References of "Larosa, Véronique"
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See detailMitochondria affects photosynthetic electron transport and photo-sensitivity in a green alga
Larosa, Véronique ULiege; Meneghesso, Andrea; La Rocca, Nicoletta et al

in Plant Physiology (2017)

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See detailRegulation of mitochondrial respiration by modulating calcium fluxes in the green algae Chlamydomonas reinhardtii
Fattore, Nicolo; Remacle, Claire ULiege; Morosinotto, Tomas et al

Poster (2017, September 04)

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See detailA mitochondrial mutation increases high light resistance in Chlamydomonas reinhardtii.
Larosa, Véronique ULiege; Meneghesso, Andrea; La Rocca, Nicoletta et al

Poster (2017, September)

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See detailIn vivo chlorophyll fluorescence screening allows the isolation of a Chlamydomonas mutant defective for NDUFAF3, an assembly factor involved in mitochondrial complex I assembly
Massoz, Simon; Hanikenne, Marc ULiege; Bailleul, Benjamin et al

in Plant Journal (The) (2017), 17(8), 2045-2054

The qualitative screening method to select complex I mutants in the microalga Chlamydomonas, based on reduced growth under heterotrophic condition, is not suited for high throughput screening. In order to ... [more ▼]

The qualitative screening method to select complex I mutants in the microalga Chlamydomonas, based on reduced growth under heterotrophic condition, is not suited for high throughput screening. In order to develop a fast screening method based on measurements of chlorophyll fluorescence, we first demonstrated that complex I mutants displayed decreased photosystem II efficiency in the genetic background of a photosynthetic mutation leading to reduced formation of the electrochemical proton gradient in the chloroplast (pgrl1 mutation). In contrast, single mutants (complex I and pgrl1 mutants) could not be distinguished from wild type by their photosystem II efficiency in the tested conditions. We next performed an insertional mutagenesis on the pgrl1 mutant. Out of ~3000 hygromycin-resistant insertional transformants, 46 had decreased photosystem II efficiency and three were complex I mutants. One of the mutants was tagged and whole genome sequencing identified the resistance cassette in NDUFAF3, a homolog of the human NDUFAF3 gene, encoding for an assembly factor involved in complex I assembly. Complemented strains showed restored complex I activity and assembly. Overall, we described here a screening method which is fast and particularly suited for identification of Chlamydomonas complex I mutants. [less ▲]

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See detailPhysiological characterization of a plant mitochondrial Calcium uniporter in Vitro and in Vivo
Teardo, E.; Carraretto, L.; Wagner, S. et al

in Plant Physiology (2017), 173(2), 1355-1370

Over the recent years, several proteins that make up the mitochondrial calcium uniporter complex (MCUC) mediating Ca2+ uptake into the mitochondrial matrix have been identified in mammals, including the ... [more ▼]

Over the recent years, several proteins that make up the mitochondrial calcium uniporter complex (MCUC) mediating Ca2+ uptake into the mitochondrial matrix have been identified in mammals, including the channel-forming protein MCU. Although six MCU gene homologs are conserved in the model plant Arabidopsis (Arabidopsis thaliana) in which mitochondria can accumulate Ca2+, a functional characterization of plant MCU homologs has been lacking. Using electrophysiology, we show that one isoform, AtMCU1, gives rise to a Ca2+-permeable channel activity that can be observed even in the absence of accessory proteins implicated in the formation of the active mammalian channel. Furthermore, we provide direct evidence that AtMCU1 activity is sensitive to the mitochondrial calcium uniporter inhibitors Ruthenium Red and Gd3+, as well as to the Arabidopsis protein MICU, a regulatory MCUC component. AtMCU1 is prevalently expressed in roots, localizes to mitochondria, and its absence causes mild changes in Ca2+ dynamics as assessed by in vivo measurements in Arabidopsis root tips. Plants either lacking or overexpressing AtMCU1 display root mitochondria with altered ultrastructure and show shorter primary roots under restrictive growth conditions. In summary, our work adds evolutionary depth to the investigation of mitochondrial Ca2+ transport, indicates that AtMCU1, together with MICU as a regulator, represents a functional configuration of the plant mitochondrial Ca2+ uptake complex with differences to the mammalian MCUC, and identifies a new player of the intracellular Ca2+ regulation network in plants. © 2017 American Society of Plant Biologists. All rights reserved. [less ▲]

