Articles

Fourier-transform coherent anti-Stokes Raman scattering microscopy.
- Ogilvie Jennifer P.
- Beaurepaire Emmanuel
- Alexandrou Antigoni
- Joffre Manuel
Optics Letters, Optical Society of America - OSA Publishing , 2006, 31 (4), pp.480-2 . We report a novel Fourier-transform-based implementation of coherent anti-Stokes Raman scattering (CARS) microscopy. The method employs a single femtosecond laser source and a Michelson interferometer to create two pulse replicas that are fed into a scanning multiphoton microscope. By varying the time delay between the pulses, we time-resolve the CARS signal, permitting easy removal of the nonresonant background while providing high resolution, spectrally resolved images of CARS modes over the laser bandwidth (approximately 1500 cm(-1)). We demonstrate the method by imaging polystyrene beads in solvent. (10.1364/OL.31.000480)
DOI : 10.1364/OL.31.000480
Insight into Framework Destruction in Ultramarine Pigments
- del Federico Eleonora
- Shöfberger Wolfgang
- Schelvis Johannes
- Kapetanaki Sofia
- Tyne Lindsey
- Jerschow Alexej
Inorganic Chemistry, American Chemical Society , 2006, 45 (3), pp.1270-1276 . (10.1021/ic050903z)
DOI : 10.1021/ic050903z
Use of coherent control for selective two-photon fluorescence microscopy in live organisms.
- Ogilvie Jennifer P.
- Débarre Delphine
- Solinas Xavier
- Martin Jean-Louis
- Beaurepaire Emmanuel
- Joffre Manuel
Optics Express, Optical Society of America - OSA Publishing , 2006, 14 (2), pp.759-766 . We demonstrate selective fluorescence We demonstrate selective fluorescence excitation of specific molecular species in live organisms by using coherent control of two-photon excitation. We have acquired quasi-simultaneous images in live fluorescently-labeled Drosophila embryos by rapid switching between appropriate pulse shapes. Linear combinations of these images demonstrate that a high degree of fluorophore selectivity is attainable through phase-shaping. Broadband phase-shaped excitation opens up new possibilities for single-laser, multiplex, in-vivo fluorescence microscopy. © 2006 Optical Society of America (10.1364/OPEX.14.000759)
DOI : 10.1364/OPEX.14.000759
Chiroptical effects in the second harmonic generation from collagens I and IV: applications in nonlinear microscopy
- Pena Ana-Maria
- Boulesteix Thierry
- Dartigalongue Thibault
- Strupler Mathias
- Beaurepaire Emmanuel
- Schanne-Klein Marie-Claire
Nonlinear optics, quantum optics, Old City Pub. , 2006, 35 (1-3), pp.235-240 . An emerging application of multiphoton microscopy is the observation of unstained intact biological tissues based on intrinsic sources of nonlinear signals. However, reliable biomedical imaging requires a thorough analysis of these endogenous signals. Looking at skin biopsies, we focused on 2-Photon Excited Fluorescence (2PEF) arising from cytokeratins in the epidermis, and second harmonic generation (SHG) from collagen fibers in the dermis. We determined the 2PEF excitation spectrum and action cross section of purified keratins from human epidermis, and obtained a good agreement with in situ measurements. In order to analyze the role of chirality and collagen type in SHG signal, we performed polarization-resolved surface SHG experiments on thin films of collagens I and IV molecules. We observed that collagen I and IV molecules exhibit comparable SHG signals, except for the chiral contributions which are absent for collagen IV and represent typically 50% of the signal for collagen I. We concluded that the large collagen I SHG efficiency is dominated by coherent effects due to the high density and quasi-crystalline order in collagen fibrils, whereas the lack of any alignment within the collagen IV molecules explains the absence of signal from this collagen type in SHG microscopy.
Role of distal arginine in early sensing intermediates in the heme domain of the oxygen sensor FixL
- Jasaitis Audrius
- Hola Klara
- Bouzhir-Sima Latifa
- Lambry Jean-Christophe
- Balland Véronique
- Vos Marten H.
- Liebl Ursula
Biochemistry, American Chemical Society , 2006, 45, pp.6018-6026 .
