title: Influence of Starvation on Respiratory Metabolism and Pyridine Nucleotide Levels in the Marine Dinoflagellate Oxyrrhis marina.
abstract: Respiratory oxygen consumption rate (RO2) and potential respiration (Φ) has been monitored during a food deprivation period in the heterotrophic dinoflagellate Oxyrrhis marina. Φ was determined by measuring the activity of the enzymes from the electron transport system (ETS), the major contributor to the oxygen consumption in the cells. Additionally, we have quantified for the first time the concentration of pyridine nucleotides in this organism, both in their oxidized (NAD(P)(+)) and reduced forms (NAD(P)H). These molecules are the main electron donors at the beginning of the ETS. We observed a dramatic decrease in RO2 within the first days, whereas Φ steadily, but more gradually declined during the entire experiment. This led to a decrease of the RO2 /Φ with time. The intracellular total pool of NAD and NADP concentration, in turn, dropped exponentially in a manner parallel to the RO2. This strong decrease was mainly driven by a reduction in the concentration of the oxidized forms. The present work constitutes a first step in clarifying the role of intracellular NAD and NADP concentrations and the redox status in the control of in vivo RO2 in marine organisms.
authors.affiliation: Marine Ecophysiology Group (EOMAR), Universidad de Las Palmas de Gran Canaria, 35017, Canary Islands, Spain. Electronic address: nosma@becarios.ulpgc.es.
authors.forename: Natalia
authors.initials: N
authors.lastname: Osma
authors.affiliation: Marine Ecophysiology Group (EOMAR), Universidad de Las Palmas de Gran Canaria, 35017, Canary Islands, Spain.
authors.forename: Manuela
authors.initials: M
authors.lastname: Aristizabal
authors.affiliation: Marine Ecophysiology Group (EOMAR), Universidad de Las Palmas de Gran Canaria, 35017, Canary Islands, Spain.
authors.forename: Igor
authors.initials: I
authors.lastname: Fernández-Urruzola
authors.affiliation: Marine Ecophysiology Group (EOMAR), Universidad de Las Palmas de Gran Canaria, 35017, Canary Islands, Spain.
authors.forename: Theodore T
authors.initials: TT
authors.lastname: Packard
authors.affiliation: Marine Ecophysiology Group (EOMAR), Universidad de Las Palmas de Gran Canaria, 35017, Canary Islands, Spain.
authors.forename: May
authors.initials: M
authors.lastname: Gómez
mesh_terms: D000818:Animals; D004141:Dinoflagellida / Q000378:metabolism*; D004579:Electron Transport / Q000502:physiology*; D009249:NADP / Q000378:metabolism*; D010101:Oxygen Consumption / Q000502:physiology*; D012119:Respiration; D013217:Starvation / Q000503:physiopathology*; D015048:Zooplankton / Q000378:metabolism*
chemical_list: D009249:NADP
keywords: Electron transport system (ETS); food deprivation; microzooplankton.; nicotinamide adenine dinucleotide (NAD); nicotinamide adenine dinucleotide phosphate (NADP); respiration