12 results on '"Isabelle Baró"'
Search Results
2. Predicting hERG repolarization power at 37°C from recordings at room temperature
- Author
-
Barbara B. R. Oliveira‐Mendes, Malak Alameh, Jérôme Montnach, Béatrice Ollivier, Solène Gibaud, Sylvain Feliciangeli, Florian Lesage, Flavien Charpentier, Gildas Loussouarn, Michel De Waard, and Isabelle Baró more...
- Subjects
Medicine (General) ,R5-920 - Published
- 2023
- Full Text
- View/download PDF
Catalog
3. SARS-CoV-2 E and 3a Proteins Are Inducers of Pannexin Currents
- Author
-
Barbara B. R. Oliveira-Mendes, Malak Alameh, Béatrice Ollivier, Jérôme Montnach, Nicolas Bidère, Frédérique Souazé, Nicolas Escriou, Flavien Charpentier, Isabelle Baró, Michel De Waard, and Gildas Loussouarn more...
- Subjects
COVID-19 ,SARS-CoV-2 ,viroporins ,E protein ,3a protein ,pannexin currents ,Cytology ,QH573-671 - Abstract
Controversial reports have suggested that SARS-CoV E and 3a proteins are plasma membrane viroporins. Here, we aimed at better characterizing the cellular responses induced by these proteins. First, we show that expression of SARS-CoV-2 E or 3a protein in CHO cells gives rise to cells with newly acquired round shapes that detach from the Petri dish. This suggests that cell death is induced upon expression of E or 3a protein. We confirmed this by using flow cytometry. In adhering cells expressing E or 3a protein, the whole-cell currents were not different from those of the control, suggesting that E and 3a proteins are not plasma membrane viroporins. In contrast, recording the currents on detached cells uncovered outwardly rectifying currents much larger than those observed in the control. We illustrate for the first time that carbenoxolone and probenecid block these outwardly rectifying currents; thus, these currents are most probably conducted by pannexin channels that are activated by cell morphology changes and also potentially by cell death. The truncation of C-terminal PDZ binding motifs reduces the proportion of dying cells but does not prevent these outwardly rectifying currents. This suggests distinct pathways for the induction of these cellular events by the two proteins. We conclude that SARS-CoV-2 E and 3a proteins are not viroporins expressed at the plasma membrane. more...
- Published
- 2023
- Full Text
- View/download PDF
4. Computer modeling of whole-cell voltage-clamp analyses to delineate guidelines for good practice of manual and automated patch-clamp
- Author
-
Jérôme Montnach, Maxime Lorenzini, Adrien Lesage, Isabelle Simon, Sébastien Nicolas, Eléonore Moreau, Céline Marionneau, Isabelle Baró, Michel De Waard, and Gildas Loussouarn
- Subjects
Medicine ,Science - Abstract
Abstract The patch-clamp technique and more recently the high throughput patch-clamp technique have contributed to major advances in the characterization of ion channels. However, the whole-cell voltage-clamp technique presents certain limits that need to be considered for robust data generation. One major caveat is that increasing current amplitude profoundly impacts the accuracy of the biophysical analyses of macroscopic ion currents under study. Using mathematical kinetic models of a cardiac voltage-gated sodium channel and a cardiac voltage-gated potassium channel, we demonstrated how large current amplitude and series resistance artefacts induce an undetected alteration in the actual membrane potential and affect the characterization of voltage-dependent activation and inactivation processes. We also computed how dose–response curves are hindered by high current amplitudes. This is of high interest since stable cell lines frequently demonstrating high current amplitudes are used for safety pharmacology using the high throughput patch-clamp technique. It is therefore critical to set experimental limits for current amplitude recordings to prevent inaccuracy in the characterization of channel properties or drug activity, such limits being different from one channel type to another. Based on the predictions generated by the kinetic models, we draw simple guidelines for good practice of whole-cell voltage-clamp recordings. more...
- Published
- 2021
- Full Text
- View/download PDF
5. A standardised hERG phenotyping pipeline to evaluate KCNH2 genetic variant pathogenicity
- Author
-
Barbara Oliveira‐Mendes, Sylvain Feliciangeli, Mélissa Ménard, Frank Chatelain, Malak Alameh, Jérôme Montnach, Sébastien Nicolas, Béatrice Ollivier, Julien Barc, Isabelle Baró, Jean‐Jacques Schott, Vincent Probst, Florence Kyndt, Isabelle Denjoy, Florian Lesage, Gildas Loussouarn, and Michel De Waard more...
