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Joli N, Concia L, Mocaer K, Guterman J, Laude J, Guerin S, Sciandra T, Bruyant F, Ait-Mohamed O, Beguin M, Forget MH, Bourbousse C, Lacour T, Bailleul B, Nef C, Savoie M, Tremblay JE, Campbell DA, Lavaud J, Schwab Y, Babin M, Bowler C. Hypometabolism to survive the long polar night and subsequent successful return to light in the diatom Fragilariopsis cylindrus. New Phytol 2024; 241:2193-2208. [PMID: 38095198 DOI: 10.1111/nph.19387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2023] [Accepted: 10/17/2023] [Indexed: 02/09/2024]
Abstract
Diatoms, the main eukaryotic phytoplankton of the polar marine regions, are essential for the maintenance of food chains specific to Arctic and Antarctic ecosystems, and are experiencing major disturbances under current climate change. As such, it is fundamental to understand the physiological mechanisms and associated molecular basis of their endurance during the long polar night. Here, using the polar diatom Fragilariopsis cylindrus, we report an integrative analysis combining transcriptomic, microscopic and biochemical approaches to shed light on the strategies used to survive the polar night. We reveal that in prolonged darkness, diatom cells enter a state of quiescence with reduced metabolic and transcriptional activity, during which no cell division occurs. We propose that minimal energy is provided by respiration and degradation of protein, carbohydrate and lipid stores and that homeostasis is maintained by autophagy in prolonged darkness. We also report internal structural changes that manifest the morphological acclimation of cells to darkness, including the appearance of a large vacuole. Our results further show that immediately following a return to light, diatom cells are able to use photoprotective mechanisms and rapidly resume photosynthesis, demonstrating the remarkable robustness of polar diatoms to prolonged darkness at low temperature.
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Affiliation(s)
- Nathalie Joli
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Lorenzo Concia
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Karel Mocaer
- Cell Biology and Biophysics Unit, European Molecular Biology Laboratory (EMBL) & Collaboration for Joint PhD Degree between the European Molecular Biology Laboratory and the Heidelberg University, Faculty of Biosciences, 69117, Heidelberg, Germany
| | - Julie Guterman
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Juliette Laude
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Sebastien Guerin
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Theo Sciandra
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Flavienne Bruyant
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Ouardia Ait-Mohamed
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Marine Beguin
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Marie-Helene Forget
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Clara Bourbousse
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Thomas Lacour
- Laboratoire PHYSiologie des micro ALGues (PDG-ODE-PHYTOX-PHYSALG), Centre Atlantique, 44 311, Nantes, France
| | - Benjamin Bailleul
- Laboratory of Chloroplast Biology and Light Sensing in Microalgae, Institut de Biologie Physico Chimique, CNRS, Sorbonne Université, Paris, 75005, France
| | - Charlotte Nef
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
| | - Mireille Savoie
- Département de Biologie, Université Laval, Québec, QC, G1V 0A6, Canada
| | | | | | - Johann Lavaud
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
- UMR 6539 LEMAR-Laboratory of Environmental Marine Sciences, CNRS/Univ Brest/Ifremer/IRD, IUEM-Institut Européen de la Mer, Technopôle Brest-Iroise, rue Dumont d'Urville, 29280, Plouzané, France
| | - Yannick Schwab
- Cell Biology and Biophysics Unit and Electron Microscopy Core Facility, European Molecular Biology Laboratory (EMBL), 69117, Heidelberg, Germany
| | - Marcel Babin
- Takuvik International Research Laboratory, Université Laval (Canada) & CNRS (France), Département de Biologie and Québec-Océan, Université Laval, Québec, QC, G1V 0A6, Canada
| | - Chris Bowler
- Institut de Biologie de l'École Normale Supérieure (IBENS), École Normale Supérieure, CNRS, INSERM, PSL Université Paris, 75005, Paris, France
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2
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Thuillier S, Viola S, Lockett-Walters B, Nay B, Bailleul B, Baudouin E. Mode-of-action of the natural herbicide radulanin A as an inhibitor of photosystem II. Pest Manag Sci 2024; 80:156-165. [PMID: 37293747 DOI: 10.1002/ps.7609] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Revised: 05/24/2023] [Accepted: 06/09/2023] [Indexed: 06/10/2023]
Abstract
BACKGROUND Radulanin A is a natural 2,5-dihydrobenzoxepin synthesized by several liverworts of the Radula genus. Breakthroughs in the total synthesis of radulanin A paved the way for the discovery of its phytotoxic activity. Nevertheless, its mode-of-action (MoA) has remained unknown so far and thus was investigated, in Arabidopsis thaliana. RESULTS Radulanin A phytotoxicity was associated with cell death and partially depended on light exposure. Photosynthesis measurements based on chlorophyll-a fluorescence evidenced that radulanin A and a Radula chromene inhibited photosynthetic electron transport with IC50 of 95 and 100 μm, respectively. We established a strong correlation between inhibition of photosynthesis and phytotoxicity for a range of radulanin A analogs. Based on these data, we also determined that radulanin A phytotoxicity was abolished when the hydroxyl group was modified, and was modulated by the presence of the heterocycle and its aliphatic chain. Thermoluminescence studies highlighted that radulanin A targeted the QB site of the Photosystem II (PSII) with a similar MoA as 3-(3,4-dichloropheny)-1,1-dimethylurea (DCMU). CONCLUSION We establish that radulanin A targets PSII, expanding QB sites inhibitors to bibenzyl compounds. The identification of an easy-to-synthesize analog of radulanin A with similar MoA and efficiency might be useful for future herbicide development. © 2023 Society of Chemical Industry.
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Affiliation(s)
- Simon Thuillier
- Laboratoire de Biologie du Développement, Institut de Biologie Paris Seine, Sorbonne Université, CNRS, Paris, France
- Laboratoire de Synthèse Organique, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
| | - Stefania Viola
- Department of Life Sciences, Imperial College-South Kensington Campus, London, UK
| | - Bruce Lockett-Walters
- Laboratoire de Synthèse Organique, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
| | - Bastien Nay
- Laboratoire de Synthèse Organique, Ecole Polytechnique, CNRS, Institut Polytechnique de Paris, Palaiseau, France
| | - Benjamin Bailleul
- Chloroplast Biology and Light-sensing in Microalgae-UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France
| | - Emmanuel Baudouin
- Laboratoire de Biologie du Développement, Institut de Biologie Paris Seine, Sorbonne Université, CNRS, Paris, France
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3
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Falciatore A, Bailleul B, Boulouis A, Bouly JP, Bujaldon S, Cheminant-Navarro S, Choquet Y, de Vitry C, Eberhard S, Jaubert M, Kuras R, Lafontaine I, Landier S, Selles J, Vallon O, Wostrikoff K. Light-driven processes: key players of the functional biodiversity in microalgae. C R Biol 2022; 345:15-38. [PMID: 36847462 DOI: 10.5802/crbiol.80] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2022] [Accepted: 07/11/2022] [Indexed: 11/24/2022]
Abstract
Microalgae are prominent aquatic organisms, responsible for about half of the photosynthetic activity on Earth. Over the past two decades, breakthroughs in genomics and ecosystem biology, as well as the development of genetic resources in model species, have redrawn the boundaries of our knowledge on the relevance of these microbes in global ecosystems. However, considering their vast biodiversity and complex evolutionary history, our comprehension of algal biology remains limited. As algae rely on light, both as their main source of energy and for information about their environment, we focus here on photosynthesis, photoperception, and chloroplast biogenesis in the green alga Chlamydomonas reinhardtii and marine diatoms. We describe how the studies of light-driven processes are key to assessing functional biodiversity in evolutionary distant microalgae. We also emphasize that integration of laboratory and environmental studies, and dialogues between different scientific communities are both timely and essential to understand the life of phototrophs in complex ecosystems and to properly assess the consequences of environmental changes on aquatic environments globally.
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Seydoux C, Storti M, Giovagnetti V, Matuszyńska A, Guglielmino E, Zhao X, Giustini C, Pan Y, Blommaert L, Angulo J, Ruban AV, Hu H, Bailleul B, Courtois F, Allorent G, Finazzi G. Impaired photoprotection in Phaeodactylum tricornutum KEA3 mutants reveals the proton regulatory circuit of diatoms light acclimation. New Phytol 2022; 234:578-591. [PMID: 35092009 PMCID: PMC9306478 DOI: 10.1111/nph.18003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Accepted: 01/16/2022] [Indexed: 06/14/2023]
Abstract
Diatoms are successful phytoplankton clades able to acclimate to changing environmental conditions, including e.g. variable light intensity. Diatoms are outstanding at dissipating light energy exceeding the maximum photosynthetic electron transfer (PET) capacity via the nonphotochemical quenching (NPQ) process. While the molecular effectors of NPQ as well as the involvement of the proton motive force (PMF) in its regulation are known, the regulators of the PET/PMF relationship remain unidentified in diatoms. We generated mutants of the H+ /K+ antiporter KEA3 in the model diatom Phaeodactylum tricornutum. Loss of KEA3 activity affects the PET/PMF coupling and NPQ responses at the onset of illumination, during transients and in steady-state conditions. Thus, this antiporter is a main regulator of the PET/PMF coupling. Consistent with this conclusion, a parsimonious model including only two free components, KEA3 and the diadinoxanthin de-epoxidase, describes most of the feedback loops between PET and NPQ. This simple regulatory system allows for efficient responses to fast (minutes) or slow (e.g. diel) changes in light environment, thanks to the presence of a regulatory calcium ion (Ca2+ )-binding domain in KEA3 modulating its activity. This circuit is likely tuned by the NPQ-effector proteins, LHCXs, providing diatoms with the required flexibility to thrive in different ocean provinces.
