title: No reduction of energy metabolism in Clk mutants.
abstract: Mutation in any of the four clock genes (clk-1, clk-2, clk-3, gro-1) causes an average slowing down of many temporal processes, and an increase of mean life span. The latter effect has been linked to the slow phenotype, and it has been reasoned that any reduction of the rate of living would reduce the load of oxidative damage, which is thought to drive the ageing process. To test this model we measured several parameters describing metabolic output in wild type worms and all four Clk mutants. We found no gross changes in metabolic output, as assessed from oxygen consumption and heat production rates, lucigenin-mediated light production capacity, ATP content, and lipofuscin autofluorescence. Catalase and superoxide dismutase (SOD) were variably altered, but not cooperatively, as would be expected to enhance reactive oxygen species (ROS) scavenging activity. Thus we conclude that the prolonged life span of Clk mutants cannot be attributed to reduced metabolic rate or an increased activity of the major antioxidant enzymes catalase and SOD.
authors.affiliation: Department of Biology, Ghent University, K L Ledeganckstraat 35, B-9000, Ghent, Belgium.
authors.forename: Bart P
authors.initials: BP
authors.lastname: Braeckman
authors.forename: Koen
authors.initials: K
authors.lastname: Houthoofd
authors.forename: Kristel
authors.initials: K
authors.lastname: Brys
authors.forename: Isabelle
authors.initials: I
authors.lastname: Lenaerts
authors.forename: Annemie
authors.initials: A
authors.lastname: De Vreese
authors.forename: Sylvie
authors.initials: S
authors.lastname: Van Eygen
authors.forename: Hilda
authors.initials: H
authors.lastname: Raes
authors.forename: Jacques R
authors.initials: JR
authors.lastname: Vanfleteren
mesh_terms: D000166:Acridines / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D019883:Alkyl and Aryl Transferases / Q000235:genetics*; D000818:Animals; D017173:Caenorhabditis elegans; D029742:Caenorhabditis elegans Proteins / Q000235:genetics*; D002374:Catalase / Q000378:metabolism; D004734:Energy Metabolism / Q000502:physiology*; D005453:Fluorescence; D015801:Helminth Proteins / Q000235:genetics*; D008062:Lipofuscin / Q000502:physiology; D008136:Longevity; D008163:Luminescent Measurements; D009154:Mutation / Q000502:physiology*; D010101:Oxygen Consumption; D013482:Superoxide Dismutase / Q000378:metabolism; D034501:Telomere-Binding Proteins / Q000235:genetics*; D022722:Thermogenesis
chemical_list: D000166:Acridines; C104339:CLK-1 protein, C elegans; D029742:Caenorhabditis elegans Proteins; D015801:Helminth Proteins; D008062:Lipofuscin; D034501:Telomere-Binding Proteins; C438752:clk-2 protein, C elegans; C474209:clk-3 protein, C elegans; C033472:10,10'-dimethyl-9,9'-biacridinium; D000255:Adenosine Triphosphate; D002374:Catalase; D013482:Superoxide Dismutase; D019883:Alkyl and Aryl Transferases; C023197:tRNA isopentenyltransferase