Laboratoire d'optique et biosciences
Laboratoire d'optique et biosciences
Laboratoire d'optique et biosciences

Articles

  • High-throughput tuning of ovarian cancer spheroids for on-chip invasion assays
    • Chen Changchong
    • He Yong
    • Lopez Elliot
    • Carreiras Franck
    • Yamada Ayako
    • Schanne-Klein Marie-Claire
    • Lambert Ambroise
    • Chen Yong
    • Aimé Carole
    Micro and Nano Engineering, Elsevier , 2022, 15, pp.100138 . We developed an invasion assay by using microfabricated culture devices. First, ovarian tumor spheroids were generated with a culture patch device consisting of an agarose membrane formed with a honeycomb microframe – the patch – and gelatin nanofiber backbone. By changing the dimensions of the honeycomb compartments we were able to control the number of cells and size of the spheroids. When the spheroids were placed on a patch coated with a thin membrane of fibrillary type I collagen, spheroid disruption was observed due to substrate induced cell migration. This process is straightforward and should be applicable to other cancer types, as well as assays under microfluidic conditions, thereby holding the potential for use in tumor modeling and anti-cancer drug development. (10.1016/j.mne.2022.100138)
    DOI : 10.1016/j.mne.2022.100138
  • Erratum: Electric field measurements in plasmas: how focusing strongly distorts the E-FISH signal (2020 Plasma Sources Sci. Technol. 29 125002)
    • Chng Tat Loon
    • Starikovskaia Svetlana
    • Schanne-Klein Marie-Claire
    Plasma Sources Science and Technology, IOP Publishing , 2022, 31 (5), pp.059601 . (10.1088/1361-6595/ac601d)
    DOI : 10.1088/1361-6595/ac601d
  • Efficient Biocatalytic System for Biosensing by Combining Metal–Organic Framework (MOF)-Based Nanozymes and G-Quadruplex (G4)-DNAzymes
    • Mao Xuanxiang
    • He Fangni
    • Qiu Dehui
    • Wei Shijiong
    • Luo Rengan
    • Chen Yun
    • Zhang Xiaobo
    • Lei Jianping
    • Monchaud David
    • Mergny Jean-Louis
    • Ju Huangxian
    • Zhou Jun
    Analytical Chemistry, American Chemical Society , 2022, 94 (20), pp.7295-7302 . A high catalytic efficiency associated with a robust chemical structure are among the ultimate goals when developing new biocatalytic systems for biosensing applications. To get ever closer to these goals, we report here on a combination of metal-organic framework (MOF)-based nanozymes and a G-quadruplex (G4)-based catalytic system known as G4-DNAzyme. This approach aims at combining the advantages of both partners (chiefly, the robustness of the former and the modularity of the latter). To this end, we used MIL-53(Fe) MOF and linked it covalently to a G4-forming sequence (F3TC), itself covalently linked to its cofactor hemin. The resulting complex (referred to as MIL-53(Fe)/G4-hemin) exhibited exquisite peroxidase-mimicking oxidation activity and an excellent robustness (being stored in water for weeks). These properties were exploited to devise a new biosensing system based on a cascade of reactions catalyzed by the nanozyme (ABTS oxidation) and an enzyme, the alkaline phosphatase (or ALP, ascorbic acid 2-phosphate dephosphorylation). The product of the latter poisoning the former, we thus designed a biosensor for ALP (a marker of bone diseases and cancers), with a very low limit of detection (LOD, 0.02 U L-1), which is operative in human plasma samples. (10.1021/acs.analchem.2c00600)
    DOI : 10.1021/acs.analchem.2c00600
  • Stabilization of a DNA aptamer by ligand binding
    • Santos Tiago
    • Lopes-Nunes Jéssica
