title: Isolation of Chlamydomonas reinhardtii mutants with altered mitochondrial respiration by chlorophyll fluorescence measurement.
abstract: 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.
authors.affiliation: Genetics and Physiology of Microalgae, PhytoSYSTEMS, Department of Life Sciences, University of Liège, B-4000 Liège, Belgium.
authors.forename: Simon
authors.initials: S
authors.lastname: Massoz
authors.affiliation: Genetics and Physiology of Microalgae, PhytoSYSTEMS, Department of Life Sciences, University of Liège, B-4000 Liège, Belgium.
authors.forename: Véronique
authors.initials: V
authors.lastname: Larosa
authors.affiliation: Genetics and Physiology of Microalgae, PhytoSYSTEMS, Department of Life Sciences, University of Liège, B-4000 Liège, Belgium.
authors.forename: Bastien
authors.initials: B
authors.lastname: Horrion
authors.affiliation: Genetics and Physiology of Microalgae, PhytoSYSTEMS, Department of Life Sciences, University of Liège, B-4000 Liège, Belgium.
authors.forename: René F
authors.initials: RF
authors.lastname: Matagne
authors.affiliation: Genetics and Physiology of Microalgae, PhytoSYSTEMS, Department of Life Sciences, University of Liège, B-4000 Liège, Belgium.
authors.forename: Claire
authors.initials: C
authors.lastname: Remacle
authors.affiliation: Genetics and Physiology of Microalgae, PhytoSYSTEMS, Department of Life Sciences, University of Liège, B-4000 Liège, Belgium. Electronic address: pierre.cardol@ulg.ac.be.
authors.forename: Pierre
authors.initials: P
authors.lastname: Cardol
mesh_terms: D016825:Chlamydomonas reinhardtii / Q000235:genetics / Q000378:metabolism; D002734:Chlorophyll / Q000378:metabolism*; D005453:Fluorescence; D052836:Heterotrophic Processes; D008928:Mitochondria / Q000378:metabolism*; D016254:Mutagenesis, Insertional; D009154:Mutation; D010788:Photosynthesis
chemical_list: D002734:Chlorophyll
keywords: Fluorescence screening; Insertional mutants; Respiratory mutants