Role of Heme Iron Coordination and Protein Structure in the Dynamics and Geminate Rebinding of Nitric Oxide to H93G Myoglobin : Implications for NO-Sensors
- Négrerie Michel
- Kruglik Sergei
- Lambry Jean-Christophe
- Vos Marten H.
- Martin Jean-Louis
- Franzen Stefan
Journal of Biological Chemistry, American Society for Biochemistry and Molecular Biology , 2006, 281, pp.10389-10398 .
Functional implications of the propionate 7 Arginine 220 interaction in the FixLH oxygen sensor from Bradyrhizobium japonicum
- Balland Véronique
- Bouzhir-Sima Latifa
- Anxolabéhère-Mallart E.
- Boussac A.
- Vos Marten H.
- Liebl Ursula
- Mattioli T.
Biochemistry, American Chemical Society , 2006, 45, pp.2072-2084 .
Terahertz achromatic quarter-wave plate
- Masson Jean-Baptiste
- Gallot Guilhem
Optics Letters, Optical Society of America - OSA Publishing , 2006, 31 (2), pp.265 . Phase retardera usually present a strong frequency dependence. We discuss the design and characterization of a terahertz achromatic quarter-wave plate. This wave plate is made from six birefringent quartz plates precisely designed and stacked together. Phase retardation has been measured over the whole terahertz range by terahertz polarimetry. This achromatic wave plate demonstrates a huge frequency bandwidth (?max/?min ˜ 7), and therefore can be applied to terahertz time domain spectroscopy and polarimetry. Cop. 2006 Optical Society of America. (10.1364/OL.31.000265)
DOI : 10.1364/OL.31.000265
Observer les neurones grâce aux ondes térahertz
- Gallot Guilhem
La Recherche, Sciences et avenir , 2006, 397, pp.26 . Des chercheurs de l'École polytechnique ont développé un dispositif d'imagerie des neurones, fondée sur l'utilisation d'ondes térahertz [1]. Ils observent ainsi les mouvements d'ions et d'eau à l'intérieur et à proximité des neurones.
Evaluation of 23S rRNA PCR primers for use in phylogenetic studies of bacterial diversity
- Hunt D.E.
- Klepac-Ceraj V.
- Acinas S.G.
- Bertilsson S.
- Gautier Christian
- Polz M.F.
Applied and Environmental Microbiology, American Society for Microbiology , 2006, 72 (3), pp.2221 . The availability of a diverse set of 23S rRNA gene sequences enabled evaluation of the specificity of 39 previously published and 4 newly designed primers specific for bacteria. An extensive clone library constructed using an optimized primer pair resulted in similar gene richness but slightly differing coverage of some phylogenetic groups, compared to a 16S rRNA gene library from the same environmental sample. Copyright Cop. 2006, American Society for Microbiology. All Rights Reserved. (10.1128/AEM.72.3.2221-2225.2006)
DOI : 10.1128/AEM.72.3.2221-2225.2006
Micrometer scale ex vivo multiphoton imaging of unstained arterial wall structure
- Boulesteix Thierry
- Pena Ana-Maria
- Pagès Nicole
- Godeau G.
- Sauviat Martin-Pierre
- Beaurepaire Emmanuel
- Schanne-Klein Marie-Claire
Cytometry Part A, Wiley , 2006, 69A (1), pp.20-26 . We characterize the application of multiphoton microscopy to the observation of the extracellular matrix of fresh unstained vessels. Combined two-photon-excited fluorescence (2PEF) and second harmonic generation (SHG) imaging of large arteries reveals the architecture of elastin and collagen fibers in the vessel wall with remarkable specificity. We present elastin/collagen imaging in unstained rat vessels at both micrometer and whole vessel scales, and we characterize the optical properties of rat carotid artery and aorta walls. We apply this method to evidence deleterious effects of residual doses of a pesticide on the vessel wall. This study illustrates the potential of 2PEF/SHG microscopy for pharmacological studies in unlabeled arteries. © 2005 Wiley-Liss, Inc. (10.1002/cyto.a.20196)
DOI : 10.1002/cyto.a.20196
A filtering procedure for systematic removal of pump-perturbed polarization artifacts
- Polack Thomas
Optics Express, Optical Society of America - OSA Publishing , 2006, 14, pp.5823 .