    • Alexandre Daniela
    • Miranda André
    • Figueiredo Joana
    • Silva Micael
    • Mergny Jean-Louis
    • Cruz Carla
    Biochimie, Elsevier , 2022, S0300-9084 (22), pp.00114-6 . G-rich aptamers such as AS1411 are small oligonucleotides that present several benefits comparatively to monoclonal antibodies, since they are easier to manufacture and store, have small size and do not stimulate an immune response. We analyzed AT11-B1, a modified sequence of AT11 (itself a modified version of AS1411), in which one thymine was removed from the bulge region. We studied G-quadruplex (G4) formation/stabilization using PhenDC3, PDS, BRACO-19, TMPyP4 and 360A ligands by different biophysical techniques, namely circular dichroism (CD), Förster resonance energy transfer (FRET-melting) and nuclear magnetic resonance (NMR). The CD spectra showed that AT11-B1 adopts a predominant G4 of parallel topology when the buffer contains KCl or when ligands are added. PhenDC3 induced a ΔTm of 30 °C or more of the G4 structure as shown by CD- and FRET-melting experiments. The ligands demonstrate high affinity for AT11-B1 G4 and the NMR studies revealed that the AT11-B1 G4 involves four G-tetrad layers. The in silico studies suggest that all ligands bind AT11-B1 G4, namely, by stacking interactions, except PDS that may bind to the loop/groove interface. In addition, molecular dynamics simulations revealed that nucleolin (NCL) interacts with the AT11-B1 G4 structure through the RNA binding domain (RBD) 2 and the 12-residue linker between RBD1,2. Moreover, AT11-B1 G4 was internalized into a NCL-positive tongue squamous cell carcinoma cell line. In a nutshell, this study may help the identification of the ligands scaffolds to bind and stabilize AT11-B1, improving the targeting towards NCL that is overexpressed in cancer cells. (10.1016/j.biochi.2022.05.002)
    DOI : 10.1016/j.biochi.2022.05.002
  • Perception des risques et résilience climatique chez les maraîchers dans la zone soudano-sahélienne : cas de Mandaka (zone montagneuse) et Meskine (zone de plaine)
    • Dzokom Alexis
    Sahel Nature Consulting Revue, Sahel Nature Consulting Revue (March 2025) , 2022, 02 (03), pp.01-26 . La zone soudano-sahélienne est caractérisée par des conditions climatiques incertaines, notamment des pluies irrégulières et des épisodes de sécheresse récurrents, qui impactent fortement la production maraîchère. Cette étude vise à analyser la perception des risques climatiques par les maraîchers et son lien avec les stratégies d’adaptation et de résilience, en mettant l’accent sur le rôle des pratiques agro écologiques. Les données ont été collectées dans deux localités contrastées : Mandaka (zone montagneuse) et Meskine (zone de plaine). L’approche méthodologique combinait enquêtes semi-structurées, groupes de discussion et analyse statistique des réponses, ainsi qu’une analyse comparative des pratiques agro écologiques mises en œuvre. Les résultats indiquent que la perception des risques influence directement l’adoption de stratégies adaptées, notamment la diversification des cultures, l’usage de compost organique et la conservation de l’eau. La résilience des maraîchers est fortement renforcée par l’adoption systématique des pratiques agro écologiques et la transmission des savoirs locaux. Les recommandations incluent le renforcement des formations agro écologiques et l’intégration des perceptions paysannes dans les politiques climatiques locales.
  • Molecular insights into the role of heme in the transcriptional regulatory system AppA/PpsR.
