Epub 2019 Oct 31.

Marine Biodiscovery, School of Chemistry and Ryan Institute, National University of Ireland Galway (NUI Galway), University Road, H91 TK33 Galway, Ireland.

Covering: up to the end of 2018Zoantharians, also improperly known as zoanthids or colonial anemones, are well known by aquarists because of their ease of use in aquaria but also because of their splendid colours. However, high concentrations of the highly toxic palytoxin found in some species of zoantharians maintained in reef aquaria has raised some issues recently, unveiling at the same time a rather unknown chemical diversity hidden in these marine beauties. Herein, we report the structure of the metabolites described in all species of zoantharians up to the end of 2018 and their associated biological activities. As sessile invertebrates, zoantharians harbour a rich diversity of micro-organisms that can play a role in the biosynthesis of these natural products and we detail the current hypotheses on the metabolic pathways leading to the identified ecdysteroids, zoanthoxanthins, zoanthamines, palytoxins and others. Finally, we assess the possible use of these metabolites in the systematics of such a complex group of marine invertebrates and we discuss their possible ecological roles. Altogether, this review brings some insights into the rich chemical diversity of zoantharians and their potential for marine biodiscovery and marine ecology.
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http://dx.doi.org/10.1039/c9np00043gDOI Listing
April 2020

Genome Mining Coupled with OSMAC-Based Cultivation Reveal Differential Production of Surugamide A by the Marine Sponge Isolate sp. SM17 When Compared to Its Terrestrial Relative J1074.

Microorganisms 2019 Sep 26;7(10). Epub 2019 Sep 26.

School of Microbiology, University College Cork, T12 YN60 Cork, Ireland.

Much recent interest has arisen in investigating isolates derived from the marine environment in the search for new bioactive compounds, particularly those found in association with marine invertebrates, such as sponges. Among these new compounds recently identified from marine isolates are the octapeptidic surugamides, which have been shown to possess anticancer and antifungal activities. By employing genome mining followed by an one strain many compounds (OSMAC)-based approach, we have identified the previously unreported capability of a marine sponge-derived isolate, namely sp. SM17, to produce surugamide A. Phylogenomics analyses provided novel insights on the distribution and conservation of the surugamides biosynthetic gene cluster ( BGC) and suggested a closer relatedness between marine-derived BGCs than their terrestrially derived counterparts. Subsequent analysis showed differential production of surugamide A when comparing the closely related marine and terrestrial isolates, namely sp. SM17 and J1074. SM17 produced higher levels of surugamide A than J1074 under all conditions tested, and in particular producing >13-fold higher levels when grown in YD and 3-fold higher levels in SYP-NaCl medium. In addition, surugamide A production was repressed in TSB and YD medium, suggesting that carbon catabolite repression (CCR) may influence the production of surugamides in these strains.
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http://dx.doi.org/10.3390/microorganisms7100394DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6843307PMC
September 2019

Interstitial Flow Recapitulates Gemcitabine Chemoresistance in A 3D Microfluidic Pancreatic Ductal Adenocarcinoma Model by Induction of Multidrug Resistance Proteins.

Int J Mol Sci 2019 Sep 19;20(18). Epub 2019 Sep 19.

Mimetas BV, J.H. Oortweg 19, 2333 CH Leiden, The Netherlands.

Pancreatic Ductal Adenocarcinoma (PDAC) is one of the most lethal cancers due to a high chemoresistance and poor vascularization, which results in an ineffective systemic therapy. PDAC is characterized by a high intratumoral pressure, which is not captured by current 2D and 3D in vitro models. Here, we demonstrated a 3D microfluidic interstitial flow model to mimic the intratumoral pressure in PDAC. We found that subjecting the S2-028 PDAC cell line to interstitial flow inhibits the proliferation, while maintaining a high viability. We observed increased gemcitabine chemoresistance, with an almost nine-fold higher EC50 as compared to a monolayer culture (31 nM versus 277 nM), and an alleviated expression and function of the multidrug resistance protein (MRP) family. In conclusion, we developed a 3D cell culture modality for studying intratissue pressure and flow that exhibits more predictive capabilities than conventional 2D cell culture and is less time-consuming, and more scalable and accessible than animal models. This increase in microphysiological relevance might support improved efficiency in the drug development pipeline.
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http://dx.doi.org/10.3390/ijms20184647DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6770899PMC
September 2019

The Tara Pacific expedition-A pan-ecosystemic approach of the "-omics" complexity of coral reef holobionts across the Pacific Ocean.