- Subjects
arrhythmias ,diagnostic testing ,genetic variant ,hERG ion channel ,pathogenicity ,QT syndrome ,Medicine (General) ,R5-920 - Abstract
Abstract Background and aims Mutations in KCNH2 cause long or short QT syndromes (LQTS or SQTS) predisposing to life‐threatening arrhythmias. Over 1000 hERG variants have been described by clinicians, but most remain to be characterised. The objective is to standardise and accelerate the phenotyping process to contribute to clinician diagnosis and patient counselling. In silico evaluation was also included to characterise the structural impact of the variants. Methods We selected 11 variants from known LQTS patients and two variants for which diagnosis was problematic. Using the Gibson assembly strategy, we efficiently introduced mutations in hERG cDNA despite GC‐rich sequences. A pH‐sensitive fluorescent tag was fused to hERG for efficient evaluation of channel trafficking. An optimised 35‐s patch‐clamp protocol was developed to evaluate hERG channel activity in transfected cells. R software was used to speed up analyses. Results In the present work, we observed a good correlation between cell surface expression, assessed by the pH‐sensitive tag, and current densities. Also, we showed that the new biophysical protocol allows a significant gain of time in recording ion channel properties and provides extensive information on WT and variant channel biophysical parameters, that can all be recapitulated in a single parameter defined herein as the repolarisation power. The impacts of the variants on channel structure were also reported where structural information was available. These three readouts (trafficking, repolarisation power and structural impact) define three pathogenicity indexes that may help clinical diagnosis. Conclusions Fast‐track characterisation of KCNH2 genetic variants shows its relevance to discriminate mutants that affect hERG channel activity from variants with undetectable effects. It also helped the diagnosis of two new variants. This information is meant to fill a patient database, as a basis for personalised medicine. The next steps will be to further accelerate the process using an automated patch‐clamp system. more...
- Published
- 2021
- Full Text
- View/download PDF
6. A consistent arrhythmogenic trait in Brugada syndrome cellular phenotype
- Author
-
Zeina R. Al Sayed, Mariam Jouni, Jean‐Baptiste Gourraud, Nadjet Belbachir, Julien Barc, Aurore Girardeau, Virginie Forest, Aude Derevier, Anne Gaignerie, Caroline Chariau, Bastien Cimarosti, Robin Canac, Pierre Olchesqui, Eric Charpentier, Jean‐Jacques Schott, Richard Redon, Isabelle Baró, Vincent Probst, Flavien Charpentier, Gildas Loussouarn, Kazem Zibara, Guillaume Lamirault, Patricia Lemarchand, and Nathalie Gaborit more...
- Subjects
Medicine (General) ,R5-920 - Published
- 2021
- Full Text
- View/download PDF
7. Dysfunction of the Voltage‐Gated K+ Channel β2 Subunit in a Familial Case of Brugada Syndrome
- Author
-
Vincent Portero, Solena Le Scouarnec, Zeineb Es‐Salah‐Lamoureux, Sophie Burel, Jean‐Baptiste Gourraud, Stéphanie Bonnaud, Pierre Lindenbaum, Floriane Simonet, Jade Violleau, Estelle Baron, Eléonore Moreau, Carol Scott, Stéphanie Chatel, Gildas Loussouarn, Thomas O'Hara, Philippe Mabo, Christian Dina, Hervé Le Marec, Jean‐Jacques Schott, Vincent Probst, Isabelle Baró, Céline Marionneau, Flavien Charpentier, and Richard Redon more...