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Affiliation(s)
- Claire Seydoux
- CNRSCEAINRAEIRIGLPCVUniversité Grenoble AlpesGrenoble38000France
| | - Mattia Storti
- CNRSCEAINRAEIRIGLPCVUniversité Grenoble AlpesGrenoble38000France
| | - Vasco Giovagnetti
- Departement of BiochemistryQueen Mary University of LondonMile End RoadLondonE14NSUK
| | - Anna Matuszyńska
- Computational Life ScienceDepartment of BiologyRWTH Aachen UniversityWorringer Weg 1Aachen52074Germany
| | | | - Xue Zhao
- CNRSCEAINRAEIRIGLPCVUniversité Grenoble AlpesGrenoble38000France
| | - Cécile Giustini
- CNRSCEAINRAEIRIGLPCVUniversité Grenoble AlpesGrenoble38000France
| | - Yufang Pan
- Key Laboratory of Algal BiologyInstitute of HydrobiologyChinese Academy of SciencesWuhan430072China
| | - Lander Blommaert
- Laboratory of Chloroplast Biology and Light Sensing in MicroalgaeInstitut de Biologie Physico ChimiqueCNRSSorbonne UniversitéParis75005France
| | - Jhoanell Angulo
- CNRSCEAINRAEIRIGLPCVUniversité Grenoble AlpesGrenoble38000France
| | - Alexander V. Ruban
- Departement of BiochemistryQueen Mary University of LondonMile End RoadLondonE14NSUK
| | - Hanhua Hu
- Key Laboratory of Algal BiologyInstitute of HydrobiologyChinese Academy of SciencesWuhan430072China
| | - Benjamin Bailleul
- Laboratory of Chloroplast Biology and Light Sensing in MicroalgaeInstitut de Biologie Physico ChimiqueCNRSSorbonne UniversitéParis75005France
| | | | | | - Giovanni Finazzi
- CNRSCEAINRAEIRIGLPCVUniversité Grenoble AlpesGrenoble38000France
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Sayegh A, Perego LA, Arderiu Romero M, Escudero L, Delacotte J, Guille‐Collignon M, Grimaud L, Bailleul B, Lemaître F. Finding Adapted Quinones for Harvesting Electrons from Photosynthetic Algae Suspensions. ChemElectroChem 2021. [DOI: 10.1002/celc.202100757] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Adnan Sayegh
- PASTEUR Département de Chimie Ecole Normale Supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
| | - Luca A. Perego
- Laboratoire des biomolécules (LBM) Département de chimie Sorbonne Université École normale supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
| | - Marc Arderiu Romero
- PASTEUR Département de Chimie Ecole Normale Supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
- Laboratory of Membrane and Molecular Physiology at IBPC UMR 7141 CNRS/Sorbonne Université 13 rue Pierre et Marie Curie 75005 Paris France
| | - Louis Escudero
- PASTEUR Département de Chimie Ecole Normale Supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
| | - Jérôme Delacotte
- PASTEUR Département de Chimie Ecole Normale Supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
| | - Manon Guille‐Collignon
- PASTEUR Département de Chimie Ecole Normale Supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
| | - Laurence Grimaud
- Laboratoire des biomolécules (LBM) Département de chimie Sorbonne Université École normale supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
| | - Benjamin Bailleul
- Laboratory of Membrane and Molecular Physiology at IBPC UMR 7141 CNRS/Sorbonne Université 13 rue Pierre et Marie Curie 75005 Paris France
| | - Frédéric Lemaître
- PASTEUR Département de Chimie Ecole Normale Supérieure PSL University, Sorbonne Université CNRS, 75005 Paris France
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Blommaert L, Chafai L, Bailleul B. The fine-tuning of NPQ in diatoms relies on the regulation of both xanthophyll cycle enzymes. Sci Rep 2021; 11:12750. [PMID: 34140542 PMCID: PMC8211711 DOI: 10.1038/s41598-021-91483-x] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Accepted: 05/05/2021] [Indexed: 11/09/2022] Open
Abstract
Diatoms possess an efficient mechanism to dissipate photons as heat in conditions of excess light, which is visualized as the Non-Photochemical Quenching of chlorophyll a fluorescence (NPQ). In most diatom species, NPQ is proportional to the concentration of the xanthophyll cycle pigment diatoxanthin formed from diadinoxanthin by the diadinoxanthin de-epoxidase enzyme. The reverse reaction is performed by the diatoxanthin epoxidase. Despite the xanthophyll cycle's central role in photoprotection, its regulation is not yet well understood. The proportionality between diatoxanthin and NPQ allowed us to calculate the activity of both xanthophyll cycle enzymes in the model diatom Phaeodactylum tricornutum from NPQ kinetics. From there, we explored the light-dependency of the activity of both enzymes. Our results demonstrate that a tight regulation of both enzymes is key to fine-tune NPQ: (i) the rate constant of diadinoxanthin de-epoxidation is low under a light-limiting regime but increases as photosynthesis saturates, probably due to the thylakoidal proton gradient ΔpH (ii) the rate constant of diatoxanthin epoxidation exhibits an optimum under low light and decreases in the dark due to an insufficiency of the co-factor NADPH as well as in higher light through an as yet unresolved inhibition mechanism, that is unlikely to be related to the ΔpH. We observed that the suppression of NPQ by an uncoupler was due to an accelerated diatoxanthin epoxidation enzyme rather than to the usually hypothesized inhibition of the diadinoxanthin de-epoxidation enzyme.
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Affiliation(s)
- Lander Blommaert
- Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR 7141, Centre National de La Recherche Scientifique (CNRS), Sorbonne Université, Institut de Biologie Physico-Chimique, 75005, Paris, France. .,Department of Estuarine and Delta System, NIOZ Royal Netherlands Institute for Sea Research, PO Box 140, 4400 AC, Yerseke, The Netherlands.
| | - Lamia Chafai
- Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR 7141, Centre National de La Recherche Scientifique (CNRS), Sorbonne Université, Institut de Biologie Physico-Chimique, 75005, Paris, France
| | - Benjamin Bailleul
- Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR 7141, Centre National de La Recherche Scientifique (CNRS), Sorbonne Université, Institut de Biologie Physico-Chimique, 75005, Paris, France.
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7
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Buchert F, Bailleul B, Joliot P. Disentangling chloroplast ATP synthase regulation by proton motive force and thiol modulation in Arabidopsis leaves. Biochim Biophys Acta Bioenerg 2021; 1862:148434. [PMID: 33932368 DOI: 10.1016/j.bbabio.2021.148434] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Revised: 04/06/2021] [Accepted: 04/20/2021] [Indexed: 11/29/2022]
Abstract
The chloroplast ATP synthase (CF1Fo) contains a specific feature to the green lineage: a γ-subunit redox domain that contains a cysteine couple which interacts with the torque-transmitting βDELSEED-loop. This thiol modulation equips CF1Fo with an important environmental fine-tuning mechanism. In vitro, disulfide formation in the γ-redox domain slows down the activity of the CF1Fo at low transmembrane electrochemical proton gradient ( [Formula: see text] ), which agrees with its proposed role as chock based on recently solved structure. The γ-dithiol formation at the onset of light is crucial to maximize photosynthetic efficiency since it lowers the [Formula: see text] activation level for ATP synthesis in vitro. Here, we validate these findings in vivo by utilizing absorption spectroscopy in Arabidopsis thaliana. To do so, we monitored the [Formula: see text] present in darkness and identified its mitochondrial sources. By following the fate and components of light-induced extra [Formula: see text] , we estimated the ATP lifetime that lasted up to tens of minutes after long illuminations. Based on the relationship between [Formula: see text] and CF1Fo activity, we conclude that the dithiol configuration in vivo facilitates photosynthesis by driving the same ATP synthesis rate at a significative lower [Formula: see text] than in the γ-disulfide state. The presented in vivo findings are an additional proof of the importance of CF1Fo thiol modulation, reconciling biochemical in vitro studies and structural insights.
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Affiliation(s)
- Felix Buchert
- Laboratory of Chloroplast Biology and Light-Sensing in Microalgae - UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France; Institute of Plant Biology and Biotechnology, University of Münster, Schlossplatz 8, 48143 Münster, Germany.
| | - Benjamin Bailleul
- Laboratory of Chloroplast Biology and Light-Sensing in Microalgae - UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France
| | - Pierre Joliot
- Laboratory of Chloroplast Biology and Light-Sensing in Microalgae - UMR7141, IBPC, CNRS-Sorbonne Université, Paris, France
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8
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Long M, Peltekis A, González-Fernández C, Hégaret H, Bailleul B. Allelochemicals of Alexandrium minutum: Kinetics of membrane disruption and photosynthesis inhibition in a co-occurring diatom. Harmful Algae 2021; 103:101997. [PMID: 33980437 DOI: 10.1016/j.hal.2021.101997] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2020] [Revised: 01/29/2021] [Accepted: 02/01/2021] [Indexed: 06/12/2023]
Abstract
Allelopathy is an efficient strategy by which some microalgae can outcompete other species. Allelochemicals from the toxic dinoflagellate Alexandrium minutum have deleterious effects on diatoms, inhibiting metabolism and photosynthesis and therefore give a competitive advantage to the dinoflagellate. The precise mechanisms of allelochemical interactions and the molecular target of allelochemicals remain however unknown. To understand the mechanisms, the short-term effects of A. minutum allelochemicals on the physiology of the diatom Chaetoceros muelleri were investigated. The effects of a culture filtrate were measured on the diatom cytoplasmic membrane integrity (polarity and permeability) using flow-cytometry and on the photosynthetic performance using fluorescence and absorption spectroscopy. Within 10 min, the unknown allelochemicals induced a depolarization of the cytoplasmic membranes and an impairment of photosynthesis through the inhibition of the plastoquinone-mediated electron transfer between photosystem II and cytochrome b6f. At longer time of exposure, the cytoplasmic membranes were permeable and the integrity of photosystems I, II and cytochrome b6f was compromised. Our demonstration of the essential role of membranes in this allelochemical interaction provides new insights for the elucidation of the nature of the allelochemicals. The relationship between cytoplasmic membranes and the inhibition of the photosynthetic electron transfer remains however unclear and warrants further investigation.
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Affiliation(s)
- Marc Long
- School of Chemistry, University of Wollongong, NSW 2522, Australia; Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS UBO IRD IFREMER -Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, Rue Dumont d'Urville, 29280 Plouzané, France.
| | - Alexandra Peltekis
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR 7141, Centre National de la Recherche Scientifique (CNRS), Sorbonne université, 75005 Paris, France
| | - Carmen González-Fernández
- Immunobiotechnology for Aquaculture Group, Department of Cell Biology and Histology, Faculty of Biology, Regional Campus of International Excellence "Campus Mare Nostrum", University of Murcia, 30100 Murcia, Spain
| | - Hélène Hégaret
- Laboratoire des Sciences de l'Environnement Marin (LEMAR), UMR 6539 CNRS UBO IRD IFREMER -Institut Universitaire Européen de la Mer, Technopôle Brest-Iroise, Rue Dumont d'Urville, 29280 Plouzané, France
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR 7141, Centre National de la Recherche Scientifique (CNRS), Sorbonne université, 75005 Paris, France.
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9
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Beauzamy L, Delacotte J, Bailleul B, Tanaka K, Nakanishi S, Wollman FA, Lemaître F. Mediator-Microorganism Interaction in Microbial Solar Cell: a Fluo-Electrochemical Insight. Anal Chem 2020; 92:7532-7539. [PMID: 32352279 DOI: 10.1021/acs.analchem.9b05808] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Microbial solar cells that mainly rely on the use of photosynthesic organisms are a promising alternative to photovoltaics for solar electricity production. In that way, we propose a new approach involving electrochemistry and fluorescence techniques. The coupled setup Electro-Pulse-Amplitude-Modulation ("e-PAM") enables the simultaneous recording of the produced photocurrent and fluorescence signals from the photosynthetic chain. This methodology was validated with a suspension of green alga Chlamydomonas reinhardtii in interaction with an exogenous redox mediator (2,6-dichlorobenzoquinone; DCBQ). The balance between photosynthetic chain events (PSII photochemical yield, quenching) and the extracted electricity can be monitored overtime. More particularly, the nonphotochemical quenching induced by DCBQ mirrors the photocurrent. This setup thus helps to distinguish the electron harvesting from some side effects due to quinones in real time. It therefore paves the way for future analyses devoted to the choice of the experimental conditions (redox mediator, photosynthetic organisms, and so on) to find the best electron extraction.
