89 results on '"Sourisseau, M."'
Search Results
2. The ZooCAM, a new in-flow imaging system for fast onboard counting, sizing and classification of fish eggs and metazooplankton
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Colas, F., Tardivel, M., Perchoc, J., Lunven, M., Forest, B., Guyader, G., Danielou, M.M., Le Mestre, S., Bourriau, P., Antajan, E., Sourisseau, M., Huret, M., Petitgas, P., and Romagnan, J.B.
- Published
- 2018
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3. Efficacité d'une stratégie d'utilisation du letermovir basée sur le risque d'infection à CMV chez les patients receveurs d'allogreffe de cellules souches hématopoïétiques
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Sourisseau, M., primary, Faure, E., additional, Faure, K., additional, Béhal, H., additional, Yakoub-agha, I., additional, and Beauvais, D., additional
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- 2022
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4. P1324: A RISK-BASED STRATEGY FOR THE USE OF LETERMOVIR IN CMV-POSITIVE RECIPIENTS OF ALLOGENEIC HEMATOPOIETIC CELL TRANSPLANTATION
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Beauvais, D., primary, Sourisseau, M., additional, Béhal, H., additional, Alfandari, S., additional, Simon, N., additional, Faure, E., additional, and Yakoub-Agha, I., additional
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- 2022
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5. Novel Methodologies for Providing In Situ Data to HAB Early Warning Systems in the European Atlantic Area: The PRIMROSE Experience
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Ruiz-Villarreal, Manuel, Sourisseau, M., Anderson, P., Cusack, C., Neira, P., Silke, J., Rodríguez Hernández, Francisco José, Ben-Gigirey, Begoña, Whyte, C., Giraudeau-Potel, S., Quemener, L., Arthur, G., Davidson, K., Ruiz-Villarreal, Manuel, Sourisseau, M., Anderson, P., Cusack, C., Neira, P., Silke, J., Rodríguez Hernández, Francisco José, Ben-Gigirey, Begoña, Whyte, C., Giraudeau-Potel, S., Quemener, L., Arthur, G., and Davidson, K.
- Abstract
Harmful algal blooms (HABs) cause harm to human health or hinder sustainable use of the marine environment in Blue Economy sectors. HABs are temporally and spatially variable and hence their mitigation is closely linked to effective early warning. The European Union (EU) Interreg Atlantic Area project “PRIMROSE”, Predicting Risk and Impact of Harmful Events on the Aquaculture Sector, was focused on the joint development of HAB early warning systems in different regions along the European Atlantic Area. Advancement of the existing HAB forecasting systems requires development of forecasting tools, improvements in data flow and processing, but also additional data inputs to assess the distribution of HAB species, especially in areas away from national monitoring stations, usually located near aquaculture sites. In this contribution, we review different novel technologies for acquiring HAB data and report on the experience gained in several novel local data collection exercises performed during the project. Demonstrations include the deployment of autonomous imaging flow cytometry (IFC) sensors near two aquaculture areas: a mooring in the Daoulas estuary in the Bay of Brest and pumping from a bay in the Shetland Islands to an inland IFC; and several drone deployments, both of Unmanned Aerial Vehicles (UAV) and of Autonomous Surface vehicles (ASVs). Additionally, we have reviewed sampling approaches potentially relevant for HAB early warning including protocols for opportunistic water sampling by coastguard agencies. Experiences in the determination of marine biotoxins in non-traditional vectors and how they could complement standard routine HAB monitoring are also considered.
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- 2022
6. Comparative mapping of protein-protein interactions between tick-borne flaviviruses and their mammalian hosts reveals virus and mammalian host-specific interactions
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Sourisseau, M, Lemasson, M, Unterfinger, Y, Caignard, G, Piumi, F, Grot, A, Moutailler, S, Johnson, N, Vitour, D, Estrada-Peña, A, Jouvenet, N, Coulpier, M, Lacour, Sa, Richardson, Jp, and Moutailler, Sara
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[SDV] Life Sciences [q-bio] ,ticks - Published
- 2022
7. Identification of candidate molecular determinants of the vector competence of Ixodes ricinus for members of the tick-borne encephalitis virus complex
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Lemasson, M, Petit, M, Sourisseau, M, Caignard, G, Unterfinger, Y, Attoui, H, Bell-Sakyi, L, Moutailler, S, Simo, L, Johnson, N, Vitour, D, Saleh, Mc, Richardson, J, Lacour, Sa, and Moutailler, Sara
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[SDV] Life Sciences [q-bio] ,ticks - Published
- 2022
8. Krill aggregation in the St. Lawrence system, and supply of krill to the whale feeding grounds in the estuary from the gulf
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Sourisseau, M., Simard, Y., and Saucier, F. J.
- Published
- 2006
9. Alexandrium minutum growth controlled by phosphorus : An applied model
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Chapelle, A., Labry, C., Sourisseau, M., Lebreton, C., Youenou, A., and Crassous, M.P.
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- 2010
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10. Changes in community assembly during the development of a thin layer of phytoplankton
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Velasco-Senovilla, E (Esther), Reguera, B. (Beatriz), Ramilo-Rivero, M.I. (María Isabel), Casas-Rodríguez, G. (Gerardo), Fernández-Carrera, G. (Gerardo), Mouriño-Carballido, B. (Beatriz), Gilcoto, M. (Miguel), Broullón, E. (Esperanza), Fernández-Castro, B. (Bieito), Sourisseau, M. (Marc), Jauzein, C. (Cecile), and Nogueira, E. (Enrique)
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habitat conditions ,phytoplankton ,community assembly - Published
- 2021
11. Phytoplankton taxonomic and functional diversity patterns across a coastal tidal front
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Ramond, P., Siano, R., Schmitt, S., de Vargas, C., Marié, L., Memery, L., Sourisseau, M., Ramond, P., Siano, R., Schmitt, S., de Vargas, C., Marié, L., Memery, L., and Sourisseau, M.
- Abstract
Oceanic physics at fine scale; e.g. eddies, fronts, filaments; are notoriously difficult to sample. However, an increasing number of theoretical approaches hypothesize that these processes affect phytoplankton diversity which have cascading effects on regional ecosystems. In 2015, we targeted the Iroise Sea (France) and evidenced the setting up of the Ushant tidal front from the beginning of spring to late summer. Seawater samples were taken during three sampling cruises and DNA-barcoding allowed us to investigate patterns of eukaryotic phytoplankton diversity across this front. First focusing on patterns of taxonomic richness, we evidenced that the front harbored a hotspot of eukaryotic phytoplankton diversity sustained throughout summer. We then detail the ecological processes leading to the formation of this hotspot by studying shifts in community composition across the Iroise Sea. Physical mixing mingled the communities surrounding the front, allowing the formation of a local ecotone, but it was cycles of disturbances and nutrient inputs over the front that allowed a decrease in competitive exclusion, which maintained a higher diversity of rare phytoplankton taxa. These processes did not select a specific ecological strategy as inferred by a trait approach coupled to our taxonomic approach. Instead the front favored higher richness within widespread strategies, resulting in functional redundancy. We detail how fine-scale ocean physics affect phytoplankton diversity and suppose that this interplay is a major control on regional ecosystems.
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- 2021
12. Krill diel vertical migration fine dynamics, nocturnal overturns, and their roles for aggregation in stratified flows
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Sourisseau, M., Simard, Y., and Saucier, F.J.
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Animal migration -- Observations ,Krill -- Behavior ,Earth sciences - Abstract
Abstract: A set of high-resolution observations on short-term dynamics of krill diel vertical migrations (DVM) in the St. Lawrence Estuary are presented here, including vertical mass transfer measurements from multifrequency [...]
