title: Proliferating bloodstream-form Trypanosoma brucei use a negligible part of consumed glucose for anabolic processes.
abstract: Our quantitative knowledge of carbon fluxes in the long slender bloodstream form (BSF) Trypanosoma brucei is mainly based on non-proliferating parasites, isolated from laboratory animals and kept in buffers. In this paper we present a carbon balance for exponentially growing bloodstream form trypanosomes. The cells grew with a doubling time of 5.3h, contained 46 μ mol of carbon (10(8) cells)(-1) and had a glucose consumption flux of 160 nmol min(-1) (10(8) cells)(-1). The molar ratio of pyruvate excreted versus glucose consumed was 2.1. Furthermore, analysis of the (13)C label distribution in pyruvate in (13)C-glucose incubations of exponentially growing trypanosomes showed that glucose was the sole substrate for pyruvate production. We conclude that the glucose metabolised in glycolysis was hardly, if at all, used for biosynthetic processes. Carbon flux through glycolysis in exponentially growing trypanosomes was 10 times higher than the incorporation of carbon into biomass. This biosynthetic carbon is derived from other precursors present in the nutrient rich growth medium. Furthermore, we found that the glycolytic flux was unaltered when the culture went into stationary phase, suggesting that most of the ATP produced in glycolysis is used for processes other than growth.
authors.affiliation: Department of Molecular Cell Physiology, Faculty of Earth and Life Sciences, Vrije Universiteit Amsterdam, De Boelelaan 1085, NL-1081 HV Amsterdam, The Netherlands.
authors.forename: Jurgen R
authors.initials: JR
authors.lastname: Haanstra
authors.forename: Arjen
authors.initials: A
authors.lastname: van Tuijl
authors.forename: Jan
authors.initials: J
authors.lastname: van Dam
authors.forename: Wouter
authors.initials: W
authors.lastname: van Winden
authors.forename: Aloysius G M
authors.initials: AG
authors.lastname: Tielens
authors.forename: Jaap J
authors.initials: JJ
authors.lastname: van Hellemond
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Bakker
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D018533:Biomass; D001769:Blood / Q000469:parasitology*; D002247:Carbon Isotopes / Q000378:metabolism; D003470:Culture Media / Q000737:chemistry; D004734:Energy Metabolism; D005947:Glucose / Q000378:metabolism*; D006019:Glycolysis; D007553:Isotope Labeling / Q000379:methods; D019289:Pyruvic Acid / Q000378:metabolism; D013997:Time Factors; D014346:Trypanosoma brucei brucei / Q000737:chemistry / Q000254:growth & development* / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D003470:Culture Media; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D005947:Glucose