    • Kapetanaki Sofia
    • Fekete Zsuzsanna
    • Dorlet Pierre
    • Vos Marten
    • Liebl Ursula
    • Lukacs Andras
    Biophysical Journal, Biophysical Society , 2022, 121, pp.2135-2151 . Heme has been shown to have a crucial role in the signal transduction mechanism of the facultative photoheterotrophic bacterium Rhodobacter sphaeroides. It interacts with the transcriptional regulatory complex AppA/PpsR, in which AppA and PpsR function as the antirepressor and repressor, respectively, of photosynthesis gene expression. The mechanism, however, of this interaction remains incompletely understood. In this study, we combined electron paramagnetic resonance (EPR) spectroscopy and Förster resonance energy transfer (FRET) to demonstrate the ligation of heme in PpsR with a proposed cysteine residue. We show that heme binding in AppA affects the fluorescent properties of the dark-adapted state of the protein, suggesting a less constrained flavin environment compared with the absence of heme and the light-adapted state. We performed ultrafast transient absorption measurements in order to reveal potential differences in the dynamic processes in the full-length AppA and its heme-binding domain alone. Comparison of the CO-binding dynamics demonstrates a more open heme pocket in the holo-protein, qualitatively similar to what has been observed in the CO sensor RcoM-2, and suggests a communication path between the blue-light-using flavin (BLUF) and sensing containing heme instead of cobalamin (SCHIC) domains of AppA. We have also examined quantitatively the affinity of PpsR to bind to individual DNA fragments of the puc promoter using fluorescence anisotropy assays. We conclude that oligomerization of PpsR is initially triggered by binding of one of the two DNA fragments and observe a ∼10-fold increase in the dissociation constant Kd for DNA binding upon heme binding to PpsR. Our study provides significant new insight at the molecular level on the regulatory role of heme that modulates the complex transcriptional regulation in R. sphaeroides and supports the two levels of heme signaling, via its binding to AppA and PpsR and via the sensing of gases like oxygen. (10.1016/j.bpj.2022.04.031)
    DOI : 10.1016/j.bpj.2022.04.031
  • Thiosugar naphthalene diimide conjugates: G-quadruplex ligands with antiparasitic and anticancer activity
    • Belmonte-Reche Efres
    • Benassi Alessandra
    • Peñalver Pablo
    • Cucchiarini Anne
    • Guédin Aurore
    • Mergny Jean Louis
    • Rosu Frèdèric
    • Gabelica Valerie
    • Freccero Mauro
    • Doria Filippo
    • Morales Juan Carlos
    European Journal of Medicinal Chemistry, Elsevier , 2022, 232, pp.114183 . Glycosyl conjugation to drugs is a strategy being used to take advantage of glucose transporters (GLUT) overexpression in cancer cells in comparison with non-cancerous cells. Its extension to the conjugation of drugs to thiosugars tries to exploit their higher biostability when compared to O-glycosides. Here, we have synthesized a series of thiosugar naphthalene diimide conjugates as G-quadruplex ligands and have explored modifications of the amino sidechain comparing dimethyl amino and morpholino groups. Then, we studied their antiproliferative activity in colon cancer cells, and their antiparasitic activity in T. brucei and L. major parasites, together with their ability to bind quadruplexes and their cellular uptake and location. We observed higher toxicity for the sugar-NDI-NMe2 derivatives than for the sugar-NDI-morph compounds, both in mammalian cells and in parasites. Our experiments indicate that a less efficient binding to quadruplexes and a worse cellular uptake of the carb-NDI-morph derivatives could be the reasons for these differences. We found small variations in cytotoxicity between O-carb-NDIs and S-carb-NDIs, except against non-cancerous human fibroblasts MRC-5, where thiosugar-NDIs tend to be less toxic. This leads to a notable selectivity for β-thiomaltosyl-NDI-NMe212 (9.8 fold), with an IC50 of 0.3 μM against HT-29 cells. Finally, the antiparasitic activity observed for the carb-NDI-NMe2 derivatives against T. brucei was in the nanomolar range with a good selectivity index in the range of 30- to 69- fold. (10.1016/j.ejmech.2022.114183)
    DOI : 10.1016/j.ejmech.2022.114183
  • Screening of Scaffolds for the Design of G-Quadruplex Ligands
    • Figueiredo Joana
    • Peitinho David
    • Cabral Campello Maria Paula
    • Oliveira Maria Cristina
    • Paulo António
    • Mergny Jean-Louis
    • Cruz Carla