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- 2008
13. Inventory and access to data for Predicting Risk and Impact of Harmful Events on the Aquaculture Sector (PRIMROSE Deliverable 4.1)
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Miller, Peter I., Sourisseau, M. (Marc), Davidson, K. (Keith), Aleynik, D., Neira, P., Clarke, D., Ferrer, L., Ruiz-Villarreal, M. (Manuel), García-García, L. (Luz), González-Nuevo, G. (Gonzalo), Kurekin, A.A., Clements, O., and Bedington, M.
- Published
- 2020
14. P10-04. Mechanisms of HIV-1 detection by plasmacytoid dendritic cells
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Albert M, Mammano F, Perrin V, Sourisseau M, Louis S, Lepelley A, and Schwartz O
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Immunologic diseases. Allergy ,RC581-607 - Published
- 2009
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15. Advancing observation of ocean biogeochemistry, biology, and ecosystems with cost-effective in situ sensing technologies
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Wang, Z. A., Moustahfid, H., Mueller, A. V., Michel, A. P. M., Mowlem, M., Glazer, B. T., Mooney, T. A., Michaels, W., McQuillan, J. S., Robidart, J. C., Churchill, J., Sourisseau, M., Daniel, A., Schaap, A., Monk, S., Friedman, K., and Brehmer, Patrice
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OceanObs ,EOVs ,sensor ,biogeochemistry ,biology ,cost effective ,in situ ,ocean technology - Abstract
Advancing our understanding of ocean biogeochemistry, biology, and ecosystems relies on the ability to make observations both in the ocean and at the critical boundaries between the ocean and other earth systems at relevant spatial and temporal scales. After decades of advancement in ocean observing technologies, one of the key remaining challenges is how to cost-effectively make measurements at the increased resolution necessary for illuminating complex system processes and rapidly evolving changes. In recent years, biogeochemical in situ sensors have been emerging that are threefold or more lower in cost than established technologies; the cost reduction for many biological in situ sensors has also been significant, although the absolute costs are still relatively high. Cost savings in these advancements has been driven by miniaturization, new methods of packaging, and lower-cost mass-produced components such as electronics and materials. Recently, field projects have demonstrated the potential for science-quality data collection via large-scale deployments using cost-effective sensors and deployment strategies. In the coming decade, it is envisioned that ocean biogeochemistry and biology observations will be revolutionized by continued innovation in sensors with increasingly low price points and the scale-up of deployments of these in situ sensor technologies. The goal of this study is therefore to: (1) provide a review of existing sensor technologies that are already achieving cost-effectiveness compared with traditional instrumentation, (2) present case studies of cost-effective in situ deployments that can provide insight into methods for bridging observational gaps, (3) identify key challenge areas where progress in cost reduction is lagging, and (4) present a number of potentially transformative directions for future ocean biogeochemical and biological studies using cost-effective technologies and deployment strategies.
- Published
- 2019
16. Resource Competition Affects Plankton Community Structure; Evidence from Trait-Based Modeling
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Sourisseau, M, Le Guennec, V, Le Gland, G, Plus, M, and Chapelle, A
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Niches ,Competition ,Phenology ,Alexandrium minutum ,Estuary ,Bay of Brest ,Droop ,Marine Science ,Inter-specific - Abstract
14 pages, 8 figures, 6 tables, Understanding the phenology of phytoplankton species is a challenge and despite a lot of theoretical work on competition for resources, this process is under-represented in deterministic models. To study the main driver of the species selection, we used a trait-based model that keeps phenotypic variability through physiological trait parameterization. Next, we validated the results by using the toxic dinoflagellate Alexandrium minutum which is a toxic species. Due to their monitoring, we show that harmful algae are ideal models for studying ecological niches and for contributing to this more global challenge. As a first step, a dimensionless model of an estuary (France) was built with water temperature and water exchanges deduced from a hydro-dynamic model. The biological parametrization takes into account the size (from pico- to microphytoplankton) and the type of assimilation. The results show that temperature, competition for nutrients and dilution are important factors regulating the community structure and Alexandrium minutum dynamics (more especially the bloom initiation and magnitude). These drivers contribute to the determination of the ecological niche of A. minutum, influence the shape of its blooms and provide potential explanations of its interannual variability. This approach makes the community structure more flexible in order to study how environmental forcings could drive its evolution, The project was supported by the Agence de l’Eau Loire Bretagne and the Region Bretagne (Daoulex project)
- Published
- 2017
17. Assessing spatial and temporal variability of phytoplankton communities' composition in the Iroise Sea ecosystem (Brittany, France) : a 3D modeling approach. Part 1 : Biophysical control over plankton functional types succession and distribution
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Cadier, M., Gorgues, Thomas, Sourisseau, M., Edwards, C. A., Aumont, Olivier, Marie, L., and Memery, L.
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Biogeochemical modeling ,fungi ,Phytoplankton ,Functional groups ,Tidal mixing front ,Seasonal cycle ,Iroise Sea - Abstract
Understanding the dynamic interplay between physical, biogeochemical and biological processes represents a key challenge in oceanography, particularly in shelf seas where complex hydrodynamics are likely to drive nutrient distribution and niche partitioning of phytoplankton communities. The Iroise Sea includes a tidal front called the 'Ushant Front' that undergoes a pronounced seasonal cycle, with a marked signal during the summer. These characteristics as well as relatively good observational sampling make it a region of choice to study processes impacting phytoplankton dynamics. This innovative modeling study employs a phytoplankton-diversity model, coupled to a regional circulation model to explore mechanisms that alter biogeography of phytoplankton in this highly dynamic environment. Phytoplankton assemblages are mainly influenced by the depth of the mixed layer on a seasonal time scale. Indeed, solar incident irradiance is a limiting resource for phototrophic growth and small phytoplankton cells are advantaged over larger cells. This phenomenon is particularly relevant when vertical mixing is intense, such as during winter and early spring. Relaxation of wind-induced mixing in April causes an improvement of irradiance experienced by cells across the whole study area. This leads, in late spring, to a competitive advantage of larger functional groups such as diatoms as long as the nutrient supply is sufficient. This dominance of large, fast-growing autotrophic cells is also maintained during summer in the productive tidally-mixed shelf waters. In the oligotrophic surface layer of the western part of the Iroise Sea, small cells coexist in a greater proportion with large, nutrient limited cells. The productive Ushant tidal front's region (1800 mgC.m(-2).d(-1) between August and September) is also characterized by a high degree of coexistence between three functional groups (diatoms, micro/nano-flagellates and small eukaryotes/cyanobacteria). Consistent with previous studies, the biogeography of phytoplankton functional types at the Ushant front during summer displays an intermediate community composition between contrasted sub-regions on either side of the front. Strong mixing conditions within the frontal sub-region result in a short residence time of water masses, not allowing speciation or long term adaptation to occur.
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- 2017
18. Distribution and dynamics of two species of Dinophyceae producing high biomass blooms over the French Atlantic Shelf
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Sourisseau, M., primary, Jegou, K., additional, Lunven, M., additional, Quere, J., additional, Gohin, F., additional, and Bryere, P., additional
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- 2016
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19. Oceanographic settings associated with interannual variabilityin the initiation of Dinophysis blooms
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Díaz, P.A. (Patricio Andrés), Reguera, B. (Beatriz), Escalera-Moura, L. (Laura), Pazos, Y. (Yolanda), Varela, M., Sourisseau, M. (Marc), Daniélou, M.M., and Ruiz-Villarreal, M. (Manuel)
- Published
- 2013
20. Spatial and vertical distribution of springtime zooplankton over the western European shelf and slope from Galician coast to Ushant front
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Vandromme, P. (Pieter), Nogueira, E. (Enrique), Huret, M. (Martin), González-Nuevo, G. (Gonzalo), López-Urrutia-Lorente, Á. (Ángel), Sourisseau, M. (Marc), and Petitgas, P.
