Metabolomic analysis of the green microalga Chlamydomonas reinhardtii cultivated under day/night conditions.
Biomass composition of Chlamydomonas reinhardtii was studied during two consecutive cycles of 12h light/12h dark. As in our experimental conditions the two synchronized divisions were separated by 20h, it was possible to show that accumulation of dry weight, proteins, chlorophyll and fatty acids mainly depends on cell division, whereas starch accumulation depends on a circadian rhythm as reported previously. Our metabolomics analyses also revealed that accumulation of five (Ser, Val, Leu, Ile and Thr) of the nine free amino acids detected displayed rhythmicity, depending on cell division while Glu was 20-50 times more abundant than the other ones probably because this free amino acid serves not only for protein synthesis but also for biosynthesis of nitrogen compounds. In addition, we performed a thermodynamic-motivated theoretical approach known as 'surprisal analysis'. The results from this analysis showed that cells were close to a steady state all along the 48h of the experiment. In addition, calculation of free energy of cellular metabolites showed that the transition point, i.e. the state which immediately precedes cell division, corresponds to the most unstable stage of the cell cycle and that division is identified as the greatest drop in the free energy of metabolites.
Genetics and Physiology of Microalgae, Institute of Botany, B22, University of Liège, Belgium.
Rémi
R
Willamme
Centre of Analytical Research and Technology (CART) - LSM/Inorganic Analytical Chemistry, Department of Chemistry, B6C, University of Liège, Belgium.
Zouheir
Z
Alsafra
The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel.
Rameshkumar
R
Arumugam
Centre of Analytical Research and Technology (CART) - LSM/Inorganic Analytical Chemistry, Department of Chemistry, B6C, University of Liège, Belgium.
Gauthier
G
Eppe
The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel; Theoretical Physical Chemistry, Department of Chemistry, B6C, University of Liège, Belgium.
Françoise
F
Remacle
The Fritz Haber Research Center for Molecular Dynamics, Institute of Chemistry, Hebrew University of Jerusalem, Jerusalem 91904, Israel; Department of Molecular and Medical Pharmacology, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA.
R D
RD
Levine
Genetics and Physiology of Microalgae, Institute of Botany, B22, University of Liège, Belgium. Electronic address: c.remacle@ulg.ac.be.
Claire
C
Remacle
D020418:Algal Proteins / Q000032:analysis; D000596:Amino Acids / Q000032:analysis; D018533:Biomass; D002455:Cell Division; D016825:Chlamydomonas reinhardtii / Q000254:growth & development / Q000378:metabolism*; D002734:Chlorophyll / Q000032:analysis; D002940:Circadian Rhythm; D005227:Fatty Acids / Q000032:analysis; D055432:Metabolomics
D020418:Algal Proteins; D000596:Amino Acids; D005227:Fatty Acids; D002734:Chlorophyll
Chlamydomonas; Day/night cycle; Metabolomics; Surprisal analysis