Dynamics of NO rebinding to the heme domain of NO synthase-like proteins from bacterial pathogens
- Gautier Clément
- Mikula Ivan
- Nioche P.
- Martasek P.
- Raman C.
- Slama-Schwok Anny
Nitric Oxide , 2006, à paraître .
Conformation of the c552:aa3 electron transfer complex in Paracoccus denitrificans studied by EPR on oriented samples
- Lipowski Gérard
- Liebl Ursula
- Guigliarelli Bruno
- Nitschke Wolfgang
- Schoepp-Cothenet Barbara
FEBS Letters, Wiley , 2006, 580 (25), pp.5988 . The EPR spectral parameters of aa3 oxidase and cyt c552 from Paracoccus denitrificans were studied in purified oxidase and enriched cyt c552. The orientation of the g-tensors of hemes a and c552 were determined on partially ordered membranes, enriched cyt c552 and a c552:aa3 subcomplex. The known correlation of g-tensor to molecular axes in histidine/methionine ligated hemes permits us to position cyt c552 with respect to the parent membrane. Taken together with previous data on the interaction surface between aa3 oxidase and cyt c552, these results allow us to arrive at a single conformation for the c552:aa3 electron transfer complex. Cop. 2006 Federation of European Biochemical Societies. (10.1016/j.febslet.2006.09.038)
DOI : 10.1016/j.febslet.2006.09.038
Emission properties and applications of nanostructured luminescent oxide nanoparticles
- Giaume D.
- Buissette V.
- Lahlil K.
- Gacoin T.
- Boilot J.-P.
- Casanova Didier
- Beaurepaire Emmanuel
- Sauviat Martin-Pierre
- Alexandrou Antigoni
Progress in Solid State Chemistry, Elsevier , 2006, 33 (2-4), pp.99 . Rare earth doped oxide materials are well known for their numerous applications in light emitting devices. An interesting issue is to study the emission properties of nanoparticles, with the aim to understand the influence of small size and surface effects on the emission processes. These particles could furthermore be used in new applications such as the elaboration of transparent emitting devices or new biological labels. The work presented here concerns highly luminescent rare earth doped yttrium vanadates (YVO4:Eu) and lanthanum phosphate LaPO4:Ce,Tb*xH2O nanoparticles. Simple aqueous colloidal syntheses are used for the elaboration of concentrated colloids based on the progressive decomposition of polymeric precursors at moderate temperature (60-90 °C). Both types of particles exhibit strong emission (quantum yields of 25% and 45% for vanadates and phosphates, respectively), but significantly lower than that for the equivalent bulk materials. The alteration of the emission processes is discussed in terms of surface quenching effects. Improvements are obtained through the elaboration of core/shell nanostructures. Surface derivatization has been achieved through the controlled growth of an organically modified silica shell using a functionalized silane precursor. Two examples are given concerning the applications of those particles. The first one is the elaboration of transparent and highly luminescent thin films, obtained by the dispersion of the functionalized particles in a sol-gel silica matrix. The other one is the use of guanidine functionalized particles as biological labels for the single particle detection of sodium channels in cardiac cells. (10.1016/j.progsolidstchem.2005.11.041)
DOI : 10.1016/j.progsolidstchem.2005.11.041
Ionic contrast terahertz time resolved imaging of frog auricular heart muscle electrical activity
- Masson Jean-Baptiste
- Sauviat Martin-Pierre
- Gallot Guilhem
Applied Physics Letters, American Institute of Physics , 2006, 89 (15), pp.153904 . The authors demonstrate the direct, noninvasive and time resolved imaging of functional frog auricular fibers by ionic contrast terahertz (ICT) near field microscopy. This technique provides quantitative, time-dependent measurement of ionic flow during auricular muscle electrical activity, and opens the way of direct noninvasive imaging of cardiac activity under stimulation. ICT microscopy technique was associated with full three-dimensional simulation enabling to measure precisely the fiber sizes. This technique coupled to waveguide technology should provide the grounds to development of advanced in vivo ion flux measurement in mammalian hearts, allowing the prediction of heart attack from change in K+ fluxes. Cop. 2006 American Institute of Physics. (10.1063/1.2360931)
DOI : 10.1063/1.2360931
Microscopies multiharmoniques pour l'imagerie structurale de tissus intacts [Second- and third-harmonic generation microscopies for the structural imaging of intact tissues]
- Débarre Delphine
- Pena Ana-Maria
- Supatto Willy
- Boulesteix Thierry
- Strupler Mathias
- Martin Jean-Louis
- Sauviat Martin-Pierre
- Schanne-Klein Marie-Claire
- Beaurepaire Emmanuel
