title: Dietary restriction by growth in axenic medium induces discrete changes in the transcriptional output of genes involved in energy metabolism in Caenorhabditis elegans.
abstract: Dietary restriction increases life span in a wide range of species, including the nematode worm Caenorhabditis elegans. The mechanism by which it does so remains largely unknown, although it is commonly thought that a reduction of reactive oxygen species (ROS) plays a pivotal role. More specifically, for C. elegans, it has been proposed that food restriction reduces energy expenditure, possibly in conjunction with an anaerobic shift in energy production, with consequent reduction in the formation of ROS. We have measured differential transcript abundance of 49 genes known to play roles in energy metabolism in axenic culture medium, which causes a nutritional deficit and leads to a substantial increase of life span. We found no evidence for a reduction in metabolic rate or a shift to anaerobic metabolism in axenic culture. Major changes induced by growth in axenic medium include down-regulation of lipid degradation and up-regulation of glyoxylate cycle activity glyceroneogenesis and, possibly, gluconeogenesis. The activities determined in worm extracts for pyruvate kinase, phosphoenolpyruvate carboxykinase and isocitrate lyase followed a similar trend. We conclude that growth in axenic culture is marked by a general up-regulation of replenishing pathways.
authors.affiliation: Department of Biology, Ghent University, Ghent, Belgium.
authors.forename: Natascha
authors.initials: N
authors.lastname: Castelein
authors.forename: David
authors.initials: D
authors.lastname: Hoogewijs
authors.forename: Annemie
authors.initials: A
authors.lastname: De Vreese
authors.forename: Bart P
authors.initials: BP
authors.lastname: Braeckman
authors.forename: Jacques R
authors.initials: JR
authors.lastname: Vanfleteren
mesh_terms: D000818:Animals; D017173:Caenorhabditis elegans / Q000254:growth & development*; D029742:Caenorhabditis elegans Proteins / Q000378:metabolism*; D031204:Caloric Restriction / Q000379:methods*; D004734:Energy Metabolism / Q000502:physiology*; D018507:Gene Expression Regulation, Developmental / Q000502:physiology*; D005856:Germ-Free Life / Q000502:physiology*; D015533:Transcriptional Activation / Q000502:physiology*
chemical_list: D029742:Caenorhabditis elegans Proteins