    Applied Sciences, Multidisciplinary digital publishing institute (MDPI) , 2022, 12, pp.2170 . In the last decade, progress has been made in G-quadruplex (G4) ligands development, but for most compounds, the ligand binding mode is speculative or based on low resolution methods, with its discovery based on structure-based approaches. Herein, we report the synthesis of small (MW < 400 Da) heterocycle compounds, containing different aromatic scaffolds, such as phenyl, quinoline, naphthalene, phenanthroline and acridine moieties, in order to explore their stabilization effect towards different DNA G4s, such as those found in c-MYC, KRAS21 and VEGF promoters, 21G human telomeric motif and pre-MIR150. The fluorescence resonance energy transfer (FRET) melting assay indicates that the acridine moiety is the most active scaffold, followed by phenanthroline. The different scaffolds are promising in terms of drug-like properties and, in general, the IC50 values of the respective heterocycle compounds are lower in a cancer cell line, when compared with a normal cell line. The acridine derivative C5NH2 has the most favorable cytotoxic profile in terms of cell selectivity. (10.3390/app12042170)
    DOI : 10.3390/app12042170
  • Live 3D imaging and mapping of shear stresses within tissues using incompressible elastic beads
    • Souchaud Alexandre
    • Boutillon Arthur
    • Charron Gaëlle
    • Asnacios Atef
    • Noûs Camille
    • David Nicolas
    • Graner François
    • Gallet François
    Development (Cambridge, England), Company of Biologists , 2022, 149 (4), pp.dev199765 . To investigate the role of mechanical constraints in morphogenesis and development, we have developed a pipeline of techniques based on incompressible elastic sensors. These techniques combine the advantages of incompressible liquid droplets, which have been used as precise in situ shear stress sensors, and of elastic compressible beads, which are easier to tune and to use. Droplets of a polydimethylsiloxane mix, made fluorescent through specific covalent binding to a rhodamin dye, are produced by a microfluidics device. The elastomer rigidity after polymerization is adjusted to the tissue rigidity. Its mechanical properties are carefully calibrated in situ, for a sensor embedded in a cell aggregate submitted to uniaxial compression. The local shear stress tensor is retrieved from the sensor shape, accurately reconstructed through an active contour method. In vitro, within cell aggregates, and in vivo, in the prechordal plate of the zebrafish embryo during gastrulation, our pipeline of techniques demonstrates its efficiency to directly measure the three dimensional shear stress repartition within a tissue. (10.1242/dev.199765)
    DOI : 10.1242/dev.199765
  • Intravital deep-tumor single-beam 3-photon, 4-photon, and harmonic microscopy
    • Bakker Gert-Jan
    • Weischer Sarah
    • Ferrer Ortas Júlia
    • Heidelin Judith
    • Andresen Volker
    • Beutler Marcus
    • Beaurepaire Emmanuel
    • Friedl Peter
    eLife, eLife Sciences Publication , 2022, 11, pp.e63776 . Three-photon excitation has recently been demonstrated as an effective method to perform intravital microscopy in deep, previously inaccessible regions of the mouse brain. The applicability of 3-photon excitation for deep imaging of other, more heterogeneous tissue types has been much less explored. In this work, we analyze the benefit of high-pulse-energy 1 MHz pulse-repetition-rate infrared excitation near 1300 and 1700 nm for in-depth imaging of tumorous and bone tissue. We show that this excitation regime provides a more than 2-fold increased imaging depth in tumor and bone tissue compared to the illumination conditions commonly used in 2-photon excitation, due to improved excitation confinement and reduced scattering. We also show that simultaneous 3- and 4-photon processes can be effectively induced with a single laser line, enabling the combined detection of blue to far-red fluorescence together with second and third harmonic generation without chromatic aberration, at excitation intensities compatible with live tissue imaging. Finally, we analyze photoperturbation thresholds in this excitation regime and derive setpoints for safe cell imaging. Together, these results indicate that infrared high-pulse-energy low-repetition-rate excitation opens novel perspectives for intravital deep-tissue microscopy of multiple parameters in strongly scattering tissues and organs. (10.7554/eLife.63776)
    DOI : 10.7554/eLife.63776
  • Portrait of a Family of Highly Stabilizing and Selective Guanine Quadruplex Platinum(II)‐Based Binders
    • Miron Caitlin
    • Chen Mickey
    • Mergny Jean‐louis
    • Petitjean Anne