- Subjects
Brugada syndrome ,cardiac arrhythmia ,clinical electrophysiology ,genetics ,KCNAB2/Kvβ2 ,potassium ion channels ,Diseases of the circulatory (Cardiovascular) system ,RC666-701 - Abstract
BackgroundThe Brugada syndrome is an inherited cardiac arrhythmia associated with high risk of sudden death. Although 20% of patients with Brugada syndrome carry mutations in SCN5A, the molecular mechanisms underlying this condition are still largely unknown. Methods and ResultsWe combined whole‐exome sequencing and linkage analysis to identify the genetic variant likely causing Brugada syndrome in a pedigree for which SCN5A mutations had been excluded. This approach identified 6 genetic variants cosegregating with the Brugada electrocardiographic pattern within the pedigree. In silico gene prioritization pointed to 1 variant residing in KCNAB2, which encodes the voltage‐gated K+ channel β2‐subunit (Kvβ2‐R12Q). Kvβ2 is widely expressed in the human heart and has been shown to interact with the fast transient outward K+ channel subunit Kv4.3, increasing its current density. By targeted sequencing of the KCNAB2 gene in 167 unrelated patients with Brugada syndrome, we found 2 additional rare missense variants (L13F and V114I). We then investigated the physiological effects of the 3 KCNAB2 variants by using cellular electrophysiology and biochemistry. Patch‐clamp experiments performed in COS‐7 cells expressing both Kv4.3 and Kvβ2 revealed a significant increase in the current density in presence of the R12Q and L13F Kvβ2 mutants. Although biotinylation assays showed no differences in the expression of Kv4.3, the total and submembrane expression of Kvβ2‐R12Q were significantly increased in comparison with wild‐type Kvβ2. ConclusionsAltogether, our results indicate that Kvβ2 dysfunction can contribute to the Brugada electrocardiographic pattern. more...
- Published
- 2016
- Full Text
- View/download PDF
8. A long QT mutation substitutes cholesterol for phosphatidylinositol-4,5-bisphosphate in KCNQ1 channel regulation.
- Author
-
Fabien C Coyan, Fayal Abderemane-Ali, Mohamed Yassine Amarouch, Julien Piron, Jérôme Mordel, Céline S Nicolas, Marja Steenman, Jean Mérot, Céline Marionneau, Annick Thomas, Robert Brasseur, Isabelle Baró, and Gildas Loussouarn more...
- Subjects
Medicine ,Science - Abstract
INTRODUCTION:Phosphatidylinositol-4,5-bisphosphate (PIP2) is a cofactor necessary for the activity of KCNQ1 channels. Some Long QT mutations of KCNQ1, including R243H, R539W and R555C have been shown to decrease KCNQ1 interaction with PIP2. A previous study suggested that R539W is paradoxically less sensitive to intracellular magnesium inhibition than the WT channel, despite a decreased interaction with PIP2. In the present study, we confirm this peculiar behavior of R539W and suggest a molecular mechanism underlying it. METHODS AND RESULTS:COS-7 cells were transfected with WT or mutated KCNE1-KCNQ1 channel, and patch-clamp recordings were performed in giant-patch, permeabilized-patch or ruptured-patch configuration. Similar to other channels with a decreased PIP2 affinity, we observed that the R243H and R555C mutations lead to an accelerated current rundown when membrane PIP2 levels are decreasing. As opposed to R243H and R555C mutants, R539W is not more but rather less sensitive to PIP2 decrease than the WT channel. A molecular model of a fragment of the KCNQ1 C-terminus and the membrane bilayer suggested that a potential novel interaction of R539W with cholesterol stabilizes the channel opening and hence prevents rundown upon PIP2 depletion. We then carried out the same rundown experiments under cholesterol depletion and observed an accelerated R539W rundown that is consistent with this model. CONCLUSIONS:We show for the first time that a mutation may shift the channel interaction with PIP2 to a preference for cholesterol. This de novo interaction wanes the sensitivity to PIP2 variations, showing that a mutated channel with a decreased affinity to PIP2 could paradoxically present a slowed current rundown compared to the WT channel. This suggests that caution is required when using measurements of current rundown as an indicator to compare WT and mutant channel PIP2 sensitivity. more...