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Affiliation(s)
- Léna Beauzamy
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France.,Institut de Biologie Physico-Chimique, UMR7141 Biologie du Chloroplaste et Perception de la Lumière Chez les Micro-Algues, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Jérôme Delacotte
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, UMR7141 Biologie du Chloroplaste et Perception de la Lumière Chez les Micro-Algues, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | | | | | - Francis-André Wollman
- Institut de Biologie Physico-Chimique, UMR7141 Biologie du Chloroplaste et Perception de la Lumière Chez les Micro-Algues, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Frédéric Lemaître
- PASTEUR, Département de Chimie, École Normale Supérieure, PSL University, Sorbonne Université, CNRS, 75005 Paris, France
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10
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Falciatore A, Jaubert M, Bouly JP, Bailleul B, Mock T. Diatom Molecular Research Comes of Age: Model Species for Studying Phytoplankton Biology and Diversity. Plant Cell 2020; 32:547-572. [PMID: 31852772 PMCID: PMC7054031 DOI: 10.1105/tpc.19.00158] [Citation(s) in RCA: 51] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Revised: 10/18/2019] [Accepted: 12/13/2019] [Indexed: 05/08/2023]
Abstract
Diatoms are the world's most diverse group of algae, comprising at least 100,000 species. Contributing ∼20% of annual global carbon fixation, they underpin major aquatic food webs and drive global biogeochemical cycles. Over the past two decades, Thalassiosira pseudonana and Phaeodactylum tricornutum have become the most important model systems for diatom molecular research, ranging from cell biology to ecophysiology, due to their rapid growth rates, small genomes, and the cumulative wealth of associated genetic resources. To explore the evolutionary divergence of diatoms, additional model species are emerging, such as Fragilariopsis cylindrus and Pseudo-nitzschia multistriata Here, we describe how functional genomics and reverse genetics have contributed to our understanding of this important class of microalgae in the context of evolution, cell biology, and metabolic adaptations. Our review will also highlight promising areas of investigation into the diversity of these photosynthetic organisms, including the discovery of new molecular pathways governing the life of secondary plastid-bearing organisms in aquatic environments.
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Affiliation(s)
- Angela Falciatore
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR7141 Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 75005 Paris, France
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR7238 Sorbonne Université, 75005 Paris, France
| | - Marianne Jaubert
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR7141 Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 75005 Paris, France
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR7238 Sorbonne Université, 75005 Paris, France
| | - Jean-Pierre Bouly
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR7141 Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 75005 Paris, France
- Institut de Biologie Paris-Seine, Laboratory of Computational and Quantitative Biology, UMR7238 Sorbonne Université, 75005 Paris, France
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, Laboratory of Chloroplast Biology and Light Sensing in Microalgae, UMR7141 Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 75005 Paris, France
| | - Thomas Mock
- School of Environmental Sciences, University of East Anglia, Norwich Research Park, Norwich NR4 7TJ, United Kingdom
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11
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Dow L, Stock F, Peltekis A, Szamosvári D, Prothiwa M, Lapointe A, Böttcher T, Bailleul B, Vyverman W, Kroth PG, Lepetit B. The Multifaceted Inhibitory Effects of an Alkylquinolone on the Diatom Phaeodactylum tricornutum. Chembiochem 2020; 21:1206-1216. [PMID: 31747114 PMCID: PMC7217009 DOI: 10.1002/cbic.201900612] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Indexed: 01/30/2023]
Abstract
The mechanisms underlying interactions between diatoms and bacteria are crucial to understand diatom behaviour and proliferation, and can result in far‐reaching ecological consequences. Recently, 2‐alkyl‐4‐quinolones have been isolated from marine bacteria, both of which (the bacterium and isolated chemical) inhibited growth of microalgae, suggesting these compounds could mediate diatom–bacteria interactions. The effects of several quinolones on three diatom species have been investigated. The growth of all three was inhibited, with half‐maximal inhibitory concentrations reaching the sub‐micromolar range. By using multiple techniques, dual inhibition mechanisms were uncovered for 2‐heptyl‐4‐quinolone (HHQ) in Phaeodactylum tricornutum. Firstly, photosynthetic electron transport was obstructed, primarily through inhibition of the cytochrome b6f complex. Secondly, respiration was inhibited, leading to repression of ATP supply to plastids from mitochondria through organelle energy coupling. These data clearly show how HHQ could modulate diatom proliferation in marine environments.
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Affiliation(s)
- Lachlan Dow
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
| | - Frederike Stock
- Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium
| | - Alexandra Peltekis
- Institut de Biologie Physico-Chimique, CNRS-Sorbonne Université, 13 rue P. et M. Curie, 75005, Paris, France
| | - Dávid Szamosvári
- Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
| | - Michaela Prothiwa
- Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
| | - Adrien Lapointe
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
| | - Thomas Böttcher
- Department of Chemistry, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, CNRS-Sorbonne Université, 13 rue P. et M. Curie, 75005, Paris, France
| | - Wim Vyverman
- Department of Biology, Ghent University, Krijgslaan 281/S8, 9000, Ghent, Belgium
| | - Peter G Kroth
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
| | - Bernard Lepetit
- Department of Biology, University of Konstanz, Universitätsstrasse 10, 78467, Konstanz, Germany
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12
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Nawrocki W, Bailleul B, Cardol P, Rappaport F, Wollman FA, Joliot P. Maximal cyclic electron flow rate is independent of PGRL1 in Chlamydomonas. Biochimica et Biophysica Acta (BBA) - Bioenergetics 2019; 1860:425-432. [DOI: 10.1016/j.bbabio.2019.01.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 12/08/2018] [Accepted: 01/25/2019] [Indexed: 11/30/2022]
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13
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Nawrocki WJ, Bailleul B, Picot D, Cardol P, Rappaport F, Wollman FA, Joliot P. The mechanism of cyclic electron flow. Biochim Biophys Acta Bioenerg 2019; 1860:433-438. [PMID: 30827891 DOI: 10.1016/j.bbabio.2018.12.005] [Citation(s) in RCA: 56] [Impact Index Per Article: 11.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Revised: 12/08/2018] [Accepted: 12/08/2018] [Indexed: 12/16/2022]
Abstract
Apart from the canonical light-driven linear electron flow (LEF) from water to CO2, numerous regulatory and alternative electron transfer pathways exist in chloroplasts. One of them is the cyclic electron flow around Photosystem I (CEF), contributing to photoprotection of both Photosystem I and II (PSI, PSII) and supplying extra ATP to fix atmospheric carbon. Nonetheless, CEF remains an enigma in the field of functional photosynthesis as we lack understanding of its pathway. Here, we address the discrepancies between functional and genetic/biochemical data in the literature and formulate novel hypotheses about the pathway and regulation of CEF based on recent structural and kinetic information.
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Affiliation(s)
- W J Nawrocki
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie, 75005 Paris, France; Laboratoire de Génétique et Physiologie des Microalgues, Institut de Botanique, Université de Liège, 4, Chemin de la Vallée, B-4000 Liège, Belgium.
| | - B Bailleul
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie, 75005 Paris, France
| | - D Picot
- Institut de Biologie Physico-Chimique, UMR 7099 CNRS-UPMC, 13 rue P. et M. Curie, 75005 Paris, France
| | - P Cardol
- Laboratoire de Génétique et Physiologie des Microalgues, Institut de Botanique, Université de Liège, 4, Chemin de la Vallée, B-4000 Liège, Belgium
| | - F Rappaport
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie, 75005 Paris, France
| | - F-A Wollman
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie, 75005 Paris, France
| | - P Joliot
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue P. et M. Curie, 75005 Paris, France
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14
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Stock F, Syrpas M, Graff van Creveld S, Backx S, Blommaert L, Dow L, Stock W, Ruysbergh E, Lepetit B, Bailleul B, Sabbe K, De Kimpe N, Willems A, Kroth PG, Vardi A, Vyverman W, Mangelinckx S. N-Acyl Homoserine Lactone Derived Tetramic Acids Impair Photosynthesis in Phaeodactylum tricornutum. ACS Chem Biol 2019; 14:198-203. [PMID: 30694649 DOI: 10.1021/acschembio.8b01101] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Marine bacteria contribute substantially to nutrient cycling in the oceans and can engage in close interactions with microalgae. Many microalgae harbor characteristic satellite bacteria, many of which participate in N-acyl homoserine lactone (AHL) mediated quorum sensing. In the diffusion-controlled phycosphere, AHLs can reach high local concentrations, with some of them transforming into tetramic acids, compounds with a broad bioactivity. We tested a representative AHL, N-(3-oxododecanoyl) homoserine lactone, and its tetramic acid rearrangement product on the diatom Phaeodactylum tricornutum. While cell growth and photosynthetic efficiency of photosystem II were barely affected by the AHL, exposure to its tetramic acid rearrangement product had a negative effect on photosynthetic efficiency and led to growth inhibition and cell death in the long term, with a minimum inhibitory concentration between 20 and 50 μΜ. These results strengthen the view that AHLs may play an important role in shaping the outcome of microalgae-bacteria interactions.
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Affiliation(s)
- Frederike Stock
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium
| | - Michail Syrpas
- SynBioC, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Shiri Graff van Creveld
- Department of Plant and Environmental Sciences, Faculty of Biochemistry, Weizmann Institute of Science, Il-76100 Rehovot, Israel
| | - Simon Backx
- SynBioC, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Lander Blommaert
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium
- Institut de Biologie Physico-Chimique (IBPC), UMR 7141, Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
| | - Lachlan Dow
- Plant Ecophysiology, Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
| | - Willem Stock
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium
| | - Ewout Ruysbergh
- SynBioC, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Bernard Lepetit
- Plant Ecophysiology, Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique (IBPC), UMR 7141, Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, 13 Rue Pierre et Marie Curie, F-75005 Paris, France
| | - Koen Sabbe
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium
| | - Norbert De Kimpe
- SynBioC, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
| | - Anne Willems
- Laboratory of Microbiology, Department of Biochemistry and Microbiology, Ghent University, B-9000 Ghent, Belgium
| | - Peter G. Kroth
- Plant Ecophysiology, Department of Biology, University of Konstanz, D-78457 Konstanz, Germany
| | - Assaf Vardi
- Department of Plant and Environmental Sciences, Faculty of Biochemistry, Weizmann Institute of Science, Il-76100 Rehovot, Israel
| | - Wim Vyverman
- Protistology and Aquatic Ecology, Department of Biology, Ghent University, Krijgslaan 281/S8, B-9000 Ghent, Belgium
| | - Sven Mangelinckx
- SynBioC, Department of Green Chemistry and Technology, Ghent University, Coupure Links 653, B-9000 Ghent, Belgium
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15
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Nawrocki WJ, Buchert F, Joliot P, Rappaport F, Bailleul B, Wollman FA. Chlororespiration Controls Growth Under Intermittent Light. Plant Physiol 2019; 179:630-639. [PMID: 30498023 PMCID: PMC6426412 DOI: 10.1104/pp.18.01213] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2018] [Accepted: 11/20/2018] [Indexed: 05/25/2023]
Abstract
Whereas photosynthetic function under steady-state light conditions has been well characterized, little is known about its changes that occur in response to light fluctuations. Chlororespiration, a simplified respiratory chain, is widespread across all photosynthetic lineages, but its role remains elusive. Here, we show that chlororespiration plays a crucial role in intermittent-light conditions in the green alga Chlamydomonas reinhardtii Chlororespiration, which is localized in thylakoid membranes together with the photosynthetic electron transfer chain, involves plastoquinone reduction and plastoquinol oxidation by a Plastid Terminal Oxidase (PTOX). We show that PTOX activity is critical for growth under intermittent light, with severe growth defects being observed in a mutant lacking PTOX2, the major plastoquinol oxidase. We demonstrate that the hampered growth results from a major change in the kinetics of redox relaxation of the photosynthetic electron transfer chain during the dark periods. This change, in turn, has a dramatic effect on the physiology of photosynthesis during the light periods, notably stimulating cyclic electron flow at the expense of the linear electron flow.