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Medio Marino ,Centro Oceanográfico de Gijón - Published
- 2012
21. Innate sensing of HIV-infected cells
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4.Lepelley A, Louis S, Sourisseau M, Law HK, Pothlichet J, Schilte C, Chaperot L, Plumas J, Randall RE, Si-Tahar M, Mammano F, Albert ML, and Schwartz O
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- 2011
22. ASIMUTH: Applied simulations and integrated modelling for the understanding of toxic and harmful algal blooms
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Silke, J. (Joe), Nolan, G., Gentien, P. (Patrick), Sourisseau, M. (Marc), Lazure, P. (Pascal), Reguera, B. (Beatriz), Ruiz-Villarreal, M. (Manuel), Velo-Suárez, L. (Lourdes), Davidson, K. (Keith), Dale, A., Lefouest, V., Neves, R., Mateus, Marcos, Moita, T., Palma, S., Silva, A., Rodrigues, S., Delmas, R., Bryère, P. (Philippe), Jouan, M., White, M., Nash, K., Jarocki, A., Moreno, L., Romero-Méndez, L. (Luis), Figueroa, P., Curé, M., and Maguire, J.
- Published
- 2010
23. Springtime zooplankton size structure over the continental shelf of the Bay of Biscay
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Vandromme, P., primary, Nogueira, E., additional, Huret, M., additional, Lopez-Urrutia, Á., additional, González-Nuevo González, G., additional, Sourisseau, M., additional, and Petitgas, P., additional
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- 2014
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24. Spring-time zooplankton size structure over the continental shelf of the Bay of Biscay
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Vandromme, P., primary, Nogueira, E., additional, Huret, M., additional, Lopez-Urrutia, Á, additional, González-Nuevo González, G., additional, Sourisseau, M., additional, and Petitgas, P., additional
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- 2013
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25. Un an après la dévaluation, les producteurs sont dans l'expectative
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Benz, Hélène, Fusillier, Jean-Louis, Hassane, S., Liagre, Laurent, Mendez Del Villar, Patricio, and Sourisseau, M.
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Prix ,Dévaluation ,Périmètre irrigué ,E13 - Investissements, financement et crédit ,Économie ,riz - Abstract
Cette étude, menée par des économistes du CIRAD, a pour but d'analyser les répercussions de la dévaluation du franc CFA : d'une part sur le prix de revient du riz irrigué dans les grands aménagements hydrauliques (et sur sa compétitivité vis-à-vis du riz d'importation) et d'autre part sur le comportement des divers opérateurs de la filière. Il semble, malgré des conclusions prudemment nuancées, que cette opération financière n'a guère changé les pratiques des riziculteurs, dans un secteur qui évolue avec le désengagement de l'Etat et la libération des prix
- Published
- 1995
26. P10-04. Mechanisms of HIV-1 detection by plasmacytoid dendritic cells
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Lepelley, A, primary, Louis, S, additional, Sourisseau, M, additional, Perrin, V, additional, Mammano, F, additional, Albert, M, additional, and Schwartz, O, additional
- Published
- 2009
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27. Corrigendum: Krill diel vertical migration fine dynamics, nocturnal overturns, and their roles for aggregation in stratified flows
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Sourisseau, M., primary, Simard, Y., additional, and Saucier, F. J., additional
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- 2009
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28. Spring-time zooplankton size structure over the continental shelf of the Bay of Biscay.
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Vandromme, P., Nogueira, E., Huret, M., Lopez-Urrutia, Á., González, G. González-Nuevo, Sourisseau, M., and Petitgas, P.
- Subjects
ZOOPLANKTON ,INFORMATION theory ,BIOLOGICAL models ,STATISTICS ,PELAGE - Abstract
Linking lower to higher trophic levels requires a special focus on the pivotal role played by mid-trophic levels, i.e. the zooplankton. One of the most relevant information on zooplankton in term of fluxes of matter lies in its size structure. We present here an extensive dataset of size measurements covering part of the western European shelf and slope, from the Galician coast to the Ushant front, during springs from 2005 to 2012. Zooplankton size spectra were estimated using both measurements carried out in situ by the Laser-Optical Plankton Counter (LOPC, 816 records) and WP2 net (200 µm mesh size) samples scanned following the ZooScan methodology and image analysis (a total of 89 samples were analyzed). The LOPC counts and sizes all particles in the range 100 to 2000 µm of spherical equivalent diameter (ESD) whereas the WP2/ZooScan allows the counting, sizing and identification of zooplankton from 400 µm ESD. The difference between the LOPC (all particles) and the WP2/ZooScan (zooplankton only) is assumed to provide the size distribution of non-living particles whose descriptors are further related to a set of explanatory variables (including physical, biological and geographic descriptors). A statistical correction based on these explanatory variables is then applied to LOPC measurements to removed the part due to non-living particles and estimate zooplankton size spectra. This extensive data set provides a new look at regional and inter-annual variability of the pelagic ecosystem of the Bay of Biscay. [ABSTRACT FROM AUTHOR]
- Published
- 2013
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29. Roles of epidermal growth factor receptor, claudin-1 and occludin in multi-step entry of hepatitis C virus into polarized hepatoma spheroids.
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So CW, Sourisseau M, Sarwar S, Evans MJ, and Randall G
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- Humans, Carcinoma, Hepatocellular metabolism, Carcinoma, Hepatocellular pathology, Clathrin, ErbB Receptors, Occludin metabolism, Virus Internalization, Claudin-1 genetics, Claudin-1 metabolism, Hepacivirus physiology, Hepatitis C metabolism, Liver Neoplasms metabolism, Liver Neoplasms pathology
- Abstract
The multi-step process of hepatitis C virus (HCV) entry is facilitated by various host factors, including epidermal growth factor receptor (EGFR) and the tight junction proteins claudin-1 (CLDN1) and occludin (OCLN), which are thought to function at later stages of the HCV entry process. Using single particle imaging of HCV infection of polarized hepatoma spheroids, we observed that EGFR performs multiple functions in HCV entry, both phosphorylation-dependent and -independent. We previously observed, and in this study confirmed, that EGFR is not required for HCV migration to the tight junction. EGFR is required for the recruitment of clathrin to HCV in a phosphorylation-independent manner. EGFR phosphorylation is required for virion internalization at a stage following the recruitment of clathrin. HCV entry activates the RAF-MEK-ERK signaling pathway downstream of EGFR phosphorylation. This signaling pathway regulates the sorting and maturation of internalized HCV into APPL1- and EEA1-associated early endosomes, which form the site of virion uncoating. The tight junction proteins, CLDN1 and OCLN, function at two distinct stages of HCV entry. Despite its appreciated function as a "late receptor" in HCV entry, CLDN1 is required for efficient HCV virion accumulation at the tight junction. Huh-7.5 cells lacking CLDN1 accumulate HCV virions primarily at the initial basolateral surface. OCLN is required for the late stages of virion internalization. This study produced further insight into the unusually complex HCV endocytic process., Competing Interests: The authors have declared that no competing interests exist., (Copyright: © 2023 So et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.)