    Chemistry - A European Journal, Wiley-VCH Verlag , 2022, 28 (7), pp.e202103839 . The long-standing history of platinum coordination complexes in nucleic acid recognition attests to the unique suitability of such species for therapeutic applications. Here, we report the synthetic exploration and development of a family of di-imine ligands, and their platinum(II) complexes, elaborated on a 3-(2-pyridyl)-[1,2,4]triazolo[4,3-a]pyridine platform which, in its unsubstituted form, has recently been shown to display exceptional capabilities for guanine quadruplex (G4) targeting. The identification of facile, high-yielding synthetic methods for the derivatization of this platform for the incorporation of additional sites of interactions with guanine quadruplex loops and grooves, along with the optimization of platinum(II) complexation methods, are discussed. Gratifyingly, preliminary biophysical screening of this novel family of binders validates all but one family members as robust G4 binders and highlights enhanced selectivity for quadruplex versus duplex DNA compared to the parent compound. These results bear promise for practical developments based on this platform. (10.1002/chem.202103839)
    DOI : 10.1002/chem.202103839
  • Highly Sensitive Biosensing Applications of a Magnetically Immobilizable Covalent G-Quadruplex-Hemin DNAzyme Catalytic System
    • Chen Yun
    • Qiu Dehui
    • Zhang Xiaobo
    • Liu Yuan
    • Cheng Mingpan
    • Lei Jianping
    • Mergny Jean-Louis
    • Ju Huangxian
    • Zhou Jun
    Analytical Chemistry, American Chemical Society , 2022, 94 (2212-2219), pp.acs.analchem.1c04842 . (10.1021/acs.analchem.1c04842)
    DOI : 10.1021/acs.analchem.1c04842
  • Guidance by followers ensures long-range coordination of cell migration through α-Catenin mechanoperception
    • Boutillon Arthur
    • Escot Sophie
    • Elouin Amélie
    • Jahn Diego
    • González-Tirado Sebastián
    • Starruss Jörn
    • Brusch Lutz
    • David Nicolas B
    Developmental Cell, Elsevier , 2022 . Morphogenesis, wound healing and some cancer metastases depend upon migration of cell collectives that need to be guided to their destination as well as coordinated with other cell movements. During zebrafish gastrulation, extension of the embryonic axis is led by the mesendodermal polster that migrates towards the animal pole, followed by axial mesoderm that is undergoing convergence and extension. We here investigate how polster cells are guided towards the animal pole. Using a combination of precise laser ablations, advanced transplantations and functional as well as silico approaches, we establish that the directional information guiding polster cells is mechanical, and is provided by the anteriorward migration of the following cells. This information is detected by cell-cell contact through E-Cadherin/α-Catenin mechanotransduction and propagates from cell to cell over the whole tissue. Such guidance of migrating cells by followers ensures long-range coordination of movements and developmental robustness. (10.1016/j.devcel.2022.05.001)
    DOI : 10.1016/j.devcel.2022.05.001
  • Ultrafast photooxidation of protein-bound anionic flavin radicals
    • Zhuang Bo
    • Ramodiharilafy Rivo
    • Liebl Ursula
    • Aleksandrov Alexey
    • Vos Marten H.
    Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences , 2022, 119 (8), pp.e2118924119 . The photophysical properties of anionic semireduced flavin radicals are largely unknown despite their importance in numerous biochemical reactions. Here, we studied the photoproducts of these intrinsically unstable species in five different flavoprotein oxidases where they can be stabilized, including the well-characterized glucose oxidase. Using ultrafast absorption and fluorescence spectroscopy, we unexpectedly found that photoexcitation systematically results in the oxidation of protein-bound anionic flavin radicals on a time scale of less than ∼100 fs. The thus generated photoproducts decay back in the remarkably narrow 10- to 20-ps time range. Based on molecular dynamics and quantum mechanics computations, positively charged active-site histidine and arginine residues are proposed to be the electron acceptor candidates. Altogether, we established that, in addition to the commonly known and extensively studied photoreduction of oxidized flavins in flavoproteins, the reverse process (i.e., the photooxidation of anionic flavin radicals) can also occur. We propose that this process may constitute an excited-state deactivation pathway for protein-bound anionic flavin radicals in general. This hitherto undocumented photochemical reaction in flavoproteins further extends the family of flavin photocycles. (10.1073/pnas.2118924119)
    DOI : 10.1073/pnas.2118924119
