References of "Remacle, Claire"
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See detailMitochondrial transformation and in vitro DNA delivery
Remacle, Claire ULg; Hamel, Patrice; Larosa, Véronique ULg et al

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

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See detailComplexes I in the green lineage.
Remacle, Claire ULg; Hamel, Patrice; Larosa, Véronique ULg et al

in Sazanov, Leonid (Ed.) A structural perspective on complex I. (2012)

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See detailGreen Algae Genomics: A Mitochondrial Perspective
Rodriguez-Salinas, E; Remacle, Claire ULg; Gonzalez-Halphen, Diego

in Maréchal-Drouard, Laurence (Ed.) Mitochondrial Genome Evolution (2012)

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See detailFinding the bottleneck: a research strategy for improved biomass production
Bassi, Roberto; Cardol, Pierre ULg; Choquet, Yves et al

in Posten, Clemens; Walter, Christian (Eds.) Microalgal Biotechnology: integration and economy (2012)

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See detailFunction of the chloroplastic NADP(H) dehydrogenase NDA2 for the H2 photoproduction in sulphur-deprived Chlamydomonas reinhardtii
Mignolet, Emmanuel ULg; Lecler, Renaud ULg; Ghysels, Bart ULg et al

in Journal of Biotechnology (2012), 162

The relative contributions of the PSII-dependent and Nda2-dependent pathways for H2 photoproduction were investigated in the green microalga Chlamydomonas reinhardtii after suphur-deprivation. For this ... [more ▼]

The relative contributions of the PSII-dependent and Nda2-dependent pathways for H2 photoproduction were investigated in the green microalga Chlamydomonas reinhardtii after suphur-deprivation. For this purpose, H2 gas production was compared for wild-type and Nda2-deficient cells with or without DCMU (a PSII-inhibitor) in the same experimental conditions. Nda2-deficiency caused a 30 % decrease of the maximal H2 photoevolution rate observed shortly after the establishment of anoxia, and an acceleration of the decline of H2 photoevolution rate with time. DCMU addition to Nda2-deficient cells completely inhibited H2 photoproduction, showing that the PSII-independent H2 photoproduction relies on the presence of Nda2, which feeds the photosynthetic electron transport chain with electrons derived from oxidative catabolism. Nda2-protein abundance increased as a result of sulphur deprivation and further during the H2 photoproduction process, resulting in high rates of non-photochemical plastoquinone reduction in control cells. Nda2-deficiency had no significant effect on photosynthetic and respiratory capacities in sulphur-deprived cells, but caused changes in the cell energetic status (ATP and NADPH/NADP+ ratio). The rapid decline of H2 photoevolution rate with time in Nda2-deficient cells revealed a more pronounced inhibition of H2 photoproduction by accumulated H2 in the absence of non-photochemical plastoquinone reduction. Nda2 is therefore important for linking H2 photoproduction with catabolism of storage carbon compounds, and seems also involved in regulating the redox poise of the photosynthetic electron transport chain during H2 photoproduction. [less ▲]

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See detailInsertional mutagenesis to select mutants for modified hydrogen photoproduction in Chlamydomonas reinhardtii
Godaux, Damien ULg; Emonds-alt, Barbara; Cardol, Pierre ULg et al

Poster (2011, September 18)

The unicellular green alga Chlamydomonas reinhardtii has evolved the ability to redirect electrons from the photosynthetic chain to drive hydrogen production via chloroplast oxygen-sensitive hydrogenases ... [more ▼]

The unicellular green alga Chlamydomonas reinhardtii has evolved the ability to redirect electrons from the photosynthetic chain to drive hydrogen production via chloroplast oxygen-sensitive hydrogenases. This process occurs under anaerobic conditions and provides a biological basis for solar-driven hydrogen production. Nevertheless, the yield is a major limitation for an economic viability and fundamental knowledge is still needed in order to have a better understanding of the process. In 2000, Melis and co-worker defined a protocol allowing a sustainable hydrogen production in sulfur deprivation condition. By adjustment of an existent protocol called the Winkler test, we are trying to isolate mutants with an attenuated photosynthesis to respiration capacity ratio (P/R ratio). This kind of mutants could be able to reach anoxia needed for hydrogenases activity without the stressful impact of sulfur deprivation. An insertional mutagenesis of Chlamydomonas has been carried out with an hygromycin resistance cassette and about 2500 transformants have generated and screened by the adapted Winkler test. We have isolated several oxygen-consuming mutants and the most promising one is subject to functional, molecular and genetic characterization. [less ▲]

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See detailInsertional mutagenesis to select mutants for modified hydrogen photoproduction in Chlamydomonas reinhardtii
Godaux, Damien ULg; Emonds-Alt, Barbara ULg; Cardol, Pierre ULg et al