- Published
- 2023
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30. Tick-borne flavivirus NS5 antagonizes interferon signaling by inhibiting the catalytic activity of TYK2.
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Gracias S, Chazal M, Decombe A, Unterfinger Y, Sogues A, Pruvost L, Robert V, Lacour SA, Lemasson M, Sourisseau M, Li Z, Richardson J, Pellegrini S, Decroly E, Caval V, and Jouvenet N
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- Interferons metabolism, Viral Nonstructural Proteins genetics, Viral Nonstructural Proteins metabolism, Humans, Encephalitis Viruses, Tick-Borne genetics, Encephalitis Viruses, Tick-Borne metabolism, Ticks metabolism, TYK2 Kinase metabolism
- Abstract
The mechanisms utilized by different flaviviruses to evade antiviral functions of interferons are varied and incompletely understood. Using virological approaches, biochemical assays, and mass spectrometry analyses, we report here that the NS5 protein of tick-borne encephalitis virus (TBEV) and Louping Ill virus (LIV), two related tick-borne flaviviruses, antagonize JAK-STAT signaling through interactions with the tyrosine kinase 2 (TYK2). Co-immunoprecipitation (co-IP) experiments, yeast gap-repair assays, computational protein-protein docking and functional studies identify a stretch of 10 residues of the RNA dependent RNA polymerase domain of tick-borne flavivirus NS5, but not mosquito-borne NS5, that is critical for interactions with the TYK2 kinase domain. Additional co-IP assays performed with several TYK2 orthologs reveal that the interaction is conserved across mammalian species. In vitro kinase assays show that TBEV and LIV NS5 reduce the catalytic activity of TYK2. Our results thus illustrate a novel mechanism by which viruses suppress the interferon response., (© 2023 The Authors.)
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- 2023
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31. Assembly processes and functional diversity of marine protists and their rare biosphere.
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Ramond P, Siano R, Sourisseau M, and Logares R
- Abstract
Background: The mechanisms shaping the rare microbial biosphere and its role in ecosystems remain unclear. We developed an approach to study ecological patterns in the rare biosphere and use it on a vast collection of marine microbiomes, sampled in coastal ecosystems at a regional scale. We study the assembly processes, and the ecological strategies constituting the rare protistan biosphere. Using the phylogeny and morpho-trophic traits of these protists, we also explore their functional potential., Results: Taxonomic community composition remained stable along rank abundance curves. Conditionally rare taxa, driven by selection processes, and transiently rare taxa, with stochastic distributions, were evidenced along the rank abundance curves of all size-fractions. Specific taxa within the divisions Sagenista, Picozoa, Telonemia, and Choanoflagellida were rare across time and space. The distribution of traits along rank abundance curves outlined a high functional redundancy between rare and abundant protists. Nevertheless, trophic traits illustrated an interplay between the trophic groups of different size-fractions., Conclusions: Our results suggest that rare and abundant protists are evolutionary closely related, most notably due to the high microdiversity found in the rare biosphere. We evidenced a succession of assembly processes and strategies of rarity along rank abundance curves that we hypothesize to be common to most microbiomes at the regional scale. Despite high functional redundancy in the rare protistan biosphere, permanently rare protists were evidenced, and they could play critical functions as bacterivores and decomposers from within the rare biosphere. Finally, changes in the composition of the rare protistan biosphere could be influenced by the trophic regime of aquatic ecosystems. Our work contributes to understanding the role of rare protists in microbiomes., (© 2023. The Author(s).)
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- 2023
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32. [Cell hijacking by a tick-borne flavivirus: dangerous linkages between viral RNA and cellular proteins in humans and the tick Ixodes ricinus].
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Grot A, Unterfinger Y, Lacour S, Bell-Sakyi L, Attoui H, Richardson J, and Sourisseau M
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- Animals, Humans, RNA, Viral, Ixodes genetics, Encephalitis Viruses, Tick-Borne genetics
- Published
- 2023
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33. The promising efficacy of a risk-based letermovir use strategy in CMV-positive allogeneic hematopoietic cell recipients.
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Sourisseau M, Faure E, Béhal H, Chauvet P, Srour M, Capes A, Coiteux V, Magro L, Alfandari S, Alidjinou EK, Simon N, Vuotto F, Karam M, Faure K, Yakoub-Agha I, and Beauvais D
- Subjects
- Adult, Humans, Antiviral Agents adverse effects, Cytomegalovirus, Cytomegalovirus Infections drug therapy, Cytomegalovirus Infections etiology, Cytomegalovirus Infections prevention & control, Hematopoietic Stem Cell Transplantation adverse effects
- Abstract
Letermovir is the first approved drug for cytomegalovirus (CMV) infection prophylaxis in adult patients who are CMV positive undergoing allogeneic hematopoietic cell transplantation (allo-HCT). Because CMV infection risk varies from patient to patient, we evaluated whether a risk-based strategy could be effective. In this single-center study, all consecutive adult patients who were CMV positive and underwent allo-HCT between 2015 and 2021 were included. During period 1 (2015-2017), letermovir was not used, whereas during period 2 (2018-2021), letermovir was used in patients at high risk but not in patients at low risk, except in those receiving corticosteroids. In patients at high risk, the incidence of clinically significant CMV infection (csCMVi) in period 2 was lower than that in period 1 (P < .001) by week 14 (10.5% vs 51.6%) and week 24 (16.9% vs 52.7%). In patients at low risk, although only 28.6% of patients received letermovir in period 2, csCMVi incidence was also significantly lower (P = .003) by week 14 (7.9% vs 29.0%) and week 24 (11.2% vs 33.3%). Among patients at low risk who did not receive letermovir (n = 45), 23 patients (51.1%) experienced transient positive CMV DNA without csCMVi, whereas 17 patients (37.8%) experienced negative results. In both risk groups, the 2 periods were comparable for CMV disease, overall survival, progression-free survival, relapse, and nonrelapse mortality. We concluded that a risk-based strategy for letermovir use is an effective strategy which maintains the high efficacy of letermovir in patients at high risk but allows some patients at low risk to not use letermovir., (© 2023 by The American Society of Hematology. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0), permitting only noncommercial, nonderivative use with attribution. All other rights reserved.)
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- 2023
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34. Strong population genomic structure of the toxic dinoflagellate Alexandrium minutum inferred from meta-transcriptome samples.
- Author
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Le Gac M, Mary L, Metegnier G, Quéré J, Siano R, Rodríguez F, Destombe C, and Sourisseau M
- Subjects
- Transcriptome, Metagenomics, Gene Flow, Population Density, Dinoflagellida genetics
- Abstract
Despite theoretical expectations, marine microeukaryote population are often highly structured and the mechanisms behind such patterns remain to be elucidated. These organisms display huge census population sizes, yet genotyping usually requires clonal strains originating from single cells, hindering proper population sampling. Estimating allelic frequency directly from population wide samples, without any isolation step, offers an interesting alternative. Here, we validate the use of meta-transcriptome environmental samples to determine the population genetic structure of the dinoflagellate Alexandrium minutum. Strain and meta-transcriptome based results both indicated a strong genetic structure for A. minutum in Western Europe, to the level expected between cryptic species. The presence of numerous private alleles, and even fixed polymorphism, would indicate ancient divergence and absence of gene flow between populations. Single nucleotide polymorphisms (SNPs) displaying strong allele frequency differences were distributed throughout the genome, which might indicate pervasive selection from standing genetic variation (soft selective sweeps). However, a few genomic regions displayed extremely low diversity that could result from the fixation of adaptive de novo mutations (hard selective sweeps) within the populations., (© 2022 Applied Microbiology International and John Wiley & Sons Ltd.)