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Affiliation(s)
- Wojciech J Nawrocki
- Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
| | - Felix Buchert
- Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
| | - Pierre Joliot
- Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
| | - Fabrice Rappaport
- Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
| | - Francis-André Wollman
- Institut de Biologie Physico-Chimique, Unité Mixte de Recherche 7141, Centre National de la Recherche Scientifique-Sorbonne Université, 75005 Paris, France
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16
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Berne N, Fabryova T, Istaz B, Cardol P, Bailleul B. The peculiar NPQ regulation in the stramenopile Phaeomonas sp. challenges the xanthophyll cycle dogma. Biochim Biophys Acta Bioenerg 2018; 1859:491-500. [PMID: 29625087 DOI: 10.1016/j.bbabio.2018.03.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 10/31/2017] [Revised: 03/15/2018] [Accepted: 03/28/2018] [Indexed: 10/17/2022]
Abstract
In changing light conditions, photosynthetic organisms develop different strategies to maintain a fine balance between light harvesting, photochemistry, and photoprotection. One of the most widespread photoprotective mechanisms consists in the dissipation of excess light energy in the form of heat in the photosystem II antenna, which participates to the Non Photochemical Quenching (NPQ) of chlorophyll fluorescence. It is tightly related to the reversible epoxidation of xanthophyll pigments, catalyzed by the two enzymes, the violaxanthin deepoxidase and the zeaxanthin epoxidase. In Phaeomonas sp. (Pinguiophyte, Stramenopiles), we show that the regulation of the heat dissipation process is different from that of the green lineage: the NPQ is strictly proportional to the amount of the xanthophyll pigment zeaxanthin and the xanthophyll cycle enzymes are differently regulated. The violaxanthin deepoxidase is already active in the dark, because of a low luminal pH, and the zeaxanthin epoxidase shows a maximal activity under moderate light conditions, being almost inactive in the dark and under high light. This light-dependency mirrors the one of NPQ: Phaeomonas sp. displays a large NPQ in the dark as well as under high light, which recovers under moderate light. Our results pinpoint zeaxanthin epoxidase activity as the prime regulator of NPQ in Phaeomonas sp. and therefore challenge the deepoxidase-regulated xanthophyll cycle dogma.
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Affiliation(s)
- N Berne
- Genetics and Physiology of microalgae, PhytoSYSTEMS/InBioS, Université de Liège, B-4000 Liège, Belgium
| | - T Fabryova
- Genetics and Physiology of microalgae, PhytoSYSTEMS/InBioS, Université de Liège, B-4000 Liège, Belgium
| | - B Istaz
- Genetics and Physiology of microalgae, PhytoSYSTEMS/InBioS, Université de Liège, B-4000 Liège, Belgium
| | - P Cardol
- Genetics and Physiology of microalgae, PhytoSYSTEMS/InBioS, Université de Liège, B-4000 Liège, Belgium.
| | - B Bailleul
- Genetics and Physiology of microalgae, PhytoSYSTEMS/InBioS, Université de Liège, B-4000 Liège, Belgium.
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17
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Massoz S, Hanikenne M, Bailleul B, Coosemans N, Radoux M, Miranda-Astudillo H, Cardol P, Larosa V, Remacle C. In vivo chlorophyll fluorescence screening allows the isolation of a Chlamydomonas mutant defective for NDUFAF3, an assembly factor involved in mitochondrial complex I assembly. Plant J 2017; 92:584-595. [PMID: 28857403 DOI: 10.1111/tpj.13677] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2017] [Revised: 08/11/2017] [Accepted: 08/21/2017] [Indexed: 05/16/2023]
Abstract
The qualitative screening method used to select complex I mutants in the microalga Chlamydomonas, based on reduced growth under heterotrophic conditions, is not suitable for high-throughput screening. In order to develop a fast screening method based on measurements of chlorophyll fluorescence, we first demonstrated that complex I mutants displayed decreased photosystem II efficiency in the genetic background of a photosynthetic mutation leading to reduced formation of the electrochemical proton gradient in the chloroplast (pgrl1 mutation). In contrast, single mutants (complex I and pgrl1 mutants) could not be distinguished from the wild type by their photosystem II efficiency under the conditions tested. We next performed insertional mutagenesis on the pgrl1 mutant. Out of about 3000 hygromycin-resistant insertional transformants, 46 had decreased photosystem II efficiency and three were complex I mutants. One of the mutants was tagged and whole genome sequencing identified the resistance cassette in NDUFAF3, a homolog of the human NDUFAF3 gene, encoding for an assembly factor involved in complex I assembly. Complemented strains showed restored complex I activity and assembly. Overall, we describe here a screening method which is fast and particularly suited for the identification of Chlamydomonas complex I mutants.
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Affiliation(s)
- Simon Massoz
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Marc Hanikenne
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- InBioS - Functional Genomics and Plant Molecular Imaging, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Benjamin Bailleul
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Nadine Coosemans
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Michèle Radoux
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Hector Miranda-Astudillo
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Pierre Cardol
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Véronique Larosa
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
| | - Claire Remacle
- InBioS - Genetics and Physiology of Microalgae, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
- PhytoSYSTEMS, Chemin de la vallée, 4, 4000 Liège, University of Liège, Belgium
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18
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Fridman S, Flores-Uribe J, Larom S, Alalouf O, Liran O, Yacoby I, Salama F, Bailleul B, Rappaport F, Ziv T, Sharon I, Cornejo-Castillo FM, Philosof A, Dupont CL, Sánchez P, Acinas SG, Rohwer FL, Lindell D, Béjà O. A myovirus encoding both photosystem I and II proteins enhances cyclic electron flow in infected Prochlorococcus cells. Nat Microbiol 2017; 2:1350-1357. [PMID: 28785078 DOI: 10.1038/s41564-017-0002-9] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Accepted: 06/28/2017] [Indexed: 01/27/2023]
Abstract
Cyanobacteria are important contributors to primary production in the open oceans. Over the past decade, various photosynthesis-related genes have been found in viruses that infect cyanobacteria (cyanophages). Although photosystem II (PSII) genes are common in both cultured cyanophages and environmental samples 1-4 , viral photosystem I (vPSI) genes have so far only been detected in environmental samples 5,6 . Here, we have used a targeted strategy to isolate a cyanophage from the tropical Pacific Ocean that carries a PSI gene cassette with seven distinct PSI genes (psaJF, C, A, B, K, E, D) as well as two PSII genes (psbA, D). This cyanophage, P-TIM68, belongs to the T4-like myoviruses, has a prolate capsid, a long contractile tail and infects Prochlorococcus sp. strain MIT9515. Phage photosynthesis genes from both photosystems are expressed during infection, and the resultant proteins are incorporated into membranes of the infected host. Moreover, photosynthetic capacity in the cell is maintained throughout the infection cycle with enhancement of cyclic electron flow around PSI. Analysis of metagenomic data from the Tara Oceans expedition 7 shows that phages carrying PSI gene cassettes are abundant in the tropical Pacific Ocean, composing up to 28% of T4-like cyanomyophages. They are also present in the tropical Indian and Atlantic Oceans. P-TIM68 populations, specifically, compose on average 22% of the PSI-gene-cassette carrying phages. Our results suggest that cyanophages carrying PSI and PSII genes are likely to maintain and even manipulate photosynthesis during infection of their Prochlorococcus hosts in the tropical oceans.
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Affiliation(s)
- Svetlana Fridman
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - José Flores-Uribe
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Shirley Larom
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Onit Alalouf
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Oded Liran
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Iftach Yacoby
- Department of Molecular Biology and Ecology of Plants, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Faris Salama
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS and Université Pierre et Marie Curie, 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Fabrice Rappaport
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS and Université Pierre et Marie Curie, 13 rue Pierre et Marie Curie, 75005, Paris, France
| | - Tamar Ziv
- Smoler Proteomics Center, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Itai Sharon
- Migal Galilee Research Institute, Kiryat Shmona, 11016, Israel.,Tel Hai College, Upper Galilee, 12210, Israel
| | - Francisco M Cornejo-Castillo
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, 08003, Barcelona, Spain
| | - Alon Philosof
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Christopher L Dupont
- Microbial and Environmental Genomics, J. Craig Venter Institute, La Jolla, CA, 92037, USA
| | - Pablo Sánchez
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, 08003, Barcelona, Spain
| | - Silvia G Acinas
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM), CSIC, 08003, Barcelona, Spain
| | - Forest L Rohwer
- Department of Biology, San Diego State University, San Diego, CA, 92182, USA
| | - Debbie Lindell
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
| | - Oded Béjà
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel.