  • Photochemical and Molecular Dynamics Studies of Halide Binding in Flavoenzyme Glucose Oxidase
    • Zhuang Bo
    • Vos Marten
    • Aleksandrov Alexey
    ChemBioChem, Wiley-VCH Verlag , 2022, 23 (19), pp.e202200227 . Glucose oxidase (GOX), a characteristic flavoprotein oxidase with widespread industrial applications, binds fluoride (F−) and chloride (Cl−). We investigated binding properties of halide inhibitors of GOX through time-resolved spectral characterization of flavin-related photochemical processes and molecular dynamic simulations. Cl− and F− bind differently to the protein active site and have substantial but opposite effects on the population and decay of the flavin excited state. Cl− binds closer to the flavin, whose excited-state decays in <100 fs due to anion-π interactions. Such interactions appear absent in F− binding, which, however, significantly increases the active-site rigidity leading to more homogeneous, picosecond fluorescence decay kinetics. These findings are discussed in relation to the mechanism of halide inhibition of GOX by occupying the accommodation site of catalytic intermediates and increasing the active-site rigidity (10.1002/cbic.202200227)
    DOI : 10.1002/cbic.202200227
  • G-quadruplexes in helminth parasites
    • Cantara Alessio
    • Luo Yu
    • Dobrovolná Michaela
    • Bohalova Natalia
    • Fojta Miroslav
    • Verga Daniela
    • Guittat Lionel
    • Cucchiarini Anne
    • Savrimoutou Solène
    • Häberli Cécile
    • Guillon Jean
    • Keiser Jennifer
    • Brázda Václav
    • Mergny Jean
    Nucleic Acids Research, Oxford University Press , 2022, 50 (5), pp.2719–2735 . Parasitic helminths infecting humans are highly prevalent infecting ∼2 billion people worldwide, causing inflammatory responses, malnutrition and anemia that are the primary cause of morbidity. In addition, helminth infections of cattle have a significant economic impact on livestock production, milk yield and fertility. The etiological agents of helminth infections are mainly Nematodes (roundworms) and Platyhelminths (flatworms). G-quadruplexes (G4) are unusual nucleic acid structures formed by G-rich sequences that can be recognized by specific G4 ligands. Here we used the G4Hunter Web Tool to identify and compare potential G4 sequences (PQS) in the nuclear and mitochondrial genomes of various helminths to identify G4 ligand targets. PQS are nonrandomly distributed in these genomes and often located in the proximity of genes. Unexpectedly, a Nematode, Ascaris lumbricoides, was found to be highly enriched in stable PQS. This species can tolerate high-stability G4 structures, which are not counter selected at all, in stark contrast to most other species. We experimentally confirmed G4 formation for sequences found in four different parasitic helminths. Small molecules able to selectively recognize G4 were found to bind to Schistosoma mansoni G4 motifs. Two of these ligands demonstrated potent activity both against larval and adult stages of this parasite. (10.1093/nar/gkac129)
    DOI : 10.1093/nar/gkac129
  • Flavoprotein Photochemistry: Fundamental Processes and Photocatalytic Perspectives
    • Zhuang Bo
    • Liebl Ursula
    • Vos Marten H.
    Journal of Physical Chemistry B, American Chemical Society , 2022, 126, pp.3199-3207 . Flavins are highly versatile redox-active and colored cofactors in a large variety of proteins. These do include photoenzymes and photoreceptors, although the vast majority performs non-light-driven physiological functions. Nevertheless, electron transfer between flavins and specific nearby amino acid residues (in particular tyrosine, tryptophan, and presumably histidine and arginine) takes place upon excitation of flavin in many flavoproteins. For oxidized flavoproteins these reactions potentially have a photoprotective role. In this Perspective, we outline work on the characterization of early reaction intermediates not only in the relatively well-studied resting oxidized forms but also in the fully reduced and the intrinsically unstable semireduced forms, where ultrafast photooxidation of flavin was recently demonstrated. Along different lines, flavoprotein-based novel photocatalysts for biotechnological applications are presently emerging, employing both substrate photooxidation and photoreduction strategies. Deep insight into the fundamental flavin photochemical reactions may help in guiding and optimizing their development and in the exploration of novel photocatalytic approaches. (10.1021/acs.jpcb.2c00969)
    DOI : 10.1021/acs.jpcb.2c00969
  • Enhanced intrapulse difference frequency generation in the mid-infrared by a spectrally dependent polarization state
    • Bournet Q.