- Published
- 2022
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35. Pelagic diatoms communicate through synchronized beacon natural fluorescence signaling.
- Author
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Font-Muñoz JS, Sourisseau M, Cohen-Sánchez A, Tuval I, and Basterretxea G
- Abstract
Communication between conspecific individuals is an essential part of life both in terrestrial and marine realms. Until recently, social behavior in marine phytoplankton was assumed to rely mainly on the secretion of a variety of infochemicals that allowed population-scale collective responses. Here, we demonstrate that pelagic diatoms also use Sun-stimulated fluorescence signals for synchronizing their behavior. These unicellular microorganisms, playing a key biogeochemical role in the ocean, use photoreceptor proteins and red–far-red fluorescent radiation to communicate. A characteristic beaconing signal is generated by rhythmic organelle displacement within the cell cytoplasm, triggering coordinated population behavior. These light-based communication networks could critically determine major facets of diatom ecology and fitness and regulate the dynamics of larger-scale ocean processes.
- Published
- 2021
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36. Current distribution and potential expansion of the harmful benthic dinoflagellate Ostreopsis cf. siamensis towards the warming waters of the Bay of Biscay, North-East Atlantic.
- Author
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Drouet K, Jauzein C, Herviot-Heath D, Hariri S, Laza-Martinez A, Lecadet C, Plus M, Seoane S, Sourisseau M, Lemée R, and Siano R
- Subjects
- Bays, Temperature, Dinoflagellida genetics
- Abstract
In a future scenario of increasing temperatures in North-Atlantic waters, the risk associated with the expansion of the harmful, benthic dinoflagellate Ostreopsis cf. siamensis has to be evaluated and monitored. Microscopy observations and spatio-temporal surveys of environmental DNA (eDNA) were associated with Lagrangian particle dispersal simulations to: (i) establish the current colonization of the species in the Bay of Biscay, (ii) assess the spatial connectivity among sampling zones that explain this distribution, and (iii) identify the sentinel zones to monitor future expansion. Throughout a sampling campaign carried out in August to September 2018, microscope analysis showed that the species develops in the south-east of the bay where optimal temperatures foster blooms. Quantitative PCR analyses revealed its presence across almost the whole bay to the western English Channel. An eDNA time-series collected on plastic samplers showed that the species occurs in the bay from April to September. Due to the water circulation, colonization of the whole bay from the southern blooming zones is explained by inter-site connectivity. Key areas in the middle of the bay permit continuous dispersal connectivity towards the north. These key areas are proposed as sentinel zones to monitor O. cf. siamensis invasions towards the presumably warming water of the North-East Atlantic., (© 2021 Society for Applied Microbiology and John Wiley & Sons Ltd.)
- Published
- 2021
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37. Dinophyceae can use exudates as weapons against the parasite Amoebophrya sp. (Syndiniales).
- Author
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Long M, Marie D, Szymczak J, Toullec J, Bigeard E, Sourisseau M, Le Gac M, Guillou L, and Jauzein C
- Abstract
Parasites in the genus Amoebophrya sp. infest dinoflagellate hosts in marine ecosystems and can be determining factors in the demise of blooms, including toxic red tides. These parasitic protists, however, rarely cause the total collapse of Dinophyceae blooms. Experimental addition of parasite-resistant Dinophyceae (Alexandrium minutum or Scrippsiella donghaienis) or exudates into a well-established host-parasite coculture (Scrippsiella acuminata-Amoebophrya sp.) mitigated parasite success and increased the survival of the sensitive host. This effect was mediated by waterborne molecules without the need for a physical contact. The strength of the parasite defenses varied between dinoflagellate species, and strains of A. minutum and was enhanced with increasing resistant host cell concentrations. The addition of resistant strains or exudates never prevented the parasite transmission entirely. Survival time of Amoebophrya sp. free-living stages (dinospores) decreased in presence of A. minutum but not of S. donghaienis. Parasite progeny drastically decreased with both species. Integrity of the dinospore membrane was altered by A. minutum, providing a first indication on the mode of action of anti-parasitic molecules. These results demonstrate that extracellular defenses can be an effective strategy against parasites that protects not only the resistant cells producing them, but also the surrounding community., (© 2021. The Author(s).)
- Published
- 2021
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38. Phytoplankton taxonomic and functional diversity patterns across a coastal tidal front.
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Ramond P, Siano R, Schmitt S, de Vargas C, Marié L, Memery L, and Sourisseau M
- Abstract
Oceanic physics at fine scale; e.g. eddies, fronts, filaments; are notoriously difficult to sample. However, an increasing number of theoretical approaches hypothesize that these processes affect phytoplankton diversity which have cascading effects on regional ecosystems. In 2015, we targeted the Iroise Sea (France) and evidenced the setting up of the Ushant tidal front from the beginning of spring to late summer. Seawater samples were taken during three sampling cruises and DNA-barcoding allowed us to investigate patterns of eukaryotic phytoplankton diversity across this front. First focusing on patterns of taxonomic richness, we evidenced that the front harbored a hotspot of eukaryotic phytoplankton diversity sustained throughout summer. We then detail the ecological processes leading to the formation of this hotspot by studying shifts in community composition across the Iroise Sea. Physical mixing mingled the communities surrounding the front, allowing the formation of a local ecotone, but it was cycles of disturbances and nutrient inputs over the front that allowed a decrease in competitive exclusion, which maintained a higher diversity of rare phytoplankton taxa. These processes did not select a specific ecological strategy as inferred by a trait approach coupled to our taxonomic approach. Instead the front favored higher richness within widespread strategies, resulting in functional redundancy. We detail how fine-scale ocean physics affect phytoplankton diversity and suppose that this interplay is a major control on regional ecosystems.
- Published
- 2021
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39. Species specific gene expression dynamics during harmful algal blooms.
- Author
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Metegnier G, Paulino S, Ramond P, Siano R, Sourisseau M, Destombe C, and Le Gac M
- Subjects
- Atlantic Ocean, DNA Barcoding, Taxonomic, Datasets as Topic, Gene Expression Profiling, Gene Expression Regulation, Ion Channels genetics, Ion Transport genetics, Photosynthesis genetics, Species Specificity, Dinoflagellida genetics, Harmful Algal Bloom physiology, Microbiota genetics
- Abstract
Harmful algal blooms are caused by specific members of microbial communities. Understanding the dynamics of these events requires comparing the strategies developed by the problematic species to cope with environmental fluctuations to the ones developed by the other members of the community. During three consecutive years, the meta-transcriptome of micro-eukaryote communities was sequenced during blooms of the toxic dinoflagellate Alexandrium minutum. The dataset was analyzed to investigate species specific gene expression dynamics. Major shifts in gene expression were explained by the succession of different species within the community. Although expression patterns were strongly correlated with fluctuation of the abiotic environment, and more specifically with nutrient concentration, transcripts specifically involved in nutrient uptake and metabolism did not display extensive changes in gene expression. Compared to the other members of the community, A. minutum displayed a very specific expression pattern, with lower expression of photosynthesis transcripts and central metabolism genes (TCA cycle, glucose metabolism, glycolysis…) and contrasting expression pattern of ion transporters across environmental conditions. These results suggest the importance of mixotrophy, cell motility and cell-to-cell interactions during A. minutum blooms.
- Published
- 2020
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40. Deep Mutational Scanning Comprehensively Maps How Zika Envelope Protein Mutations Affect Viral Growth and Antibody Escape.