PLoS Biol 2019 09 23;17(9):e3000483. Epub 2019 Sep 23.

Centre Scientifique de Monaco, Monte Carlo, Principality of Monaco.

Coral reefs are the most diverse habitats in the marine realm. Their productivity, structural complexity, and biodiversity critically depend on ecosystem services provided by corals that are threatened because of climate change effects-in particular, ocean warming and acidification. The coral holobiont is composed of the coral animal host, endosymbiotic dinoflagellates, associated viruses, bacteria, and other microeukaryotes. In particular, the mandatory photosymbiosis with microalgae of the family Symbiodiniaceae and its consequences on the evolution, physiology, and stress resilience of the coral holobiont have yet to be fully elucidated. The functioning of the holobiont as a whole is largely unknown, although bacteria and viruses are presumed to play roles in metabolic interactions, immunity, and stress tolerance. In the context of climate change and anthropogenic threats on coral reef ecosystems, the Tara Pacific project aims to provide a baseline of the "-omics" complexity of the coral holobiont and its ecosystem across the Pacific Ocean and for various oceanographically distinct defined areas. Inspired by the previous Tara Oceans expeditions, the Tara Pacific expedition (2016-2018) has applied a pan-ecosystemic approach on coral reefs throughout the Pacific Ocean, drawing an east-west transect from Panama to Papua New Guinea and a south-north transect from Australia to Japan, sampling corals throughout 32 island systems with local replicates. Tara Pacific has developed and applied state-of-the-art technologies in very-high-throughput genetic sequencing and molecular analysis to reveal the entire microbial and chemical diversity as well as functional traits associated with coral holobionts, together with various measures on environmental forcing. This ambitious project aims at revealing a massive amount of novel biodiversity, shedding light on the complex links between genomes, transcriptomes, metabolomes, organisms, and ecosystem functions in coral reefs and providing a reference of the biological state of modern coral reefs in the Anthropocene.
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http://dx.doi.org/10.1371/journal.pbio.3000483DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6776362PMC
September 2019

3D human microvessel-on-a-chip model for studying monocyte-to-endothelium adhesion under flow - application in systems toxicology.

ALTEX 2020 22;37(1):47-63. Epub 2019 Aug 22.

MIMETAS BV, Leiden, The Netherlands.

Lifestyle and genetic factors can lead to the development of atherosclerosis and, ultimately, cardiovascular adverse events. Rodent models are commonly used to investigate mechanism(s) of atherogenesis. However, the 3Rs principles, aiming to limit animal testing, encourage the scientific community to develop new physiologically relevant in vitro alternatives. Leveraging the 96-chip OrganoPlate®, a microfluidic platform, we have established a three-dimensional (3D) model of endothelial microvessels-on-a-chip under flow using primary human coronary arterial endothelial cells. As functional readout, we have set up an assay to measure the adhesion of monocytes to the lumen of perfused microvessels. For monitoring molecular changes in microvessels, we have established the staining and quantification of specific protein markers of inflammation and oxidative stress using high content imaging, as well as analyzed transcriptome changes using microarrays. To demonstrate its usefulness in systems toxicology, we leveraged our 3D vasculature-on-a-chip model to assess the impact of the Tobacco Heating System (THS) 2.2, a candidate modified risk tobacco product, and the 3R4F reference cigarette on the adhesion of monocytic cells to endothelial microvessels. Our results show that THS 2.2 aerosol-conditioned medium had a reduced effect on monocyte-endothelium adhesion compared with 3R4F smoke-conditioned medium. In conclusion, we have established a relevant 3D vasculature-on-a-chip model for investigating leukocyte-endothelial microvessel adhesion. A case study illustrates how the model can be used for product testing in the context of systems toxicology-based risk assessment. The current model and its potential further development options also open perspectives of applications in vascular disease research and drug discovery.
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http://dx.doi.org/10.14573/altex.1811301DOI Listing
November 2020

Complex organized atrial arrhythmia with alternation between two circuits involving probable epicardial connections: An ultra-high-density mapping study.

HeartRhythm Case Rep 2019 Jul 3;5(7):359-362. Epub 2019 Apr 3.

Department of Electrophysiology and Pacing, Centre Médico-Chirurgical Ambroise Paré, Neuilly-sur-Seine, France.

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http://dx.doi.org/10.1016/j.hrcr.2019.03.010DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6630150PMC
July 2019