- Published
- 2014
- Full Text
- View/download PDF
9. Plaguicidas organoclorados: Respuesta de la macrofauna en ranchos de Xico, Veracruz
- Author
-
Carolina Valdespino, Lucrecia Arellano, Isabelle Barois, and Jaime Rendón von Osten
- Subjects
agroquímicos ,escarabajos ,estercoleros ,lombrices de tierra ,pastizales ,suelo ,Agriculture (General) ,S1-972 ,Animal culture ,SF1-1100 - Abstract
Objetivo. Determinar la presencia y concentraciones de plaguicidas organoclorados en el suelo de ranchos lecheros con producción rústica y tecnificada y analizar la presencia y abundancia de taxones de la macrofauna del suelo y su relación con las concentraciones de plaguicidas organoclorados del suelo. Materiales y métodos. Se caracterizaron zonas dentro de cada rancho, de acuerdo con las actividades que los propietarios llevan a cabo en cada uno y se efectuaron determinaciones de concentración de familias de plaguicidas organoclorados (∑DDT, ∑HCH, ∑Heptacloro, ∑Endosulfan, ∑Clordano, ∑Drines) y del número de individuos de los grupos taxonómicos de la macrofauna del suelo. Resultados. Se encontró una relación negativa, aunque no significativa, entre las concentraciones medidas y el número de organismos. Se reportaron las curvas de rango abundancia de los grupos evaluados para cada rancho, analizando la importancia relativa de los taxones encontrados. En algunos ranchos, los potreros tienen cantidades de organoclorados por debajo del límite de detección de los instrumentos utilizados en el laboratorio, asegurando una producción de leche libre de estos plaguicidas. Conclusiones. Los plaguicidas organoclorados pueden permanecer largo tiempo acumulados en el suelo, por lo que es necesario usar otras formas para la solución de problemas como las plagas y plantas no consumidas por el ganado, como el pastoreo racional o el establecimiento de sistemas silvopastoriles. more...
- Published
- 2024
- Full Text
- View/download PDF
10. Drivers of soil biophysical processes along an elevational gradient at Pico de Orizaba volcano, Mexico
- Author
-
Guillermo Angeles, Marycruz Álvarez-Jiménez, Fabien Anthelme, Isabelle Barois, José Luis Chaparro Carrillo, Nereyda Cruz-Maldonado, Thibaud Decaens, Martín de los Santos-Bailón, Stéphane Fourtier, Emmanuel García-Gutiérrez, David García-Segura, Rodrigo Gómez-Aguilar, Antonio Gómez-Anaya, Eduardo Hernández, Daniel Hernández-Cáceres, Leonor Jiménez, Beatriz E. Marín-Castro, Luis Merino-Martín, Marco A. Morales-Martínez, Edwin U. Monfil-León, René A. Palestina, Carlos Pimentel-Reyes, Ricardo Quiroz Reyes, Frédérique Reverchon, Hervé Rey, Catherine Roumet, Christina D. Siebe-Grabach, Katrin Sieron, Víctor Vázques Reyes, Monique Weemstra, and Alexia Stokes more...
- Subjects
Elevational gradient ,Bulk soil and rhizosphere microbial communities ,Carbon storage ,High mountain ecosystem ,Soil biodiversity ,Soil hydrophysical properties ,Agriculture (General) ,S1-972 - Abstract
Abstract Elevational gradients are characterized by major shifts in environmental conditions, reflected through changes in climatic and soil variables. These shifts strongly impact the composition, community structure and specific functional traits of vegetation. Vegetation, in turn, influences soil properties through litter input, root growth and the release of root exudates, thereby influencing soil microbial and faunal communities. Here, we report and briefly describe data of soil and underlying bedrock physical and chemical properties, climatic variables, plant community composition and species abundance, soil microbial diversity and macro and mesofaunal abundance and diversity. Data are provided for 6 elevations (3400–4600 m) ranging from pine forest to alpine prairie. We focused on soil biophysical properties beneath several keystone or community-structuring plant species with different growth forms: (1) tree (Pinus hartwegii Lindl.); shrub (Oxylobus arbutifolius (Kunth) A. Gray and Chionolaena lavandulifolia (Kunth ex Kunth) Benth. & Hook.f. ex B.D.Jacks.); and (3) herb (Lupinus montanus Kunth and Senecio roseus Sch.Bip.). These data are useful for understanding how shifts in abiotic conditions and vegetation communities along an elevational gradient affect soil ecosystem services such as water infiltration, soil aggregation and carbon (C) storage, and modify soil biodiversity. The collected data also provide useful information to understand how alpine vegetation, soil macro- and meso-fauna, and soil bacterial communities may shift under a climate change scenario. more...