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Flori S, Jouneau PH, Bailleul B, Gallet B, Estrozi LF, Moriscot C, Bastien O, Eicke S, Schober A, Bártulos CR, Maréchal E, Kroth PG, Petroutsos D, Zeeman S, Breyton C, Schoehn G, Falconet D, Finazzi G. Plastid thylakoid architecture optimizes photosynthesis in diatoms. Nat Commun 2017. [PMID: 28631733 PMCID: PMC5481826 DOI: 10.1038/ncomms15885] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Photosynthesis is a unique process that allows independent colonization of the land by plants and of the oceans by phytoplankton. Although the photosynthesis process is well understood in plants, we are still unlocking the mechanisms evolved by phytoplankton to achieve extremely efficient photosynthesis. Here, we combine biochemical, structural and in vivo physiological studies to unravel the structure of the plastid in diatoms, prominent marine eukaryotes. Biochemical and immunolocalization analyses reveal segregation of photosynthetic complexes in the loosely stacked thylakoid membranes typical of diatoms. Separation of photosystems within subdomains minimizes their physical contacts, as required for improved light utilization. Chloroplast 3D reconstruction and in vivo spectroscopy show that these subdomains are interconnected, ensuring fast equilibration of electron carriers for efficient optimum photosynthesis. Thus, diatoms and plants have converged towards a similar functional distribution of the photosystems although via different thylakoid architectures, which likely evolved independently in the land and the ocean. Phytoplankton and plant plastids have distinct evolutionary origins and membrane organization. Here Flori et al. show that diatom photosynthetic complexes spatially segregate into interconnected subdomains within loose thylakoid stacks enabling fast diffusion of electron carriers and efficient photosynthesis
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Affiliation(s)
- Serena Flori
- Université Grenoble Alpes (UGA), Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), CEA-Grenoble, 38000 Grenoble, France
| | - Pierre-Henri Jouneau
- Laboratoire d'Etudes des Matériaux par Microscopie Avancée, Institut Nanosciences et Cryogénie, Service de Physique des Matériaux et Microstructures, CEA-Grenoble, 38000 Grenoble Cédex 9, France
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique (IBPC), UMR 7141, CNRS and Université Pierre et Marie Curie (UPMC), 75005 Paris, France
| | - Benoit Gallet
- CNRS, UMR 5075 CNRS, CEA, UGA, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Leandro F Estrozi
- CNRS, UMR 5075 CNRS, CEA, UGA, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Christine Moriscot
- CNRS, UMR 5075 CNRS, CEA, UGA, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Olivier Bastien
- Université Grenoble Alpes (UGA), Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), CEA-Grenoble, 38000 Grenoble, France
| | - Simona Eicke
- Plant Biochemistry, Department of Biology, ETH Zurich, CH-8092 Zürich, Switzerland
| | - Alexander Schober
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | | | - Eric Maréchal
- Université Grenoble Alpes (UGA), Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), CEA-Grenoble, 38000 Grenoble, France
| | - Peter G Kroth
- Department of Biology, University of Konstanz, 78457 Konstanz, Germany
| | - Dimitris Petroutsos
- Université Grenoble Alpes (UGA), Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), CEA-Grenoble, 38000 Grenoble, France
| | - Samuel Zeeman
- Plant Biochemistry, Department of Biology, ETH Zurich, CH-8092 Zürich, Switzerland
| | - Cécile Breyton
- CNRS, UMR 5075 CNRS, CEA, UGA, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Guy Schoehn
- CNRS, UMR 5075 CNRS, CEA, UGA, Institut de Biologie Structurale, 38000 Grenoble, France
| | - Denis Falconet
- Université Grenoble Alpes (UGA), Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), CEA-Grenoble, 38000 Grenoble, France
| | - Giovanni Finazzi
- Université Grenoble Alpes (UGA), Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut National de la Recherche Agronomique (INRA), Institut de Biosciences et Biotechnologie de Grenoble (BIG), CEA-Grenoble, 38000 Grenoble, France
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20
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Taddei L, Stella GR, Rogato A, Bailleul B, Fortunato AE, Annunziata R, Sanges R, Thaler M, Lepetit B, Lavaud J, Jaubert M, Finazzi G, Bouly JP, Falciatore A. Multisignal control of expression of the LHCX protein family in the marine diatom Phaeodactylum tricornutum. J Exp Bot 2016; 67:3939-51. [PMID: 27225826 PMCID: PMC4915529 DOI: 10.1093/jxb/erw198] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Diatoms are phytoplanktonic organisms that grow successfully in the ocean where light conditions are highly variable. Studies of the molecular mechanisms of light acclimation in the marine diatom Phaeodactylum tricornutum show that carotenoid de-epoxidation enzymes and LHCX1, a member of the light-harvesting protein family, both contribute to dissipate excess light energy through non-photochemical quenching (NPQ). In this study, we investigate the role of the other members of the LHCX family in diatom stress responses. Our analysis of available genomic data shows that the presence of multiple LHCX genes is a conserved feature of diatom species living in different ecological niches. Moreover, an analysis of the levels of four P. tricornutum LHCX transcripts in relation to protein expression and photosynthetic activity indicates that LHCXs are differentially regulated under different light intensities and nutrient starvation, mostly modulating NPQ capacity. We conclude that multiple abiotic stress signals converge to regulate the LHCX content of cells, providing a way to fine-tune light harvesting and photoprotection. Moreover, our data indicate that the expansion of the LHCX gene family reflects functional diversification of its members which could benefit cells responding to highly variable ocean environments.
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Affiliation(s)
- Lucilla Taddei
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Giulio Rocco Stella
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France Department of Biotechnology, University of Verona, Strada Le Grazie, I-37134 Verona, Italy
| | - Alessandra Rogato
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France Institute of Biosciences and BioResources, CNR, Via P. Castellino 111, 80131 Naples, Italy Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Benjamin Bailleul
- Institut de Biologie Physico-Chimique, UMR 7141 CNRS-UPMC, 13 rue Pierre et Marie Curie, 75005 Paris, France
| | - Antonio Emidio Fortunato
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Rossella Annunziata
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Remo Sanges
- Biology and Evolution of Marine Organisms, Stazione Zoologica Anton Dohrn, Villa Comunale, 80121 Naples, Italy
| | - Michael Thaler
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Bernard Lepetit
- Zukunftskolleg, Department of Plant Ecophysiology, University of Konstanz, D-78457 Konstanz, Germany
| | - Johann Lavaud
- UMI 3376 TAKUVIK, CNRS/Université Laval, Département de Biologie, Pavillon Alexandre-Vachon, 1045 avenue de la Médecine, Québec (Québec) G1V 0A6, Canada
| | - Marianne Jaubert
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Giovanni Finazzi
- Laboratoire de Physiologie Cellulaire et Végétale, UMR 5168, Centre National de la Recherche Scientifique (CNRS), Institut National Recherche Agronomique (INRA), Université Grenoble Alpes, Commissariat à l'Energie Atomique et aux Energies Alternatives (CEA), Institut de Biosciences et Biotechnologies de Grenoble, (BIG), CEA Grenoble, F-38054 Grenoble cedex 9, France
| | - Jean-Pierre Bouly
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
| | - Angela Falciatore
- Sorbonne Universités, UPMC, Institut de Biologie Paris-Seine, CNRS, Laboratoire de Biologie Computationnelle et Quantitative, 15 rue de l'Ecole de Médecine, 75006 Paris, France
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21
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Godaux D, Bailleul B, Berne N, Cardol P. Induction of Photosynthetic Carbon Fixation in Anoxia Relies on Hydrogenase Activity and Proton-Gradient Regulation-Like1-Mediated Cyclic Electron Flow in Chlamydomonas reinhardtii. Plant Physiol 2015; 168:648-58. [PMID: 25931521 PMCID: PMC4453779 DOI: 10.1104/pp.15.00105] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 04/30/2015] [Indexed: 05/19/2023]
Abstract
The model green microalga Chlamydomonas reinhardtii is frequently subject to periods of dark and anoxia in its natural environment. Here, by resorting to mutants defective in the maturation of the chloroplastic oxygen-sensitive hydrogenases or in Proton-Gradient Regulation-Like1 (PGRL1)-dependent cyclic electron flow around photosystem I (PSI-CEF), we demonstrate the sequential contribution of these alternative electron flows (AEFs) in the reactivation of photosynthetic carbon fixation during a shift from dark anoxia to light. At light onset, hydrogenase activity sustains a linear electron flow from photosystem II, which is followed by a transient PSI-CEF in the wild type. By promoting ATP synthesis without net generation of photosynthetic reductants, the two AEF are critical for restoration of the capacity for carbon dioxide fixation in the light. Our data also suggest that the decrease in hydrogen evolution with time of illumination might be due to competition for reduced ferredoxins between ferredoxin-NADP(+) oxidoreductase and hydrogenases, rather than due to the sensitivity of hydrogenase activity to oxygen. Finally, the absence of the two alternative pathways in a double mutant pgrl1 hydrogenase maturation factor G-2 is detrimental for photosynthesis and growth and cannot be compensated by any other AEF or anoxic metabolic responses. This highlights the role of hydrogenase activity and PSI-CEF in the ecological success of microalgae in low-oxygen environments.
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Affiliation(s)
- Damien Godaux
- Department of Life Sciences, Genetics and Physiology of Microalgae, PhytoSYSTEMS, University of Liège, B-4000 Liège, Belgium
| | - Benjamin Bailleul
- Department of Life Sciences, Genetics and Physiology of Microalgae, PhytoSYSTEMS, University of Liège, B-4000 Liège, Belgium
| | - Nicolas Berne
- Department of Life Sciences, Genetics and Physiology of Microalgae, PhytoSYSTEMS, University of Liège, B-4000 Liège, Belgium
| | - Pierre Cardol
- Department of Life Sciences, Genetics and Physiology of Microalgae, PhytoSYSTEMS, University of Liège, B-4000 Liège, Belgium
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22
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Massoz S, Larosa V, Plancke C, Lapaille M, Bailleul B, Pirotte D, Radoux M, Leprince P, Coosemans N, Matagne RF, Remacle C, Cardol P. Inactivation of genes coding for mitochondrial Nd7 and Nd9 complex I subunits in Chlamydomonas reinhardtii. Impact of complex I loss on respiration and energetic metabolism. Mitochondrion 2014; 19 Pt B:365-74. [DOI: 10.1016/j.mito.2013.11.004] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2013] [Revised: 11/22/2013] [Accepted: 11/26/2013] [Indexed: 02/04/2023]
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23
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Roberty S, Bailleul B, Berne N, Franck F, Cardol P. PSI Mehler reaction is the main alternative photosynthetic electron pathway in Symbiodinium sp., symbiotic dinoflagellates of cnidarians. New Phytol 2014; 204:81-91. [PMID: 24975027 DOI: 10.1111/nph.12903] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2014] [Accepted: 05/17/2014] [Indexed: 05/04/2023]
Abstract
Photosynthetic organisms have developed various photoprotective mechanisms to cope with exposure to high light intensities. In photosynthetic dinoflagellates that live in symbiosis with cnidarians, the nature and relative amplitude of these regulatory mechanisms are a matter of debate. In our study, the amplitude of photosynthetic alternative electron flows (AEF) to oxygen (chlororespiration, Mehler reaction), the mitochondrial respiration and the Photosystem I (PSI) cyclic electron flow were investigated in strains belonging to three clades (A1, B1 and F1) of Symbiodinium. Cultured Symbiodinium strains were maintained under identical environmental conditions, and measurements of oxygen evolution, fluorescence emission and absorption changes at specific wavelengths were used to evaluate PSI and PSII electron transfer rates (ETR). A light- and O2 -dependent ETR was observed in all strains. This electron transfer chain involves PSII and PSI and is insensitive to inhibitors of mitochondrial activity and carbon fixation. We demonstrate that in all strains, the Mehler reaction responsible for photoreduction of oxygen by the PSI under high light, is the main AEF at the onset and at the steady state of photosynthesis. This sustained photosynthetic AEF under high light intensities acts as a photoprotective mechanism and leads to an increase of the ATP/NADPH ratio.