Médecine/Sciences, EDP Sciences , 2006, 22 (10), pp.845 . Depuis son introduction en 1990, la microscopie de fluorescence excitée à deux photons (Fluo-2P) s'est peu à peu imposée comme une méthode incontournable d'imagerie de tissus intacts à l'échelle sub-cellulaire. En effet, la caractéristique la plus remarquable de la microscopie multiphotonique est de maintenir une résolution tridimensionnelle micrométrique lors de l'observation en profondeur d'un milieu optiquement diffusant. Combinée aux technologies de protéines-fusion (type GFP), cette approche est aujourd'hui utilisée dans de nombreux domaines, notamment en neurophysiologie. Un autre attrait de ce type d'imagerie réside dans l'utilisation possible d'autres phénomènes optiques non linéaires (c'est-à-dire impliquant l'interaction simultanée de plusieurs photons avec une molécule observée) comme source de contraste. Ainsi, les microscopies par génération de second harmonique (GSH) et par génération de troisième harmonique (GTH) permettent également d'observer des milieux complexes et fournissent des informations complémentaires par rapport à l'imagerie de fluorescence. Certaines structures cellulaires ou tissulaires fournissent, en effet, ce type de réponse optique sans nécessiter de marquage exogène. La microscopie GSH permet, par exemple, de détecter le collagène fibrillaire et la microscopie GTH permet d'observer sans marquage le développement embryonnaire de petits organismes. One principal advantage of multiphoton excitation microscopy is that it preserves its three-dimensional micrometer resolution when imaging inside light-scattering samples. For that reason two-photon-excited fluorescence microscopy has become an invaluable tool for cellular imaging in intact tissue, with applications in many fields of physiology. This success has driven increasing interest in other forms of nonlinear microscopy that can provide additional information on cells and tissues, such as second- (SHG) and third- (THG) harmonic generation microscopies. In recent years, significant progress has been made in understanding the contrast mechanisms of these recent methodologies, and high-resolution imaging based on intrinsic sources of signal has been demonstrated in cells and tissues. Harmonic generation exhibits structural rather than chemical specificity and can be obtained from a variety of non-fluorescent samples. SHG is observed specifically in dense, non-centrosymmetric arrangements of polarizable molecules, such as collagen fibrils, myofilaments, and polarized microtubule bundles. SHG imaging is therefore emerging as a novel approach for studying processes such as the physiopathological remodelling of the collagen matrix and myofibrillogenesis in intact tissue. THG does not require a non-centrosymmetric system; however no signal can be obtained from a homogeneous medium. THG imaging therefore provides maps of sub-micrometer heterogeneities (interfaces, inclusions) in unstained samples, and can be used as a general purpose structural imaging tool. Recent studies showed that this technique can be used to image embryo development in small organisms and to characterize the accumulation of large lipid bodies in specialized cells. SHG and THG microscopy both rely on femtosecond laser technology and are easily combined with two-photon microscopy. (10.1051/medsci/20062210845)
DOI : 10.1051/medsci/20062210845
Ionic contrast terahertz near field imaging of axonal water fluxes
- Masson Jean-Baptiste
- Sauviat Martin-Pierre
- Martin Jean-Louis
- Gallot Guilhem
Proceedings of the National Academy of Sciences of the United States of America, National Academy of Sciences , 2006, 103 (13), pp.4808-4812 .
Parametric cascade downconverter for intense ultrafast mid-infrared generation beyond the Manley-Rowe limit
- Fraser James M.
- Ventalon Cathie
Applied optics, Optical Society of America , 2006, 45 (17), pp.4109-4113 . We propose a scheme to generate intense, ultrafast mid-infrared pulses with conversion efficiencies exceeding the upper bound for single-stage difference-frequency mixing as predicted by the Manley-Rowe relations. Finite-element fast Fourier transform simulations of the mixing process show that the parametric cascade downconverter generates 1.7 times more photons (at 10 μm ) than in the initial pump pulse (center wavelength of 1.48 μm , duration of 130 fs , and pulse energy of 50 μJ ), with negligible pulse spatial and temporal distortion. © 2006 Optical Society of America (10.1364/AO.45.004109)
DOI : 10.1364/AO.45.004109
Coupling between surface plasmons in subwavelength hole arrays
- Masson Jean-Baptiste
- Gallot Guilhem
Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society , 2006, 73, pp.121401 .