- Published
- 2023
- Full Text
- View/download PDF
11. Shifts in soil and plant functional diversity along an altitudinal gradient in the French Alps
- Author
-
Alexia Stokes, Guillermo Angeles, Fabien Anthelme, Eduardo Aranda-Delgado, Isabelle Barois, Manon Bounous, Nereyda Cruz-Maldonado, Thibaud Decaëns, Stéphane Fourtier, Grégoire T. Freschet, Quentin Gabriac, Daniel Hernández-Cáceres, Leonor Jiménez, Jing Ma, Zhun Mao, Beatriz Eugenia Marín-Castro, Luis Merino-Martín, Awaz Mohamed, Christian Piedallu, Carlos Pimentel-Reyes, Hans Reijnen, Frédérique Reverchon, Hervé Rey, Lavinia Selli, Christina Desireé Siebe-Grabach, Katrin Sieron, Monique Weemstra, and Catherine Roumet more...
- Subjects
Aggregate stability ,Alpine ecosystems ,Carbon ,Community ,Elevation ,Environmental gradient ,Medicine ,Biology (General) ,QH301-705.5 ,Science (General) ,Q1-390 - Abstract
Abstract Objectives Altitude integrates changes in environmental conditions that determine shifts in vegetation, including temperature, precipitation, solar radiation and edaphogenetic processes. In turn, vegetation alters soil biophysical properties through litter input, root growth, microbial and macrofaunal interactions. The belowground traits of plant communities modify soil processes in different ways, but it is not known how root traits influence soil biota at the community level. We collected data to investigate how elevation affects belowground community traits and soil microbial and faunal communities. This dataset comprises data from a temperate climate in France and a twin study was performed in a tropical zone in Mexico. Data description The paper describes soil physical and chemical properties, climatic variables, plant community composition and species abundance, plant community traits, soil microbial functional diversity and macrofaunal abundance and diversity. Data are provided for six elevations (1400–2400 m) ranging from montane forest to alpine prairie. We focused on soil biophysical properties beneath three dominant plant species that structure local vegetation. These data are useful for understanding how shifts in vegetation communities affect belowground processes, such as water infiltration, soil aggregation and carbon storage. Data will also help researchers understand how plant communities adjust to a changing climate/environment. more...
- Published
- 2021
- Full Text
- View/download PDF
12. Earthworms Building Up Soil Microbiota, a Review
- Author
-
Regina M. Medina-Sauza, Marycruz Álvarez-Jiménez, Alix Delhal, Frédérique Reverchon, Manuel Blouin, José A. Guerrero-Analco, Carlos R. Cerdán, Roger Guevara, Luc Villain, and Isabelle Barois
- Subjects
soil nutrient hotspots ,interactions ,soil biotransformation ,signal molecules ,drilosphere ,microbiome ,Environmental sciences ,GE1-350 - Abstract
The positive effect of earthworms on soil processes and plant growth has been extensively documented. The capacity of earthworms to decompose organic matter has been attributed to the microbial communities that inhabit their digestive track or the structures they build, which in turn contribute to make up the drilosphere, a hotspot for microbial activity. However, how earthworms modify the structure of soil microbial communities and how these changes affect soil microbial processes is still unclear. Do earthworms reduce microbial abundance and activity because they feed on microorganisms or do they select and stimulate specific microbial groups? We hypothesise that “the effect of earthworms on nutrient cycling and plant growth is not only a direct effect but is mainly mediated indirectly, via modifications of the microbial community.” The objective of this review is to synthesize the existing literature concerning the influence of earthworms on the structure and function of soil microbial communities, as well as to understand how earthworm-induced changes in the soil microbiota would in turn impact soil processes, particularly those occurring in the rhizosphere and involved in plant growth and health. Recent reports have shown that specific bacterial groups consistently increase in soils where earthworms are present, regardless of the earthworm functional group. The extent of this increase seems to be dependent upon the type of substrate under study. Our synthesis also reveals that endogeic and anecic earthworms regularly induce an increase in soil nutrients, whilst this positive effect is not as evident in the presence of epigeic earthworms. The effect of earthworms on nutrient cycling has been further investigated with microbial functional genes, although existing reports largely focus on nitrogen cycling. Earthworms seem to enhance denitrification, most likely through the increase in organic compounds due to organic matter decomposition. By enhancing soil nutrient availability, earthworms indirectly promote plant growth, which has also been attributed to the induction of signal molecules. However, no experiment to date has been able to prove a direct causal relationship between specific signal molecules, earthworms and plant growth promotion. Finally, we propose a framework for earthworm-microbiota interactions and recommend further research. more...
- Published
- 2019
- Full Text
- View/download PDF
Discovery Service for Jio Institute Digital Library
For full access to our library's resources, please sign in.