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See detailMerged heme and non-heme manganese cofactors for a dual antioxidant surveillance in photosynthetic organisms
Squarcina, A.; Sorarù, A.; Rigodanza, F. et al

in ACS Catalysis (2017), 7(3), 1971-1976

The coupling of a polycationic Mn(III)-porphyrin, with a dinuclear Mn2(II,II)L2 core (HL = 2-{[[di(2-pyridyl)methyl](methyl)amino]-methyl}phenol), results in a dual Superoxide Dismutase (SOD) and Catalase ... [more ▼]

The coupling of a polycationic Mn(III)-porphyrin, with a dinuclear Mn2(II,II)L2 core (HL = 2-{[[di(2-pyridyl)methyl](methyl)amino]-methyl}phenol), results in a dual Superoxide Dismutase (SOD) and Catalase (CAT) functional analogue, Mn2L2Pn+, enabling a detoxification cascade of the superoxide anion and hydrogen peroxide into benign H2O and O2. The SOD/CAT artificial manifolds, joined in one asset, exhibit a peak catalytic performance under physiological conditions, with log kcat(O2 •-) ≥ 7 and kcat(H2O2)/KM = 1890. The dual-enzyme (dizyme) concept allows for a builtin self-protection against the irreversible bleaching of the porphyrin unit (>75% protection), readily induced by H2O2 (200 μM, 20 equiv, in buffer solution, pH 7.8). We show herein that incubation of the photosynthetic green algae, Chlamydomonas reinhardtii, with the synthetic dizyme (as low as 0.1 μM), prevents H2O2 accumulation under high-light illumination conditions, thus providing antioxidant surveillance and photoprotection. (Chemical Equation Presented). © 2017 American Chemical Society. [less ▲]

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See detailA mitochondrial mutation increases high light resistance in Chlamydomonas reinhardtii.
Larosa, Véronique ULiege; Meneghesso, Andrea; Szabo, Ildiko et al

Conference (2016, August 10)

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See detailA mitochondrial mutation increases high light resistance in Chlamydomonas reinhardtii.
Larosa, Véronique ULiege; Meneghesso, Andrea; Remacle, Claire ULiege et al

Poster (2016, January 15)

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See detailA mitochondrial mutation increases high light resistance in Chlamydomonas reinhardtii.
Larosa, Véronique ULiege; Meneghesso, Andrea; Remacle, Claire ULiege et al

Poster (2015, September 15)

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See detailIsolation of Chlamydomonas reinhardtii mutants with altered mitochondrial respiration by chlorophyll fluorescence measurement.
Massoz, Simon; Larosa, Véronique ULiege; Horrion, Bastien et al

in Journal of biotechnology (2015)

The unicellular green alga Chlamydomonas reinhardtii is a model organism for studying energetic metabolism. Most mitochondrial respiratory-deficient mutants characterized to date have been isolated on the ... [more ▼]