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Affiliation(s)
- Stéphane Roberty
- Laboratoire d'Ecologie Animale et d'Ecotoxicologie, Département de Biologie, Ecologie et Evolution, Université de Liège, 11 Allée du 6 Août, B-4000, Liège, Belgium
- Laboratoire de Bioénergétique, Institut de Botanique, Université de Liège, 27 Bld du Rectorat, B-4000, Liège, Belgium
| | - Benjamin Bailleul
- Laboratoire de Génétique et Physiologie des Microalgues, Institut de Botanique, Université de Liège, 27 Bld du Rectorat, B-4000, Liège, Belgium
| | - Nicolas Berne
- Laboratoire de Génétique et Physiologie des Microalgues, Institut de Botanique, Université de Liège, 27 Bld du Rectorat, B-4000, Liège, Belgium
| | - Fabrice Franck
- Laboratoire de Bioénergétique, Institut de Botanique, Université de Liège, 27 Bld du Rectorat, B-4000, Liège, Belgium
- PhytoSYSTEMS, Université de Liège, B-4000, Liège, Belgium
| | - Pierre Cardol
- Laboratoire de Génétique et Physiologie des Microalgues, Institut de Botanique, Université de Liège, 27 Bld du Rectorat, B-4000, Liège, Belgium
- PhytoSYSTEMS, Université de Liège, B-4000, Liège, Belgium
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24
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Santabarbara S, Bailleul B, Redding K, Barber J, Rappaport F, Telfer A. Kinetics of phyllosemiquinone oxidation in the Photosystem I reaction centre of Acaryochloris marina. Biochimica et Biophysica Acta (BBA) - Bioenergetics 2012; 1817:328-35. [DOI: 10.1016/j.bbabio.2011.10.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 10/10/2011] [Accepted: 10/11/2011] [Indexed: 11/28/2022]
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25
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Bailleul B, Cardol P, Breyton C, Finazzi G. Electrochromism: a useful probe to study algal photosynthesis. Photosynth Res 2010; 106:179-89. [PMID: 20632109 DOI: 10.1007/s11120-010-9579-z] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2010] [Accepted: 06/23/2010] [Indexed: 05/07/2023]
Abstract
In photosynthesis, electron transfer along the photosynthetic chain results in a vectorial transfer of protons from the stroma to the lumenal space of the thylakoids. This promotes the generation of an electrochemical proton gradient (Δμ(H)(+)), which comprises a gradient of electric potential (ΔΨ) and of proton concentration (ΔpH). The Δμ(H)(+) has a central role in the photosynthetic process, providing the energy source for ATP synthesis. It is also involved in many regulatory mechanisms. The ΔpH modulates the rate of electron transfer and triggers deexcitation of excess energy within the light harvesting complexes. The ΔΨ is required for metabolite and protein transport across the membranes. Its presence also induces a shift in the absorption spectra of some photosynthetic pigments, resulting in the so-called ElectroChromic Shift (ECS). In this review, we discuss the characteristic features of the ECS, and illustrate possible applications for the study of photosynthetic processes in vivo.
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Affiliation(s)
- Benjamin Bailleul
- UMR 7141, Centre National de la Recherche Scientifique, Institut de Biologie Physico-Chimique, Université Pierre et Marie Curie, 75005 Paris, France.
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26
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Bailleul B, Johnson X, Finazzi G, Barber J, Rappaport F, Telfer A. The Thermodynamics and Kinetics of Electron Transfer between Cytochrome b6f and Photosystem I in the Chlorophyll d-dominated Cyanobacterium, Acaryochloris marina. J Biol Chem 2008; 283:25218-25226. [DOI: 10.1074/jbc.m803047200] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
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27
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Moore T, Hecquet S, McLellann A, Ville D, Grid D, Picard F, Moulard B, Asherson P, Makoff AJ, McCormick D, Nashef L, Froguel P, Arzimanoglou A, LeGuern E, Bailleul B. Polymorphism analysis of JRK/JH8, the human homologue of mouse jerky, and description of a rare mutation in a case of CAE evolving to JME. Epilepsy Res 2001; 46:157-67. [PMID: 11463517 DOI: 10.1016/s0920-1211(01)00275-3] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Disruption of the function of the mouse jerky gene by transgene insertion causes generalized recurrent seizures reminiscent of human idiopathic generalized epilepsy (IGE). A human homologue, JRK/JH8, has been cloned, which maps to 8q24, a chromosomal region associated with several forms of IGE. JRK/JH8 is, therefore, a candidate locus for at least some forms of IGE. We report corrected cDNA sequences and extended open reading frames for the mouse jerky and human JRK/JH8 genes, which add 48 amino acids to the N-terminus of the Jerky protein and which extends the region of homology with the N-terminal DNA-binding domain of the centromere-binding protein, CENP-B. Systematic sequencing of the coding region of the extended JRK/JH8 gene identified single nucleotide polymorphisms that define three haplotypes, which were used for association studies in patients with idiopathic generalized epilepsy. We report one subject with childhood absence epilepsy (CAE) that evolved to juvenile myoclonic epilepsy (JME) that has a unique de novo mutation that results in a non-conservative amino acid change at a potential protein glycosylation site. Familial analysis supports a causal role for this mutation in the disease.
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Affiliation(s)
- T Moore
- Department of Biochemistry, University College Cork, Lee Maltings, Prospect Row, Cork, Ireland.
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28
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Mercer JG, Moar KM, Hoggard N, Strosberg AD, Froguel P, Bailleul B. B219/OB-R 5'-UTR and leptin receptor gene-related protein gene expression in mouse brain and placenta: tissue-specific leptin receptor promoter activity. J Neuroendocrinol 2000; 12:649-55. [PMID: 10849209 DOI: 10.1046/j.1365-2826.2000.00501.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Leptin receptor (OB-R) splice variants either encode proteins with different 3' cytoplasmic domains or have different 5' untranslated regions (UTR), indicative of dual promoters. The B219/OB-R promoter transcribes only OB-R transcripts, whereas the OB-R/GRP promoter initiates transcription of both OB-R and another protein of unknown function, called the leptin receptor gene-related protein (OB-RGRP). We compared expression of B219/OB-R 5'-UTR and OB-RGRP mRNAs by in situ hybridization. We thus assessed, by inference, the contributions of the two promoters to the leptin receptor transcript pool, in murine brain or in placenta, a tissue with abundant leptin receptor mRNA. Expression of B219/OB-R 5'-UTR mRNA (and thus by inference B219/OB-R promoter activity) in brain was similar in both distribution and relative intensity to OB-R mRNA. OB-RGRP mRNA (and thus by inference OB-R/GRP promoter activity) was widely distributed in murine brain, with elevated expression in the hypothalamic regions that express the leptin receptor mRNA, including the paraventricular nucleus. B219/OB-R 5'-UTR mRNA, but not OB-RGRP mRNA, was upregulated in hypothalamus of obese ob/ob mice. In placenta, B219/OB-R 5'-UTR mRNA was restricted to the maternal interface, and transcription of both long and short leptin receptor splice variants in the main body of the tissue thus proceeds via the OB-R/GRP promoter, strongly indicative of tissue-specific promoter usage.
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Affiliation(s)
- J G Mercer
- Molecular Neuroendocrinology Group, Rowett Research Institute, Aberdeen, Scotland.
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29
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Godart F, Bellanné-Chantelot C, Clauin S, Gragnoli C, Abderrahmani A, Blanché H, Boutin P, Chèvre JC, Froguel P, Bailleul B. Identification of seven novel nucleotide variants in the hepatocyte nuclear factor-1alpha (TCF1) promoter region in MODY patients. Hum Mutat 2000; 15:173-80. [PMID: 10649494 DOI: 10.1002/(sici)1098-1004(200002)15:2<173::aid-humu6>3.0.co;2-w] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Maturity onset diabetes of the young (MODY) is a heterogeneous subtype of type II diabetes mellitus. To date, five MODY genes have been identified. Mutations in the hepatocyte nuclear factor-1alpha (HNF-1alpha) gene are associated with MODY3. In the present work, we implemented the HNF-1alpha promoter region in the screening of MODY-suspect patients and identified seven variants not detected in control subjects. The family was available for the -119delG variant, and segregration between MODY and the variant is observed. Most of these variants are located in highly conserved regions and may alter HNF-1alpha expression through binding alteration of nuclear factors or other mechanisms. We demonstrate by functional studies that the transcriptional activity of the -283A>C and -218T>C variant promoters were 30% and 70% of the wild type activity, respectively. These data suggest that HNF-1alpha promoter variants could be diabetogenic mutations, and emphasize that the accurate HNF-1alpha expression is important for the maintenance of normal pancreatic beta cell function.
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Affiliation(s)
- F Godart
- Institut de Biologie de Lille, Lille, France
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30
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Vaxillaire M, Abderrahmani A, Boutin P, Bailleul B, Froguel P, Yaniv M, Pontoglio M. Anatomy of a homeoprotein revealed by the analysis of human MODY3 mutations. J Biol Chem 1999; 274:35639-46. [PMID: 10585442 DOI: 10.1074/jbc.274.50.35639] [Citation(s) in RCA: 79] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Hepatocyte nuclear factor 1alpha (HNF1alpha) is an atypical dimeric homeodomain-containing protein that is expressed in liver, intestine, stomach, kidney, and pancreas. Mutations in the HNF1alpha gene are associated with an autosomal dominant form of non-insulin-dependent diabetes mellitus called maturity-onset diabetes of the young (MODY3). More than 80 different mutations have been identified so far, many of which involve highly conserved amino acid residues among vertebrate HNF1alpha. In the present work, we investigated the molecular mechanisms by which MODY3 mutations could affect HNF1alpha function. For this purpose, we analyzed the properties of 10 mutants resulting in amino acid substitutions or protein truncation. Some mutants have a reduced protein stability, whereas others are either defective in the DNA binding or impaired in their intrinsic trans-activation potential. Three mutants, characterized by a complete loss of trans-activation, behave as dominant negatives when transfected with the wild-type protein. These data define a clear causative relationship between MODY3 mutations and functional defects in HNF1alpha trans-activation. In addition, our analysis sheds new light on the structure of a homeoprotein playing a key role in pancreatic beta cell function.