Poster (2011, May 17)

The unicellular green alga Chlamydomonas reinhardtii has evolved the ability to redirect electrons from the photosynthetic chain to drive hydrogen production via chloroplast oxygen-sensitive hydrogenases ... [more ▼]

The unicellular green alga Chlamydomonas reinhardtii has evolved the ability to redirect electrons from the photosynthetic chain to drive hydrogen production via chloroplast oxygen-sensitive hydrogenases. This process occurs under anaerobic conditions and provides a biological basis for solar-driven hydrogen production. Nevertheless, the yield is a major limitation for an economic viability and fundamental knowledge is still needed in order to have a better understanding of the process. In 2000, Melis and co-worker defined a protocol allowing a sustainable hydrogen production in sulfur deprivation condition. By adjustment of an existent protocol called the Winkler test, we are trying to isolate mutants with an attenuated photosynthesis to respiration capacity ratio (P/R ratio). This kind of mutants could be able to reach anoxia needed for hydrogenases activity without the stressful impact of sulfur deprivation. An insertional mutagenesis of Chlamydomonas has been carried out with an hygromycin resistance cassette and about 2500 transformants have generated and screened by the adapted Winkler test. We have isolated several oxygen-consuming mutants and the most promising one is subject to functional, molecular and genetic characterization. To discover new genes involved in hydrogenases activity, we are also planning to screen the same insertional library for mutants with attenuated levels of hydrogen photoproduction, using sensitive chemochromic sensor films which turn in blue in presence of hydrogen. We are currently making the chemochromic sensor WO3 films by dip-coating which is on the brink of being useable. [less ▲]

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See detailImport of tRNA in Chlamydomonas reinhardtii mitochondria
Remacle, Claire ULg

Conference (2011, May 16)

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See detailA Forward Genetic Screen Identifies Mutants Deficient for Mitochondrial Complex I Assembly in Chlamydomonas Reinhardtii.
Barbieri, M. R.; Larosa, Véronique ULg; Nouet, Cécile ULg et al

in Genetics (2011), 188

Mitochondrial Complex I is the largest multimeric enzyme of the respiratory chain. The lack of a model system with facile genetics has limited the molecular dissection of Complex I assembly. Using ... [more ▼]

Mitochondrial Complex I is the largest multimeric enzyme of the respiratory chain. The lack of a model system with facile genetics has limited the molecular dissection of Complex I assembly. Using Chlamydomonas reinhardtii as an experimental system to screen for Complex I defects, we isolated, via forward genetics, amc1 to 7 nuclear mutants (for assembly of mitochondrial complex I) displaying reduced or no Complex I activity. BN-PAGE and immunoblot analyses revealed that amc3 and amc4 accumulate reduced levels of the Complex I holoenzyme (950 kDa) while all other amc mutants fail to accumulate a mature complex. In amc1, 2, 5, 6, 7, the detection of a 700 kDa subcomplex retaining NADH dehydrogenase activity indicates an arrest in the assembly process. Genetic analyses established that amc5 and amc7 are alleles of the same locus while amc1 to 4 and amc6 define distinct complementation groups. The locus defined by the amc5 and amc7 alleles corresponds to the NUOB10 gene, encoding PDSW, a subunit of the membrane arm of Complex I. This is the first report of a forward genetic screen yielding the isolation of Complex I mutants. This work illustrates the potential of using Chlamydomonas as a genetically-tractable organism to decipher Complex I manufacture. [less ▲]

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See detailFunctional analysis of hydrogen photoproduction in respiratory-deficient mutants of Chlamydomonas reinhardtii
Lecler, Renaud ULg; Godaux, Damien ULg; Vigeolas, Hélène ULg et al

in International Journal of Hydrogen Energy (2011), 36

In this paper, mitochondrial mutants of Chlamydomonas reinhardtii defective for respiratory complex I (NADH:ubiquinone oxidoreductase), complex III (ubiquinol cytochrome c oxidoreductase) and both ... [more ▼]

In this paper, mitochondrial mutants of Chlamydomonas reinhardtii defective for respiratory complex I (NADH:ubiquinone oxidoreductase), complex III (ubiquinol cytochrome c oxidoreductase) and both complexes I and III were analyzed for H2 photoproduction. Several parameters were followed during the S-deficiency stage and the anaerobic stage leading to H2 photoproduction. At the early aerobic S-deficiency stage, starch and neutral lipids accumulated in all strains but their amount was significantly decreased in mutants compared to wild type. During the H2 photoproduction process, whereas starch content strongly decreased in all strains, neutral lipid amount remained nearly unchanged, suggesting that starch degraded by glycolysis is the preferential substrate for energy production during anaerobiosis. The mutants displayed a decrease in H2 photoproduction correlating to the number of active mitochondrial proton-pumping sites lost in the strains. Our results thus highlight the critical role of oxidative phosphorylation during the first (aerobic) stage of S-starvation when carbon resources are accumulated. [less ▲]