The unicellular green alga Chlamydomonas reinhardtii is a model organism for studying energetic metabolism. Most mitochondrial respiratory-deficient mutants characterized to date have been isolated on the basis of their reduced ability to grow in heterotrophic conditions. Mitochondrial deficiencies are usually partly compensated by adjustment of photosynthetic activity and more particularly by transition to state 2. In this work, we explored the opportunity to select mutants impaired in respiration and/or altered in dark metabolism by measuring maximum photosynthetic efficiency by chlorophyll fluorescence analyses (FV/FM). Out of about 2900 hygromycin-resistant insertional mutants generated from wild type or from a mutant strain deficient in state transitions (stt7 strain), 22 were found to grow slowly in heterotrophic conditions and 8 of them also showed a lower FV/FM value. Several disrupted coding sequences were identified, including genes coding for three different subunits of respiratory-chain complex I (NUO9, NUOA9, NUOP4) or for isocitrate lyase (ICL1). Overall, the comparison of respiratory mutants obtained in wild-type or stt7 genetic backgrounds indicated that the FV/FM value can be used to isolate mutants severely impaired in dark metabolism. [less ▲]

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See detailLack of isocitrate lyase in Chlamydomonas leads to changes in carbon metabolism and in the response to oxidative stress under mixotrophic growth.
Plancke, Charlotte; Vigeolas, Hélène ULiege; Hohner, Ricarda et al

in The Plant journal : for cell and molecular biology (2014), 77(3), 404-417

Isocitrate lyase is a key enzyme of the glyoxylate cycle. This cycle plays an essential role in cell growth on acetate, and is important for gluconeogenesis as it bypasses the two oxidative steps of the ... [more ▼]

Isocitrate lyase is a key enzyme of the glyoxylate cycle. This cycle plays an essential role in cell growth on acetate, and is important for gluconeogenesis as it bypasses the two oxidative steps of the tricarboxylic acid (TCA) cycle in which CO2 is evolved. In this paper, a null icl mutant of the green microalga Chlamydomonas reinhardtii is described. Our data show that isocitrate lyase is required for growth in darkness on acetate (heterotrophic conditions), as well as for efficient growth in the light when acetate is supplied (mixotrophic conditions). Under these latter conditions, reduced acetate assimilation and concomitant reduced respiration occur, and biomass composition analysis reveals an increase in total fatty acid content, including neutral lipids and free fatty acids. Quantitative proteomic analysis by 14 N/15 N labelling was performed, and more than 1600 proteins were identified. These analyses reveal a strong decrease in the amounts of enzymes of the glyoxylate cycle and gluconeogenesis in parallel with a shift of the TCA cycle towards amino acid synthesis, accompanied by an increase in free amino acids. The decrease of the glyoxylate cycle and gluconeogenesis, as well as the decrease in enzymes involved in beta-oxidation of fatty acids in the icl mutant are probably major factors that contribute to remodelling of lipids in the icl mutant. These modifications are probably responsible for the elevation of the response to oxidative stress, with significantly augmented levels and activities of superoxide dismutase and ascorbate peroxidase, and increased resistance to paraquat. [less ▲]

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See detailInactivation of genes coding for mitochondrial Nd7 and Nd9 complex I subunits in Chlamydomonas reinhardtii. Impact of complex I loss on respiration and energetic metabolism.
Massoz, Simon; Larosa, Véronique ULiege; Plancke, Charlotte et al

in Mitochondrion (2013)

In Chlamydomonas, unlike in flowering plants, genes coding for Nd7 (NAD7/49kDa) and Nd9 (NAD9/30kDa) core subunits of mitochondrial respiratory-chain complex I are nucleus-encoded. Both genes possess all ... [more ▼]

In Chlamydomonas, unlike in flowering plants, genes coding for Nd7 (NAD7/49kDa) and Nd9 (NAD9/30kDa) core subunits of mitochondrial respiratory-chain complex I are nucleus-encoded. Both genes possess all the features that facilitate their expression and proper import of the polypeptides in mitochondria. By inactivating their expression by RNA interference or insertional mutagenesis, we show that both subunits are required for complex I assembly and activity. Inactivation of complex I impairs the cell growth rate, reduces the respiratory rate, leads to lower intracellular ROS production and lower expression of ROS scavenging enzymes, and is associated to a diminished capacity to concentrate CO2 without compromising photosynthetic capacity. [less ▲]