Measuring the dynamics of circular dichroism in a pump-probe experiment with a Babinet-Soleil compensator
- Niezborala Claire
- Hache François
Journal of the Optical Society of America B, Optical Society of America , 2006, 23 (11), pp.2418 . Circular dichroism contains rich information on the conformation of molecules and, in particular, of biomolecules, and measuring its variation in a pump-probe experiment is very promising but also very challenging. We propose a new technique to measure pump-induced variation of the circular dichroism, which is based on the measurement of the probe ellipticity and its variation with the pump. This technique has the advantage that it does not require modulation of the probe polarization, which allows modulation of the pump intensity. We show theoretically and demonstrate experimentally that this technique is very sensitive and user friendly. We also show that it can be used to measure pump-induced change in the optical rotation, allowing for a complete characterization of pump-induced optical activity. Cop. 2006 Optical Society of America. (10.1364/JOSAB.23.002418)
DOI : 10.1364/JOSAB.23.002418
Hydrophobic distal pocket affects NO-heme geminate recombination dynamics in dehaloperoxidase and H64V myoglobin
- Franzen S.
- Jasaitis Audrius
- Belyea J.
- Brewer S.
- Casey Romain
- Macfarlane A.
- Martin Jean-Louis
- Stanley R.
- Vos Marten H.
Journal of Physical Chemistry B, American Chemical Society , 2006, 110 (29), pp.14483 . The recombination dynamics of NO with dehaloperoxidase ( DHP) from Amphitrite ornata following photolysis were measured by femtosecond time- resolved absorption spectroscopy. Singular value decomposition ( SVD) analysis reveals two important basis spectra. The first SVD basis spectrum reports on the population of photolyzed NO molecules and has the appearance of the equilibrium difference spectrum between the deoxy and NO forms of DHP. The first basis time course has two kinetic components with time constants of tau(11) approximate to 9 ps and tau(12) approximate to 50 ps that correspond to geminate recombination. The fast geminate process tau(11) arises from a contact pair with the heme iron in a bound state with S) 3/2 spin. The slow geminate process tau(12) corresponds to the recombination from a more remote docking site > 3 angstrom from the heme iron with the greater barrier corresponding to a S) 5/ 2 spin state. The second SVD basis spectrum represents a time- dependent Soret band shift indicative of heme photophysical processes and protein relaxation with time constants of tau(21) approximate to 3 ps and tau(22) approximate to 17 ps, respectively. A comparison between the more rapid rate constant of the slow geminate phase in DHP- NO and horse heart myoglobin ( HHMbNO) or sperm whale myoglobin ( SWMbNO) suggests that protein interactions with photolyzed NO are weaker in DHP than in the wild- type MbNOs, consistent with the hydrophobic distal pocket of DHP. The slower protein relaxation rate tau(22) in DHP- NO relative to HHMbNO implies less effective trapping in the docking site of the distal pocket and is consistent with a greater yield for the fast geminate process. The trends observed for DHP- NO also hold for the H64V mutant of SWMb ( H64V MbNO), consistent with a more hydrophobic distal pocket for that protein as well. We examine the influence of solution viscosity on NO recombination by varying the glycerol content in the range from 0% to 90% ( v/ v). The dominant effect of increasing viscosity is the increase of the rate of the slow geminate process, tau(12), coupled with a population decrease of the slow geminate component. Both phenomena are similar to the effect of viscosity on wild- type Mb due to slowing of protein relaxation resulting from an increased solution viscosity and protein surface dehydration. (10.1021/jp056790m)
DOI : 10.1021/jp056790m
Photoinduced electron transfer from a novel nanotrigger addressed to the NADPH site within the endothelial NO-synthase to the flavin moieties of the protein
- Beaumont Edward
- Robin Anne-Claire
- Berka Vladimir
- Tsai Ah-Lim
- Blanchard-Desce Mireille