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See detailChlamydomonas can play a role in the study of a heteroplasmic human mitochondrial mutation
Larosa, Véronique ULg; Coosemans, Nadine ULg; Bonnefoy, Nathalie et al

Scientific conference (2011)

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See detailCharacterization of a knock-down mutant deficient for isocitrate lyase in Chlamydomonas reinhardtii
Remacle, Claire ULg

in Microorganisms for bio-fuel production from sunlight, ESF conference (2011)

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See detail3D-reconstruction and overall topology of the dimeric mitochondrial ATP synthase of the colorless alga Polytomella sp
González-Halphen, Diego; Vázquez-Acevedo, Myriam; Cano-Estrada, Araceli et al

in Biochimica et Biophysica Acta (BBA) - Bioenergetics (2010, July), 1797(Supplement 1), 32

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See detailAtypical subunit composition of the chlorophycean mitochondrial F1FO ATP synthase and role of Asa7 protein in stability and oligomycin resistance of the enzyme.
Lapaille, Marie; Escobar-Ramirez, Adelma; Degand, Hervé et al

in Molecular Biology and Evolution (2010), 27(7), 1630-1644

Background. In yeast, mammals, and land plants, mitochondrial F(1)F(O) ATP synthase (complex V) is a remarkable enzymatic machinery which comprises about 15 conserved subunits. Peculiar among eukaryotes ... [more ▼]

Background. In yeast, mammals, and land plants, mitochondrial F(1)F(O) ATP synthase (complex V) is a remarkable enzymatic machinery which comprises about 15 conserved subunits. Peculiar among eukaryotes, complex V from Chlamydomonadales algae (order of chlorophycean class) has an atypical subunit composition of its peripheral stator and dimerization module, with 9 subunits of unknown evolutionary origin (Asa subunits). In vitro, this enzyme exhibits an increased stability of its dimeric form, and in vivo, Chlamydomonas reinhardtii cells are insensitive to oligomycins, which are potent inhibitors of proton translocation through the F(O) moiety. Methodology/Principal Findings. In this work, we showed that the atypical features of the Chlamydomonadales complex V enzyme are shared by the other chlorophycean orders. By biochemical and in silico analyses, we detected several atypical Asa subunits in Scenedesmus obliquus (Sphaeropleales) and Chlorococcum ellipsoideum (Chlorococcales). In contrast, Complex V has a canonical subunit composition in other classes of Chlorophytes (Trebouxiophyceae, Prasinophyceae, and Ulvophyceae) as well as in Streptophytes (land plants) and in Rhodophytes (red algae). Growth, respiration and ATP levels in Chlorophyceae were also barely affected by oligomycin concentrations that affect representatives of the other classes of Chlorophytes. We finally studied the function of the Asa7 atypical subunit by using RNA interference in C. reinhardtii. Although the loss of Asa7 subunit has no impact on cell bioenergetics or mitochondrial structures, it destabilizes in vitro the enzyme dimeric form and renders growth, respiration and ATP level sensitive to oligomycins. Conclusions/Significance. Altogether, our results suggest that the loss of canonical components of the Complex V stator happened at the root of chlorophycean lineage and was accompanied by the recruitment of novel polypeptides. Such a massive modification of Complex V stator features might have conferred novel properties, including the stabilization of the enzyme dimeric form and the shielding of the proton channel. In these respects, we discuss an evolutionary scenario for F(1)F(O) ATP synthase in the whole green lineage (i.e. Chlorophyta and Streptophyta). [less ▲]

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See detail(Functionnal) analysis of hydrogen production in Chlamydomonas reinhardtii mitochondrial mutants
Lecler, Renaud ULg; Godaux, Damien ULg; Hamilton, Christopher ULg et al

Poster (2010, June 27)

Mitochondrial Chlamydomonas mutants for respiratory complexes present a decreased dark respiration and apparent yield of photosynthetic linear electron flow. They accumulate reducing power such as NAD(P)H ... [more ▼]

Mitochondrial Chlamydomonas mutants for respiratory complexes present a decreased dark respiration and apparent yield of photosynthetic linear electron flow. They accumulate reducing power such as NAD(P)H and show lower levels of ATP. Under restrictive conditions, like sulfur depletion and anoxia, Chlamydomonas is able to produce hydrogen towards the activation of a chloroplatic O2-sensitive Fe-hydrogenase which catalyses the reduction of electrons to H2. In this study we used an adapted Melis protocol to analyse hydrogen evolution of mitochondrial mutants. For this aim a simple-flask system was built with gaz collecting tubes. A parallel flask was used for GC analyses. [less ▲]

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