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See detailTransformation of the mitochondrial genome.
Larosa, Véronique ULiege; Remacle, Claire ULiege

in International Journal of Developmental Biology (2013), 57

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See detailRespiratory-deficient mutants of the unicellular green alga Chlamydomonas: A review.
Salinas, Thalia; Larosa, Véronique ULiege; Cardol, Pierre ULiege et al

in Biochimie (2013)

Genetic manipulation of the unicellular green alga Chlamydomonas reinhardtii is straightforward. Nuclear genes can be interrupted by insertional mutagenesis or targeted by RNA interference whereas random ... [more ▼]

Genetic manipulation of the unicellular green alga Chlamydomonas reinhardtii is straightforward. Nuclear genes can be interrupted by insertional mutagenesis or targeted by RNA interference whereas random or site-directed mutagenesis allows the introduction of mutations in the mitochondrial genome. This, combined with a screen that easily allows discriminating respiratory-deficient mutants, makes Chlamydomonas a model system of choice to study mitochondria biology in photosynthetic organisms. Since the first description of Chlamydomonas respiratory-deficient mutants in 1977 by random mutagenesis, many other mutants affected in mitochondrial components have been characterized. These respiratory-deficient mutants increased our knowledge on function and assembly of the respiratory enzyme complexes. More recently some of these mutants allowed the study of mitochondrial gene expression processes poorly understood in Chlamydomonas. In this review, we update the data concerning the respiratory components with a special focus on the assembly factors identified on other organisms. In addition, we make an inventory of different mitochondrial respiratory mutants that are inactivated either on mitochondrial or nuclear genes. [less ▲]

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See detailReconstruction of a human mitochondrial complex I mutation in the unicellular green alga Chlamydomonas.
Larosa, Véronique ULiege; Coosemans, Nadine ULiege; Motte, Patrick ULiege et al

in Plant Journal (The) (2012), 70

Defects in complex I (NADH:ubiquinone oxidoreductase) are the most frequent cause of human respiratory disorders. The pathogenicity of a given human mitochondrial mutation can be difficult to demonstrate ... [more ▼]

Defects in complex I (NADH:ubiquinone oxidoreductase) are the most frequent cause of human respiratory disorders. The pathogenicity of a given human mitochondrial mutation can be difficult to demonstrate because the mitochondrial genome harbors large numbers of polymorphic base changes that have no pathogenic significance. In addition, mitochondrial mutations are usually found in the heteroplasmic state, which could hide the biochemical effect of the mutation. We propose that the unicellular green alga Chlamydomonas could be used to study such mutations because (1) respiratory-deficient mutants are viable and mitochondrial mutations are found in the homoplasmic state, (2) transformation of the mitochondrial genome is feasible, (3) Chlamydomonas complex I is close to that of humans. To illustrate that, we have introduced a Leu157Pro substitution in the Chlamydomonas ND4 subunit of complex I of two different recipient strains by biolistic transformation, demonstrating that site-directed mutagenesis of the Chlamydomonas mitochondrial genome is possible. This substitution did not lead to any respiratory enzyme defect when it is present in the heteroplasmic state in a patient presenting chronic progressive external ophthalmoplegia. When present in the homoplasmic state in the alga, the mutation does not prevent the assembly of the 950 kDa whole complex I which conserves nearly all the NADH dehydrogenase activity of the peripheral arm. However, the NADH:duroquinone oxidoreductase activity is strongly reduced, suggesting that the substitution could affect ubiquinone fixation to the membrane domain. The in vitro defects are correlated in vivo with a decrease in dark respiration and growth rate. [less ▲]

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See detailMitochondrial transformation and in vitro DNA delivery
Remacle, Claire ULiege; Hamel, Patrice; Larosa, Véronique ULiege et al

in Bock, R; Knoop, V (Eds.) Genomics of Chloroplasts and Mitochondria (2012)

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