- Author
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Sourisseau M, Lawrence DJP, Schwarz MC, Storrs CH, Veit EC, Bloom JD, and Evans MJ
- Subjects
- Amino Acid Sequence, Animals, Antibodies, Monoclonal immunology, Antibodies, Neutralizing, Chlorocebus aethiops, Epitopes immunology, Glycoproteins genetics, Glycoproteins immunology, HEK293 Cells, High-Throughput Nucleotide Sequencing, Humans, Models, Molecular, Protein Conformation, Sequence Alignment, Sequence Analysis, Protein, Vero Cells, Viral Envelope Proteins chemistry, Virus Internalization, Zika Virus growth & development, Zika Virus Infection virology, Antibodies, Viral immunology, Immune Evasion immunology, Mutation, Viral Envelope Proteins genetics, Viral Envelope Proteins immunology, Zika Virus genetics
- Abstract
Functional constraints on viral proteins are often assessed by examining sequence conservation among natural strains, but this approach is relatively ineffective for Zika virus because all known sequences are highly similar. Here, we take an alternative approach to map functional constraints on Zika virus's envelope (E) protein by using deep mutational scanning to measure how all amino acid mutations to the E protein affect viral growth in cell culture. The resulting sequence-function map is consistent with existing knowledge about E protein structure and function but also provides insight into mutation-level constraints in many regions of the protein that have not been well characterized in prior functional work. In addition, we extend our approach to completely map how mutations affect viral neutralization by two monoclonal antibodies, thereby precisely defining their functional epitopes. Overall, our study provides a valuable resource for understanding the effects of mutations to this important viral protein and also offers a roadmap for future work to map functional and antigenic selection to Zika virus at high resolution. IMPORTANCE Zika virus has recently been shown to be associated with severe birth defects. The virus's E protein mediates its ability to infect cells and is also the primary target of the antibodies that are elicited by natural infection and vaccines that are being developed against the virus. Therefore, determining the effects of mutations to this protein is important for understanding its function, its susceptibility to vaccine-mediated immunity, and its potential for future evolution. We completely mapped how amino acid mutations to the E protein affected the virus's ability to grow in cells in the laboratory and escape from several antibodies. The resulting maps relate changes in the E protein's sequence to changes in viral function and therefore provide a valuable complement to existing maps of the physical structure of the protein., (Copyright © 2019 American Society for Microbiology.)
- Published
- 2019
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41. An Influenza Virus Entry Inhibitor Targets Class II PI3 Kinase and Synergizes with Oseltamivir.
- Author
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O'Hanlon R, Leyva-Grado VH, Sourisseau M, Evans MJ, and Shaw ML
- Subjects
- Animals, Cell Line, Chlorocebus aethiops, Class II Phosphatidylinositol 3-Kinases drug effects, Disease Models, Animal, Drug Combinations, Drug Evaluation, Preclinical, Drug Resistance, Viral drug effects, Drug Synergism, ErbB Receptors, Female, Humans, Influenza A Virus, H1N1 Subtype drug effects, Male, Mice, Mice, Inbred BALB C, Vero Cells, Antiviral Agents pharmacology, Enzyme Inhibitors pharmacology, Orthomyxoviridae drug effects, Oseltamivir pharmacology, Phosphatidylinositol 3-Kinases drug effects, Virus Internalization drug effects
- Abstract
Two classes of antivirals targeting the viral neuraminidase (NA) and endonuclease are currently the only clinically useful drugs for the treatment of influenza. However, resistance to both antivirals has been observed in clinical isolates, and there was widespread resistance to oseltamivir (an NA inhibitor) among H1N1 viruses prior to 2009. This potential for resistance and lack of diversity for antiviral targets highlights the need for new influenza antivirals with a higher barrier to resistance. In this study, we identified an antiviral compound, M85, that targets host kinases, epidermal growth factor receptor (EGFR), and phosphoinositide 3 class II β (PIK3C2β) and is not susceptible to resistance by viral mutations. M85 blocks endocytosis of influenza viruses and inhibits a broad-spectrum of viruses with minimal cytotoxicity. In vitro , we found that combinations of M85 and oseltamivir have strong synergism. In the mouse model for influenza, treatment with the combination therapy was more protective against a lethal viral challenge than oseltamivir alone, indicating that development of M85 could lead to combination therapies for influenza. Finally, through this discovery of M85 and its antiviral mechanism, we present the first description of PIK3C2β as a necessary host factor for influenza virus entry.
- Published
- 2019
- Full Text
- View/download PDF
42. Coupling between taxonomic and functional diversity in protistan coastal communities.
- Author
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Ramond P, Sourisseau M, Simon N, Romac S, Schmitt S, Rigaut-Jalabert F, Henry N, de Vargas C, and Siano R
- Subjects
- DNA Barcoding, Taxonomic, Ecology, Eukaryota genetics, Eukaryota isolation & purification, Eukaryota metabolism, Oceans and Seas, Phylogeny, RNA, Ribosomal, 18S genetics, Biodiversity, Eukaryota classification
- Abstract
The study of protistan functional diversity is crucial to understand the dynamics of oceanic ecological processes. We combined the metabarcoding data of various coastal ecosystems and a newly developed trait-based approach to study the link between taxonomic and functional diversity across marine protistan communities of different size-classes. Environmental DNA was extracted and the V4 18S rDNA genomic region was amplified and sequenced. In parallel, we tried to annotate the operational taxonomic units (OTUs) from our metabarcoding dataset to 30 biological traits using published and accessible information on protists. We then developed a method to study trait correlations across protists (i.e. trade-offs) in order to build the best functional groups. Based on the annotated OTUs and our functional groups, we demonstrated that the functional diversity of marine protist communities varied in parallel with their taxonomic diversity. The coupling between functional and taxonomic diversity was conserved across different protist size classes. However, the smallest size-fraction was characterized by wider taxonomic and functional groups diversity, corroborating the idea that nanoplankton and picoplankton are part of a more stable ecological background on which larger protists and metazoans might develop., (© 2019 Society for Applied Microbiology and John Wiley & Sons Ltd.)
- Published
- 2019
- Full Text
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43. Probing Zika Virus Neutralization Determinants with Glycoprotein Mutants Bearing Linear Epitope Insertions.