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Affiliation(s)
- M Vaxillaire
- Unité des Virus Oncogènes, Unité de Recherche Associée 1644, Centre National de la Recherche Scientifique, Département des Biotechnologies, Institut Pasteur, 25 rue du Dr Roux, 75724 Paris Cedex 15, France
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31
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Moore T, Constancia M, Zubair M, Bailleul B, Feil R, Sasaki H, Reik W. Multiple imprinted sense and antisense transcripts, differential methylation and tandem repeats in a putative imprinting control region upstream of mouse Igf2. Proc Natl Acad Sci U S A 1997; 94:12509-14. [PMID: 9356480 PMCID: PMC25020 DOI: 10.1073/pnas.94.23.12509] [Citation(s) in RCA: 204] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The mouse insulin-like growth factor 2 (Igf2) locus is a complex genomic region that produces multiple transcripts from alternative promoters. Expression at this locus is regulated by parental imprinting. However, despite the existence of putative imprinting control elements in the Igf2 upstream region, imprinted transcriptional repression is abolished by null mutations at the linked H19 locus. To clarify the extent to which the Igf2 upstream region contains autonomous imprinting control elements we have performed functional and comparative analyses of the region in the mouse and human. Here we report the existence of multiple, overlapping imprinted (maternally repressed) sense and antisense transcripts that are associated with a tandem repeat in the mouse Igf2 upstream region. Regions flanking the repeat exhibit tissue-specific parental allelic methylation patterns, suggesting the existence of tissue-specific control elements in the upstream region. Studies in H19 null mice indicate that both parental allelic methylation and monoallelic expression of the upstream transcripts depends on an intact H19 gene acting in cis. The homologous region in human IGF2 is structurally conserved, with the significant exception that it does not contain a tandem repeat. Our results support the proposal that tandem repeats act to target methylation to imprinted genetic loci.
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Affiliation(s)
- T Moore
- Department of Development and Genetics, The Babraham Institute, Cambridge CB2 4AT, United Kingdom.
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Forné T, Oswald J, Dean W, Saam JR, Bailleul B, Dandolo L, Tilghman SM, Walter J, Reik W. Loss of the maternal H19 gene induces changes in Igf2 methylation in both cis and trans. Proc Natl Acad Sci U S A 1997; 94:10243-8. [PMID: 9294195 PMCID: PMC23347 DOI: 10.1073/pnas.94.19.10243] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Recent investigations have shown that the maintenance of genomic imprinting of the murine insulin-like growth factor 2 (Igf2) gene involves at least two factors: the DNA (cytosine-5-)-methyltransferase activity, which is required to preserve the paternal specific expression of Igf2, and the H19 gene (lying 90 kb downstream of Igf2 gene), which upon inactivation leads to relaxation of the Igf2 imprint. It is not yet clear how these two factors are related to each other in the process of maintenance of Igf2 imprinting and, in particular, whether the latter is acting through cis elements or whether the H19 RNA itself is involved. By using Southern blots and the bisulfite genomic-sequencing technique, we have investigated the allelic methylation patterns (epigenotypes) of the Igf2 gene in two strains of mouse with distinct deletions of the H19 gene. The results show that maternal transmission of H19 gene deletions leads the maternal allele of Igf2 to adopt the epigenotype of the paternal allele and indicate that this phenomenon is influenced directly or indirectly by the H19 gene expression. More importantly, the bisulfite genomic-sequencing allowed us to show that the methylation pattern of the paternal allele of the Igf2 gene is affected in trans by deletions of the active maternal allele of the H19 gene. Selection during development for the appropriate expression of Igf2, dosage-dependent factors that bind to the Igf2 gene, or methylation transfer between the parental alleles could be involved in this trans effect.
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Affiliation(s)
- T Forné
- Laboratory of Developmental Genetics and Imprinting, Department of Development and Genetics, The Babraham Institute, Cambridge CB2 4AT, United Kingdom
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Boutin P, Hani EH, Vasseur F, Roche C, Bailleul B, Hager J, Froguel P. Automated fluorescence-based screening for mutation by SSCP: use of universal M13 dye primers for labeling and detection. Biotechniques 1997; 23:358-62. [PMID: 9298196 DOI: 10.2144/97233bm01] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Affiliation(s)
- P Boutin
- Institut Pasteur de Lille, France
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Abstract
The leptin receptor (OB-R) is a single membrane- spanning protein that mediates the weight-regulatory effects of leptin (OB protein). Several mRNA splice variants have been described which either encode OB-R proteins with cytoplasmic domains of different length or the OB-R and B219/OBR variants, which have different 5'-untranslated regions. Here we report evidence for the synthesis of a human mRNA splice variant of the OB-R gene that potentially encodes a novel protein, leptin receptor gene-related protein (OB-RGRP), which displays no sequence similarity to the leptin receptor itself. This OB-RGRP transcript contains the first two OB-R gene 5'-untranslated exons, but then is alternatively spliced to two novel exons which were mapped to a yeast artificial chromosome containing the leptin receptor gene. First identified by analysis of a large human expressed sequence tag database, the OB-RGRP transcript has now also been found in human and mouse tissues by the use of PCR. Preliminary experiments suggest that OB-RGRP and the OB-R variants share similar patterns of expression that are distinct from that of the B219/OBR variant. OB-RGRP is highly homologous to putative open reading frames in both yeast and Caenorhabditis elegans , suggesting a phylogenetically conserved role for this novel protein.
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Affiliation(s)
- B Bailleul
- Institut Cochin de Génétique Moléculaire, Laboratoire d'ImmunoPharmacologie Moléculaire, CNRS UPR 0415, 22 rue Méchain, 75014 Paris, France.
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Abstract
Circular splicing has already been described on nuclear pre-mRNA for certain splice sites far apart in the multi exonic ETS-1 gene and in the single 1.2 kb exon of the Sry locus. To date, it is unclear how splice site juxtaposition occurs in normal and circular splicing. The splice site selection of an internal exon is likely to involve pairing between splice sites across that exon. Based on this, we predict that, albeit at low frequency, internal exons yield circular RNA by splicing as an error-prone mechanism of exon juxtaposition or, perhaps more interestingly, as a regulated mechanism on alternative exons. To address this question, the circular exon formation was analyzed at three ETS-1 internal exons (one alternative spliced exon and two constitutive), in human cell line and blood cell samples. Here, we show by RT-PCR and sequencing that exon circular splicing occurs at the three individual exons that we examined. RNase protection experiments suggest that there is no correlation between exon circle expression and exon skipping.
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Affiliation(s)
- B Bailleul
- Unite 124 INSERM, Institut de Recherches sur le Cancer de Lille, France
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Abstract
The Ha-ras gene is one of the three oncogenes (Ha-ras, Ki-ras, and N-ras) of the ras superfamily of small G proteins. The p21ras proteins encoded by the ras genes are key proteins involved in the transduction of signals from membrane receptor-tyrosine kinases to downstream targets. The ras genes seem to play a ubiquitous role in the control of cell proliferation and cell differentiation. At the same time, ras genes may perform specific differentiated functions in certain cell types. Little is known about the regulation of expression of the Ha-ras gene. The first intron of the Ha-ras gene has been reported to be highly conserved between human and rodent. We investigated the role that this intron may play in the regulation of expression of Ha-ras. The promoter region of the Ha-ras gene exhibits characteristics of a housekeeping gene. Deletion analysis shows the existence of an enhancer-type element in the 5' region of the first intron (intron 0). DNase 1 footprinting experiments reveal five sites that interact with nuclear proteins from fibroblast and epithelial cell lines. Deletion and site-directed mutagenesis of three of these sites show that two are involved in a positive effect and one in a negative effect on the regulation of expression of the mouse Ha-ras gene.
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Affiliation(s)
- J B Telliez
- INSERM Unite 124, Institut de Recherches sur le Cancer de Lille, France
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Proffitt J, Crabtree G, Grove M, Daubersies P, Bailleul B, Wright E, Plumb M. An ATF/CREB-binding site is essential for cell-specific and inducible transcription of the murine MIP-1 beta cytokine gene. Gene X 1995; 152:173-9. [PMID: 7835696 DOI: 10.1016/0378-1119(94)00701-s] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The murine macrophage inflammatory protein 1 beta mRNA (MIP-1 beta) is rapidly and transiently induced in macrophages by lipopolysaccharide (LPS), serum or cycloheximide. Functional studies of the MIP-1 beta proximal promoter indicate that it is cell-specific, and serum- and LPS-responsive in macrophages. A 76-bp proximal promoter sequence (-51 to -127 bp) confers cell-specific and LPS-inducible activity when placed upstream from a heterologous promoter in both orientations. One essential cis-regulatory element within the enhancer-like sequence is an activating transcription factor/cAMP response element (CRE)-binding protein (ATF/CREB)-binding site, although the promoter is not cAMP responsive. Electrophoretic mobility shift assays and mutational analyses suggest that the promoter site is bound by nuclear protein complexes containing cAMP-independent members of the ATF/CREB family of proteins and c-Jun, and are functionally distinct from the AP1-related TPA-response element (TRE) binding activity.
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Affiliation(s)
- J Proffitt
- ICRF Cancer Medicine Research Unit, St. James's University Hospital, Leeds, UK
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38
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Dupont-Wallois L, Sautière PE, Cocquerelle C, Bailleul B, Delacourte A, Caillet-Boudin ML. Shift from fetal-type to Alzheimer-type phosphorylated Tau proteins in SKNSH-SY 5Y cells treated with okadaic acid. FEBS Lett 1995; 357:197-201. [PMID: 7805890 DOI: 10.1016/0014-5793(94)01361-4] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Tau proteins are abnormally phosphorylated in Alzheimer's disease. Pathological Tau proteins named PHF-Tau 55, PHF-Tau 64, and PHF-Tau 69, are the main constituents of the paired helical filaments (PHF). When treating SKNSH-SY 5Y cells with okadaic acid (OA), Tau 55 protein was clearly induced whereas Tau 64 protein was only faintly induced. Here, we show that the absence of Tau 69 could be explained by the fact that adult isoforms containing N-terminal inserts are not detected. Phosphorylation is similar for untreated cellular Tau proteins and fetal Tau proteins, while OA cell treatment transformed fetal-type into Alzheimer-type phosphorylated proteins.
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Abstract
We previously identified novel human ets-1 transcripts in which the normal order of exons is inverted, and demonstrated that although the order of exons is different than in the genomic DNA, splicing of these exons out of order occurs in pairs using genuine splice sites (1). Here we determine the structure of these novel transcripts, showing that they correspond to circular RNA molecules containing only exons in genomic order. These transcripts are stable molecules, localized in the cytoplasmic component of the cells. To our knowledge, this is the first case of circular transcripts being processed from nuclear pre-mRNA in eukaryotes. This new type of transcript might represent a novel aspect of gene expression and hold some interesting clues about the splicing mechanism.
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Affiliation(s)
- C Cocquerelle
- Unité 124 INSERM, Institut de Recherches sur le Cancer, Lille, France
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40
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Abstract
The ets-1 proto-oncogene codes for a transcription factor. In order to understand how ets-1 is regulated, we have cloned its promoter. We show that the promoter is inducible by serum and expression of c-Fos and c-Jun, and it is positively auto-regulated by its gene product. A 50 base-pair sequence is sufficient to confer c-Fos + c-Jun and c-Ets-1 responsiveness to a heterologous promoter. This element contains two AP1 and one Ets-1 like motifs. Striking, AP-1 and Ets-1 motifs are found in oncogene responsive units (ORU's) of other promoters, suggesting that combining these motifs is a common mechanism for generating mitogen responsive transcription elements.