    • Guichard F.
    • Natile M.
    • Zaouter Y.
    • Joffre M.
    • Bonvalet A.
    • Pupeza I.
    • Hofer C.
    • Druon F.
    • Hanna Marc
    • Georges Patrick
    Optics Letters, Optical Society of America - OSA Publishing , 2022, 47 (2), pp.261 . We present a technique to optimize the intrapulse difference frequency generation efficiency for mid-IR generation. The approach employs a multi-order waveplate that is designed to selectively rotate the polarization state of the incoming spectral components on the relevant orthogonal axes for subsequent nonlinear interaction. We demonstrate a significant increase of the mid-IR average power generated by a factor ≥ 2.5 compared to the conventional scheme, due to an optimally distributed number of photons enrolled in the difference frequency generation process. (10.1364/OL.444908)
    DOI : 10.1364/OL.444908
  • Made of Combustible Briquette By Using Azadirachta indica Dead Leaves Associed to Stem Of Sorghum sp
    • Dzokom Alexis
    • Tizé Koda Joël
    • Sébastien Vondou Vondou
    • Roger Djouldé Darman
    Revue Sahélienne d'Ingénierie et Sciences Appliquées (RSIA), ENSPM de l’Université de Maroua , 2022, 1 (1), pp.71 -75 . <div><p>Combustibles briquettes are energetics resources, which could be use to substitute other types of energy. Optimization of energetic efficiency of combustible briquette lead us to made it so that to contribute to thrift wood resources and local sustainable development. Valorization of dry dead leaves of Azadirachta indica associated to dry stems of Sorghum sp. upon to made combustibles briquettes is the object of this work. By using mechanics process, production of combustibles conducts us to show their physicals characteristics where it average density is 0.34±0.09 and average ratio surface/volume is 22.68±3.97cm-1. Chemicals characteristics permit us to identify 7.68±0.32% as moisture content when the fixed carbon content average is 91.00±4.83%. Inflammability test demonstrate that maximal duration of inflammation is 0.19± 0.02 minutes with time limit of 0.09± 0.02 minutes. Combustion test show that combustion duration average is 19.03±7.07 minutes with 66,50±9,18% as loss mass of combustible briquette.</p></div>
  • An Optimized Buffer for Repeatable Multicolor STORM
    • Abdelsayed Vaky
    • Boukhatem Hadjer
    • Olivier Nicolas
    ACS photonics, American Chemical Society , 2022 . (10.1021/acsphotonics.2c01249)
    DOI : 10.1021/acsphotonics.2c01249
  • Early processes in heme-based CO-sensing proteins
    • Vos Marten H
    • Salman Mayla
    • Liebl Ursula
    Frontiers in Molecular Biosciences, Frontiers Media , 2022, 9, pp.1046412 . Carbon monoxide has been recognized relatively recently as signaling molecule, and only very few dedicated natural CO sensor proteins have been identified so far. These include in particular heme-based transcription factors: the bacterial sensor proteins CooA and RcoM. In these 6-coordinated systems, exchange between an internal protein residue and CO as a heme ligand in the sensor domain affects the properties of the DNA-binding domain. Using light to dissociate heme-ligand bonds can in principle initiate this switching process. We review the efforts to use this method to investigate early processes in ligand switching and signaling, with an emphasis on the CO-"trapping" properties of the heme cavity. These features are unusual for most heme proteins, but common for heme-based CO sensors. (10.3389/fmolb.2022.1046412)
    DOI : 10.3389/fmolb.2022.1046412
  • Inline amplification of mid-infrared intrapulse difference frequency generation
    • Bournet Q.
    • Jonusas M.
    • Zheng A.
    • Guichard F.
    • Natile M.
    • Zaouter Y.
    • Joffre M.
    • Bonvalet A.
    • Druon F.
    • Hanna Marc
    • Georges P.