- Author
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Chambers MT, Schwarz MC, Sourisseau M, Gray ES, and Evans MJ
- Subjects
- Animals, Antibodies, Neutralizing chemistry, Antibodies, Neutralizing metabolism, Binding Sites, Antibody genetics, Binding Sites, Antibody immunology, Chlorocebus aethiops, Epitopes chemistry, Epitopes genetics, Epitopes immunology, Glycosylation, Humans, Immunity, Humoral, Membrane Glycoproteins genetics, Mutagenesis, Insertional, Neutralization Tests, Vero Cells, Zika Virus chemistry, Zika Virus immunology, Antibodies, Neutralizing immunology, Membrane Glycoproteins immunology, Mutation, Viral Envelope Proteins immunology, Zika Virus genetics
- Abstract
Zika virus (ZIKV) glycoproteins are the primary target of the humoral immune response. In this study, we explored the capacity of these glycoproteins to tolerate insertion of linear epitope sequences and the potential of antibodies that bind these epitopes to inhibit infection. We first created a panel of ZIKV mutants with the FLAG epitope inserted in the premembrane (prM) and envelope (E) glycoprotein regions. The insertion locations were based on the results of our recent transposon insertional mutagenesis screen. Although FLAG insertions in prM greatly impaired viral fitness, this sequence was tolerated in numerous surface-exposed E protein sites. We observed that mutants bearing FLAG epitopes in E domains I and II and the E domain I-II hinge region were all neutralized by FLAG antibody; however, the neutralization sensitivity varied highly. We measured the antibody binding efficiency and found that this closely matched the pattern of neutralization sensitivity. We determined that E glycosylation did not affect antibody binding to a nearby epitope or its capacity to serve as a neutralization target. Although we could not generate infectious viruses with FLAG epitope insertions in a buried region of E protein domain III, we found that the V5 epitope could be inserted at this site without greatly impacting fitness. Furthermore, this virus was efficiently neutralized by V5 antibodies, highlighting that even buried epitopes can function as neutralization targets. Finally, we analyzed the timing of antibody neutralization activity during cell entry and found that all antibodies blocked a step after cell attachment. IMPORTANCE Zika virus (ZIKV) infections are associated with severe birth defects and neurological disease. The structure of the mature ZIKV particle reveals a virion surface covered by the envelope glycoprotein, which is the dominant target of the humoral immune response. It is unclear if all regions of the envelope protein surface or even buried epitopes can function as neutralization targets. To test this, we created a panel of ZIKV mutants with epitope insertions in different regions of the envelope protein. In characterizing these viruses, we found that the strength of antibody binding to an epitope is the major determinant of the neutralization potential of an antibody, that even a buried region of the envelope protein can be efficiently targeted, and that the sole potential envelope glycan does not impact nearby epitope antibody binding and neutralization. Furthermore, this work provides important insights into our understanding of how antibodies neutralize ZIKV., (Copyright © 2018 American Society for Microbiology.)
- Published
- 2018
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- View/download PDF
44. A novel Zika virus mouse model reveals strain specific differences in virus pathogenesis and host inflammatory immune responses.
- Author
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Tripathi S, Balasubramaniam VR, Brown JA, Mena I, Grant A, Bardina SV, Maringer K, Schwarz MC, Maestre AM, Sourisseau M, Albrecht RA, Krammer F, Evans MJ, Fernandez-Sesma A, Lim JK, and García-Sastre A
- Subjects
- Animals, Inflammation immunology, Inflammation virology, Mice, Mice, Inbred C57BL, Mice, Knockout, Phylogeny, Real-Time Polymerase Chain Reaction, Zika Virus genetics, Disease Models, Animal, Zika Virus immunology, Zika Virus pathogenicity, Zika Virus Infection immunology
- Abstract
Zika virus (ZIKV) is a mosquito borne flavivirus, which was a neglected tropical pathogen until it emerged and spread across the Pacific Area and the Americas, causing large human outbreaks associated with fetal abnormalities and neurological disease in adults. The factors that contributed to the emergence, spread and change in pathogenesis of ZIKV are not understood. We previously reported that ZIKV evades cellular antiviral responses by targeting STAT2 for degradation in human cells. In this study, we demonstrate that Stat2-/- mice are highly susceptible to ZIKV infection, recapitulate virus spread to the central nervous system (CNS), gonads and other visceral organs, and display neurological symptoms. Further, we exploit this model to compare ZIKV pathogenesis caused by a panel of ZIKV strains of a range of spatiotemporal history of isolation and representing African and Asian lineages. We observed that African ZIKV strains induce short episodes of severe neurological symptoms followed by lethality. In comparison, Asian strains manifest prolonged signs of neuronal malfunctions, occasionally causing death of the Stat2-/- mice. African ZIKV strains induced higher levels of inflammatory cytokines and markers associated with cellular infiltration in the infected brain in mice, which may explain exacerbated pathogenesis in comparison to those of the Asian lineage. Interestingly, viral RNA levels in different organs did not correlate with the pathogenicity of the different strains. Taken together, we have established a new murine model that supports ZIKV infection and demonstrate its utility in highlighting intrinsic differences in the inflammatory response induced by different ZIKV strains leading to severity of disease. This study paves the way for the future interrogation of strain-specific changes in the ZIKV genome and their contribution to viral pathogenesis.
- Published
- 2017
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45. Rescue of the 1947 Zika Virus Prototype Strain with a Cytomegalovirus Promoter-Driven cDNA Clone.
- Author
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Schwarz MC, Sourisseau M, Espino MM, Gray ES, Chambers MT, Tortorella D, and Evans MJ
- Abstract
The recent Zika virus (ZIKV) outbreak has been linked to severe pathogenesis. Here, we report the construction of a plasmid carrying a cytomegalovirus (CMV) promoter-expressed prototype 1947 Uganda MR766 ZIKV cDNA that can initiate infection following direct plasmid DNA transfection of mammalian cells. Incorporation of a synthetic intron in the nonstructural protein 1 (NS1) region of the ZIKV polyprotein reduced viral cDNA-associated toxicity in bacteria. High levels of infectious virus were produced following transfection of the plasmid bearing the wild-type MR766 ZIKV genome, but not one with a disruption to the viral nonstructural protein 5 (NS5) polymerase active site. Multicycle growth curve and plaque assay experiments indicated that the MR766 virus resulting from plasmid transfection exhibited growth characteristics that were more similar to its parental isolate than previously published 2010 Cambodia and 2015 Brazil cDNA-rescued ZIKV. This ZIKV infectious clone will be useful for investigating the genetic determinants of ZIKV infection and pathogenesis and should be amenable to construction of diverse infectious clones expressing reporter proteins and representing a range of ZIKV isolates. IMPORTANCE The study of ZIKV, which has become increasingly important with the recent association of this virus with microcephaly and Guillain-Barré syndrome, would benefit from an efficient strategy to genetically manipulate the virus. This work describes a model system to produce infectious virus in cell culture. We created a plasmid carrying the prototype 1947 Uganda MR766 ZIKV genome that both was stable in bacteria and could produce high levels of infectious virus in mammalian cells through direct delivery of this DNA. Furthermore, growth properties of this rescued virus closely resembled those of the viral isolate from which it was derived. This model system will provide a simple and effective means to study how ZIKV genetics impact viral replication and pathogenesis.
- Published
- 2016
- Full Text
- View/download PDF
46. Zika Virus Targets Human STAT2 to Inhibit Type I Interferon Signaling.
- Author
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Grant A, Ponia SS, Tripathi S, Balasubramaniam V, Miorin L, Sourisseau M, Schwarz MC, Sánchez-Seco MP, Evans MJ, Best SM, and García-Sastre A
- Subjects
- Animals, Base Sequence, Calmodulin-Binding Proteins metabolism, Chlorocebus aethiops, Cytoskeletal Proteins metabolism, Disease Models, Animal, HEK293 Cells drug effects, Humans, Interferon Type I metabolism, Mice, Phylogeny, Signal Transduction, Ubiquitin-Protein Ligases metabolism, Vero Cells, Viral Nonstructural Proteins genetics, Zika Virus Infection virology, Interferon Type I antagonists & inhibitors, STAT2 Transcription Factor metabolism, Viral Nonstructural Proteins metabolism, Zika Virus metabolism, Zika Virus Infection metabolism
- Abstract
The ongoing epidemic of Zika virus (ZIKV) illustrates the importance of flaviviruses as emerging human pathogens. All vector-borne flaviviruses studied thus far have to overcome type I interferon (IFN) to replicate and cause disease in vertebrates. The mechanism(s) by which ZIKV antagonizes IFN signaling is unknown. Here, we report that the nonstructural protein NS5 of ZIKV and other flaviviruses examined could suppress IFN signaling, but through different mechanisms. ZIKV NS5 expression resulted in proteasomal degradation of the IFN-regulated transcriptional activator STAT2 from humans, but not mice, which may explain the requirement for IFN deficiency to observe ZIKV-induced disease in mice. The mechanism of ZIKV NS5 resembles dengue virus (DENV) NS5 and not its closer relative, Spondweni virus (SPOV). However, unlike DENV, ZIKV did not require the E3 ubiquitin ligase UBR4 to induce STAT2 degradation. Hence, flavivirus NS5 proteins exhibit a remarkable functional convergence in IFN antagonism, albeit by virus-specific mechanisms., (Copyright © 2016 Elsevier Inc. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
