title: Peculiar properties of chlorophyll thermoluminescence emission of autotrophically or mixotrophically grown Chlamydomonas reinhardtii.
abstract: The microalgae Chlamydomonas reinhardtii and Chlorella sp. CCAP 211/84 were grown autotrophically and mixotrophically and their thermoluminescence emissions were recorded above 0 °C after excitation by 1, 2 or 3 xenon flashes or by continuous far-red light. An oscillation of the B band intensity according to the number of flashes was always observed, with a maximum after 2 flashes, accompanied by a downshift of the B band temperature maximum in mixotrophic compared to autotrophic grown cells, indicative of a dark stable pH gradient. Moreover, new flash-induced bands emerged in mixotrophic Chlamydomonas grown cells, at temperatures higher than that of the B band. In contrast to the afterglow band observed in higher plants, in Chlamydomonas these bands were not inducible by far-red light, were fully suppressed by 2 μM antimycin A, and peaked at different temperatures depending on the flash number and growth stage, with higher temperature maxima in cells at a stationary compared to an exponential growth stage. These differences are discussed according to the particular properties of cyclic electron transfer pathways in C. reinhardtii.
authors.affiliation: Groupe de Biospectroscopie Végétale, Ecophysiologie Végétale, ESE, Bât. 362, Université Paris-Sud-Orsay, 91400 Orsay, France. jean-marc.ducruet@u-psud.fr
authors.forename: Jean-Marc
authors.initials: JM
authors.lastname: Ducruet
authors.forename: Aurelio
authors.initials: A
authors.lastname: Serrano
authors.forename: Mercedes
authors.initials: M
authors.lastname: Roncel
authors.forename: José M
authors.initials: JM
authors.lastname: Ortega
mesh_terms: D000968:Antimycin A / Q000494:pharmacology; D016825:Chlamydomonas reinhardtii / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D002734:Chlorophyll / Q000737:chemistry* / Q000378:metabolism; D004579:Electron Transport; D006863:Hydrogen-Ion Concentration; D010766:Phosphorylation; D045332:Photosystem II Protein Complex / Q000737:chemistry / Q000378:metabolism; D013050:Spectrometry, Fluorescence; D013696:Temperature; D014978:Xenon / Q000737:chemistry
chemical_list: D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D014978:Xenon; D000968:Antimycin A