- Lambry Jean-Christophe
- Slama-Schwok Anny
Nitric Oxide: Biology and Chemistry, Elsevier , 2006, 14 (4), pp.14-15 . We developed a new selective molecular tool to trigger enzymatic activity in a synchronous manner and monitor the sequence of the kinetic events by ultra-fast transient spectroscopy. Our approach is based on a synthetic nanotrigger addressing a selected site within proteins, namely the conserved NADPH binding site common to many enzymes involved in bioreductive processes [1]. The nanotrigger combines a "docking" subunit responsible for the recognition of NADPH sites within proteins and a "chromophoric" subunit responsive to light excitation and able to transfer electrons to the flavin moieties of proteins. We present the first spectroscopic data on such a nanotrigger [1] in the presence of the reductase domain of the endothelial nitric oxide synthase eNOSred. (10.1016/j.niox.2006.04.050)
DOI : 10.1016/j.niox.2006.04.050
Nouvelle approche des fibroses par microscopie multiphotonique avec génération de second harmonique [New approach of fibrosis by multiphoton microscopy with second harmonic generation]
- Hernest Monica
- Pena Ana-Maria
- Strupler Mathias
- Beaurepaire Emmanuel
- Martin Jean-Louis
- Schanne-Klein Marie-Claire
- Tharaux Pierre-Louis
Médecine/Sciences, EDP Sciences , 2006, 22 (10), pp.820-821 . La fibrose est une réponse adaptative pathologique qui détruit non spécifiquement les tissus. Il s'agit d'un processus universel de réparation des tissus qui survient en réaction à de nombreux types d'agressions telles les contraintes mécaniques, les brûlures, les radiations ionisantes, l'ischémie, l'inflammation. Ces agressions concourent de manière intriquée à la physiopathologie des maladies infectieuses, tumorales ou auto-immunes, de l'hypertension artérielle et des maladies cardio-vasculaires. Le terme de fibrose décrit précisément l'accumulation nouvelle de protéines de la matrice extra-cellulaire selon un arrangement spatial fibrillaire caractéristique. Il s'agit essentiellement de molécules de collagènes de type I et III (voire de type II, V ou XI) synthétisées sous forme de triples hélices elles-mêmes assemblées en fibrilles par les cellules fibroblastiques. L'apparition des collagènes fibrillaires marque un changement qualitatif et quantitatif de composition des collagènes des tissus. Réciproquement, ces changements de la matrice extracellulaire influencent le phénotype des cellules qui y résident. Ainsi dans le rein normal, le collagène de type I n'existe que dans l'adventice artériel. Son apparition au sein des autres structures de cet organe marque une fibrose tubulo-interstitielle qui constitue le meilleur marqueur pronostic défavorable d'une évolution vers l'insuffisance rénale terminale, et ce quelle que soit la maladie causale. Ainsi, comme lors des fibroses compliquant les hépatopathies et les pneumopathies chroniques, les séquelles de brûlures ou d'abrasions cutanées-muqueuses ou encore le remodelage cardiaque et vasculaire, le réarrangement de la géométrie de la matrice extracellulaire altère l'organisation fonctionnelle du tissu considéré. De ce fait, ce processus de réparation a des effets fonctionnels délétères qui constituent un enjeu médical majeur. Les fibrilles de collagène ont des capacités d'auto-assemblage qui sont aussi catalysées et stabilisées ou au contraire empêchées par les enzymes de la matrice extracellulaire. Le développement de la fibrose ou sa régression dépend donc ainsi du bilan des équilibres biologiques de ces mécanismes. Il est donc crucial de caractériser les changements extracellulaires et cellulaires qui font du restutio ad integrum de l'architecture et de la fonction tissulaire un défi biomédical. (10.1051/medsci/20062210820)
DOI : 10.1051/medsci/20062210820
Role of the middle residue in the triple tryptophan electron transfer chain of DNA photolyase: ultrafast spectroscopy of a Trp→Phe mutant
- Lukacs Andras
- Eker A.P.M.
- Byrdin M.
- Villette Sandrine
- Pan J.
- Brettel K.
- Vos Marten H.
Journal of Physical Chemistry B, American Chemical Society , 2006, 110 (32), pp.15654-15658 .