    Optics Letters, Optical Society of America - OSA Publishing , 2022, 47 (19), pp.4885 . We demonstrate an ultrafast mid-infrared source architecture that implements both intrapulse difference frequency generation (iDFG) and further optical parametric amplification (OPA), in an all-inline configuration. The source is driven by a nonlinearly compressed high-energy Yb-doped-fiber amplifier delivering 7.4 fs pulses at a central wavelength of 1030 nm, at a repetition rate of 250 kHz. It delivers 1 µJ, 73 fs pulses at a central wavelength of 8 µm, tunable over more than one octave. By enrolling all the pump photons in the iDFG process and recycling the long wavelength pump photons amplified in the iDFG in the subsequent OPA, we obtain an unprecedented overall optical efficiency of 2%. These performances, combining high energy and repetition rate in a very simple all-inline setup, make this technique ideally suited for a growing number of applications, such as high harmonic generation in solids or two-dimensional infrared spectroscopy experiments. (10.1364/OL.467792)
    DOI : 10.1364/OL.467792
  • hnRNPA1/UP1 Unfolds KRAS G-Quadruplexes and Feeds a Regulatory Axis Controlling Gene Expression
    • Ferino Annalisa
    • Marquevielle Julien
    • Choudhary Himanshi
    • Cinque Giorgio
    • Robert Coralie
    • Bourdoncle Anne
    • Picco Raffaella
    • Mergny Jean-Louis
    • Salgado Gilmar
    • Xodo Luigi
    ACS Omega, ACS Publications , 2021, 6 (49), pp.34092-34106 . (10.1021/acsomega.1c05538)
    DOI : 10.1021/acsomega.1c05538
  • Exploring Sequence Space to Design Controllable G-Quadruplex Topology Switches
    • Chen Jielin
    • Cheng Mingpan
    • Stadlbauer Petr
    • Šponer Jiří
    • Mergny Jean-Louis
    • Ju Huangxian
    • Zhou Jun
    CCS Chemistry, Chinese Chemical Society , 2021, pp.3232 - 3246 . As nonclassical nucleic acid structures, G-quadruplexes (G4s) not only play important roles in gene regulation and stability maintenance, but are also widely used in nanotechnology. Structural diversity is one of the main factors explaining the popularity of G4s, but a comprehensive and integrated study of different factors determining G4 structural versatility is currently lacking. Herein, starting from a common G4 sequence, (G 3 T) 3 G 3 , as the parent chain, and then taking advantage of G4 versatility, we present a variety of strategies to control G4 structure, based on the regulation of loop length and flanking sequences, cation (type and concentration), and molecular crowding. These strategies allow us to convert the G4 topology from parallel to hybrid, to antiparallel, and then back to parallel. Such structural diversity reveals the coding regulation ability of G4 structures, with potential applications in nanotechnology. (10.31635/ccschem.021.202101357)
    DOI : 10.31635/ccschem.021.202101357
  • The beginning and the end: flanking nucleotides induce a parallel G-quadruplex topology
    • Chen Jielin
    • Cheng Mingpan
    • Salgado Gilmar F
    • Stadlbauer Petr
    • Zhang Xiaobo
    • Amrane Samir
    • Guédin Aurore
    • He Fangni
    • Šponer Jiří
    • Ju Huangxian
    • Mergny Jean-Louis
    • Zhou Jun
    Nucleic Acids Research, Oxford University Press , 2021, 49 (16), pp.9548-9559 . Abstract Genomic sequences susceptible to form G-quadruplexes (G4s) are always flanked by other nucleotides, but G4 formation in vitro is generally studied with short synthetic DNA or RNA oligonucleotides, for which bases adjacent to the G4 core are often omitted. Herein, we systematically studied the effects of flanking nucleotides on structural polymorphism of 371 different oligodeoxynucleotides that adopt intramolecular G4 structures. We found out that the addition of nucleotides favors the formation of a parallel fold, defined as the ‘flanking effect’ in this work. This ‘flanking effect’ was more pronounced when nucleotides were added at the 5′-end, and depended on loop arrangement. NMR experiments and molecular dynamics simulations revealed that flanking sequences at the 5′-end abolish a strong syn-specific hydrogen bond commonly found in non-parallel conformations, thus favoring a parallel topology. These analyses pave a new way for more accurate prediction of DNA G4 folding in a physiological context. (10.1093/nar/gkab681)
    DOI : 10.1093/nar/gkab681