47. Forecasting the risk of harmful algal blooms.
- Author
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Davidson K, Anderson DM, Mateus M, Reguera B, Silke J, Sourisseau M, and Maguire J
- Subjects
- Atlantic Ocean, Europe, Environmental Monitoring, Forecasting, Harmful Algal Bloom, Risk
- Abstract
The "Applied Simulations and Integrated Modelling for the Understanding of Harmful Algal Blooms" (Asimuth) project sought to develop a harmful algal bloom (HAB) alert system for Atlantic Europe. This was approached by combining, at a national or regional level, regulatory monitoring phytoplankton and biotoxin data with satellite remote sensing and other information on current marine conditions, coupled with regional scale models that included a representation of HAB transport. Synthesis of these products was achieved by expert interpretation within HAB risk alert bulletins that were prepared on a regular basis (typically weekly) for use by the aquaculture industry. In this preface to the Asimuth Special Issue we outline the main HAB species of concern in the region and the strengths and limitations of different methodologies to provide early warning of their blooms., (Copyright © 2015 Elsevier B.V. All rights reserved.)
- Published
- 2016
- Full Text
- View/download PDF
48. Viral Determinants of miR-122-Independent Hepatitis C Virus Replication.
- Author
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Hopcraft SE, Azarm KD, Israelow B, Lévêque N, Schwarz MC, Hsu TH, Chambers MT, Sourisseau M, Semler BL, and Evans MJ
- Abstract
Hepatitis C virus (HCV) replication requires binding of the liver-specific microRNA (miRNA) miR-122 to two sites in the HCV 5' untranslated region (UTR). Although we and others have shown that viral genetics impact the amount of active miR-122 required for replication, it is unclear if HCV can replicate in the complete absence of this miRNA. To probe the absolute requirements for miR-122 and the genetic basis for those requirements, we used clustered regularly interspaced short palindromic repeat (CRISPR) technology to knock out miR-122 in Huh-7.5 cells and reconstituted these knockout (KO) cells with either wild-type miR-122 or a mutated version of this miRNA. We then characterized the replication of the wild-type virus, as well as a mutated HCV bearing 5' UTR substitutions to restore binding to the mutated miR-122, in miR-122 KO Huh-7.5 cells expressing no, wild-type, or mutated miR-122. We found that while replication was most efficient when wild-type or mutated HCV was provided with the matched miR-122, inefficient replication could be observed in cells expressing the mismatched miR-122 or no miR-122. We then selected viruses capable of replicating in cells expressing noncognate miR-122 RNAs. Unexpectedly, these viruses contained multiple mutations throughout their first 42 nucleotides that would not be predicted to enhance binding of the provided miR-122. These mutations increased HCV RNA replication in cells expressing either the mismatched miR-122 or no miR-122. These data provide new evidence that HCV replication can occur independently of miR-122 and provide unexpected insights into how HCV genetics influence miR-122 requirements. IMPORTANCE Hepatitis C virus (HCV) is the leading cause of liver cancer in the Western Hemisphere. HCV infection requires miR-122, which is expressed only in liver cells, and thus is one reason that replication of this virus occurs efficiently only in cells of hepatic origin. To understand how HCV genetics impact miR-122 usage, we knocked out miR-122 using clustered regularly interspaced short palindromic repeat (CRISPR) technology and adapted virus to replicate in the presence of noncognate miR-122 RNAs. In doing so, we identified viral mutations that allow replication in the complete absence of miR-122. This work provides new insights into how HCV genetics influence miR-122 requirements and proves that replication can occur without this miRNA, which has broad implications for how HCV tropism is maintained.
- Published
- 2015
- Full Text
- View/download PDF
49. Significance of plankton community structure and nutrient availability for the control of dinoflagellate blooms by parasites: a modeling approach.
- Author
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Alves-de-Souza C, Pecqueur D, Le Floc'h E, Mas S, Roques C, Mostajir B, Vidussi F, Velo-Suárez L, Sourisseau M, Fouilland E, and Guillou L
- Subjects
- Animals, Computer Simulation, Eutrophication, Numerical Analysis, Computer-Assisted, Dinoflagellida parasitology, Dinoflagellida physiology, Food, Models, Biological, Parasites physiology, Plankton physiology
- Abstract
Dinoflagellate blooms are frequently observed under temporary eutrophication of coastal waters after heavy rains. Growth of these opportunistic microalgae is believed to be promoted by sudden input of nutrients and the absence or inefficiency of their natural enemies, such as grazers and parasites. Here, numerical simulations indicate that increasing nutrient availability not only promotes the formation of dinoflagellate blooms but can also stimulate their control by protozoan parasites. Moreover, high abundance of phytoplankton other than dinoflagellate hosts might have a significant dilution effect on the control of dinoflagellate blooms by parasites, either by resource competition with dinoflagellates (thus limiting the number of hosts available for infection) or by affecting numerical-functional responses of grazers that consume free-living parasite stages. These outcomes indicate that although both dinoflagellates and their protozoan parasites are directly affected by nutrient availability, the efficacy of the parasitic control of dinoflagellate blooms under temporary eutrophication depends strongly on the structure of the plankton community as a whole.
- Published
- 2015
- Full Text
- View/download PDF
50. Hepatitis C virus genetics affects miR-122 requirements and response to miR-122 inhibitors.
- Author
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Israelow B, Mullokandov G, Agudo J, Sourisseau M, Bashir A, Maldonado AY, Dar AC, Brown BD, and Evans MJ
- Subjects
- Base Sequence, Hepacivirus physiology, Hepatitis C genetics, Hepatitis C virology, Humans, Liver metabolism, Liver virology, MicroRNAs genetics, Molecular Sequence Data, Virus Replication, Hepacivirus genetics, Hepatitis C metabolism, MicroRNAs metabolism, Point Mutation
- Abstract
Hepatitis C virus (HCV) replication is dependent on a liver-specific microRNA (miRNA), miR-122. A recent clinical trial reported that transient inhibition of miR-122 reduced viral titres in HCV-infected patients. Here we set out to better understand how miR-122 inhibition influences HCV replication over time. Unexpectedly, we observed the emergence of an HCV variant that is resistant to miR-122 knockdown. Next-generation sequencing revealed that this was due to a single nucleotide change at position 28 (G28A) of the HCV genome, which falls between the two miR-122 seed-binding sites. Naturally occurring HCV isolates encoding G28A are similarly resistant to miR-122 inhibition, indicating that subtle differences in viral sequence, even outside the seed-binding site, greatly influence HCV's miR-122 concentration requirement. In addition, we found that HCV itself reduces miR-122's activity in the cell, possibly through binding and sequestering miR-122. Our study provides insight into the interaction between miR-122 and HCV, including viral adaptation to reduced miR-122 bioavailability, and has implications for the development of anti-miR-122-based HCV drugs.
- Published
- 2014
- Full Text
- View/download PDF
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