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Affiliation(s)
- M A Majérus
- Unité 124 INSERM, Institut de Recherches sur le Cancer de Lille, France
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41
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Abstract
Following our studies which showed that the alpha and beta exons of the chicken c-ets-1 gene are not conserved in the human homologue, we succeeded in identifying a novel human c-ets-1 transcript in which the normal order of exons is scrambled. By PCR and RNase protection assays, we demonstrated that while the order of exons is different from that in genomic DNA, splicing of these exons in aberrant order occurs in pairs and at the same conserved consensus splice sites used in the normally spliced transcript. The scrambled transcript is non-polyadenylated and is expressed at much lower levels than the normal transcript. It is not the consequence of genomic rearrangement at the ets-1 locus nor is it due to the transcription of any ets-1 pseudogene. These results confirm previous observations of scrambled splicing.
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Affiliation(s)
- C Cocquerelle
- Unité 124 INSERM, Institut de Recherches sur le Cancer, Lille, France
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42
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Daubersies P, Galiègue-Zouitina S, Koffel-Schwartz N, Fuchs RP, Loucheux-Lefebvre MH, Bailleul B. Mutation spectra of the two guanine adducts of the carcinogen 4-nitroquinoline 1-oxide in Escherichia coli. Influence of neighbouring base sequence on mutagenesis. Carcinogenesis 1992; 13:349-54. [PMID: 1547523 DOI: 10.1093/carcin/13.3.349] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
When the chemical carcinogen 4-nitroquinoline 1-oxide binds to DNA in vitro, two major adducts are formed, both at guanine residues, but at different positions, i.e. the C8 or the N2 position. Well-defined adducts (either C8 or N2 guanine adducts) can be formed in vitro by reacting DNA with 4-actoxyaminoquinoline 1-oxide (Ac-4HAQO) under different reaction conditions. Forward mutations induced by each of both main 4NQO adducts in the tetracycline resistance gene of pBR322 were determined. In total, 30 independent 4NQO-induced mutations were characterized, showing mainly base-pair substitution mutations and some frameshift mutations. We have observed that the 5' neighbouring base influences the specificity of dGuo-N2-AQO induced base-pair substitutions mutagenesis; a similar effect does not occur with dGuo-C8-AQO. This study reveals the importance of the N2 guanine adduct in the mutagenesis induced by 4NQO in vivo.
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Affiliation(s)
- P Daubersies
- Unité 124 INSERM, Institut de Recherches sur le Cancer de Lille, France
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43
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Abstract
Previous studies have demonstrated that the mouse c-Harvey ras proto-oncogene (c-Ha-ras) promoter sequences are GC rich and contain several potential transcription factor SP1 binding sites. We investigated the endonuclease hypersensitivity of this region in nuclei in vitro and whole mouse tissues in vivo and identified a very strong, ubiquitous hypersensitive site covering the proximal promoter sequences. Footprint protection studies using nuclear extracts from various cell types including fibroblasts, erythroid cells, and both normal and transformed epithelial cells revealed a consistent protein-binding pattern. Five protein binding sites were observed, four of which correlated with potential SP1 binding sites. Competition experiments using an oligonucleotide corresponding to a consensus SP1 binding site confirmed that these sequences were indeed bound by the SP1 (or SP1-like) trans-acting factor. In addition, no differences were observed between the footprint patterns obtained using extracts from cells of different lineages or between normal and transformed epithelial cells carrying activated ras genes. The controlling elements responsible for differential c-Ha-ras transcription between cell types or at different stages of carcinogenesis therefore probably lie in other regions of the gene.
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Affiliation(s)
- M Plumb
- Beatson Institute for Cancer Research, Glasgow, Scotland
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Fronza G, Tornaletti S, Menichini P, Galiègue-Zouitina S, Bailleul B, Loucheux-Lefebvre MH, Abbondandolo A, Pedrini AM. Extent of helix perturbation associated with DNA modification by the o-acetyl derivative of the carcinogen 4-hydroxyaminoquinoline-1-oxide. Biochim Biophys Acta 1990; 1087:330-5. [PMID: 2248980 DOI: 10.1016/0167-4781(90)90007-o] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Duplex unwinding associated with DNA modification by 4-acetoxyaminoquinoline-1-oxide, a model ultimate carcinogen of 4-nitroquinoline-1-oxide, has been determined by the agarose gel electrophoresis band-shift method. An average unwinding angle per stable adduct of -15.1 degrees +/- 1.5 degrees for negatively supercoiled topoisomers and -6.5 degrees +/- 1.4 degrees for positively supercoiled topoisomers was obtained. Because of the different proportion of stable adducts (dGuo-N2-AQO, dGuo-C8-AQO, dAdo-N6-AQO) between negatively (8:1.5:0.5) and positively (5:2.5:1) supercoiled topoisomers, the difference in unwinding angles is suggestive of a diverse contribution of the various adducts to the overall conformational change. Since the largest unwinding angle was coupled with the highest proportion of dGuo-N2-AQO adduct, it is likely that this adduct is the most distortive lesion. A contribution of sites of base loss to DNA unwinding was also observed.
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Affiliation(s)
- G Fronza
- Instituto Nazionale per la Ricerca sul Cancro, Genova, Italy
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45
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Bailleul B, Surani MA, White S, Barton SC, Brown K, Blessing M, Jorcano J, Balmain A. Skin hyperkeratosis and papilloma formation in transgenic mice expressing a ras oncogene from a suprabasal keratin promoter. Cell 1990; 62:697-708. [PMID: 1696852 DOI: 10.1016/0092-8674(90)90115-u] [Citation(s) in RCA: 207] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The promoter region of the suprabasal keratin 10 gene has been used to direct expression of a mutant human Harvey-ras oncogene to the differentiating cells of the mouse epidermis. Transgenic animals develop hyperkeratosis of the skin and forestomach--the two sites known to express high levels of the keratin 10 polypeptide in vivo. Papillomas subsequently develop on the skin surface, initially at sites subject to biting or scratching such as the base of the tail or behind the ears. The results suggest that the "second event" involved in tumor development in these transgenic animals is the local induction of a mild wounding stimulus. Furthermore, because the H-ras transgene is expressed in suprabasal cells, it appears that cells which have left the stem cell compartment can be induced to form at least benign tumors in vivo.
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Affiliation(s)
- B Bailleul
- Beatson Institute for Cancer Research, Garscube Estate, Bearsden, Glasgow, Scotland
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Galiègue-Zouitina S, Daubersies P, Loucheux-Lefebvre MH, Bailleul B. Mutagenicity of N2 guanylarylation is SOS functions dependent and reminiscent of the high mutagenic property of 4NQO. Carcinogenesis 1989; 10:1961-6. [PMID: 2507192 DOI: 10.1093/carcin/10.10.1961] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
A comparison of the mutagenic potency of the N2 and the C8 guanylarylation of DNA by 4-nitroquinoline 1-oxide (4NQO) was established. The induced mutagenicity by the N2 guanine adduct is dependent on the SOS functions in the host and requires the umuC gene product. This lesion is repaired by the excision repair system and efficiently blocks the replication machinery. The data obtained with the C8 adduct show that this lesion is weakly toxic in the wild-type strain Escherichia coli probably because the efficiency of the replication is affected. This adduct is three times less mutagenic than the N2 adduct. These results suggest that in vivo the high mutagenicity of 4NQO can mainly be ascribed to the N2 guanine adduct.
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47
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Menichini P, Fronza G, Tornaletti S, Galiègue-Zouitina S, Bailleul B, Loucheux-Lefebvre MH, Abbondandolo A, Pedrini AM. In vitro DNA modification by the ultimate carcinogen of 4-nitroquinoline-1-oxide: influence of superhelicity. Carcinogenesis 1989; 10:1589-93. [PMID: 2548748 DOI: 10.1093/carcin/10.9.1589] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
The effect of DNA tertiary structure on in vitro modification by 4-acetoxy-aminoquinoline-1-oxide (Ac-4-HAQO) was investigated. The reactivity of pAT153 plasmid DNA depended on the conformational state of the molecule: it progressively decreased according to the decrease of the superhelical tension, being negatively supercoiled DNA about two times more susceptible than singly-nicked relaxed DNA. HPLC of the three main Ac-4-HAQO adducts showed that 3-(deoxyguanosin-N2-yl)-4-aminoquinoline-1-oxide, N-(deoxyguanosin-C8-yl)-4-aminoquinoline-1-oxide and 3-(deoxyadenosin-N6-yl)-4-aminoquinoline-1-oxide accounted for 50, 25 and 10% of total quinoline DNA base adducts in all DNA conformations tested, except in the negatively supercoiled topoisomers where they accounted for 80, 15 and 5% respectively. DNA modification by Ac-4-HAQO resulted also in the formation of apurinic/apyrimidinic sites and in strand scissions. The quantification of these damages revealed that they represent an important fraction of all damaging events and that their yield is also influenced by DNA superstructure. Thus, these lesions must be considered as important DNA damage induced by Ac-4-HAQO.
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Affiliation(s)
- P Menichini
- Istituto Nazionale per la Ricerca sul Cancro, Genova, Italy
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48
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Affiliation(s)
- B Bailleul
- Unité INSERM n 124, Institut de Recherches sur le Cancer de Lille, France
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49
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Bailleul B, Brown K, Ramsden M, Akhurst RJ, Fee F, Balmain A. Chemical induction of oncogene mutations and growth factor activity in mouse skin carcinogenesis. Environ Health Perspect 1989; 81:23-7. [PMID: 2667981 PMCID: PMC1567527 DOI: 10.1289/ehp.898123] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/02/2023]
Abstract
The goal of understanding the molecular basis of human tumor development has been greatly facilitated by the use of animal model systems in which the etiology of tumor development can be carefully controlled. Environmental chemicals, either naturally occurring or artificially produced, are thought to make a major contribution to the human tumor burden. Many of the concepts of multistage carcinogenesis have been developed and refined using the mouse skin model system and the work described in this article has been carried out in an attempt to analyze the molecular changes that are associated with the initiation of tumor development, the selection of initiated cells to form papillomas, or the progression of premalignant tumors to carcinoma. We have analyzed a number of skin tumors induced in mice by a two-stage initiation and promotion protocol and have detected a high frequency of c-ras oncogene mutations in this system. The mutation found in each case correlates well with the known reactivity of the carcinogens used. It has also been shown that where ras activation occurs this represents an early event in the tumor model system. Transforming growth factor beta is induced in mouse skin by tumor promoter treatment and may therefore play a role in the selection of initiated cells to form papillomas. Additional events, some of which involve the loss of normal ras alleles and possibly tumor suppressor genes, appear to take place at a later stage of carcinogenesis.
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Affiliation(s)
- B Bailleul
- Beatson Institute for Cancer Research, Bearsden, Glasgow, UK
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50
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Affiliation(s)
- B Bailleul
- Beatson Institute for Cancer Research, Wolfson Laboratory of Molecular Pathology, Glasgow, UK
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